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TOMOYO Linux Cross Reference
Linux/fs/xfs/xfs_iomap.c

Version: ~ [ linux-5.2-rc1 ] ~ [ linux-5.1.2 ] ~ [ linux-5.0.16 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.43 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.119 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.176 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.179 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.139 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.67 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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_shared.h"
 21 #include "xfs_format.h"
 22 #include "xfs_log_format.h"
 23 #include "xfs_trans_resv.h"
 24 #include "xfs_mount.h"
 25 #include "xfs_inode.h"
 26 #include "xfs_btree.h"
 27 #include "xfs_bmap_btree.h"
 28 #include "xfs_bmap.h"
 29 #include "xfs_bmap_util.h"
 30 #include "xfs_error.h"
 31 #include "xfs_trans.h"
 32 #include "xfs_trans_space.h"
 33 #include "xfs_iomap.h"
 34 #include "xfs_trace.h"
 35 #include "xfs_icache.h"
 36 #include "xfs_quota.h"
 37 #include "xfs_dquot_item.h"
 38 #include "xfs_dquot.h"
 39 
 40 
 41 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
 42                                                 << mp->m_writeio_log)
 43 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
 44 
 45 STATIC int
 46 xfs_iomap_eof_align_last_fsb(
 47         xfs_mount_t     *mp,
 48         xfs_inode_t     *ip,
 49         xfs_extlen_t    extsize,
 50         xfs_fileoff_t   *last_fsb)
 51 {
 52         xfs_extlen_t    align = 0;
 53         int             eof, error;
 54 
 55         if (!XFS_IS_REALTIME_INODE(ip)) {
 56                 /*
 57                  * Round up the allocation request to a stripe unit
 58                  * (m_dalign) boundary if the file size is >= stripe unit
 59                  * size, and we are allocating past the allocation eof.
 60                  *
 61                  * If mounted with the "-o swalloc" option the alignment is
 62                  * increased from the strip unit size to the stripe width.
 63                  */
 64                 if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
 65                         align = mp->m_swidth;
 66                 else if (mp->m_dalign)
 67                         align = mp->m_dalign;
 68 
 69                 if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align))
 70                         align = 0;
 71         }
 72 
 73         /*
 74          * Always round up the allocation request to an extent boundary
 75          * (when file on a real-time subvolume or has di_extsize hint).
 76          */
 77         if (extsize) {
 78                 if (align)
 79                         align = roundup_64(align, extsize);
 80                 else
 81                         align = extsize;
 82         }
 83 
 84         if (align) {
 85                 xfs_fileoff_t   new_last_fsb = roundup_64(*last_fsb, align);
 86                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 87                 if (error)
 88                         return error;
 89                 if (eof)
 90                         *last_fsb = new_last_fsb;
 91         }
 92         return 0;
 93 }
 94 
 95 STATIC int
 96 xfs_alert_fsblock_zero(
 97         xfs_inode_t     *ip,
 98         xfs_bmbt_irec_t *imap)
 99 {
100         xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
101                         "Access to block zero in inode %llu "
102                         "start_block: %llx start_off: %llx "
103                         "blkcnt: %llx extent-state: %x",
104                 (unsigned long long)ip->i_ino,
105                 (unsigned long long)imap->br_startblock,
106                 (unsigned long long)imap->br_startoff,
107                 (unsigned long long)imap->br_blockcount,
108                 imap->br_state);
109         return -EFSCORRUPTED;
110 }
111 
112 int
113 xfs_iomap_write_direct(
114         xfs_inode_t     *ip,
115         xfs_off_t       offset,
116         size_t          count,
117         xfs_bmbt_irec_t *imap,
118         int             nmaps)
119 {
120         xfs_mount_t     *mp = ip->i_mount;
121         xfs_fileoff_t   offset_fsb;
122         xfs_fileoff_t   last_fsb;
123         xfs_filblks_t   count_fsb, resaligned;
124         xfs_fsblock_t   firstfsb;
125         xfs_extlen_t    extsz, temp;
126         int             nimaps;
127         int             quota_flag;
128         int             rt;
129         xfs_trans_t     *tp;
130         xfs_bmap_free_t free_list;
131         uint            qblocks, resblks, resrtextents;
132         int             error;
133         int             lockmode;
134         int             bmapi_flags = XFS_BMAPI_PREALLOC;
135 
136         rt = XFS_IS_REALTIME_INODE(ip);
137         extsz = xfs_get_extsz_hint(ip);
138         lockmode = XFS_ILOCK_SHARED;    /* locked by caller */
139 
140         ASSERT(xfs_isilocked(ip, lockmode));
141 
142         offset_fsb = XFS_B_TO_FSBT(mp, offset);
143         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
144         if ((offset + count) > XFS_ISIZE(ip)) {
145                 /*
146                  * Assert that the in-core extent list is present since this can
147                  * call xfs_iread_extents() and we only have the ilock shared.
148                  * This should be safe because the lock was held around a bmapi
149                  * call in the caller and we only need it to access the in-core
150                  * list.
151                  */
152                 ASSERT(XFS_IFORK_PTR(ip, XFS_DATA_FORK)->if_flags &
153                                                                 XFS_IFEXTENTS);
154                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
155                 if (error)
156                         goto out_unlock;
157         } else {
158                 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
159                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
160                                         imap->br_blockcount +
161                                         imap->br_startoff);
162         }
163         count_fsb = last_fsb - offset_fsb;
164         ASSERT(count_fsb > 0);
165 
166         resaligned = count_fsb;
167         if (unlikely(extsz)) {
168                 if ((temp = do_mod(offset_fsb, extsz)))
169                         resaligned += temp;
170                 if ((temp = do_mod(resaligned, extsz)))
171                         resaligned += extsz - temp;
172         }
173 
174         if (unlikely(rt)) {
175                 resrtextents = qblocks = resaligned;
176                 resrtextents /= mp->m_sb.sb_rextsize;
177                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
178                 quota_flag = XFS_QMOPT_RES_RTBLKS;
179         } else {
180                 resrtextents = 0;
181                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
182                 quota_flag = XFS_QMOPT_RES_REGBLKS;
183         }
184 
185         /*
186          * Drop the shared lock acquired by the caller, attach the dquot if
187          * necessary and move on to transaction setup.
188          */
189         xfs_iunlock(ip, lockmode);
190         error = xfs_qm_dqattach(ip, 0);
191         if (error)
192                 return error;
193 
194         /*
195          * Allocate and setup the transaction
196          */
197         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
198 
199         /*
200          * For DAX, we do not allocate unwritten extents, but instead we zero
201          * the block before we commit the transaction.  Ideally we'd like to do
202          * this outside the transaction context, but if we commit and then crash
203          * we may not have zeroed the blocks and this will be exposed on
204          * recovery of the allocation. Hence we must zero before commit.
205          *
206          * Further, if we are mapping unwritten extents here, we need to zero
207          * and convert them to written so that we don't need an unwritten extent
208          * callback for DAX. This also means that we need to be able to dip into
209          * the reserve block pool for bmbt block allocation if there is no space
210          * left but we need to do unwritten extent conversion.
211          */
212 
213         if (IS_DAX(VFS_I(ip))) {
214                 bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO;
215                 if (ISUNWRITTEN(imap)) {
216                         tp->t_flags |= XFS_TRANS_RESERVE;
217                         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
218                 }
219         }
220         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
221                                   resblks, resrtextents);
222         /*
223          * Check for running out of space, note: need lock to return
224          */
225         if (error) {
226                 xfs_trans_cancel(tp);
227                 return error;
228         }
229 
230         lockmode = XFS_ILOCK_EXCL;
231         xfs_ilock(ip, lockmode);
232 
233         error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
234         if (error)
235                 goto out_trans_cancel;
236 
237         xfs_trans_ijoin(tp, ip, 0);
238 
239         /*
240          * From this point onwards we overwrite the imap pointer that the
241          * caller gave to us.
242          */
243         xfs_bmap_init(&free_list, &firstfsb);
244         nimaps = 1;
245         error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
246                                 bmapi_flags, &firstfsb, resblks, imap,
247                                 &nimaps, &free_list);
248         if (error)
249                 goto out_bmap_cancel;
250 
251         /*
252          * Complete the transaction
253          */
254         error = xfs_bmap_finish(&tp, &free_list, NULL);
255         if (error)
256                 goto out_bmap_cancel;
257 
258         error = xfs_trans_commit(tp);
259         if (error)
260                 goto out_unlock;
261 
262         /*
263          * Copy any maps to caller's array and return any error.
264          */
265         if (nimaps == 0) {
266                 error = -ENOSPC;
267                 goto out_unlock;
268         }
269 
270         if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
271                 error = xfs_alert_fsblock_zero(ip, imap);
272 
273 out_unlock:
274         xfs_iunlock(ip, lockmode);
275         return error;
276 
277 out_bmap_cancel:
278         xfs_bmap_cancel(&free_list);
279         xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
280 out_trans_cancel:
281         xfs_trans_cancel(tp);
282         goto out_unlock;
283 }
284 
285 /*
286  * If the caller is doing a write at the end of the file, then extend the
287  * allocation out to the file system's write iosize.  We clean up any extra
288  * space left over when the file is closed in xfs_inactive().
289  *
290  * If we find we already have delalloc preallocation beyond EOF, don't do more
291  * preallocation as it it not needed.
292  */
293 STATIC int
294 xfs_iomap_eof_want_preallocate(
295         xfs_mount_t     *mp,
296         xfs_inode_t     *ip,
297         xfs_off_t       offset,
298         size_t          count,
299         xfs_bmbt_irec_t *imap,
300         int             nimaps,
301         int             *prealloc)
302 {
303         xfs_fileoff_t   start_fsb;
304         xfs_filblks_t   count_fsb;
305         int             n, error, imaps;
306         int             found_delalloc = 0;
307 
308         *prealloc = 0;
309         if (offset + count <= XFS_ISIZE(ip))
310                 return 0;
311 
312         /*
313          * If the file is smaller than the minimum prealloc and we are using
314          * dynamic preallocation, don't do any preallocation at all as it is
315          * likely this is the only write to the file that is going to be done.
316          */
317         if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
318             XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
319                 return 0;
320 
321         /*
322          * If there are any real blocks past eof, then don't
323          * do any speculative allocation.
324          */
325         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
326         count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
327         while (count_fsb > 0) {
328                 imaps = nimaps;
329                 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
330                                        0);
331                 if (error)
332                         return error;
333                 for (n = 0; n < imaps; n++) {
334                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
335                             (imap[n].br_startblock != DELAYSTARTBLOCK))
336                                 return 0;
337                         start_fsb += imap[n].br_blockcount;
338                         count_fsb -= imap[n].br_blockcount;
339 
340                         if (imap[n].br_startblock == DELAYSTARTBLOCK)
341                                 found_delalloc = 1;
342                 }
343         }
344         if (!found_delalloc)
345                 *prealloc = 1;
346         return 0;
347 }
348 
349 /*
350  * Determine the initial size of the preallocation. We are beyond the current
351  * EOF here, but we need to take into account whether this is a sparse write or
352  * an extending write when determining the preallocation size.  Hence we need to
353  * look up the extent that ends at the current write offset and use the result
354  * to determine the preallocation size.
355  *
356  * If the extent is a hole, then preallocation is essentially disabled.
357  * Otherwise we take the size of the preceeding data extent as the basis for the
358  * preallocation size. If the size of the extent is greater than half the
359  * maximum extent length, then use the current offset as the basis. This ensures
360  * that for large files the preallocation size always extends to MAXEXTLEN
361  * rather than falling short due to things like stripe unit/width alignment of
362  * real extents.
363  */
364 STATIC xfs_fsblock_t
365 xfs_iomap_eof_prealloc_initial_size(
366         struct xfs_mount        *mp,
367         struct xfs_inode        *ip,
368         xfs_off_t               offset,
369         xfs_bmbt_irec_t         *imap,
370         int                     nimaps)
371 {
372         xfs_fileoff_t   start_fsb;
373         int             imaps = 1;
374         int             error;
375 
376         ASSERT(nimaps >= imaps);
377 
378         /* if we are using a specific prealloc size, return now */
379         if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
380                 return 0;
381 
382         /* If the file is small, then use the minimum prealloc */
383         if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
384                 return 0;
385 
386         /*
387          * As we write multiple pages, the offset will always align to the
388          * start of a page and hence point to a hole at EOF. i.e. if the size is
389          * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
390          * will return FSB 1. Hence if there are blocks in the file, we want to
391          * point to the block prior to the EOF block and not the hole that maps
392          * directly at @offset.
393          */
394         start_fsb = XFS_B_TO_FSB(mp, offset);
395         if (start_fsb)
396                 start_fsb--;
397         error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
398         if (error)
399                 return 0;
400 
401         ASSERT(imaps == 1);
402         if (imap[0].br_startblock == HOLESTARTBLOCK)
403                 return 0;
404         if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
405                 return imap[0].br_blockcount << 1;
406         return XFS_B_TO_FSB(mp, offset);
407 }
408 
409 STATIC bool
410 xfs_quota_need_throttle(
411         struct xfs_inode *ip,
412         int type,
413         xfs_fsblock_t alloc_blocks)
414 {
415         struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
416 
417         if (!dq || !xfs_this_quota_on(ip->i_mount, type))
418                 return false;
419 
420         /* no hi watermark, no throttle */
421         if (!dq->q_prealloc_hi_wmark)
422                 return false;
423 
424         /* under the lo watermark, no throttle */
425         if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark)
426                 return false;
427 
428         return true;
429 }
430 
431 STATIC void
432 xfs_quota_calc_throttle(
433         struct xfs_inode *ip,
434         int type,
435         xfs_fsblock_t *qblocks,
436         int *qshift,
437         int64_t *qfreesp)
438 {
439         int64_t freesp;
440         int shift = 0;
441         struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
442 
443         /* no dq, or over hi wmark, squash the prealloc completely */
444         if (!dq || dq->q_res_bcount >= dq->q_prealloc_hi_wmark) {
445                 *qblocks = 0;
446                 *qfreesp = 0;
447                 return;
448         }
449 
450         freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount;
451         if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) {
452                 shift = 2;
453                 if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT])
454                         shift += 2;
455                 if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT])
456                         shift += 2;
457         }
458 
459         if (freesp < *qfreesp)
460                 *qfreesp = freesp;
461 
462         /* only overwrite the throttle values if we are more aggressive */
463         if ((freesp >> shift) < (*qblocks >> *qshift)) {
464                 *qblocks = freesp;
465                 *qshift = shift;
466         }
467 }
468 
469 /*
470  * If we don't have a user specified preallocation size, dynamically increase
471  * the preallocation size as the size of the file grows. Cap the maximum size
472  * at a single extent or less if the filesystem is near full. The closer the
473  * filesystem is to full, the smaller the maximum prealocation.
474  */
475 STATIC xfs_fsblock_t
476 xfs_iomap_prealloc_size(
477         struct xfs_mount        *mp,
478         struct xfs_inode        *ip,
479         xfs_off_t               offset,
480         struct xfs_bmbt_irec    *imap,
481         int                     nimaps)
482 {
483         xfs_fsblock_t           alloc_blocks = 0;
484         int                     shift = 0;
485         int64_t                 freesp;
486         xfs_fsblock_t           qblocks;
487         int                     qshift = 0;
488 
489         alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
490                                                            imap, nimaps);
491         if (!alloc_blocks)
492                 goto check_writeio;
493         qblocks = alloc_blocks;
494 
495         /*
496          * MAXEXTLEN is not a power of two value but we round the prealloc down
497          * to the nearest power of two value after throttling. To prevent the
498          * round down from unconditionally reducing the maximum supported prealloc
499          * size, we round up first, apply appropriate throttling, round down and
500          * cap the value to MAXEXTLEN.
501          */
502         alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
503                                        alloc_blocks);
504 
505         freesp = percpu_counter_read_positive(&mp->m_fdblocks);
506         if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
507                 shift = 2;
508                 if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
509                         shift++;
510                 if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
511                         shift++;
512                 if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
513                         shift++;
514                 if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
515                         shift++;
516         }
517 
518         /*
519          * Check each quota to cap the prealloc size, provide a shift value to
520          * throttle with and adjust amount of available space.
521          */
522         if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
523                 xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift,
524                                         &freesp);
525         if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
526                 xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift,
527                                         &freesp);
528         if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
529                 xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift,
530                                         &freesp);
531 
532         /*
533          * The final prealloc size is set to the minimum of free space available
534          * in each of the quotas and the overall filesystem.
535          *
536          * The shift throttle value is set to the maximum value as determined by
537          * the global low free space values and per-quota low free space values.
538          */
539         alloc_blocks = MIN(alloc_blocks, qblocks);
540         shift = MAX(shift, qshift);
541 
542         if (shift)
543                 alloc_blocks >>= shift;
544         /*
545          * rounddown_pow_of_two() returns an undefined result if we pass in
546          * alloc_blocks = 0.
547          */
548         if (alloc_blocks)
549                 alloc_blocks = rounddown_pow_of_two(alloc_blocks);
550         if (alloc_blocks > MAXEXTLEN)
551                 alloc_blocks = MAXEXTLEN;
552 
553         /*
554          * If we are still trying to allocate more space than is
555          * available, squash the prealloc hard. This can happen if we
556          * have a large file on a small filesystem and the above
557          * lowspace thresholds are smaller than MAXEXTLEN.
558          */
559         while (alloc_blocks && alloc_blocks >= freesp)
560                 alloc_blocks >>= 4;
561 
562 check_writeio:
563         if (alloc_blocks < mp->m_writeio_blocks)
564                 alloc_blocks = mp->m_writeio_blocks;
565 
566         trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
567                                       mp->m_writeio_blocks);
568 
569         return alloc_blocks;
570 }
571 
572 int
573 xfs_iomap_write_delay(
574         xfs_inode_t     *ip,
575         xfs_off_t       offset,
576         size_t          count,
577         xfs_bmbt_irec_t *ret_imap)
578 {
579         xfs_mount_t     *mp = ip->i_mount;
580         xfs_fileoff_t   offset_fsb;
581         xfs_fileoff_t   last_fsb;
582         xfs_off_t       aligned_offset;
583         xfs_fileoff_t   ioalign;
584         xfs_extlen_t    extsz;
585         int             nimaps;
586         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
587         int             prealloc;
588         int             error;
589 
590         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
591 
592         /*
593          * Make sure that the dquots are there. This doesn't hold
594          * the ilock across a disk read.
595          */
596         error = xfs_qm_dqattach_locked(ip, 0);
597         if (error)
598                 return error;
599 
600         extsz = xfs_get_extsz_hint(ip);
601         offset_fsb = XFS_B_TO_FSBT(mp, offset);
602 
603         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
604                                 imap, XFS_WRITE_IMAPS, &prealloc);
605         if (error)
606                 return error;
607 
608 retry:
609         if (prealloc) {
610                 xfs_fsblock_t   alloc_blocks;
611 
612                 alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
613                                                        XFS_WRITE_IMAPS);
614 
615                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
616                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
617                 last_fsb = ioalign + alloc_blocks;
618         } else {
619                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
620         }
621 
622         if (prealloc || extsz) {
623                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
624                 if (error)
625                         return error;
626         }
627 
628         /*
629          * Make sure preallocation does not create extents beyond the range we
630          * actually support in this filesystem.
631          */
632         if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
633                 last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
634 
635         ASSERT(last_fsb > offset_fsb);
636 
637         nimaps = XFS_WRITE_IMAPS;
638         error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
639                                 imap, &nimaps, XFS_BMAPI_ENTIRE);
640         switch (error) {
641         case 0:
642         case -ENOSPC:
643         case -EDQUOT:
644                 break;
645         default:
646                 return error;
647         }
648 
649         /*
650          * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
651          * without EOF preallocation.
652          */
653         if (nimaps == 0) {
654                 trace_xfs_delalloc_enospc(ip, offset, count);
655                 if (prealloc) {
656                         prealloc = 0;
657                         error = 0;
658                         goto retry;
659                 }
660                 return error ? error : -ENOSPC;
661         }
662 
663         if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
664                 return xfs_alert_fsblock_zero(ip, &imap[0]);
665 
666         /*
667          * Tag the inode as speculatively preallocated so we can reclaim this
668          * space on demand, if necessary.
669          */
670         if (prealloc)
671                 xfs_inode_set_eofblocks_tag(ip);
672 
673         *ret_imap = imap[0];
674         return 0;
675 }
676 
677 /*
678  * Pass in a delayed allocate extent, convert it to real extents;
679  * return to the caller the extent we create which maps on top of
680  * the originating callers request.
681  *
682  * Called without a lock on the inode.
683  *
684  * We no longer bother to look at the incoming map - all we have to
685  * guarantee is that whatever we allocate fills the required range.
686  */
687 int
688 xfs_iomap_write_allocate(
689         xfs_inode_t     *ip,
690         xfs_off_t       offset,
691         xfs_bmbt_irec_t *imap)
692 {
693         xfs_mount_t     *mp = ip->i_mount;
694         xfs_fileoff_t   offset_fsb, last_block;
695         xfs_fileoff_t   end_fsb, map_start_fsb;
696         xfs_fsblock_t   first_block;
697         xfs_bmap_free_t free_list;
698         xfs_filblks_t   count_fsb;
699         xfs_trans_t     *tp;
700         int             nimaps;
701         int             error = 0;
702         int             nres;
703 
704         /*
705          * Make sure that the dquots are there.
706          */
707         error = xfs_qm_dqattach(ip, 0);
708         if (error)
709                 return error;
710 
711         offset_fsb = XFS_B_TO_FSBT(mp, offset);
712         count_fsb = imap->br_blockcount;
713         map_start_fsb = imap->br_startoff;
714 
715         XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
716 
717         while (count_fsb != 0) {
718                 /*
719                  * Set up a transaction with which to allocate the
720                  * backing store for the file.  Do allocations in a
721                  * loop until we get some space in the range we are
722                  * interested in.  The other space that might be allocated
723                  * is in the delayed allocation extent on which we sit
724                  * but before our buffer starts.
725                  */
726 
727                 nimaps = 0;
728                 while (nimaps == 0) {
729                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
730                         tp->t_flags |= XFS_TRANS_RESERVE;
731                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
732                         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
733                                                   nres, 0);
734                         if (error) {
735                                 xfs_trans_cancel(tp);
736                                 return error;
737                         }
738                         xfs_ilock(ip, XFS_ILOCK_EXCL);
739                         xfs_trans_ijoin(tp, ip, 0);
740 
741                         xfs_bmap_init(&free_list, &first_block);
742 
743                         /*
744                          * it is possible that the extents have changed since
745                          * we did the read call as we dropped the ilock for a
746                          * while. We have to be careful about truncates or hole
747                          * punchs here - we are not allowed to allocate
748                          * non-delalloc blocks here.
749                          *
750                          * The only protection against truncation is the pages
751                          * for the range we are being asked to convert are
752                          * locked and hence a truncate will block on them
753                          * first.
754                          *
755                          * As a result, if we go beyond the range we really
756                          * need and hit an delalloc extent boundary followed by
757                          * a hole while we have excess blocks in the map, we
758                          * will fill the hole incorrectly and overrun the
759                          * transaction reservation.
760                          *
761                          * Using a single map prevents this as we are forced to
762                          * check each map we look for overlap with the desired
763                          * range and abort as soon as we find it. Also, given
764                          * that we only return a single map, having one beyond
765                          * what we can return is probably a bit silly.
766                          *
767                          * We also need to check that we don't go beyond EOF;
768                          * this is a truncate optimisation as a truncate sets
769                          * the new file size before block on the pages we
770                          * currently have locked under writeback. Because they
771                          * are about to be tossed, we don't need to write them
772                          * back....
773                          */
774                         nimaps = 1;
775                         end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
776                         error = xfs_bmap_last_offset(ip, &last_block,
777                                                         XFS_DATA_FORK);
778                         if (error)
779                                 goto trans_cancel;
780 
781                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
782                         if ((map_start_fsb + count_fsb) > last_block) {
783                                 count_fsb = last_block - map_start_fsb;
784                                 if (count_fsb == 0) {
785                                         error = -EAGAIN;
786                                         goto trans_cancel;
787                                 }
788                         }
789 
790                         /*
791                          * From this point onwards we overwrite the imap
792                          * pointer that the caller gave to us.
793                          */
794                         error = xfs_bmapi_write(tp, ip, map_start_fsb,
795                                                 count_fsb, 0, &first_block,
796                                                 nres, imap, &nimaps,
797                                                 &free_list);
798                         if (error)
799                                 goto trans_cancel;
800 
801                         error = xfs_bmap_finish(&tp, &free_list, NULL);
802                         if (error)
803                                 goto trans_cancel;
804 
805                         error = xfs_trans_commit(tp);
806                         if (error)
807                                 goto error0;
808 
809                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
810                 }
811 
812                 /*
813                  * See if we were able to allocate an extent that
814                  * covers at least part of the callers request
815                  */
816                 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
817                         return xfs_alert_fsblock_zero(ip, imap);
818 
819                 if ((offset_fsb >= imap->br_startoff) &&
820                     (offset_fsb < (imap->br_startoff +
821                                    imap->br_blockcount))) {
822                         XFS_STATS_INC(mp, xs_xstrat_quick);
823                         return 0;
824                 }
825 
826                 /*
827                  * So far we have not mapped the requested part of the
828                  * file, just surrounding data, try again.
829                  */
830                 count_fsb -= imap->br_blockcount;
831                 map_start_fsb = imap->br_startoff + imap->br_blockcount;
832         }
833 
834 trans_cancel:
835         xfs_bmap_cancel(&free_list);
836         xfs_trans_cancel(tp);
837 error0:
838         xfs_iunlock(ip, XFS_ILOCK_EXCL);
839         return error;
840 }
841 
842 int
843 xfs_iomap_write_unwritten(
844         xfs_inode_t     *ip,
845         xfs_off_t       offset,
846         xfs_off_t       count)
847 {
848         xfs_mount_t     *mp = ip->i_mount;
849         xfs_fileoff_t   offset_fsb;
850         xfs_filblks_t   count_fsb;
851         xfs_filblks_t   numblks_fsb;
852         xfs_fsblock_t   firstfsb;
853         int             nimaps;
854         xfs_trans_t     *tp;
855         xfs_bmbt_irec_t imap;
856         xfs_bmap_free_t free_list;
857         xfs_fsize_t     i_size;
858         uint            resblks;
859         int             error;
860 
861         trace_xfs_unwritten_convert(ip, offset, count);
862 
863         offset_fsb = XFS_B_TO_FSBT(mp, offset);
864         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
865         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
866 
867         /*
868          * Reserve enough blocks in this transaction for two complete extent
869          * btree splits.  We may be converting the middle part of an unwritten
870          * extent and in this case we will insert two new extents in the btree
871          * each of which could cause a full split.
872          *
873          * This reservation amount will be used in the first call to
874          * xfs_bmbt_split() to select an AG with enough space to satisfy the
875          * rest of the operation.
876          */
877         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
878 
879         do {
880                 /*
881                  * set up a transaction to convert the range of extents
882                  * from unwritten to real. Do allocations in a loop until
883                  * we have covered the range passed in.
884                  *
885                  * Note that we open code the transaction allocation here
886                  * to pass KM_NOFS--we can't risk to recursing back into
887                  * the filesystem here as we might be asked to write out
888                  * the same inode that we complete here and might deadlock
889                  * on the iolock.
890                  */
891                 sb_start_intwrite(mp->m_super);
892                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
893                 tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
894                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
895                                           resblks, 0);
896                 if (error) {
897                         xfs_trans_cancel(tp);
898                         return error;
899                 }
900 
901                 xfs_ilock(ip, XFS_ILOCK_EXCL);
902                 xfs_trans_ijoin(tp, ip, 0);
903 
904                 /*
905                  * Modify the unwritten extent state of the buffer.
906                  */
907                 xfs_bmap_init(&free_list, &firstfsb);
908                 nimaps = 1;
909                 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
910                                         XFS_BMAPI_CONVERT, &firstfsb, resblks,
911                                         &imap, &nimaps, &free_list);
912                 if (error)
913                         goto error_on_bmapi_transaction;
914 
915                 /*
916                  * Log the updated inode size as we go.  We have to be careful
917                  * to only log it up to the actual write offset if it is
918                  * halfway into a block.
919                  */
920                 i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
921                 if (i_size > offset + count)
922                         i_size = offset + count;
923 
924                 i_size = xfs_new_eof(ip, i_size);
925                 if (i_size) {
926                         ip->i_d.di_size = i_size;
927                         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
928                 }
929 
930                 error = xfs_bmap_finish(&tp, &free_list, NULL);
931                 if (error)
932                         goto error_on_bmapi_transaction;
933 
934                 error = xfs_trans_commit(tp);
935                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
936                 if (error)
937                         return error;
938 
939                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
940                         return xfs_alert_fsblock_zero(ip, &imap);
941 
942                 if ((numblks_fsb = imap.br_blockcount) == 0) {
943                         /*
944                          * The numblks_fsb value should always get
945                          * smaller, otherwise the loop is stuck.
946                          */
947                         ASSERT(imap.br_blockcount);
948                         break;
949                 }
950                 offset_fsb += numblks_fsb;
951                 count_fsb -= numblks_fsb;
952         } while (count_fsb > 0);
953 
954         return 0;
955 
956 error_on_bmapi_transaction:
957         xfs_bmap_cancel(&free_list);
958         xfs_trans_cancel(tp);
959         xfs_iunlock(ip, XFS_ILOCK_EXCL);
960         return error;
961 }
962 

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