xfs_iomap.c

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/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_alloc.h"
#include "xfs_quota.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_bmap.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_itable.h"
#include "xfs_attr.h"
#include "xfs_buf_item.h"
#include "xfs_trans_space.h"
#include "xfs_utils.h"
#include "xfs_iomap.h"
#include "xfs_trace.h"


#define XFS_WRITEIO_ALIGN(mp,off)   (((off) >> mp->m_writeio_log) \
                        << mp->m_writeio_log)
#define XFS_WRITE_IMAPS     XFS_BMAP_MAX_NMAP

STATIC int
xfs_iomap_eof_align_last_fsb(
    xfs_mount_t *mp,
    xfs_inode_t *ip,
    xfs_extlen_t    extsize,
    xfs_fileoff_t   *last_fsb)
{
    xfs_fileoff_t   new_last_fsb = 0;
    xfs_extlen_t    align = 0;
    int     eof, error;

    if (!XFS_IS_REALTIME_INODE(ip)) {
        /*
         * Round up the allocation request to a stripe unit
         * (m_dalign) boundary if the file size is >= stripe unit
         * size, and we are allocating past the allocation eof.
         *
         * If mounted with the "-o swalloc" option the alignment is
         * increased from the strip unit size to the stripe width.
         */
        if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
            align = mp->m_swidth;
        else if (mp->m_dalign)
            align = mp->m_dalign;

        if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
            new_last_fsb = roundup_64(*last_fsb, align);
    }

    /*
     * Always round up the allocation request to an extent boundary
     * (when file on a real-time subvolume or has di_extsize hint).
     */
    if (extsize) {
        if (new_last_fsb)
            align = roundup_64(new_last_fsb, extsize);
        else
            align = extsize;
        new_last_fsb = roundup_64(*last_fsb, align);
    }

    if (new_last_fsb) {
        error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
        if (error)
            return error;
        if (eof)
            *last_fsb = new_last_fsb;
    }
    return 0;
}

STATIC int
xfs_alert_fsblock_zero(
    xfs_inode_t *ip,
    xfs_bmbt_irec_t *imap)
{
    xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
            "Access to block zero in inode %llu "
            "start_block: %llx start_off: %llx "
            "blkcnt: %llx extent-state: %x\n",
        (unsigned long long)ip->i_ino,
        (unsigned long long)imap->br_startblock,
        (unsigned long long)imap->br_startoff,
        (unsigned long long)imap->br_blockcount,
        imap->br_state);
    return EFSCORRUPTED;
}

int
xfs_iomap_write_direct(
    xfs_inode_t *ip,
    xfs_off_t   offset,
    size_t      count,
    xfs_bmbt_irec_t *imap,
    int     nmaps)
{
    xfs_mount_t *mp = ip->i_mount;
    xfs_fileoff_t   offset_fsb;
    xfs_fileoff_t   last_fsb;
    xfs_filblks_t   count_fsb, resaligned;
    xfs_fsblock_t   firstfsb;
    xfs_extlen_t    extsz, temp;
    int     nimaps;
    int     bmapi_flag;
    int     quota_flag;
    int     rt;
    xfs_trans_t *tp;
    xfs_bmap_free_t free_list;
    uint        qblocks, resblks, resrtextents;
    int     committed;
    int     error;

    error = xfs_qm_dqattach(ip, 0);
    if (error)
        return XFS_ERROR(error);

    rt = XFS_IS_REALTIME_INODE(ip);
    extsz = xfs_get_extsz_hint(ip);

    offset_fsb = XFS_B_TO_FSBT(mp, offset);
    last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
    if ((offset + count) > XFS_ISIZE(ip)) {
        error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
        if (error)
            return XFS_ERROR(error);
    } else {
        if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
            last_fsb = MIN(last_fsb, (xfs_fileoff_t)
                    imap->br_blockcount +
                    imap->br_startoff);
    }
    count_fsb = last_fsb - offset_fsb;
    ASSERT(count_fsb > 0);

    resaligned = count_fsb;
    if (unlikely(extsz)) {
        if ((temp = do_mod(offset_fsb, extsz)))
            resaligned += temp;
        if ((temp = do_mod(resaligned, extsz)))
            resaligned += extsz - temp;
    }

    if (unlikely(rt)) {
        resrtextents = qblocks = resaligned;
        resrtextents /= mp->m_sb.sb_rextsize;
        resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
        quota_flag = XFS_QMOPT_RES_RTBLKS;
    } else {
        resrtextents = 0;
        resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
        quota_flag = XFS_QMOPT_RES_REGBLKS;
    }

    /*
     * Allocate and setup the transaction
     */
    tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
    error = xfs_trans_reserve(tp, resblks,
            XFS_WRITE_LOG_RES(mp), resrtextents,
            XFS_TRANS_PERM_LOG_RES,
            XFS_WRITE_LOG_COUNT);
    /*
     * Check for running out of space, note: need lock to return
     */
    if (error) {
        xfs_trans_cancel(tp, 0);
        return XFS_ERROR(error);
    }

    xfs_ilock(ip, XFS_ILOCK_EXCL);

    error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
    if (error)
        goto out_trans_cancel;

    xfs_trans_ijoin(tp, ip, 0);

    bmapi_flag = 0;
    if (offset < XFS_ISIZE(ip) || extsz)
        bmapi_flag |= XFS_BMAPI_PREALLOC;

    /*
     * From this point onwards we overwrite the imap pointer that the
     * caller gave to us.
     */
    xfs_bmap_init(&free_list, &firstfsb);
    nimaps = 1;
    error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
                &firstfsb, 0, imap, &nimaps, &free_list);
    if (error)
        goto out_bmap_cancel;

    /*
     * Complete the transaction
     */
    error = xfs_bmap_finish(&tp, &free_list, &committed);
    if (error)
        goto out_bmap_cancel;
    error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
    if (error)
        goto out_unlock;

    /*
     * Copy any maps to caller's array and return any error.
     */
    if (nimaps == 0) {
        error = XFS_ERROR(ENOSPC);
        goto out_unlock;
    }

    if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
        error = xfs_alert_fsblock_zero(ip, imap);

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

out_bmap_cancel:
    xfs_bmap_cancel(&free_list);
    xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
out_trans_cancel:
    xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
    goto out_unlock;
}

/*
 * If the caller is doing a write at the end of the file, then extend the
 * allocation out to the file system's write iosize.  We clean up any extra
 * space left over when the file is closed in xfs_inactive().
 *
 * If we find we already have delalloc preallocation beyond EOF, don't do more
 * preallocation as it it not needed.
 */
STATIC int
xfs_iomap_eof_want_preallocate(
    xfs_mount_t *mp,
    xfs_inode_t *ip,
    xfs_off_t   offset,
    size_t      count,
    xfs_bmbt_irec_t *imap,
    int     nimaps,
    int     *prealloc)
{
    xfs_fileoff_t   start_fsb;
    xfs_filblks_t   count_fsb;
    xfs_fsblock_t   firstblock;
    int     n, error, imaps;
    int     found_delalloc = 0;

    *prealloc = 0;
    if (offset + count <= XFS_ISIZE(ip))
        return 0;

    /*
     * If there are any real blocks past eof, then don't
     * do any speculative allocation.
     */
    start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
    count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
    while (count_fsb > 0) {
        imaps = nimaps;
        firstblock = NULLFSBLOCK;
        error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
                       0);
        if (error)
            return error;
        for (n = 0; n < imaps; n++) {
            if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
                (imap[n].br_startblock != DELAYSTARTBLOCK))
                return 0;
            start_fsb += imap[n].br_blockcount;
            count_fsb -= imap[n].br_blockcount;

            if (imap[n].br_startblock == DELAYSTARTBLOCK)
                found_delalloc = 1;
        }
    }
    if (!found_delalloc)
        *prealloc = 1;
    return 0;
}

/*
 * If we don't have a user specified preallocation size, dynamically increase
 * the preallocation size as the size of the file grows. Cap the maximum size
 * at a single extent or less if the filesystem is near full. The closer the
 * filesystem is to full, the smaller the maximum prealocation.
 */
STATIC xfs_fsblock_t
xfs_iomap_prealloc_size(
    struct xfs_mount    *mp,
    struct xfs_inode    *ip)
{
    xfs_fsblock_t       alloc_blocks = 0;

    if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
        int shift = 0;
        int64_t freesp;

        /*
         * rounddown_pow_of_two() returns an undefined result
         * if we pass in alloc_blocks = 0. Hence the "+ 1" to
         * ensure we always pass in a non-zero value.
         */
        alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
        alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
                    rounddown_pow_of_two(alloc_blocks));

        xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
        freesp = mp->m_sb.sb_fdblocks;
        if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
            shift = 2;
            if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
                shift++;
            if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
                shift++;
            if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
                shift++;
            if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
                shift++;
        }
        if (shift)
            alloc_blocks >>= shift;
    }

    if (alloc_blocks < mp->m_writeio_blocks)
        alloc_blocks = mp->m_writeio_blocks;

    return alloc_blocks;
}

int
xfs_iomap_write_delay(
    xfs_inode_t *ip,
    xfs_off_t   offset,
    size_t      count,
    xfs_bmbt_irec_t *ret_imap)
{
    xfs_mount_t *mp = ip->i_mount;
    xfs_fileoff_t   offset_fsb;
    xfs_fileoff_t   last_fsb;
    xfs_off_t   aligned_offset;
    xfs_fileoff_t   ioalign;
    xfs_extlen_t    extsz;
    int     nimaps;
    xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
    int     prealloc, flushed = 0;
    int     error;

    ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

    /*
     * Make sure that the dquots are there. This doesn't hold
     * the ilock across a disk read.
     */
    error = xfs_qm_dqattach_locked(ip, 0);
    if (error)
        return XFS_ERROR(error);

    extsz = xfs_get_extsz_hint(ip);
    offset_fsb = XFS_B_TO_FSBT(mp, offset);


    error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
                imap, XFS_WRITE_IMAPS, &prealloc);
    if (error)
        return error;

retry:
    if (prealloc) {
        xfs_fsblock_t   alloc_blocks = xfs_iomap_prealloc_size(mp, ip);

        aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
        ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
        last_fsb = ioalign + alloc_blocks;
    } else {
        last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
    }

    if (prealloc || extsz) {
        error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
        if (error)
            return error;
    }

    /*
     * Make sure preallocation does not create extents beyond the range we
     * actually support in this filesystem.
     */
    if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
        last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);

    ASSERT(last_fsb > offset_fsb);

    nimaps = XFS_WRITE_IMAPS;
    error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
                imap, &nimaps, XFS_BMAPI_ENTIRE);
    switch (error) {
    case 0:
    case ENOSPC:
    case EDQUOT:
        break;
    default:
        return XFS_ERROR(error);
    }

    /*
     * If bmapi returned us nothing, we got either ENOSPC or EDQUOT.  For
     * ENOSPC, * flush all other inodes with delalloc blocks to free up
     * some of the excess reserved metadata space. For both cases, retry
     * without EOF preallocation.
     */
    if (nimaps == 0) {
        trace_xfs_delalloc_enospc(ip, offset, count);
        if (flushed)
            return XFS_ERROR(error ? error : ENOSPC);

        if (error == ENOSPC) {
            xfs_iunlock(ip, XFS_ILOCK_EXCL);
            xfs_flush_inodes(ip);
            xfs_ilock(ip, XFS_ILOCK_EXCL);
        }

        flushed = 1;
        error = 0;
        prealloc = 0;
        goto retry;
    }

    if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
        return xfs_alert_fsblock_zero(ip, &imap[0]);

    *ret_imap = imap[0];
    return 0;
}

/*
 * Pass in a delayed allocate extent, convert it to real extents;
 * return to the caller the extent we create which maps on top of
 * the originating callers request.
 *
 * Called without a lock on the inode.
 *
 * We no longer bother to look at the incoming map - all we have to
 * guarantee is that whatever we allocate fills the required range.
 */
int
xfs_iomap_write_allocate(
    xfs_inode_t *ip,
    xfs_off_t   offset,
    size_t      count,
    xfs_bmbt_irec_t *imap)
{
    xfs_mount_t *mp = ip->i_mount;
    xfs_fileoff_t   offset_fsb, last_block;
    xfs_fileoff_t   end_fsb, map_start_fsb;
    xfs_fsblock_t   first_block;
    xfs_bmap_free_t free_list;
    xfs_filblks_t   count_fsb;
    xfs_trans_t *tp;
    int     nimaps, committed;
    int     error = 0;
    int     nres;

    /*
     * Make sure that the dquots are there.
     */
    error = xfs_qm_dqattach(ip, 0);
    if (error)
        return XFS_ERROR(error);

    offset_fsb = XFS_B_TO_FSBT(mp, offset);
    count_fsb = imap->br_blockcount;
    map_start_fsb = imap->br_startoff;

    XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));

    while (count_fsb != 0) {
        /*
         * Set up a transaction with which to allocate the
         * backing store for the file.  Do allocations in a
         * loop until we get some space in the range we are
         * interested in.  The other space that might be allocated
         * is in the delayed allocation extent on which we sit
         * but before our buffer starts.
         */

        nimaps = 0;
        while (nimaps == 0) {
            tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
            tp->t_flags |= XFS_TRANS_RESERVE;
            nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
            error = xfs_trans_reserve(tp, nres,
                    XFS_WRITE_LOG_RES(mp),
                    0, XFS_TRANS_PERM_LOG_RES,
                    XFS_WRITE_LOG_COUNT);
            if (error) {
                xfs_trans_cancel(tp, 0);
                return XFS_ERROR(error);
            }
            xfs_ilock(ip, XFS_ILOCK_EXCL);
            xfs_trans_ijoin(tp, ip, 0);

            xfs_bmap_init(&free_list, &first_block);

            /*
             * it is possible that the extents have changed since
             * we did the read call as we dropped the ilock for a
             * while. We have to be careful about truncates or hole
             * punchs here - we are not allowed to allocate
             * non-delalloc blocks here.
             *
             * The only protection against truncation is the pages
             * for the range we are being asked to convert are
             * locked and hence a truncate will block on them
             * first.
             *
             * As a result, if we go beyond the range we really
             * need and hit an delalloc extent boundary followed by
             * a hole while we have excess blocks in the map, we
             * will fill the hole incorrectly and overrun the
             * transaction reservation.
             *
             * Using a single map prevents this as we are forced to
             * check each map we look for overlap with the desired
             * range and abort as soon as we find it. Also, given
             * that we only return a single map, having one beyond
             * what we can return is probably a bit silly.
             *
             * We also need to check that we don't go beyond EOF;
             * this is a truncate optimisation as a truncate sets
             * the new file size before block on the pages we
             * currently have locked under writeback. Because they
             * are about to be tossed, we don't need to write them
             * back....
             */
            nimaps = 1;
            end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
            error = xfs_bmap_last_offset(NULL, ip, &last_block,
                            XFS_DATA_FORK);
            if (error)
                goto trans_cancel;

            last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
            if ((map_start_fsb + count_fsb) > last_block) {
                count_fsb = last_block - map_start_fsb;
                if (count_fsb == 0) {
                    error = EAGAIN;
                    goto trans_cancel;
                }
            }

            /*
             * From this point onwards we overwrite the imap
             * pointer that the caller gave to us.
             */
            error = xfs_bmapi_write(tp, ip, map_start_fsb,
                        count_fsb,
                        XFS_BMAPI_STACK_SWITCH,
                        &first_block, 1,
                        imap, &nimaps, &free_list);
            if (error)
                goto trans_cancel;

            error = xfs_bmap_finish(&tp, &free_list, &committed);
            if (error)
                goto trans_cancel;

            error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
            if (error)
                goto error0;

            xfs_iunlock(ip, XFS_ILOCK_EXCL);
        }

        /*
         * See if we were able to allocate an extent that
         * covers at least part of the callers request
         */
        if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
            return xfs_alert_fsblock_zero(ip, imap);

        if ((offset_fsb >= imap->br_startoff) &&
            (offset_fsb < (imap->br_startoff +
                   imap->br_blockcount))) {
            XFS_STATS_INC(xs_xstrat_quick);
            return 0;
        }

        /*
         * So far we have not mapped the requested part of the
         * file, just surrounding data, try again.
         */
        count_fsb -= imap->br_blockcount;
        map_start_fsb = imap->br_startoff + imap->br_blockcount;
    }

trans_cancel:
    xfs_bmap_cancel(&free_list);
    xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
error0:
    xfs_iunlock(ip, XFS_ILOCK_EXCL);
    return XFS_ERROR(error);
}

int
xfs_iomap_write_unwritten(
    xfs_inode_t *ip,
    xfs_off_t   offset,
    size_t      count)
{
    xfs_mount_t *mp = ip->i_mount;
    xfs_fileoff_t   offset_fsb;
    xfs_filblks_t   count_fsb;
    xfs_filblks_t   numblks_fsb;
    xfs_fsblock_t   firstfsb;
    int     nimaps;
    xfs_trans_t *tp;
    xfs_bmbt_irec_t imap;
    xfs_bmap_free_t free_list;
    xfs_fsize_t i_size;
    uint        resblks;
    int     committed;
    int     error;

    trace_xfs_unwritten_convert(ip, offset, count);

    offset_fsb = XFS_B_TO_FSBT(mp, offset);
    count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
    count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);

    /*
     * Reserve enough blocks in this transaction for two complete extent
     * btree splits.  We may be converting the middle part of an unwritten
     * extent and in this case we will insert two new extents in the btree
     * each of which could cause a full split.
     *
     * This reservation amount will be used in the first call to
     * xfs_bmbt_split() to select an AG with enough space to satisfy the
     * rest of the operation.
     */
    resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;

    do {
        /*
         * set up a transaction to convert the range of extents
         * from unwritten to real. Do allocations in a loop until
         * we have covered the range passed in.
         *
         * Note that we open code the transaction allocation here
         * to pass KM_NOFS--we can't risk to recursing back into
         * the filesystem here as we might be asked to write out
         * the same inode that we complete here and might deadlock
         * on the iolock.
         */
        sb_start_intwrite(mp->m_super);
        tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
        tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
        error = xfs_trans_reserve(tp, resblks,
                XFS_WRITE_LOG_RES(mp), 0,
                XFS_TRANS_PERM_LOG_RES,
                XFS_WRITE_LOG_COUNT);
        if (error) {
            xfs_trans_cancel(tp, 0);
            return XFS_ERROR(error);
        }

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

        /*
         * Modify the unwritten extent state of the buffer.
         */
        xfs_bmap_init(&free_list, &firstfsb);
        nimaps = 1;
        error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
                  XFS_BMAPI_CONVERT, &firstfsb,
                  1, &imap, &nimaps, &free_list);
        if (error)
            goto error_on_bmapi_transaction;

        /*
         * Log the updated inode size as we go.  We have to be careful
         * to only log it up to the actual write offset if it is
         * halfway into a block.
         */
        i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
        if (i_size > offset + count)
            i_size = offset + count;

        i_size = xfs_new_eof(ip, i_size);
        if (i_size) {
            ip->i_d.di_size = i_size;
            xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        }

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
            goto error_on_bmapi_transaction;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        if (error)
            return XFS_ERROR(error);

        if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
            return xfs_alert_fsblock_zero(ip, &imap);

        if ((numblks_fsb = imap.br_blockcount) == 0) {
            /*
             * The numblks_fsb value should always get
             * smaller, otherwise the loop is stuck.
             */
            ASSERT(imap.br_blockcount);
            break;
        }
        offset_fsb += numblks_fsb;
        count_fsb -= numblks_fsb;
    } while (count_fsb > 0);

    return 0;

error_on_bmapi_transaction:
    xfs_bmap_cancel(&free_list);
    xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
    xfs_iunlock(ip, XFS_ILOCK_EXCL);
    return XFS_ERROR(error);
}