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_bit.h"
  21 #include "xfs_log.h"
  22 #include "xfs_inum.h"
  23 #include "xfs_trans.h"
  24 #include "xfs_sb.h"
  25 #include "xfs_ag.h"
  26 #include "xfs_alloc.h"
  27 #include "xfs_quota.h"
  28 #include "xfs_mount.h"
  29 #include "xfs_bmap_btree.h"
  30 #include "xfs_alloc_btree.h"
  31 #include "xfs_ialloc_btree.h"
  32 #include "xfs_dinode.h"
  33 #include "xfs_inode.h"
  34 #include "xfs_btree.h"
  35 #include "xfs_bmap.h"
  36 #include "xfs_rtalloc.h"
  37 #include "xfs_error.h"
  38 #include "xfs_itable.h"
  39 #include "xfs_rw.h"
  40 #include "xfs_attr.h"
  41 #include "xfs_buf_item.h"
  42 #include "xfs_trans_space.h"
  43 #include "xfs_utils.h"
  44 #include "xfs_iomap.h"
  45 #include "xfs_trace.h"
  46
  47
  48 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
  49                                                 << mp->m_writeio_log)
  50 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  51
  52 STATIC int
  53 xfs_iomap_eof_align_last_fsb(
  54         xfs_mount_t     *mp,
  55         xfs_inode_t     *ip,
  56         xfs_extlen_t    extsize,
  57         xfs_fileoff_t   *last_fsb)
  58 {
  59         xfs_fileoff_t   new_last_fsb = 0;
  60         xfs_extlen_t    align;
  61         int             eof, error;
  62
  63         if (XFS_IS_REALTIME_INODE(ip))
  64                 ;
  65         /*
  66          * If mounted with the "-o swalloc" option, roundup the allocation
  67          * request to a stripe width boundary if the file size is >=
  68          * stripe width and we are allocating past the allocation eof.
  69          */
  70         else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
  71                 (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
  72                 new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
  73         /*
  74          * Roundup the allocation request to a stripe unit (m_dalign) boundary
  75          * if the file size is >= stripe unit size, and we are allocating past
  76          * the allocation eof.
  77          */
  78         else if (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
  79                 new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
  80
  81         /*
  82          * Always round up the allocation request to an extent boundary
  83          * (when file on a real-time subvolume or has di_extsize hint).
  84          */
  85         if (extsize) {
  86                 if (new_last_fsb)
  87                         align = roundup_64(new_last_fsb, extsize);
  88                 else
  89                         align = extsize;
  90                 new_last_fsb = roundup_64(*last_fsb, align);
  91         }
  92
  93         if (new_last_fsb) {
  94                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
  95                 if (error)
  96                         return error;
  97                 if (eof)
  98                         *last_fsb = new_last_fsb;
  99         }
 100         return 0;
 101 }
 102
 103 STATIC int
 104 xfs_alert_fsblock_zero(
 105         xfs_inode_t     *ip,
 106         xfs_bmbt_irec_t *imap)
 107 {
 108         xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
 109                         "Access to block zero in inode %llu "
 110                         "start_block: %llx start_off: %llx "
 111                         "blkcnt: %llx extent-state: %x\n",
 112                 (unsigned long long)ip->i_ino,
 113                 (unsigned long long)imap->br_startblock,
 114                 (unsigned long long)imap->br_startoff,
 115                 (unsigned long long)imap->br_blockcount,
 116                 imap->br_state);
 117         return EFSCORRUPTED;
 118 }
 119
 120 int
 121 xfs_iomap_write_direct(
 122         xfs_inode_t     *ip,
 123         xfs_off_t       offset,
 124         size_t          count,
 125         xfs_bmbt_irec_t *imap,
 126         int             nmaps)
 127 {
 128         xfs_mount_t     *mp = ip->i_mount;
 129         xfs_fileoff_t   offset_fsb;
 130         xfs_fileoff_t   last_fsb;
 131         xfs_filblks_t   count_fsb, resaligned;
 132         xfs_fsblock_t   firstfsb;
 133         xfs_extlen_t    extsz, temp;
 134         int             nimaps;
 135         int             bmapi_flag;
 136         int             quota_flag;
 137         int             rt;
 138         xfs_trans_t     *tp;
 139         xfs_bmap_free_t free_list;
 140         uint            qblocks, resblks, resrtextents;
 141         int             committed;
 142         int             error;
 143
 144         /*
 145          * Make sure that the dquots are there. This doesn't hold
 146          * the ilock across a disk read.
 147          */
 148         error = xfs_qm_dqattach_locked(ip, 0);
 149         if (error)
 150                 return XFS_ERROR(error);
 151
 152         rt = XFS_IS_REALTIME_INODE(ip);
 153         extsz = xfs_get_extsz_hint(ip);
 154
 155         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 156         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 157         if ((offset + count) > ip->i_size) {
 158                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 159                 if (error)
 160                         goto error_out;
 161         } else {
 162                 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
 163                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 164                                         imap->br_blockcount +
 165                                         imap->br_startoff);
 166         }
 167         count_fsb = last_fsb - offset_fsb;
 168         ASSERT(count_fsb > 0);
 169
 170         resaligned = count_fsb;
 171         if (unlikely(extsz)) {
 172                 if ((temp = do_mod(offset_fsb, extsz)))
 173                         resaligned += temp;
 174                 if ((temp = do_mod(resaligned, extsz)))
 175                         resaligned += extsz - temp;
 176         }
 177
 178         if (unlikely(rt)) {
 179                 resrtextents = qblocks = resaligned;
 180                 resrtextents /= mp->m_sb.sb_rextsize;
 181                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 182                 quota_flag = XFS_QMOPT_RES_RTBLKS;
 183         } else {
 184                 resrtextents = 0;
 185                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 186                 quota_flag = XFS_QMOPT_RES_REGBLKS;
 187         }
 188
 189         /*
 190          * Allocate and setup the transaction
 191          */
 192         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 193         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 194         error = xfs_trans_reserve(tp, resblks,
 195                         XFS_WRITE_LOG_RES(mp), resrtextents,
 196                         XFS_TRANS_PERM_LOG_RES,
 197                         XFS_WRITE_LOG_COUNT);
 198         /*
 199          * Check for running out of space, note: need lock to return
 200          */
 201         if (error)
 202                 xfs_trans_cancel(tp, 0);
 203         xfs_ilock(ip, XFS_ILOCK_EXCL);
 204         if (error)
 205                 goto error_out;
 206
 207         error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 208         if (error)
 209                 goto error1;
 210
 211         xfs_trans_ijoin(tp, ip, 0);
 212
 213         bmapi_flag = 0;
 214         if (offset < ip->i_size || extsz)
 215                 bmapi_flag |= XFS_BMAPI_PREALLOC;
 216
 217         /*
 218          * From this point onwards we overwrite the imap pointer that the
 219          * caller gave to us.
 220          */
 221         xfs_bmap_init(&free_list, &firstfsb);
 222         nimaps = 1;
 223         error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 224                                 &firstfsb, 0, imap, &nimaps, &free_list);
 225         if (error)
 226                 goto error0;
 227
 228         /*
 229          * Complete the transaction
 230          */
 231         error = xfs_bmap_finish(&tp, &free_list, &committed);
 232         if (error)
 233                 goto error0;
 234         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 235         if (error)
 236                 goto error_out;
 237
 238         /*
 239          * Copy any maps to caller's array and return any error.
 240          */
 241         if (nimaps == 0) {
 242                 error = ENOSPC;
 243                 goto error_out;
 244         }
 245
 246         if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) {
 247                 error = xfs_alert_fsblock_zero(ip, imap);
 248                 goto error_out;
 249         }
 250
 251         return 0;
 252
 253 error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
 254         xfs_bmap_cancel(&free_list);
 255         xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 256
 257 error1: /* Just cancel transaction */
 258         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 259
 260 error_out:
 261         return XFS_ERROR(error);
 262 }
 263
 264 /*
 265  * If the caller is doing a write at the end of the file, then extend the
 266  * allocation out to the file system's write iosize.  We clean up any extra
 267  * space left over when the file is closed in xfs_inactive().
 268  *
 269  * If we find we already have delalloc preallocation beyond EOF, don't do more
 270  * preallocation as it it not needed.
 271  */
 272 STATIC int
 273 xfs_iomap_eof_want_preallocate(
 274         xfs_mount_t     *mp,
 275         xfs_inode_t     *ip,
 276         xfs_off_t       offset,
 277         size_t          count,
 278         xfs_bmbt_irec_t *imap,
 279         int             nimaps,
 280         int             *prealloc)
 281 {
 282         xfs_fileoff_t   start_fsb;
 283         xfs_filblks_t   count_fsb;
 284         xfs_fsblock_t   firstblock;
 285         int             n, error, imaps;
 286         int             found_delalloc = 0;
 287
 288         *prealloc = 0;
 289         if ((offset + count) <= ip->i_size)
 290                 return 0;
 291
 292         /*
 293          * If there are any real blocks past eof, then don't
 294          * do any speculative allocation.
 295          */
 296         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 297         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
 298         while (count_fsb > 0) {
 299                 imaps = nimaps;
 300                 firstblock = NULLFSBLOCK;
 301                 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
 302                                        0);
 303                 if (error)
 304                         return error;
 305                 for (n = 0; n < imaps; n++) {
 306                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 307                             (imap[n].br_startblock != DELAYSTARTBLOCK))
 308                                 return 0;
 309                         start_fsb += imap[n].br_blockcount;
 310                         count_fsb -= imap[n].br_blockcount;
 311
 312                         if (imap[n].br_startblock == DELAYSTARTBLOCK)
 313                                 found_delalloc = 1;
 314                 }
 315         }
 316         if (!found_delalloc)
 317                 *prealloc = 1;
 318         return 0;
 319 }
 320
 321 /*
 322  * If we don't have a user specified preallocation size, dynamically increase
 323  * the preallocation size as the size of the file grows. Cap the maximum size
 324  * at a single extent or less if the filesystem is near full. The closer the
 325  * filesystem is to full, the smaller the maximum prealocation.
 326  */
 327 STATIC xfs_fsblock_t
 328 xfs_iomap_prealloc_size(
 329         struct xfs_mount        *mp,
 330         struct xfs_inode        *ip)
 331 {
 332         xfs_fsblock_t           alloc_blocks = 0;
 333
 334         if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
 335                 int shift = 0;
 336                 int64_t freesp;
 337
 338                 /*
 339                  * rounddown_pow_of_two() returns an undefined result
 340                  * if we pass in alloc_blocks = 0. Hence the "+ 1" to
 341                  * ensure we always pass in a non-zero value.
 342                  */
 343                 alloc_blocks = XFS_B_TO_FSB(mp, ip->i_size) + 1;
 344                 alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
 345                                         rounddown_pow_of_two(alloc_blocks));
 346
 347                 xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
 348                 freesp = mp->m_sb.sb_fdblocks;
 349                 if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
 350                         shift = 2;
 351                         if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
 352                                 shift++;
 353                         if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
 354                                 shift++;
 355                         if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
 356                                 shift++;
 357                         if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
 358                                 shift++;
 359                 }
 360                 if (shift)
 361                         alloc_blocks >>= shift;
 362         }
 363
 364         if (alloc_blocks < mp->m_writeio_blocks)
 365                 alloc_blocks = mp->m_writeio_blocks;
 366
 367         return alloc_blocks;
 368 }
 369
 370 int
 371 xfs_iomap_write_delay(
 372         xfs_inode_t     *ip,
 373         xfs_off_t       offset,
 374         size_t          count,
 375         xfs_bmbt_irec_t *ret_imap)
 376 {
 377         xfs_mount_t     *mp = ip->i_mount;
 378         xfs_fileoff_t   offset_fsb;
 379         xfs_fileoff_t   last_fsb;
 380         xfs_off_t       aligned_offset;
 381         xfs_fileoff_t   ioalign;
 382         xfs_extlen_t    extsz;
 383         int             nimaps;
 384         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 385         int             prealloc, flushed = 0;
 386         int             error;
 387
 388         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 389
 390         /*
 391          * Make sure that the dquots are there. This doesn't hold
 392          * the ilock across a disk read.
 393          */
 394         error = xfs_qm_dqattach_locked(ip, 0);
 395         if (error)
 396                 return XFS_ERROR(error);
 397
 398         extsz = xfs_get_extsz_hint(ip);
 399         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 400
 401
 402         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 403                                 imap, XFS_WRITE_IMAPS, &prealloc);
 404         if (error)
 405                 return error;
 406
 407 retry:
 408         if (prealloc) {
 409                 xfs_fsblock_t   alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
 410
 411                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 412                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 413                 last_fsb = ioalign + alloc_blocks;
 414         } else {
 415                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 416         }
 417
 418         if (prealloc || extsz) {
 419                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 420                 if (error)
 421                         return error;
 422         }
 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, ip->i_size);
 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         uint            resblks;
 649         int             committed;
 650         int             error;
 651
 652         trace_xfs_unwritten_convert(ip, offset, count);
 653
 654         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 655         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 656         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 657
 658         /*
 659          * Reserve enough blocks in this transaction for two complete extent
 660          * btree splits.  We may be converting the middle part of an unwritten
 661          * extent and in this case we will insert two new extents in the btree
 662          * each of which could cause a full split.
 663          *
 664          * This reservation amount will be used in the first call to
 665          * xfs_bmbt_split() to select an AG with enough space to satisfy the
 666          * rest of the operation.
 667          */
 668         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 669
 670         do {
 671                 /*
 672                  * set up a transaction to convert the range of extents
 673                  * from unwritten to real. Do allocations in a loop until
 674                  * we have covered the range passed in.
 675                  *
 676                  * Note that we open code the transaction allocation here
 677                  * to pass KM_NOFS--we can't risk to recursing back into
 678                  * the filesystem here as we might be asked to write out
 679                  * the same inode that we complete here and might deadlock
 680                  * on the iolock.
 681                  */
 682                 xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
 683                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 684                 tp->t_flags |= XFS_TRANS_RESERVE;
 685                 error = xfs_trans_reserve(tp, resblks,
 686                                 XFS_WRITE_LOG_RES(mp), 0,
 687                                 XFS_TRANS_PERM_LOG_RES,
 688                                 XFS_WRITE_LOG_COUNT);
 689                 if (error) {
 690                         xfs_trans_cancel(tp, 0);
 691                         return XFS_ERROR(error);
 692                 }
 693
 694                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 695                 xfs_trans_ijoin(tp, ip, 0);
 696
 697                 /*
 698                  * Modify the unwritten extent state of the buffer.
 699                  */
 700                 xfs_bmap_init(&free_list, &firstfsb);
 701                 nimaps = 1;
 702                 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
 703                                   XFS_BMAPI_CONVERT, &firstfsb,
 704                                   1, &imap, &nimaps, &free_list);
 705                 if (error)
 706                         goto error_on_bmapi_transaction;
 707
 708                 error = xfs_bmap_finish(&(tp), &(free_list), &committed);
 709                 if (error)
 710                         goto error_on_bmapi_transaction;
 711
 712                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 713                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 714                 if (error)
 715                         return XFS_ERROR(error);
 716
 717                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 718                         return xfs_alert_fsblock_zero(ip, &imap);
 719
 720                 if ((numblks_fsb = imap.br_blockcount) == 0) {
 721                         /*
 722                          * The numblks_fsb value should always get
 723                          * smaller, otherwise the loop is stuck.
 724                          */
 725                         ASSERT(imap.br_blockcount);
 726                         break;
 727                 }
 728                 offset_fsb += numblks_fsb;
 729                 count_fsb -= numblks_fsb;
 730         } while (count_fsb > 0);
 731
 732         return 0;
 733
 734 error_on_bmapi_transaction:
 735         xfs_bmap_cancel(&free_list);
 736         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 737         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 738         return XFS_ERROR(error);
 739 }