// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2018-2024 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#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_inode.h"
#include "xfs_trans.h"
#include "xfs_alloc.h"
#include "xfs_btree.h"
#include "xfs_btree_staging.h"
#include "xfs_metafile.h"
#include "xfs_rmap.h"
#include "xfs_rtrmap_btree.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_error.h"
#include "xfs_extent_busy.h"
#include "xfs_rtgroup.h"
#include "xfs_bmap.h"
#include "xfs_health.h"
#include "xfs_buf_mem.h"
#include "xfs_btree_mem.h"

static struct kmem_cache        *xfs_rtrmapbt_cur_cache;

/*
 * Realtime Reverse Map btree.
 *
 * This is a btree used to track the owner(s) of a given extent in the realtime
 * device.  See the comments in xfs_rmap_btree.c for more information.
 *
 * This tree is basically the same as the regular rmap btree except that it
 * is rooted in an inode and does not live in free space.
 */

static struct xfs_btree_cur *
xfs_rtrmapbt_dup_cursor(
        struct xfs_btree_cur    *cur)
{
        return xfs_rtrmapbt_init_cursor(cur->bc_tp, to_rtg(cur->bc_group));
}

STATIC int
xfs_rtrmapbt_get_minrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level == cur->bc_nlevels - 1) {
                struct xfs_ifork        *ifp = xfs_btree_ifork_ptr(cur);

                return xfs_rtrmapbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
                                level == 0) / 2;
        }

        return cur->bc_mp->m_rtrmap_mnr[level != 0];
}

STATIC int
xfs_rtrmapbt_get_maxrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level == cur->bc_nlevels - 1) {
                struct xfs_ifork        *ifp = xfs_btree_ifork_ptr(cur);

                return xfs_rtrmapbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
                                level == 0);
        }

        return cur->bc_mp->m_rtrmap_mxr[level != 0];
}

/* Calculate number of records in the ondisk realtime rmap btree inode root. */
unsigned int
xfs_rtrmapbt_droot_maxrecs(
        unsigned int            blocklen,
        bool                    leaf)
{
        blocklen -= sizeof(struct xfs_rtrmap_root);

        if (leaf)
                return blocklen / sizeof(struct xfs_rmap_rec);
        return blocklen / (2 * sizeof(struct xfs_rmap_key) +
                        sizeof(xfs_rtrmap_ptr_t));
}

/*
 * Get the maximum records we could store in the on-disk format.
 *
 * For non-root nodes this is equivalent to xfs_rtrmapbt_get_maxrecs, but
 * for the root node this checks the available space in the dinode fork
 * so that we can resize the in-memory buffer to match it.  After a
 * resize to the maximum size this function returns the same value
 * as xfs_rtrmapbt_get_maxrecs for the root node, too.
 */
STATIC int
xfs_rtrmapbt_get_dmaxrecs(
        struct xfs_btree_cur    *cur,
        int                     level)
{
        if (level != cur->bc_nlevels - 1)
                return cur->bc_mp->m_rtrmap_mxr[level != 0];
        return xfs_rtrmapbt_droot_maxrecs(cur->bc_ino.forksize, level == 0);
}

/*
 * Convert the ondisk record's offset field into the ondisk key's offset field.
 * Fork and bmbt are significant parts of the rmap record key, but written
 * status is merely a record attribute.
 */
static inline __be64 ondisk_rec_offset_to_key(const union xfs_btree_rec *rec)
{
        return rec->rmap.rm_offset & ~cpu_to_be64(XFS_RMAP_OFF_UNWRITTEN);
}

STATIC void
xfs_rtrmapbt_init_key_from_rec(
        union xfs_btree_key             *key,
        const union xfs_btree_rec       *rec)
{
        key->rmap.rm_startblock = rec->rmap.rm_startblock;
        key->rmap.rm_owner = rec->rmap.rm_owner;
        key->rmap.rm_offset = ondisk_rec_offset_to_key(rec);
}

STATIC void
xfs_rtrmapbt_init_high_key_from_rec(
        union xfs_btree_key             *key,
        const union xfs_btree_rec       *rec)
{
        uint64_t                        off;
        int                             adj;

        adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;

        key->rmap.rm_startblock = rec->rmap.rm_startblock;
        be32_add_cpu(&key->rmap.rm_startblock, adj);
        key->rmap.rm_owner = rec->rmap.rm_owner;
        key->rmap.rm_offset = ondisk_rec_offset_to_key(rec);
        if (XFS_RMAP_NON_INODE_OWNER(be64_to_cpu(rec->rmap.rm_owner)) ||
            XFS_RMAP_IS_BMBT_BLOCK(be64_to_cpu(rec->rmap.rm_offset)))
                return;
        off = be64_to_cpu(key->rmap.rm_offset);
        off = (XFS_RMAP_OFF(off) + adj) | (off & ~XFS_RMAP_OFF_MASK);
        key->rmap.rm_offset = cpu_to_be64(off);
}

STATIC void
xfs_rtrmapbt_init_rec_from_cur(
        struct xfs_btree_cur    *cur,
        union xfs_btree_rec     *rec)
{
        rec->rmap.rm_startblock = cpu_to_be32(cur->bc_rec.r.rm_startblock);
        rec->rmap.rm_blockcount = cpu_to_be32(cur->bc_rec.r.rm_blockcount);
        rec->rmap.rm_owner = cpu_to_be64(cur->bc_rec.r.rm_owner);
        rec->rmap.rm_offset = cpu_to_be64(
                        xfs_rmap_irec_offset_pack(&cur->bc_rec.r));
}

STATIC void
xfs_rtrmapbt_init_ptr_from_cur(
        struct xfs_btree_cur    *cur,
        union xfs_btree_ptr     *ptr)
{
        ptr->l = 0;
}

/*
 * Mask the appropriate parts of the ondisk key field for a key comparison.
 * Fork and bmbt are significant parts of the rmap record key, but written
 * status is merely a record attribute.
 */
static inline uint64_t offset_keymask(uint64_t offset)
{
        return offset & ~XFS_RMAP_OFF_UNWRITTEN;
}

STATIC int
xfs_rtrmapbt_cmp_key_with_cur(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_key       *key)
{
        struct xfs_rmap_irec            *rec = &cur->bc_rec.r;
        const struct xfs_rmap_key       *kp = &key->rmap;

        return cmp_int(be32_to_cpu(kp->rm_startblock), rec->rm_startblock) ?:
               cmp_int(be64_to_cpu(kp->rm_owner), rec->rm_owner) ?:
               cmp_int(offset_keymask(be64_to_cpu(kp->rm_offset)),
                       offset_keymask(xfs_rmap_irec_offset_pack(rec)));
}

STATIC int
xfs_rtrmapbt_cmp_two_keys(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_key       *k1,
        const union xfs_btree_key       *k2,
        const union xfs_btree_key       *mask)
{
        const struct xfs_rmap_key       *kp1 = &k1->rmap;
        const struct xfs_rmap_key       *kp2 = &k2->rmap;
        int                             d;

        /* Doesn't make sense to mask off the physical space part */
        ASSERT(!mask || mask->rmap.rm_startblock);

        d = cmp_int(be32_to_cpu(kp1->rm_startblock),
                    be32_to_cpu(kp2->rm_startblock));
        if (d)
                return d;

        if (!mask || mask->rmap.rm_owner) {
                d = cmp_int(be64_to_cpu(kp1->rm_owner),
                            be64_to_cpu(kp2->rm_owner));
                if (d)
                        return d;
        }

        if (!mask || mask->rmap.rm_offset) {
                /* Doesn't make sense to allow offset but not owner */
                ASSERT(!mask || mask->rmap.rm_owner);

                d = cmp_int(offset_keymask(be64_to_cpu(kp1->rm_offset)),
                            offset_keymask(be64_to_cpu(kp2->rm_offset)));
                if (d)
                        return d;
        }

        return 0;
}

static xfs_failaddr_t
xfs_rtrmapbt_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_target->bt_mount;
        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
        xfs_failaddr_t          fa;
        int                     level;

        if (!xfs_verify_magic(bp, block->bb_magic))
                return __this_address;

        if (!xfs_has_rmapbt(mp))
                return __this_address;
        fa = xfs_btree_fsblock_v5hdr_verify(bp, XFS_RMAP_OWN_UNKNOWN);
        if (fa)
                return fa;
        level = be16_to_cpu(block->bb_level);
        if (level > mp->m_rtrmap_maxlevels)
                return __this_address;

        return xfs_btree_fsblock_verify(bp, mp->m_rtrmap_mxr[level != 0]);
}

static void
xfs_rtrmapbt_read_verify(
        struct xfs_buf  *bp)
{
        xfs_failaddr_t  fa;

        if (!xfs_btree_fsblock_verify_crc(bp))
                xfs_verifier_error(bp, -EFSBADCRC, __this_address);
        else {
                fa = xfs_rtrmapbt_verify(bp);
                if (fa)
                        xfs_verifier_error(bp, -EFSCORRUPTED, fa);
        }

        if (bp->b_error)
                trace_xfs_btree_corrupt(bp, _RET_IP_);
}

static void
xfs_rtrmapbt_write_verify(
        struct xfs_buf  *bp)
{
        xfs_failaddr_t  fa;

        fa = xfs_rtrmapbt_verify(bp);
        if (fa) {
                trace_xfs_btree_corrupt(bp, _RET_IP_);
                xfs_verifier_error(bp, -EFSCORRUPTED, fa);
                return;
        }
        xfs_btree_fsblock_calc_crc(bp);

}

const struct xfs_buf_ops xfs_rtrmapbt_buf_ops = {
        .name                   = "xfs_rtrmapbt",
        .magic                  = { 0, cpu_to_be32(XFS_RTRMAP_CRC_MAGIC) },
        .verify_read            = xfs_rtrmapbt_read_verify,
        .verify_write           = xfs_rtrmapbt_write_verify,
        .verify_struct          = xfs_rtrmapbt_verify,
};

STATIC int
xfs_rtrmapbt_keys_inorder(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_key       *k1,
        const union xfs_btree_key       *k2)
{
        uint32_t                        x;
        uint32_t                        y;
        uint64_t                        a;
        uint64_t                        b;

        x = be32_to_cpu(k1->rmap.rm_startblock);
        y = be32_to_cpu(k2->rmap.rm_startblock);
        if (x < y)
                return 1;
        else if (x > y)
                return 0;
        a = be64_to_cpu(k1->rmap.rm_owner);
        b = be64_to_cpu(k2->rmap.rm_owner);
        if (a < b)
                return 1;
        else if (a > b)
                return 0;
        a = offset_keymask(be64_to_cpu(k1->rmap.rm_offset));
        b = offset_keymask(be64_to_cpu(k2->rmap.rm_offset));
        if (a <= b)
                return 1;
        return 0;
}

STATIC int
xfs_rtrmapbt_recs_inorder(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_rec       *r1,
        const union xfs_btree_rec       *r2)
{
        uint32_t                        x;
        uint32_t                        y;
        uint64_t                        a;
        uint64_t                        b;

        x = be32_to_cpu(r1->rmap.rm_startblock);
        y = be32_to_cpu(r2->rmap.rm_startblock);
        if (x < y)
                return 1;
        else if (x > y)
                return 0;
        a = be64_to_cpu(r1->rmap.rm_owner);
        b = be64_to_cpu(r2->rmap.rm_owner);
        if (a < b)
                return 1;
        else if (a > b)
                return 0;
        a = offset_keymask(be64_to_cpu(r1->rmap.rm_offset));
        b = offset_keymask(be64_to_cpu(r2->rmap.rm_offset));
        if (a <= b)
                return 1;
        return 0;
}

STATIC enum xbtree_key_contig
xfs_rtrmapbt_keys_contiguous(
        struct xfs_btree_cur            *cur,
        const union xfs_btree_key       *key1,
        const union xfs_btree_key       *key2,
        const union xfs_btree_key       *mask)
{
        ASSERT(!mask || mask->rmap.rm_startblock);

        /*
         * We only support checking contiguity of the physical space component.
         * If any callers ever need more specificity than that, they'll have to
         * implement it here.
         */
        ASSERT(!mask || (!mask->rmap.rm_owner && !mask->rmap.rm_offset));

        return xbtree_key_contig(be32_to_cpu(key1->rmap.rm_startblock),
                                 be32_to_cpu(key2->rmap.rm_startblock));
}

static inline void
xfs_rtrmapbt_move_ptrs(
        struct xfs_mount        *mp,
        struct xfs_btree_block  *broot,
        short                   old_size,
        size_t                  new_size,
        unsigned int            numrecs)
{
        void                    *dptr;
        void                    *sptr;

        sptr = xfs_rtrmap_broot_ptr_addr(mp, broot, 1, old_size);
        dptr = xfs_rtrmap_broot_ptr_addr(mp, broot, 1, new_size);
        memmove(dptr, sptr, numrecs * sizeof(xfs_rtrmap_ptr_t));
}

static struct xfs_btree_block *
xfs_rtrmapbt_broot_realloc(
        struct xfs_btree_cur    *cur,
        unsigned int            new_numrecs)
{
        struct xfs_mount        *mp = cur->bc_mp;
        struct xfs_ifork        *ifp = xfs_btree_ifork_ptr(cur);
        struct xfs_btree_block  *broot;
        unsigned int            new_size;
        unsigned int            old_size = ifp->if_broot_bytes;
        const unsigned int      level = cur->bc_nlevels - 1;

        new_size = xfs_rtrmap_broot_space_calc(mp, level, new_numrecs);

        /* Handle the nop case quietly. */
        if (new_size == old_size)
                return ifp->if_broot;

        if (new_size > old_size) {
                unsigned int    old_numrecs;

                /*
                 * If there wasn't any memory allocated before, just allocate
                 * it now and get out.
                 */
                if (old_size == 0)
                        return xfs_broot_realloc(ifp, new_size);

                /*
                 * If there is already an existing if_broot, then we need to
                 * realloc it and possibly move the node block pointers because
                 * those are not butted up against the btree block header.
                 */
                old_numrecs = xfs_rtrmapbt_maxrecs(mp, old_size, level == 0);
                broot = xfs_broot_realloc(ifp, new_size);
                if (level > 0)
                        xfs_rtrmapbt_move_ptrs(mp, broot, old_size, new_size,
                                        old_numrecs);
                goto out_broot;
        }

        /*
         * We're reducing numrecs.  If we're going all the way to zero, just
         * free the block.
         */
        ASSERT(ifp->if_broot != NULL && old_size > 0);
        if (new_size == 0)
                return xfs_broot_realloc(ifp, 0);

        /*
         * Shrink the btree root by possibly moving the rtrmapbt pointers,
         * since they are not butted up against the btree block header.  Then
         * reallocate broot.
         */
        if (level > 0)
                xfs_rtrmapbt_move_ptrs(mp, ifp->if_broot, old_size, new_size,
                                new_numrecs);
        broot = xfs_broot_realloc(ifp, new_size);

out_broot:
        ASSERT(xfs_rtrmap_droot_space(broot) <=
               xfs_inode_fork_size(cur->bc_ino.ip, cur->bc_ino.whichfork));
        return broot;
}

const struct xfs_btree_ops xfs_rtrmapbt_ops = {
        .name                   = "rtrmap",
        .type                   = XFS_BTREE_TYPE_INODE,
        .geom_flags             = XFS_BTGEO_OVERLAPPING |
                                  XFS_BTGEO_IROOT_RECORDS,

        .rec_len                = sizeof(struct xfs_rmap_rec),
        /* Overlapping btree; 2 keys per pointer. */
        .key_len                = 2 * sizeof(struct xfs_rmap_key),
        .ptr_len                = XFS_BTREE_LONG_PTR_LEN,

        .lru_refs               = XFS_RMAP_BTREE_REF,
        .statoff                = XFS_STATS_CALC_INDEX(xs_rtrmap_2),
        .sick_mask              = XFS_SICK_RG_RMAPBT,

        .dup_cursor             = xfs_rtrmapbt_dup_cursor,
        .alloc_block            = xfs_btree_alloc_metafile_block,
        .free_block             = xfs_btree_free_metafile_block,
        .get_minrecs            = xfs_rtrmapbt_get_minrecs,
        .get_maxrecs            = xfs_rtrmapbt_get_maxrecs,
        .get_dmaxrecs           = xfs_rtrmapbt_get_dmaxrecs,
        .init_key_from_rec      = xfs_rtrmapbt_init_key_from_rec,
        .init_high_key_from_rec = xfs_rtrmapbt_init_high_key_from_rec,
        .init_rec_from_cur      = xfs_rtrmapbt_init_rec_from_cur,
        .init_ptr_from_cur      = xfs_rtrmapbt_init_ptr_from_cur,
        .cmp_key_with_cur       = xfs_rtrmapbt_cmp_key_with_cur,
        .buf_ops                = &xfs_rtrmapbt_buf_ops,
        .cmp_two_keys           = xfs_rtrmapbt_cmp_two_keys,
        .keys_inorder           = xfs_rtrmapbt_keys_inorder,
        .recs_inorder           = xfs_rtrmapbt_recs_inorder,
        .keys_contiguous        = xfs_rtrmapbt_keys_contiguous,
        .broot_realloc          = xfs_rtrmapbt_broot_realloc,
};

/* Allocate a new rt rmap btree cursor. */
struct xfs_btree_cur *
xfs_rtrmapbt_init_cursor(
        struct xfs_trans        *tp,
        struct xfs_rtgroup      *rtg)
{
        struct xfs_inode        *ip = rtg_rmap(rtg);
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_btree_cur    *cur;

        xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);

        cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rtrmapbt_ops,
                        mp->m_rtrmap_maxlevels, xfs_rtrmapbt_cur_cache);

        cur->bc_ino.ip = ip;
        cur->bc_group = xfs_group_hold(rtg_group(rtg));
        cur->bc_ino.whichfork = XFS_DATA_FORK;
        cur->bc_nlevels = be16_to_cpu(ip->i_df.if_broot->bb_level) + 1;
        cur->bc_ino.forksize = xfs_inode_fork_size(ip, XFS_DATA_FORK);

        return cur;
}

#ifdef CONFIG_XFS_BTREE_IN_MEM
/*
 * Validate an in-memory realtime rmap btree block.  Callers are allowed to
 * generate an in-memory btree even if the ondisk feature is not enabled.
 */
static xfs_failaddr_t
xfs_rtrmapbt_mem_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_mount;
        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
        xfs_failaddr_t          fa;
        unsigned int            level;
        unsigned int            maxrecs;

        if (!xfs_verify_magic(bp, block->bb_magic))
                return __this_address;

        fa = xfs_btree_fsblock_v5hdr_verify(bp, XFS_RMAP_OWN_UNKNOWN);
        if (fa)
                return fa;

        level = be16_to_cpu(block->bb_level);
        if (xfs_has_rmapbt(mp)) {
                if (level >= mp->m_rtrmap_maxlevels)
                        return __this_address;
        } else {
                if (level >= xfs_rtrmapbt_maxlevels_ondisk())
                        return __this_address;
        }

        maxrecs = xfs_rtrmapbt_maxrecs(mp, XFBNO_BLOCKSIZE, level == 0);
        return xfs_btree_memblock_verify(bp, maxrecs);
}

static void
xfs_rtrmapbt_mem_rw_verify(
        struct xfs_buf  *bp)
{
        xfs_failaddr_t  fa = xfs_rtrmapbt_mem_verify(bp);

        if (fa)
                xfs_verifier_error(bp, -EFSCORRUPTED, fa);
}

/* skip crc checks on in-memory btrees to save time */
static const struct xfs_buf_ops xfs_rtrmapbt_mem_buf_ops = {
        .name                   = "xfs_rtrmapbt_mem",
        .magic                  = { 0, cpu_to_be32(XFS_RTRMAP_CRC_MAGIC) },
        .verify_read            = xfs_rtrmapbt_mem_rw_verify,
        .verify_write           = xfs_rtrmapbt_mem_rw_verify,
        .verify_struct          = xfs_rtrmapbt_mem_verify,
};

const struct xfs_btree_ops xfs_rtrmapbt_mem_ops = {
        .type                   = XFS_BTREE_TYPE_MEM,
        .geom_flags             = XFS_BTGEO_OVERLAPPING,

        .rec_len                = sizeof(struct xfs_rmap_rec),
        /* Overlapping btree; 2 keys per pointer. */
        .key_len                = 2 * sizeof(struct xfs_rmap_key),
        .ptr_len                = XFS_BTREE_LONG_PTR_LEN,

        .lru_refs               = XFS_RMAP_BTREE_REF,
        .statoff                = XFS_STATS_CALC_INDEX(xs_rtrmap_mem_2),

        .dup_cursor             = xfbtree_dup_cursor,
        .set_root               = xfbtree_set_root,
        .alloc_block            = xfbtree_alloc_block,
        .free_block             = xfbtree_free_block,
        .get_minrecs            = xfbtree_get_minrecs,
        .get_maxrecs            = xfbtree_get_maxrecs,
        .init_key_from_rec      = xfs_rtrmapbt_init_key_from_rec,
        .init_high_key_from_rec = xfs_rtrmapbt_init_high_key_from_rec,
        .init_rec_from_cur      = xfs_rtrmapbt_init_rec_from_cur,
        .init_ptr_from_cur      = xfbtree_init_ptr_from_cur,
        .cmp_key_with_cur       = xfs_rtrmapbt_cmp_key_with_cur,
        .buf_ops                = &xfs_rtrmapbt_mem_buf_ops,
        .cmp_two_keys           = xfs_rtrmapbt_cmp_two_keys,
        .keys_inorder           = xfs_rtrmapbt_keys_inorder,
        .recs_inorder           = xfs_rtrmapbt_recs_inorder,
        .keys_contiguous        = xfs_rtrmapbt_keys_contiguous,
};

/* Create a cursor for an in-memory btree. */
struct xfs_btree_cur *
xfs_rtrmapbt_mem_cursor(
        struct xfs_rtgroup      *rtg,
        struct xfs_trans        *tp,
        struct xfbtree          *xfbt)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_btree_cur    *cur;

        cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rtrmapbt_mem_ops,
                        mp->m_rtrmap_maxlevels, xfs_rtrmapbt_cur_cache);
        cur->bc_mem.xfbtree = xfbt;
        cur->bc_nlevels = xfbt->nlevels;
        cur->bc_group = xfs_group_hold(rtg_group(rtg));
        return cur;
}

/* Create an in-memory realtime rmap btree. */
int
xfs_rtrmapbt_mem_init(
        struct xfs_mount        *mp,
        struct xfbtree          *xfbt,
        struct xfs_buftarg      *btp,
        xfs_rgnumber_t          rgno)
{
        xfbt->owner = rgno;
        return xfbtree_init(mp, xfbt, btp, &xfs_rtrmapbt_mem_ops);
}
#endif /* CONFIG_XFS_BTREE_IN_MEM */

/*
 * Install a new rt reverse mapping btree root.  Caller is responsible for
 * invalidating and freeing the old btree blocks.
 */
void
xfs_rtrmapbt_commit_staged_btree(
        struct xfs_btree_cur    *cur,
        struct xfs_trans        *tp)
{
        struct xbtree_ifakeroot *ifake = cur->bc_ino.ifake;
        struct xfs_ifork        *ifp;
        int                     flags = XFS_ILOG_CORE | XFS_ILOG_DBROOT;

        ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
        ASSERT(ifake->if_fork->if_format == XFS_DINODE_FMT_META_BTREE);

        /*
         * Free any resources hanging off the real fork, then shallow-copy the
         * staging fork's contents into the real fork to transfer everything
         * we just built.
         */
        ifp = xfs_ifork_ptr(cur->bc_ino.ip, XFS_DATA_FORK);
        xfs_idestroy_fork(ifp);
        memcpy(ifp, ifake->if_fork, sizeof(struct xfs_ifork));

        cur->bc_ino.ip->i_projid = cur->bc_group->xg_gno;
        xfs_trans_log_inode(tp, cur->bc_ino.ip, flags);
        xfs_btree_commit_ifakeroot(cur, tp, XFS_DATA_FORK);
}

/* Calculate number of records in a rt reverse mapping btree block. */
static inline unsigned int
xfs_rtrmapbt_block_maxrecs(
        unsigned int            blocklen,
        bool                    leaf)
{
        if (leaf)
                return blocklen / sizeof(struct xfs_rmap_rec);
        return blocklen /
                (2 * sizeof(struct xfs_rmap_key) + sizeof(xfs_rtrmap_ptr_t));
}

/*
 * Calculate number of records in an rt reverse mapping btree block.
 */
unsigned int
xfs_rtrmapbt_maxrecs(
        struct xfs_mount        *mp,
        unsigned int            blocklen,
        bool                    leaf)
{
        blocklen -= XFS_RTRMAP_BLOCK_LEN;
        return xfs_rtrmapbt_block_maxrecs(blocklen, leaf);
}

/* Compute the max possible height for realtime reverse mapping btrees. */
unsigned int
xfs_rtrmapbt_maxlevels_ondisk(void)
{
        unsigned long long      max_dblocks;
        unsigned int            minrecs[2];
        unsigned int            blocklen;

        blocklen = XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN;

        minrecs[0] = xfs_rtrmapbt_block_maxrecs(blocklen, true) / 2;
        minrecs[1] = xfs_rtrmapbt_block_maxrecs(blocklen, false) / 2;

        /*
         * Compute the asymptotic maxlevels for an rtrmapbt on any rtreflink fs.
         *
         * On a reflink filesystem, each block in an rtgroup can have up to
         * 2^32 (per the refcount record format) owners, which means that
         * theoretically we could face up to 2^64 rmap records.  However, we're
         * likely to run out of blocks in the data device long before that
         * happens, which means that we must compute the max height based on
         * what the btree will look like if it consumes almost all the blocks
         * in the data device due to maximal sharing factor.
         */
        max_dblocks = -1U; /* max ag count */
        max_dblocks *= XFS_MAX_CRC_AG_BLOCKS;
        return xfs_btree_space_to_height(minrecs, max_dblocks);
}

int __init
xfs_rtrmapbt_init_cur_cache(void)
{
        xfs_rtrmapbt_cur_cache = kmem_cache_create("xfs_rtrmapbt_cur",
                        xfs_btree_cur_sizeof(xfs_rtrmapbt_maxlevels_ondisk()),
                        0, 0, NULL);

        if (!xfs_rtrmapbt_cur_cache)
                return -ENOMEM;
        return 0;
}

void
xfs_rtrmapbt_destroy_cur_cache(void)
{
        kmem_cache_destroy(xfs_rtrmapbt_cur_cache);
        xfs_rtrmapbt_cur_cache = NULL;
}

/* Compute the maximum height of an rt reverse mapping btree. */
void
xfs_rtrmapbt_compute_maxlevels(
        struct xfs_mount        *mp)
{
        unsigned int            d_maxlevels, r_maxlevels;

        if (!xfs_has_rtrmapbt(mp)) {
                mp->m_rtrmap_maxlevels = 0;
                return;
        }

        /*
         * The realtime rmapbt lives on the data device, which means that its
         * maximum height is constrained by the size of the data device and
         * the height required to store one rmap record for each block in an
         * rt group.
         *
         * On a reflink filesystem, each rt block can have up to 2^32 (per the
         * refcount record format) owners, which means that theoretically we
         * could face up to 2^64 rmap records.  This makes the computation of
         * maxlevels based on record count meaningless, so we only consider the
         * size of the data device.
         */
        d_maxlevels = xfs_btree_space_to_height(mp->m_rtrmap_mnr,
                                mp->m_sb.sb_dblocks);
        if (xfs_has_rtreflink(mp)) {
                mp->m_rtrmap_maxlevels = d_maxlevels + 1;
                return;
        }

        r_maxlevels = xfs_btree_compute_maxlevels(mp->m_rtrmap_mnr,
                                mp->m_groups[XG_TYPE_RTG].blocks);

        /* Add one level to handle the inode root level. */
        mp->m_rtrmap_maxlevels = min(d_maxlevels, r_maxlevels) + 1;
}

/* Calculate the rtrmap btree size for some records. */
unsigned long long
xfs_rtrmapbt_calc_size(
        struct xfs_mount        *mp,
        unsigned long long      len)
{
        return xfs_btree_calc_size(mp->m_rtrmap_mnr, len);
}

/*
 * Calculate the maximum rmap btree size.
 */
static unsigned long long
xfs_rtrmapbt_max_size(
        struct xfs_mount        *mp,
        xfs_rtblock_t           rtblocks)
{
        /* Bail out if we're uninitialized, which can happen in mkfs. */
        if (mp->m_rtrmap_mxr[0] == 0)
                return 0;

        return xfs_rtrmapbt_calc_size(mp, rtblocks);
}

/*
 * Figure out how many blocks to reserve and how many are used by this btree.
 */
xfs_filblks_t
xfs_rtrmapbt_calc_reserves(
        struct xfs_mount        *mp)
{
        uint32_t                blocks = mp->m_groups[XG_TYPE_RTG].blocks;

        if (!xfs_has_rtrmapbt(mp))
                return 0;

        /* Reserve 1% of the rtgroup or enough for 1 block per record. */
        return max_t(xfs_filblks_t, blocks / 100,
                        xfs_rtrmapbt_max_size(mp, blocks));
}

/* Convert on-disk form of btree root to in-memory form. */
STATIC void
xfs_rtrmapbt_from_disk(
        struct xfs_inode        *ip,
        struct xfs_rtrmap_root  *dblock,
        unsigned int            dblocklen,
        struct xfs_btree_block  *rblock)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_rmap_key     *fkp;
        __be64                  *fpp;
        struct xfs_rmap_key     *tkp;
        __be64                  *tpp;
        struct xfs_rmap_rec     *frp;
        struct xfs_rmap_rec     *trp;
        unsigned int            rblocklen = xfs_rtrmap_broot_space(mp, dblock);
        unsigned int            numrecs;
        unsigned int            maxrecs;

        xfs_btree_init_block(mp, rblock, &xfs_rtrmapbt_ops, 0, 0, ip->i_ino);

        rblock->bb_level = dblock->bb_level;
        rblock->bb_numrecs = dblock->bb_numrecs;
        numrecs = be16_to_cpu(dblock->bb_numrecs);

        if (be16_to_cpu(rblock->bb_level) > 0) {
                maxrecs = xfs_rtrmapbt_droot_maxrecs(dblocklen, false);
                fkp = xfs_rtrmap_droot_key_addr(dblock, 1);
                tkp = xfs_rtrmap_key_addr(rblock, 1);
                fpp = xfs_rtrmap_droot_ptr_addr(dblock, 1, maxrecs);
                tpp = xfs_rtrmap_broot_ptr_addr(mp, rblock, 1, rblocklen);
                memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
                memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
        } else {
                frp = xfs_rtrmap_droot_rec_addr(dblock, 1);
                trp = xfs_rtrmap_rec_addr(rblock, 1);
                memcpy(trp, frp, sizeof(*frp) * numrecs);
        }
}

/* Load a realtime reverse mapping btree root in from disk. */
int
xfs_iformat_rtrmap(
        struct xfs_inode        *ip,
        struct xfs_dinode       *dip)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_rtrmap_root  *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
        struct xfs_btree_block  *broot;
        unsigned int            numrecs;
        unsigned int            level;
        int                     dsize;

        /*
         * growfs must create the rtrmap inodes before adding a realtime volume
         * to the filesystem, so we cannot use the rtrmapbt predicate here.
         */
        if (!xfs_has_rmapbt(ip->i_mount)) {
                xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
                return -EFSCORRUPTED;
        }

        dsize = XFS_DFORK_SIZE(dip, mp, XFS_DATA_FORK);
        numrecs = be16_to_cpu(dfp->bb_numrecs);
        level = be16_to_cpu(dfp->bb_level);

        if (level > mp->m_rtrmap_maxlevels ||
            xfs_rtrmap_droot_space_calc(level, numrecs) > dsize) {
                xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
                return -EFSCORRUPTED;
        }

        broot = xfs_broot_alloc(xfs_ifork_ptr(ip, XFS_DATA_FORK),
                        xfs_rtrmap_broot_space_calc(mp, level, numrecs));
        if (broot)
                xfs_rtrmapbt_from_disk(ip, dfp, dsize, broot);
        return 0;
}

/* Convert in-memory form of btree root to on-disk form. */
void
xfs_rtrmapbt_to_disk(
        struct xfs_mount        *mp,
        struct xfs_btree_block  *rblock,
        unsigned int            rblocklen,
        struct xfs_rtrmap_root  *dblock,
        unsigned int            dblocklen)
{
        struct xfs_rmap_key     *fkp;
        __be64                  *fpp;
        struct xfs_rmap_key     *tkp;
        __be64                  *tpp;
        struct xfs_rmap_rec     *frp;
        struct xfs_rmap_rec     *trp;
        unsigned int            numrecs;
        unsigned int            maxrecs;

        ASSERT(rblock->bb_magic == cpu_to_be32(XFS_RTRMAP_CRC_MAGIC));
        ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid));
        ASSERT(rblock->bb_u.l.bb_blkno == cpu_to_be64(XFS_BUF_DADDR_NULL));
        ASSERT(rblock->bb_u.l.bb_leftsib == cpu_to_be64(NULLFSBLOCK));
        ASSERT(rblock->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK));

        dblock->bb_level = rblock->bb_level;
        dblock->bb_numrecs = rblock->bb_numrecs;
        numrecs = be16_to_cpu(rblock->bb_numrecs);

        if (be16_to_cpu(rblock->bb_level) > 0) {
                maxrecs = xfs_rtrmapbt_droot_maxrecs(dblocklen, false);
                fkp = xfs_rtrmap_key_addr(rblock, 1);
                tkp = xfs_rtrmap_droot_key_addr(dblock, 1);
                fpp = xfs_rtrmap_broot_ptr_addr(mp, rblock, 1, rblocklen);
                tpp = xfs_rtrmap_droot_ptr_addr(dblock, 1, maxrecs);
                memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
                memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
        } else {
                frp = xfs_rtrmap_rec_addr(rblock, 1);
                trp = xfs_rtrmap_droot_rec_addr(dblock, 1);
                memcpy(trp, frp, sizeof(*frp) * numrecs);
        }
}

/* Flush a realtime reverse mapping btree root out to disk. */
void
xfs_iflush_rtrmap(
        struct xfs_inode        *ip,
        struct xfs_dinode       *dip)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
        struct xfs_rtrmap_root  *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);

        ASSERT(ifp->if_broot != NULL);
        ASSERT(ifp->if_broot_bytes > 0);
        ASSERT(xfs_rtrmap_droot_space(ifp->if_broot) <=
                        xfs_inode_fork_size(ip, XFS_DATA_FORK));
        xfs_rtrmapbt_to_disk(ip->i_mount, ifp->if_broot, ifp->if_broot_bytes,
                        dfp, XFS_DFORK_SIZE(dip, ip->i_mount, XFS_DATA_FORK));
}

/*
 * Create a realtime rmap btree inode.
 */
int
xfs_rtrmapbt_create(
        struct xfs_rtgroup      *rtg,
        struct xfs_inode        *ip,
        struct xfs_trans        *tp,
        bool                    init)
{
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_btree_block  *broot;

        ifp->if_format = XFS_DINODE_FMT_META_BTREE;
        ASSERT(ifp->if_broot_bytes == 0);
        ASSERT(ifp->if_bytes == 0);

        /* Initialize the empty incore btree root. */
        broot = xfs_broot_realloc(ifp, xfs_rtrmap_broot_space_calc(mp, 0, 0));
        if (broot)
                xfs_btree_init_block(mp, broot, &xfs_rtrmapbt_ops, 0, 0,
                                ip->i_ino);
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE | XFS_ILOG_DBROOT);

        return 0;
}

/*
 * Initialize an rmap for a realtime superblock using the potentially updated
 * rt geometry in the provided @mp.
 */
int
xfs_rtrmapbt_init_rtsb(
        struct xfs_mount        *mp,
        struct xfs_rtgroup      *rtg,
        struct xfs_trans        *tp)
{
        struct xfs_rmap_irec    rmap = {
                .rm_blockcount  = mp->m_sb.sb_rextsize,
                .rm_owner       = XFS_RMAP_OWN_FS,
        };
        struct xfs_btree_cur    *cur;
        int                     error;

        ASSERT(xfs_has_rtsb(mp));
        ASSERT(rtg_rgno(rtg) == 0);

        cur = xfs_rtrmapbt_init_cursor(tp, rtg);
        error = xfs_rmap_map_raw(cur, &rmap);
        xfs_btree_del_cursor(cur, error);
        return error;
}

/*
 * Return the highest rgbno currently tracked by the rmap for this rtg.
 */
xfs_rgblock_t
xfs_rtrmap_highest_rgbno(
        struct xfs_rtgroup      *rtg)
{
        struct xfs_btree_block  *block = rtg_rmap(rtg)->i_df.if_broot;
        union xfs_btree_key     key = {};
        struct xfs_btree_cur    *cur;

        if (block->bb_numrecs == 0)
                return NULLRGBLOCK;
        cur = xfs_rtrmapbt_init_cursor(NULL, rtg);
        xfs_btree_get_keys(cur, block, &key);
        xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
        return be32_to_cpu(key.__rmap_bigkey[1].rm_startblock);
}