[XFS] Fix a bug in xfs_iomap for extent handling of write cases

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / xfs / xfs_iomap.c

/*
 * Copyright (c) 2000-2004 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 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.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include "xfs.h"

#include "xfs_fs.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_alloc.h"
#include "xfs_dmapi.h"
#include "xfs_quota.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_bit.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_itable.h"
#include "xfs_rw.h"
#include "xfs_acl.h"
#include "xfs_cap.h"
#include "xfs_mac.h"
#include "xfs_attr.h"
#include "xfs_buf_item.h"
#include "xfs_trans_space.h"
#include "xfs_utils.h"
#include "xfs_iomap.h"

#if defined(XFS_RW_TRACE)
void
xfs_iomap_enter_trace(
        int             tag,
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        ssize_t         count)
{
        xfs_inode_t     *ip = XFS_IO_INODE(io);

        if (!ip->i_rwtrace)
                return;

        ktrace_enter(ip->i_rwtrace,
                (void *)((unsigned long)tag),
                (void *)ip,
                (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
                (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
                (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
                (void *)((unsigned long)(offset & 0xffffffff)),
                (void *)((unsigned long)count),
                (void *)((unsigned long)((io->io_new_size >> 32) & 0xffffffff)),
                (void *)((unsigned long)(io->io_new_size & 0xffffffff)),
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL);
}

void
xfs_iomap_map_trace(
        int             tag,
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        ssize_t         count,
        xfs_iomap_t     *iomapp,
        xfs_bmbt_irec_t *imapp,
        int             flags)
{
        xfs_inode_t     *ip = XFS_IO_INODE(io);

        if (!ip->i_rwtrace)
                return;

        ktrace_enter(ip->i_rwtrace,
                (void *)((unsigned long)tag),
                (void *)ip,
                (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
                (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
                (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
                (void *)((unsigned long)(offset & 0xffffffff)),
                (void *)((unsigned long)count),
                (void *)((unsigned long)flags),
                (void *)((unsigned long)((iomapp->iomap_offset >> 32) & 0xffffffff)),
                (void *)((unsigned long)(iomapp->iomap_offset & 0xffffffff)),
                (void *)((unsigned long)(iomapp->iomap_delta)),
                (void *)((unsigned long)(iomapp->iomap_bsize)),
                (void *)((unsigned long)(iomapp->iomap_bn)),
                (void *)(__psint_t)(imapp->br_startoff),
                (void *)((unsigned long)(imapp->br_blockcount)),
                (void *)(__psint_t)(imapp->br_startblock));
}
#else
#define xfs_iomap_enter_trace(tag, io, offset, count)
#define xfs_iomap_map_trace(tag, io, offset, count, iomapp, imapp, flags)
#endif

#define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
                                                << mp->m_writeio_log)
#define XFS_STRAT_WRITE_IMAPS   2
#define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP

STATIC int
xfs_imap_to_bmap(
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        xfs_bmbt_irec_t *imap,
        xfs_iomap_t     *iomapp,
        int             imaps,                  /* Number of imap entries */
        int             iomaps,                 /* Number of iomap entries */
        int             flags)
{
        xfs_mount_t     *mp;
        xfs_fsize_t     nisize;
        int             pbm;
        xfs_fsblock_t   start_block;

        mp = io->io_mount;
        nisize = XFS_SIZE(mp, io);
        if (io->io_new_size > nisize)
                nisize = io->io_new_size;

        for (pbm = 0; imaps && pbm < iomaps; imaps--, iomapp++, imap++, pbm++) {
                iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
                iomapp->iomap_delta = offset - iomapp->iomap_offset;
                iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
                iomapp->iomap_flags = flags;

                if (io->io_flags & XFS_IOCORE_RT) {
                        iomapp->iomap_flags |= IOMAP_REALTIME;
                        iomapp->iomap_target = mp->m_rtdev_targp;
                } else {
                        iomapp->iomap_target = mp->m_ddev_targp;
                }
                start_block = imap->br_startblock;
                if (start_block == HOLESTARTBLOCK) {
                        iomapp->iomap_bn = IOMAP_DADDR_NULL;
                        iomapp->iomap_flags |= IOMAP_HOLE;
                } else if (start_block == DELAYSTARTBLOCK) {
                        iomapp->iomap_bn = IOMAP_DADDR_NULL;
                        iomapp->iomap_flags |= IOMAP_DELAY;
                } else {
                        iomapp->iomap_bn = XFS_FSB_TO_DB_IO(io, start_block);
                        if (ISUNWRITTEN(imap))
                                iomapp->iomap_flags |= IOMAP_UNWRITTEN;
                }

                if ((iomapp->iomap_offset + iomapp->iomap_bsize) >= nisize) {
                        iomapp->iomap_flags |= IOMAP_EOF;
                }

                offset += iomapp->iomap_bsize - iomapp->iomap_delta;
        }
        return pbm;     /* Return the number filled */
}

int
xfs_iomap(
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        ssize_t         count,
        int             flags,
        xfs_iomap_t     *iomapp,
        int             *niomaps)
{
        xfs_mount_t     *mp = io->io_mount;
        xfs_fileoff_t   offset_fsb, end_fsb;
        int             error = 0;
        int             lockmode = 0;
        xfs_bmbt_irec_t imap;
        int             nimaps = 1;
        int             bmapi_flags = 0;
        int             iomap_flags = 0;

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        switch (flags &
                (BMAPI_READ | BMAPI_WRITE | BMAPI_ALLOCATE |
                 BMAPI_UNWRITTEN | BMAPI_DEVICE)) {
        case BMAPI_READ:
                xfs_iomap_enter_trace(XFS_IOMAP_READ_ENTER, io, offset, count);
                lockmode = XFS_LCK_MAP_SHARED(mp, io);
                bmapi_flags = XFS_BMAPI_ENTIRE;
                if (flags & BMAPI_IGNSTATE)
                        bmapi_flags |= XFS_BMAPI_IGSTATE;
                break;
        case BMAPI_WRITE:
                xfs_iomap_enter_trace(XFS_IOMAP_WRITE_ENTER, io, offset, count);
                lockmode = XFS_ILOCK_EXCL|XFS_EXTSIZE_WR;
                bmapi_flags = 0;
                XFS_ILOCK(mp, io, lockmode);
                break;
        case BMAPI_ALLOCATE:
                xfs_iomap_enter_trace(XFS_IOMAP_ALLOC_ENTER, io, offset, count);
                lockmode = XFS_ILOCK_SHARED|XFS_EXTSIZE_RD;
                bmapi_flags = XFS_BMAPI_ENTIRE;
                /* Attempt non-blocking lock */
                if (flags & BMAPI_TRYLOCK) {
                        if (!XFS_ILOCK_NOWAIT(mp, io, lockmode))
                                return XFS_ERROR(EAGAIN);
                } else {
                        XFS_ILOCK(mp, io, lockmode);
                }
                break;
        case BMAPI_UNWRITTEN:
                goto phase2;
        case BMAPI_DEVICE:
                lockmode = XFS_LCK_MAP_SHARED(mp, io);
                iomapp->iomap_target = io->io_flags & XFS_IOCORE_RT ?
                        mp->m_rtdev_targp : mp->m_ddev_targp;
                error = 0;
                *niomaps = 1;
                goto out;
        default:
                BUG();
        }

        ASSERT(offset <= mp->m_maxioffset);
        if ((xfs_fsize_t)offset + count > mp->m_maxioffset)
                count = mp->m_maxioffset - offset;
        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
        offset_fsb = XFS_B_TO_FSBT(mp, offset);

        error = XFS_BMAPI(mp, NULL, io, offset_fsb,
                        (xfs_filblks_t)(end_fsb - offset_fsb),
                        bmapi_flags,  NULL, 0, &imap,
                        &nimaps, NULL);

        if (error)
                goto out;

phase2:
        switch (flags & (BMAPI_WRITE|BMAPI_ALLOCATE|BMAPI_UNWRITTEN)) {
        case BMAPI_WRITE:
                /* If we found an extent, return it */
                if (nimaps &&
                    (imap.br_startblock != HOLESTARTBLOCK) && 
                    (imap.br_startblock != DELAYSTARTBLOCK)) {
                        xfs_iomap_map_trace(XFS_IOMAP_WRITE_MAP, io,
                                        offset, count, iomapp, &imap, flags);
                        break;
                }

                if (flags & (BMAPI_DIRECT|BMAPI_MMAP)) {
                        error = XFS_IOMAP_WRITE_DIRECT(mp, io, offset,
                                        count, flags, &imap, &nimaps, nimaps);
                } else {
                        error = XFS_IOMAP_WRITE_DELAY(mp, io, offset, count,
                                        flags, &imap, &nimaps);
                }
                if (!error) {
                        xfs_iomap_map_trace(XFS_IOMAP_ALLOC_MAP, io,
                                        offset, count, iomapp, &imap, flags);
                }
                iomap_flags = IOMAP_NEW;
                break;
        case BMAPI_ALLOCATE:
                /* If we found an extent, return it */
                XFS_IUNLOCK(mp, io, lockmode);
                lockmode = 0;

                if (nimaps && !ISNULLSTARTBLOCK(imap.br_startblock)) {
                        xfs_iomap_map_trace(XFS_IOMAP_WRITE_MAP, io,
                                        offset, count, iomapp, &imap, flags);
                        break;
                }

                error = XFS_IOMAP_WRITE_ALLOCATE(mp, io, offset, count,
                                                 &imap, &nimaps);
                break;
        case BMAPI_UNWRITTEN:
                lockmode = 0;
                error = XFS_IOMAP_WRITE_UNWRITTEN(mp, io, offset, count);
                nimaps = 0;
                break;
        }

        if (nimaps) {
                *niomaps = xfs_imap_to_bmap(io, offset, &imap,
                                            iomapp, nimaps, *niomaps, iomap_flags);
        } else if (niomaps) {
                *niomaps = 0;
        }

out:
        if (lockmode)
                XFS_IUNLOCK(mp, io, lockmode);
        return XFS_ERROR(error);
}

STATIC int
xfs_flush_space(
        xfs_inode_t     *ip,
        int             *fsynced,
        int             *ioflags)
{
        switch (*fsynced) {
        case 0:
                if (ip->i_delayed_blks) {
                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
                        xfs_flush_inode(ip);
                        xfs_ilock(ip, XFS_ILOCK_EXCL);
                        *fsynced = 1;
                } else {
                        *ioflags |= BMAPI_SYNC;
                        *fsynced = 2;
                }
                return 0;
        case 1:
                *fsynced = 2;
                *ioflags |= BMAPI_SYNC;
                return 0;
        case 2:
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                xfs_flush_device(ip);
                xfs_ilock(ip, XFS_ILOCK_EXCL);
                *fsynced = 3;
                return 0;
        }
        return 1;
}

int
xfs_iomap_write_direct(
        xfs_inode_t     *ip,
        xfs_off_t       offset,
        size_t          count,
        int             flags,
        xfs_bmbt_irec_t *ret_imap,
        int             *nmaps,
        int             found)
{
        xfs_mount_t     *mp = ip->i_mount;
        xfs_iocore_t    *io = &ip->i_iocore;
        xfs_fileoff_t   offset_fsb;
        xfs_fileoff_t   last_fsb;
        xfs_filblks_t   count_fsb;
        xfs_fsize_t     isize;
        xfs_fsblock_t   firstfsb;
        int             nimaps, maps;
        int             error;
        int             bmapi_flag;
        int             rt;
        xfs_trans_t     *tp;
        xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS], *imapp;
        xfs_bmap_free_t free_list;
        int             aeof;
        xfs_filblks_t   datablocks;
        int             committed;
        int             numrtextents;
        uint            resblks;

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

        maps = min(XFS_WRITE_IMAPS, *nmaps);
        nimaps = maps;

        isize = ip->i_d.di_size;
        aeof = (offset + count) > isize;

        if (io->io_new_size > isize)
                isize = io->io_new_size;

        offset_fsb = XFS_B_TO_FSBT(mp, offset);
        last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
        count_fsb = last_fsb - offset_fsb;
        if (found && (ret_imap->br_startblock == HOLESTARTBLOCK)) {
                xfs_fileoff_t   map_last_fsb;

                map_last_fsb = ret_imap->br_blockcount + ret_imap->br_startoff;

                if (map_last_fsb < last_fsb) {
                        last_fsb = map_last_fsb;
                        count_fsb = last_fsb - offset_fsb;
                }
                ASSERT(count_fsb > 0);
        }

        /*
         * determine if reserving space on
         * the data or realtime partition.
         */
        if ((rt = XFS_IS_REALTIME_INODE(ip))) {
                int     sbrtextsize, iprtextsize;

                sbrtextsize = mp->m_sb.sb_rextsize;
                iprtextsize =
                        ip->i_d.di_extsize ? ip->i_d.di_extsize : sbrtextsize;
                numrtextents = (count_fsb + iprtextsize - 1);
                do_div(numrtextents, sbrtextsize);
                datablocks = 0;
        } else {
                datablocks = count_fsb;
                numrtextents = 0;
        }

        /*
         * allocate and setup the transaction
         */
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);

        resblks = XFS_DIOSTRAT_SPACE_RES(mp, datablocks);

        error = xfs_trans_reserve(tp, resblks,
                        XFS_WRITE_LOG_RES(mp), numrtextents,
                        XFS_TRANS_PERM_LOG_RES,
                        XFS_WRITE_LOG_COUNT);

        /*
         * check for running out of space
         */
        if (error)
                /*
                 * Free the transaction structure.
                 */
                xfs_trans_cancel(tp, 0);

        xfs_ilock(ip, XFS_ILOCK_EXCL);

        if (error)
                goto error_out; /* Don't return in above if .. trans ..,
                                        need lock to return */

        if (XFS_TRANS_RESERVE_BLKQUOTA(mp, tp, ip, resblks)) {
                error = (EDQUOT);
                goto error1;
        }
        nimaps = 1;

        bmapi_flag = XFS_BMAPI_WRITE;
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
        xfs_trans_ihold(tp, ip);

        if (!(flags & BMAPI_MMAP) && (offset < ip->i_d.di_size || rt))
                bmapi_flag |= XFS_BMAPI_PREALLOC;

        /*
         * issue the bmapi() call to allocate the blocks
         */
        XFS_BMAP_INIT(&free_list, &firstfsb);
        imapp = &imap[0];
        error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
                bmapi_flag, &firstfsb, 0, imapp, &nimaps, &free_list);
        if (error) {
                goto error0;
        }

        /*
         * complete the transaction
         */

        error = xfs_bmap_finish(&tp, &free_list, firstfsb, &committed);
        if (error) {
                goto error0;
        }

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES, NULL);
        if (error) {
                goto error_out;
        }

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

        *ret_imap = imap[0];
        *nmaps = 1;
        if ( !(io->io_flags & XFS_IOCORE_RT)  && !ret_imap->br_startblock) {
                cmn_err(CE_PANIC,"Access to block zero:  fs <%s> inode: %lld "
                        "start_block : %llx start_off : %llx blkcnt : %llx "
                        "extent-state : %x \n",
                        (ip->i_mount)->m_fsname,
                        (long long)ip->i_ino,
                        ret_imap->br_startblock, ret_imap->br_startoff,
                        ret_imap->br_blockcount,ret_imap->br_state);
        }
        return 0;

 error0:        /* Cancel bmap, unlock inode, and cancel trans */
        xfs_bmap_cancel(&free_list);

 error1:        /* Just cancel transaction */
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
        *nmaps = 0;     /* nothing set-up here */

error_out:
        return XFS_ERROR(error);
}

int
xfs_iomap_write_delay(
        xfs_inode_t     *ip,
        xfs_off_t       offset,
        size_t          count,
        int             ioflag,
        xfs_bmbt_irec_t *ret_imap,
        int             *nmaps)
{
        xfs_mount_t     *mp = ip->i_mount;
        xfs_iocore_t    *io = &ip->i_iocore;
        xfs_fileoff_t   offset_fsb;
        xfs_fileoff_t   last_fsb;
        xfs_fsize_t     isize;
        xfs_fsblock_t   firstblock;
        int             nimaps;
        int             error;
        xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
        int             aeof;
        int             fsynced = 0;

        ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE) != 0);

        /*
         * Make sure that the dquots are there. This doesn't hold
         * the ilock across a disk read.
         */

        error = XFS_QM_DQATTACH(mp, ip, XFS_QMOPT_ILOCKED);
        if (error)
                return XFS_ERROR(error);

retry:
        isize = ip->i_d.di_size;
        if (io->io_new_size > isize) {
                isize = io->io_new_size;
        }

        aeof = 0;
        offset_fsb = XFS_B_TO_FSBT(mp, offset);
        last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
        /*
         * If the caller is doing a write at the end of the file,
         * then extend the allocation (and the buffer used for the write)
         * out to the file system's write iosize.  We clean up any extra
         * space left over when the file is closed in xfs_inactive().
         *
         * For sync writes, we are flushing delayed allocate space to
         * try to make additional space available for allocation near
         * the filesystem full boundary - preallocation hurts in that
         * situation, of course.
         */
        if (!(ioflag & BMAPI_SYNC) && ((offset + count) > ip->i_d.di_size)) {
                xfs_off_t       aligned_offset;
                xfs_filblks_t   count_fsb;
                unsigned int    iosize;
                xfs_fileoff_t   ioalign;
                int             n;
                xfs_fileoff_t   start_fsb;

                /*
                 * 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, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
                while (count_fsb > 0) {
                        nimaps = XFS_WRITE_IMAPS;
                        error = XFS_BMAPI(mp, NULL, io, start_fsb, count_fsb,
                                        0, &firstblock, 0, imap, &nimaps, NULL);
                        if (error) {
                                return error;
                        }
                        for (n = 0; n < nimaps; n++) {
                                if ( !(io->io_flags & XFS_IOCORE_RT)  && 
                                        !imap[n].br_startblock) {
                                        cmn_err(CE_PANIC,"Access to block "
                                                "zero:  fs <%s> inode: %lld "
                                                "start_block : %llx start_off "
                                                ": %llx blkcnt : %llx "
                                                "extent-state : %x \n",
                                                (ip->i_mount)->m_fsname,
                                                (long long)ip->i_ino,
                                                imap[n].br_startblock,
                                                imap[n].br_startoff,
                                                imap[n].br_blockcount,
                                                imap[n].br_state);
                                }
                                if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
                                    (imap[n].br_startblock != DELAYSTARTBLOCK)) {
                                        goto write_map;
                                }
                                start_fsb += imap[n].br_blockcount;
                                count_fsb -= imap[n].br_blockcount;
                        }
                }
                iosize = mp->m_writeio_blocks;
                aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
                ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
                last_fsb = ioalign + iosize;
                aeof = 1;
        }
write_map:
        nimaps = XFS_WRITE_IMAPS;
        firstblock = NULLFSBLOCK;

        /*
         * If mounted with the "-o swalloc" option, roundup the allocation
         * request to a stripe width boundary if the file size is >=
         * stripe width and we are allocating past the allocation eof.
         */
        if (!(io->io_flags & XFS_IOCORE_RT) && mp->m_swidth 
            && (mp->m_flags & XFS_MOUNT_SWALLOC)
            && (isize >= XFS_FSB_TO_B(mp, mp->m_swidth)) && aeof) {
                int eof;
                xfs_fileoff_t new_last_fsb;

                new_last_fsb = roundup_64(last_fsb, mp->m_swidth);
                error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
                if (error) {
                        return error;
                }
                if (eof) {
                        last_fsb = new_last_fsb;
                }
        /*
         * Roundup 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.
         */
        } else if (!(io->io_flags & XFS_IOCORE_RT) && mp->m_dalign &&
                   (isize >= XFS_FSB_TO_B(mp, mp->m_dalign)) && aeof) {
                int eof;
                xfs_fileoff_t new_last_fsb;
                new_last_fsb = roundup_64(last_fsb, mp->m_dalign);
                error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
                if (error) {
                        return error;
                }
                if (eof) {
                        last_fsb = new_last_fsb;
                }
        /*
         * Round up the allocation request to a real-time extent boundary
         * if the file is on the real-time subvolume.
         */
        } else if (io->io_flags & XFS_IOCORE_RT && aeof) {
                int eof;
                xfs_fileoff_t new_last_fsb;

                new_last_fsb = roundup_64(last_fsb, mp->m_sb.sb_rextsize);
                error = XFS_BMAP_EOF(mp, io, new_last_fsb, XFS_DATA_FORK, &eof);
                if (error) {
                        return error;
                }
                if (eof)
                        last_fsb = new_last_fsb;
        }
        error = xfs_bmapi(NULL, ip, offset_fsb,
                          (xfs_filblks_t)(last_fsb - offset_fsb),
                          XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
                          XFS_BMAPI_ENTIRE, &firstblock, 1, imap,
                          &nimaps, NULL);
        /*
         * This can be EDQUOT, if nimaps == 0
         */
        if (error && (error != ENOSPC)) {
                return XFS_ERROR(error);
        }
        /*
         * If bmapi returned us nothing, and if we didn't get back EDQUOT,
         * then we must have run out of space.
         */
        if (nimaps == 0) {
                xfs_iomap_enter_trace(XFS_IOMAP_WRITE_NOSPACE,
                                        io, offset, count);
                if (xfs_flush_space(ip, &fsynced, &ioflag))
                        return XFS_ERROR(ENOSPC);

                error = 0;
                goto retry;
        }

        *ret_imap = imap[0];
        *nmaps = 1;
        if ( !(io->io_flags & XFS_IOCORE_RT)  && !ret_imap->br_startblock) {
                cmn_err(CE_PANIC,"Access to block zero:  fs <%s> inode: %lld "
                        "start_block : %llx start_off : %llx blkcnt : %llx "
                        "extent-state : %x \n",
                        (ip->i_mount)->m_fsname,
                        (long long)ip->i_ino,
                        ret_imap->br_startblock, ret_imap->br_startoff,
                        ret_imap->br_blockcount,ret_imap->br_state);
        }
        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.
 */
int
xfs_iomap_write_allocate(
        xfs_inode_t     *ip,
        xfs_off_t       offset,
        size_t          count,
        xfs_bmbt_irec_t *map,
        int             *retmap)
{
        xfs_mount_t     *mp = ip->i_mount;
        xfs_iocore_t    *io = &ip->i_iocore;
        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_bmbt_irec_t imap[XFS_STRAT_WRITE_IMAPS];
        xfs_trans_t     *tp;
        int             i, nimaps, committed;
        int             error = 0;
        int             nres;

        *retmap = 0;

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

        offset_fsb = XFS_B_TO_FSBT(mp, offset);
        count_fsb = map->br_blockcount;
        map_start_fsb = map->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);
                        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 == ENOSPC) {
                                error = xfs_trans_reserve(tp, 0,
                                                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, XFS_ILOCK_EXCL);
                        xfs_trans_ihold(tp, ip);

                        XFS_BMAP_INIT(&free_list, &first_block);

                        nimaps = XFS_STRAT_WRITE_IMAPS;
                        /*
                         * Ensure we don't go beyond eof - it is possible
                         * the extents changed since we did the read call,
                         * we dropped the ilock in the interim.
                         */

                        end_fsb = XFS_B_TO_FSB(mp, ip->i_d.di_size);
                        xfs_bmap_last_offset(NULL, ip, &last_block,
                                XFS_DATA_FORK);
                        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;
                                }
                        }

                        /* Go get the actual blocks */
                        error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
                                        XFS_BMAPI_WRITE, &first_block, 1,
                                        imap, &nimaps, &free_list);
                        if (error)
                                goto trans_cancel;

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

                        error = xfs_trans_commit(tp,
                                        XFS_TRANS_RELEASE_LOG_RES, NULL);
                        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
                 */

                for (i = 0; i < nimaps; i++) {
                        if ( !(io->io_flags & XFS_IOCORE_RT)  && 
                                !imap[i].br_startblock) {
                                cmn_err(CE_PANIC,"Access to block zero:  "
                                        "fs <%s> inode: %lld "
                                        "start_block : %llx start_off : %llx " 
                                        "blkcnt : %llx extent-state : %x \n",
                                        (ip->i_mount)->m_fsname,
                                        (long long)ip->i_ino,
                                        imap[i].br_startblock,
                                        imap[i].br_startoff,
                                        imap[i].br_blockcount,imap[i].br_state);
                        }
                        if ((offset_fsb >= imap[i].br_startoff) &&
                            (offset_fsb < (imap[i].br_startoff +
                                           imap[i].br_blockcount))) {
                                *map = imap[i];
                                *retmap = 1;
                                XFS_STATS_INC(xs_xstrat_quick);
                                return 0;
                        }
                        count_fsb -= imap[i].br_blockcount;
                }

                /* So far we have not mapped the requested part of the
                 * file, just surrounding data, try again.
                 */
                nimaps--;
                map_start_fsb = imap[nimaps].br_startoff +
                                imap[nimaps].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_iocore_t    *io = &ip->i_iocore;
        xfs_trans_t     *tp;
        xfs_fileoff_t   offset_fsb;
        xfs_filblks_t   count_fsb;
        xfs_filblks_t   numblks_fsb;
        xfs_bmbt_irec_t imap;
        int             committed;
        int             error;
        int             nres;
        int             nimaps;
        xfs_fsblock_t   firstfsb;
        xfs_bmap_free_t free_list;

        xfs_iomap_enter_trace(XFS_IOMAP_UNWRITTEN,
                                &ip->i_iocore, 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);

        do {
                nres = XFS_DIOSTRAT_SPACE_RES(mp, 0);

                /*
                 * 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.
                 */

                tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
                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);
                        goto error0;
                }

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

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

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

                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES, NULL);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                if (error)
                        goto error0;
                
                if ( !(io->io_flags & XFS_IOCORE_RT)  && !imap.br_startblock) {
                        cmn_err(CE_PANIC,"Access to block zero:  fs <%s> "
                                "inode: %lld start_block : %llx start_off : "
                                "%llx blkcnt : %llx extent-state : %x \n",
                                (ip->i_mount)->m_fsname,
                                (long long)ip->i_ino,
                                imap.br_startblock,imap.br_startoff,
                                imap.br_blockcount,imap.br_state);
                }

                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);
error0:
        return XFS_ERROR(error);
}