Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
[linux-drm-fsl-dcu.git] / fs / xfs / xfs_iomap.c
1 /*
2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
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.
8  *
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.
13  *
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
17  */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_log.h"
21 #include "xfs_trans.h"
22 #include "xfs_sb.h"
23 #include "xfs_ag.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"
34 #include "xfs_bmap.h"
35 #include "xfs_rtalloc.h"
36 #include "xfs_error.h"
37 #include "xfs_itable.h"
38 #include "xfs_attr.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
45
46 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
47                                                 << mp->m_writeio_log)
48 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
49
50 STATIC int
51 xfs_iomap_eof_align_last_fsb(
52         xfs_mount_t     *mp,
53         xfs_inode_t     *ip,
54         xfs_extlen_t    extsize,
55         xfs_fileoff_t   *last_fsb)
56 {
57         xfs_fileoff_t   new_last_fsb = 0;
58         xfs_extlen_t    align = 0;
59         int             eof, error;
60
61         if (!XFS_IS_REALTIME_INODE(ip)) {
62                 /*
63                  * Round up the allocation request to a stripe unit
64                  * (m_dalign) boundary if the file size is >= stripe unit
65                  * size, and we are allocating past the allocation eof.
66                  *
67                  * If mounted with the "-o swalloc" option the alignment is
68                  * increased from the strip unit size to the stripe width.
69                  */
70                 if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
71                         align = mp->m_swidth;
72                 else if (mp->m_dalign)
73                         align = mp->m_dalign;
74
75                 if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
76                         new_last_fsb = roundup_64(*last_fsb, align);
77         }
78
79         /*
80          * Always round up the allocation request to an extent boundary
81          * (when file on a real-time subvolume or has di_extsize hint).
82          */
83         if (extsize) {
84                 if (new_last_fsb)
85                         align = roundup_64(new_last_fsb, extsize);
86                 else
87                         align = extsize;
88                 new_last_fsb = roundup_64(*last_fsb, align);
89         }
90
91         if (new_last_fsb) {
92                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
93                 if (error)
94                         return error;
95                 if (eof)
96                         *last_fsb = new_last_fsb;
97         }
98         return 0;
99 }
100
101 STATIC int
102 xfs_alert_fsblock_zero(
103         xfs_inode_t     *ip,
104         xfs_bmbt_irec_t *imap)
105 {
106         xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
107                         "Access to block zero in inode %llu "
108                         "start_block: %llx start_off: %llx "
109                         "blkcnt: %llx extent-state: %x\n",
110                 (unsigned long long)ip->i_ino,
111                 (unsigned long long)imap->br_startblock,
112                 (unsigned long long)imap->br_startoff,
113                 (unsigned long long)imap->br_blockcount,
114                 imap->br_state);
115         return EFSCORRUPTED;
116 }
117
118 int
119 xfs_iomap_write_direct(
120         xfs_inode_t     *ip,
121         xfs_off_t       offset,
122         size_t          count,
123         xfs_bmbt_irec_t *imap,
124         int             nmaps)
125 {
126         xfs_mount_t     *mp = ip->i_mount;
127         xfs_fileoff_t   offset_fsb;
128         xfs_fileoff_t   last_fsb;
129         xfs_filblks_t   count_fsb, resaligned;
130         xfs_fsblock_t   firstfsb;
131         xfs_extlen_t    extsz, temp;
132         int             nimaps;
133         int             bmapi_flag;
134         int             quota_flag;
135         int             rt;
136         xfs_trans_t     *tp;
137         xfs_bmap_free_t free_list;
138         uint            qblocks, resblks, resrtextents;
139         int             committed;
140         int             error;
141
142         error = xfs_qm_dqattach(ip, 0);
143         if (error)
144                 return XFS_ERROR(error);
145
146         rt = XFS_IS_REALTIME_INODE(ip);
147         extsz = xfs_get_extsz_hint(ip);
148
149         offset_fsb = XFS_B_TO_FSBT(mp, offset);
150         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
151         if ((offset + count) > XFS_ISIZE(ip)) {
152                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
153                 if (error)
154                         return XFS_ERROR(error);
155         } else {
156                 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
157                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
158                                         imap->br_blockcount +
159                                         imap->br_startoff);
160         }
161         count_fsb = last_fsb - offset_fsb;
162         ASSERT(count_fsb > 0);
163
164         resaligned = count_fsb;
165         if (unlikely(extsz)) {
166                 if ((temp = do_mod(offset_fsb, extsz)))
167                         resaligned += temp;
168                 if ((temp = do_mod(resaligned, extsz)))
169                         resaligned += extsz - temp;
170         }
171
172         if (unlikely(rt)) {
173                 resrtextents = qblocks = resaligned;
174                 resrtextents /= mp->m_sb.sb_rextsize;
175                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
176                 quota_flag = XFS_QMOPT_RES_RTBLKS;
177         } else {
178                 resrtextents = 0;
179                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
180                 quota_flag = XFS_QMOPT_RES_REGBLKS;
181         }
182
183         /*
184          * Allocate and setup the transaction
185          */
186         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
187         error = xfs_trans_reserve(tp, resblks,
188                         XFS_WRITE_LOG_RES(mp), resrtextents,
189                         XFS_TRANS_PERM_LOG_RES,
190                         XFS_WRITE_LOG_COUNT);
191         /*
192          * Check for running out of space, note: need lock to return
193          */
194         if (error) {
195                 xfs_trans_cancel(tp, 0);
196                 return XFS_ERROR(error);
197         }
198
199         xfs_ilock(ip, XFS_ILOCK_EXCL);
200
201         error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
202         if (error)
203                 goto out_trans_cancel;
204
205         xfs_trans_ijoin(tp, ip, 0);
206
207         bmapi_flag = 0;
208         if (offset < XFS_ISIZE(ip) || extsz)
209                 bmapi_flag |= XFS_BMAPI_PREALLOC;
210
211         /*
212          * From this point onwards we overwrite the imap pointer that the
213          * caller gave to us.
214          */
215         xfs_bmap_init(&free_list, &firstfsb);
216         nimaps = 1;
217         error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
218                                 &firstfsb, 0, imap, &nimaps, &free_list);
219         if (error)
220                 goto out_bmap_cancel;
221
222         /*
223          * Complete the transaction
224          */
225         error = xfs_bmap_finish(&tp, &free_list, &committed);
226         if (error)
227                 goto out_bmap_cancel;
228         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
229         if (error)
230                 goto out_unlock;
231
232         /*
233          * Copy any maps to caller's array and return any error.
234          */
235         if (nimaps == 0) {
236                 error = XFS_ERROR(ENOSPC);
237                 goto out_unlock;
238         }
239
240         if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
241                 error = xfs_alert_fsblock_zero(ip, imap);
242
243 out_unlock:
244         xfs_iunlock(ip, XFS_ILOCK_EXCL);
245         return error;
246
247 out_bmap_cancel:
248         xfs_bmap_cancel(&free_list);
249         xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
250 out_trans_cancel:
251         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
252         goto out_unlock;
253 }
254
255 /*
256  * If the caller is doing a write at the end of the file, then extend the
257  * allocation out to the file system's write iosize.  We clean up any extra
258  * space left over when the file is closed in xfs_inactive().
259  *
260  * If we find we already have delalloc preallocation beyond EOF, don't do more
261  * preallocation as it it not needed.
262  */
263 STATIC int
264 xfs_iomap_eof_want_preallocate(
265         xfs_mount_t     *mp,
266         xfs_inode_t     *ip,
267         xfs_off_t       offset,
268         size_t          count,
269         xfs_bmbt_irec_t *imap,
270         int             nimaps,
271         int             *prealloc)
272 {
273         xfs_fileoff_t   start_fsb;
274         xfs_filblks_t   count_fsb;
275         xfs_fsblock_t   firstblock;
276         int             n, error, imaps;
277         int             found_delalloc = 0;
278
279         *prealloc = 0;
280         if (offset + count <= XFS_ISIZE(ip))
281                 return 0;
282
283         /*
284          * If there are any real blocks past eof, then don't
285          * do any speculative allocation.
286          */
287         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
288         count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
289         while (count_fsb > 0) {
290                 imaps = nimaps;
291                 firstblock = NULLFSBLOCK;
292                 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
293                                        0);
294                 if (error)
295                         return error;
296                 for (n = 0; n < imaps; n++) {
297                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
298                             (imap[n].br_startblock != DELAYSTARTBLOCK))
299                                 return 0;
300                         start_fsb += imap[n].br_blockcount;
301                         count_fsb -= imap[n].br_blockcount;
302
303                         if (imap[n].br_startblock == DELAYSTARTBLOCK)
304                                 found_delalloc = 1;
305                 }
306         }
307         if (!found_delalloc)
308                 *prealloc = 1;
309         return 0;
310 }
311
312 /*
313  * If we don't have a user specified preallocation size, dynamically increase
314  * the preallocation size as the size of the file grows. Cap the maximum size
315  * at a single extent or less if the filesystem is near full. The closer the
316  * filesystem is to full, the smaller the maximum prealocation.
317  */
318 STATIC xfs_fsblock_t
319 xfs_iomap_prealloc_size(
320         struct xfs_mount        *mp,
321         struct xfs_inode        *ip)
322 {
323         xfs_fsblock_t           alloc_blocks = 0;
324
325         if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
326                 int shift = 0;
327                 int64_t freesp;
328
329                 /*
330                  * rounddown_pow_of_two() returns an undefined result
331                  * if we pass in alloc_blocks = 0. Hence the "+ 1" to
332                  * ensure we always pass in a non-zero value.
333                  */
334                 alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
335                 alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
336                                         rounddown_pow_of_two(alloc_blocks));
337
338                 xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
339                 freesp = mp->m_sb.sb_fdblocks;
340                 if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
341                         shift = 2;
342                         if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
343                                 shift++;
344                         if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
345                                 shift++;
346                         if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
347                                 shift++;
348                         if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
349                                 shift++;
350                 }
351                 if (shift)
352                         alloc_blocks >>= shift;
353         }
354
355         if (alloc_blocks < mp->m_writeio_blocks)
356                 alloc_blocks = mp->m_writeio_blocks;
357
358         return alloc_blocks;
359 }
360
361 int
362 xfs_iomap_write_delay(
363         xfs_inode_t     *ip,
364         xfs_off_t       offset,
365         size_t          count,
366         xfs_bmbt_irec_t *ret_imap)
367 {
368         xfs_mount_t     *mp = ip->i_mount;
369         xfs_fileoff_t   offset_fsb;
370         xfs_fileoff_t   last_fsb;
371         xfs_off_t       aligned_offset;
372         xfs_fileoff_t   ioalign;
373         xfs_extlen_t    extsz;
374         int             nimaps;
375         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
376         int             prealloc, flushed = 0;
377         int             error;
378
379         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
380
381         /*
382          * Make sure that the dquots are there. This doesn't hold
383          * the ilock across a disk read.
384          */
385         error = xfs_qm_dqattach_locked(ip, 0);
386         if (error)
387                 return XFS_ERROR(error);
388
389         extsz = xfs_get_extsz_hint(ip);
390         offset_fsb = XFS_B_TO_FSBT(mp, offset);
391
392
393         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
394                                 imap, XFS_WRITE_IMAPS, &prealloc);
395         if (error)
396                 return error;
397
398 retry:
399         if (prealloc) {
400                 xfs_fsblock_t   alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
401
402                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
403                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
404                 last_fsb = ioalign + alloc_blocks;
405         } else {
406                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
407         }
408
409         if (prealloc || extsz) {
410                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
411                 if (error)
412                         return error;
413         }
414
415         /*
416          * Make sure preallocation does not create extents beyond the range we
417          * actually support in this filesystem.
418          */
419         if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
420                 last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
421
422         ASSERT(last_fsb > offset_fsb);
423
424         nimaps = XFS_WRITE_IMAPS;
425         error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
426                                 imap, &nimaps, XFS_BMAPI_ENTIRE);
427         switch (error) {
428         case 0:
429         case ENOSPC:
430         case EDQUOT:
431                 break;
432         default:
433                 return XFS_ERROR(error);
434         }
435
436         /*
437          * If bmapi returned us nothing, we got either ENOSPC or EDQUOT.  For
438          * ENOSPC, * flush all other inodes with delalloc blocks to free up
439          * some of the excess reserved metadata space. For both cases, retry
440          * without EOF preallocation.
441          */
442         if (nimaps == 0) {
443                 trace_xfs_delalloc_enospc(ip, offset, count);
444                 if (flushed)
445                         return XFS_ERROR(error ? error : ENOSPC);
446
447                 if (error == ENOSPC) {
448                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
449                         xfs_flush_inodes(ip);
450                         xfs_ilock(ip, XFS_ILOCK_EXCL);
451                 }
452
453                 flushed = 1;
454                 error = 0;
455                 prealloc = 0;
456                 goto retry;
457         }
458
459         if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
460                 return xfs_alert_fsblock_zero(ip, &imap[0]);
461
462         *ret_imap = imap[0];
463         return 0;
464 }
465
466 /*
467  * Pass in a delayed allocate extent, convert it to real extents;
468  * return to the caller the extent we create which maps on top of
469  * the originating callers request.
470  *
471  * Called without a lock on the inode.
472  *
473  * We no longer bother to look at the incoming map - all we have to
474  * guarantee is that whatever we allocate fills the required range.
475  */
476 int
477 xfs_iomap_write_allocate(
478         xfs_inode_t     *ip,
479         xfs_off_t       offset,
480         size_t          count,
481         xfs_bmbt_irec_t *imap)
482 {
483         xfs_mount_t     *mp = ip->i_mount;
484         xfs_fileoff_t   offset_fsb, last_block;
485         xfs_fileoff_t   end_fsb, map_start_fsb;
486         xfs_fsblock_t   first_block;
487         xfs_bmap_free_t free_list;
488         xfs_filblks_t   count_fsb;
489         xfs_trans_t     *tp;
490         int             nimaps, committed;
491         int             error = 0;
492         int             nres;
493
494         /*
495          * Make sure that the dquots are there.
496          */
497         error = xfs_qm_dqattach(ip, 0);
498         if (error)
499                 return XFS_ERROR(error);
500
501         offset_fsb = XFS_B_TO_FSBT(mp, offset);
502         count_fsb = imap->br_blockcount;
503         map_start_fsb = imap->br_startoff;
504
505         XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
506
507         while (count_fsb != 0) {
508                 /*
509                  * Set up a transaction with which to allocate the
510                  * backing store for the file.  Do allocations in a
511                  * loop until we get some space in the range we are
512                  * interested in.  The other space that might be allocated
513                  * is in the delayed allocation extent on which we sit
514                  * but before our buffer starts.
515                  */
516
517                 nimaps = 0;
518                 while (nimaps == 0) {
519                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
520                         tp->t_flags |= XFS_TRANS_RESERVE;
521                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
522                         error = xfs_trans_reserve(tp, nres,
523                                         XFS_WRITE_LOG_RES(mp),
524                                         0, XFS_TRANS_PERM_LOG_RES,
525                                         XFS_WRITE_LOG_COUNT);
526                         if (error) {
527                                 xfs_trans_cancel(tp, 0);
528                                 return XFS_ERROR(error);
529                         }
530                         xfs_ilock(ip, XFS_ILOCK_EXCL);
531                         xfs_trans_ijoin(tp, ip, 0);
532
533                         xfs_bmap_init(&free_list, &first_block);
534
535                         /*
536                          * it is possible that the extents have changed since
537                          * we did the read call as we dropped the ilock for a
538                          * while. We have to be careful about truncates or hole
539                          * punchs here - we are not allowed to allocate
540                          * non-delalloc blocks here.
541                          *
542                          * The only protection against truncation is the pages
543                          * for the range we are being asked to convert are
544                          * locked and hence a truncate will block on them
545                          * first.
546                          *
547                          * As a result, if we go beyond the range we really
548                          * need and hit an delalloc extent boundary followed by
549                          * a hole while we have excess blocks in the map, we
550                          * will fill the hole incorrectly and overrun the
551                          * transaction reservation.
552                          *
553                          * Using a single map prevents this as we are forced to
554                          * check each map we look for overlap with the desired
555                          * range and abort as soon as we find it. Also, given
556                          * that we only return a single map, having one beyond
557                          * what we can return is probably a bit silly.
558                          *
559                          * We also need to check that we don't go beyond EOF;
560                          * this is a truncate optimisation as a truncate sets
561                          * the new file size before block on the pages we
562                          * currently have locked under writeback. Because they
563                          * are about to be tossed, we don't need to write them
564                          * back....
565                          */
566                         nimaps = 1;
567                         end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
568                         error = xfs_bmap_last_offset(NULL, ip, &last_block,
569                                                         XFS_DATA_FORK);
570                         if (error)
571                                 goto trans_cancel;
572
573                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
574                         if ((map_start_fsb + count_fsb) > last_block) {
575                                 count_fsb = last_block - map_start_fsb;
576                                 if (count_fsb == 0) {
577                                         error = EAGAIN;
578                                         goto trans_cancel;
579                                 }
580                         }
581
582                         /*
583                          * From this point onwards we overwrite the imap
584                          * pointer that the caller gave to us.
585                          */
586                         error = xfs_bmapi_write(tp, ip, map_start_fsb,
587                                                 count_fsb, 0, &first_block, 1,
588                                                 imap, &nimaps, &free_list);
589                         if (error)
590                                 goto trans_cancel;
591
592                         error = xfs_bmap_finish(&tp, &free_list, &committed);
593                         if (error)
594                                 goto trans_cancel;
595
596                         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
597                         if (error)
598                                 goto error0;
599
600                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
601                 }
602
603                 /*
604                  * See if we were able to allocate an extent that
605                  * covers at least part of the callers request
606                  */
607                 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
608                         return xfs_alert_fsblock_zero(ip, imap);
609
610                 if ((offset_fsb >= imap->br_startoff) &&
611                     (offset_fsb < (imap->br_startoff +
612                                    imap->br_blockcount))) {
613                         XFS_STATS_INC(xs_xstrat_quick);
614                         return 0;
615                 }
616
617                 /*
618                  * So far we have not mapped the requested part of the
619                  * file, just surrounding data, try again.
620                  */
621                 count_fsb -= imap->br_blockcount;
622                 map_start_fsb = imap->br_startoff + imap->br_blockcount;
623         }
624
625 trans_cancel:
626         xfs_bmap_cancel(&free_list);
627         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
628 error0:
629         xfs_iunlock(ip, XFS_ILOCK_EXCL);
630         return XFS_ERROR(error);
631 }
632
633 int
634 xfs_iomap_write_unwritten(
635         xfs_inode_t     *ip,
636         xfs_off_t       offset,
637         size_t          count)
638 {
639         xfs_mount_t     *mp = ip->i_mount;
640         xfs_fileoff_t   offset_fsb;
641         xfs_filblks_t   count_fsb;
642         xfs_filblks_t   numblks_fsb;
643         xfs_fsblock_t   firstfsb;
644         int             nimaps;
645         xfs_trans_t     *tp;
646         xfs_bmbt_irec_t imap;
647         xfs_bmap_free_t free_list;
648         xfs_fsize_t     i_size;
649         uint            resblks;
650         int             committed;
651         int             error;
652
653         trace_xfs_unwritten_convert(ip, offset, count);
654
655         offset_fsb = XFS_B_TO_FSBT(mp, offset);
656         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
657         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
658
659         /*
660          * Reserve enough blocks in this transaction for two complete extent
661          * btree splits.  We may be converting the middle part of an unwritten
662          * extent and in this case we will insert two new extents in the btree
663          * each of which could cause a full split.
664          *
665          * This reservation amount will be used in the first call to
666          * xfs_bmbt_split() to select an AG with enough space to satisfy the
667          * rest of the operation.
668          */
669         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
670
671         do {
672                 /*
673                  * set up a transaction to convert the range of extents
674                  * from unwritten to real. Do allocations in a loop until
675                  * we have covered the range passed in.
676                  *
677                  * Note that we open code the transaction allocation here
678                  * to pass KM_NOFS--we can't risk to recursing back into
679                  * the filesystem here as we might be asked to write out
680                  * the same inode that we complete here and might deadlock
681                  * on the iolock.
682                  */
683                 sb_start_intwrite(mp->m_super);
684                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
685                 tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
686                 error = xfs_trans_reserve(tp, resblks,
687                                 XFS_WRITE_LOG_RES(mp), 0,
688                                 XFS_TRANS_PERM_LOG_RES,
689                                 XFS_WRITE_LOG_COUNT);
690                 if (error) {
691                         xfs_trans_cancel(tp, 0);
692                         return XFS_ERROR(error);
693                 }
694
695                 xfs_ilock(ip, XFS_ILOCK_EXCL);
696                 xfs_trans_ijoin(tp, ip, 0);
697
698                 /*
699                  * Modify the unwritten extent state of the buffer.
700                  */
701                 xfs_bmap_init(&free_list, &firstfsb);
702                 nimaps = 1;
703                 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
704                                   XFS_BMAPI_CONVERT, &firstfsb,
705                                   1, &imap, &nimaps, &free_list);
706                 if (error)
707                         goto error_on_bmapi_transaction;
708
709                 /*
710                  * Log the updated inode size as we go.  We have to be careful
711                  * to only log it up to the actual write offset if it is
712                  * halfway into a block.
713                  */
714                 i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
715                 if (i_size > offset + count)
716                         i_size = offset + count;
717
718                 i_size = xfs_new_eof(ip, i_size);
719                 if (i_size) {
720                         ip->i_d.di_size = i_size;
721                         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
722                 }
723
724                 error = xfs_bmap_finish(&tp, &free_list, &committed);
725                 if (error)
726                         goto error_on_bmapi_transaction;
727
728                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
729                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
730                 if (error)
731                         return XFS_ERROR(error);
732
733                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
734                         return xfs_alert_fsblock_zero(ip, &imap);
735
736                 if ((numblks_fsb = imap.br_blockcount) == 0) {
737                         /*
738                          * The numblks_fsb value should always get
739                          * smaller, otherwise the loop is stuck.
740                          */
741                         ASSERT(imap.br_blockcount);
742                         break;
743                 }
744                 offset_fsb += numblks_fsb;
745                 count_fsb -= numblks_fsb;
746         } while (count_fsb > 0);
747
748         return 0;
749
750 error_on_bmapi_transaction:
751         xfs_bmap_cancel(&free_list);
752         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
753         xfs_iunlock(ip, XFS_ILOCK_EXCL);
754         return XFS_ERROR(error);
755 }