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
20 #include "xfs_format.h"
22 #include "xfs_trans.h"
25 #include "xfs_alloc.h"
26 #include "xfs_quota.h"
27 #include "xfs_mount.h"
28 #include "xfs_bmap_btree.h"
29 #include "xfs_alloc_btree.h"
30 #include "xfs_ialloc_btree.h"
31 #include "xfs_dinode.h"
32 #include "xfs_inode.h"
33 #include "xfs_inode_item.h"
34 #include "xfs_btree.h"
36 #include "xfs_bmap_util.h"
37 #include "xfs_rtalloc.h"
38 #include "xfs_error.h"
39 #include "xfs_itable.h"
41 #include "xfs_buf_item.h"
42 #include "xfs_trans_space.h"
43 #include "xfs_iomap.h"
44 #include "xfs_trace.h"
45 #include "xfs_icache.h"
46 #include "xfs_dquot_item.h"
47 #include "xfs_dquot.h"
50 #define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \
52 #define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP
55 xfs_iomap_eof_align_last_fsb(
59 xfs_fileoff_t *last_fsb)
61 xfs_fileoff_t new_last_fsb = 0;
62 xfs_extlen_t align = 0;
65 if (!XFS_IS_REALTIME_INODE(ip)) {
67 * Round up the allocation request to a stripe unit
68 * (m_dalign) boundary if the file size is >= stripe unit
69 * size, and we are allocating past the allocation eof.
71 * If mounted with the "-o swalloc" option the alignment is
72 * increased from the strip unit size to the stripe width.
74 if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
76 else if (mp->m_dalign)
79 if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
80 new_last_fsb = roundup_64(*last_fsb, align);
84 * Always round up the allocation request to an extent boundary
85 * (when file on a real-time subvolume or has di_extsize hint).
89 align = roundup_64(new_last_fsb, extsize);
92 new_last_fsb = roundup_64(*last_fsb, align);
96 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
100 *last_fsb = new_last_fsb;
106 xfs_alert_fsblock_zero(
108 xfs_bmbt_irec_t *imap)
110 xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
111 "Access to block zero in inode %llu "
112 "start_block: %llx start_off: %llx "
113 "blkcnt: %llx extent-state: %x\n",
114 (unsigned long long)ip->i_ino,
115 (unsigned long long)imap->br_startblock,
116 (unsigned long long)imap->br_startoff,
117 (unsigned long long)imap->br_blockcount,
123 xfs_iomap_write_direct(
127 xfs_bmbt_irec_t *imap,
130 xfs_mount_t *mp = ip->i_mount;
131 xfs_fileoff_t offset_fsb;
132 xfs_fileoff_t last_fsb;
133 xfs_filblks_t count_fsb, resaligned;
134 xfs_fsblock_t firstfsb;
135 xfs_extlen_t extsz, temp;
141 xfs_bmap_free_t free_list;
142 uint qblocks, resblks, resrtextents;
146 error = xfs_qm_dqattach(ip, 0);
148 return XFS_ERROR(error);
150 rt = XFS_IS_REALTIME_INODE(ip);
151 extsz = xfs_get_extsz_hint(ip);
153 offset_fsb = XFS_B_TO_FSBT(mp, offset);
154 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
155 if ((offset + count) > XFS_ISIZE(ip)) {
156 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
158 return XFS_ERROR(error);
160 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
161 last_fsb = MIN(last_fsb, (xfs_fileoff_t)
162 imap->br_blockcount +
165 count_fsb = last_fsb - offset_fsb;
166 ASSERT(count_fsb > 0);
168 resaligned = count_fsb;
169 if (unlikely(extsz)) {
170 if ((temp = do_mod(offset_fsb, extsz)))
172 if ((temp = do_mod(resaligned, extsz)))
173 resaligned += extsz - temp;
177 resrtextents = qblocks = resaligned;
178 resrtextents /= mp->m_sb.sb_rextsize;
179 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
180 quota_flag = XFS_QMOPT_RES_RTBLKS;
183 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
184 quota_flag = XFS_QMOPT_RES_REGBLKS;
188 * Allocate and setup the transaction
190 tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
191 error = xfs_trans_reserve(tp, resblks,
192 XFS_WRITE_LOG_RES(mp), resrtextents,
193 XFS_TRANS_PERM_LOG_RES,
194 XFS_WRITE_LOG_COUNT);
196 * Check for running out of space, note: need lock to return
199 xfs_trans_cancel(tp, 0);
200 return XFS_ERROR(error);
203 xfs_ilock(ip, XFS_ILOCK_EXCL);
205 error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
207 goto out_trans_cancel;
209 xfs_trans_ijoin(tp, ip, 0);
212 if (offset < XFS_ISIZE(ip) || extsz)
213 bmapi_flag |= XFS_BMAPI_PREALLOC;
216 * From this point onwards we overwrite the imap pointer that the
219 xfs_bmap_init(&free_list, &firstfsb);
221 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
222 &firstfsb, 0, imap, &nimaps, &free_list);
224 goto out_bmap_cancel;
227 * Complete the transaction
229 error = xfs_bmap_finish(&tp, &free_list, &committed);
231 goto out_bmap_cancel;
232 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
237 * Copy any maps to caller's array and return any error.
240 error = XFS_ERROR(ENOSPC);
244 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
245 error = xfs_alert_fsblock_zero(ip, imap);
248 xfs_iunlock(ip, XFS_ILOCK_EXCL);
252 xfs_bmap_cancel(&free_list);
253 xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
255 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
260 * If the caller is doing a write at the end of the file, then extend the
261 * allocation out to the file system's write iosize. We clean up any extra
262 * space left over when the file is closed in xfs_inactive().
264 * If we find we already have delalloc preallocation beyond EOF, don't do more
265 * preallocation as it it not needed.
268 xfs_iomap_eof_want_preallocate(
273 xfs_bmbt_irec_t *imap,
277 xfs_fileoff_t start_fsb;
278 xfs_filblks_t count_fsb;
279 xfs_fsblock_t firstblock;
281 int found_delalloc = 0;
284 if (offset + count <= XFS_ISIZE(ip))
288 * If the file is smaller than the minimum prealloc and we are using
289 * dynamic preallocation, don't do any preallocation at all as it is
290 * likely this is the only write to the file that is going to be done.
292 if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
293 XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
297 * If there are any real blocks past eof, then don't
298 * do any speculative allocation.
300 start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
301 count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
302 while (count_fsb > 0) {
304 firstblock = NULLFSBLOCK;
305 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
309 for (n = 0; n < imaps; n++) {
310 if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
311 (imap[n].br_startblock != DELAYSTARTBLOCK))
313 start_fsb += imap[n].br_blockcount;
314 count_fsb -= imap[n].br_blockcount;
316 if (imap[n].br_startblock == DELAYSTARTBLOCK)
326 * Determine the initial size of the preallocation. We are beyond the current
327 * EOF here, but we need to take into account whether this is a sparse write or
328 * an extending write when determining the preallocation size. Hence we need to
329 * look up the extent that ends at the current write offset and use the result
330 * to determine the preallocation size.
332 * If the extent is a hole, then preallocation is essentially disabled.
333 * Otherwise we take the size of the preceeding data extent as the basis for the
334 * preallocation size. If the size of the extent is greater than half the
335 * maximum extent length, then use the current offset as the basis. This ensures
336 * that for large files the preallocation size always extends to MAXEXTLEN
337 * rather than falling short due to things like stripe unit/width alignment of
341 xfs_iomap_eof_prealloc_initial_size(
342 struct xfs_mount *mp,
343 struct xfs_inode *ip,
345 xfs_bmbt_irec_t *imap,
348 xfs_fileoff_t start_fsb;
352 ASSERT(nimaps >= imaps);
354 /* if we are using a specific prealloc size, return now */
355 if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
358 /* If the file is small, then use the minimum prealloc */
359 if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
363 * As we write multiple pages, the offset will always align to the
364 * start of a page and hence point to a hole at EOF. i.e. if the size is
365 * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
366 * will return FSB 1. Hence if there are blocks in the file, we want to
367 * point to the block prior to the EOF block and not the hole that maps
368 * directly at @offset.
370 start_fsb = XFS_B_TO_FSB(mp, offset);
373 error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
378 if (imap[0].br_startblock == HOLESTARTBLOCK)
380 if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
381 return imap[0].br_blockcount << 1;
382 return XFS_B_TO_FSB(mp, offset);
386 xfs_quota_need_throttle(
387 struct xfs_inode *ip,
389 xfs_fsblock_t alloc_blocks)
391 struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
393 if (!dq || !xfs_this_quota_on(ip->i_mount, type))
396 /* no hi watermark, no throttle */
397 if (!dq->q_prealloc_hi_wmark)
400 /* under the lo watermark, no throttle */
401 if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark)
408 xfs_quota_calc_throttle(
409 struct xfs_inode *ip,
411 xfs_fsblock_t *qblocks,
416 struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
418 /* over hi wmark, squash the prealloc completely */
419 if (dq->q_res_bcount >= dq->q_prealloc_hi_wmark) {
424 freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount;
425 if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) {
427 if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT])
429 if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT])
433 /* only overwrite the throttle values if we are more aggressive */
434 if ((freesp >> shift) < (*qblocks >> *qshift)) {
441 * If we don't have a user specified preallocation size, dynamically increase
442 * the preallocation size as the size of the file grows. Cap the maximum size
443 * at a single extent or less if the filesystem is near full. The closer the
444 * filesystem is to full, the smaller the maximum prealocation.
447 xfs_iomap_prealloc_size(
448 struct xfs_mount *mp,
449 struct xfs_inode *ip,
451 struct xfs_bmbt_irec *imap,
454 xfs_fsblock_t alloc_blocks = 0;
457 xfs_fsblock_t qblocks;
460 alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
464 qblocks = alloc_blocks;
467 * MAXEXTLEN is not a power of two value but we round the prealloc down
468 * to the nearest power of two value after throttling. To prevent the
469 * round down from unconditionally reducing the maximum supported prealloc
470 * size, we round up first, apply appropriate throttling, round down and
471 * cap the value to MAXEXTLEN.
473 alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
476 xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
477 freesp = mp->m_sb.sb_fdblocks;
478 if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
480 if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
482 if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
484 if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
486 if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
491 * Check each quota to cap the prealloc size and provide a shift
492 * value to throttle with.
494 if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
495 xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift);
496 if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
497 xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift);
498 if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
499 xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift);
502 * The final prealloc size is set to the minimum of free space available
503 * in each of the quotas and the overall filesystem.
505 * The shift throttle value is set to the maximum value as determined by
506 * the global low free space values and per-quota low free space values.
508 alloc_blocks = MIN(alloc_blocks, qblocks);
509 shift = MAX(shift, qshift);
512 alloc_blocks >>= shift;
514 * rounddown_pow_of_two() returns an undefined result if we pass in
518 alloc_blocks = rounddown_pow_of_two(alloc_blocks);
519 if (alloc_blocks > MAXEXTLEN)
520 alloc_blocks = MAXEXTLEN;
523 * If we are still trying to allocate more space than is
524 * available, squash the prealloc hard. This can happen if we
525 * have a large file on a small filesystem and the above
526 * lowspace thresholds are smaller than MAXEXTLEN.
528 while (alloc_blocks && alloc_blocks >= freesp)
532 if (alloc_blocks < mp->m_writeio_blocks)
533 alloc_blocks = mp->m_writeio_blocks;
535 trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
536 mp->m_writeio_blocks);
542 xfs_iomap_write_delay(
546 xfs_bmbt_irec_t *ret_imap)
548 xfs_mount_t *mp = ip->i_mount;
549 xfs_fileoff_t offset_fsb;
550 xfs_fileoff_t last_fsb;
551 xfs_off_t aligned_offset;
552 xfs_fileoff_t ioalign;
555 xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
559 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
562 * Make sure that the dquots are there. This doesn't hold
563 * the ilock across a disk read.
565 error = xfs_qm_dqattach_locked(ip, 0);
567 return XFS_ERROR(error);
569 extsz = xfs_get_extsz_hint(ip);
570 offset_fsb = XFS_B_TO_FSBT(mp, offset);
572 error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
573 imap, XFS_WRITE_IMAPS, &prealloc);
579 xfs_fsblock_t alloc_blocks;
581 alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
584 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
585 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
586 last_fsb = ioalign + alloc_blocks;
588 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
591 if (prealloc || extsz) {
592 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
598 * Make sure preallocation does not create extents beyond the range we
599 * actually support in this filesystem.
601 if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
602 last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
604 ASSERT(last_fsb > offset_fsb);
606 nimaps = XFS_WRITE_IMAPS;
607 error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
608 imap, &nimaps, XFS_BMAPI_ENTIRE);
615 return XFS_ERROR(error);
619 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
620 * without EOF preallocation.
623 trace_xfs_delalloc_enospc(ip, offset, count);
629 return XFS_ERROR(error ? error : ENOSPC);
632 if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
633 return xfs_alert_fsblock_zero(ip, &imap[0]);
636 * Tag the inode as speculatively preallocated so we can reclaim this
637 * space on demand, if necessary.
640 xfs_inode_set_eofblocks_tag(ip);
647 * Pass in a delayed allocate extent, convert it to real extents;
648 * return to the caller the extent we create which maps on top of
649 * the originating callers request.
651 * Called without a lock on the inode.
653 * We no longer bother to look at the incoming map - all we have to
654 * guarantee is that whatever we allocate fills the required range.
657 xfs_iomap_write_allocate(
661 xfs_bmbt_irec_t *imap)
663 xfs_mount_t *mp = ip->i_mount;
664 xfs_fileoff_t offset_fsb, last_block;
665 xfs_fileoff_t end_fsb, map_start_fsb;
666 xfs_fsblock_t first_block;
667 xfs_bmap_free_t free_list;
668 xfs_filblks_t count_fsb;
670 int nimaps, committed;
675 * Make sure that the dquots are there.
677 error = xfs_qm_dqattach(ip, 0);
679 return XFS_ERROR(error);
681 offset_fsb = XFS_B_TO_FSBT(mp, offset);
682 count_fsb = imap->br_blockcount;
683 map_start_fsb = imap->br_startoff;
685 XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
687 while (count_fsb != 0) {
689 * Set up a transaction with which to allocate the
690 * backing store for the file. Do allocations in a
691 * loop until we get some space in the range we are
692 * interested in. The other space that might be allocated
693 * is in the delayed allocation extent on which we sit
694 * but before our buffer starts.
698 while (nimaps == 0) {
699 tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
700 tp->t_flags |= XFS_TRANS_RESERVE;
701 nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
702 error = xfs_trans_reserve(tp, nres,
703 XFS_WRITE_LOG_RES(mp),
704 0, XFS_TRANS_PERM_LOG_RES,
705 XFS_WRITE_LOG_COUNT);
707 xfs_trans_cancel(tp, 0);
708 return XFS_ERROR(error);
710 xfs_ilock(ip, XFS_ILOCK_EXCL);
711 xfs_trans_ijoin(tp, ip, 0);
713 xfs_bmap_init(&free_list, &first_block);
716 * it is possible that the extents have changed since
717 * we did the read call as we dropped the ilock for a
718 * while. We have to be careful about truncates or hole
719 * punchs here - we are not allowed to allocate
720 * non-delalloc blocks here.
722 * The only protection against truncation is the pages
723 * for the range we are being asked to convert are
724 * locked and hence a truncate will block on them
727 * As a result, if we go beyond the range we really
728 * need and hit an delalloc extent boundary followed by
729 * a hole while we have excess blocks in the map, we
730 * will fill the hole incorrectly and overrun the
731 * transaction reservation.
733 * Using a single map prevents this as we are forced to
734 * check each map we look for overlap with the desired
735 * range and abort as soon as we find it. Also, given
736 * that we only return a single map, having one beyond
737 * what we can return is probably a bit silly.
739 * We also need to check that we don't go beyond EOF;
740 * this is a truncate optimisation as a truncate sets
741 * the new file size before block on the pages we
742 * currently have locked under writeback. Because they
743 * are about to be tossed, we don't need to write them
747 end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
748 error = xfs_bmap_last_offset(NULL, ip, &last_block,
753 last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
754 if ((map_start_fsb + count_fsb) > last_block) {
755 count_fsb = last_block - map_start_fsb;
756 if (count_fsb == 0) {
763 * From this point onwards we overwrite the imap
764 * pointer that the caller gave to us.
766 error = xfs_bmapi_write(tp, ip, map_start_fsb,
768 XFS_BMAPI_STACK_SWITCH,
770 imap, &nimaps, &free_list);
774 error = xfs_bmap_finish(&tp, &free_list, &committed);
778 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
782 xfs_iunlock(ip, XFS_ILOCK_EXCL);
786 * See if we were able to allocate an extent that
787 * covers at least part of the callers request
789 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
790 return xfs_alert_fsblock_zero(ip, imap);
792 if ((offset_fsb >= imap->br_startoff) &&
793 (offset_fsb < (imap->br_startoff +
794 imap->br_blockcount))) {
795 XFS_STATS_INC(xs_xstrat_quick);
800 * So far we have not mapped the requested part of the
801 * file, just surrounding data, try again.
803 count_fsb -= imap->br_blockcount;
804 map_start_fsb = imap->br_startoff + imap->br_blockcount;
808 xfs_bmap_cancel(&free_list);
809 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
811 xfs_iunlock(ip, XFS_ILOCK_EXCL);
812 return XFS_ERROR(error);
816 xfs_iomap_write_unwritten(
821 xfs_mount_t *mp = ip->i_mount;
822 xfs_fileoff_t offset_fsb;
823 xfs_filblks_t count_fsb;
824 xfs_filblks_t numblks_fsb;
825 xfs_fsblock_t firstfsb;
828 xfs_bmbt_irec_t imap;
829 xfs_bmap_free_t free_list;
835 trace_xfs_unwritten_convert(ip, offset, count);
837 offset_fsb = XFS_B_TO_FSBT(mp, offset);
838 count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
839 count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
842 * Reserve enough blocks in this transaction for two complete extent
843 * btree splits. We may be converting the middle part of an unwritten
844 * extent and in this case we will insert two new extents in the btree
845 * each of which could cause a full split.
847 * This reservation amount will be used in the first call to
848 * xfs_bmbt_split() to select an AG with enough space to satisfy the
849 * rest of the operation.
851 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
855 * set up a transaction to convert the range of extents
856 * from unwritten to real. Do allocations in a loop until
857 * we have covered the range passed in.
859 * Note that we open code the transaction allocation here
860 * to pass KM_NOFS--we can't risk to recursing back into
861 * the filesystem here as we might be asked to write out
862 * the same inode that we complete here and might deadlock
865 sb_start_intwrite(mp->m_super);
866 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
867 tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
868 error = xfs_trans_reserve(tp, resblks,
869 XFS_WRITE_LOG_RES(mp), 0,
870 XFS_TRANS_PERM_LOG_RES,
871 XFS_WRITE_LOG_COUNT);
873 xfs_trans_cancel(tp, 0);
874 return XFS_ERROR(error);
877 xfs_ilock(ip, XFS_ILOCK_EXCL);
878 xfs_trans_ijoin(tp, ip, 0);
881 * Modify the unwritten extent state of the buffer.
883 xfs_bmap_init(&free_list, &firstfsb);
885 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
886 XFS_BMAPI_CONVERT, &firstfsb,
887 1, &imap, &nimaps, &free_list);
889 goto error_on_bmapi_transaction;
892 * Log the updated inode size as we go. We have to be careful
893 * to only log it up to the actual write offset if it is
894 * halfway into a block.
896 i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
897 if (i_size > offset + count)
898 i_size = offset + count;
900 i_size = xfs_new_eof(ip, i_size);
902 ip->i_d.di_size = i_size;
903 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
906 error = xfs_bmap_finish(&tp, &free_list, &committed);
908 goto error_on_bmapi_transaction;
910 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
911 xfs_iunlock(ip, XFS_ILOCK_EXCL);
913 return XFS_ERROR(error);
915 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
916 return xfs_alert_fsblock_zero(ip, &imap);
918 if ((numblks_fsb = imap.br_blockcount) == 0) {
920 * The numblks_fsb value should always get
921 * smaller, otherwise the loop is stuck.
923 ASSERT(imap.br_blockcount);
926 offset_fsb += numblks_fsb;
927 count_fsb -= numblks_fsb;
928 } while (count_fsb > 0);
932 error_on_bmapi_transaction:
933 xfs_bmap_cancel(&free_list);
934 xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
935 xfs_iunlock(ip, XFS_ILOCK_EXCL);
936 return XFS_ERROR(error);