2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "xfs_trans.h"
24 #include "xfs_alloc.h"
25 #include "xfs_quota.h"
26 #include "xfs_mount.h"
27 #include "xfs_bmap_btree.h"
28 #include "xfs_alloc_btree.h"
29 #include "xfs_ialloc_btree.h"
30 #include "xfs_dinode.h"
31 #include "xfs_inode.h"
32 #include "xfs_inode_item.h"
33 #include "xfs_btree.h"
35 #include "xfs_rtalloc.h"
36 #include "xfs_error.h"
37 #include "xfs_itable.h"
39 #include "xfs_buf_item.h"
40 #include "xfs_trans_space.h"
41 #include "xfs_utils.h"
42 #include "xfs_iomap.h"
43 #include "xfs_trace.h"
44 #include "xfs_icache.h"
45 #include "xfs_dquot_item.h"
46 #include "xfs_dquot.h"
49 #define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \
51 #define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP
54 xfs_iomap_eof_align_last_fsb(
58 xfs_fileoff_t *last_fsb)
60 xfs_fileoff_t new_last_fsb = 0;
61 xfs_extlen_t align = 0;
64 if (!XFS_IS_REALTIME_INODE(ip)) {
66 * Round up the allocation request to a stripe unit
67 * (m_dalign) boundary if the file size is >= stripe unit
68 * size, and we are allocating past the allocation eof.
70 * If mounted with the "-o swalloc" option the alignment is
71 * increased from the strip unit size to the stripe width.
73 if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
75 else if (mp->m_dalign)
78 if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
79 new_last_fsb = roundup_64(*last_fsb, align);
83 * Always round up the allocation request to an extent boundary
84 * (when file on a real-time subvolume or has di_extsize hint).
88 align = roundup_64(new_last_fsb, extsize);
91 new_last_fsb = roundup_64(*last_fsb, align);
95 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
99 *last_fsb = new_last_fsb;
105 xfs_alert_fsblock_zero(
107 xfs_bmbt_irec_t *imap)
109 xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
110 "Access to block zero in inode %llu "
111 "start_block: %llx start_off: %llx "
112 "blkcnt: %llx extent-state: %x\n",
113 (unsigned long long)ip->i_ino,
114 (unsigned long long)imap->br_startblock,
115 (unsigned long long)imap->br_startoff,
116 (unsigned long long)imap->br_blockcount,
122 xfs_iomap_write_direct(
126 xfs_bmbt_irec_t *imap,
129 xfs_mount_t *mp = ip->i_mount;
130 xfs_fileoff_t offset_fsb;
131 xfs_fileoff_t last_fsb;
132 xfs_filblks_t count_fsb, resaligned;
133 xfs_fsblock_t firstfsb;
134 xfs_extlen_t extsz, temp;
140 xfs_bmap_free_t free_list;
141 uint qblocks, resblks, resrtextents;
145 error = xfs_qm_dqattach(ip, 0);
147 return XFS_ERROR(error);
149 rt = XFS_IS_REALTIME_INODE(ip);
150 extsz = xfs_get_extsz_hint(ip);
152 offset_fsb = XFS_B_TO_FSBT(mp, offset);
153 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
154 if ((offset + count) > XFS_ISIZE(ip)) {
155 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
157 return XFS_ERROR(error);
159 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
160 last_fsb = MIN(last_fsb, (xfs_fileoff_t)
161 imap->br_blockcount +
164 count_fsb = last_fsb - offset_fsb;
165 ASSERT(count_fsb > 0);
167 resaligned = count_fsb;
168 if (unlikely(extsz)) {
169 if ((temp = do_mod(offset_fsb, extsz)))
171 if ((temp = do_mod(resaligned, extsz)))
172 resaligned += extsz - temp;
176 resrtextents = qblocks = resaligned;
177 resrtextents /= mp->m_sb.sb_rextsize;
178 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
179 quota_flag = XFS_QMOPT_RES_RTBLKS;
182 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
183 quota_flag = XFS_QMOPT_RES_REGBLKS;
187 * Allocate and setup the transaction
189 tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
190 error = xfs_trans_reserve(tp, resblks,
191 XFS_WRITE_LOG_RES(mp), resrtextents,
192 XFS_TRANS_PERM_LOG_RES,
193 XFS_WRITE_LOG_COUNT);
195 * Check for running out of space, note: need lock to return
198 xfs_trans_cancel(tp, 0);
199 return XFS_ERROR(error);
202 xfs_ilock(ip, XFS_ILOCK_EXCL);
204 error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
206 goto out_trans_cancel;
208 xfs_trans_ijoin(tp, ip, 0);
211 if (offset < XFS_ISIZE(ip) || extsz)
212 bmapi_flag |= XFS_BMAPI_PREALLOC;
215 * From this point onwards we overwrite the imap pointer that the
218 xfs_bmap_init(&free_list, &firstfsb);
220 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
221 &firstfsb, 0, imap, &nimaps, &free_list);
223 goto out_bmap_cancel;
226 * Complete the transaction
228 error = xfs_bmap_finish(&tp, &free_list, &committed);
230 goto out_bmap_cancel;
231 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
236 * Copy any maps to caller's array and return any error.
239 error = XFS_ERROR(ENOSPC);
243 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
244 error = xfs_alert_fsblock_zero(ip, imap);
247 xfs_iunlock(ip, XFS_ILOCK_EXCL);
251 xfs_bmap_cancel(&free_list);
252 xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
254 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
259 * If the caller is doing a write at the end of the file, then extend the
260 * allocation out to the file system's write iosize. We clean up any extra
261 * space left over when the file is closed in xfs_inactive().
263 * If we find we already have delalloc preallocation beyond EOF, don't do more
264 * preallocation as it it not needed.
267 xfs_iomap_eof_want_preallocate(
272 xfs_bmbt_irec_t *imap,
276 xfs_fileoff_t start_fsb;
277 xfs_filblks_t count_fsb;
278 xfs_fsblock_t firstblock;
280 int found_delalloc = 0;
283 if (offset + count <= XFS_ISIZE(ip))
287 * If the file is smaller than the minimum prealloc and we are using
288 * dynamic preallocation, don't do any preallocation at all as it is
289 * likely this is the only write to the file that is going to be done.
291 if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
292 XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
296 * If there are any real blocks past eof, then don't
297 * do any speculative allocation.
299 start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
300 count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
301 while (count_fsb > 0) {
303 firstblock = NULLFSBLOCK;
304 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
308 for (n = 0; n < imaps; n++) {
309 if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
310 (imap[n].br_startblock != DELAYSTARTBLOCK))
312 start_fsb += imap[n].br_blockcount;
313 count_fsb -= imap[n].br_blockcount;
315 if (imap[n].br_startblock == DELAYSTARTBLOCK)
325 * Determine the initial size of the preallocation. We are beyond the current
326 * EOF here, but we need to take into account whether this is a sparse write or
327 * an extending write when determining the preallocation size. Hence we need to
328 * look up the extent that ends at the current write offset and use the result
329 * to determine the preallocation size.
331 * If the extent is a hole, then preallocation is essentially disabled.
332 * Otherwise we take the size of the preceeding data extent as the basis for the
333 * preallocation size. If the size of the extent is greater than half the
334 * maximum extent length, then use the current offset as the basis. This ensures
335 * that for large files the preallocation size always extends to MAXEXTLEN
336 * rather than falling short due to things like stripe unit/width alignment of
340 xfs_iomap_eof_prealloc_initial_size(
341 struct xfs_mount *mp,
342 struct xfs_inode *ip,
344 xfs_bmbt_irec_t *imap,
347 xfs_fileoff_t start_fsb;
351 ASSERT(nimaps >= imaps);
353 /* if we are using a specific prealloc size, return now */
354 if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
357 /* If the file is small, then use the minimum prealloc */
358 if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
362 * As we write multiple pages, the offset will always align to the
363 * start of a page and hence point to a hole at EOF. i.e. if the size is
364 * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
365 * will return FSB 1. Hence if there are blocks in the file, we want to
366 * point to the block prior to the EOF block and not the hole that maps
367 * directly at @offset.
369 start_fsb = XFS_B_TO_FSB(mp, offset);
372 error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
377 if (imap[0].br_startblock == HOLESTARTBLOCK)
379 if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
380 return imap[0].br_blockcount << 1;
381 return XFS_B_TO_FSB(mp, offset);
385 xfs_quota_need_throttle(
386 struct xfs_inode *ip,
388 xfs_fsblock_t alloc_blocks)
390 struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
392 if (!dq || !xfs_this_quota_on(ip->i_mount, type))
395 /* no hi watermark, no throttle */
396 if (!dq->q_prealloc_hi_wmark)
399 /* under the lo watermark, no throttle */
400 if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark)
407 xfs_quota_calc_throttle(
408 struct xfs_inode *ip,
410 xfs_fsblock_t *qblocks,
415 struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
417 /* over hi wmark, squash the prealloc completely */
418 if (dq->q_res_bcount >= dq->q_prealloc_hi_wmark) {
423 freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount;
424 if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) {
426 if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT])
428 if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT])
432 /* only overwrite the throttle values if we are more aggressive */
433 if ((freesp >> shift) < (*qblocks >> *qshift)) {
440 * If we don't have a user specified preallocation size, dynamically increase
441 * the preallocation size as the size of the file grows. Cap the maximum size
442 * at a single extent or less if the filesystem is near full. The closer the
443 * filesystem is to full, the smaller the maximum prealocation.
446 xfs_iomap_prealloc_size(
447 struct xfs_mount *mp,
448 struct xfs_inode *ip,
450 struct xfs_bmbt_irec *imap,
453 xfs_fsblock_t alloc_blocks = 0;
456 xfs_fsblock_t qblocks;
459 alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
463 qblocks = alloc_blocks;
466 * MAXEXTLEN is not a power of two value but we round the prealloc down
467 * to the nearest power of two value after throttling. To prevent the
468 * round down from unconditionally reducing the maximum supported prealloc
469 * size, we round up first, apply appropriate throttling, round down and
470 * cap the value to MAXEXTLEN.
472 alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
475 xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
476 freesp = mp->m_sb.sb_fdblocks;
477 if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
479 if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
481 if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
483 if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
485 if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
490 * Check each quota to cap the prealloc size and provide a shift
491 * value to throttle with.
493 if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
494 xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift);
495 if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
496 xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift);
497 if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
498 xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift);
501 * The final prealloc size is set to the minimum of free space available
502 * in each of the quotas and the overall filesystem.
504 * The shift throttle value is set to the maximum value as determined by
505 * the global low free space values and per-quota low free space values.
507 alloc_blocks = MIN(alloc_blocks, qblocks);
508 shift = MAX(shift, qshift);
511 alloc_blocks >>= shift;
513 * rounddown_pow_of_two() returns an undefined result if we pass in
517 alloc_blocks = rounddown_pow_of_two(alloc_blocks);
518 if (alloc_blocks > MAXEXTLEN)
519 alloc_blocks = MAXEXTLEN;
522 * If we are still trying to allocate more space than is
523 * available, squash the prealloc hard. This can happen if we
524 * have a large file on a small filesystem and the above
525 * lowspace thresholds are smaller than MAXEXTLEN.
527 while (alloc_blocks && alloc_blocks >= freesp)
531 if (alloc_blocks < mp->m_writeio_blocks)
532 alloc_blocks = mp->m_writeio_blocks;
534 trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
535 mp->m_writeio_blocks);
541 xfs_iomap_write_delay(
545 xfs_bmbt_irec_t *ret_imap)
547 xfs_mount_t *mp = ip->i_mount;
548 xfs_fileoff_t offset_fsb;
549 xfs_fileoff_t last_fsb;
550 xfs_off_t aligned_offset;
551 xfs_fileoff_t ioalign;
554 xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
558 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
561 * Make sure that the dquots are there. This doesn't hold
562 * the ilock across a disk read.
564 error = xfs_qm_dqattach_locked(ip, 0);
566 return XFS_ERROR(error);
568 extsz = xfs_get_extsz_hint(ip);
569 offset_fsb = XFS_B_TO_FSBT(mp, offset);
571 error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
572 imap, XFS_WRITE_IMAPS, &prealloc);
578 xfs_fsblock_t alloc_blocks;
580 alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
583 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
584 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
585 last_fsb = ioalign + alloc_blocks;
587 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
590 if (prealloc || extsz) {
591 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
597 * Make sure preallocation does not create extents beyond the range we
598 * actually support in this filesystem.
600 if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
601 last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
603 ASSERT(last_fsb > offset_fsb);
605 nimaps = XFS_WRITE_IMAPS;
606 error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
607 imap, &nimaps, XFS_BMAPI_ENTIRE);
614 return XFS_ERROR(error);
618 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
619 * without EOF preallocation.
622 trace_xfs_delalloc_enospc(ip, offset, count);
628 return XFS_ERROR(error ? error : ENOSPC);
631 if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
632 return xfs_alert_fsblock_zero(ip, &imap[0]);
635 * Tag the inode as speculatively preallocated so we can reclaim this
636 * space on demand, if necessary.
639 xfs_inode_set_eofblocks_tag(ip);
646 * Pass in a delayed allocate extent, convert it to real extents;
647 * return to the caller the extent we create which maps on top of
648 * the originating callers request.
650 * Called without a lock on the inode.
652 * We no longer bother to look at the incoming map - all we have to
653 * guarantee is that whatever we allocate fills the required range.
656 xfs_iomap_write_allocate(
660 xfs_bmbt_irec_t *imap)
662 xfs_mount_t *mp = ip->i_mount;
663 xfs_fileoff_t offset_fsb, last_block;
664 xfs_fileoff_t end_fsb, map_start_fsb;
665 xfs_fsblock_t first_block;
666 xfs_bmap_free_t free_list;
667 xfs_filblks_t count_fsb;
669 int nimaps, committed;
674 * Make sure that the dquots are there.
676 error = xfs_qm_dqattach(ip, 0);
678 return XFS_ERROR(error);
680 offset_fsb = XFS_B_TO_FSBT(mp, offset);
681 count_fsb = imap->br_blockcount;
682 map_start_fsb = imap->br_startoff;
684 XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
686 while (count_fsb != 0) {
688 * Set up a transaction with which to allocate the
689 * backing store for the file. Do allocations in a
690 * loop until we get some space in the range we are
691 * interested in. The other space that might be allocated
692 * is in the delayed allocation extent on which we sit
693 * but before our buffer starts.
697 while (nimaps == 0) {
698 tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
699 tp->t_flags |= XFS_TRANS_RESERVE;
700 nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
701 error = xfs_trans_reserve(tp, nres,
702 XFS_WRITE_LOG_RES(mp),
703 0, XFS_TRANS_PERM_LOG_RES,
704 XFS_WRITE_LOG_COUNT);
706 xfs_trans_cancel(tp, 0);
707 return XFS_ERROR(error);
709 xfs_ilock(ip, XFS_ILOCK_EXCL);
710 xfs_trans_ijoin(tp, ip, 0);
712 xfs_bmap_init(&free_list, &first_block);
715 * it is possible that the extents have changed since
716 * we did the read call as we dropped the ilock for a
717 * while. We have to be careful about truncates or hole
718 * punchs here - we are not allowed to allocate
719 * non-delalloc blocks here.
721 * The only protection against truncation is the pages
722 * for the range we are being asked to convert are
723 * locked and hence a truncate will block on them
726 * As a result, if we go beyond the range we really
727 * need and hit an delalloc extent boundary followed by
728 * a hole while we have excess blocks in the map, we
729 * will fill the hole incorrectly and overrun the
730 * transaction reservation.
732 * Using a single map prevents this as we are forced to
733 * check each map we look for overlap with the desired
734 * range and abort as soon as we find it. Also, given
735 * that we only return a single map, having one beyond
736 * what we can return is probably a bit silly.
738 * We also need to check that we don't go beyond EOF;
739 * this is a truncate optimisation as a truncate sets
740 * the new file size before block on the pages we
741 * currently have locked under writeback. Because they
742 * are about to be tossed, we don't need to write them
746 end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
747 error = xfs_bmap_last_offset(NULL, ip, &last_block,
752 last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
753 if ((map_start_fsb + count_fsb) > last_block) {
754 count_fsb = last_block - map_start_fsb;
755 if (count_fsb == 0) {
762 * From this point onwards we overwrite the imap
763 * pointer that the caller gave to us.
765 error = xfs_bmapi_write(tp, ip, map_start_fsb,
767 XFS_BMAPI_STACK_SWITCH,
769 imap, &nimaps, &free_list);
773 error = xfs_bmap_finish(&tp, &free_list, &committed);
777 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
781 xfs_iunlock(ip, XFS_ILOCK_EXCL);
785 * See if we were able to allocate an extent that
786 * covers at least part of the callers request
788 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
789 return xfs_alert_fsblock_zero(ip, imap);
791 if ((offset_fsb >= imap->br_startoff) &&
792 (offset_fsb < (imap->br_startoff +
793 imap->br_blockcount))) {
794 XFS_STATS_INC(xs_xstrat_quick);
799 * So far we have not mapped the requested part of the
800 * file, just surrounding data, try again.
802 count_fsb -= imap->br_blockcount;
803 map_start_fsb = imap->br_startoff + imap->br_blockcount;
807 xfs_bmap_cancel(&free_list);
808 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
810 xfs_iunlock(ip, XFS_ILOCK_EXCL);
811 return XFS_ERROR(error);
815 xfs_iomap_write_unwritten(
820 xfs_mount_t *mp = ip->i_mount;
821 xfs_fileoff_t offset_fsb;
822 xfs_filblks_t count_fsb;
823 xfs_filblks_t numblks_fsb;
824 xfs_fsblock_t firstfsb;
827 xfs_bmbt_irec_t imap;
828 xfs_bmap_free_t free_list;
834 trace_xfs_unwritten_convert(ip, offset, count);
836 offset_fsb = XFS_B_TO_FSBT(mp, offset);
837 count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
838 count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
841 * Reserve enough blocks in this transaction for two complete extent
842 * btree splits. We may be converting the middle part of an unwritten
843 * extent and in this case we will insert two new extents in the btree
844 * each of which could cause a full split.
846 * This reservation amount will be used in the first call to
847 * xfs_bmbt_split() to select an AG with enough space to satisfy the
848 * rest of the operation.
850 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
854 * set up a transaction to convert the range of extents
855 * from unwritten to real. Do allocations in a loop until
856 * we have covered the range passed in.
858 * Note that we open code the transaction allocation here
859 * to pass KM_NOFS--we can't risk to recursing back into
860 * the filesystem here as we might be asked to write out
861 * the same inode that we complete here and might deadlock
864 sb_start_intwrite(mp->m_super);
865 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
866 tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
867 error = xfs_trans_reserve(tp, resblks,
868 XFS_WRITE_LOG_RES(mp), 0,
869 XFS_TRANS_PERM_LOG_RES,
870 XFS_WRITE_LOG_COUNT);
872 xfs_trans_cancel(tp, 0);
873 return XFS_ERROR(error);
876 xfs_ilock(ip, XFS_ILOCK_EXCL);
877 xfs_trans_ijoin(tp, ip, 0);
880 * Modify the unwritten extent state of the buffer.
882 xfs_bmap_init(&free_list, &firstfsb);
884 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
885 XFS_BMAPI_CONVERT, &firstfsb,
886 1, &imap, &nimaps, &free_list);
888 goto error_on_bmapi_transaction;
891 * Log the updated inode size as we go. We have to be careful
892 * to only log it up to the actual write offset if it is
893 * halfway into a block.
895 i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
896 if (i_size > offset + count)
897 i_size = offset + count;
899 i_size = xfs_new_eof(ip, i_size);
901 ip->i_d.di_size = i_size;
902 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
905 error = xfs_bmap_finish(&tp, &free_list, &committed);
907 goto error_on_bmapi_transaction;
909 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
910 xfs_iunlock(ip, XFS_ILOCK_EXCL);
912 return XFS_ERROR(error);
914 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
915 return xfs_alert_fsblock_zero(ip, &imap);
917 if ((numblks_fsb = imap.br_blockcount) == 0) {
919 * The numblks_fsb value should always get
920 * smaller, otherwise the loop is stuck.
922 ASSERT(imap.br_blockcount);
925 offset_fsb += numblks_fsb;
926 count_fsb -= numblks_fsb;
927 } while (count_fsb > 0);
931 error_on_bmapi_transaction:
932 xfs_bmap_cancel(&free_list);
933 xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
934 xfs_iunlock(ip, XFS_ILOCK_EXCL);
935 return XFS_ERROR(error);