Linux-2.6.33.2/fs/xfs/xfs_iomap.c
/*
* 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_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_alloc.h"
#include "xfs_dmapi.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_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_ialloc.h"
#include "xfs_btree.h"
#include "xfs_bmap.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_itable.h"
#include "xfs_rw.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_STRAT_WRITE_IMAPS 2
#define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP
STATIC int
xfs_imap_to_bmap(
xfs_inode_t *ip,
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 = ip->i_mount;
int pbm;
xfs_fsblock_t start_block;
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 (XFS_IS_REALTIME_INODE(ip)) {
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(ip, start_block);
if (ISUNWRITTEN(imap))
iomapp->iomap_flags |= IOMAP_UNWRITTEN;
}
offset += iomapp->iomap_bsize - iomapp->iomap_delta;
}
return pbm; /* Return the number filled */
}
int
xfs_iomap(
xfs_inode_t *ip,
xfs_off_t offset,
ssize_t count,
int flags,
xfs_iomap_t *iomapp,
int *niomaps)
{
xfs_mount_t *mp = ip->i_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;
ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
if (XFS_FORCED_SHUTDOWN(mp))
return XFS_ERROR(EIO);
trace_xfs_iomap_enter(ip, offset, count, flags, NULL);
switch (flags & (BMAPI_READ | BMAPI_WRITE | BMAPI_ALLOCATE)) {
case BMAPI_READ:
lockmode = xfs_ilock_map_shared(ip);
bmapi_flags = XFS_BMAPI_ENTIRE;
break;
case BMAPI_WRITE:
lockmode = XFS_ILOCK_EXCL;
if (flags & BMAPI_IGNSTATE)
bmapi_flags |= XFS_BMAPI_IGSTATE|XFS_BMAPI_ENTIRE;
xfs_ilock(ip, lockmode);
break;
case BMAPI_ALLOCATE:
lockmode = XFS_ILOCK_SHARED;
bmapi_flags = XFS_BMAPI_ENTIRE;
/* Attempt non-blocking lock */
if (flags & BMAPI_TRYLOCK) {
if (!xfs_ilock_nowait(ip, lockmode))
return XFS_ERROR(EAGAIN);
} else {
xfs_ilock(ip, lockmode);
}
break;
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(NULL, ip, offset_fsb,
(xfs_filblks_t)(end_fsb - offset_fsb),
bmapi_flags, NULL, 0, &imap,
&nimaps, NULL, NULL);
if (error)
goto out;
switch (flags & (BMAPI_WRITE|BMAPI_ALLOCATE)) {
case BMAPI_WRITE:
/* If we found an extent, return it */
if (nimaps &&
(imap.br_startblock != HOLESTARTBLOCK) &&
(imap.br_startblock != DELAYSTARTBLOCK)) {
trace_xfs_iomap_found(ip, offset, count, flags, &imap);
break;
}
if (flags & (BMAPI_DIRECT|BMAPI_MMAP)) {
error = xfs_iomap_write_direct(ip, offset, count, flags,
&imap, &nimaps, nimaps);
} else {
error = xfs_iomap_write_delay(ip, offset, count, flags,
&imap, &nimaps);
}
if (!error) {
trace_xfs_iomap_alloc(ip, offset, count, flags, &imap);
}
iomap_flags = IOMAP_NEW;
break;
case BMAPI_ALLOCATE:
/* If we found an extent, return it */
xfs_iunlock(ip, lockmode);
lockmode = 0;
if (nimaps && !isnullstartblock(imap.br_startblock)) {
trace_xfs_iomap_found(ip, offset, count, flags, &imap);
break;
}
error = xfs_iomap_write_allocate(ip, offset, count,
&imap, &nimaps);
break;
}
if (nimaps) {
*niomaps = xfs_imap_to_bmap(ip, offset, &imap,
iomapp, nimaps, *niomaps, iomap_flags);
} else if (niomaps) {
*niomaps = 0;
}
out:
if (lockmode)
xfs_iunlock(ip, lockmode);
return XFS_ERROR(error);
}
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;
int eof, error;
if (XFS_IS_REALTIME_INODE(ip))
;
/*
* 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.
*/
else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
(ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
/*
* 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 (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
/*
* 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_cmn_err_fsblock_zero(
xfs_inode_t *ip,
xfs_bmbt_irec_t *imap)
{
xfs_cmn_err(XFS_PTAG_FSBLOCK_ZERO, CE_ALERT, ip->i_mount,
"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,
int flags,
xfs_bmbt_irec_t *ret_imap,
int *nmaps,
int found)
{
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_bmbt_irec_t imap;
xfs_bmap_free_t free_list;
uint qblocks, resblks, resrtextents;
int committed;
int error;
/*
* 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);
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) > ip->i_size) {
error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
if (error)
goto error_out;
} else {
if (found && (ret_imap->br_startblock == HOLESTARTBLOCK))
last_fsb = MIN(last_fsb, (xfs_fileoff_t)
ret_imap->br_blockcount +
ret_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
*/
xfs_iunlock(ip, XFS_ILOCK_EXCL);
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);
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (error)
goto error_out;
error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
if (error)
goto error1;
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_ihold(tp, ip);
bmapi_flag = XFS_BMAPI_WRITE;
if ((flags & BMAPI_DIRECT) && (offset < ip->i_size || extsz))
bmapi_flag |= XFS_BMAPI_PREALLOC;
/*
* Issue the xfs_bmapi() call to allocate the blocks
*/
xfs_bmap_init(&free_list, &firstfsb);
nimaps = 1;
error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,
&firstfsb, 0, &imap, &nimaps, &free_list, NULL);
if (error)
goto error0;
/*
* Complete the transaction
*/
error = xfs_bmap_finish(&tp, &free_list, &committed);
if (error)
goto error0;
error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
if (error)
goto error_out;
/*
* Copy any maps to caller's array and return any error.
*/
if (nimaps == 0) {
error = ENOSPC;
goto error_out;
}
if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) {
error = xfs_cmn_err_fsblock_zero(ip, &imap);
goto error_out;
}
*ret_imap = imap;
*nmaps = 1;
return 0;
error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
xfs_bmap_cancel(&free_list);
xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
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);
}
/*
* 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().
*/
STATIC int
xfs_iomap_eof_want_preallocate(
xfs_mount_t *mp,
xfs_inode_t *ip,
xfs_off_t offset,
size_t count,
int ioflag,
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;
*prealloc = 0;
if ((offset + count) <= ip->i_size)
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, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
while (count_fsb > 0) {
imaps = nimaps;
firstblock = NULLFSBLOCK;
error = xfs_bmapi(NULL, ip, start_fsb, count_fsb, 0,
&firstblock, 0, imap, &imaps, NULL, NULL);
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;
}
}
*prealloc = 1;
return 0;
}
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_fileoff_t offset_fsb;
xfs_fileoff_t last_fsb;
xfs_off_t aligned_offset;
xfs_fileoff_t ioalign;
xfs_fsblock_t firstblock;
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,
ioflag, imap, XFS_WRITE_IMAPS, &prealloc);
if (error)
return error;
retry:
if (prealloc) {
aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
last_fsb = ioalign + mp->m_writeio_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;
}
nimaps = XFS_WRITE_IMAPS;
firstblock = NULLFSBLOCK;
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, NULL);
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 - flush all other inodes with
* delalloc blocks and retry without EOF preallocation.
*/
if (nimaps == 0) {
trace_xfs_delalloc_enospc(ip, offset, count);
if (flushed)
return XFS_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_cmn_err_fsblock_zero(ip, &imap[0]);
*ret_imap = imap[0];
*nmaps = 1;
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 *map,
int *retmap)
{
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_bmbt_irec_t imap;
xfs_trans_t *tp;
int nimaps, committed;
int error = 0;
int nres;
*retmap = 0;
/*
* 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 = 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);
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, XFS_ILOCK_EXCL);
xfs_trans_ihold(tp, ip);
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, ip->i_size);
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;
}
}
/* 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, NULL);
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_cmn_err_fsblock_zero(ip, &imap);
if ((offset_fsb >= imap.br_startoff) &&
(offset_fsb < (imap.br_startoff +
imap.br_blockcount))) {
*map = imap;
*retmap = 1;
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;
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.
*/
xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
tp->t_flags |= XFS_TRANS_RESERVE;
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, 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|XFS_BMAPI_CONVERT, &firstfsb,
1, &imap, &nimaps, &free_list, NULL);
if (error)
goto error_on_bmapi_transaction;
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_cmn_err_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);
}