// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 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_mount.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap_util.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_icache.h"
#include "xfs_rtalloc.h"
#include "xfs_sb.h"
#include "xfs_rtbitmap.h"
#include "xfs_rtrmap_btree.h"
#include "xfs_quota.h"
#include "xfs_log_priv.h"
#include "xfs_health.h"
#include "xfs_da_format.h"
#include "xfs_metafile.h"
#include "xfs_rtgroup.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_rtrefcount_btree.h"
#include "xfs_reflink.h"
#include "xfs_zone_alloc.h"

/*
 * Return whether there are any free extents in the size range given
 * by low and high, for the bitmap block bbno.
 */
STATIC int
xfs_rtany_summary(
        struct xfs_rtalloc_args *args,
        int                     low,    /* low log2 extent size */
        int                     high,   /* high log2 extent size */
        xfs_fileoff_t           bbno,   /* bitmap block number */
        int                     *maxlog) /* out: max log2 extent size free */
{
        uint8_t                 *rsum_cache = args->rtg->rtg_rsum_cache;
        int                     error;
        int                     log;    /* loop counter, log2 of ext. size */
        xfs_suminfo_t           sum;    /* summary data */

        /* There are no extents at levels >= rsum_cache[bbno]. */
        if (rsum_cache) {
                high = min(high, rsum_cache[bbno] - 1);
                if (low > high) {
                        *maxlog = -1;
                        return 0;
                }
        }

        /*
         * Loop over logs of extent sizes.
         */
        for (log = high; log >= low; log--) {
                /*
                 * Get one summary datum.
                 */
                error = xfs_rtget_summary(args, log, bbno, &sum);
                if (error) {
                        return error;
                }
                /*
                 * If there are any, return success.
                 */
                if (sum) {
                        *maxlog = log;
                        goto out;
                }
        }
        /*
         * Found nothing, return failure.
         */
        *maxlog = -1;
out:
        /* There were no extents at levels > log. */
        if (rsum_cache && log + 1 < rsum_cache[bbno])
                rsum_cache[bbno] = log + 1;
        return 0;
}

/*
 * Copy and transform the summary file, given the old and new
 * parameters in the mount structures.
 */
STATIC int
xfs_rtcopy_summary(
        struct xfs_rtalloc_args *oargs,
        struct xfs_rtalloc_args *nargs)
{
        xfs_fileoff_t           bbno;   /* bitmap block number */
        int                     error;
        int                     log;    /* summary level number (log length) */
        xfs_suminfo_t           sum;    /* summary data */

        for (log = oargs->mp->m_rsumlevels - 1; log >= 0; log--) {
                for (bbno = oargs->mp->m_sb.sb_rbmblocks - 1;
                     (xfs_srtblock_t)bbno >= 0;
                     bbno--) {
                        error = xfs_rtget_summary(oargs, log, bbno, &sum);
                        if (error)
                                goto out;
                        if (XFS_IS_CORRUPT(oargs->mp, sum < 0)) {
                                error = -EFSCORRUPTED;
                                goto out;
                        }
                        if (sum == 0)
                                continue;
                        error = xfs_rtmodify_summary(oargs, log, bbno, -sum);
                        if (error)
                                goto out;
                        error = xfs_rtmodify_summary(nargs, log, bbno, sum);
                        if (error)
                                goto out;
                }
        }
        error = 0;
out:
        xfs_rtbuf_cache_relse(oargs);
        return error;
}
/*
 * Mark an extent specified by start and len allocated.
 * Updates all the summary information as well as the bitmap.
 */
STATIC int
xfs_rtallocate_range(
        struct xfs_rtalloc_args *args,
        xfs_rtxnum_t            start,  /* start rtext to allocate */
        xfs_rtxlen_t            len)    /* in/out: summary block number */
{
        struct xfs_mount        *mp = args->mp;
        xfs_rtxnum_t            end;    /* end of the allocated rtext */
        int                     error;
        xfs_rtxnum_t            postblock = 0; /* first rtext allocated > end */
        xfs_rtxnum_t            preblock = 0; /* first rtext allocated < start */

        end = start + len - 1;
        /*
         * Assume we're allocating out of the middle of a free extent.
         * We need to find the beginning and end of the extent so we can
         * properly update the summary.
         */
        error = xfs_rtfind_back(args, start, &preblock);
        if (error)
                return error;

        /*
         * Find the next allocated block (end of free extent).
         */
        error = xfs_rtfind_forw(args, end, args->rtg->rtg_extents - 1,
                        &postblock);
        if (error)
                return error;

        /*
         * Decrement the summary information corresponding to the entire
         * (old) free extent.
         */
        error = xfs_rtmodify_summary(args,
                        xfs_highbit64(postblock + 1 - preblock),
                        xfs_rtx_to_rbmblock(mp, preblock), -1);
        if (error)
                return error;

        /*
         * If there are blocks not being allocated at the front of the
         * old extent, add summary data for them to be free.
         */
        if (preblock < start) {
                error = xfs_rtmodify_summary(args,
                                xfs_highbit64(start - preblock),
                                xfs_rtx_to_rbmblock(mp, preblock), 1);
                if (error)
                        return error;
        }

        /*
         * If there are blocks not being allocated at the end of the
         * old extent, add summary data for them to be free.
         */
        if (postblock > end) {
                error = xfs_rtmodify_summary(args,
                                xfs_highbit64(postblock - end),
                                xfs_rtx_to_rbmblock(mp, end + 1), 1);
                if (error)
                        return error;
        }

        /*
         * Modify the bitmap to mark this extent allocated.
         */
        return xfs_rtmodify_range(args, start, len, 0);
}

/* Reduce @rtxlen until it is a multiple of @prod. */
static inline xfs_rtxlen_t
xfs_rtalloc_align_len(
        xfs_rtxlen_t    rtxlen,
        xfs_rtxlen_t    prod)
{
        if (unlikely(prod > 1))
                return rounddown(rtxlen, prod);
        return rtxlen;
}

/*
 * Make sure we don't run off the end of the rt volume.  Be careful that
 * adjusting maxlen downwards doesn't cause us to fail the alignment checks.
 */
static inline xfs_rtxlen_t
xfs_rtallocate_clamp_len(
        struct xfs_rtgroup      *rtg,
        xfs_rtxnum_t            startrtx,
        xfs_rtxlen_t            rtxlen,
        xfs_rtxlen_t            prod)
{
        xfs_rtxlen_t            ret;

        ret = min(rtg->rtg_extents, startrtx + rtxlen) - startrtx;
        return xfs_rtalloc_align_len(ret, prod);
}

/*
 * Attempt to allocate an extent minlen<=len<=maxlen starting from
 * bitmap block bbno.  If we don't get maxlen then use prod to trim
 * the length, if given.  Returns error; returns starting block in *rtx.
 * The lengths are all in rtextents.
 */
STATIC int
xfs_rtallocate_extent_block(
        struct xfs_rtalloc_args *args,
        xfs_fileoff_t           bbno,   /* bitmap block number */
        xfs_rtxlen_t            minlen, /* minimum length to allocate */
        xfs_rtxlen_t            maxlen, /* maximum length to allocate */
        xfs_rtxlen_t            *len,   /* out: actual length allocated */
        xfs_rtxnum_t            *nextp, /* out: next rtext to try */
        xfs_rtxlen_t            prod,   /* extent product factor */
        xfs_rtxnum_t            *rtx)   /* out: start rtext allocated */
{
        struct xfs_mount        *mp = args->mp;
        xfs_rtxnum_t            besti = -1; /* best rtext found so far */
        xfs_rtxnum_t            end;    /* last rtext in chunk */
        xfs_rtxnum_t            i;      /* current rtext trying */
        xfs_rtxnum_t            next;   /* next rtext to try */
        xfs_rtxlen_t            scanlen; /* number of free rtx to look for */
        xfs_rtxlen_t            bestlen = 0; /* best length found so far */
        int                     stat;   /* status from internal calls */
        int                     error;

        /*
         * Loop over all the extents starting in this bitmap block up to the
         * end of the rt volume, looking for one that's long enough.
         */
        end = min(args->rtg->rtg_extents, xfs_rbmblock_to_rtx(mp, bbno + 1)) -
                1;
        for (i = xfs_rbmblock_to_rtx(mp, bbno); i <= end; i++) {
                /* Make sure we don't scan off the end of the rt volume. */
                scanlen = xfs_rtallocate_clamp_len(args->rtg, i, maxlen, prod);
                if (scanlen < minlen)
                        break;

                /*
                 * See if there's a free extent of scanlen starting at i.
                 * If it's not so then next will contain the first non-free.
                 */
                error = xfs_rtcheck_range(args, i, scanlen, 1, &next, &stat);
                if (error)
                        return error;
                if (stat) {
                        /*
                         * i to scanlen is all free, allocate and return that.
                         */
                        *len = scanlen;
                        *rtx = i;
                        return 0;
                }

                /*
                 * In the case where we have a variable-sized allocation
                 * request, figure out how big this free piece is,
                 * and if it's big enough for the minimum, and the best
                 * so far, remember it.
                 */
                if (minlen < maxlen) {
                        xfs_rtxnum_t    thislen;        /* this extent size */

                        thislen = next - i;
                        if (thislen >= minlen && thislen > bestlen) {
                                besti = i;
                                bestlen = thislen;
                        }
                }
                /*
                 * If not done yet, find the start of the next free space.
                 */
                if (next >= end)
                        break;
                error = xfs_rtfind_forw(args, next, end, &i);
                if (error)
                        return error;
        }

        /* Searched the whole thing & didn't find a maxlen free extent. */
        if (besti == -1)
                goto nospace;

        /*
         * Ensure bestlen is a multiple of prod, but don't return a too-short
         * extent.
         */
        bestlen = xfs_rtalloc_align_len(bestlen, prod);
        if (bestlen < minlen)
                goto nospace;

        /*
         * Pick besti for bestlen & return that.
         */
        *len = bestlen;
        *rtx = besti;
        return 0;
nospace:
        /* Allocation failed.  Set *nextp to the next block to try. */
        *nextp = next;
        return -ENOSPC;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, starting at block
 * bno.  If we don't get maxlen then use prod to trim the length, if given.
 * Returns error; returns starting block in *rtx.
 * The lengths are all in rtextents.
 */
STATIC int
xfs_rtallocate_extent_exact(
        struct xfs_rtalloc_args *args,
        xfs_rtxnum_t            start,  /* starting rtext number to allocate */
        xfs_rtxlen_t            minlen, /* minimum length to allocate */
        xfs_rtxlen_t            maxlen, /* maximum length to allocate */
        xfs_rtxlen_t            *len,   /* out: actual length allocated */
        xfs_rtxlen_t            prod,   /* extent product factor */
        xfs_rtxnum_t            *rtx)   /* out: start rtext allocated */
{
        xfs_rtxnum_t            next;   /* next rtext to try (dummy) */
        xfs_rtxlen_t            alloclen; /* candidate length */
        xfs_rtxlen_t            scanlen; /* number of free rtx to look for */
        int                     isfree; /* extent is free */
        int                     error;

        ASSERT(minlen % prod == 0);
        ASSERT(maxlen % prod == 0);

        /* Make sure we don't run off the end of the rt volume. */
        scanlen = xfs_rtallocate_clamp_len(args->rtg, start, maxlen, prod);
        if (scanlen < minlen)
                return -ENOSPC;

        /* Check if the range in question (for scanlen) is free. */
        error = xfs_rtcheck_range(args, start, scanlen, 1, &next, &isfree);
        if (error)
                return error;

        if (isfree) {
                /* start to scanlen is all free; allocate it. */
                *len = scanlen;
                *rtx = start;
                return 0;
        }

        /*
         * If not, allocate what there is, if it's at least minlen.
         */
        alloclen = next - start;
        if (alloclen < minlen)
                return -ENOSPC;

        /* Ensure alloclen is a multiple of prod. */
        alloclen = xfs_rtalloc_align_len(alloclen, prod);
        if (alloclen < minlen)
                return -ENOSPC;

        *len = alloclen;
        *rtx = start;
        return 0;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, starting as near
 * to start as possible.  If we don't get maxlen then use prod to trim
 * the length, if given.  The lengths are all in rtextents.
 */
STATIC int
xfs_rtallocate_extent_near(
        struct xfs_rtalloc_args *args,
        xfs_rtxnum_t            start,  /* starting rtext number to allocate */
        xfs_rtxlen_t            minlen, /* minimum length to allocate */
        xfs_rtxlen_t            maxlen, /* maximum length to allocate */
        xfs_rtxlen_t            *len,   /* out: actual length allocated */
        xfs_rtxlen_t            prod,   /* extent product factor */
        xfs_rtxnum_t            *rtx)   /* out: start rtext allocated */
{
        struct xfs_mount        *mp = args->mp;
        int                     maxlog; /* max useful extent from summary */
        xfs_fileoff_t           bbno;   /* bitmap block number */
        int                     error;
        int                     i;      /* bitmap block offset (loop control) */
        int                     j;      /* secondary loop control */
        int                     log2len; /* log2 of minlen */
        xfs_rtxnum_t            n;      /* next rtext to try */

        ASSERT(minlen % prod == 0);
        ASSERT(maxlen % prod == 0);

        /*
         * If the block number given is off the end, silently set it to the last
         * block.
         */
        start = min(start, args->rtg->rtg_extents - 1);

        /*
         * Try the exact allocation first.
         */
        error = xfs_rtallocate_extent_exact(args, start, minlen, maxlen, len,
                        prod, rtx);
        if (error != -ENOSPC)
                return error;

        bbno = xfs_rtx_to_rbmblock(mp, start);
        i = 0;
        j = -1;
        ASSERT(minlen != 0);
        log2len = xfs_highbit32(minlen);
        /*
         * Loop over all bitmap blocks (bbno + i is current block).
         */
        for (;;) {
                /*
                 * Get summary information of extents of all useful levels
                 * starting in this bitmap block.
                 */
                error = xfs_rtany_summary(args, log2len, mp->m_rsumlevels - 1,
                                bbno + i, &maxlog);
                if (error)
                        return error;

                /*
                 * If there are any useful extents starting here, try
                 * allocating one.
                 */
                if (maxlog >= 0) {
                        xfs_extlen_t maxavail =
                                min_t(xfs_rtblock_t, maxlen,
                                      (1ULL << (maxlog + 1)) - 1);
                        /*
                         * On the positive side of the starting location.
                         */
                        if (i >= 0) {
                                /*
                                 * Try to allocate an extent starting in
                                 * this block.
                                 */
                                error = xfs_rtallocate_extent_block(args,
                                                bbno + i, minlen, maxavail, len,
                                                &n, prod, rtx);
                                if (error != -ENOSPC)
                                        return error;
                        }
                        /*
                         * On the negative side of the starting location.
                         */
                        else {          /* i < 0 */
                                int     maxblocks;

                                /*
                                 * Loop backwards to find the end of the extent
                                 * we found in the realtime summary.
                                 *
                                 * maxblocks is the maximum possible number of
                                 * bitmap blocks from the start of the extent
                                 * to the end of the extent.
                                 */
                                if (maxlog == 0)
                                        maxblocks = 0;
                                else if (maxlog < mp->m_blkbit_log)
                                        maxblocks = 1;
                                else
                                        maxblocks = 2 << (maxlog - mp->m_blkbit_log);

                                /*
                                 * We need to check bbno + i + maxblocks down to
                                 * bbno + i. We already checked bbno down to
                                 * bbno + j + 1, so we don't need to check those
                                 * again.
                                 */
                                j = min(i + maxblocks, j);
                                for (; j >= i; j--) {
                                        error = xfs_rtallocate_extent_block(args,
                                                        bbno + j, minlen,
                                                        maxavail, len, &n, prod,
                                                        rtx);
                                        if (error != -ENOSPC)
                                                return error;
                                }
                        }
                }
                /*
                 * Loop control.  If we were on the positive side, and there's
                 * still more blocks on the negative side, go there.
                 */
                if (i > 0 && (int)bbno - i >= 0)
                        i = -i;
                /*
                 * If positive, and no more negative, but there are more
                 * positive, go there.
                 */
                else if (i > 0 && (int)bbno + i < mp->m_sb.sb_rbmblocks - 1)
                        i++;
                /*
                 * If negative or 0 (just started), and there are positive
                 * blocks to go, go there.  The 0 case moves to block 1.
                 */
                else if (i <= 0 && (int)bbno - i < mp->m_sb.sb_rbmblocks - 1)
                        i = 1 - i;
                /*
                 * If negative or 0 and there are more negative blocks,
                 * go there.
                 */
                else if (i <= 0 && (int)bbno + i > 0)
                        i--;
                /*
                 * Must be done.  Return failure.
                 */
                else
                        break;
        }
        return -ENOSPC;
}

static int
xfs_rtalloc_sumlevel(
        struct xfs_rtalloc_args *args,
        int                     l,      /* level number */
        xfs_rtxlen_t            minlen, /* minimum length to allocate */
        xfs_rtxlen_t            maxlen, /* maximum length to allocate */
        xfs_rtxlen_t            prod,   /* extent product factor */
        xfs_rtxlen_t            *len,   /* out: actual length allocated */
        xfs_rtxnum_t            *rtx)   /* out: start rtext allocated */
{
        xfs_fileoff_t           i;      /* bitmap block number */
        int                     error;

        for (i = 0; i < args->mp->m_sb.sb_rbmblocks; i++) {
                xfs_suminfo_t   sum;    /* summary information for extents */
                xfs_rtxnum_t    n;      /* next rtext to be tried */

                error = xfs_rtget_summary(args, l, i, &sum);
                if (error)
                        return error;

                /*
                 * Nothing there, on to the next block.
                 */
                if (!sum)
                        continue;

                /*
                 * Try allocating the extent.
                 */
                error = xfs_rtallocate_extent_block(args, i, minlen, maxlen,
                                len, &n, prod, rtx);
                if (error != -ENOSPC)
                        return error;

                /*
                 * If the "next block to try" returned from the allocator is
                 * beyond the next bitmap block, skip to that bitmap block.
                 */
                if (xfs_rtx_to_rbmblock(args->mp, n) > i + 1)
                        i = xfs_rtx_to_rbmblock(args->mp, n) - 1;
        }

        return -ENOSPC;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, with no position
 * specified.  If we don't get maxlen then use prod to trim
 * the length, if given.  The lengths are all in rtextents.
 */
static int
xfs_rtallocate_extent_size(
        struct xfs_rtalloc_args *args,
        xfs_rtxlen_t            minlen, /* minimum length to allocate */
        xfs_rtxlen_t            maxlen, /* maximum length to allocate */
        xfs_rtxlen_t            *len,   /* out: actual length allocated */
        xfs_rtxlen_t            prod,   /* extent product factor */
        xfs_rtxnum_t            *rtx)   /* out: start rtext allocated */
{
        int                     error;
        int                     l;      /* level number (loop control) */

        ASSERT(minlen % prod == 0);
        ASSERT(maxlen % prod == 0);
        ASSERT(maxlen != 0);

        /*
         * Loop over all the levels starting with maxlen.
         *
         * At each level, look at all the bitmap blocks, to see if there are
         * extents starting there that are long enough (>= maxlen).
         *
         * Note, only on the initial level can the allocation fail if the
         * summary says there's an extent.
         */
        for (l = xfs_highbit32(maxlen); l < args->mp->m_rsumlevels; l++) {
                error = xfs_rtalloc_sumlevel(args, l, minlen, maxlen, prod, len,
                                rtx);
                if (error != -ENOSPC)
                        return error;
        }

        /*
         * Didn't find any maxlen blocks.  Try smaller ones, unless we are
         * looking for a fixed size extent.
         */
        if (minlen > --maxlen)
                return -ENOSPC;
        ASSERT(minlen != 0);
        ASSERT(maxlen != 0);

        /*
         * Loop over sizes, from maxlen down to minlen.
         *
         * This time, when we do the allocations, allow smaller ones to succeed,
         * but make sure the specified minlen/maxlen are in the possible range
         * for this summary level.
         */
        for (l = xfs_highbit32(maxlen); l >= xfs_highbit32(minlen); l--) {
                error = xfs_rtalloc_sumlevel(args, l,
                                max_t(xfs_rtxlen_t, minlen, 1 << l),
                                min_t(xfs_rtxlen_t, maxlen, (1 << (l + 1)) - 1),
                                prod, len, rtx);
                if (error != -ENOSPC)
                        return error;
        }

        return -ENOSPC;
}

static void
xfs_rtunmount_rtg(
        struct xfs_rtgroup      *rtg)
{
        int                     i;

        for (i = 0; i < XFS_RTGI_MAX; i++)
                xfs_rtginode_irele(&rtg->rtg_inodes[i]);
        if (!xfs_has_zoned(rtg_mount(rtg)))
                kvfree(rtg->rtg_rsum_cache);
}

static int
xfs_alloc_rsum_cache(
        struct xfs_rtgroup      *rtg,
        xfs_extlen_t            rbmblocks)
{
        /*
         * The rsum cache is initialized to the maximum value, which is
         * trivially an upper bound on the maximum level with any free extents.
         */
        rtg->rtg_rsum_cache = kvmalloc(rbmblocks, GFP_KERNEL);
        if (!rtg->rtg_rsum_cache)
                return -ENOMEM;
        memset(rtg->rtg_rsum_cache, -1, rbmblocks);
        return 0;
}

/*
 * If we changed the rt extent size (meaning there was no rt volume previously)
 * and the root directory had EXTSZINHERIT and RTINHERIT set, it's possible
 * that the extent size hint on the root directory is no longer congruent with
 * the new rt extent size.  Log the rootdir inode to fix this.
 */
static int
xfs_growfs_rt_fixup_extsize(
        struct xfs_mount        *mp)
{
        struct xfs_inode        *ip = mp->m_rootip;
        struct xfs_trans        *tp;
        int                     error = 0;

        xfs_ilock(ip, XFS_IOLOCK_EXCL);
        if (!(ip->i_diflags & XFS_DIFLAG_RTINHERIT) ||
            !(ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT))
                goto out_iolock;

        error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_ichange, 0, 0, false,
                        &tp);
        if (error)
                goto out_iolock;

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        error = xfs_trans_commit(tp);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);

out_iolock:
        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
        return error;
}

/* Ensure that the rtgroup metadata inode is loaded, creating it if neeeded. */
static int
xfs_rtginode_ensure(
        struct xfs_rtgroup      *rtg,
        enum xfs_rtg_inodes     type)
{
        struct xfs_trans        *tp;
        int                     error;

        if (rtg->rtg_inodes[type])
                return 0;

        tp = xfs_trans_alloc_empty(rtg_mount(rtg));
        error = xfs_rtginode_load(rtg, type, tp);
        xfs_trans_cancel(tp);

        if (error != -ENOENT)
                return 0;
        return xfs_rtginode_create(rtg, type, true);
}

static struct xfs_mount *
xfs_growfs_rt_alloc_fake_mount(
        const struct xfs_mount  *mp,
        xfs_rfsblock_t          rblocks,
        xfs_agblock_t           rextsize)
{
        struct xfs_mount        *nmp;

        nmp = kmemdup(mp, sizeof(*mp), GFP_KERNEL);
        if (!nmp)
                return NULL;
        xfs_mount_sb_set_rextsize(nmp, &nmp->m_sb, rextsize);
        nmp->m_sb.sb_rblocks = rblocks;
        nmp->m_sb.sb_rextents = xfs_blen_to_rtbxlen(nmp, nmp->m_sb.sb_rblocks);
        nmp->m_sb.sb_rbmblocks = xfs_rtbitmap_blockcount(nmp);
        nmp->m_sb.sb_rextslog = xfs_compute_rextslog(nmp->m_sb.sb_rextents);
        if (xfs_has_rtgroups(nmp))
                nmp->m_sb.sb_rgcount = howmany_64(nmp->m_sb.sb_rextents,
                                                  nmp->m_sb.sb_rgextents);
        else
                nmp->m_sb.sb_rgcount = 1;
        nmp->m_rsumblocks = xfs_rtsummary_blockcount(nmp, &nmp->m_rsumlevels);

        if (rblocks > 0)
                nmp->m_features |= XFS_FEAT_REALTIME;

        /* recompute growfsrt reservation from new rsumsize */
        xfs_trans_resv_calc(nmp, &nmp->m_resv);
        return nmp;
}

/* Free all the new space and return the number of extents actually freed. */
static int
xfs_growfs_rt_free_new(
        struct xfs_rtgroup      *rtg,
        struct xfs_rtalloc_args *nargs,
        xfs_rtbxlen_t           *freed_rtx)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        xfs_rgnumber_t          rgno = rtg_rgno(rtg);
        xfs_rtxnum_t            start_rtx = 0, end_rtx;

        if (rgno < mp->m_sb.sb_rgcount)
                start_rtx = xfs_rtgroup_extents(mp, rgno);
        end_rtx = xfs_rtgroup_extents(nargs->mp, rgno);

        /*
         * Compute the first new extent that we want to free, being careful to
         * skip past a realtime superblock at the start of the realtime volume.
         */
        if (xfs_has_rtsb(nargs->mp) && rgno == 0 && start_rtx == 0)
                start_rtx++;
        *freed_rtx = end_rtx - start_rtx;
        return xfs_rtfree_range(nargs, start_rtx, *freed_rtx);
}

static xfs_rfsblock_t
xfs_growfs_rt_nrblocks(
        struct xfs_rtgroup      *rtg,
        xfs_rfsblock_t          nrblocks,
        xfs_agblock_t           rextsize,
        xfs_fileoff_t           bmbno)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        xfs_rfsblock_t          step;

        step = (bmbno + 1) * mp->m_rtx_per_rbmblock * rextsize;
        if (xfs_has_rtgroups(mp)) {
                xfs_rfsblock_t  rgblocks = mp->m_sb.sb_rgextents * rextsize;

                step = min(rgblocks, step) + rgblocks * rtg_rgno(rtg);
        }

        return min(nrblocks, step);
}

/*
 * If the post-grow filesystem will have an rtsb; we're initializing the first
 * rtgroup; and the filesystem didn't have a realtime section, write the rtsb
 * now, and attach the rtsb buffer to the real mount.
 */
static int
xfs_growfs_rt_init_rtsb(
        const struct xfs_rtalloc_args   *nargs,
        const struct xfs_rtgroup        *rtg,
        const struct xfs_rtalloc_args   *args)
{
        struct xfs_mount                *mp = args->mp;
        struct xfs_buf                  *rtsb_bp;
        int                             error;

        if (!xfs_has_rtsb(nargs->mp))
                return 0;
        if (rtg_rgno(rtg) > 0)
                return 0;
        if (mp->m_sb.sb_rblocks)
                return 0;

        error = xfs_buf_get_uncached(mp->m_rtdev_targp, XFS_FSB_TO_BB(mp, 1),
                        &rtsb_bp);
        if (error)
                return error;

        rtsb_bp->b_maps[0].bm_bn = XFS_RTSB_DADDR;
        rtsb_bp->b_ops = &xfs_rtsb_buf_ops;

        xfs_update_rtsb(rtsb_bp, mp->m_sb_bp);
        mp->m_rtsb_bp = rtsb_bp;
        error = xfs_bwrite(rtsb_bp);
        xfs_buf_unlock(rtsb_bp);
        if (error)
                return error;

        /* Initialize the rtrmap to reflect the rtsb. */
        if (rtg_rmap(args->rtg) != NULL)
                error = xfs_rtrmapbt_init_rtsb(nargs->mp, args->rtg, args->tp);

        return error;
}

static void
xfs_growfs_rt_sb_fields(
        struct xfs_trans        *tp,
        const struct xfs_mount  *nmp)
{
        struct xfs_mount        *mp = tp->t_mountp;

        if (nmp->m_sb.sb_rextsize != mp->m_sb.sb_rextsize)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSIZE,
                        nmp->m_sb.sb_rextsize - mp->m_sb.sb_rextsize);
        if (nmp->m_sb.sb_rbmblocks != mp->m_sb.sb_rbmblocks)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBMBLOCKS,
                        nmp->m_sb.sb_rbmblocks - mp->m_sb.sb_rbmblocks);
        if (nmp->m_sb.sb_rblocks != mp->m_sb.sb_rblocks)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBLOCKS,
                        nmp->m_sb.sb_rblocks - mp->m_sb.sb_rblocks);
        if (nmp->m_sb.sb_rextents != mp->m_sb.sb_rextents)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTENTS,
                        nmp->m_sb.sb_rextents - mp->m_sb.sb_rextents);
        if (nmp->m_sb.sb_rextslog != mp->m_sb.sb_rextslog)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSLOG,
                        nmp->m_sb.sb_rextslog - mp->m_sb.sb_rextslog);
        if (nmp->m_sb.sb_rgcount != mp->m_sb.sb_rgcount)
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_RGCOUNT,
                        nmp->m_sb.sb_rgcount - mp->m_sb.sb_rgcount);
}

static int
xfs_growfs_rt_zoned(
        struct xfs_rtgroup      *rtg,
        xfs_rfsblock_t          nrblocks)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_mount        *nmp;
        struct xfs_trans        *tp;
        xfs_rtbxlen_t           freed_rtx;
        int                     error;

        /*
         * Calculate new sb and mount fields for this round.  Also ensure the
         * rtg_extents value is uptodate as the rtbitmap code relies on it.
         */
        nmp = xfs_growfs_rt_alloc_fake_mount(mp, nrblocks,
                        mp->m_sb.sb_rextsize);
        if (!nmp)
                return -ENOMEM;
        freed_rtx = nmp->m_sb.sb_rextents - mp->m_sb.sb_rextents;

        xfs_rtgroup_calc_geometry(nmp, rtg, rtg_rgno(rtg),
                        nmp->m_sb.sb_rgcount, nmp->m_sb.sb_rextents);

        error = xfs_trans_alloc(mp, &M_RES(nmp)->tr_growrtfree, 0, 0, 0, &tp);
        if (error)
                goto out_free;

        xfs_rtgroup_lock(rtg, XFS_RTGLOCK_RMAP);
        xfs_rtgroup_trans_join(tp, rtg, XFS_RTGLOCK_RMAP);

        xfs_growfs_rt_sb_fields(tp, nmp);
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, freed_rtx);

        error = xfs_trans_commit(tp);
        if (error)
                goto out_free;

        /*
         * Ensure the mount RT feature flag is now set, and compute new
         * maxlevels for rt btrees.
         */
        mp->m_features |= XFS_FEAT_REALTIME;
        xfs_rtrmapbt_compute_maxlevels(mp);
        xfs_rtrefcountbt_compute_maxlevels(mp);
        xfs_zoned_add_available(mp, freed_rtx);
out_free:
        kfree(nmp);
        return error;
}

static int
xfs_growfs_rt_bmblock(
        struct xfs_rtgroup      *rtg,
        xfs_rfsblock_t          nrblocks,
        xfs_agblock_t           rextsize,
        xfs_fileoff_t           bmbno)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_inode        *rbmip = rtg_bitmap(rtg);
        struct xfs_inode        *rsumip = rtg_summary(rtg);
        struct xfs_rtalloc_args args = {
                .mp             = mp,
                .rtg            = rtg,
        };
        struct xfs_rtalloc_args nargs = {
                .rtg            = rtg,
        };
        struct xfs_mount        *nmp;
        xfs_rtbxlen_t           freed_rtx;
        int                     error;

        /*
         * Calculate new sb and mount fields for this round.  Also ensure the
         * rtg_extents value is uptodate as the rtbitmap code relies on it.
         */
        nmp = nargs.mp = xfs_growfs_rt_alloc_fake_mount(mp,
                        xfs_growfs_rt_nrblocks(rtg, nrblocks, rextsize, bmbno),
                        rextsize);
        if (!nmp)
                return -ENOMEM;

        xfs_rtgroup_calc_geometry(nmp, rtg, rtg_rgno(rtg),
                        nmp->m_sb.sb_rgcount, nmp->m_sb.sb_rextents);

        /*
         * Recompute the growfsrt reservation from the new rsumsize, so that the
         * transaction below use the new, potentially larger value.
         * */
        xfs_trans_resv_calc(nmp, &nmp->m_resv);
        error = xfs_trans_alloc(mp, &M_RES(nmp)->tr_growrtfree, 0, 0, 0,
                        &args.tp);
        if (error)
                goto out_free;
        nargs.tp = args.tp;

        xfs_rtgroup_lock(args.rtg, XFS_RTGLOCK_BITMAP | XFS_RTGLOCK_RMAP);
        xfs_rtgroup_trans_join(args.tp, args.rtg,
                        XFS_RTGLOCK_BITMAP | XFS_RTGLOCK_RMAP);

        /*
         * Update the bitmap inode's size ondisk and incore.  We need to update
         * the incore size so that inode inactivation won't punch what it thinks
         * are "posteof" blocks.
         */
        rbmip->i_disk_size = nmp->m_sb.sb_rbmblocks * nmp->m_sb.sb_blocksize;
        i_size_write(VFS_I(rbmip), rbmip->i_disk_size);
        xfs_trans_log_inode(args.tp, rbmip, XFS_ILOG_CORE);

        /*
         * Update the summary inode's size.  We need to update the incore size
         * so that inode inactivation won't punch what it thinks are "posteof"
         * blocks.
         */
        rsumip->i_disk_size = nmp->m_rsumblocks * nmp->m_sb.sb_blocksize;
        i_size_write(VFS_I(rsumip), rsumip->i_disk_size);
        xfs_trans_log_inode(args.tp, rsumip, XFS_ILOG_CORE);

        /*
         * Copy summary data from old to new sizes when the real size (not
         * block-aligned) changes.
         */
        if (mp->m_sb.sb_rbmblocks != nmp->m_sb.sb_rbmblocks ||
            mp->m_rsumlevels != nmp->m_rsumlevels) {
                error = xfs_rtcopy_summary(&args, &nargs);
                if (error)
                        goto out_cancel;
        }

        error = xfs_growfs_rt_init_rtsb(&nargs, rtg, &args);
        if (error)
                goto out_cancel;

        /*
         * Update superblock fields.
         */
        xfs_growfs_rt_sb_fields(args.tp, nmp);

        /*
         * Free the new extent.
         */
        error = xfs_growfs_rt_free_new(rtg, &nargs, &freed_rtx);
        xfs_rtbuf_cache_relse(&nargs);
        if (error)
                goto out_cancel;

        /*
         * Mark more blocks free in the superblock.
         */
        xfs_trans_mod_sb(args.tp, XFS_TRANS_SB_FREXTENTS, freed_rtx);

        /*
         * Update the calculated values in the real mount structure.
         */
        mp->m_rsumlevels = nmp->m_rsumlevels;
        mp->m_rsumblocks = nmp->m_rsumblocks;

        /*
         * Recompute the growfsrt reservation from the new rsumsize.
         */
        xfs_trans_resv_calc(mp, &mp->m_resv);

        /*
         * Sync sb counters now to reflect the updated values. Lazy counters are
         * not always updated and in order to avoid inconsistencies between
         * frextents and rtextents, it is better to sync the counters.
         */

        if (xfs_has_lazysbcount(mp))
                xfs_log_sb(args.tp);

        error = xfs_trans_commit(args.tp);
        if (error)
                goto out_free;

        /*
         * Ensure the mount RT feature flag is now set, and compute new
         * maxlevels for rt btrees.
         */
        mp->m_features |= XFS_FEAT_REALTIME;
        xfs_rtrmapbt_compute_maxlevels(mp);
        xfs_rtrefcountbt_compute_maxlevels(mp);

        kfree(nmp);
        return 0;

out_cancel:
        xfs_trans_cancel(args.tp);
out_free:
        kfree(nmp);
        return error;
}

static xfs_rtxnum_t
xfs_last_rtgroup_extents(
        struct xfs_mount        *mp)
{
        return mp->m_sb.sb_rextents -
                ((xfs_rtxnum_t)(mp->m_sb.sb_rgcount - 1) *
                 mp->m_sb.sb_rgextents);
}

/*
 * This will return the bitmap block number (indexed at 0) that will be
 * extended/modified. There are 2 cases here:
 * 1. The size of the rtg is such that it is a multiple of
 *    xfs_rtbitmap_rtx_per_rbmblock() i.e, an integral number of bitmap blocks
 *    are completely filled up. In this case, we should return
 *    1 + (the last used bitmap block number).
 * 2. The size of the rtg is not an multiple of xfs_rtbitmap_rtx_per_rbmblock().
 *    Here we will return the block number of last used block number. In this
 *    case, we will modify the last used bitmap block to extend the size of the
 *    rtgroup.
 *
 * This also deals with the case where there were no rtextents before.
 */
static xfs_fileoff_t
xfs_last_rt_bmblock_to_extend(
        struct xfs_rtgroup      *rtg)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        xfs_rgnumber_t          rgno = rtg_rgno(rtg);
        xfs_fileoff_t           bmbno = 0;
        unsigned int            mod = 0;

        ASSERT(!mp->m_sb.sb_rgcount || rgno >= mp->m_sb.sb_rgcount - 1);

        if (mp->m_sb.sb_rgcount && rgno == mp->m_sb.sb_rgcount - 1) {
                xfs_rtxnum_t    nrext = xfs_last_rtgroup_extents(mp);

                /* Also fill up the previous block if not entirely full. */
                /* We are doing a -1 to convert it to a 0 based index */
                bmbno = xfs_rtbitmap_blockcount_len(mp, nrext) - 1;
                div_u64_rem(nrext, xfs_rtbitmap_rtx_per_rbmblock(mp), &mod);
                /*
                 * mod = 0 means that all the current blocks are full. So
                 * return the next block number to be used for the rtgroup
                 * growth.
                 */
                if (mod == 0)
                        bmbno++;
        }

        return bmbno;
}

/*
 * Allocate space to the bitmap and summary files, as necessary.
 */
static int
xfs_growfs_rt_alloc_blocks(
        struct xfs_rtgroup      *rtg,
        xfs_rfsblock_t          nrblocks,
        xfs_agblock_t           rextsize,
        xfs_extlen_t            *nrbmblocks)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_inode        *rbmip = rtg_bitmap(rtg);
        struct xfs_inode        *rsumip = rtg_summary(rtg);
        xfs_extlen_t            orbmblocks = 0;
        xfs_extlen_t            orsumblocks = 0;
        struct xfs_mount        *nmp;
        int                     error = 0;

        nmp = xfs_growfs_rt_alloc_fake_mount(mp, nrblocks, rextsize);
        if (!nmp)
                return -ENOMEM;
        *nrbmblocks = nmp->m_sb.sb_rbmblocks;

        if (xfs_has_rtgroups(mp)) {
                /*
                 * For file systems with the rtgroups feature, the RT bitmap and
                 * summary are always fully allocated, which means that we never
                 * need to grow the existing files.
                 *
                 * But we have to be careful to only fill the bitmap until the
                 * end of the actually used range.
                 */
                if (rtg_rgno(rtg) == nmp->m_sb.sb_rgcount - 1)
                        *nrbmblocks = xfs_rtbitmap_blockcount_len(nmp,
                                        xfs_last_rtgroup_extents(nmp));

                if (mp->m_sb.sb_rgcount &&
                    rtg_rgno(rtg) == mp->m_sb.sb_rgcount - 1)
                        goto out_free;
        } else {
                /*
                 * Get the old block counts for bitmap and summary inodes.
                 * These can't change since other growfs callers are locked out.
                 */
                orbmblocks = XFS_B_TO_FSB(mp, rbmip->i_disk_size);
                orsumblocks = XFS_B_TO_FSB(mp, rsumip->i_disk_size);
        }

        error = xfs_rtfile_initialize_blocks(rtg, XFS_RTGI_BITMAP, orbmblocks,
                        nmp->m_sb.sb_rbmblocks, NULL);
        if (error)
                goto out_free;
        error = xfs_rtfile_initialize_blocks(rtg, XFS_RTGI_SUMMARY, orsumblocks,
                        nmp->m_rsumblocks, NULL);
out_free:
        kfree(nmp);
        return error;
}

static int
xfs_growfs_rtg(
        struct xfs_mount        *mp,
        xfs_rgnumber_t          rgno,
        xfs_rfsblock_t          nrblocks,
        xfs_agblock_t           rextsize)
{
        uint8_t                 *old_rsum_cache = NULL;
        xfs_extlen_t            bmblocks;
        xfs_fileoff_t           bmbno;
        struct xfs_rtgroup      *rtg;
        unsigned int            i;
        int                     error;

        rtg = xfs_rtgroup_grab(mp, rgno);
        if (!rtg)
                return -EINVAL;

        for (i = 0; i < XFS_RTGI_MAX; i++) {
                error = xfs_rtginode_ensure(rtg, i);
                if (error)
                        goto out_rele;
        }

        if (xfs_has_zoned(mp)) {
                error = xfs_growfs_rt_zoned(rtg, nrblocks);
                goto out_rele;
        }

        error = xfs_growfs_rt_alloc_blocks(rtg, nrblocks, rextsize, &bmblocks);
        if (error)
                goto out_rele;

        if (bmblocks != rtg_mount(rtg)->m_sb.sb_rbmblocks) {
                old_rsum_cache = rtg->rtg_rsum_cache;
                error = xfs_alloc_rsum_cache(rtg, bmblocks);
                if (error)
                        goto out_rele;
        }

        for (bmbno = xfs_last_rt_bmblock_to_extend(rtg); bmbno < bmblocks;
                        bmbno++) {
                error = xfs_growfs_rt_bmblock(rtg, nrblocks, rextsize, bmbno);
                if (error)
                        goto out_error;
        }

        kvfree(old_rsum_cache);
        goto out_rele;

out_error:
        /*
         * Reset rtg_extents to the old value if adding more blocks failed.
         */
        xfs_rtgroup_calc_geometry(mp, rtg, rtg_rgno(rtg), mp->m_sb.sb_rgcount,
                        mp->m_sb.sb_rextents);
        if (old_rsum_cache) {
                kvfree(rtg->rtg_rsum_cache);
                rtg->rtg_rsum_cache = old_rsum_cache;
        }
out_rele:
        xfs_rtgroup_rele(rtg);
        return error;
}

int
xfs_growfs_check_rtgeom(
        const struct xfs_mount  *mp,
        xfs_rfsblock_t          dblocks,
        xfs_rfsblock_t          rblocks,
        xfs_extlen_t            rextsize)
{
        xfs_extlen_t            min_logfsbs;
        struct xfs_mount        *nmp;

        nmp = xfs_growfs_rt_alloc_fake_mount(mp, rblocks, rextsize);
        if (!nmp)
                return -ENOMEM;
        nmp->m_sb.sb_dblocks = dblocks;

        xfs_rtrmapbt_compute_maxlevels(nmp);
        xfs_rtrefcountbt_compute_maxlevels(nmp);
        xfs_trans_resv_calc(nmp, M_RES(nmp));

        /*
         * New summary size can't be more than half the size of the log.  This
         * prevents us from getting a log overflow, since we'll log basically
         * the whole summary file at once.
         */
        min_logfsbs = min_t(xfs_extlen_t, xfs_log_calc_minimum_size(nmp),
                        nmp->m_rsumblocks * 2);

        trace_xfs_growfs_check_rtgeom(mp, min_logfsbs);

        if (min_logfsbs > mp->m_sb.sb_logblocks)
                goto out_inval;

        if (xfs_has_zoned(mp)) {
                uint32_t        gblocks = mp->m_groups[XG_TYPE_RTG].blocks;
                uint32_t        rem;

                if (rextsize != 1)
                        goto out_inval;
                div_u64_rem(nmp->m_sb.sb_rblocks, gblocks, &rem);
                if (rem) {
                        xfs_warn(mp,
"new RT volume size (%lld) not aligned to RT group size (%d)",
                                nmp->m_sb.sb_rblocks, gblocks);
                        goto out_inval;
                }
        }

        kfree(nmp);
        return 0;
out_inval:
        kfree(nmp);
        return -EINVAL;
}

/*
 * Compute the new number of rt groups and ensure that /rtgroups exists.
 *
 * Changing the rtgroup size is not allowed (even if the rt volume hasn't yet
 * been initialized) because the userspace ABI doesn't support it.
 */
static int
xfs_growfs_rt_prep_groups(
        struct xfs_mount        *mp,
        xfs_rfsblock_t          rblocks,
        xfs_extlen_t            rextsize,
        xfs_rgnumber_t          *new_rgcount)
{
        int                     error;

        *new_rgcount = howmany_64(rblocks, mp->m_sb.sb_rgextents * rextsize);
        if (*new_rgcount > XFS_MAX_RGNUMBER)
                return -EINVAL;

        /* Make sure the /rtgroups dir has been created */
        if (!mp->m_rtdirip) {
                struct xfs_trans        *tp;

                tp = xfs_trans_alloc_empty(mp);
                error = xfs_rtginode_load_parent(tp);
                xfs_trans_cancel(tp);

                if (error == -ENOENT)
                        error = xfs_rtginode_mkdir_parent(mp);
                if (error)
                        return error;
        }

        return 0;
}

static bool
xfs_grow_last_rtg(
        struct xfs_mount        *mp)
{
        if (!xfs_has_rtgroups(mp))
                return true;
        if (mp->m_sb.sb_rgcount == 0)
                return false;
        return xfs_rtgroup_extents(mp, mp->m_sb.sb_rgcount - 1) <
                        mp->m_sb.sb_rgextents;
}

/*
 * Read in the last block of the RT device to make sure it is accessible.
 */
static int
xfs_rt_check_size(
        struct xfs_mount        *mp,
        xfs_rfsblock_t          last_block)
{
        xfs_daddr_t             daddr = XFS_FSB_TO_BB(mp, last_block);
        struct xfs_buf          *bp;
        int                     error;

        if (XFS_BB_TO_FSB(mp, daddr) != last_block) {
                xfs_warn(mp, "RT device size overflow: %llu != %llu",
                        XFS_BB_TO_FSB(mp, daddr), last_block);
                return -EFBIG;
        }

        error = xfs_buf_read_uncached(mp->m_rtdev_targp,
                        XFS_FSB_TO_BB(mp, mp->m_sb.sb_rtstart) + daddr,
                        XFS_FSB_TO_BB(mp, 1), &bp, NULL);
        if (error)
                xfs_warn(mp, "cannot read last RT device sector (%lld)",
                                last_block);
        else
                xfs_buf_relse(bp);
        return error;
}

/*
 * Grow the realtime area of the filesystem.
 */
int
xfs_growfs_rt(
        struct xfs_mount        *mp,
        struct xfs_growfs_rt    *in)
{
        xfs_rgnumber_t          old_rgcount = mp->m_sb.sb_rgcount;
        xfs_rgnumber_t          new_rgcount = 1;
        xfs_rgnumber_t          rgno;
        xfs_agblock_t           old_rextsize = mp->m_sb.sb_rextsize;
        int                     error;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        /* Needs to have been mounted with an rt device. */
        if (!XFS_IS_REALTIME_MOUNT(mp))
                return -EINVAL;

        if (!mutex_trylock(&mp->m_growlock))
                return -EWOULDBLOCK;

        /* Shrink not supported. */
        error = -EINVAL;
        if (in->newblocks <= mp->m_sb.sb_rblocks)
                goto out_unlock;
        /* Can only change rt extent size when adding rt volume. */
        if (mp->m_sb.sb_rblocks > 0 && in->extsize != mp->m_sb.sb_rextsize)
                goto out_unlock;

        /* Range check the extent size. */
        if (XFS_FSB_TO_B(mp, in->extsize) > XFS_MAX_RTEXTSIZE ||
            XFS_FSB_TO_B(mp, in->extsize) < XFS_MIN_RTEXTSIZE)
                goto out_unlock;

        /* Check for features supported only on rtgroups filesystems. */
        error = -EOPNOTSUPP;
        if (!xfs_has_rtgroups(mp)) {
                if (xfs_has_rmapbt(mp))
                        goto out_unlock;
                if (xfs_has_quota(mp))
                        goto out_unlock;
                if (xfs_has_reflink(mp))
                        goto out_unlock;
        } else if (xfs_has_reflink(mp) &&
                   !xfs_reflink_supports_rextsize(mp, in->extsize))
                goto out_unlock;

        error = xfs_sb_validate_fsb_count(&mp->m_sb, in->newblocks);
        if (error)
                goto out_unlock;

        error = xfs_rt_check_size(mp, in->newblocks - 1);
        if (error)
                goto out_unlock;

        /*
         * Calculate new parameters.  These are the final values to be reached.
         */
        error = -EINVAL;
        if (in->newblocks < in->extsize)
                goto out_unlock;

        /* Make sure the new fs size won't cause problems with the log. */
        error = xfs_growfs_check_rtgeom(mp, mp->m_sb.sb_dblocks, in->newblocks,
                        in->extsize);
        if (error)
                goto out_unlock;

        if (xfs_has_rtgroups(mp)) {
                error = xfs_growfs_rt_prep_groups(mp, in->newblocks,
                                in->extsize, &new_rgcount);
                if (error)
                        goto out_unlock;
        }

        if (xfs_grow_last_rtg(mp)) {
                error = xfs_growfs_rtg(mp, old_rgcount - 1, in->newblocks,
                                in->extsize);
                if (error)
                        goto out_unlock;
        }

        for (rgno = old_rgcount; rgno < new_rgcount; rgno++) {
                xfs_rtbxlen_t   rextents = div_u64(in->newblocks, in->extsize);

                error = xfs_rtgroup_alloc(mp, rgno, new_rgcount, rextents);
                if (error)
                        goto out_unlock;

                error = xfs_growfs_rtg(mp, rgno, in->newblocks, in->extsize);
                if (error) {
                        struct xfs_rtgroup      *rtg;

                        rtg = xfs_rtgroup_grab(mp, rgno);
                        if (!WARN_ON_ONCE(!rtg)) {
                                xfs_rtunmount_rtg(rtg);
                                xfs_rtgroup_rele(rtg);
                                xfs_rtgroup_free(mp, rgno);
                        }
                        break;
                }
        }

        if (!error && old_rextsize != in->extsize)
                error = xfs_growfs_rt_fixup_extsize(mp);

        /*
         * Update secondary superblocks now the physical grow has completed.
         *
         * Also do this in case of an error as we might have already
         * successfully updated one or more RTGs and incremented sb_rgcount.
         */
        if (!xfs_is_shutdown(mp)) {
                int error2 = xfs_update_secondary_sbs(mp);

                if (!error)
                        error = error2;

                /* Reset the rt metadata btree space reservations. */
                error2 = xfs_metafile_resv_init(mp);
                if (error2 && error2 != -ENOSPC)
                        error = error2;
        }

out_unlock:
        mutex_unlock(&mp->m_growlock);
        return error;
}

/* Read the realtime superblock and attach it to the mount. */
int
xfs_rtmount_readsb(
        struct xfs_mount        *mp)
{
        struct xfs_buf          *bp;
        int                     error;

        if (!xfs_has_rtsb(mp))
                return 0;
        if (mp->m_sb.sb_rblocks == 0)
                return 0;
        if (mp->m_rtdev_targp == NULL) {
                xfs_warn(mp,
        "Filesystem has a realtime volume, use rtdev=device option");
                return -ENODEV;
        }

        /* m_blkbb_log is not set up yet */
        error = xfs_buf_read_uncached(mp->m_rtdev_targp, XFS_RTSB_DADDR,
                        mp->m_sb.sb_blocksize >> BBSHIFT, &bp,
                        &xfs_rtsb_buf_ops);
        if (error) {
                xfs_warn(mp, "rt sb validate failed with error %d.", error);
                /* bad CRC means corrupted metadata */
                if (error == -EFSBADCRC)
                        error = -EFSCORRUPTED;
                return error;
        }

        mp->m_rtsb_bp = bp;
        xfs_buf_unlock(bp);
        return 0;
}

/* Detach the realtime superblock from the mount and free it. */
void
xfs_rtmount_freesb(
        struct xfs_mount        *mp)
{
        struct xfs_buf          *bp = mp->m_rtsb_bp;

        if (!bp)
                return;

        xfs_buf_lock(bp);
        mp->m_rtsb_bp = NULL;
        xfs_buf_relse(bp);
}

/*
 * Initialize realtime fields in the mount structure.
 */
int                             /* error */
xfs_rtmount_init(
        struct xfs_mount        *mp)    /* file system mount structure */
{
        if (mp->m_sb.sb_rblocks == 0)
                return 0;
        if (mp->m_rtdev_targp == NULL) {
                xfs_warn(mp,
        "Filesystem has a realtime volume, use rtdev=device option");
                return -ENODEV;
        }

        mp->m_rsumblocks = xfs_rtsummary_blockcount(mp, &mp->m_rsumlevels);

        return xfs_rt_check_size(mp, mp->m_sb.sb_rblocks - 1);
}

static int
xfs_rtalloc_count_frextent(
        struct xfs_rtgroup              *rtg,
        struct xfs_trans                *tp,
        const struct xfs_rtalloc_rec    *rec,
        void                            *priv)
{
        uint64_t                        *valp = priv;

        *valp += rec->ar_extcount;
        return 0;
}

/*
 * Reinitialize the number of free realtime extents from the realtime bitmap.
 * Callers must ensure that there is no other activity in the filesystem.
 */
int
xfs_rtalloc_reinit_frextents(
        struct xfs_mount        *mp)
{
        uint64_t                val = 0;
        int                     error;

        struct xfs_rtgroup      *rtg = NULL;

        while ((rtg = xfs_rtgroup_next(mp, rtg))) {
                xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                error = xfs_rtalloc_query_all(rtg, NULL,
                                xfs_rtalloc_count_frextent, &val);
                xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                if (error) {
                        xfs_rtgroup_rele(rtg);
                        return error;
                }
        }

        spin_lock(&mp->m_sb_lock);
        mp->m_sb.sb_frextents = val;
        spin_unlock(&mp->m_sb_lock);
        xfs_set_freecounter(mp, XC_FREE_RTEXTENTS, mp->m_sb.sb_frextents);
        return 0;
}

/*
 * Read in the bmbt of an rt metadata inode so that we never have to load them
 * at runtime.  This enables the use of shared ILOCKs for rtbitmap scans.  Use
 * an empty transaction to avoid deadlocking on loops in the bmbt.
 */
static inline int
xfs_rtmount_iread_extents(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip)
{
        int                     error;

        xfs_ilock(ip, XFS_ILOCK_EXCL);

        error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
        if (error)
                goto out_unlock;

        if (xfs_inode_has_attr_fork(ip)) {
                error = xfs_iread_extents(tp, ip, XFS_ATTR_FORK);
                if (error)
                        goto out_unlock;
        }

out_unlock:
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
}

static int
xfs_rtmount_rtg(
        struct xfs_mount        *mp,
        struct xfs_trans        *tp,
        struct xfs_rtgroup      *rtg)
{
        int                     error, i;

        for (i = 0; i < XFS_RTGI_MAX; i++) {
                error = xfs_rtginode_load(rtg, i, tp);
                if (error)
                        return error;

                if (rtg->rtg_inodes[i]) {
                        error = xfs_rtmount_iread_extents(tp,
                                        rtg->rtg_inodes[i]);
                        if (error)
                                return error;
                }
        }

        if (xfs_has_zoned(mp))
                return 0;
        return xfs_alloc_rsum_cache(rtg, mp->m_sb.sb_rbmblocks);
}

/*
 * Get the bitmap and summary inodes and the summary cache into the mount
 * structure at mount time.
 */
int
xfs_rtmount_inodes(
        struct xfs_mount        *mp)
{
        struct xfs_trans        *tp;
        struct xfs_rtgroup      *rtg = NULL;
        int                     error;

        tp = xfs_trans_alloc_empty(mp);
        if (xfs_has_rtgroups(mp) && mp->m_sb.sb_rgcount > 0) {
                error = xfs_rtginode_load_parent(tp);
                if (error)
                        goto out_cancel;
        }

        while ((rtg = xfs_rtgroup_next(mp, rtg))) {
                error = xfs_rtmount_rtg(mp, tp, rtg);
                if (error) {
                        xfs_rtgroup_rele(rtg);
                        xfs_rtunmount_inodes(mp);
                        break;
                }
        }

out_cancel:
        xfs_trans_cancel(tp);
        return error;
}

void
xfs_rtunmount_inodes(
        struct xfs_mount        *mp)
{
        struct xfs_rtgroup      *rtg = NULL;

        while ((rtg = xfs_rtgroup_next(mp, rtg)))
                xfs_rtunmount_rtg(rtg);
        xfs_rtginode_irele(&mp->m_rtdirip);
}

/*
 * Pick an extent for allocation at the start of a new realtime file.
 * Use the sequence number stored in the atime field of the bitmap inode.
 * Translate this to a fraction of the rtextents, and return the product
 * of rtextents and the fraction.
 * The fraction sequence is 0, 1/2, 1/4, 3/4, 1/8, ..., 7/8, 1/16, ...
 */
static xfs_rtxnum_t
xfs_rtpick_extent(
        struct xfs_rtgroup      *rtg,
        struct xfs_trans        *tp,
        xfs_rtxlen_t            len)            /* allocation length (rtextents) */
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_inode        *rbmip = rtg_bitmap(rtg);
        xfs_rtxnum_t            b = 0;          /* result rtext */
        int                     log2;           /* log of sequence number */
        uint64_t                resid;          /* residual after log removed */
        uint64_t                seq;            /* sequence number of file creation */
        struct timespec64       ts;             /* timespec in inode */

        xfs_assert_ilocked(rbmip, XFS_ILOCK_EXCL);

        ts = inode_get_atime(VFS_I(rbmip));
        if (!(rbmip->i_diflags & XFS_DIFLAG_NEWRTBM)) {
                rbmip->i_diflags |= XFS_DIFLAG_NEWRTBM;
                seq = 0;
        } else {
                seq = ts.tv_sec;
        }
        log2 = xfs_highbit64(seq);
        if (log2 != -1) {
                resid = seq - (1ULL << log2);
                b = (mp->m_sb.sb_rextents * ((resid << 1) + 1ULL)) >>
                    (log2 + 1);
                if (b >= mp->m_sb.sb_rextents)
                        div64_u64_rem(b, mp->m_sb.sb_rextents, &b);
                if (b + len > mp->m_sb.sb_rextents)
                        b = mp->m_sb.sb_rextents - len;
        }
        ts.tv_sec = seq + 1;
        inode_set_atime_to_ts(VFS_I(rbmip), ts);
        xfs_trans_log_inode(tp, rbmip, XFS_ILOG_CORE);
        return b;
}

static void
xfs_rtalloc_align_minmax(
        xfs_rtxlen_t            *raminlen,
        xfs_rtxlen_t            *ramaxlen,
        xfs_rtxlen_t            *prod)
{
        xfs_rtxlen_t            newmaxlen = *ramaxlen;
        xfs_rtxlen_t            newminlen = *raminlen;
        xfs_rtxlen_t            slack;

        slack = newmaxlen % *prod;
        if (slack)
                newmaxlen -= slack;
        slack = newminlen % *prod;
        if (slack)
                newminlen += *prod - slack;

        /*
         * If adjusting for extent size hint alignment produces an invalid
         * min/max len combination, go ahead without it.
         */
        if (newmaxlen < newminlen) {
                *prod = 1;
                return;
        }
        *ramaxlen = newmaxlen;
        *raminlen = newminlen;
}

/* Given a free extent, find any part of it that isn't busy, if possible. */
STATIC bool
xfs_rtalloc_check_busy(
        struct xfs_rtalloc_args *args,
        xfs_rtxnum_t            start,
        xfs_rtxlen_t            minlen_rtx,
        xfs_rtxlen_t            maxlen_rtx,
        xfs_rtxlen_t            len_rtx,
        xfs_rtxlen_t            prod,
        xfs_rtxnum_t            rtx,
        xfs_rtxlen_t            *reslen,
        xfs_rtxnum_t            *resrtx,
        unsigned                *busy_gen)
{
        struct xfs_rtgroup      *rtg = args->rtg;
        struct xfs_mount        *mp = rtg_mount(rtg);
        xfs_agblock_t           rgbno = xfs_rtx_to_rgbno(rtg, rtx);
        xfs_rgblock_t           min_rgbno = xfs_rtx_to_rgbno(rtg, start);
        xfs_extlen_t            minlen = xfs_rtxlen_to_extlen(mp, minlen_rtx);
        xfs_extlen_t            len = xfs_rtxlen_to_extlen(mp, len_rtx);
        xfs_extlen_t            diff;
        bool                    busy;

        busy = xfs_extent_busy_trim(rtg_group(rtg), minlen,
                        xfs_rtxlen_to_extlen(mp, maxlen_rtx), &rgbno, &len,
                        busy_gen);

        /*
         * If we have a largish extent that happens to start before min_rgbno,
         * see if we can shift it into range...
         */
        if (rgbno < min_rgbno && rgbno + len > min_rgbno) {
                diff = min_rgbno - rgbno;
                if (len > diff) {
                        rgbno += diff;
                        len -= diff;
                }
        }

        if (prod > 1 && len >= minlen) {
                xfs_rgblock_t   aligned_rgbno = roundup(rgbno, prod);

                diff = aligned_rgbno - rgbno;

                *resrtx = xfs_rgbno_to_rtx(mp, aligned_rgbno);
                *reslen = xfs_extlen_to_rtxlen(mp,
                                diff >= len ? 0 : len - diff);
        } else {
                *resrtx = xfs_rgbno_to_rtx(mp, rgbno);
                *reslen = xfs_extlen_to_rtxlen(mp, len);
        }

        return busy;
}

/*
 * Adjust the given free extent so that it isn't busy, or flush the log and
 * wait for the space to become unbusy.  Only needed for rtgroups.
 */
STATIC int
xfs_rtallocate_adjust_for_busy(
        struct xfs_rtalloc_args *args,
        xfs_rtxnum_t            start,
        xfs_rtxlen_t            minlen,
        xfs_rtxlen_t            maxlen,
        xfs_rtxlen_t            *len,
        xfs_rtxlen_t            prod,
        xfs_rtxnum_t            *rtx)
{
        xfs_rtxnum_t            resrtx;
        xfs_rtxlen_t            reslen;
        unsigned                busy_gen;
        bool                    busy;
        int                     error;

again:
        busy = xfs_rtalloc_check_busy(args, start, minlen, maxlen, *len, prod,
                        *rtx, &reslen, &resrtx, &busy_gen);
        if (!busy)
                return 0;

        if (reslen < minlen || (start != 0 && resrtx != *rtx)) {
                /*
                 * Enough of the extent was busy that we cannot satisfy the
                 * allocation, or this is a near allocation and the start of
                 * the extent is busy.  Flush the log and wait for the busy
                 * situation to resolve.
                 */
                trace_xfs_rtalloc_extent_busy(args->rtg, start, minlen, maxlen,
                                *len, prod, *rtx, busy_gen);

                error = xfs_extent_busy_flush(args->tp, rtg_group(args->rtg),
                                busy_gen, 0);
                if (error)
                        return error;

                goto again;
        }

        /* Some of the free space wasn't busy, hand that back to the caller. */
        trace_xfs_rtalloc_extent_busy_trim(args->rtg, *rtx, *len, resrtx,
                        reslen);
        *len = reslen;
        *rtx = resrtx;

        return 0;
}

static int
xfs_rtallocate_rtg(
        struct xfs_trans        *tp,
        xfs_rgnumber_t          rgno,
        xfs_rtblock_t           bno_hint,
        xfs_rtxlen_t            minlen,
        xfs_rtxlen_t            maxlen,
        xfs_rtxlen_t            prod,
        bool                    wasdel,
        bool                    initial_user_data,
        bool                    *rtlocked,
        xfs_rtblock_t           *bno,
        xfs_extlen_t            *blen)
{
        struct xfs_rtalloc_args args = {
                .mp             = tp->t_mountp,
                .tp             = tp,
        };
        xfs_rtxnum_t            start = 0;
        xfs_rtxnum_t            rtx;
        xfs_rtxlen_t            len = 0;
        int                     error = 0;

        args.rtg = xfs_rtgroup_grab(args.mp, rgno);
        if (!args.rtg)
                return -ENOSPC;

        /*
         * We need to lock out modifications to both the RT bitmap and summary
         * inodes for finding free space in xfs_rtallocate_extent_{near,size}
         * and join the bitmap and summary inodes for the actual allocation
         * down in xfs_rtallocate_range.
         *
         * For RTG-enabled file system we don't want to join the inodes to the
         * transaction until we are committed to allocate to allocate from this
         * RTG so that only one inode of each type is locked at a time.
         *
         * But for pre-RTG file systems we need to already to join the bitmap
         * inode to the transaction for xfs_rtpick_extent, which bumps the
         * sequence number in it, so we'll have to join the inode to the
         * transaction early here.
         *
         * This is all a bit messy, but at least the mess is contained in
         * this function.
         */
        if (!*rtlocked) {
                xfs_rtgroup_lock(args.rtg, XFS_RTGLOCK_BITMAP);
                if (!xfs_has_rtgroups(args.mp))
                        xfs_rtgroup_trans_join(tp, args.rtg,
                                        XFS_RTGLOCK_BITMAP);
                *rtlocked = true;
        }

        /*
         * For an allocation to an empty file at offset 0, pick an extent that
         * will space things out in the rt area.
         */
        if (bno_hint != NULLFSBLOCK)
                start = xfs_rtb_to_rtx(args.mp, bno_hint);
        else if (!xfs_has_rtgroups(args.mp) && initial_user_data)
                start = xfs_rtpick_extent(args.rtg, tp, maxlen);

        if (start) {
                error = xfs_rtallocate_extent_near(&args, start, minlen, maxlen,
                                &len, prod, &rtx);
                /*
                 * If we can't allocate near a specific rt extent, try again
                 * without locality criteria.
                 */
                if (error == -ENOSPC) {
                        xfs_rtbuf_cache_relse(&args);
                        error = 0;
                }
        }

        if (!error) {
                error = xfs_rtallocate_extent_size(&args, minlen, maxlen, &len,
                                prod, &rtx);
        }

        if (error) {
                if (xfs_has_rtgroups(args.mp))
                        goto out_unlock;
                goto out_release;
        }

        if (xfs_has_rtgroups(args.mp)) {
                error = xfs_rtallocate_adjust_for_busy(&args, start, minlen,
                                maxlen, &len, prod, &rtx);
                if (error)
                        goto out_unlock;

                xfs_rtgroup_trans_join(tp, args.rtg, XFS_RTGLOCK_BITMAP);
        }

        error = xfs_rtallocate_range(&args, rtx, len);
        if (error)
                goto out_release;

        xfs_trans_mod_sb(tp, wasdel ?
                        XFS_TRANS_SB_RES_FREXTENTS : XFS_TRANS_SB_FREXTENTS,
                        -(long)len);
        *bno = xfs_rtx_to_rtb(args.rtg, rtx);
        *blen = xfs_rtxlen_to_extlen(args.mp, len);

out_release:
        xfs_rtgroup_rele(args.rtg);
        xfs_rtbuf_cache_relse(&args);
        return error;
out_unlock:
        xfs_rtgroup_unlock(args.rtg, XFS_RTGLOCK_BITMAP);
        *rtlocked = false;
        goto out_release;
}

int
xfs_rtallocate_rtgs(
        struct xfs_trans        *tp,
        xfs_fsblock_t           bno_hint,
        xfs_rtxlen_t            minlen,
        xfs_rtxlen_t            maxlen,
        xfs_rtxlen_t            prod,
        bool                    wasdel,
        bool                    initial_user_data,
        xfs_rtblock_t           *bno,
        xfs_extlen_t            *blen)
{
        struct xfs_mount        *mp = tp->t_mountp;
        xfs_rgnumber_t          start_rgno, rgno;
        int                     error;

        /*
         * For now this just blindly iterates over the RTGs for an initial
         * allocation.  We could try to keep an in-memory rtg_longest member
         * to avoid the locking when just looking for big enough free space,
         * but for now this keeps things simple.
         */
        if (bno_hint != NULLFSBLOCK)
                start_rgno = xfs_rtb_to_rgno(mp, bno_hint);
        else
                start_rgno = (atomic_inc_return(&mp->m_rtgrotor) - 1) %
                                mp->m_sb.sb_rgcount;

        rgno = start_rgno;
        do {
                bool            rtlocked = false;

                error = xfs_rtallocate_rtg(tp, rgno, bno_hint, minlen, maxlen,
                                prod, wasdel, initial_user_data, &rtlocked,
                                bno, blen);
                if (error != -ENOSPC)
                        return error;
                ASSERT(!rtlocked);

                if (++rgno == mp->m_sb.sb_rgcount)
                        rgno = 0;
                bno_hint = NULLFSBLOCK;
        } while (rgno != start_rgno);

        return -ENOSPC;
}

static int
xfs_rtallocate_align(
        struct xfs_bmalloca     *ap,
        xfs_rtxlen_t            *ralen,
        xfs_rtxlen_t            *raminlen,
        xfs_rtxlen_t            *prod,
        bool                    *noalign)
{
        struct xfs_mount        *mp = ap->ip->i_mount;
        xfs_fileoff_t           orig_offset = ap->offset;
        xfs_extlen_t            minlen = mp->m_sb.sb_rextsize;
        xfs_extlen_t            align;  /* minimum allocation alignment */
        xfs_extlen_t            mod;    /* product factor for allocators */
        int                     error;

        if (*noalign) {
                align = mp->m_sb.sb_rextsize;
        } else {
                if (ap->flags & XFS_BMAPI_COWFORK)
                        align = xfs_get_cowextsz_hint(ap->ip);
                else
                        align = xfs_get_extsz_hint(ap->ip);
                if (!align)
                        align = 1;
                if (align == mp->m_sb.sb_rextsize)
                        *noalign = true;
        }

        error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, align, 1,
                        ap->eof, 0, ap->conv, &ap->offset, &ap->length);
        if (error)
                return error;
        ASSERT(ap->length);
        ASSERT(xfs_extlen_to_rtxmod(mp, ap->length) == 0);

        /*
         * If we shifted the file offset downward to satisfy an extent size
         * hint, increase minlen by that amount so that the allocator won't
         * give us an allocation that's too short to cover at least one of the
         * blocks that the caller asked for.
         */
        if (ap->offset != orig_offset)
                minlen += orig_offset - ap->offset;

        /*
         * Set ralen to be the actual requested length in rtextents.
         *
         * If the old value was close enough to XFS_BMBT_MAX_EXTLEN that
         * we rounded up to it, cut it back so it's valid again.
         * Note that if it's a really large request (bigger than
         * XFS_BMBT_MAX_EXTLEN), we don't hear about that number, and can't
         * adjust the starting point to match it.
         */
        *ralen = xfs_extlen_to_rtxlen(mp, min(ap->length, XFS_MAX_BMBT_EXTLEN));
        *raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
        ASSERT(*raminlen > 0);
        ASSERT(*raminlen <= *ralen);

        /*
         * Only bother calculating a real prod factor if offset & length are
         * perfectly aligned, otherwise it will just get us in trouble.
         */
        div_u64_rem(ap->offset, align, &mod);
        if (mod || ap->length % align)
                *prod = 1;
        else
                *prod = xfs_extlen_to_rtxlen(mp, align);

        if (*prod > 1)
                xfs_rtalloc_align_minmax(raminlen, ralen, prod);
        return 0;
}

int
xfs_bmap_rtalloc(
        struct xfs_bmalloca     *ap)
{
        xfs_fileoff_t           orig_offset = ap->offset;
        xfs_rtxlen_t            prod = 0;  /* product factor for allocators */
        xfs_rtxlen_t            ralen = 0; /* realtime allocation length */
        xfs_rtblock_t           bno_hint = NULLRTBLOCK;
        xfs_extlen_t            orig_length = ap->length;
        xfs_rtxlen_t            raminlen;
        bool                    rtlocked = false;
        bool                    noalign = false;
        bool                    initial_user_data =
                ap->datatype & XFS_ALLOC_INITIAL_USER_DATA;
        int                     error;

        ASSERT(!xfs_has_zoned(ap->tp->t_mountp));

retry:
        error = xfs_rtallocate_align(ap, &ralen, &raminlen, &prod, &noalign);
        if (error)
                return error;

        if (xfs_bmap_adjacent(ap))
                bno_hint = ap->blkno;

        if (xfs_has_rtgroups(ap->ip->i_mount)) {
                error = xfs_rtallocate_rtgs(ap->tp, bno_hint, raminlen, ralen,
                                prod, ap->wasdel, initial_user_data,
                                &ap->blkno, &ap->length);
        } else {
                error = xfs_rtallocate_rtg(ap->tp, 0, bno_hint, raminlen, ralen,
                                prod, ap->wasdel, initial_user_data,
                                &rtlocked, &ap->blkno, &ap->length);
        }

        if (error == -ENOSPC) {
                if (!noalign) {
                        /*
                         * We previously enlarged the request length to try to
                         * satisfy an extent size hint.  The allocator didn't
                         * return anything, so reset the parameters to the
                         * original values and try again without alignment
                         * criteria.
                         */
                        ap->offset = orig_offset;
                        ap->length = orig_length;
                        noalign = true;
                        goto retry;
                }

                ap->blkno = NULLFSBLOCK;
                ap->length = 0;
                return 0;
        }
        if (error)
                return error;

        xfs_bmap_alloc_account(ap);
        return 0;
}