// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_dir2.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_trans.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_bmap_btree.h"
#include "xfs_rtbitmap.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_trans_space.h"
#include "xfs_buf_item.h"
#include "xfs_trace.h"
#include "xfs_attr_leaf.h"
#include "xfs_filestream.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_refcount.h"
#include "xfs_iomap.h"
#include "xfs_health.h"
#include "xfs_bmap_item.h"
#include "xfs_symlink_remote.h"
#include "xfs_inode_util.h"
#include "xfs_rtgroup.h"
#include "xfs_zone_alloc.h"

struct kmem_cache               *xfs_bmap_intent_cache;

/*
 * Miscellaneous helper functions
 */

/*
 * Compute and fill in the value of the maximum depth of a bmap btree
 * in this filesystem.  Done once, during mount.
 */
void
xfs_bmap_compute_maxlevels(
        xfs_mount_t     *mp,            /* file system mount structure */
        int             whichfork)      /* data or attr fork */
{
        uint64_t        maxblocks;      /* max blocks at this level */
        xfs_extnum_t    maxleafents;    /* max leaf entries possible */
        int             level;          /* btree level */
        int             maxrootrecs;    /* max records in root block */
        int             minleafrecs;    /* min records in leaf block */
        int             minnoderecs;    /* min records in node block */
        int             sz;             /* root block size */

        /*
         * The maximum number of extents in a fork, hence the maximum number of
         * leaf entries, is controlled by the size of the on-disk extent count.
         *
         * Note that we can no longer assume that if we are in ATTR1 that the
         * fork offset of all the inodes will be
         * (xfs_default_attroffset(ip) >> 3) because we could have mounted with
         * ATTR2 and then mounted back with ATTR1, keeping the i_forkoff's fixed
         * but probably at various positions. Therefore, for both ATTR1 and
         * ATTR2 we have to assume the worst case scenario of a minimum size
         * available.
         */
        maxleafents = xfs_iext_max_nextents(xfs_has_large_extent_counts(mp),
                                whichfork);
        if (whichfork == XFS_DATA_FORK)
                sz = xfs_bmdr_space_calc(MINDBTPTRS);
        else
                sz = xfs_bmdr_space_calc(MINABTPTRS);

        maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
        minleafrecs = mp->m_bmap_dmnr[0];
        minnoderecs = mp->m_bmap_dmnr[1];
        maxblocks = howmany_64(maxleafents, minleafrecs);
        for (level = 1; maxblocks > 1; level++) {
                if (maxblocks <= maxrootrecs)
                        maxblocks = 1;
                else
                        maxblocks = howmany_64(maxblocks, minnoderecs);
        }
        mp->m_bm_maxlevels[whichfork] = level;
        ASSERT(mp->m_bm_maxlevels[whichfork] <= xfs_bmbt_maxlevels_ondisk());
}

unsigned int
xfs_bmap_compute_attr_offset(
        struct xfs_mount        *mp)
{
        if (mp->m_sb.sb_inodesize == 256)
                return XFS_LITINO(mp) - xfs_bmdr_space_calc(MINABTPTRS);
        return xfs_bmdr_space_calc(6 * MINABTPTRS);
}

STATIC int                              /* error */
xfs_bmbt_lookup_eq(
        struct xfs_btree_cur    *cur,
        struct xfs_bmbt_irec    *irec,
        int                     *stat)  /* success/failure */
{
        cur->bc_rec.b = *irec;
        return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
}

STATIC int                              /* error */
xfs_bmbt_lookup_first(
        struct xfs_btree_cur    *cur,
        int                     *stat)  /* success/failure */
{
        cur->bc_rec.b.br_startoff = 0;
        cur->bc_rec.b.br_startblock = 0;
        cur->bc_rec.b.br_blockcount = 0;
        return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
}

/*
 * Check if the inode needs to be converted to btree format.
 */
static inline bool xfs_bmap_needs_btree(struct xfs_inode *ip, int whichfork)
{
        struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);

        return whichfork != XFS_COW_FORK &&
                ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
                ifp->if_nextents > XFS_IFORK_MAXEXT(ip, whichfork);
}

/*
 * Check if the inode should be converted to extent format.
 */
static inline bool xfs_bmap_wants_extents(struct xfs_inode *ip, int whichfork)
{
        struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);

        return whichfork != XFS_COW_FORK &&
                ifp->if_format == XFS_DINODE_FMT_BTREE &&
                ifp->if_nextents <= XFS_IFORK_MAXEXT(ip, whichfork);
}

/*
 * Update the record referred to by cur to the value given by irec
 * This either works (return 0) or gets an EFSCORRUPTED error.
 */
STATIC int
xfs_bmbt_update(
        struct xfs_btree_cur    *cur,
        struct xfs_bmbt_irec    *irec)
{
        union xfs_btree_rec     rec;

        xfs_bmbt_disk_set_all(&rec.bmbt, irec);
        return xfs_btree_update(cur, &rec);
}

/*
 * Compute the worst-case number of indirect blocks that will be used
 * for ip's delayed extent of length "len".
 */
xfs_filblks_t
xfs_bmap_worst_indlen(
        struct xfs_inode        *ip,            /* incore inode pointer */
        xfs_filblks_t           len)            /* delayed extent length */
{
        struct xfs_mount        *mp = ip->i_mount;
        int                     maxrecs = mp->m_bmap_dmxr[0];
        int                     level;
        xfs_filblks_t           rval;

        for (level = 0, rval = 0;
             level < XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK);
             level++) {
                len += maxrecs - 1;
                do_div(len, maxrecs);
                rval += len;
                if (len == 1)
                        return rval + XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) -
                                level - 1;
                if (level == 0)
                        maxrecs = mp->m_bmap_dmxr[1];
        }
        return rval;
}

/*
 * Calculate the default attribute fork offset for newly created inodes.
 */
uint
xfs_default_attroffset(
        struct xfs_inode        *ip)
{
        if (ip->i_df.if_format == XFS_DINODE_FMT_DEV)
                return roundup(sizeof(xfs_dev_t), 8);
        return M_IGEO(ip->i_mount)->attr_fork_offset;
}

/*
 * Helper routine to reset inode i_forkoff field when switching attribute fork
 * from local to extent format - we reset it where possible to make space
 * available for inline data fork extents.
 */
STATIC void
xfs_bmap_forkoff_reset(
        xfs_inode_t     *ip,
        int             whichfork)
{
        if (whichfork == XFS_ATTR_FORK &&
            ip->i_df.if_format != XFS_DINODE_FMT_DEV &&
            ip->i_df.if_format != XFS_DINODE_FMT_BTREE) {
                uint    dfl_forkoff = xfs_default_attroffset(ip) >> 3;

                if (dfl_forkoff > ip->i_forkoff)
                        ip->i_forkoff = dfl_forkoff;
        }
}

static int
xfs_bmap_read_buf(
        struct xfs_mount        *mp,            /* file system mount point */
        struct xfs_trans        *tp,            /* transaction pointer */
        xfs_fsblock_t           fsbno,          /* file system block number */
        struct xfs_buf          **bpp)          /* buffer for fsbno */
{
        struct xfs_buf          *bp;            /* return value */
        int                     error;

        if (!xfs_verify_fsbno(mp, fsbno))
                return -EFSCORRUPTED;
        error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
                        XFS_FSB_TO_DADDR(mp, fsbno), mp->m_bsize, 0, &bp,
                        &xfs_bmbt_buf_ops);
        if (!error) {
                xfs_buf_set_ref(bp, XFS_BMAP_BTREE_REF);
                *bpp = bp;
        }
        return error;
}

#ifdef DEBUG
STATIC struct xfs_buf *
xfs_bmap_get_bp(
        struct xfs_btree_cur    *cur,
        xfs_fsblock_t           bno)
{
        struct xfs_log_item     *lip;
        int                     i;

        if (!cur)
                return NULL;

        for (i = 0; i < cur->bc_maxlevels; i++) {
                if (!cur->bc_levels[i].bp)
                        break;
                if (xfs_buf_daddr(cur->bc_levels[i].bp) == bno)
                        return cur->bc_levels[i].bp;
        }

        /* Chase down all the log items to see if the bp is there */
        list_for_each_entry(lip, &cur->bc_tp->t_items, li_trans) {
                struct xfs_buf_log_item *bip = (struct xfs_buf_log_item *)lip;

                if (bip->bli_item.li_type == XFS_LI_BUF &&
                    xfs_buf_daddr(bip->bli_buf) == bno)
                        return bip->bli_buf;
        }

        return NULL;
}

STATIC void
xfs_check_block(
        struct xfs_btree_block  *block,
        xfs_mount_t             *mp,
        int                     root,
        short                   sz)
{
        int                     i, j, dmxr;
        __be64                  *pp, *thispa;   /* pointer to block address */
        xfs_bmbt_key_t          *prevp, *keyp;

        ASSERT(be16_to_cpu(block->bb_level) > 0);

        prevp = NULL;
        for( i = 1; i <= xfs_btree_get_numrecs(block); i++) {
                dmxr = mp->m_bmap_dmxr[0];
                keyp = xfs_bmbt_key_addr(mp, block, i);

                if (prevp) {
                        ASSERT(be64_to_cpu(prevp->br_startoff) <
                               be64_to_cpu(keyp->br_startoff));
                }
                prevp = keyp;

                /*
                 * Compare the block numbers to see if there are dups.
                 */
                if (root)
                        pp = xfs_bmap_broot_ptr_addr(mp, block, i, sz);
                else
                        pp = xfs_bmbt_ptr_addr(mp, block, i, dmxr);

                for (j = i+1; j <= be16_to_cpu(block->bb_numrecs); j++) {
                        if (root)
                                thispa = xfs_bmap_broot_ptr_addr(mp, block, j, sz);
                        else
                                thispa = xfs_bmbt_ptr_addr(mp, block, j, dmxr);
                        if (*thispa == *pp) {
                                xfs_warn(mp, "%s: thispa(%d) == pp(%d) %lld",
                                        __func__, j, i,
                                        (unsigned long long)be64_to_cpu(*thispa));
                                xfs_err(mp, "%s: ptrs are equal in node\n",
                                        __func__);
                                xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
                        }
                }
        }
}

/*
 * Check that the extents for the inode ip are in the right order in all
 * btree leaves. THis becomes prohibitively expensive for large extent count
 * files, so don't bother with inodes that have more than 10,000 extents in
 * them. The btree record ordering checks will still be done, so for such large
 * bmapbt constructs that is going to catch most corruptions.
 */
STATIC void
xfs_bmap_check_leaf_extents(
        struct xfs_btree_cur    *cur,   /* btree cursor or null */
        xfs_inode_t             *ip,            /* incore inode pointer */
        int                     whichfork)      /* data or attr fork */
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_btree_block  *block; /* current btree block */
        xfs_fsblock_t           bno;    /* block # of "block" */
        struct xfs_buf          *bp;    /* buffer for "block" */
        int                     error;  /* error return value */
        xfs_extnum_t            i=0, j; /* index into the extents list */
        int                     level;  /* btree level, for checking */
        __be64                  *pp;    /* pointer to block address */
        xfs_bmbt_rec_t          *ep;    /* pointer to current extent */
        xfs_bmbt_rec_t          last = {0, 0}; /* last extent in prev block */
        xfs_bmbt_rec_t          *nextp; /* pointer to next extent */
        int                     bp_release = 0;

        if (ifp->if_format != XFS_DINODE_FMT_BTREE)
                return;

        /* skip large extent count inodes */
        if (ip->i_df.if_nextents > 10000)
                return;

        bno = NULLFSBLOCK;
        block = ifp->if_broot;
        /*
         * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
         */
        level = be16_to_cpu(block->bb_level);
        ASSERT(level > 0);
        xfs_check_block(block, mp, 1, ifp->if_broot_bytes);
        pp = xfs_bmap_broot_ptr_addr(mp, block, 1, ifp->if_broot_bytes);
        bno = be64_to_cpu(*pp);

        ASSERT(bno != NULLFSBLOCK);
        ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
        ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);

        /*
         * Go down the tree until leaf level is reached, following the first
         * pointer (leftmost) at each level.
         */
        while (level-- > 0) {
                /* See if buf is in cur first */
                bp_release = 0;
                bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
                if (!bp) {
                        bp_release = 1;
                        error = xfs_bmap_read_buf(mp, NULL, bno, &bp);
                        if (xfs_metadata_is_sick(error))
                                xfs_btree_mark_sick(cur);
                        if (error)
                                goto error_norelse;
                }
                block = XFS_BUF_TO_BLOCK(bp);
                if (level == 0)
                        break;

                /*
                 * Check this block for basic sanity (increasing keys and
                 * no duplicate blocks).
                 */

                xfs_check_block(block, mp, 0, 0);
                pp = xfs_bmbt_ptr_addr(mp, block, 1, mp->m_bmap_dmxr[1]);
                bno = be64_to_cpu(*pp);
                if (XFS_IS_CORRUPT(mp, !xfs_verify_fsbno(mp, bno))) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        goto error0;
                }
                if (bp_release) {
                        bp_release = 0;
                        xfs_trans_brelse(NULL, bp);
                }
        }

        /*
         * Here with bp and block set to the leftmost leaf node in the tree.
         */
        i = 0;

        /*
         * Loop over all leaf nodes checking that all extents are in the right order.
         */
        for (;;) {
                xfs_fsblock_t   nextbno;
                xfs_extnum_t    num_recs;


                num_recs = xfs_btree_get_numrecs(block);

                /*
                 * Read-ahead the next leaf block, if any.
                 */

                nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);

                /*
                 * Check all the extents to make sure they are OK.
                 * If we had a previous block, the last entry should
                 * conform with the first entry in this one.
                 */

                ep = xfs_bmbt_rec_addr(mp, block, 1);
                if (i) {
                        ASSERT(xfs_bmbt_disk_get_startoff(&last) +
                               xfs_bmbt_disk_get_blockcount(&last) <=
                               xfs_bmbt_disk_get_startoff(ep));
                }
                for (j = 1; j < num_recs; j++) {
                        nextp = xfs_bmbt_rec_addr(mp, block, j + 1);
                        ASSERT(xfs_bmbt_disk_get_startoff(ep) +
                               xfs_bmbt_disk_get_blockcount(ep) <=
                               xfs_bmbt_disk_get_startoff(nextp));
                        ep = nextp;
                }

                last = *ep;
                i += num_recs;
                if (bp_release) {
                        bp_release = 0;
                        xfs_trans_brelse(NULL, bp);
                }
                bno = nextbno;
                /*
                 * If we've reached the end, stop.
                 */
                if (bno == NULLFSBLOCK)
                        break;

                bp_release = 0;
                bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
                if (!bp) {
                        bp_release = 1;
                        error = xfs_bmap_read_buf(mp, NULL, bno, &bp);
                        if (xfs_metadata_is_sick(error))
                                xfs_btree_mark_sick(cur);
                        if (error)
                                goto error_norelse;
                }
                block = XFS_BUF_TO_BLOCK(bp);
        }

        return;

error0:
        xfs_warn(mp, "%s: at error0", __func__);
        if (bp_release)
                xfs_trans_brelse(NULL, bp);
error_norelse:
        xfs_warn(mp, "%s: BAD after btree leaves for %llu extents",
                __func__, i);
        xfs_err(mp, "%s: CORRUPTED BTREE OR SOMETHING", __func__);
        xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
        return;
}

/*
 * Validate that the bmbt_irecs being returned from bmapi are valid
 * given the caller's original parameters.  Specifically check the
 * ranges of the returned irecs to ensure that they only extend beyond
 * the given parameters if the XFS_BMAPI_ENTIRE flag was set.
 */
STATIC void
xfs_bmap_validate_ret(
        xfs_fileoff_t           bno,
        xfs_filblks_t           len,
        uint32_t                flags,
        xfs_bmbt_irec_t         *mval,
        int                     nmap,
        int                     ret_nmap)
{
        int                     i;              /* index to map values */

        ASSERT(ret_nmap <= nmap);

        for (i = 0; i < ret_nmap; i++) {
                ASSERT(mval[i].br_blockcount > 0);
                if (!(flags & XFS_BMAPI_ENTIRE)) {
                        ASSERT(mval[i].br_startoff >= bno);
                        ASSERT(mval[i].br_blockcount <= len);
                        ASSERT(mval[i].br_startoff + mval[i].br_blockcount <=
                               bno + len);
                } else {
                        ASSERT(mval[i].br_startoff < bno + len);
                        ASSERT(mval[i].br_startoff + mval[i].br_blockcount >
                               bno);
                }
                ASSERT(i == 0 ||
                       mval[i - 1].br_startoff + mval[i - 1].br_blockcount ==
                       mval[i].br_startoff);
                ASSERT(mval[i].br_startblock != DELAYSTARTBLOCK &&
                       mval[i].br_startblock != HOLESTARTBLOCK);
                ASSERT(mval[i].br_state == XFS_EXT_NORM ||
                       mval[i].br_state == XFS_EXT_UNWRITTEN);
        }
}

#else
#define xfs_bmap_check_leaf_extents(cur, ip, whichfork)         do { } while (0)
#define xfs_bmap_validate_ret(bno,len,flags,mval,onmap,nmap)    do { } while (0)
#endif /* DEBUG */

/*
 * Inode fork format manipulation functions
 */

/*
 * Convert the inode format to extent format if it currently is in btree format,
 * but the extent list is small enough that it fits into the extent format.
 *
 * Since the extents are already in-core, all we have to do is give up the space
 * for the btree root and pitch the leaf block.
 */
STATIC int                              /* error */
xfs_bmap_btree_to_extents(
        struct xfs_trans        *tp,    /* transaction pointer */
        struct xfs_inode        *ip,    /* incore inode pointer */
        struct xfs_btree_cur    *cur,   /* btree cursor */
        int                     *logflagsp, /* inode logging flags */
        int                     whichfork)  /* data or attr fork */
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_btree_block  *rblock = ifp->if_broot;
        struct xfs_btree_block  *cblock;/* child btree block */
        xfs_fsblock_t           cbno;   /* child block number */
        struct xfs_buf          *cbp;   /* child block's buffer */
        int                     error;  /* error return value */
        __be64                  *pp;    /* ptr to block address */
        struct xfs_owner_info   oinfo;

        /* check if we actually need the extent format first: */
        if (!xfs_bmap_wants_extents(ip, whichfork))
                return 0;

        ASSERT(cur);
        ASSERT(whichfork != XFS_COW_FORK);
        ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE);
        ASSERT(be16_to_cpu(rblock->bb_level) == 1);
        ASSERT(be16_to_cpu(rblock->bb_numrecs) == 1);
        ASSERT(xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, false) == 1);

        pp = xfs_bmap_broot_ptr_addr(mp, rblock, 1, ifp->if_broot_bytes);
        cbno = be64_to_cpu(*pp);
#ifdef DEBUG
        if (XFS_IS_CORRUPT(cur->bc_mp, !xfs_verify_fsbno(mp, cbno))) {
                xfs_btree_mark_sick(cur);
                return -EFSCORRUPTED;
        }
#endif
        error = xfs_bmap_read_buf(mp, tp, cbno, &cbp);
        if (xfs_metadata_is_sick(error))
                xfs_btree_mark_sick(cur);
        if (error)
                return error;
        cblock = XFS_BUF_TO_BLOCK(cbp);
        if ((error = xfs_btree_check_block(cur, cblock, 0, cbp)))
                return error;

        xfs_rmap_ino_bmbt_owner(&oinfo, ip->i_ino, whichfork);
        error = xfs_free_extent_later(cur->bc_tp, cbno, 1, &oinfo,
                        XFS_AG_RESV_NONE, 0);
        if (error)
                return error;

        ip->i_nblocks--;
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
        xfs_trans_binval(tp, cbp);
        if (cur->bc_levels[0].bp == cbp)
                cur->bc_levels[0].bp = NULL;
        xfs_bmap_broot_realloc(ip, whichfork, 0);
        ASSERT(ifp->if_broot == NULL);
        ifp->if_format = XFS_DINODE_FMT_EXTENTS;
        *logflagsp |= XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
        return 0;
}

/*
 * Convert an extents-format file into a btree-format file.
 * The new file will have a root block (in the inode) and a single child block.
 */
STATIC int                                      /* error */
xfs_bmap_extents_to_btree(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode pointer */
        struct xfs_btree_cur    **curp,         /* cursor returned to caller */
        int                     wasdel,         /* converting a delayed alloc */
        int                     *logflagsp,     /* inode logging flags */
        int                     whichfork)      /* data or attr fork */
{
        struct xfs_btree_block  *ablock;        /* allocated (child) bt block */
        struct xfs_buf          *abp;           /* buffer for ablock */
        struct xfs_alloc_arg    args;           /* allocation arguments */
        struct xfs_bmbt_rec     *arp;           /* child record pointer */
        struct xfs_btree_block  *block;         /* btree root block */
        struct xfs_btree_cur    *cur;           /* bmap btree cursor */
        int                     error;          /* error return value */
        struct xfs_ifork        *ifp;           /* inode fork pointer */
        struct xfs_bmbt_key     *kp;            /* root block key pointer */
        struct xfs_mount        *mp;            /* mount structure */
        xfs_bmbt_ptr_t          *pp;            /* root block address pointer */
        struct xfs_iext_cursor  icur;
        struct xfs_bmbt_irec    rec;
        xfs_extnum_t            cnt = 0;

        mp = ip->i_mount;
        ASSERT(whichfork != XFS_COW_FORK);
        ifp = xfs_ifork_ptr(ip, whichfork);
        ASSERT(ifp->if_format == XFS_DINODE_FMT_EXTENTS);

        /*
         * Make space in the inode incore. This needs to be undone if we fail
         * to expand the root.
         */
        block = xfs_bmap_broot_realloc(ip, whichfork, 1);

        /*
         * Fill in the root.
         */
        xfs_bmbt_init_block(ip, block, NULL, 1, 1);
        /*
         * Need a cursor.  Can't allocate until bb_level is filled in.
         */
        cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
        if (wasdel)
                cur->bc_flags |= XFS_BTREE_BMBT_WASDEL;
        /*
         * Convert to a btree with two levels, one record in root.
         */
        ifp->if_format = XFS_DINODE_FMT_BTREE;
        memset(&args, 0, sizeof(args));
        args.tp = tp;
        args.mp = mp;
        xfs_rmap_ino_bmbt_owner(&args.oinfo, ip->i_ino, whichfork);

        args.minlen = args.maxlen = args.prod = 1;
        args.wasdel = wasdel;
        *logflagsp = 0;
        error = xfs_alloc_vextent_start_ag(&args,
                                XFS_INO_TO_FSB(mp, ip->i_ino));
        if (error)
                goto out_root_realloc;

        /*
         * Allocation can't fail, the space was reserved.
         */
        if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {
                error = -ENOSPC;
                goto out_root_realloc;
        }

        cur->bc_bmap.allocated++;
        ip->i_nblocks++;
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L);
        error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
                        XFS_FSB_TO_DADDR(mp, args.fsbno),
                        mp->m_bsize, 0, &abp);
        if (error)
                goto out_unreserve_dquot;

        /*
         * Fill in the child block.
         */
        ablock = XFS_BUF_TO_BLOCK(abp);
        xfs_bmbt_init_block(ip, ablock, abp, 0, 0);

        for_each_xfs_iext(ifp, &icur, &rec) {
                if (isnullstartblock(rec.br_startblock))
                        continue;
                arp = xfs_bmbt_rec_addr(mp, ablock, 1 + cnt);
                xfs_bmbt_disk_set_all(arp, &rec);
                cnt++;
        }
        ASSERT(cnt == ifp->if_nextents);
        xfs_btree_set_numrecs(ablock, cnt);

        /*
         * Fill in the root key and pointer.
         */
        kp = xfs_bmbt_key_addr(mp, block, 1);
        arp = xfs_bmbt_rec_addr(mp, ablock, 1);
        kp->br_startoff = cpu_to_be64(xfs_bmbt_disk_get_startoff(arp));
        pp = xfs_bmbt_ptr_addr(mp, block, 1, xfs_bmbt_get_maxrecs(cur,
                                                be16_to_cpu(block->bb_level)));
        *pp = cpu_to_be64(args.fsbno);

        /*
         * Do all this logging at the end so that
         * the root is at the right level.
         */
        xfs_btree_log_block(cur, abp, XFS_BB_ALL_BITS);
        xfs_btree_log_recs(cur, abp, 1, be16_to_cpu(ablock->bb_numrecs));
        ASSERT(*curp == NULL);
        *curp = cur;
        *logflagsp = XFS_ILOG_CORE | xfs_ilog_fbroot(whichfork);
        return 0;

out_unreserve_dquot:
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
out_root_realloc:
        xfs_bmap_broot_realloc(ip, whichfork, 0);
        ifp->if_format = XFS_DINODE_FMT_EXTENTS;
        ASSERT(ifp->if_broot == NULL);
        xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);

        return error;
}

/*
 * Convert a local file to an extents file.
 * This code is out of bounds for data forks of regular files,
 * since the file data needs to get logged so things will stay consistent.
 * (The bmap-level manipulations are ok, though).
 */
void
xfs_bmap_local_to_extents_empty(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);

        ASSERT(whichfork != XFS_COW_FORK);
        ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
        ASSERT(ifp->if_bytes == 0);
        ASSERT(ifp->if_nextents == 0);

        xfs_bmap_forkoff_reset(ip, whichfork);
        ifp->if_data = NULL;
        ifp->if_height = 0;
        ifp->if_format = XFS_DINODE_FMT_EXTENTS;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
}


int                                     /* error */
xfs_bmap_local_to_extents(
        xfs_trans_t     *tp,            /* transaction pointer */
        xfs_inode_t     *ip,            /* incore inode pointer */
        xfs_extlen_t    total,          /* total blocks needed by transaction */
        int             *logflagsp,     /* inode logging flags */
        int             whichfork,
        void            (*init_fn)(struct xfs_trans *tp,
                                   struct xfs_buf *bp,
                                   struct xfs_inode *ip,
                                   struct xfs_ifork *ifp, void *priv),
        void            *priv)
{
        int             error = 0;
        int             flags;          /* logging flags returned */
        struct xfs_ifork *ifp;          /* inode fork pointer */
        xfs_alloc_arg_t args;           /* allocation arguments */
        struct xfs_buf  *bp;            /* buffer for extent block */
        struct xfs_bmbt_irec rec;
        struct xfs_iext_cursor icur;

        /*
         * We don't want to deal with the case of keeping inode data inline yet.
         * So sending the data fork of a regular inode is invalid.
         */
        ASSERT(!(S_ISREG(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK));
        ifp = xfs_ifork_ptr(ip, whichfork);
        ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);

        if (!ifp->if_bytes) {
                xfs_bmap_local_to_extents_empty(tp, ip, whichfork);
                flags = XFS_ILOG_CORE;
                goto done;
        }

        flags = 0;
        error = 0;
        memset(&args, 0, sizeof(args));
        args.tp = tp;
        args.mp = ip->i_mount;
        args.total = total;
        args.minlen = args.maxlen = args.prod = 1;
        xfs_rmap_ino_owner(&args.oinfo, ip->i_ino, whichfork, 0);

        /*
         * Allocate a block.  We know we need only one, since the
         * file currently fits in an inode.
         */
        args.total = total;
        args.minlen = args.maxlen = args.prod = 1;
        error = xfs_alloc_vextent_start_ag(&args,
                        XFS_INO_TO_FSB(args.mp, ip->i_ino));
        if (error)
                goto done;

        /* Can't fail, the space was reserved. */
        ASSERT(args.fsbno != NULLFSBLOCK);
        ASSERT(args.len == 1);
        error = xfs_trans_get_buf(tp, args.mp->m_ddev_targp,
                        XFS_FSB_TO_DADDR(args.mp, args.fsbno),
                        args.mp->m_bsize, 0, &bp);
        if (error)
                goto done;

        /*
         * Initialize the block, copy the data and log the remote buffer.
         *
         * The callout is responsible for logging because the remote format
         * might differ from the local format and thus we don't know how much to
         * log here. Note that init_fn must also set the buffer log item type
         * correctly.
         */
        init_fn(tp, bp, ip, ifp, priv);

        /* account for the change in fork size */
        xfs_idata_realloc(ip, -ifp->if_bytes, whichfork);
        xfs_bmap_local_to_extents_empty(tp, ip, whichfork);
        flags |= XFS_ILOG_CORE;

        ifp->if_data = NULL;
        ifp->if_height = 0;

        rec.br_startoff = 0;
        rec.br_startblock = args.fsbno;
        rec.br_blockcount = 1;
        rec.br_state = XFS_EXT_NORM;
        xfs_iext_first(ifp, &icur);
        xfs_iext_insert(ip, &icur, &rec, 0);

        ifp->if_nextents = 1;
        ip->i_nblocks = 1;
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L);
        flags |= xfs_ilog_fext(whichfork);

done:
        *logflagsp = flags;
        return error;
}

/*
 * Called from xfs_bmap_add_attrfork to handle btree format files.
 */
STATIC int                                      /* error */
xfs_bmap_add_attrfork_btree(
        xfs_trans_t             *tp,            /* transaction pointer */
        xfs_inode_t             *ip,            /* incore inode pointer */
        int                     *flags)         /* inode logging flags */
{
        struct xfs_btree_block  *block = ip->i_df.if_broot;
        struct xfs_btree_cur    *cur;           /* btree cursor */
        int                     error;          /* error return value */
        xfs_mount_t             *mp;            /* file system mount struct */
        int                     stat;           /* newroot status */

        mp = ip->i_mount;

        if (xfs_bmap_bmdr_space(block) <= xfs_inode_data_fork_size(ip))
                *flags |= XFS_ILOG_DBROOT;
        else {
                cur = xfs_bmbt_init_cursor(mp, tp, ip, XFS_DATA_FORK);
                error = xfs_bmbt_lookup_first(cur, &stat);
                if (error)
                        goto error0;
                /* must be at least one entry */
                if (XFS_IS_CORRUPT(mp, stat != 1)) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        goto error0;
                }
                if ((error = xfs_btree_new_iroot(cur, flags, &stat)))
                        goto error0;
                if (stat == 0) {
                        xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
                        return -ENOSPC;
                }
                cur->bc_bmap.allocated = 0;
                xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
        }
        return 0;
error0:
        xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
        return error;
}

/*
 * Called from xfs_bmap_add_attrfork to handle extents format files.
 */
STATIC int                                      /* error */
xfs_bmap_add_attrfork_extents(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode pointer */
        int                     *flags)         /* inode logging flags */
{
        struct xfs_btree_cur    *cur;           /* bmap btree cursor */
        int                     error;          /* error return value */

        if (ip->i_df.if_nextents * sizeof(struct xfs_bmbt_rec) <=
            xfs_inode_data_fork_size(ip))
                return 0;
        cur = NULL;
        error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0, flags,
                                          XFS_DATA_FORK);
        if (cur) {
                cur->bc_bmap.allocated = 0;
                xfs_btree_del_cursor(cur, error);
        }
        return error;
}

/*
 * Called from xfs_bmap_add_attrfork to handle local format files. Each
 * different data fork content type needs a different callout to do the
 * conversion. Some are basic and only require special block initialisation
 * callouts for the data formating, others (directories) are so specialised they
 * handle everything themselves.
 *
 * XXX (dgc): investigate whether directory conversion can use the generic
 * formatting callout. It should be possible - it's just a very complex
 * formatter.
 */
STATIC int                                      /* error */
xfs_bmap_add_attrfork_local(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode pointer */
        int                     *flags)         /* inode logging flags */
{
        struct xfs_da_args      dargs;          /* args for dir/attr code */

        if (ip->i_df.if_bytes <= xfs_inode_data_fork_size(ip))
                return 0;

        if (S_ISDIR(VFS_I(ip)->i_mode)) {
                memset(&dargs, 0, sizeof(dargs));
                dargs.geo = ip->i_mount->m_dir_geo;
                dargs.dp = ip;
                dargs.total = dargs.geo->fsbcount;
                dargs.whichfork = XFS_DATA_FORK;
                dargs.trans = tp;
                dargs.owner = ip->i_ino;
                return xfs_dir2_sf_to_block(&dargs);
        }

        if (S_ISLNK(VFS_I(ip)->i_mode))
                return xfs_bmap_local_to_extents(tp, ip, 1, flags,
                                XFS_DATA_FORK, xfs_symlink_local_to_remote,
                                NULL);

        /* should only be called for types that support local format data */
        ASSERT(0);
        xfs_bmap_mark_sick(ip, XFS_ATTR_FORK);
        return -EFSCORRUPTED;
}

/*
 * Set an inode attr fork offset based on the format of the data fork.
 */
static int
xfs_bmap_set_attrforkoff(
        struct xfs_inode        *ip,
        int                     size)
{
        int                     default_size = xfs_default_attroffset(ip) >> 3;

        switch (ip->i_df.if_format) {
        case XFS_DINODE_FMT_DEV:
                ip->i_forkoff = default_size;
                break;
        case XFS_DINODE_FMT_LOCAL:
        case XFS_DINODE_FMT_EXTENTS:
        case XFS_DINODE_FMT_BTREE:
                ip->i_forkoff = xfs_attr_shortform_bytesfit(ip, size);
                if (!ip->i_forkoff)
                        ip->i_forkoff = default_size;
                break;
        default:
                ASSERT(0);
                return -EINVAL;
        }

        return 0;
}

/*
 * Convert inode from non-attributed to attributed.  Caller must hold the
 * ILOCK_EXCL and the file cannot have an attr fork.
 */
int                                             /* error code */
xfs_bmap_add_attrfork(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,            /* incore inode pointer */
        int                     size,           /* space new attribute needs */
        int                     rsvd)           /* xact may use reserved blks */
{
        struct xfs_mount        *mp = tp->t_mountp;
        int                     logflags;       /* logging flags */
        int                     error;          /* error return value */

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        if (!xfs_is_metadir_inode(ip))
                ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
        ASSERT(!xfs_inode_has_attr_fork(ip));

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        error = xfs_bmap_set_attrforkoff(ip, size);
        if (error)
                return error;

        xfs_ifork_init_attr(ip, XFS_DINODE_FMT_EXTENTS, 0);
        logflags = 0;
        switch (ip->i_df.if_format) {
        case XFS_DINODE_FMT_LOCAL:
                error = xfs_bmap_add_attrfork_local(tp, ip, &logflags);
                break;
        case XFS_DINODE_FMT_EXTENTS:
                error = xfs_bmap_add_attrfork_extents(tp, ip, &logflags);
                break;
        case XFS_DINODE_FMT_BTREE:
                error = xfs_bmap_add_attrfork_btree(tp, ip, &logflags);
                break;
        default:
                error = 0;
                break;
        }
        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        if (error)
                return error;
        if (!xfs_has_attr(mp)) {
                bool log_sb = false;

                spin_lock(&mp->m_sb_lock);
                if (!xfs_has_attr(mp)) {
                        xfs_add_attr(mp);
                        xfs_add_attr2(mp);
                        log_sb = true;
                }
                spin_unlock(&mp->m_sb_lock);
                if (log_sb)
                        xfs_log_sb(tp);
        }

        return 0;
}

/*
 * Internal and external extent tree search functions.
 */

struct xfs_iread_state {
        struct xfs_iext_cursor  icur;
        xfs_extnum_t            loaded;
};

int
xfs_bmap_complain_bad_rec(
        struct xfs_inode                *ip,
        int                             whichfork,
        xfs_failaddr_t                  fa,
        const struct xfs_bmbt_irec      *irec)
{
        struct xfs_mount                *mp = ip->i_mount;
        const char                      *forkname;

        switch (whichfork) {
        case XFS_DATA_FORK:     forkname = "data"; break;
        case XFS_ATTR_FORK:     forkname = "attr"; break;
        case XFS_COW_FORK:      forkname = "CoW"; break;
        default:                forkname = "???"; break;
        }

        xfs_warn(mp,
 "Bmap BTree record corruption in inode 0x%llx %s fork detected at %pS!",
                                ip->i_ino, forkname, fa);
        xfs_warn(mp,
                "Offset 0x%llx, start block 0x%llx, block count 0x%llx state 0x%x",
                irec->br_startoff, irec->br_startblock, irec->br_blockcount,
                irec->br_state);

        return -EFSCORRUPTED;
}

/* Stuff every bmbt record from this block into the incore extent map. */
static int
xfs_iread_bmbt_block(
        struct xfs_btree_cur    *cur,
        int                     level,
        void                    *priv)
{
        struct xfs_iread_state  *ir = priv;
        struct xfs_mount        *mp = cur->bc_mp;
        struct xfs_inode        *ip = cur->bc_ino.ip;
        struct xfs_btree_block  *block;
        struct xfs_buf          *bp;
        struct xfs_bmbt_rec     *frp;
        xfs_extnum_t            num_recs;
        xfs_extnum_t            j;
        int                     whichfork = cur->bc_ino.whichfork;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);

        block = xfs_btree_get_block(cur, level, &bp);

        /* Abort if we find more records than nextents. */
        num_recs = xfs_btree_get_numrecs(block);
        if (unlikely(ir->loaded + num_recs > ifp->if_nextents)) {
                xfs_warn(ip->i_mount, "corrupt dinode %llu, (btree extents).",
                                (unsigned long long)ip->i_ino);
                xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, block,
                                sizeof(*block), __this_address);
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        /* Copy records into the incore cache. */
        frp = xfs_bmbt_rec_addr(mp, block, 1);
        for (j = 0; j < num_recs; j++, frp++, ir->loaded++) {
                struct xfs_bmbt_irec    new;
                xfs_failaddr_t          fa;

                xfs_bmbt_disk_get_all(frp, &new);
                fa = xfs_bmap_validate_extent(ip, whichfork, &new);
                if (fa) {
                        xfs_inode_verifier_error(ip, -EFSCORRUPTED,
                                        "xfs_iread_extents(2)", frp,
                                        sizeof(*frp), fa);
                        xfs_bmap_mark_sick(ip, whichfork);
                        return xfs_bmap_complain_bad_rec(ip, whichfork, fa,
                                        &new);
                }
                xfs_iext_insert(ip, &ir->icur, &new,
                                xfs_bmap_fork_to_state(whichfork));
                trace_xfs_read_extent(ip, &ir->icur,
                                xfs_bmap_fork_to_state(whichfork), _THIS_IP_);
                xfs_iext_next(ifp, &ir->icur);
        }

        return 0;
}

/*
 * Read in extents from a btree-format inode.
 */
int
xfs_iread_extents(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork)
{
        struct xfs_iread_state  ir;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_btree_cur    *cur;
        int                     error;

        if (!xfs_need_iread_extents(ifp))
                return 0;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);

        ir.loaded = 0;
        xfs_iext_first(ifp, &ir.icur);
        cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
        error = xfs_btree_visit_blocks(cur, xfs_iread_bmbt_block,
                        XFS_BTREE_VISIT_RECORDS, &ir);
        xfs_btree_del_cursor(cur, error);
        if (error)
                goto out;

        if (XFS_IS_CORRUPT(mp, ir.loaded != ifp->if_nextents)) {
                xfs_bmap_mark_sick(ip, whichfork);
                error = -EFSCORRUPTED;
                goto out;
        }
        ASSERT(ir.loaded == xfs_iext_count(ifp));
        /*
         * Use release semantics so that we can use acquire semantics in
         * xfs_need_iread_extents and be guaranteed to see a valid mapping tree
         * after that load.
         */
        smp_store_release(&ifp->if_needextents, 0);
        return 0;
out:
        if (xfs_metadata_is_sick(error))
                xfs_bmap_mark_sick(ip, whichfork);
        xfs_iext_destroy(ifp);
        return error;
}

/*
 * Returns the relative block number of the first unused block(s) in the given
 * fork with at least "len" logically contiguous blocks free.  This is the
 * lowest-address hole if the fork has holes, else the first block past the end
 * of fork.  Return 0 if the fork is currently local (in-inode).
 */
int                                             /* error */
xfs_bmap_first_unused(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode */
        xfs_extlen_t            len,            /* size of hole to find */
        xfs_fileoff_t           *first_unused,  /* unused block */
        int                     whichfork)      /* data or attr fork */
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec    got;
        struct xfs_iext_cursor  icur;
        xfs_fileoff_t           lastaddr = 0;
        xfs_fileoff_t           lowest, max;
        int                     error;

        if (ifp->if_format == XFS_DINODE_FMT_LOCAL) {
                *first_unused = 0;
                return 0;
        }

        ASSERT(xfs_ifork_has_extents(ifp));

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        lowest = max = *first_unused;
        for_each_xfs_iext(ifp, &icur, &got) {
                /*
                 * See if the hole before this extent will work.
                 */
                if (got.br_startoff >= lowest + len &&
                    got.br_startoff - max >= len)
                        break;
                lastaddr = got.br_startoff + got.br_blockcount;
                max = XFS_FILEOFF_MAX(lastaddr, lowest);
        }

        *first_unused = max;
        return 0;
}

/*
 * Returns the file-relative block number of the last block - 1 before
 * last_block (input value) in the file.
 * This is not based on i_size, it is based on the extent records.
 * Returns 0 for local files, as they do not have extent records.
 */
int                                             /* error */
xfs_bmap_last_before(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode */
        xfs_fileoff_t           *last_block,    /* last block */
        int                     whichfork)      /* data or attr fork */
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec    got;
        struct xfs_iext_cursor  icur;
        int                     error;

        switch (ifp->if_format) {
        case XFS_DINODE_FMT_LOCAL:
                *last_block = 0;
                return 0;
        case XFS_DINODE_FMT_BTREE:
        case XFS_DINODE_FMT_EXTENTS:
                break;
        default:
                ASSERT(0);
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
                *last_block = 0;
        return 0;
}

int
xfs_bmap_last_extent(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *rec,
        int                     *is_empty)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_iext_cursor  icur;
        int                     error;

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        xfs_iext_last(ifp, &icur);
        if (!xfs_iext_get_extent(ifp, &icur, rec))
                *is_empty = 1;
        else
                *is_empty = 0;
        return 0;
}

/*
 * Check the last inode extent to determine whether this allocation will result
 * in blocks being allocated at the end of the file. When we allocate new data
 * blocks at the end of the file which do not start at the previous data block,
 * we will try to align the new blocks at stripe unit boundaries.
 *
 * Returns 1 in bma->aeof if the file (fork) is empty as any new write will be
 * at, or past the EOF.
 */
STATIC int
xfs_bmap_isaeof(
        struct xfs_bmalloca     *bma,
        int                     whichfork)
{
        struct xfs_bmbt_irec    rec;
        int                     is_empty;
        int                     error;

        bma->aeof = false;
        error = xfs_bmap_last_extent(NULL, bma->ip, whichfork, &rec,
                                     &is_empty);
        if (error)
                return error;

        if (is_empty) {
                bma->aeof = true;
                return 0;
        }

        /*
         * Check if we are allocation or past the last extent, or at least into
         * the last delayed allocated extent.
         */
        bma->aeof = bma->offset >= rec.br_startoff + rec.br_blockcount ||
                (bma->offset >= rec.br_startoff &&
                 isnullstartblock(rec.br_startblock));
        return 0;
}

/*
 * Returns the file-relative block number of the first block past eof in
 * the file.  This is not based on i_size, it is based on the extent records.
 * Returns 0 for local files, as they do not have extent records.
 */
int
xfs_bmap_last_offset(
        struct xfs_inode        *ip,
        xfs_fileoff_t           *last_block,
        int                     whichfork)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec    rec;
        int                     is_empty;
        int                     error;

        *last_block = 0;

        if (ifp->if_format == XFS_DINODE_FMT_LOCAL)
                return 0;

        if (XFS_IS_CORRUPT(ip->i_mount, !xfs_ifork_has_extents(ifp))) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        error = xfs_bmap_last_extent(NULL, ip, whichfork, &rec, &is_empty);
        if (error || is_empty)
                return error;

        *last_block = rec.br_startoff + rec.br_blockcount;
        return 0;
}

/*
 * Extent tree manipulation functions used during allocation.
 */

static inline bool
xfs_bmap_same_rtgroup(
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *left,
        struct xfs_bmbt_irec    *right)
{
        struct xfs_mount        *mp = ip->i_mount;

        if (xfs_ifork_is_realtime(ip, whichfork) && xfs_has_rtgroups(mp)) {
                if (xfs_rtb_to_rgno(mp, left->br_startblock) !=
                    xfs_rtb_to_rgno(mp, right->br_startblock))
                        return false;
        }

        return true;
}

/*
 * Convert a delayed allocation to a real allocation.
 */
STATIC int                              /* error */
xfs_bmap_add_extent_delay_real(
        struct xfs_bmalloca     *bma,
        int                     whichfork)
{
        struct xfs_mount        *mp = bma->ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(bma->ip, whichfork);
        struct xfs_bmbt_irec    *new = &bma->got;
        int                     error;  /* error return value */
        int                     i;      /* temp state */
        xfs_fileoff_t           new_endoff;     /* end offset of new entry */
        xfs_bmbt_irec_t         r[3];   /* neighbor extent entries */
                                        /* left is 0, right is 1, prev is 2 */
        int                     rval=0; /* return value (logging flags) */
        uint32_t                state = xfs_bmap_fork_to_state(whichfork);
        xfs_filblks_t           da_new; /* new count del alloc blocks used */
        xfs_filblks_t           da_old; /* old count del alloc blocks used */
        xfs_filblks_t           temp=0; /* value for da_new calculations */
        int                     tmp_rval;       /* partial logging flags */
        struct xfs_bmbt_irec    old;

        ASSERT(whichfork != XFS_ATTR_FORK);
        ASSERT(!isnullstartblock(new->br_startblock));
        ASSERT(!bma->cur || (bma->cur->bc_flags & XFS_BTREE_BMBT_WASDEL));

        XFS_STATS_INC(mp, xs_add_exlist);

#define LEFT            r[0]
#define RIGHT           r[1]
#define PREV            r[2]

        /*
         * Set up a bunch of variables to make the tests simpler.
         */
        xfs_iext_get_extent(ifp, &bma->icur, &PREV);
        new_endoff = new->br_startoff + new->br_blockcount;
        ASSERT(isnullstartblock(PREV.br_startblock));
        ASSERT(PREV.br_startoff <= new->br_startoff);
        ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);

        da_old = startblockval(PREV.br_startblock);
        da_new = 0;

        /*
         * Set flags determining what part of the previous delayed allocation
         * extent is being replaced by a real allocation.
         */
        if (PREV.br_startoff == new->br_startoff)
                state |= BMAP_LEFT_FILLING;
        if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
                state |= BMAP_RIGHT_FILLING;

        /*
         * Check and set flags if this segment has a left neighbor.
         * Don't set contiguous if the combined extent would be too large.
         */
        if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
                state |= BMAP_LEFT_VALID;
                if (isnullstartblock(LEFT.br_startblock))
                        state |= BMAP_LEFT_DELAY;
        }

        if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
            LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
            LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
            LEFT.br_state == new->br_state &&
            LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            xfs_bmap_same_rtgroup(bma->ip, whichfork, &LEFT, new))
                state |= BMAP_LEFT_CONTIG;

        /*
         * Check and set flags if this segment has a right neighbor.
         * Don't set contiguous if the combined extent would be too large.
         * Also check for all-three-contiguous being too large.
         */
        if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
                state |= BMAP_RIGHT_VALID;
                if (isnullstartblock(RIGHT.br_startblock))
                        state |= BMAP_RIGHT_DELAY;
        }

        if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
            new_endoff == RIGHT.br_startoff &&
            new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
            new->br_state == RIGHT.br_state &&
            new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
                       BMAP_RIGHT_FILLING)) !=
                      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
                       BMAP_RIGHT_FILLING) ||
             LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
                        <= XFS_MAX_BMBT_EXTLEN) &&
            xfs_bmap_same_rtgroup(bma->ip, whichfork, new, &RIGHT))
                state |= BMAP_RIGHT_CONTIG;

        error = 0;
        /*
         * Switch out based on the FILLING and CONTIG state bits.
         */
        switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
                         BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
             BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Filling in all of a previously delayed allocation extent.
                 * The left and right neighbors are both contiguous with new.
                 */
                LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;

                xfs_iext_remove(bma->ip, &bma->icur, state);
                xfs_iext_remove(bma->ip, &bma->icur, state);
                xfs_iext_prev(ifp, &bma->icur);
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
                ifp->if_nextents--;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_delete(bma->cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_decrement(bma->cur, 0, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(bma->cur, &LEFT);
                        if (error)
                                goto done;
                }
                ASSERT(da_new <= da_old);
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
                /*
                 * Filling in all of a previously delayed allocation extent.
                 * The left neighbor is contiguous, the right is not.
                 */
                old = LEFT;
                LEFT.br_blockcount += PREV.br_blockcount;

                xfs_iext_remove(bma->ip, &bma->icur, state);
                xfs_iext_prev(ifp, &bma->icur);
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);

                if (bma->cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(bma->cur, &LEFT);
                        if (error)
                                goto done;
                }
                ASSERT(da_new <= da_old);
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Filling in all of a previously delayed allocation extent.
                 * The right neighbor is contiguous, the left is not. Take care
                 * with delay -> unwritten extent allocation here because the
                 * delalloc record we are overwriting is always written.
                 */
                PREV.br_startblock = new->br_startblock;
                PREV.br_blockcount += RIGHT.br_blockcount;
                PREV.br_state = new->br_state;

                xfs_iext_next(ifp, &bma->icur);
                xfs_iext_remove(bma->ip, &bma->icur, state);
                xfs_iext_prev(ifp, &bma->icur);
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);

                if (bma->cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(bma->cur, &PREV);
                        if (error)
                                goto done;
                }
                ASSERT(da_new <= da_old);
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
                /*
                 * Filling in all of a previously delayed allocation extent.
                 * Neither the left nor right neighbors are contiguous with
                 * the new one.
                 */
                PREV.br_startblock = new->br_startblock;
                PREV.br_state = new->br_state;
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
                ifp->if_nextents++;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_insert(bma->cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }
                ASSERT(da_new <= da_old);
                break;

        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
                /*
                 * Filling in the first part of a previous delayed allocation.
                 * The left neighbor is contiguous.
                 */
                old = LEFT;
                temp = PREV.br_blockcount - new->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
                                startblockval(PREV.br_startblock));

                LEFT.br_blockcount += new->br_blockcount;

                PREV.br_blockcount = temp;
                PREV.br_startoff += new->br_blockcount;
                PREV.br_startblock = nullstartblock(da_new);

                xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
                xfs_iext_prev(ifp, &bma->icur);
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);

                if (bma->cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(bma->cur, &LEFT);
                        if (error)
                                goto done;
                }
                ASSERT(da_new <= da_old);
                break;

        case BMAP_LEFT_FILLING:
                /*
                 * Filling in the first part of a previous delayed allocation.
                 * The left neighbor is not contiguous.
                 */
                xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
                ifp->if_nextents++;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_insert(bma->cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }

                if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
                        error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
                                        &bma->cur, 1, &tmp_rval, whichfork);
                        rval |= tmp_rval;
                        if (error)
                                goto done;
                }

                temp = PREV.br_blockcount - new->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
                        startblockval(PREV.br_startblock) -
                        (bma->cur ? bma->cur->bc_bmap.allocated : 0));

                PREV.br_startoff = new_endoff;
                PREV.br_blockcount = temp;
                PREV.br_startblock = nullstartblock(da_new);
                xfs_iext_next(ifp, &bma->icur);
                xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
                xfs_iext_prev(ifp, &bma->icur);
                break;

        case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Filling in the last part of a previous delayed allocation.
                 * The right neighbor is contiguous with the new allocation.
                 */
                old = RIGHT;
                RIGHT.br_startoff = new->br_startoff;
                RIGHT.br_startblock = new->br_startblock;
                RIGHT.br_blockcount += new->br_blockcount;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(bma->cur, &RIGHT);
                        if (error)
                                goto done;
                }

                temp = PREV.br_blockcount - new->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
                        startblockval(PREV.br_startblock));

                PREV.br_blockcount = temp;
                PREV.br_startblock = nullstartblock(da_new);

                xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
                xfs_iext_next(ifp, &bma->icur);
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
                ASSERT(da_new <= da_old);
                break;

        case BMAP_RIGHT_FILLING:
                /*
                 * Filling in the last part of a previous delayed allocation.
                 * The right neighbor is not contiguous.
                 */
                xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
                ifp->if_nextents++;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_insert(bma->cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }

                if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
                        error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
                                &bma->cur, 1, &tmp_rval, whichfork);
                        rval |= tmp_rval;
                        if (error)
                                goto done;
                }

                temp = PREV.br_blockcount - new->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
                        startblockval(PREV.br_startblock) -
                        (bma->cur ? bma->cur->bc_bmap.allocated : 0));

                PREV.br_startblock = nullstartblock(da_new);
                PREV.br_blockcount = temp;
                xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
                xfs_iext_next(ifp, &bma->icur);
                ASSERT(da_new <= da_old);
                break;

        case 0:
                /*
                 * Filling in the middle part of a previous delayed allocation.
                 * Contiguity is impossible here.
                 * This case is avoided almost all the time.
                 *
                 * We start with a delayed allocation:
                 *
                 * +ddddddddddddddddddddddddddddddddddddddddddddddddddddddd+
                 *  PREV @ idx
                 *
                 * and we are allocating:
                 *                     +rrrrrrrrrrrrrrrrr+
                 *                            new
                 *
                 * and we set it up for insertion as:
                 * +ddddddddddddddddddd+rrrrrrrrrrrrrrrrr+ddddddddddddddddd+
                 *                            new
                 *  PREV @ idx          LEFT              RIGHT
                 *                      inserted at idx + 1
                 */
                old = PREV;

                /* LEFT is the new middle */
                LEFT = *new;

                /* RIGHT is the new right */
                RIGHT.br_state = PREV.br_state;
                RIGHT.br_startoff = new_endoff;
                RIGHT.br_blockcount =
                        PREV.br_startoff + PREV.br_blockcount - new_endoff;
                RIGHT.br_startblock =
                        nullstartblock(xfs_bmap_worst_indlen(bma->ip,
                                        RIGHT.br_blockcount));

                /* truncate PREV */
                PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
                PREV.br_startblock =
                        nullstartblock(xfs_bmap_worst_indlen(bma->ip,
                                        PREV.br_blockcount));
                xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);

                xfs_iext_next(ifp, &bma->icur);
                xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
                xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
                ifp->if_nextents++;

                if (bma->cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_insert(bma->cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(bma->cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }

                if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
                        error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
                                        &bma->cur, 1, &tmp_rval, whichfork);
                        rval |= tmp_rval;
                        if (error)
                                goto done;
                }

                da_new = startblockval(PREV.br_startblock) +
                         startblockval(RIGHT.br_startblock);
                break;

        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
        case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
        case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_LEFT_CONTIG:
        case BMAP_RIGHT_CONTIG:
                /*
                 * These cases are all impossible.
                 */
                ASSERT(0);
        }

        /* add reverse mapping unless caller opted out */
        if (!(bma->flags & XFS_BMAPI_NORMAP))
                xfs_rmap_map_extent(bma->tp, bma->ip, whichfork, new);

        /* convert to a btree if necessary */
        if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
                int     tmp_logflags;   /* partial log flag return val */

                ASSERT(bma->cur == NULL);
                error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
                                &bma->cur, da_old > 0, &tmp_logflags,
                                whichfork);
                bma->logflags |= tmp_logflags;
                if (error)
                        goto done;
        }

        if (da_new != da_old)
                xfs_mod_delalloc(bma->ip, 0, (int64_t)da_new - da_old);

        if (bma->cur) {
                da_new += bma->cur->bc_bmap.allocated;
                bma->cur->bc_bmap.allocated = 0;
        }

        /* adjust for changes in reserved delayed indirect blocks */
        if (da_new < da_old)
                xfs_add_fdblocks(mp, da_old - da_new);
        else if (da_new > da_old)
                error = xfs_dec_fdblocks(mp, da_new - da_old, true);

        xfs_bmap_check_leaf_extents(bma->cur, bma->ip, whichfork);
done:
        if (whichfork != XFS_COW_FORK)
                bma->logflags |= rval;
        return error;
#undef  LEFT
#undef  RIGHT
#undef  PREV
}

/*
 * Convert an unwritten allocation to a real allocation or vice versa.
 */
int                                     /* error */
xfs_bmap_add_extent_unwritten_real(
        struct xfs_trans        *tp,
        xfs_inode_t             *ip,    /* incore inode pointer */
        int                     whichfork,
        struct xfs_iext_cursor  *icur,
        struct xfs_btree_cur    **curp, /* if *curp is null, not a btree */
        xfs_bmbt_irec_t         *new,   /* new data to add to file extents */
        int                     *logflagsp) /* inode logging flags */
{
        struct xfs_btree_cur    *cur;   /* btree cursor */
        int                     error;  /* error return value */
        int                     i;      /* temp state */
        struct xfs_ifork        *ifp;   /* inode fork pointer */
        xfs_fileoff_t           new_endoff;     /* end offset of new entry */
        xfs_bmbt_irec_t         r[3];   /* neighbor extent entries */
                                        /* left is 0, right is 1, prev is 2 */
        int                     rval=0; /* return value (logging flags) */
        uint32_t                state = xfs_bmap_fork_to_state(whichfork);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_bmbt_irec    old;

        *logflagsp = 0;

        cur = *curp;
        ifp = xfs_ifork_ptr(ip, whichfork);

        ASSERT(!isnullstartblock(new->br_startblock));

        XFS_STATS_INC(mp, xs_add_exlist);

#define LEFT            r[0]
#define RIGHT           r[1]
#define PREV            r[2]

        /*
         * Set up a bunch of variables to make the tests simpler.
         */
        error = 0;
        xfs_iext_get_extent(ifp, icur, &PREV);
        ASSERT(new->br_state != PREV.br_state);
        new_endoff = new->br_startoff + new->br_blockcount;
        ASSERT(PREV.br_startoff <= new->br_startoff);
        ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);

        /*
         * Set flags determining what part of the previous oldext allocation
         * extent is being replaced by a newext allocation.
         */
        if (PREV.br_startoff == new->br_startoff)
                state |= BMAP_LEFT_FILLING;
        if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
                state |= BMAP_RIGHT_FILLING;

        /*
         * Check and set flags if this segment has a left neighbor.
         * Don't set contiguous if the combined extent would be too large.
         */
        if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
                state |= BMAP_LEFT_VALID;
                if (isnullstartblock(LEFT.br_startblock))
                        state |= BMAP_LEFT_DELAY;
        }

        if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
            LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
            LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
            LEFT.br_state == new->br_state &&
            LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            xfs_bmap_same_rtgroup(ip, whichfork, &LEFT, new))
                state |= BMAP_LEFT_CONTIG;

        /*
         * Check and set flags if this segment has a right neighbor.
         * Don't set contiguous if the combined extent would be too large.
         * Also check for all-three-contiguous being too large.
         */
        if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
                state |= BMAP_RIGHT_VALID;
                if (isnullstartblock(RIGHT.br_startblock))
                        state |= BMAP_RIGHT_DELAY;
        }

        if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
            new_endoff == RIGHT.br_startoff &&
            new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
            new->br_state == RIGHT.br_state &&
            new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
                       BMAP_RIGHT_FILLING)) !=
                      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
                       BMAP_RIGHT_FILLING) ||
             LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
                        <= XFS_MAX_BMBT_EXTLEN) &&
            xfs_bmap_same_rtgroup(ip, whichfork, new, &RIGHT))
                state |= BMAP_RIGHT_CONTIG;

        /*
         * Switch out based on the FILLING and CONTIG state bits.
         */
        switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
                         BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
             BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Setting all of a previous oldext extent to newext.
                 * The left and right neighbors are both contiguous with new.
                 */
                LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;

                xfs_iext_remove(ip, icur, state);
                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &LEFT);
                ifp->if_nextents -= 2;
                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_delete(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_decrement(cur, 0, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_delete(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_decrement(cur, 0, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &LEFT);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
                /*
                 * Setting all of a previous oldext extent to newext.
                 * The left neighbor is contiguous, the right is not.
                 */
                LEFT.br_blockcount += PREV.br_blockcount;

                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &LEFT);
                ifp->if_nextents--;
                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &PREV, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_delete(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_decrement(cur, 0, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &LEFT);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Setting all of a previous oldext extent to newext.
                 * The right neighbor is contiguous, the left is not.
                 */
                PREV.br_blockcount += RIGHT.br_blockcount;
                PREV.br_state = new->br_state;

                xfs_iext_next(ifp, icur);
                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &PREV);
                ifp->if_nextents--;

                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_delete(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_decrement(cur, 0, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
                /*
                 * Setting all of a previous oldext extent to newext.
                 * Neither the left nor right neighbors are contiguous with
                 * the new one.
                 */
                PREV.br_state = new->br_state;
                xfs_iext_update_extent(ip, state, icur, &PREV);

                if (cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
                /*
                 * Setting the first part of a previous oldext extent to newext.
                 * The left neighbor is contiguous.
                 */
                LEFT.br_blockcount += new->br_blockcount;

                old = PREV;
                PREV.br_startoff += new->br_blockcount;
                PREV.br_startblock += new->br_blockcount;
                PREV.br_blockcount -= new->br_blockcount;

                xfs_iext_update_extent(ip, state, icur, &PREV);
                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &LEFT);

                if (cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                        error = xfs_btree_decrement(cur, 0, &i);
                        if (error)
                                goto done;
                        error = xfs_bmbt_update(cur, &LEFT);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_FILLING:
                /*
                 * Setting the first part of a previous oldext extent to newext.
                 * The left neighbor is not contiguous.
                 */
                old = PREV;
                PREV.br_startoff += new->br_blockcount;
                PREV.br_startblock += new->br_blockcount;
                PREV.br_blockcount -= new->br_blockcount;

                xfs_iext_update_extent(ip, state, icur, &PREV);
                xfs_iext_insert(ip, icur, new, state);
                ifp->if_nextents++;

                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                        cur->bc_rec.b = *new;
                        if ((error = xfs_btree_insert(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }
                break;

        case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
                /*
                 * Setting the last part of a previous oldext extent to newext.
                 * The right neighbor is contiguous with the new allocation.
                 */
                old = PREV;
                PREV.br_blockcount -= new->br_blockcount;

                RIGHT.br_startoff = new->br_startoff;
                RIGHT.br_startblock = new->br_startblock;
                RIGHT.br_blockcount += new->br_blockcount;

                xfs_iext_update_extent(ip, state, icur, &PREV);
                xfs_iext_next(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &RIGHT);

                if (cur == NULL)
                        rval = XFS_ILOG_DEXT;
                else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                        error = xfs_btree_increment(cur, 0, &i);
                        if (error)
                                goto done;
                        error = xfs_bmbt_update(cur, &RIGHT);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_RIGHT_FILLING:
                /*
                 * Setting the last part of a previous oldext extent to newext.
                 * The right neighbor is not contiguous.
                 */
                old = PREV;
                PREV.br_blockcount -= new->br_blockcount;

                xfs_iext_update_extent(ip, state, icur, &PREV);
                xfs_iext_next(ifp, icur);
                xfs_iext_insert(ip, icur, new, state);
                ifp->if_nextents++;

                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &PREV);
                        if (error)
                                goto done;
                        error = xfs_bmbt_lookup_eq(cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        if ((error = xfs_btree_insert(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }
                break;

        case 0:
                /*
                 * Setting the middle part of a previous oldext extent to
                 * newext.  Contiguity is impossible here.
                 * One extent becomes three extents.
                 */
                old = PREV;
                PREV.br_blockcount = new->br_startoff - PREV.br_startoff;

                r[0] = *new;
                r[1].br_startoff = new_endoff;
                r[1].br_blockcount =
                        old.br_startoff + old.br_blockcount - new_endoff;
                r[1].br_startblock = new->br_startblock + new->br_blockcount;
                r[1].br_state = PREV.br_state;

                xfs_iext_update_extent(ip, state, icur, &PREV);
                xfs_iext_next(ifp, icur);
                xfs_iext_insert(ip, icur, &r[1], state);
                xfs_iext_insert(ip, icur, &r[0], state);
                ifp->if_nextents += 2;

                if (cur == NULL)
                        rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
                else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        /* new right extent - oldext */
                        error = xfs_bmbt_update(cur, &r[1]);
                        if (error)
                                goto done;
                        /* new left extent - oldext */
                        cur->bc_rec.b = PREV;
                        if ((error = xfs_btree_insert(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        /*
                         * Reset the cursor to the position of the new extent
                         * we are about to insert as we can't trust it after
                         * the previous insert.
                         */
                        error = xfs_bmbt_lookup_eq(cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        /* new middle extent - newext */
                        if ((error = xfs_btree_insert(cur, &i)))
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }
                break;

        case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
        case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
        case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
        case BMAP_LEFT_CONTIG:
        case BMAP_RIGHT_CONTIG:
                /*
                 * These cases are all impossible.
                 */
                ASSERT(0);
        }

        /* update reverse mappings */
        xfs_rmap_convert_extent(mp, tp, ip, whichfork, new);

        /* convert to a btree if necessary */
        if (xfs_bmap_needs_btree(ip, whichfork)) {
                int     tmp_logflags;   /* partial log flag return val */

                ASSERT(cur == NULL);
                error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
                                &tmp_logflags, whichfork);
                *logflagsp |= tmp_logflags;
                if (error)
                        goto done;
        }

        /* clear out the allocated field, done with it now in any case. */
        if (cur) {
                cur->bc_bmap.allocated = 0;
                *curp = cur;
        }

        xfs_bmap_check_leaf_extents(*curp, ip, whichfork);
done:
        *logflagsp |= rval;
        return error;
#undef  LEFT
#undef  RIGHT
#undef  PREV
}

/*
 * Convert a hole to a real allocation.
 */
STATIC int                              /* error */
xfs_bmap_add_extent_hole_real(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_iext_cursor  *icur,
        struct xfs_btree_cur    **curp,
        struct xfs_bmbt_irec    *new,
        int                     *logflagsp,
        uint32_t                flags)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_btree_cur    *cur = *curp;
        int                     error;  /* error return value */
        int                     i;      /* temp state */
        xfs_bmbt_irec_t         left;   /* left neighbor extent entry */
        xfs_bmbt_irec_t         right;  /* right neighbor extent entry */
        int                     rval=0; /* return value (logging flags) */
        uint32_t                state = xfs_bmap_fork_to_state(whichfork);
        struct xfs_bmbt_irec    old;

        ASSERT(!isnullstartblock(new->br_startblock));
        ASSERT(!cur || !(cur->bc_flags & XFS_BTREE_BMBT_WASDEL));

        XFS_STATS_INC(mp, xs_add_exlist);

        /*
         * Check and set flags if this segment has a left neighbor.
         */
        if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
                state |= BMAP_LEFT_VALID;
                if (isnullstartblock(left.br_startblock))
                        state |= BMAP_LEFT_DELAY;
        }

        /*
         * Check and set flags if this segment has a current value.
         * Not true if we're inserting into the "hole" at eof.
         */
        if (xfs_iext_get_extent(ifp, icur, &right)) {
                state |= BMAP_RIGHT_VALID;
                if (isnullstartblock(right.br_startblock))
                        state |= BMAP_RIGHT_DELAY;
        }

        /*
         * We're inserting a real allocation between "left" and "right".
         * Set the contiguity flags.  Don't let extents get too large.
         */
        if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
            left.br_startoff + left.br_blockcount == new->br_startoff &&
            left.br_startblock + left.br_blockcount == new->br_startblock &&
            left.br_state == new->br_state &&
            left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            xfs_bmap_same_rtgroup(ip, whichfork, &left, new))
                state |= BMAP_LEFT_CONTIG;

        if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
            new->br_startoff + new->br_blockcount == right.br_startoff &&
            new->br_startblock + new->br_blockcount == right.br_startblock &&
            new->br_state == right.br_state &&
            new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
            (!(state & BMAP_LEFT_CONTIG) ||
             left.br_blockcount + new->br_blockcount +
             right.br_blockcount <= XFS_MAX_BMBT_EXTLEN) &&
            xfs_bmap_same_rtgroup(ip, whichfork, new, &right))
                state |= BMAP_RIGHT_CONTIG;

        error = 0;
        /*
         * Select which case we're in here, and implement it.
         */
        switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
        case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
                /*
                 * New allocation is contiguous with real allocations on the
                 * left and on the right.
                 * Merge all three into a single extent record.
                 */
                left.br_blockcount += new->br_blockcount + right.br_blockcount;

                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &left);
                ifp->if_nextents--;

                if (cur == NULL) {
                        rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
                } else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, &right, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_delete(cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_decrement(cur, 0, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &left);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_LEFT_CONTIG:
                /*
                 * New allocation is contiguous with a real allocation
                 * on the left.
                 * Merge the new allocation with the left neighbor.
                 */
                old = left;
                left.br_blockcount += new->br_blockcount;

                xfs_iext_prev(ifp, icur);
                xfs_iext_update_extent(ip, state, icur, &left);

                if (cur == NULL) {
                        rval = xfs_ilog_fext(whichfork);
                } else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &left);
                        if (error)
                                goto done;
                }
                break;

        case BMAP_RIGHT_CONTIG:
                /*
                 * New allocation is contiguous with a real allocation
                 * on the right.
                 * Merge the new allocation with the right neighbor.
                 */
                old = right;

                right.br_startoff = new->br_startoff;
                right.br_startblock = new->br_startblock;
                right.br_blockcount += new->br_blockcount;
                xfs_iext_update_extent(ip, state, icur, &right);

                if (cur == NULL) {
                        rval = xfs_ilog_fext(whichfork);
                } else {
                        rval = 0;
                        error = xfs_bmbt_lookup_eq(cur, &old, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_bmbt_update(cur, &right);
                        if (error)
                                goto done;
                }
                break;

        case 0:
                /*
                 * New allocation is not contiguous with another
                 * real allocation.
                 * Insert a new entry.
                 */
                xfs_iext_insert(ip, icur, new, state);
                ifp->if_nextents++;

                if (cur == NULL) {
                        rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
                } else {
                        rval = XFS_ILOG_CORE;
                        error = xfs_bmbt_lookup_eq(cur, new, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 0)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                        error = xfs_btree_insert(cur, &i);
                        if (error)
                                goto done;
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                error = -EFSCORRUPTED;
                                goto done;
                        }
                }
                break;
        }

        /* add reverse mapping unless caller opted out */
        if (!(flags & XFS_BMAPI_NORMAP))
                xfs_rmap_map_extent(tp, ip, whichfork, new);

        /* convert to a btree if necessary */
        if (xfs_bmap_needs_btree(ip, whichfork)) {
                int     tmp_logflags;   /* partial log flag return val */

                ASSERT(cur == NULL);
                error = xfs_bmap_extents_to_btree(tp, ip, curp, 0,
                                &tmp_logflags, whichfork);
                *logflagsp |= tmp_logflags;
                cur = *curp;
                if (error)
                        goto done;
        }

        /* clear out the allocated field, done with it now in any case. */
        if (cur)
                cur->bc_bmap.allocated = 0;

        xfs_bmap_check_leaf_extents(cur, ip, whichfork);
done:
        *logflagsp |= rval;
        return error;
}

/*
 * Functions used in the extent read, allocate and remove paths
 */

/*
 * Adjust the size of the new extent based on i_extsize and rt extsize.
 */
int
xfs_bmap_extsize_align(
        xfs_mount_t     *mp,
        xfs_bmbt_irec_t *gotp,          /* next extent pointer */
        xfs_bmbt_irec_t *prevp,         /* previous extent pointer */
        xfs_extlen_t    extsz,          /* align to this extent size */
        int             rt,             /* is this a realtime inode? */
        int             eof,            /* is extent at end-of-file? */
        int             delay,          /* creating delalloc extent? */
        int             convert,        /* overwriting unwritten extent? */
        xfs_fileoff_t   *offp,          /* in/out: aligned offset */
        xfs_extlen_t    *lenp)          /* in/out: aligned length */
{
        xfs_fileoff_t   orig_off;       /* original offset */
        xfs_extlen_t    orig_alen;      /* original length */
        xfs_fileoff_t   orig_end;       /* original off+len */
        xfs_fileoff_t   nexto;          /* next file offset */
        xfs_fileoff_t   prevo;          /* previous file offset */
        xfs_fileoff_t   align_off;      /* temp for offset */
        xfs_extlen_t    align_alen;     /* temp for length */
        xfs_extlen_t    temp;           /* temp for calculations */

        if (convert)
                return 0;

        orig_off = align_off = *offp;
        orig_alen = align_alen = *lenp;
        orig_end = orig_off + orig_alen;

        /*
         * If this request overlaps an existing extent, then don't
         * attempt to perform any additional alignment.
         */
        if (!delay && !eof &&
            (orig_off >= gotp->br_startoff) &&
            (orig_end <= gotp->br_startoff + gotp->br_blockcount)) {
                return 0;
        }

        /*
         * If the file offset is unaligned vs. the extent size
         * we need to align it.  This will be possible unless
         * the file was previously written with a kernel that didn't
         * perform this alignment, or if a truncate shot us in the
         * foot.
         */
        div_u64_rem(orig_off, extsz, &temp);
        if (temp) {
                align_alen += temp;
                align_off -= temp;
        }

        /* Same adjustment for the end of the requested area. */
        temp = (align_alen % extsz);
        if (temp)
                align_alen += extsz - temp;

        /*
         * For large extent hint sizes, the aligned extent might be larger than
         * XFS_BMBT_MAX_EXTLEN. In that case, reduce the size by an extsz so
         * that it pulls the length back under XFS_BMBT_MAX_EXTLEN. The outer
         * allocation loops handle short allocation just fine, so it is safe to
         * do this. We only want to do it when we are forced to, though, because
         * it means more allocation operations are required.
         */
        while (align_alen > XFS_MAX_BMBT_EXTLEN)
                align_alen -= extsz;
        ASSERT(align_alen <= XFS_MAX_BMBT_EXTLEN);

        /*
         * If the previous block overlaps with this proposed allocation
         * then move the start forward without adjusting the length.
         */
        if (prevp->br_startoff != NULLFILEOFF) {
                if (prevp->br_startblock == HOLESTARTBLOCK)
                        prevo = prevp->br_startoff;
                else
                        prevo = prevp->br_startoff + prevp->br_blockcount;
        } else
                prevo = 0;
        if (align_off != orig_off && align_off < prevo)
                align_off = prevo;
        /*
         * If the next block overlaps with this proposed allocation
         * then move the start back without adjusting the length,
         * but not before offset 0.
         * This may of course make the start overlap previous block,
         * and if we hit the offset 0 limit then the next block
         * can still overlap too.
         */
        if (!eof && gotp->br_startoff != NULLFILEOFF) {
                if ((delay && gotp->br_startblock == HOLESTARTBLOCK) ||
                    (!delay && gotp->br_startblock == DELAYSTARTBLOCK))
                        nexto = gotp->br_startoff + gotp->br_blockcount;
                else
                        nexto = gotp->br_startoff;
        } else
                nexto = NULLFILEOFF;
        if (!eof &&
            align_off + align_alen != orig_end &&
            align_off + align_alen > nexto)
                align_off = nexto > align_alen ? nexto - align_alen : 0;
        /*
         * If we're now overlapping the next or previous extent that
         * means we can't fit an extsz piece in this hole.  Just move
         * the start forward to the first valid spot and set
         * the length so we hit the end.
         */
        if (align_off != orig_off && align_off < prevo)
                align_off = prevo;
        if (align_off + align_alen != orig_end &&
            align_off + align_alen > nexto &&
            nexto != NULLFILEOFF) {
                ASSERT(nexto > prevo);
                align_alen = nexto - align_off;
        }

        /*
         * If realtime, and the result isn't a multiple of the realtime
         * extent size we need to remove blocks until it is.
         */
        if (rt && (temp = xfs_extlen_to_rtxmod(mp, align_alen))) {
                /*
                 * We're not covering the original request, or
                 * we won't be able to once we fix the length.
                 */
                if (orig_off < align_off ||
                    orig_end > align_off + align_alen ||
                    align_alen - temp < orig_alen)
                        return -EINVAL;
                /*
                 * Try to fix it by moving the start up.
                 */
                if (align_off + temp <= orig_off) {
                        align_alen -= temp;
                        align_off += temp;
                }
                /*
                 * Try to fix it by moving the end in.
                 */
                else if (align_off + align_alen - temp >= orig_end)
                        align_alen -= temp;
                /*
                 * Set the start to the minimum then trim the length.
                 */
                else {
                        align_alen -= orig_off - align_off;
                        align_off = orig_off;
                        align_alen -= xfs_extlen_to_rtxmod(mp, align_alen);
                }
                /*
                 * Result doesn't cover the request, fail it.
                 */
                if (orig_off < align_off || orig_end > align_off + align_alen)
                        return -EINVAL;
        } else {
                ASSERT(orig_off >= align_off);
                /* see XFS_BMBT_MAX_EXTLEN handling above */
                ASSERT(orig_end <= align_off + align_alen ||
                       align_alen + extsz > XFS_MAX_BMBT_EXTLEN);
        }

#ifdef DEBUG
        if (!eof && gotp->br_startoff != NULLFILEOFF)
                ASSERT(align_off + align_alen <= gotp->br_startoff);
        if (prevp->br_startoff != NULLFILEOFF)
                ASSERT(align_off >= prevp->br_startoff + prevp->br_blockcount);
#endif

        *lenp = align_alen;
        *offp = align_off;
        return 0;
}

static inline bool
xfs_bmap_adjacent_valid(
        struct xfs_bmalloca     *ap,
        xfs_fsblock_t           x,
        xfs_fsblock_t           y)
{
        struct xfs_mount        *mp = ap->ip->i_mount;

        if (XFS_IS_REALTIME_INODE(ap->ip) &&
            (ap->datatype & XFS_ALLOC_USERDATA)) {
                if (!xfs_has_rtgroups(mp))
                        return x < mp->m_sb.sb_rblocks;

                return xfs_rtb_to_rgno(mp, x) == xfs_rtb_to_rgno(mp, y) &&
                        xfs_rtb_to_rgno(mp, x) < mp->m_sb.sb_rgcount &&
                        xfs_rtb_to_rtx(mp, x) < mp->m_sb.sb_rgextents;

        }

        return XFS_FSB_TO_AGNO(mp, x) == XFS_FSB_TO_AGNO(mp, y) &&
                XFS_FSB_TO_AGNO(mp, x) < mp->m_sb.sb_agcount &&
                XFS_FSB_TO_AGBNO(mp, x) < mp->m_sb.sb_agblocks;
}

#define XFS_ALLOC_GAP_UNITS     4

/* returns true if ap->blkno was modified */
bool
xfs_bmap_adjacent(
        struct xfs_bmalloca     *ap)    /* bmap alloc argument struct */
{
        xfs_fsblock_t           adjust;         /* adjustment to block numbers */

        /*
         * If allocating at eof, and there's a previous real block,
         * try to use its last block as our starting point.
         */
        if (ap->eof && ap->prev.br_startoff != NULLFILEOFF &&
            !isnullstartblock(ap->prev.br_startblock) &&
            xfs_bmap_adjacent_valid(ap,
                        ap->prev.br_startblock + ap->prev.br_blockcount,
                        ap->prev.br_startblock)) {
                ap->blkno = ap->prev.br_startblock + ap->prev.br_blockcount;
                /*
                 * Adjust for the gap between prevp and us.
                 */
                adjust = ap->offset -
                        (ap->prev.br_startoff + ap->prev.br_blockcount);
                if (adjust && xfs_bmap_adjacent_valid(ap, ap->blkno + adjust,
                                ap->prev.br_startblock))
                        ap->blkno += adjust;
                return true;
        }
        /*
         * If not at eof, then compare the two neighbor blocks.
         * Figure out whether either one gives us a good starting point,
         * and pick the better one.
         */
        if (!ap->eof) {
                xfs_fsblock_t   gotbno;         /* right side block number */
                xfs_fsblock_t   gotdiff=0;      /* right side difference */
                xfs_fsblock_t   prevbno;        /* left side block number */
                xfs_fsblock_t   prevdiff=0;     /* left side difference */

                /*
                 * If there's a previous (left) block, select a requested
                 * start block based on it.
                 */
                if (ap->prev.br_startoff != NULLFILEOFF &&
                    !isnullstartblock(ap->prev.br_startblock) &&
                    (prevbno = ap->prev.br_startblock +
                               ap->prev.br_blockcount) &&
                    xfs_bmap_adjacent_valid(ap, prevbno,
                                ap->prev.br_startblock)) {
                        /*
                         * Calculate gap to end of previous block.
                         */
                        adjust = prevdiff = ap->offset -
                                (ap->prev.br_startoff +
                                 ap->prev.br_blockcount);
                        /*
                         * Figure the startblock based on the previous block's
                         * end and the gap size.
                         * Heuristic!
                         * If the gap is large relative to the piece we're
                         * allocating, or using it gives us an invalid block
                         * number, then just use the end of the previous block.
                         */
                        if (prevdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
                            xfs_bmap_adjacent_valid(ap, prevbno + prevdiff,
                                        ap->prev.br_startblock))
                                prevbno += adjust;
                        else
                                prevdiff += adjust;
                }
                /*
                 * No previous block or can't follow it, just default.
                 */
                else
                        prevbno = NULLFSBLOCK;
                /*
                 * If there's a following (right) block, select a requested
                 * start block based on it.
                 */
                if (!isnullstartblock(ap->got.br_startblock)) {
                        /*
                         * Calculate gap to start of next block.
                         */
                        adjust = gotdiff = ap->got.br_startoff - ap->offset;
                        /*
                         * Figure the startblock based on the next block's
                         * start and the gap size.
                         */
                        gotbno = ap->got.br_startblock;
                        /*
                         * Heuristic!
                         * If the gap is large relative to the piece we're
                         * allocating, or using it gives us an invalid block
                         * number, then just use the start of the next block
                         * offset by our length.
                         */
                        if (gotdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
                            xfs_bmap_adjacent_valid(ap, gotbno - gotdiff,
                                        gotbno))
                                gotbno -= adjust;
                        else if (xfs_bmap_adjacent_valid(ap, gotbno - ap->length,
                                        gotbno)) {
                                gotbno -= ap->length;
                                gotdiff += adjust - ap->length;
                        } else
                                gotdiff += adjust;
                }
                /*
                 * No next block, just default.
                 */
                else
                        gotbno = NULLFSBLOCK;
                /*
                 * If both valid, pick the better one, else the only good
                 * one, else ap->blkno is already set (to 0 or the inode block).
                 */
                if (prevbno != NULLFSBLOCK && gotbno != NULLFSBLOCK) {
                        ap->blkno = prevdiff <= gotdiff ? prevbno : gotbno;
                        return true;
                }
                if (prevbno != NULLFSBLOCK) {
                        ap->blkno = prevbno;
                        return true;
                }
                if (gotbno != NULLFSBLOCK) {
                        ap->blkno = gotbno;
                        return true;
                }
        }

        return false;
}

int
xfs_bmap_longest_free_extent(
        struct xfs_perag        *pag,
        struct xfs_trans        *tp,
        xfs_extlen_t            *blen)
{
        xfs_extlen_t            longest;
        int                     error = 0;

        if (!xfs_perag_initialised_agf(pag)) {
                error = xfs_alloc_read_agf(pag, tp, XFS_ALLOC_FLAG_TRYLOCK,
                                NULL);
                if (error)
                        return error;
        }

        longest = xfs_alloc_longest_free_extent(pag,
                                xfs_alloc_min_freelist(pag_mount(pag), pag),
                                xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
        if (*blen < longest)
                *blen = longest;

        return 0;
}

static xfs_extlen_t
xfs_bmap_select_minlen(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        xfs_extlen_t            blen)
{

        /*
         * Since we used XFS_ALLOC_FLAG_TRYLOCK in _longest_free_extent(), it is
         * possible that there is enough contiguous free space for this request.
         */
        if (blen < ap->minlen)
                return ap->minlen;

        /*
         * If the best seen length is less than the request length,
         * use the best as the minimum, otherwise we've got the maxlen we
         * were asked for.
         */
        if (blen < args->maxlen)
                return blen;
        return args->maxlen;
}

static int
xfs_bmap_btalloc_select_lengths(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        xfs_extlen_t            *blen)
{
        struct xfs_mount        *mp = args->mp;
        struct xfs_perag        *pag;
        xfs_agnumber_t          agno, startag;
        int                     error = 0;

        if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
                args->total = ap->minlen;
                args->minlen = ap->minlen;
                return 0;
        }

        args->total = ap->total;
        startag = XFS_FSB_TO_AGNO(mp, ap->blkno);
        if (startag == NULLAGNUMBER)
                startag = 0;

        *blen = 0;
        for_each_perag_wrap(mp, startag, agno, pag) {
                error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
                if (error && error != -EAGAIN)
                        break;
                error = 0;
                if (*blen >= args->maxlen)
                        break;
        }
        if (pag)
                xfs_perag_rele(pag);

        args->minlen = xfs_bmap_select_minlen(ap, args, *blen);
        return error;
}

/* Update all inode and quota accounting for the allocation we just did. */
void
xfs_bmap_alloc_account(
        struct xfs_bmalloca     *ap)
{
        bool                    isrt = XFS_IS_REALTIME_INODE(ap->ip) &&
                                        !(ap->flags & XFS_BMAPI_ATTRFORK);
        uint                    fld;

        if (ap->flags & XFS_BMAPI_COWFORK) {
                /*
                 * COW fork blocks are in-core only and thus are treated as
                 * in-core quota reservation (like delalloc blocks) even when
                 * converted to real blocks. The quota reservation is not
                 * accounted to disk until blocks are remapped to the data
                 * fork. So if these blocks were previously delalloc, we
                 * already have quota reservation and there's nothing to do
                 * yet.
                 */
                if (ap->wasdel) {
                        xfs_mod_delalloc(ap->ip, -(int64_t)ap->length, 0);
                        return;
                }

                /*
                 * Otherwise, we've allocated blocks in a hole. The transaction
                 * has acquired in-core quota reservation for this extent.
                 * Rather than account these as real blocks, however, we reduce
                 * the transaction quota reservation based on the allocation.
                 * This essentially transfers the transaction quota reservation
                 * to that of a delalloc extent.
                 */
                ap->ip->i_delayed_blks += ap->length;
                xfs_trans_mod_dquot_byino(ap->tp, ap->ip, isrt ?
                                XFS_TRANS_DQ_RES_RTBLKS : XFS_TRANS_DQ_RES_BLKS,
                                -(long)ap->length);
                return;
        }

        /* data/attr fork only */
        ap->ip->i_nblocks += ap->length;
        xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
        if (ap->wasdel) {
                ap->ip->i_delayed_blks -= ap->length;
                xfs_mod_delalloc(ap->ip, -(int64_t)ap->length, 0);
                fld = isrt ? XFS_TRANS_DQ_DELRTBCOUNT : XFS_TRANS_DQ_DELBCOUNT;
        } else {
                fld = isrt ? XFS_TRANS_DQ_RTBCOUNT : XFS_TRANS_DQ_BCOUNT;
        }

        xfs_trans_mod_dquot_byino(ap->tp, ap->ip, fld, ap->length);
}

static int
xfs_bmap_compute_alignments(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args)
{
        struct xfs_mount        *mp = args->mp;
        xfs_extlen_t            align = 0; /* minimum allocation alignment */
        int                     stripe_align = 0;

        /* stripe alignment for allocation is determined by mount parameters */
        if (mp->m_swidth && xfs_has_swalloc(mp))
                stripe_align = mp->m_swidth;
        else if (mp->m_dalign)
                stripe_align = mp->m_dalign;

        if (ap->flags & XFS_BMAPI_COWFORK)
                align = xfs_get_cowextsz_hint(ap->ip);
        else if (ap->datatype & XFS_ALLOC_USERDATA)
                align = xfs_get_extsz_hint(ap->ip);

        /* Try to align start block to any minimum allocation alignment */
        if (align > 1 && (ap->flags & XFS_BMAPI_EXTSZALIGN))
                args->alignment = align;

        if (align) {
                if (xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, align, 0,
                                        ap->eof, 0, ap->conv, &ap->offset,
                                        &ap->length))
                        ASSERT(0);
                ASSERT(ap->length);
        }

        /* apply extent size hints if obtained earlier */
        if (align) {
                args->prod = align;
                div_u64_rem(ap->offset, args->prod, &args->mod);
                if (args->mod)
                        args->mod = args->prod - args->mod;
        } else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
                args->prod = 1;
                args->mod = 0;
        } else {
                args->prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
                div_u64_rem(ap->offset, args->prod, &args->mod);
                if (args->mod)
                        args->mod = args->prod - args->mod;
        }

        return stripe_align;
}

static void
xfs_bmap_process_allocated_extent(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        xfs_fileoff_t           orig_offset,
        xfs_extlen_t            orig_length)
{
        ap->blkno = args->fsbno;
        ap->length = args->len;
        /*
         * If the extent size hint is active, we tried to round the
         * caller's allocation request offset down to extsz and the
         * length up to another extsz boundary.  If we found a free
         * extent we mapped it in starting at this new offset.  If the
         * newly mapped space isn't long enough to cover any of the
         * range of offsets that was originally requested, move the
         * mapping up so that we can fill as much of the caller's
         * original request as possible.  Free space is apparently
         * very fragmented so we're unlikely to be able to satisfy the
         * hints anyway.
         */
        if (ap->length <= orig_length)
                ap->offset = orig_offset;
        else if (ap->offset + ap->length < orig_offset + orig_length)
                ap->offset = orig_offset + orig_length - ap->length;
        xfs_bmap_alloc_account(ap);
}

static int
xfs_bmap_exact_minlen_extent_alloc(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args)
{
        if (ap->minlen != 1) {
                args->fsbno = NULLFSBLOCK;
                return 0;
        }

        args->alloc_minlen_only = 1;
        args->minlen = args->maxlen = ap->minlen;
        args->total = ap->total;

        /*
         * Unlike the longest extent available in an AG, we don't track
         * the length of an AG's shortest extent.
         * XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT is a debug only knob and
         * hence we can afford to start traversing from the 0th AG since
         * we need not be concerned about a drop in performance in
         * "debug only" code paths.
         */
        ap->blkno = XFS_AGB_TO_FSB(ap->ip->i_mount, 0, 0);

        /*
         * Call xfs_bmap_btalloc_low_space here as it first does a "normal" AG
         * iteration and then drops args->total to args->minlen, which might be
         * required to find an allocation for the transaction reservation when
         * the file system is very full.
         */
        return xfs_bmap_btalloc_low_space(ap, args);
}

/*
 * If we are not low on available data blocks and we are allocating at
 * EOF, optimise allocation for contiguous file extension and/or stripe
 * alignment of the new extent.
 *
 * NOTE: ap->aeof is only set if the allocation length is >= the
 * stripe unit and the allocation offset is at the end of file.
 */
static int
xfs_bmap_btalloc_at_eof(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        xfs_extlen_t            blen,
        int                     stripe_align,
        bool                    ag_only)
{
        struct xfs_mount        *mp = args->mp;
        struct xfs_perag        *caller_pag = args->pag;
        int                     error;

        /*
         * If there are already extents in the file, and xfs_bmap_adjacent() has
         * given a better blkno, try an exact EOF block allocation to extend the
         * file as a contiguous extent. If that fails, or it's the first
         * allocation in a file, just try for a stripe aligned allocation.
         */
        if (ap->eof) {
                xfs_extlen_t    nextminlen = 0;

                /*
                 * Compute the minlen+alignment for the next case.  Set slop so
                 * that the value of minlen+alignment+slop doesn't go up between
                 * the calls.
                 */
                args->alignment = 1;
                if (blen > stripe_align && blen <= args->maxlen)
                        nextminlen = blen - stripe_align;
                else
                        nextminlen = args->minlen;
                if (nextminlen + stripe_align > args->minlen + 1)
                        args->minalignslop = nextminlen + stripe_align -
                                        args->minlen - 1;
                else
                        args->minalignslop = 0;

                if (!caller_pag)
                        args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ap->blkno));
                error = xfs_alloc_vextent_exact_bno(args, ap->blkno);
                if (!caller_pag) {
                        xfs_perag_put(args->pag);
                        args->pag = NULL;
                }
                if (error)
                        return error;

                if (args->fsbno != NULLFSBLOCK)
                        return 0;
                /*
                 * Exact allocation failed. Reset to try an aligned allocation
                 * according to the original allocation specification.
                 */
                args->alignment = stripe_align;
                args->minlen = nextminlen;
                args->minalignslop = 0;
        } else {
                /*
                 * Adjust minlen to try and preserve alignment if we
                 * can't guarantee an aligned maxlen extent.
                 */
                args->alignment = stripe_align;
                if (blen > args->alignment &&
                    blen <= args->maxlen + args->alignment)
                        args->minlen = blen - args->alignment;
                args->minalignslop = 0;
        }

        if (ag_only) {
                error = xfs_alloc_vextent_near_bno(args, ap->blkno);
        } else {
                args->pag = NULL;
                error = xfs_alloc_vextent_start_ag(args, ap->blkno);
                ASSERT(args->pag == NULL);
                args->pag = caller_pag;
        }
        if (error)
                return error;

        if (args->fsbno != NULLFSBLOCK)
                return 0;

        /*
         * Allocation failed, so turn return the allocation args to their
         * original non-aligned state so the caller can proceed on allocation
         * failure as if this function was never called.
         */
        args->alignment = 1;
        return 0;
}

/*
 * We have failed multiple allocation attempts so now are in a low space
 * allocation situation. Try a locality first full filesystem minimum length
 * allocation whilst still maintaining necessary total block reservation
 * requirements.
 *
 * If that fails, we are now critically low on space, so perform a last resort
 * allocation attempt: no reserve, no locality, blocking, minimum length, full
 * filesystem free space scan. We also indicate to future allocations in this
 * transaction that we are critically low on space so they don't waste time on
 * allocation modes that are unlikely to succeed.
 */
int
xfs_bmap_btalloc_low_space(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args)
{
        int                     error;

        if (args->minlen > ap->minlen) {
                args->minlen = ap->minlen;
                error = xfs_alloc_vextent_start_ag(args, ap->blkno);
                if (error || args->fsbno != NULLFSBLOCK)
                        return error;
        }

        /* Last ditch attempt before failure is declared. */
        args->total = ap->minlen;
        error = xfs_alloc_vextent_first_ag(args, 0);
        if (error)
                return error;
        ap->tp->t_flags |= XFS_TRANS_LOWMODE;
        return 0;
}

static int
xfs_bmap_btalloc_filestreams(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        int                     stripe_align)
{
        xfs_extlen_t            blen = 0;
        int                     error = 0;


        error = xfs_filestream_select_ag(ap, args, &blen);
        if (error)
                return error;
        ASSERT(args->pag);

        /*
         * If we are in low space mode, then optimal allocation will fail so
         * prepare for minimal allocation and jump to the low space algorithm
         * immediately.
         */
        if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
                args->minlen = ap->minlen;
                ASSERT(args->fsbno == NULLFSBLOCK);
                goto out_low_space;
        }

        args->minlen = xfs_bmap_select_minlen(ap, args, blen);
        if (ap->aeof)
                error = xfs_bmap_btalloc_at_eof(ap, args, blen, stripe_align,
                                true);

        if (!error && args->fsbno == NULLFSBLOCK)
                error = xfs_alloc_vextent_near_bno(args, ap->blkno);

out_low_space:
        /*
         * We are now done with the perag reference for the filestreams
         * association provided by xfs_filestream_select_ag(). Release it now as
         * we've either succeeded, had a fatal error or we are out of space and
         * need to do a full filesystem scan for free space which will take it's
         * own references.
         */
        xfs_perag_rele(args->pag);
        args->pag = NULL;
        if (error || args->fsbno != NULLFSBLOCK)
                return error;

        return xfs_bmap_btalloc_low_space(ap, args);
}

static int
xfs_bmap_btalloc_best_length(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        int                     stripe_align)
{
        xfs_extlen_t            blen = 0;
        int                     error;

        ap->blkno = XFS_INO_TO_FSB(args->mp, ap->ip->i_ino);
        if (!xfs_bmap_adjacent(ap))
                ap->eof = false;

        /*
         * Search for an allocation group with a single extent large enough for
         * the request.  If one isn't found, then adjust the minimum allocation
         * size to the largest space found.
         */
        error = xfs_bmap_btalloc_select_lengths(ap, args, &blen);
        if (error)
                return error;

        /*
         * Don't attempt optimal EOF allocation if previous allocations barely
         * succeeded due to being near ENOSPC. It is highly unlikely we'll get
         * optimal or even aligned allocations in this case, so don't waste time
         * trying.
         */
        if (ap->aeof && !(ap->tp->t_flags & XFS_TRANS_LOWMODE)) {
                error = xfs_bmap_btalloc_at_eof(ap, args, blen, stripe_align,
                                false);
                if (error || args->fsbno != NULLFSBLOCK)
                        return error;
        }

        error = xfs_alloc_vextent_start_ag(args, ap->blkno);
        if (error || args->fsbno != NULLFSBLOCK)
                return error;

        return xfs_bmap_btalloc_low_space(ap, args);
}

static int
xfs_bmap_btalloc(
        struct xfs_bmalloca     *ap)
{
        struct xfs_mount        *mp = ap->ip->i_mount;
        struct xfs_alloc_arg    args = {
                .tp             = ap->tp,
                .mp             = mp,
                .fsbno          = NULLFSBLOCK,
                .oinfo          = XFS_RMAP_OINFO_SKIP_UPDATE,
                .minleft        = ap->minleft,
                .wasdel         = ap->wasdel,
                .resv           = XFS_AG_RESV_NONE,
                .datatype       = ap->datatype,
                .alignment      = 1,
                .minalignslop   = 0,
        };
        xfs_fileoff_t           orig_offset;
        xfs_extlen_t            orig_length;
        int                     error;
        int                     stripe_align;

        ASSERT(ap->length);
        orig_offset = ap->offset;
        orig_length = ap->length;

        stripe_align = xfs_bmap_compute_alignments(ap, &args);

        /* Trim the allocation back to the maximum an AG can fit. */
        args.maxlen = min(ap->length, mp->m_ag_max_usable);

        if (unlikely(XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
                error = xfs_bmap_exact_minlen_extent_alloc(ap, &args);
        else if ((ap->datatype & XFS_ALLOC_USERDATA) &&
                        xfs_inode_is_filestream(ap->ip))
                error = xfs_bmap_btalloc_filestreams(ap, &args, stripe_align);
        else
                error = xfs_bmap_btalloc_best_length(ap, &args, stripe_align);
        if (error)
                return error;

        if (args.fsbno != NULLFSBLOCK) {
                xfs_bmap_process_allocated_extent(ap, &args, orig_offset,
                        orig_length);
        } else {
                ap->blkno = NULLFSBLOCK;
                ap->length = 0;
        }
        return 0;
}

/* Trim extent to fit a logical block range. */
void
xfs_trim_extent(
        struct xfs_bmbt_irec    *irec,
        xfs_fileoff_t           bno,
        xfs_filblks_t           len)
{
        xfs_fileoff_t           distance;
        xfs_fileoff_t           end = bno + len;

        if (irec->br_startoff + irec->br_blockcount <= bno ||
            irec->br_startoff >= end) {
                irec->br_blockcount = 0;
                return;
        }

        if (irec->br_startoff < bno) {
                distance = bno - irec->br_startoff;
                if (isnullstartblock(irec->br_startblock))
                        irec->br_startblock = DELAYSTARTBLOCK;
                if (irec->br_startblock != DELAYSTARTBLOCK &&
                    irec->br_startblock != HOLESTARTBLOCK)
                        irec->br_startblock += distance;
                irec->br_startoff += distance;
                irec->br_blockcount -= distance;
        }

        if (end < irec->br_startoff + irec->br_blockcount) {
                distance = irec->br_startoff + irec->br_blockcount - end;
                irec->br_blockcount -= distance;
        }
}

/*
 * Trim the returned map to the required bounds
 */
STATIC void
xfs_bmapi_trim_map(
        struct xfs_bmbt_irec    *mval,
        struct xfs_bmbt_irec    *got,
        xfs_fileoff_t           *bno,
        xfs_filblks_t           len,
        xfs_fileoff_t           obno,
        xfs_fileoff_t           end,
        int                     n,
        uint32_t                flags)
{
        if ((flags & XFS_BMAPI_ENTIRE) ||
            got->br_startoff + got->br_blockcount <= obno) {
                *mval = *got;
                if (isnullstartblock(got->br_startblock))
                        mval->br_startblock = DELAYSTARTBLOCK;
                return;
        }

        if (obno > *bno)
                *bno = obno;
        ASSERT((*bno >= obno) || (n == 0));
        ASSERT(*bno < end);
        mval->br_startoff = *bno;
        if (isnullstartblock(got->br_startblock))
                mval->br_startblock = DELAYSTARTBLOCK;
        else
                mval->br_startblock = got->br_startblock +
                                        (*bno - got->br_startoff);
        /*
         * Return the minimum of what we got and what we asked for for
         * the length.  We can use the len variable here because it is
         * modified below and we could have been there before coming
         * here if the first part of the allocation didn't overlap what
         * was asked for.
         */
        mval->br_blockcount = XFS_FILBLKS_MIN(end - *bno,
                        got->br_blockcount - (*bno - got->br_startoff));
        mval->br_state = got->br_state;
        ASSERT(mval->br_blockcount <= len);
        return;
}

/*
 * Update and validate the extent map to return
 */
STATIC void
xfs_bmapi_update_map(
        struct xfs_bmbt_irec    **map,
        xfs_fileoff_t           *bno,
        xfs_filblks_t           *len,
        xfs_fileoff_t           obno,
        xfs_fileoff_t           end,
        int                     *n,
        uint32_t                flags)
{
        xfs_bmbt_irec_t *mval = *map;

        ASSERT((flags & XFS_BMAPI_ENTIRE) ||
               ((mval->br_startoff + mval->br_blockcount) <= end));
        ASSERT((flags & XFS_BMAPI_ENTIRE) || (mval->br_blockcount <= *len) ||
               (mval->br_startoff < obno));

        *bno = mval->br_startoff + mval->br_blockcount;
        *len = end - *bno;
        if (*n > 0 && mval->br_startoff == mval[-1].br_startoff) {
                /* update previous map with new information */
                ASSERT(mval->br_startblock == mval[-1].br_startblock);
                ASSERT(mval->br_blockcount > mval[-1].br_blockcount);
                ASSERT(mval->br_state == mval[-1].br_state);
                mval[-1].br_blockcount = mval->br_blockcount;
                mval[-1].br_state = mval->br_state;
        } else if (*n > 0 && mval->br_startblock != DELAYSTARTBLOCK &&
                   mval[-1].br_startblock != DELAYSTARTBLOCK &&
                   mval[-1].br_startblock != HOLESTARTBLOCK &&
                   mval->br_startblock == mval[-1].br_startblock +
                                          mval[-1].br_blockcount &&
                   mval[-1].br_state == mval->br_state) {
                ASSERT(mval->br_startoff ==
                       mval[-1].br_startoff + mval[-1].br_blockcount);
                mval[-1].br_blockcount += mval->br_blockcount;
        } else if (*n > 0 &&
                   mval->br_startblock == DELAYSTARTBLOCK &&
                   mval[-1].br_startblock == DELAYSTARTBLOCK &&
                   mval->br_startoff ==
                   mval[-1].br_startoff + mval[-1].br_blockcount) {
                mval[-1].br_blockcount += mval->br_blockcount;
                mval[-1].br_state = mval->br_state;
        } else if (!((*n == 0) &&
                     ((mval->br_startoff + mval->br_blockcount) <=
                      obno))) {
                mval++;
                (*n)++;
        }
        *map = mval;
}

/*
 * Map file blocks to filesystem blocks without allocation.
 */
int
xfs_bmapi_read(
        struct xfs_inode        *ip,
        xfs_fileoff_t           bno,
        xfs_filblks_t           len,
        struct xfs_bmbt_irec    *mval,
        int                     *nmap,
        uint32_t                flags)
{
        struct xfs_mount        *mp = ip->i_mount;
        int                     whichfork = xfs_bmapi_whichfork(flags);
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec    got;
        xfs_fileoff_t           obno;
        xfs_fileoff_t           end;
        struct xfs_iext_cursor  icur;
        int                     error;
        bool                    eof = false;
        int                     n = 0;

        ASSERT(*nmap >= 1);
        ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_ENTIRE)));
        xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);

        if (WARN_ON_ONCE(!ifp)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        XFS_STATS_INC(mp, xs_blk_mapr);

        error = xfs_iread_extents(NULL, ip, whichfork);
        if (error)
                return error;

        if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
                eof = true;
        end = bno + len;
        obno = bno;

        while (bno < end && n < *nmap) {
                /* Reading past eof, act as though there's a hole up to end. */
                if (eof)
                        got.br_startoff = end;
                if (got.br_startoff > bno) {
                        /* Reading in a hole.  */
                        mval->br_startoff = bno;
                        mval->br_startblock = HOLESTARTBLOCK;
                        mval->br_blockcount =
                                XFS_FILBLKS_MIN(len, got.br_startoff - bno);
                        mval->br_state = XFS_EXT_NORM;
                        bno += mval->br_blockcount;
                        len -= mval->br_blockcount;
                        mval++;
                        n++;
                        continue;
                }

                /* set up the extent map to return. */
                xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
                xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);

                /* If we're done, stop now. */
                if (bno >= end || n >= *nmap)
                        break;

                /* Else go on to the next record. */
                if (!xfs_iext_next_extent(ifp, &icur, &got))
                        eof = true;
        }
        *nmap = n;
        return 0;
}

static int
xfs_bmapi_allocate(
        struct xfs_bmalloca     *bma)
{
        struct xfs_mount        *mp = bma->ip->i_mount;
        int                     whichfork = xfs_bmapi_whichfork(bma->flags);
        struct xfs_ifork        *ifp = xfs_ifork_ptr(bma->ip, whichfork);
        int                     error;

        ASSERT(bma->length > 0);
        ASSERT(bma->length <= XFS_MAX_BMBT_EXTLEN);

        if (bma->flags & XFS_BMAPI_CONTIG)
                bma->minlen = bma->length;
        else
                bma->minlen = 1;

        if (!(bma->flags & XFS_BMAPI_METADATA)) {
                /*
                 * For the data and COW fork, the first data in the file is
                 * treated differently to all other allocations. For the
                 * attribute fork, we only need to ensure the allocated range
                 * is not on the busy list.
                 */
                bma->datatype = XFS_ALLOC_NOBUSY;
                if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK) {
                        bma->datatype |= XFS_ALLOC_USERDATA;
                        if (bma->offset == 0)
                                bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;

                        if (mp->m_dalign && bma->length >= mp->m_dalign) {
                                error = xfs_bmap_isaeof(bma, whichfork);
                                if (error)
                                        return error;
                        }
                }
        }

        if ((bma->datatype & XFS_ALLOC_USERDATA) &&
            XFS_IS_REALTIME_INODE(bma->ip))
                error = xfs_bmap_rtalloc(bma);
        else
                error = xfs_bmap_btalloc(bma);
        if (error)
                return error;
        if (bma->blkno == NULLFSBLOCK)
                return -ENOSPC;

        if (WARN_ON_ONCE(!xfs_valid_startblock(bma->ip, bma->blkno))) {
                xfs_bmap_mark_sick(bma->ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (bma->flags & XFS_BMAPI_ZERO) {
                error = xfs_zero_extent(bma->ip, bma->blkno, bma->length);
                if (error)
                        return error;
        }

        if (ifp->if_format == XFS_DINODE_FMT_BTREE && !bma->cur)
                bma->cur = xfs_bmbt_init_cursor(mp, bma->tp, bma->ip, whichfork);
        /*
         * Bump the number of extents we've allocated
         * in this call.
         */
        bma->nallocs++;

        if (bma->cur && bma->wasdel)
                bma->cur->bc_flags |= XFS_BTREE_BMBT_WASDEL;

        bma->got.br_startoff = bma->offset;
        bma->got.br_startblock = bma->blkno;
        bma->got.br_blockcount = bma->length;
        bma->got.br_state = XFS_EXT_NORM;

        if (bma->flags & XFS_BMAPI_PREALLOC)
                bma->got.br_state = XFS_EXT_UNWRITTEN;

        if (bma->wasdel)
                error = xfs_bmap_add_extent_delay_real(bma, whichfork);
        else
                error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
                                whichfork, &bma->icur, &bma->cur, &bma->got,
                                &bma->logflags, bma->flags);
        if (error)
                return error;

        /*
         * Update our extent pointer, given that xfs_bmap_add_extent_delay_real
         * or xfs_bmap_add_extent_hole_real might have merged it into one of
         * the neighbouring ones.
         */
        xfs_iext_get_extent(ifp, &bma->icur, &bma->got);

        ASSERT(bma->got.br_startoff <= bma->offset);
        ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
               bma->offset + bma->length);
        ASSERT(bma->got.br_state == XFS_EXT_NORM ||
               bma->got.br_state == XFS_EXT_UNWRITTEN);
        return 0;
}

STATIC int
xfs_bmapi_convert_unwritten(
        struct xfs_bmalloca     *bma,
        struct xfs_bmbt_irec    *mval,
        xfs_filblks_t           len,
        uint32_t                flags)
{
        int                     whichfork = xfs_bmapi_whichfork(flags);
        struct xfs_ifork        *ifp = xfs_ifork_ptr(bma->ip, whichfork);
        int                     tmp_logflags = 0;
        int                     error;

        /* check if we need to do unwritten->real conversion */
        if (mval->br_state == XFS_EXT_UNWRITTEN &&
            (flags & XFS_BMAPI_PREALLOC))
                return 0;

        /* check if we need to do real->unwritten conversion */
        if (mval->br_state == XFS_EXT_NORM &&
            (flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT)) !=
                        (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT))
                return 0;

        /*
         * Modify (by adding) the state flag, if writing.
         */
        ASSERT(mval->br_blockcount <= len);
        if (ifp->if_format == XFS_DINODE_FMT_BTREE && !bma->cur) {
                bma->cur = xfs_bmbt_init_cursor(bma->ip->i_mount, bma->tp,
                                        bma->ip, whichfork);
        }
        mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
                                ? XFS_EXT_NORM : XFS_EXT_UNWRITTEN;

        /*
         * Before insertion into the bmbt, zero the range being converted
         * if required.
         */
        if (flags & XFS_BMAPI_ZERO) {
                error = xfs_zero_extent(bma->ip, mval->br_startblock,
                                        mval->br_blockcount);
                if (error)
                        return error;
        }

        error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
                        &bma->icur, &bma->cur, mval, &tmp_logflags);
        /*
         * Log the inode core unconditionally in the unwritten extent conversion
         * path because the conversion might not have done so (e.g., if the
         * extent count hasn't changed). We need to make sure the inode is dirty
         * in the transaction for the sake of fsync(), even if nothing has
         * changed, because fsync() will not force the log for this transaction
         * unless it sees the inode pinned.
         *
         * Note: If we're only converting cow fork extents, there aren't
         * any on-disk updates to make, so we don't need to log anything.
         */
        if (whichfork != XFS_COW_FORK)
                bma->logflags |= tmp_logflags | XFS_ILOG_CORE;
        if (error)
                return error;

        /*
         * Update our extent pointer, given that
         * xfs_bmap_add_extent_unwritten_real might have merged it into one
         * of the neighbouring ones.
         */
        xfs_iext_get_extent(ifp, &bma->icur, &bma->got);

        /*
         * We may have combined previously unwritten space with written space,
         * so generate another request.
         */
        if (mval->br_blockcount < len)
                return -EAGAIN;
        return 0;
}

xfs_extlen_t
xfs_bmapi_minleft(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     fork)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, fork);

        if (tp && tp->t_highest_agno != NULLAGNUMBER)
                return 0;
        if (ifp->if_format != XFS_DINODE_FMT_BTREE)
                return 1;
        return be16_to_cpu(ifp->if_broot->bb_level) + 1;
}

/*
 * Log whatever the flags say, even if error.  Otherwise we might miss detecting
 * a case where the data is changed, there's an error, and it's not logged so we
 * don't shutdown when we should.  Don't bother logging extents/btree changes if
 * we converted to the other format.
 */
static void
xfs_bmapi_finish(
        struct xfs_bmalloca     *bma,
        int                     whichfork,
        int                     error)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(bma->ip, whichfork);

        if ((bma->logflags & xfs_ilog_fext(whichfork)) &&
            ifp->if_format != XFS_DINODE_FMT_EXTENTS)
                bma->logflags &= ~xfs_ilog_fext(whichfork);
        else if ((bma->logflags & xfs_ilog_fbroot(whichfork)) &&
                 ifp->if_format != XFS_DINODE_FMT_BTREE)
                bma->logflags &= ~xfs_ilog_fbroot(whichfork);

        if (bma->logflags)
                xfs_trans_log_inode(bma->tp, bma->ip, bma->logflags);
        if (bma->cur)
                xfs_btree_del_cursor(bma->cur, error);
}

/*
 * Map file blocks to filesystem blocks, and allocate blocks or convert the
 * extent state if necessary.  Details behaviour is controlled by the flags
 * parameter.  Only allocates blocks from a single allocation group, to avoid
 * locking problems.
 *
 * Returns 0 on success and places the extent mappings in mval.  nmaps is used
 * as an input/output parameter where the caller specifies the maximum number
 * of mappings that may be returned and xfs_bmapi_write passes back the number
 * of mappings (including existing mappings) it found.
 *
 * Returns a negative error code on failure, including -ENOSPC when it could not
 * allocate any blocks and -ENOSR when it did allocate blocks to convert a
 * delalloc range, but those blocks were before the passed in range.
 */
int
xfs_bmapi_write(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode */
        xfs_fileoff_t           bno,            /* starting file offs. mapped */
        xfs_filblks_t           len,            /* length to map in file */
        uint32_t                flags,          /* XFS_BMAPI_... */
        xfs_extlen_t            total,          /* total blocks needed */
        struct xfs_bmbt_irec    *mval,          /* output: map values */
        int                     *nmap)          /* i/o: mval size/count */
{
        struct xfs_bmalloca     bma = {
                .tp             = tp,
                .ip             = ip,
                .total          = total,
        };
        struct xfs_mount        *mp = ip->i_mount;
        int                     whichfork = xfs_bmapi_whichfork(flags);
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        xfs_fileoff_t           end;            /* end of mapped file region */
        bool                    eof = false;    /* after the end of extents */
        int                     error;          /* error return */
        int                     n;              /* current extent index */
        xfs_fileoff_t           obno;           /* old block number (offset) */

#ifdef DEBUG
        xfs_fileoff_t           orig_bno;       /* original block number value */
        int                     orig_flags;     /* original flags arg value */
        xfs_filblks_t           orig_len;       /* original value of len arg */
        struct xfs_bmbt_irec    *orig_mval;     /* original value of mval */
        int                     orig_nmap;      /* original value of *nmap */

        orig_bno = bno;
        orig_len = len;
        orig_flags = flags;
        orig_mval = mval;
        orig_nmap = *nmap;
#endif

        ASSERT(*nmap >= 1);
        ASSERT(*nmap <= XFS_BMAP_MAX_NMAP);
        ASSERT(tp != NULL);
        ASSERT(len > 0);
        ASSERT(ifp->if_format != XFS_DINODE_FMT_LOCAL);
        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        ASSERT(!(flags & XFS_BMAPI_REMAP));

        /* zeroing is for currently only for data extents, not metadata */
        ASSERT((flags & (XFS_BMAPI_METADATA | XFS_BMAPI_ZERO)) !=
                        (XFS_BMAPI_METADATA | XFS_BMAPI_ZERO));
        /*
         * we can allocate unwritten extents or pre-zero allocated blocks,
         * but it makes no sense to do both at once. This would result in
         * zeroing the unwritten extent twice, but it still being an
         * unwritten extent....
         */
        ASSERT((flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO)) !=
                        (XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO));

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        XFS_STATS_INC(mp, xs_blk_mapw);

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                goto error0;

        if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
                eof = true;
        if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
                bma.prev.br_startoff = NULLFILEOFF;
        bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);

        n = 0;
        end = bno + len;
        obno = bno;
        while (bno < end && n < *nmap) {
                bool                    need_alloc = false, wasdelay = false;

                /* in hole or beyond EOF? */
                if (eof || bma.got.br_startoff > bno) {
                        /*
                         * CoW fork conversions should /never/ hit EOF or
                         * holes.  There should always be something for us
                         * to work on.
                         */
                        ASSERT(!((flags & XFS_BMAPI_CONVERT) &&
                                 (flags & XFS_BMAPI_COWFORK)));

                        need_alloc = true;
                } else if (isnullstartblock(bma.got.br_startblock)) {
                        wasdelay = true;
                }

                /*
                 * First, deal with the hole before the allocated space
                 * that we found, if any.
                 */
                if (need_alloc || wasdelay) {
                        bma.eof = eof;
                        bma.conv = !!(flags & XFS_BMAPI_CONVERT);
                        bma.wasdel = wasdelay;
                        bma.offset = bno;
                        bma.flags = flags;

                        /*
                         * There's a 32/64 bit type mismatch between the
                         * allocation length request (which can be 64 bits in
                         * length) and the bma length request, which is
                         * xfs_extlen_t and therefore 32 bits. Hence we have to
                         * be careful and do the min() using the larger type to
                         * avoid overflows.
                         */
                        bma.length = XFS_FILBLKS_MIN(len, XFS_MAX_BMBT_EXTLEN);

                        if (wasdelay) {
                                bma.length = XFS_FILBLKS_MIN(bma.length,
                                        bma.got.br_blockcount -
                                        (bno - bma.got.br_startoff));
                        } else {
                                if (!eof)
                                        bma.length = XFS_FILBLKS_MIN(bma.length,
                                                bma.got.br_startoff - bno);
                        }

                        ASSERT(bma.length > 0);
                        error = xfs_bmapi_allocate(&bma);
                        if (error) {
                                /*
                                 * If we already allocated space in a previous
                                 * iteration return what we go so far when
                                 * running out of space.
                                 */
                                if (error == -ENOSPC && bma.nallocs)
                                        break;
                                goto error0;
                        }

                        /*
                         * If this is a CoW allocation, record the data in
                         * the refcount btree for orphan recovery.
                         */
                        if (whichfork == XFS_COW_FORK)
                                xfs_refcount_alloc_cow_extent(tp,
                                                XFS_IS_REALTIME_INODE(ip),
                                                bma.blkno, bma.length);
                }

                /* Deal with the allocated space we found.  */
                xfs_bmapi_trim_map(mval, &bma.got, &bno, len, obno,
                                                        end, n, flags);

                /* Execute unwritten extent conversion if necessary */
                error = xfs_bmapi_convert_unwritten(&bma, mval, len, flags);
                if (error == -EAGAIN)
                        continue;
                if (error)
                        goto error0;

                /* update the extent map to return */
                xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);

                /*
                 * If we're done, stop now.  Stop when we've allocated
                 * XFS_BMAP_MAX_NMAP extents no matter what.  Otherwise
                 * the transaction may get too big.
                 */
                if (bno >= end || n >= *nmap || bma.nallocs >= *nmap)
                        break;

                /* Else go on to the next record. */
                bma.prev = bma.got;
                if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
                        eof = true;
        }

        error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
                        whichfork);
        if (error)
                goto error0;

        ASSERT(ifp->if_format != XFS_DINODE_FMT_BTREE ||
               ifp->if_nextents > XFS_IFORK_MAXEXT(ip, whichfork));
        xfs_bmapi_finish(&bma, whichfork, 0);
        xfs_bmap_validate_ret(orig_bno, orig_len, orig_flags, orig_mval,
                orig_nmap, n);

        /*
         * When converting delayed allocations, xfs_bmapi_allocate ignores
         * the passed in bno and always converts from the start of the found
         * delalloc extent.
         *
         * To avoid a successful return with *nmap set to 0, return the magic
         * -ENOSR error code for this particular case so that the caller can
         * handle it.
         */
        if (!n) {
                ASSERT(bma.nallocs >= *nmap);
                return -ENOSR;
        }
        *nmap = n;
        return 0;
error0:
        xfs_bmapi_finish(&bma, whichfork, error);
        return error;
}

/*
 * Convert an existing delalloc extent to real blocks based on file offset. This
 * attempts to allocate the entire delalloc extent and may require multiple
 * invocations to allocate the target offset if a large enough physical extent
 * is not available.
 */
static int
xfs_bmapi_convert_one_delalloc(
        struct xfs_inode        *ip,
        int                     whichfork,
        xfs_off_t               offset,
        struct iomap            *iomap,
        unsigned int            *seq)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_mount        *mp = ip->i_mount;
        xfs_fileoff_t           offset_fsb = XFS_B_TO_FSBT(mp, offset);
        struct xfs_bmalloca     bma = { NULL };
        uint16_t                flags = 0;
        struct xfs_trans        *tp;
        int                     error;

        if (whichfork == XFS_COW_FORK)
                flags |= IOMAP_F_SHARED;

        /*
         * Space for the extent and indirect blocks was reserved when the
         * delalloc extent was created so there's no need to do so here.
         */
        error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
                                XFS_TRANS_RESERVE, &tp);
        if (error)
                return error;

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);

        error = xfs_iext_count_extend(tp, ip, whichfork,
                        XFS_IEXT_ADD_NOSPLIT_CNT);
        if (error)
                goto out_trans_cancel;

        if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
            bma.got.br_startoff > offset_fsb) {
                /*
                 * No extent found in the range we are trying to convert.  This
                 * should only happen for the COW fork, where another thread
                 * might have moved the extent to the data fork in the meantime.
                 */
                WARN_ON_ONCE(whichfork != XFS_COW_FORK);
                error = -EAGAIN;
                goto out_trans_cancel;
        }

        /*
         * If we find a real extent here we raced with another thread converting
         * the extent.  Just return the real extent at this offset.
         */
        if (!isnullstartblock(bma.got.br_startblock)) {
                xfs_bmbt_to_iomap(ip, iomap, &bma.got, 0, flags,
                                xfs_iomap_inode_sequence(ip, flags));
                if (seq)
                        *seq = READ_ONCE(ifp->if_seq);
                goto out_trans_cancel;
        }

        bma.tp = tp;
        bma.ip = ip;
        bma.wasdel = true;
        bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);

        /*
         * Always allocate convert from the start of the delalloc extent even if
         * that is outside the passed in range to create large contiguous
         * extents on disk.
         */
        bma.offset = bma.got.br_startoff;
        bma.length = bma.got.br_blockcount;

        /*
         * When we're converting the delalloc reservations backing dirty pages
         * in the page cache, we must be careful about how we create the new
         * extents:
         *
         * New CoW fork extents are created unwritten, turned into real extents
         * when we're about to write the data to disk, and mapped into the data
         * fork after the write finishes.  End of story.
         *
         * New data fork extents must be mapped in as unwritten and converted
         * to real extents after the write succeeds to avoid exposing stale
         * disk contents if we crash.
         */
        bma.flags = XFS_BMAPI_PREALLOC;
        if (whichfork == XFS_COW_FORK)
                bma.flags |= XFS_BMAPI_COWFORK;

        if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
                bma.prev.br_startoff = NULLFILEOFF;

        error = xfs_bmapi_allocate(&bma);
        if (error)
                goto out_finish;

        XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, bma.length));
        XFS_STATS_INC(mp, xs_xstrat_quick);

        ASSERT(!isnullstartblock(bma.got.br_startblock));
        xfs_bmbt_to_iomap(ip, iomap, &bma.got, 0, flags,
                                xfs_iomap_inode_sequence(ip, flags));
        if (seq)
                *seq = READ_ONCE(ifp->if_seq);

        if (whichfork == XFS_COW_FORK)
                xfs_refcount_alloc_cow_extent(tp, XFS_IS_REALTIME_INODE(ip),
                                bma.blkno, bma.length);

        error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
                        whichfork);
        if (error)
                goto out_finish;

        xfs_bmapi_finish(&bma, whichfork, 0);
        error = xfs_trans_commit(tp);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;

out_finish:
        xfs_bmapi_finish(&bma, whichfork, error);
out_trans_cancel:
        xfs_trans_cancel(tp);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
}

/*
 * Pass in a dellalloc extent and convert it to real extents, return the real
 * extent that maps offset_fsb in iomap.
 */
int
xfs_bmapi_convert_delalloc(
        struct xfs_inode        *ip,
        int                     whichfork,
        loff_t                  offset,
        struct iomap            *iomap,
        unsigned int            *seq)
{
        int                     error;

        /*
         * Attempt to allocate whatever delalloc extent currently backs offset
         * and put the result into iomap.  Allocate in a loop because it may
         * take several attempts to allocate real blocks for a contiguous
         * delalloc extent if free space is sufficiently fragmented.
         */
        do {
                error = xfs_bmapi_convert_one_delalloc(ip, whichfork, offset,
                                        iomap, seq);
                if (error)
                        return error;
        } while (iomap->offset + iomap->length <= offset);

        return 0;
}

int
xfs_bmapi_remap(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           bno,
        xfs_filblks_t           len,
        xfs_fsblock_t           startblock,
        uint32_t                flags)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp;
        struct xfs_btree_cur    *cur = NULL;
        struct xfs_bmbt_irec    got;
        struct xfs_iext_cursor  icur;
        int                     whichfork = xfs_bmapi_whichfork(flags);
        int                     logflags = 0, error;

        ifp = xfs_ifork_ptr(ip, whichfork);
        ASSERT(len > 0);
        ASSERT(len <= (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN);
        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC |
                           XFS_BMAPI_NORMAP)));
        ASSERT((flags & (XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC)) !=
                        (XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC));

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
                /* make sure we only reflink into a hole. */
                ASSERT(got.br_startoff > bno);
                ASSERT(got.br_startoff - bno >= len);
        }

        ip->i_nblocks += len;
        ip->i_delayed_blks -= len; /* see xfs_bmap_defer_add */
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        if (ifp->if_format == XFS_DINODE_FMT_BTREE)
                cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);

        got.br_startoff = bno;
        got.br_startblock = startblock;
        got.br_blockcount = len;
        if (flags & XFS_BMAPI_PREALLOC)
                got.br_state = XFS_EXT_UNWRITTEN;
        else
                got.br_state = XFS_EXT_NORM;

        error = xfs_bmap_add_extent_hole_real(tp, ip, whichfork, &icur,
                        &cur, &got, &logflags, flags);
        if (error)
                goto error0;

        error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags, whichfork);

error0:
        if (ip->i_df.if_format != XFS_DINODE_FMT_EXTENTS)
                logflags &= ~XFS_ILOG_DEXT;
        else if (ip->i_df.if_format != XFS_DINODE_FMT_BTREE)
                logflags &= ~XFS_ILOG_DBROOT;

        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        if (cur)
                xfs_btree_del_cursor(cur, error);
        return error;
}

/*
 * When a delalloc extent is split (e.g., due to a hole punch), the original
 * indlen reservation must be shared across the two new extents that are left
 * behind.
 *
 * Given the original reservation and the worst case indlen for the two new
 * extents (as calculated by xfs_bmap_worst_indlen()), split the original
 * reservation fairly across the two new extents. If necessary, steal available
 * blocks from a deleted extent to make up a reservation deficiency (e.g., if
 * ores == 1). The number of stolen blocks is returned. The availability and
 * subsequent accounting of stolen blocks is the responsibility of the caller.
 */
static void
xfs_bmap_split_indlen(
        xfs_filblks_t                   ores,           /* original res. */
        xfs_filblks_t                   *indlen1,       /* ext1 worst indlen */
        xfs_filblks_t                   *indlen2)       /* ext2 worst indlen */
{
        xfs_filblks_t                   len1 = *indlen1;
        xfs_filblks_t                   len2 = *indlen2;
        xfs_filblks_t                   nres = len1 + len2; /* new total res. */
        xfs_filblks_t                   resfactor;

        /*
         * We can't meet the total required reservation for the two extents.
         * Calculate the percent of the overall shortage between both extents
         * and apply this percentage to each of the requested indlen values.
         * This distributes the shortage fairly and reduces the chances that one
         * of the two extents is left with nothing when extents are repeatedly
         * split.
         */
        resfactor = (ores * 100);
        do_div(resfactor, nres);
        len1 *= resfactor;
        do_div(len1, 100);
        len2 *= resfactor;
        do_div(len2, 100);
        ASSERT(len1 + len2 <= ores);
        ASSERT(len1 < *indlen1 && len2 < *indlen2);

        /*
         * Hand out the remainder to each extent. If one of the two reservations
         * is zero, we want to make sure that one gets a block first. The loop
         * below starts with len1, so hand len2 a block right off the bat if it
         * is zero.
         */
        ores -= (len1 + len2);
        ASSERT((*indlen1 - len1) + (*indlen2 - len2) >= ores);
        if (ores && !len2 && *indlen2) {
                len2++;
                ores--;
        }
        while (ores) {
                if (len1 < *indlen1) {
                        len1++;
                        ores--;
                }
                if (!ores)
                        break;
                if (len2 < *indlen2) {
                        len2++;
                        ores--;
                }
        }

        *indlen1 = len1;
        *indlen2 = len2;
}

void
xfs_bmap_del_extent_delay(
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_iext_cursor  *icur,
        struct xfs_bmbt_irec    *got,
        struct xfs_bmbt_irec    *del,
        uint32_t                bflags) /* bmapi flags */
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec    new;
        int64_t                 da_old, da_new, da_diff = 0;
        xfs_fileoff_t           del_endoff, got_endoff;
        xfs_filblks_t           got_indlen, new_indlen, stolen = 0;
        uint32_t                state = xfs_bmap_fork_to_state(whichfork);
        uint64_t                fdblocks;
        bool                    isrt;

        XFS_STATS_INC(mp, xs_del_exlist);

        isrt = xfs_ifork_is_realtime(ip, whichfork);
        del_endoff = del->br_startoff + del->br_blockcount;
        got_endoff = got->br_startoff + got->br_blockcount;
        da_old = startblockval(got->br_startblock);
        da_new = 0;

        ASSERT(del->br_blockcount > 0);
        ASSERT(got->br_startoff <= del->br_startoff);
        ASSERT(got_endoff >= del_endoff);

        /*
         * Update the inode delalloc counter now and wait to update the
         * sb counters as we might have to borrow some blocks for the
         * indirect block accounting.
         */
        xfs_quota_unreserve_blkres(ip, del->br_blockcount);
        ip->i_delayed_blks -= del->br_blockcount;

        if (got->br_startoff == del->br_startoff)
                state |= BMAP_LEFT_FILLING;
        if (got_endoff == del_endoff)
                state |= BMAP_RIGHT_FILLING;

        switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
                /*
                 * Matches the whole extent.  Delete the entry.
                 */
                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                break;
        case BMAP_LEFT_FILLING:
                /*
                 * Deleting the first part of the extent.
                 */
                got->br_startoff = del_endoff;
                got->br_blockcount -= del->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
                                got->br_blockcount), da_old);
                got->br_startblock = nullstartblock((int)da_new);
                xfs_iext_update_extent(ip, state, icur, got);
                break;
        case BMAP_RIGHT_FILLING:
                /*
                 * Deleting the last part of the extent.
                 */
                got->br_blockcount = got->br_blockcount - del->br_blockcount;
                da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
                                got->br_blockcount), da_old);
                got->br_startblock = nullstartblock((int)da_new);
                xfs_iext_update_extent(ip, state, icur, got);
                break;
        case 0:
                /*
                 * Deleting the middle of the extent.
                 *
                 * Distribute the original indlen reservation across the two new
                 * extents.  Steal blocks from the deleted extent if necessary.
                 * Stealing blocks simply fudges the fdblocks accounting below.
                 * Warn if either of the new indlen reservations is zero as this
                 * can lead to delalloc problems.
                 */
                got->br_blockcount = del->br_startoff - got->br_startoff;
                got_indlen = xfs_bmap_worst_indlen(ip, got->br_blockcount);

                new.br_blockcount = got_endoff - del_endoff;
                new_indlen = xfs_bmap_worst_indlen(ip, new.br_blockcount);

                WARN_ON_ONCE(!got_indlen || !new_indlen);
                /*
                 * Steal as many blocks as we can to try and satisfy the worst
                 * case indlen for both new extents.
                 *
                 * However, we can't just steal reservations from the data
                 * blocks if this is an RT inodes as the data and metadata
                 * blocks come from different pools.  We'll have to live with
                 * under-filled indirect reservation in this case.
                 */
                da_new = got_indlen + new_indlen;
                if (da_new > da_old && !isrt) {
                        stolen = XFS_FILBLKS_MIN(da_new - da_old,
                                                 del->br_blockcount);
                        da_old += stolen;
                }
                if (da_new > da_old)
                        xfs_bmap_split_indlen(da_old, &got_indlen, &new_indlen);
                da_new = got_indlen + new_indlen;

                got->br_startblock = nullstartblock((int)got_indlen);

                new.br_startoff = del_endoff;
                new.br_state = got->br_state;
                new.br_startblock = nullstartblock((int)new_indlen);

                xfs_iext_update_extent(ip, state, icur, got);
                xfs_iext_next(ifp, icur);
                xfs_iext_insert(ip, icur, &new, state);

                del->br_blockcount -= stolen;
                break;
        }

        ASSERT(da_old >= da_new);
        da_diff = da_old - da_new;
        fdblocks = da_diff;

        if (bflags & XFS_BMAPI_REMAP) {
                ;
        } else if (isrt) {
                xfs_rtbxlen_t   rtxlen;

                rtxlen = xfs_blen_to_rtbxlen(mp, del->br_blockcount);
                if (xfs_is_zoned_inode(ip))
                        xfs_zoned_add_available(mp, rtxlen);
                xfs_add_frextents(mp, rtxlen);
        } else {
                fdblocks += del->br_blockcount;
        }

        xfs_add_fdblocks(mp, fdblocks);
        xfs_mod_delalloc(ip, -(int64_t)del->br_blockcount, -da_diff);
}

void
xfs_bmap_del_extent_cow(
        struct xfs_inode        *ip,
        struct xfs_iext_cursor  *icur,
        struct xfs_bmbt_irec    *got,
        struct xfs_bmbt_irec    *del)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
        struct xfs_bmbt_irec    new;
        xfs_fileoff_t           del_endoff, got_endoff;
        uint32_t                state = BMAP_COWFORK;

        XFS_STATS_INC(mp, xs_del_exlist);

        del_endoff = del->br_startoff + del->br_blockcount;
        got_endoff = got->br_startoff + got->br_blockcount;

        ASSERT(del->br_blockcount > 0);
        ASSERT(got->br_startoff <= del->br_startoff);
        ASSERT(got_endoff >= del_endoff);
        ASSERT(!isnullstartblock(got->br_startblock));

        if (got->br_startoff == del->br_startoff)
                state |= BMAP_LEFT_FILLING;
        if (got_endoff == del_endoff)
                state |= BMAP_RIGHT_FILLING;

        switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
                /*
                 * Matches the whole extent.  Delete the entry.
                 */
                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                break;
        case BMAP_LEFT_FILLING:
                /*
                 * Deleting the first part of the extent.
                 */
                got->br_startoff = del_endoff;
                got->br_blockcount -= del->br_blockcount;
                got->br_startblock = del->br_startblock + del->br_blockcount;
                xfs_iext_update_extent(ip, state, icur, got);
                break;
        case BMAP_RIGHT_FILLING:
                /*
                 * Deleting the last part of the extent.
                 */
                got->br_blockcount -= del->br_blockcount;
                xfs_iext_update_extent(ip, state, icur, got);
                break;
        case 0:
                /*
                 * Deleting the middle of the extent.
                 */
                got->br_blockcount = del->br_startoff - got->br_startoff;

                new.br_startoff = del_endoff;
                new.br_blockcount = got_endoff - del_endoff;
                new.br_state = got->br_state;
                new.br_startblock = del->br_startblock + del->br_blockcount;

                xfs_iext_update_extent(ip, state, icur, got);
                xfs_iext_next(ifp, icur);
                xfs_iext_insert(ip, icur, &new, state);
                break;
        }
        ip->i_delayed_blks -= del->br_blockcount;
}

static int
xfs_bmap_free_rtblocks(
        struct xfs_trans        *tp,
        struct xfs_bmbt_irec    *del)
{
        struct xfs_rtgroup      *rtg;
        int                     error;

        rtg = xfs_rtgroup_grab(tp->t_mountp, 0);
        if (!rtg)
                return -EIO;

        /*
         * Ensure the bitmap and summary inodes are locked and joined to the
         * transaction before modifying them.
         */
        if (!(tp->t_flags & XFS_TRANS_RTBITMAP_LOCKED)) {
                tp->t_flags |= XFS_TRANS_RTBITMAP_LOCKED;
                xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP);
                xfs_rtgroup_trans_join(tp, rtg, XFS_RTGLOCK_BITMAP);
        }

        error = xfs_rtfree_blocks(tp, rtg, del->br_startblock,
                        del->br_blockcount);
        xfs_rtgroup_rele(rtg);
        return error;
}

/*
 * Called by xfs_bmapi to update file extent records and the btree
 * after removing space.
 */
STATIC int                              /* error */
xfs_bmap_del_extent_real(
        xfs_inode_t             *ip,    /* incore inode pointer */
        xfs_trans_t             *tp,    /* current transaction pointer */
        struct xfs_iext_cursor  *icur,
        struct xfs_btree_cur    *cur,   /* if null, not a btree */
        xfs_bmbt_irec_t         *del,   /* data to remove from extents */
        int                     *logflagsp, /* inode logging flags */
        int                     whichfork, /* data or attr fork */
        uint32_t                bflags) /* bmapi flags */
{
        xfs_fsblock_t           del_endblock=0; /* first block past del */
        xfs_fileoff_t           del_endoff;     /* first offset past del */
        int                     error = 0;      /* error return value */
        struct xfs_bmbt_irec    got;    /* current extent entry */
        xfs_fileoff_t           got_endoff;     /* first offset past got */
        int                     i;      /* temp state */
        struct xfs_ifork        *ifp;   /* inode fork pointer */
        xfs_mount_t             *mp;    /* mount structure */
        xfs_filblks_t           nblks;  /* quota/sb block count */
        xfs_bmbt_irec_t         new;    /* new record to be inserted */
        /* REFERENCED */
        uint                    qfield; /* quota field to update */
        uint32_t                state = xfs_bmap_fork_to_state(whichfork);
        struct xfs_bmbt_irec    old;

        *logflagsp = 0;

        mp = ip->i_mount;
        XFS_STATS_INC(mp, xs_del_exlist);

        ifp = xfs_ifork_ptr(ip, whichfork);
        ASSERT(del->br_blockcount > 0);
        xfs_iext_get_extent(ifp, icur, &got);
        ASSERT(got.br_startoff <= del->br_startoff);
        del_endoff = del->br_startoff + del->br_blockcount;
        got_endoff = got.br_startoff + got.br_blockcount;
        ASSERT(got_endoff >= del_endoff);
        ASSERT(!isnullstartblock(got.br_startblock));
        qfield = 0;

        /*
         * If it's the case where the directory code is running with no block
         * reservation, and the deleted block is in the middle of its extent,
         * and the resulting insert of an extent would cause transformation to
         * btree format, then reject it.  The calling code will then swap blocks
         * around instead.  We have to do this now, rather than waiting for the
         * conversion to btree format, since the transaction will be dirty then.
         */
        if (tp->t_blk_res == 0 &&
            ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
            ifp->if_nextents >= XFS_IFORK_MAXEXT(ip, whichfork) &&
            del->br_startoff > got.br_startoff && del_endoff < got_endoff)
                return -ENOSPC;

        *logflagsp = XFS_ILOG_CORE;
        if (xfs_ifork_is_realtime(ip, whichfork))
                qfield = XFS_TRANS_DQ_RTBCOUNT;
        else
                qfield = XFS_TRANS_DQ_BCOUNT;
        nblks = del->br_blockcount;

        del_endblock = del->br_startblock + del->br_blockcount;
        if (cur) {
                error = xfs_bmbt_lookup_eq(cur, &got, &i);
                if (error)
                        return error;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        return -EFSCORRUPTED;
                }
        }

        if (got.br_startoff == del->br_startoff)
                state |= BMAP_LEFT_FILLING;
        if (got_endoff == del_endoff)
                state |= BMAP_RIGHT_FILLING;

        switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
        case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
                /*
                 * Matches the whole extent.  Delete the entry.
                 */
                xfs_iext_remove(ip, icur, state);
                xfs_iext_prev(ifp, icur);
                ifp->if_nextents--;

                *logflagsp |= XFS_ILOG_CORE;
                if (!cur) {
                        *logflagsp |= xfs_ilog_fext(whichfork);
                        break;
                }
                if ((error = xfs_btree_delete(cur, &i)))
                        return error;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        return -EFSCORRUPTED;
                }
                break;
        case BMAP_LEFT_FILLING:
                /*
                 * Deleting the first part of the extent.
                 */
                got.br_startoff = del_endoff;
                got.br_startblock = del_endblock;
                got.br_blockcount -= del->br_blockcount;
                xfs_iext_update_extent(ip, state, icur, &got);
                if (!cur) {
                        *logflagsp |= xfs_ilog_fext(whichfork);
                        break;
                }
                error = xfs_bmbt_update(cur, &got);
                if (error)
                        return error;
                break;
        case BMAP_RIGHT_FILLING:
                /*
                 * Deleting the last part of the extent.
                 */
                got.br_blockcount -= del->br_blockcount;
                xfs_iext_update_extent(ip, state, icur, &got);
                if (!cur) {
                        *logflagsp |= xfs_ilog_fext(whichfork);
                        break;
                }
                error = xfs_bmbt_update(cur, &got);
                if (error)
                        return error;
                break;
        case 0:
                /*
                 * Deleting the middle of the extent.
                 */

                old = got;

                got.br_blockcount = del->br_startoff - got.br_startoff;
                xfs_iext_update_extent(ip, state, icur, &got);

                new.br_startoff = del_endoff;
                new.br_blockcount = got_endoff - del_endoff;
                new.br_state = got.br_state;
                new.br_startblock = del_endblock;

                *logflagsp |= XFS_ILOG_CORE;
                if (cur) {
                        error = xfs_bmbt_update(cur, &got);
                        if (error)
                                return error;
                        error = xfs_btree_increment(cur, 0, &i);
                        if (error)
                                return error;
                        cur->bc_rec.b = new;
                        error = xfs_btree_insert(cur, &i);
                        if (error && error != -ENOSPC)
                                return error;
                        /*
                         * If get no-space back from btree insert, it tried a
                         * split, and we have a zero block reservation.  Fix up
                         * our state and return the error.
                         */
                        if (error == -ENOSPC) {
                                /*
                                 * Reset the cursor, don't trust it after any
                                 * insert operation.
                                 */
                                error = xfs_bmbt_lookup_eq(cur, &got, &i);
                                if (error)
                                        return error;
                                if (XFS_IS_CORRUPT(mp, i != 1)) {
                                        xfs_btree_mark_sick(cur);
                                        return -EFSCORRUPTED;
                                }
                                /*
                                 * Update the btree record back
                                 * to the original value.
                                 */
                                error = xfs_bmbt_update(cur, &old);
                                if (error)
                                        return error;
                                /*
                                 * Reset the extent record back
                                 * to the original value.
                                 */
                                xfs_iext_update_extent(ip, state, icur, &old);
                                *logflagsp = 0;
                                return -ENOSPC;
                        }
                        if (XFS_IS_CORRUPT(mp, i != 1)) {
                                xfs_btree_mark_sick(cur);
                                return -EFSCORRUPTED;
                        }
                } else
                        *logflagsp |= xfs_ilog_fext(whichfork);

                ifp->if_nextents++;
                xfs_iext_next(ifp, icur);
                xfs_iext_insert(ip, icur, &new, state);
                break;
        }

        /* remove reverse mapping */
        xfs_rmap_unmap_extent(tp, ip, whichfork, del);

        /*
         * If we need to, add to list of extents to delete.
         */
        if (!(bflags & XFS_BMAPI_REMAP)) {
                bool    isrt = xfs_ifork_is_realtime(ip, whichfork);

                if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
                        xfs_refcount_decrease_extent(tp, isrt, del);
                } else if (isrt && !xfs_has_rtgroups(mp)) {
                        error = xfs_bmap_free_rtblocks(tp, del);
                } else {
                        unsigned int    efi_flags = 0;

                        if ((bflags & XFS_BMAPI_NODISCARD) ||
                            del->br_state == XFS_EXT_UNWRITTEN)
                                efi_flags |= XFS_FREE_EXTENT_SKIP_DISCARD;

                        /*
                         * Historically, we did not use EFIs to free realtime
                         * extents.  However, when reverse mapping is enabled,
                         * we must maintain the same order of operations as the
                         * data device, which is: Remove the file mapping,
                         * remove the reverse mapping, and then free the
                         * blocks.  Reflink for realtime volumes requires the
                         * same sort of ordering.  Both features rely on
                         * rtgroups, so let's gate rt EFI usage on rtgroups.
                         */
                        if (isrt)
                                efi_flags |= XFS_FREE_EXTENT_REALTIME;

                        error = xfs_free_extent_later(tp, del->br_startblock,
                                        del->br_blockcount, NULL,
                                        XFS_AG_RESV_NONE, efi_flags);
                }
                if (error)
                        return error;
        }

        /*
         * Adjust inode # blocks in the file.
         */
        if (nblks)
                ip->i_nblocks -= nblks;
        /*
         * Adjust quota data.
         */
        if (qfield && !(bflags & XFS_BMAPI_REMAP))
                xfs_trans_mod_dquot_byino(tp, ip, qfield, (long)-nblks);

        return 0;
}

/*
 * Unmap (remove) blocks from a file.
 * If nexts is nonzero then the number of extents to remove is limited to
 * that value.  If not all extents in the block range can be removed then
 * *done is set.
 */
static int
__xfs_bunmapi(
        struct xfs_trans        *tp,            /* transaction pointer */
        struct xfs_inode        *ip,            /* incore inode */
        xfs_fileoff_t           start,          /* first file offset deleted */
        xfs_filblks_t           *rlen,          /* i/o: amount remaining */
        uint32_t                flags,          /* misc flags */
        xfs_extnum_t            nexts)          /* number of extents max */
{
        struct xfs_btree_cur    *cur;           /* bmap btree cursor */
        struct xfs_bmbt_irec    del;            /* extent being deleted */
        int                     error;          /* error return value */
        xfs_extnum_t            extno;          /* extent number in list */
        struct xfs_bmbt_irec    got;            /* current extent record */
        struct xfs_ifork        *ifp;           /* inode fork pointer */
        int                     isrt;           /* freeing in rt area */
        int                     logflags;       /* transaction logging flags */
        xfs_extlen_t            mod;            /* rt extent offset */
        struct xfs_mount        *mp = ip->i_mount;
        int                     tmp_logflags;   /* partial logging flags */
        int                     wasdel;         /* was a delayed alloc extent */
        int                     whichfork;      /* data or attribute fork */
        xfs_filblks_t           len = *rlen;    /* length to unmap in file */
        xfs_fileoff_t           end;
        struct xfs_iext_cursor  icur;
        bool                    done = false;

        trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);

        whichfork = xfs_bmapi_whichfork(flags);
        ASSERT(whichfork != XFS_COW_FORK);
        ifp = xfs_ifork_ptr(ip, whichfork);
        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp))) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }
        if (xfs_is_shutdown(mp))
                return -EIO;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        ASSERT(len > 0);
        ASSERT(nexts >= 0);

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        if (xfs_iext_count(ifp) == 0) {
                *rlen = 0;
                return 0;
        }
        XFS_STATS_INC(mp, xs_blk_unmap);
        isrt = xfs_ifork_is_realtime(ip, whichfork);
        end = start + len;

        if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
                *rlen = 0;
                return 0;
        }
        end--;

        logflags = 0;
        if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
                ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE);
                cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
        } else
                cur = NULL;

        extno = 0;
        while (end != (xfs_fileoff_t)-1 && end >= start &&
               (nexts == 0 || extno < nexts)) {
                /*
                 * Is the found extent after a hole in which end lives?
                 * Just back up to the previous extent, if so.
                 */
                if (got.br_startoff > end &&
                    !xfs_iext_prev_extent(ifp, &icur, &got)) {
                        done = true;
                        break;
                }
                /*
                 * Is the last block of this extent before the range
                 * we're supposed to delete?  If so, we're done.
                 */
                end = XFS_FILEOFF_MIN(end,
                        got.br_startoff + got.br_blockcount - 1);
                if (end < start)
                        break;
                /*
                 * Then deal with the (possibly delayed) allocated space
                 * we found.
                 */
                del = got;
                wasdel = isnullstartblock(del.br_startblock);

                if (got.br_startoff < start) {
                        del.br_startoff = start;
                        del.br_blockcount -= start - got.br_startoff;
                        if (!wasdel)
                                del.br_startblock += start - got.br_startoff;
                }
                if (del.br_startoff + del.br_blockcount > end + 1)
                        del.br_blockcount = end + 1 - del.br_startoff;

                if (!isrt || (flags & XFS_BMAPI_REMAP))
                        goto delete;

                mod = xfs_rtb_to_rtxoff(mp,
                                del.br_startblock + del.br_blockcount);
                if (mod) {
                        /*
                         * Realtime extent not lined up at the end.
                         * The extent could have been split into written
                         * and unwritten pieces, or we could just be
                         * unmapping part of it.  But we can't really
                         * get rid of part of a realtime extent.
                         */
                        if (del.br_state == XFS_EXT_UNWRITTEN) {
                                /*
                                 * This piece is unwritten, or we're not
                                 * using unwritten extents.  Skip over it.
                                 */
                                ASSERT((flags & XFS_BMAPI_REMAP) || end >= mod);
                                end -= mod > del.br_blockcount ?
                                        del.br_blockcount : mod;
                                if (end < got.br_startoff &&
                                    !xfs_iext_prev_extent(ifp, &icur, &got)) {
                                        done = true;
                                        break;
                                }
                                continue;
                        }
                        /*
                         * It's written, turn it unwritten.
                         * This is better than zeroing it.
                         */
                        ASSERT(del.br_state == XFS_EXT_NORM);
                        ASSERT(tp->t_blk_res > 0);
                        /*
                         * If this spans a realtime extent boundary,
                         * chop it back to the start of the one we end at.
                         */
                        if (del.br_blockcount > mod) {
                                del.br_startoff += del.br_blockcount - mod;
                                del.br_startblock += del.br_blockcount - mod;
                                del.br_blockcount = mod;
                        }
                        del.br_state = XFS_EXT_UNWRITTEN;
                        error = xfs_bmap_add_extent_unwritten_real(tp, ip,
                                        whichfork, &icur, &cur, &del,
                                        &logflags);
                        if (error)
                                goto error0;
                        goto nodelete;
                }

                mod = xfs_rtb_to_rtxoff(mp, del.br_startblock);
                if (mod) {
                        xfs_extlen_t off = mp->m_sb.sb_rextsize - mod;

                        /*
                         * Realtime extent is lined up at the end but not
                         * at the front.  We'll get rid of full extents if
                         * we can.
                         */
                        if (del.br_blockcount > off) {
                                del.br_blockcount -= off;
                                del.br_startoff += off;
                                del.br_startblock += off;
                        } else if (del.br_startoff == start &&
                                   (del.br_state == XFS_EXT_UNWRITTEN ||
                                    tp->t_blk_res == 0)) {
                                /*
                                 * Can't make it unwritten.  There isn't
                                 * a full extent here so just skip it.
                                 */
                                ASSERT(end >= del.br_blockcount);
                                end -= del.br_blockcount;
                                if (got.br_startoff > end &&
                                    !xfs_iext_prev_extent(ifp, &icur, &got)) {
                                        done = true;
                                        break;
                                }
                                continue;
                        } else if (del.br_state == XFS_EXT_UNWRITTEN) {
                                struct xfs_bmbt_irec    prev;
                                xfs_fileoff_t           unwrite_start;

                                /*
                                 * This one is already unwritten.
                                 * It must have a written left neighbor.
                                 * Unwrite the killed part of that one and
                                 * try again.
                                 */
                                if (!xfs_iext_prev_extent(ifp, &icur, &prev))
                                        ASSERT(0);
                                ASSERT(prev.br_state == XFS_EXT_NORM);
                                ASSERT(!isnullstartblock(prev.br_startblock));
                                ASSERT(del.br_startblock ==
                                       prev.br_startblock + prev.br_blockcount);
                                unwrite_start = max3(start,
                                                     del.br_startoff - mod,
                                                     prev.br_startoff);
                                mod = unwrite_start - prev.br_startoff;
                                prev.br_startoff = unwrite_start;
                                prev.br_startblock += mod;
                                prev.br_blockcount -= mod;
                                prev.br_state = XFS_EXT_UNWRITTEN;
                                error = xfs_bmap_add_extent_unwritten_real(tp,
                                                ip, whichfork, &icur, &cur,
                                                &prev, &logflags);
                                if (error)
                                        goto error0;
                                goto nodelete;
                        } else {
                                ASSERT(del.br_state == XFS_EXT_NORM);
                                del.br_state = XFS_EXT_UNWRITTEN;
                                error = xfs_bmap_add_extent_unwritten_real(tp,
                                                ip, whichfork, &icur, &cur,
                                                &del, &logflags);
                                if (error)
                                        goto error0;
                                goto nodelete;
                        }
                }

delete:
                if (wasdel) {
                        xfs_bmap_del_extent_delay(ip, whichfork, &icur, &got,
                                        &del, flags);
                } else {
                        error = xfs_bmap_del_extent_real(ip, tp, &icur, cur,
                                        &del, &tmp_logflags, whichfork,
                                        flags);
                        logflags |= tmp_logflags;
                        if (error)
                                goto error0;
                }

                end = del.br_startoff - 1;
nodelete:
                /*
                 * If not done go on to the next (previous) record.
                 */
                if (end != (xfs_fileoff_t)-1 && end >= start) {
                        if (!xfs_iext_get_extent(ifp, &icur, &got) ||
                            (got.br_startoff > end &&
                             !xfs_iext_prev_extent(ifp, &icur, &got))) {
                                done = true;
                                break;
                        }
                        extno++;
                }
        }
        if (done || end == (xfs_fileoff_t)-1 || end < start)
                *rlen = 0;
        else
                *rlen = end - start + 1;

        /*
         * Convert to a btree if necessary.
         */
        if (xfs_bmap_needs_btree(ip, whichfork)) {
                ASSERT(cur == NULL);
                error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
                                &tmp_logflags, whichfork);
                logflags |= tmp_logflags;
        } else {
                error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags,
                        whichfork);
        }

error0:
        /*
         * Log everything.  Do this after conversion, there's no point in
         * logging the extent records if we've converted to btree format.
         */
        if ((logflags & xfs_ilog_fext(whichfork)) &&
            ifp->if_format != XFS_DINODE_FMT_EXTENTS)
                logflags &= ~xfs_ilog_fext(whichfork);
        else if ((logflags & xfs_ilog_fbroot(whichfork)) &&
                 ifp->if_format != XFS_DINODE_FMT_BTREE)
                logflags &= ~xfs_ilog_fbroot(whichfork);
        /*
         * Log inode even in the error case, if the transaction
         * is dirty we'll need to shut down the filesystem.
         */
        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        if (cur) {
                if (!error)
                        cur->bc_bmap.allocated = 0;
                xfs_btree_del_cursor(cur, error);
        }
        return error;
}

/* Unmap a range of a file. */
int
xfs_bunmapi(
        xfs_trans_t             *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           bno,
        xfs_filblks_t           len,
        uint32_t                flags,
        xfs_extnum_t            nexts,
        int                     *done)
{
        int                     error;

        error = __xfs_bunmapi(tp, ip, bno, &len, flags, nexts);
        *done = (len == 0);
        return error;
}

/*
 * Determine whether an extent shift can be accomplished by a merge with the
 * extent that precedes the target hole of the shift.
 */
STATIC bool
xfs_bmse_can_merge(
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *left,  /* preceding extent */
        struct xfs_bmbt_irec    *got,   /* current extent to shift */
        xfs_fileoff_t           shift)  /* shift fsb */
{
        xfs_fileoff_t           startoff;

        startoff = got->br_startoff - shift;

        /*
         * The extent, once shifted, must be adjacent in-file and on-disk with
         * the preceding extent.
         */
        if ((left->br_startoff + left->br_blockcount != startoff) ||
            (left->br_startblock + left->br_blockcount != got->br_startblock) ||
            (left->br_state != got->br_state) ||
            (left->br_blockcount + got->br_blockcount > XFS_MAX_BMBT_EXTLEN) ||
            !xfs_bmap_same_rtgroup(ip, whichfork, left, got))
                return false;

        return true;
}

/*
 * A bmap extent shift adjusts the file offset of an extent to fill a preceding
 * hole in the file. If an extent shift would result in the extent being fully
 * adjacent to the extent that currently precedes the hole, we can merge with
 * the preceding extent rather than do the shift.
 *
 * This function assumes the caller has verified a shift-by-merge is possible
 * with the provided extents via xfs_bmse_can_merge().
 */
STATIC int
xfs_bmse_merge(
        struct xfs_trans                *tp,
        struct xfs_inode                *ip,
        int                             whichfork,
        xfs_fileoff_t                   shift,          /* shift fsb */
        struct xfs_iext_cursor          *icur,
        struct xfs_bmbt_irec            *got,           /* extent to shift */
        struct xfs_bmbt_irec            *left,          /* preceding extent */
        struct xfs_btree_cur            *cur,
        int                             *logflags)      /* output */
{
        struct xfs_ifork                *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_bmbt_irec            new;
        xfs_filblks_t                   blockcount;
        int                             error, i;
        struct xfs_mount                *mp = ip->i_mount;

        blockcount = left->br_blockcount + got->br_blockcount;

        xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
        ASSERT(xfs_bmse_can_merge(ip, whichfork, left, got, shift));

        new = *left;
        new.br_blockcount = blockcount;

        /*
         * Update the on-disk extent count, the btree if necessary and log the
         * inode.
         */
        ifp->if_nextents--;
        *logflags |= XFS_ILOG_CORE;
        if (!cur) {
                *logflags |= XFS_ILOG_DEXT;
                goto done;
        }

        /* lookup and remove the extent to merge */
        error = xfs_bmbt_lookup_eq(cur, got, &i);
        if (error)
                return error;
        if (XFS_IS_CORRUPT(mp, i != 1)) {
                xfs_btree_mark_sick(cur);
                return -EFSCORRUPTED;
        }

        error = xfs_btree_delete(cur, &i);
        if (error)
                return error;
        if (XFS_IS_CORRUPT(mp, i != 1)) {
                xfs_btree_mark_sick(cur);
                return -EFSCORRUPTED;
        }

        /* lookup and update size of the previous extent */
        error = xfs_bmbt_lookup_eq(cur, left, &i);
        if (error)
                return error;
        if (XFS_IS_CORRUPT(mp, i != 1)) {
                xfs_btree_mark_sick(cur);
                return -EFSCORRUPTED;
        }

        error = xfs_bmbt_update(cur, &new);
        if (error)
                return error;

        /* change to extent format if required after extent removal */
        error = xfs_bmap_btree_to_extents(tp, ip, cur, logflags, whichfork);
        if (error)
                return error;

done:
        xfs_iext_remove(ip, icur, 0);
        xfs_iext_prev(ifp, icur);
        xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
                        &new);

        /* update reverse mapping. rmap functions merge the rmaps for us */
        xfs_rmap_unmap_extent(tp, ip, whichfork, got);
        memcpy(&new, got, sizeof(new));
        new.br_startoff = left->br_startoff + left->br_blockcount;
        xfs_rmap_map_extent(tp, ip, whichfork, &new);
        return 0;
}

static int
xfs_bmap_shift_update_extent(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_iext_cursor  *icur,
        struct xfs_bmbt_irec    *got,
        struct xfs_btree_cur    *cur,
        int                     *logflags,
        xfs_fileoff_t           startoff)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_bmbt_irec    prev = *got;
        int                     error, i;

        *logflags |= XFS_ILOG_CORE;

        got->br_startoff = startoff;

        if (cur) {
                error = xfs_bmbt_lookup_eq(cur, &prev, &i);
                if (error)
                        return error;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        return -EFSCORRUPTED;
                }

                error = xfs_bmbt_update(cur, got);
                if (error)
                        return error;
        } else {
                *logflags |= XFS_ILOG_DEXT;
        }

        xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
                        got);

        /* update reverse mapping */
        xfs_rmap_unmap_extent(tp, ip, whichfork, &prev);
        xfs_rmap_map_extent(tp, ip, whichfork, got);
        return 0;
}

int
xfs_bmap_collapse_extents(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           *next_fsb,
        xfs_fileoff_t           offset_shift_fsb,
        bool                    *done)
{
        int                     whichfork = XFS_DATA_FORK;
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_btree_cur    *cur = NULL;
        struct xfs_bmbt_irec    got, prev;
        struct xfs_iext_cursor  icur;
        xfs_fileoff_t           new_startoff;
        int                     error = 0;
        int                     logflags = 0;

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        if (ifp->if_format == XFS_DINODE_FMT_BTREE)
                cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);

        if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
                *done = true;
                goto del_cursor;
        }
        if (XFS_IS_CORRUPT(mp, isnullstartblock(got.br_startblock))) {
                xfs_bmap_mark_sick(ip, whichfork);
                error = -EFSCORRUPTED;
                goto del_cursor;
        }

        new_startoff = got.br_startoff - offset_shift_fsb;
        if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
                if (new_startoff < prev.br_startoff + prev.br_blockcount) {
                        error = -EINVAL;
                        goto del_cursor;
                }

                if (xfs_bmse_can_merge(ip, whichfork, &prev, &got,
                                offset_shift_fsb)) {
                        error = xfs_bmse_merge(tp, ip, whichfork,
                                        offset_shift_fsb, &icur, &got, &prev,
                                        cur, &logflags);
                        if (error)
                                goto del_cursor;
                        goto done;
                }
        } else {
                if (got.br_startoff < offset_shift_fsb) {
                        error = -EINVAL;
                        goto del_cursor;
                }
        }

        error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
                        cur, &logflags, new_startoff);
        if (error)
                goto del_cursor;

done:
        if (!xfs_iext_next_extent(ifp, &icur, &got)) {
                *done = true;
                goto del_cursor;
        }

        *next_fsb = got.br_startoff;
del_cursor:
        if (cur)
                xfs_btree_del_cursor(cur, error);
        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        return error;
}

/* Make sure we won't be right-shifting an extent past the maximum bound. */
int
xfs_bmap_can_insert_extents(
        struct xfs_inode        *ip,
        xfs_fileoff_t           off,
        xfs_fileoff_t           shift)
{
        struct xfs_bmbt_irec    got;
        int                     is_empty;
        int                     error = 0;

        xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL);

        if (xfs_is_shutdown(ip->i_mount))
                return -EIO;

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        error = xfs_bmap_last_extent(NULL, ip, XFS_DATA_FORK, &got, &is_empty);
        if (!error && !is_empty && got.br_startoff >= off &&
            ((got.br_startoff + shift) & BMBT_STARTOFF_MASK) < got.br_startoff)
                error = -EINVAL;
        xfs_iunlock(ip, XFS_ILOCK_EXCL);

        return error;
}

int
xfs_bmap_insert_extents(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           *next_fsb,
        xfs_fileoff_t           offset_shift_fsb,
        bool                    *done,
        xfs_fileoff_t           stop_fsb)
{
        int                     whichfork = XFS_DATA_FORK;
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_btree_cur    *cur = NULL;
        struct xfs_bmbt_irec    got, next;
        struct xfs_iext_cursor  icur;
        xfs_fileoff_t           new_startoff;
        int                     error = 0;
        int                     logflags = 0;

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);

        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        if (ifp->if_format == XFS_DINODE_FMT_BTREE)
                cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);

        if (*next_fsb == NULLFSBLOCK) {
                xfs_iext_last(ifp, &icur);
                if (!xfs_iext_get_extent(ifp, &icur, &got) ||
                    stop_fsb > got.br_startoff) {
                        *done = true;
                        goto del_cursor;
                }
        } else {
                if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
                        *done = true;
                        goto del_cursor;
                }
        }
        if (XFS_IS_CORRUPT(mp, isnullstartblock(got.br_startblock))) {
                xfs_bmap_mark_sick(ip, whichfork);
                error = -EFSCORRUPTED;
                goto del_cursor;
        }

        if (XFS_IS_CORRUPT(mp, stop_fsb > got.br_startoff)) {
                xfs_bmap_mark_sick(ip, whichfork);
                error = -EFSCORRUPTED;
                goto del_cursor;
        }

        new_startoff = got.br_startoff + offset_shift_fsb;
        if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
                if (new_startoff + got.br_blockcount > next.br_startoff) {
                        error = -EINVAL;
                        goto del_cursor;
                }

                /*
                 * Unlike a left shift (which involves a hole punch), a right
                 * shift does not modify extent neighbors in any way.  We should
                 * never find mergeable extents in this scenario.  Check anyways
                 * and warn if we encounter two extents that could be one.
                 */
                if (xfs_bmse_can_merge(ip, whichfork, &got, &next,
                                offset_shift_fsb))
                        WARN_ON_ONCE(1);
        }

        error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
                        cur, &logflags, new_startoff);
        if (error)
                goto del_cursor;

        if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
            stop_fsb >= got.br_startoff + got.br_blockcount) {
                *done = true;
                goto del_cursor;
        }

        *next_fsb = got.br_startoff;
del_cursor:
        if (cur)
                xfs_btree_del_cursor(cur, error);
        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        return error;
}

/*
 * Splits an extent into two extents at split_fsb block such that it is the
 * first block of the current_ext. @ext is a target extent to be split.
 * @split_fsb is a block where the extents is split.  If split_fsb lies in a
 * hole or the first block of extents, just return 0.
 */
int
xfs_bmap_split_extent(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           split_fsb)
{
        int                             whichfork = XFS_DATA_FORK;
        struct xfs_ifork                *ifp = xfs_ifork_ptr(ip, whichfork);
        struct xfs_btree_cur            *cur = NULL;
        struct xfs_bmbt_irec            got;
        struct xfs_bmbt_irec            new; /* split extent */
        struct xfs_mount                *mp = ip->i_mount;
        xfs_fsblock_t                   gotblkcnt; /* new block count for got */
        struct xfs_iext_cursor          icur;
        int                             error = 0;
        int                             logflags = 0;
        int                             i = 0;

        if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
                xfs_bmap_mark_sick(ip, whichfork);
                return -EFSCORRUPTED;
        }

        if (xfs_is_shutdown(mp))
                return -EIO;

        /* Read in all the extents */
        error = xfs_iread_extents(tp, ip, whichfork);
        if (error)
                return error;

        /*
         * If there are not extents, or split_fsb lies in a hole we are done.
         */
        if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
            got.br_startoff >= split_fsb)
                return 0;

        gotblkcnt = split_fsb - got.br_startoff;
        new.br_startoff = split_fsb;
        new.br_startblock = got.br_startblock + gotblkcnt;
        new.br_blockcount = got.br_blockcount - gotblkcnt;
        new.br_state = got.br_state;

        if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
                cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
                error = xfs_bmbt_lookup_eq(cur, &got, &i);
                if (error)
                        goto del_cursor;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        goto del_cursor;
                }
        }

        got.br_blockcount = gotblkcnt;
        xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
                        &got);

        logflags = XFS_ILOG_CORE;
        if (cur) {
                error = xfs_bmbt_update(cur, &got);
                if (error)
                        goto del_cursor;
        } else
                logflags |= XFS_ILOG_DEXT;

        /* Add new extent */
        xfs_iext_next(ifp, &icur);
        xfs_iext_insert(ip, &icur, &new, 0);
        ifp->if_nextents++;

        if (cur) {
                error = xfs_bmbt_lookup_eq(cur, &new, &i);
                if (error)
                        goto del_cursor;
                if (XFS_IS_CORRUPT(mp, i != 0)) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        goto del_cursor;
                }
                error = xfs_btree_insert(cur, &i);
                if (error)
                        goto del_cursor;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        goto del_cursor;
                }
        }

        /*
         * Convert to a btree if necessary.
         */
        if (xfs_bmap_needs_btree(ip, whichfork)) {
                int tmp_logflags; /* partial log flag return val */

                ASSERT(cur == NULL);
                error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
                                &tmp_logflags, whichfork);
                logflags |= tmp_logflags;
        }

del_cursor:
        if (cur) {
                cur->bc_bmap.allocated = 0;
                xfs_btree_del_cursor(cur, error);
        }

        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);
        return error;
}

/* Record a bmap intent. */
static inline void
__xfs_bmap_add(
        struct xfs_trans                *tp,
        enum xfs_bmap_intent_type       type,
        struct xfs_inode                *ip,
        int                             whichfork,
        struct xfs_bmbt_irec            *bmap)
{
        struct xfs_bmap_intent          *bi;

        if ((whichfork != XFS_DATA_FORK && whichfork != XFS_ATTR_FORK) ||
            bmap->br_startblock == HOLESTARTBLOCK ||
            bmap->br_startblock == DELAYSTARTBLOCK)
                return;

        bi = kmem_cache_alloc(xfs_bmap_intent_cache, GFP_KERNEL | __GFP_NOFAIL);
        INIT_LIST_HEAD(&bi->bi_list);
        bi->bi_type = type;
        bi->bi_owner = ip;
        bi->bi_whichfork = whichfork;
        bi->bi_bmap = *bmap;

        xfs_bmap_defer_add(tp, bi);
}

/* Map an extent into a file. */
void
xfs_bmap_map_extent(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *PREV)
{
        __xfs_bmap_add(tp, XFS_BMAP_MAP, ip, whichfork, PREV);
}

/* Unmap an extent out of a file. */
void
xfs_bmap_unmap_extent(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *PREV)
{
        __xfs_bmap_add(tp, XFS_BMAP_UNMAP, ip, whichfork, PREV);
}

/*
 * Process one of the deferred bmap operations.  We pass back the
 * btree cursor to maintain our lock on the bmapbt between calls.
 */
int
xfs_bmap_finish_one(
        struct xfs_trans                *tp,
        struct xfs_bmap_intent          *bi)
{
        struct xfs_bmbt_irec            *bmap = &bi->bi_bmap;
        int                             error = 0;
        int                             flags = 0;

        if (bi->bi_whichfork == XFS_ATTR_FORK)
                flags |= XFS_BMAPI_ATTRFORK;

        ASSERT(tp->t_highest_agno == NULLAGNUMBER);

        trace_xfs_bmap_deferred(bi);

        if (XFS_TEST_ERROR(tp->t_mountp, XFS_ERRTAG_BMAP_FINISH_ONE))
                return -EIO;

        switch (bi->bi_type) {
        case XFS_BMAP_MAP:
                if (bi->bi_bmap.br_state == XFS_EXT_UNWRITTEN)
                        flags |= XFS_BMAPI_PREALLOC;
                error = xfs_bmapi_remap(tp, bi->bi_owner, bmap->br_startoff,
                                bmap->br_blockcount, bmap->br_startblock,
                                flags);
                bmap->br_blockcount = 0;
                break;
        case XFS_BMAP_UNMAP:
                error = __xfs_bunmapi(tp, bi->bi_owner, bmap->br_startoff,
                                &bmap->br_blockcount, flags | XFS_BMAPI_REMAP,
                                1);
                break;
        default:
                ASSERT(0);
                xfs_bmap_mark_sick(bi->bi_owner, bi->bi_whichfork);
                error = -EFSCORRUPTED;
        }

        return error;
}

/* Check that an extent does not have invalid flags or bad ranges. */
xfs_failaddr_t
xfs_bmap_validate_extent_raw(
        struct xfs_mount        *mp,
        bool                    rtfile,
        int                     whichfork,
        struct xfs_bmbt_irec    *irec)
{
        if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
                return __this_address;

        if (rtfile && whichfork == XFS_DATA_FORK) {
                if (!xfs_verify_rtbext(mp, irec->br_startblock,
                                           irec->br_blockcount))
                        return __this_address;
        } else {
                if (!xfs_verify_fsbext(mp, irec->br_startblock,
                                           irec->br_blockcount))
                        return __this_address;
        }
        if (irec->br_state != XFS_EXT_NORM && whichfork != XFS_DATA_FORK)
                return __this_address;
        return NULL;
}

int __init
xfs_bmap_intent_init_cache(void)
{
        xfs_bmap_intent_cache = kmem_cache_create("xfs_bmap_intent",
                        sizeof(struct xfs_bmap_intent),
                        0, 0, NULL);

        return xfs_bmap_intent_cache != NULL ? 0 : -ENOMEM;
}

void
xfs_bmap_intent_destroy_cache(void)
{
        kmem_cache_destroy(xfs_bmap_intent_cache);
        xfs_bmap_intent_cache = NULL;
}

/* Check that an inode's extent does not have invalid flags or bad ranges. */
xfs_failaddr_t
xfs_bmap_validate_extent(
        struct xfs_inode        *ip,
        int                     whichfork,
        struct xfs_bmbt_irec    *irec)
{
        return xfs_bmap_validate_extent_raw(ip->i_mount,
                        XFS_IS_REALTIME_INODE(ip), whichfork, irec);
}

/*
 * Used in xfs_itruncate_extents().  This is the maximum number of extents
 * freed from a file in a single transaction.
 */
#define XFS_ITRUNC_MAX_EXTENTS  2

/*
 * Unmap every extent in part of an inode's fork.  We don't do any higher level
 * invalidation work at all.
 */
int
xfs_bunmapi_range(
        struct xfs_trans        **tpp,
        struct xfs_inode        *ip,
        uint32_t                flags,
        xfs_fileoff_t           startoff,
        xfs_fileoff_t           endoff)
{
        xfs_filblks_t           unmap_len = endoff - startoff + 1;
        int                     error = 0;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);

        while (unmap_len > 0) {
                ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
                error = __xfs_bunmapi(*tpp, ip, startoff, &unmap_len, flags,
                                XFS_ITRUNC_MAX_EXTENTS);
                if (error)
                        goto out;

                /* free the just unmapped extents */
                error = xfs_defer_finish(tpp);
                if (error)
                        goto out;
                cond_resched();
        }
out:
        return error;
}

struct xfs_bmap_query_range {
        xfs_bmap_query_range_fn fn;
        void                    *priv;
};

/* Format btree record and pass to our callback. */
STATIC int
xfs_bmap_query_range_helper(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_rec       *rec,
        void                            *priv)
{
        struct xfs_bmap_query_range     *query = priv;
        struct xfs_bmbt_irec            irec;
        xfs_failaddr_t                  fa;

        xfs_bmbt_disk_get_all(&rec->bmbt, &irec);
        fa = xfs_bmap_validate_extent(cur->bc_ino.ip, cur->bc_ino.whichfork,
                        &irec);
        if (fa) {
                xfs_btree_mark_sick(cur);
                return xfs_bmap_complain_bad_rec(cur->bc_ino.ip,
                                cur->bc_ino.whichfork, fa, &irec);
        }

        return query->fn(cur, &irec, query->priv);
}

/* Find all bmaps. */
int
xfs_bmap_query_all(
        struct xfs_btree_cur            *cur,
        xfs_bmap_query_range_fn         fn,
        void                            *priv)
{
        struct xfs_bmap_query_range     query = {
                .priv                   = priv,
                .fn                     = fn,
        };

        return xfs_btree_query_all(cur, xfs_bmap_query_range_helper, &query);
}

/* Helper function to extract extent size hint from inode */
xfs_extlen_t
xfs_get_extsz_hint(
        struct xfs_inode        *ip)
{
        /*
         * No point in aligning allocations if we need to COW to actually
         * write to them.
         */
        if (!xfs_is_always_cow_inode(ip) &&
            (ip->i_diflags & XFS_DIFLAG_EXTSIZE) && ip->i_extsize)
                return ip->i_extsize;
        if (XFS_IS_REALTIME_INODE(ip) &&
            ip->i_mount->m_sb.sb_rextsize > 1)
                return ip->i_mount->m_sb.sb_rextsize;
        return 0;
}

/*
 * Helper function to extract CoW extent size hint from inode.
 * Between the extent size hint and the CoW extent size hint, we
 * return the greater of the two.  If the value is zero (automatic),
 * use the default size.
 */
xfs_extlen_t
xfs_get_cowextsz_hint(
        struct xfs_inode        *ip)
{
        xfs_extlen_t            a, b;

        a = 0;
        if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
                a = ip->i_cowextsize;
        if (XFS_IS_REALTIME_INODE(ip)) {
                b = 0;
                if (ip->i_diflags & XFS_DIFLAG_EXTSIZE)
                        b = ip->i_extsize;
        } else {
                b = xfs_get_extsz_hint(ip);
        }

        a = max(a, b);
        if (a == 0)
                return XFS_DEFAULT_COWEXTSZ_HINT;
        return a;
}