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_STRAT_WRITE_IMAPS   2
  51 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  52
  53 STATIC int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t,
  54                                   int, struct xfs_bmbt_irec *, int *);
  55 STATIC int xfs_iomap_write_delay(struct xfs_inode *, xfs_off_t, size_t, int,
  56                                  struct xfs_bmbt_irec *, int *);
  57 STATIC int xfs_iomap_write_allocate(struct xfs_inode *, xfs_off_t, size_t,
  58                                 struct xfs_bmbt_irec *, int *);
  59
  60 int
  61 xfs_iomap(
  62         struct xfs_inode        *ip,
  63         xfs_off_t               offset,
  64         ssize_t                 count,
  65         int                     flags,
  66         struct xfs_bmbt_irec    *imap,
  67         int                     *nimaps,
  68         int                     *new)
  69 {
  70         struct xfs_mount        *mp = ip->i_mount;
  71         xfs_fileoff_t           offset_fsb, end_fsb;
  72         int                     error = 0;
  73         int                     lockmode = 0;
  74         int                     bmapi_flags = 0;
  75
  76         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
  77
  78         *new = 0;
  79
  80         if (XFS_FORCED_SHUTDOWN(mp))
  81                 return XFS_ERROR(EIO);
  82
  83         trace_xfs_iomap_enter(ip, offset, count, flags, NULL);
  84
  85         switch (flags & (BMAPI_READ | BMAPI_WRITE | BMAPI_ALLOCATE)) {
  86         case BMAPI_READ:
  87                 lockmode = xfs_ilock_map_shared(ip);
  88                 bmapi_flags = XFS_BMAPI_ENTIRE;
  89                 break;
  90         case BMAPI_WRITE:
  91                 lockmode = XFS_ILOCK_EXCL;
  92                 if (flags & BMAPI_IGNSTATE)
  93                         bmapi_flags |= XFS_BMAPI_IGSTATE|XFS_BMAPI_ENTIRE;
  94                 xfs_ilock(ip, lockmode);
  95                 break;
  96         case BMAPI_ALLOCATE:
  97                 lockmode = XFS_ILOCK_SHARED;
  98                 bmapi_flags = XFS_BMAPI_ENTIRE;
  99
 100                 /* Attempt non-blocking lock */
 101                 if (flags & BMAPI_TRYLOCK) {
 102                         if (!xfs_ilock_nowait(ip, lockmode))
 103                                 return XFS_ERROR(EAGAIN);
 104                 } else {
 105                         xfs_ilock(ip, lockmode);
 106                 }
 107                 break;
 108         default:
 109                 BUG();
 110         }
 111
 112         ASSERT(offset <= mp->m_maxioffset);
 113         if ((xfs_fsize_t)offset + count > mp->m_maxioffset)
 114                 count = mp->m_maxioffset - offset;
 115         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 116         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 117
 118         error = xfs_bmapi(NULL, ip, offset_fsb,
 119                         (xfs_filblks_t)(end_fsb - offset_fsb),
 120                         bmapi_flags,  NULL, 0, imap,
 121                         nimaps, NULL);
 122
 123         if (error)
 124                 goto out;
 125
 126         switch (flags & (BMAPI_WRITE|BMAPI_ALLOCATE)) {
 127         case BMAPI_WRITE:
 128                 /* If we found an extent, return it */
 129                 if (*nimaps &&
 130                     (imap->br_startblock != HOLESTARTBLOCK) &&
 131                     (imap->br_startblock != DELAYSTARTBLOCK)) {
 132                         trace_xfs_iomap_found(ip, offset, count, flags, imap);
 133                         break;
 134                 }
 135
 136                 if (flags & BMAPI_DIRECT) {
 137                         error = xfs_iomap_write_direct(ip, offset, count, flags,
 138                                                        imap, nimaps);
 139                 } else {
 140                         error = xfs_iomap_write_delay(ip, offset, count, flags,
 141                                                       imap, nimaps);
 142                 }
 143                 if (!error) {
 144                         trace_xfs_iomap_alloc(ip, offset, count, flags, imap);
 145                 }
 146                 *new = 1;
 147                 break;
 148         case BMAPI_ALLOCATE:
 149                 /* If we found an extent, return it */
 150                 xfs_iunlock(ip, lockmode);
 151                 lockmode = 0;
 152
 153                 if (*nimaps && !isnullstartblock(imap->br_startblock)) {
 154                         trace_xfs_iomap_found(ip, offset, count, flags, imap);
 155                         break;
 156                 }
 157
 158                 error = xfs_iomap_write_allocate(ip, offset, count,
 159                                                  imap, nimaps);
 160                 break;
 161         }
 162
 163         ASSERT(*nimaps <= 1);
 164
 165 out:
 166         if (lockmode)
 167                 xfs_iunlock(ip, lockmode);
 168         return XFS_ERROR(error);
 169 }
 170
 171 STATIC int
 172 xfs_iomap_eof_align_last_fsb(
 173         xfs_mount_t     *mp,
 174         xfs_inode_t     *ip,
 175         xfs_extlen_t    extsize,
 176         xfs_fileoff_t   *last_fsb)
 177 {
 178         xfs_fileoff_t   new_last_fsb = 0;
 179         xfs_extlen_t    align;
 180         int             eof, error;
 181
 182         if (XFS_IS_REALTIME_INODE(ip))
 183                 ;
 184         /*
 185          * If mounted with the "-o swalloc" option, roundup the allocation
 186          * request to a stripe width boundary if the file size is >=
 187          * stripe width and we are allocating past the allocation eof.
 188          */
 189         else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
 190                 (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
 191                 new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
 192         /*
 193          * Roundup the allocation request to a stripe unit (m_dalign) boundary
 194          * if the file size is >= stripe unit size, and we are allocating past
 195          * the allocation eof.
 196          */
 197         else if (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
 198                 new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
 199
 200         /*
 201          * Always round up the allocation request to an extent boundary
 202          * (when file on a real-time subvolume or has di_extsize hint).
 203          */
 204         if (extsize) {
 205                 if (new_last_fsb)
 206                         align = roundup_64(new_last_fsb, extsize);
 207                 else
 208                         align = extsize;
 209                 new_last_fsb = roundup_64(*last_fsb, align);
 210         }
 211
 212         if (new_last_fsb) {
 213                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 214                 if (error)
 215                         return error;
 216                 if (eof)
 217                         *last_fsb = new_last_fsb;
 218         }
 219         return 0;
 220 }
 221
 222 STATIC int
 223 xfs_cmn_err_fsblock_zero(
 224         xfs_inode_t     *ip,
 225         xfs_bmbt_irec_t *imap)
 226 {
 227         xfs_cmn_err(XFS_PTAG_FSBLOCK_ZERO, CE_ALERT, ip->i_mount,
 228                         "Access to block zero in inode %llu "
 229                         "start_block: %llx start_off: %llx "
 230                         "blkcnt: %llx extent-state: %x\n",
 231                 (unsigned long long)ip->i_ino,
 232                 (unsigned long long)imap->br_startblock,
 233                 (unsigned long long)imap->br_startoff,
 234                 (unsigned long long)imap->br_blockcount,
 235                 imap->br_state);
 236         return EFSCORRUPTED;
 237 }
 238
 239 STATIC int
 240 xfs_iomap_write_direct(
 241         xfs_inode_t     *ip,
 242         xfs_off_t       offset,
 243         size_t          count,
 244         int             flags,
 245         xfs_bmbt_irec_t *imap,
 246         int             *nmaps)
 247 {
 248         xfs_mount_t     *mp = ip->i_mount;
 249         xfs_fileoff_t   offset_fsb;
 250         xfs_fileoff_t   last_fsb;
 251         xfs_filblks_t   count_fsb, resaligned;
 252         xfs_fsblock_t   firstfsb;
 253         xfs_extlen_t    extsz, temp;
 254         int             nimaps;
 255         int             bmapi_flag;
 256         int             quota_flag;
 257         int             rt;
 258         xfs_trans_t     *tp;
 259         xfs_bmap_free_t free_list;
 260         uint            qblocks, resblks, resrtextents;
 261         int             committed;
 262         int             error;
 263
 264         /*
 265          * Make sure that the dquots are there. This doesn't hold
 266          * the ilock across a disk read.
 267          */
 268         error = xfs_qm_dqattach_locked(ip, 0);
 269         if (error)
 270                 return XFS_ERROR(error);
 271
 272         rt = XFS_IS_REALTIME_INODE(ip);
 273         extsz = xfs_get_extsz_hint(ip);
 274
 275         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 276         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 277         if ((offset + count) > ip->i_size) {
 278                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 279                 if (error)
 280                         goto error_out;
 281         } else {
 282                 if (*nmaps && (imap->br_startblock == HOLESTARTBLOCK))
 283                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 284                                         imap->br_blockcount +
 285                                         imap->br_startoff);
 286         }
 287         count_fsb = last_fsb - offset_fsb;
 288         ASSERT(count_fsb > 0);
 289
 290         resaligned = count_fsb;
 291         if (unlikely(extsz)) {
 292                 if ((temp = do_mod(offset_fsb, extsz)))
 293                         resaligned += temp;
 294                 if ((temp = do_mod(resaligned, extsz)))
 295                         resaligned += extsz - temp;
 296         }
 297
 298         if (unlikely(rt)) {
 299                 resrtextents = qblocks = resaligned;
 300                 resrtextents /= mp->m_sb.sb_rextsize;
 301                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 302                 quota_flag = XFS_QMOPT_RES_RTBLKS;
 303         } else {
 304                 resrtextents = 0;
 305                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 306                 quota_flag = XFS_QMOPT_RES_REGBLKS;
 307         }
 308
 309         /*
 310          * Allocate and setup the transaction
 311          */
 312         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 313         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 314         error = xfs_trans_reserve(tp, resblks,
 315                         XFS_WRITE_LOG_RES(mp), resrtextents,
 316                         XFS_TRANS_PERM_LOG_RES,
 317                         XFS_WRITE_LOG_COUNT);
 318         /*
 319          * Check for running out of space, note: need lock to return
 320          */
 321         if (error)
 322                 xfs_trans_cancel(tp, 0);
 323         xfs_ilock(ip, XFS_ILOCK_EXCL);
 324         if (error)
 325                 goto error_out;
 326
 327         error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 328         if (error)
 329                 goto error1;
 330
 331         xfs_trans_ijoin(tp, ip);
 332
 333         bmapi_flag = XFS_BMAPI_WRITE;
 334         if ((flags & BMAPI_DIRECT) && (offset < ip->i_size || extsz))
 335                 bmapi_flag |= XFS_BMAPI_PREALLOC;
 336
 337         /*
 338          * Issue the xfs_bmapi() call to allocate the blocks.
 339          *
 340          * From this point onwards we overwrite the imap pointer that the
 341          * caller gave to us.
 342          */
 343         xfs_bmap_init(&free_list, &firstfsb);
 344         nimaps = 1;
 345         error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 346                 &firstfsb, 0, imap, &nimaps, &free_list);
 347         if (error)
 348                 goto error0;
 349
 350         /*
 351          * Complete the transaction
 352          */
 353         error = xfs_bmap_finish(&tp, &free_list, &committed);
 354         if (error)
 355                 goto error0;
 356         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 357         if (error)
 358                 goto error_out;
 359
 360         /*
 361          * Copy any maps to caller's array and return any error.
 362          */
 363         if (nimaps == 0) {
 364                 error = ENOSPC;
 365                 goto error_out;
 366         }
 367
 368         if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) {
 369                 error = xfs_cmn_err_fsblock_zero(ip, imap);
 370                 goto error_out;
 371         }
 372
 373         *nmaps = 1;
 374         return 0;
 375
 376 error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
 377         xfs_bmap_cancel(&free_list);
 378         xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 379
 380 error1: /* Just cancel transaction */
 381         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 382         *nmaps = 0;     /* nothing set-up here */
 383
 384 error_out:
 385         return XFS_ERROR(error);
 386 }
 387
 388 /*
 389  * If the caller is doing a write at the end of the file, then extend the
 390  * allocation out to the file system's write iosize.  We clean up any extra
 391  * space left over when the file is closed in xfs_inactive().
 392  */
 393 STATIC int
 394 xfs_iomap_eof_want_preallocate(
 395         xfs_mount_t     *mp,
 396         xfs_inode_t     *ip,
 397         xfs_off_t       offset,
 398         size_t          count,
 399         int             ioflag,
 400         xfs_bmbt_irec_t *imap,
 401         int             nimaps,
 402         int             *prealloc)
 403 {
 404         xfs_fileoff_t   start_fsb;
 405         xfs_filblks_t   count_fsb;
 406         xfs_fsblock_t   firstblock;
 407         int             n, error, imaps;
 408
 409         *prealloc = 0;
 410         if ((offset + count) <= ip->i_size)
 411                 return 0;
 412
 413         /*
 414          * If there are any real blocks past eof, then don't
 415          * do any speculative allocation.
 416          */
 417         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 418         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
 419         while (count_fsb > 0) {
 420                 imaps = nimaps;
 421                 firstblock = NULLFSBLOCK;
 422                 error = xfs_bmapi(NULL, ip, start_fsb, count_fsb, 0,
 423                                   &firstblock, 0, imap, &imaps, NULL);
 424                 if (error)
 425                         return error;
 426                 for (n = 0; n < imaps; n++) {
 427                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 428                             (imap[n].br_startblock != DELAYSTARTBLOCK))
 429                                 return 0;
 430                         start_fsb += imap[n].br_blockcount;
 431                         count_fsb -= imap[n].br_blockcount;
 432                 }
 433         }
 434         *prealloc = 1;
 435         return 0;
 436 }
 437
 438 STATIC int
 439 xfs_iomap_write_delay(
 440         xfs_inode_t     *ip,
 441         xfs_off_t       offset,
 442         size_t          count,
 443         int             ioflag,
 444         xfs_bmbt_irec_t *ret_imap,
 445         int             *nmaps)
 446 {
 447         xfs_mount_t     *mp = ip->i_mount;
 448         xfs_fileoff_t   offset_fsb;
 449         xfs_fileoff_t   last_fsb;
 450         xfs_off_t       aligned_offset;
 451         xfs_fileoff_t   ioalign;
 452         xfs_fsblock_t   firstblock;
 453         xfs_extlen_t    extsz;
 454         int             nimaps;
 455         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 456         int             prealloc, flushed = 0;
 457         int             error;
 458
 459         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 460
 461         /*
 462          * Make sure that the dquots are there. This doesn't hold
 463          * the ilock across a disk read.
 464          */
 465         error = xfs_qm_dqattach_locked(ip, 0);
 466         if (error)
 467                 return XFS_ERROR(error);
 468
 469         extsz = xfs_get_extsz_hint(ip);
 470         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 471
 472         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 473                                 ioflag, imap, XFS_WRITE_IMAPS, &prealloc);
 474         if (error)
 475                 return error;
 476
 477 retry:
 478         if (prealloc) {
 479                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 480                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 481                 last_fsb = ioalign + mp->m_writeio_blocks;
 482         } else {
 483                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 484         }
 485
 486         if (prealloc || extsz) {
 487                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 488                 if (error)
 489                         return error;
 490         }
 491
 492         nimaps = XFS_WRITE_IMAPS;
 493         firstblock = NULLFSBLOCK;
 494         error = xfs_bmapi(NULL, ip, offset_fsb,
 495                           (xfs_filblks_t)(last_fsb - offset_fsb),
 496                           XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
 497                           XFS_BMAPI_ENTIRE, &firstblock, 1, imap,
 498                           &nimaps, NULL);
 499         if (error && (error != ENOSPC))
 500                 return XFS_ERROR(error);
 501
 502         /*
 503          * If bmapi returned us nothing, and if we didn't get back EDQUOT,
 504          * then we must have run out of space - flush all other inodes with
 505          * delalloc blocks and retry without EOF preallocation.
 506          */
 507         if (nimaps == 0) {
 508                 trace_xfs_delalloc_enospc(ip, offset, count);
 509                 if (flushed)
 510                         return XFS_ERROR(ENOSPC);
 511
 512                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 513                 xfs_flush_inodes(ip);
 514                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 515
 516                 flushed = 1;
 517                 error = 0;
 518                 prealloc = 0;
 519                 goto retry;
 520         }
 521
 522         if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 523                 return xfs_cmn_err_fsblock_zero(ip, &imap[0]);
 524
 525         *ret_imap = imap[0];
 526         *nmaps = 1;
 527
 528         return 0;
 529 }
 530
 531 /*
 532  * Pass in a delayed allocate extent, convert it to real extents;
 533  * return to the caller the extent we create which maps on top of
 534  * the originating callers request.
 535  *
 536  * Called without a lock on the inode.
 537  *
 538  * We no longer bother to look at the incoming map - all we have to
 539  * guarantee is that whatever we allocate fills the required range.
 540  */
 541 STATIC int
 542 xfs_iomap_write_allocate(
 543         xfs_inode_t     *ip,
 544         xfs_off_t       offset,
 545         size_t          count,
 546         xfs_bmbt_irec_t *imap,
 547         int             *retmap)
 548 {
 549         xfs_mount_t     *mp = ip->i_mount;
 550         xfs_fileoff_t   offset_fsb, last_block;
 551         xfs_fileoff_t   end_fsb, map_start_fsb;
 552         xfs_fsblock_t   first_block;
 553         xfs_bmap_free_t free_list;
 554         xfs_filblks_t   count_fsb;
 555         xfs_trans_t     *tp;
 556         int             nimaps, committed;
 557         int             error = 0;
 558         int             nres;
 559
 560         *retmap = 0;
 561
 562         /*
 563          * Make sure that the dquots are there.
 564          */
 565         error = xfs_qm_dqattach(ip, 0);
 566         if (error)
 567                 return XFS_ERROR(error);
 568
 569         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 570         count_fsb = imap->br_blockcount;
 571         map_start_fsb = imap->br_startoff;
 572
 573         XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 574
 575         while (count_fsb != 0) {
 576                 /*
 577                  * Set up a transaction with which to allocate the
 578                  * backing store for the file.  Do allocations in a
 579                  * loop until we get some space in the range we are
 580                  * interested in.  The other space that might be allocated
 581                  * is in the delayed allocation extent on which we sit
 582                  * but before our buffer starts.
 583                  */
 584
 585                 nimaps = 0;
 586                 while (nimaps == 0) {
 587                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 588                         tp->t_flags |= XFS_TRANS_RESERVE;
 589                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 590                         error = xfs_trans_reserve(tp, nres,
 591                                         XFS_WRITE_LOG_RES(mp),
 592                                         0, XFS_TRANS_PERM_LOG_RES,
 593                                         XFS_WRITE_LOG_COUNT);
 594                         if (error) {
 595                                 xfs_trans_cancel(tp, 0);
 596                                 return XFS_ERROR(error);
 597                         }
 598                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 599                         xfs_trans_ijoin(tp, ip);
 600
 601                         xfs_bmap_init(&free_list, &first_block);
 602
 603                         /*
 604                          * it is possible that the extents have changed since
 605                          * we did the read call as we dropped the ilock for a
 606                          * while. We have to be careful about truncates or hole
 607                          * punchs here - we are not allowed to allocate
 608                          * non-delalloc blocks here.
 609                          *
 610                          * The only protection against truncation is the pages
 611                          * for the range we are being asked to convert are
 612                          * locked and hence a truncate will block on them
 613                          * first.
 614                          *
 615                          * As a result, if we go beyond the range we really
 616                          * need and hit an delalloc extent boundary followed by
 617                          * a hole while we have excess blocks in the map, we
 618                          * will fill the hole incorrectly and overrun the
 619                          * transaction reservation.
 620                          *
 621                          * Using a single map prevents this as we are forced to
 622                          * check each map we look for overlap with the desired
 623                          * range and abort as soon as we find it. Also, given
 624                          * that we only return a single map, having one beyond
 625                          * what we can return is probably a bit silly.
 626                          *
 627                          * We also need to check that we don't go beyond EOF;
 628                          * this is a truncate optimisation as a truncate sets
 629                          * the new file size before block on the pages we
 630                          * currently have locked under writeback. Because they
 631                          * are about to be tossed, we don't need to write them
 632                          * back....
 633                          */
 634                         nimaps = 1;
 635                         end_fsb = XFS_B_TO_FSB(mp, ip->i_size);
 636                         error = xfs_bmap_last_offset(NULL, ip, &last_block,
 637                                                         XFS_DATA_FORK);
 638                         if (error)
 639                                 goto trans_cancel;
 640
 641                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 642                         if ((map_start_fsb + count_fsb) > last_block) {
 643                                 count_fsb = last_block - map_start_fsb;
 644                                 if (count_fsb == 0) {
 645                                         error = EAGAIN;
 646                                         goto trans_cancel;
 647                                 }
 648                         }
 649
 650                         /*
 651                          * Go get the actual blocks.
 652                          *
 653                          * From this point onwards we overwrite the imap
 654                          * pointer that the caller gave to us.
 655                          */
 656                         error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
 657                                         XFS_BMAPI_WRITE, &first_block, 1,
 658                                         imap, &nimaps, &free_list);
 659                         if (error)
 660                                 goto trans_cancel;
 661
 662                         error = xfs_bmap_finish(&tp, &free_list, &committed);
 663                         if (error)
 664                                 goto trans_cancel;
 665
 666                         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 667                         if (error)
 668                                 goto error0;
 669
 670                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 671                 }
 672
 673                 /*
 674                  * See if we were able to allocate an extent that
 675                  * covers at least part of the callers request
 676                  */
 677                 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
 678                         return xfs_cmn_err_fsblock_zero(ip, imap);
 679
 680                 if ((offset_fsb >= imap->br_startoff) &&
 681                     (offset_fsb < (imap->br_startoff +
 682                                    imap->br_blockcount))) {
 683                         *retmap = 1;
 684                         XFS_STATS_INC(xs_xstrat_quick);
 685                         return 0;
 686                 }
 687
 688                 /*
 689                  * So far we have not mapped the requested part of the
 690                  * file, just surrounding data, try again.
 691                  */
 692                 count_fsb -= imap->br_blockcount;
 693                 map_start_fsb = imap->br_startoff + imap->br_blockcount;
 694         }
 695
 696 trans_cancel:
 697         xfs_bmap_cancel(&free_list);
 698         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 699 error0:
 700         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 701         return XFS_ERROR(error);
 702 }
 703
 704 int
 705 xfs_iomap_write_unwritten(
 706         xfs_inode_t     *ip,
 707         xfs_off_t       offset,
 708         size_t          count)
 709 {
 710         xfs_mount_t     *mp = ip->i_mount;
 711         xfs_fileoff_t   offset_fsb;
 712         xfs_filblks_t   count_fsb;
 713         xfs_filblks_t   numblks_fsb;
 714         xfs_fsblock_t   firstfsb;
 715         int             nimaps;
 716         xfs_trans_t     *tp;
 717         xfs_bmbt_irec_t imap;
 718         xfs_bmap_free_t free_list;
 719         uint            resblks;
 720         int             committed;
 721         int             error;
 722
 723         trace_xfs_unwritten_convert(ip, offset, count);
 724
 725         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 726         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 727         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 728
 729         /*
 730          * Reserve enough blocks in this transaction for two complete extent
 731          * btree splits.  We may be converting the middle part of an unwritten
 732          * extent and in this case we will insert two new extents in the btree
 733          * each of which could cause a full split.
 734          *
 735          * This reservation amount will be used in the first call to
 736          * xfs_bmbt_split() to select an AG with enough space to satisfy the
 737          * rest of the operation.
 738          */
 739         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 740
 741         do {
 742                 /*
 743                  * set up a transaction to convert the range of extents
 744                  * from unwritten to real. Do allocations in a loop until
 745                  * we have covered the range passed in.
 746                  *
 747                  * Note that we open code the transaction allocation here
 748                  * to pass KM_NOFS--we can't risk to recursing back into
 749                  * the filesystem here as we might be asked to write out
 750                  * the same inode that we complete here and might deadlock
 751                  * on the iolock.
 752                  */
 753                 xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
 754                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 755                 tp->t_flags |= XFS_TRANS_RESERVE;
 756                 error = xfs_trans_reserve(tp, resblks,
 757                                 XFS_WRITE_LOG_RES(mp), 0,
 758                                 XFS_TRANS_PERM_LOG_RES,
 759                                 XFS_WRITE_LOG_COUNT);
 760                 if (error) {
 761                         xfs_trans_cancel(tp, 0);
 762                         return XFS_ERROR(error);
 763                 }
 764
 765                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 766                 xfs_trans_ijoin(tp, ip);
 767
 768                 /*
 769                  * Modify the unwritten extent state of the buffer.
 770                  */
 771                 xfs_bmap_init(&free_list, &firstfsb);
 772                 nimaps = 1;
 773                 error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
 774                                   XFS_BMAPI_WRITE|XFS_BMAPI_CONVERT, &firstfsb,
 775                                   1, &imap, &nimaps, &free_list);
 776                 if (error)
 777                         goto error_on_bmapi_transaction;
 778
 779                 error = xfs_bmap_finish(&(tp), &(free_list), &committed);
 780                 if (error)
 781                         goto error_on_bmapi_transaction;
 782
 783                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 784                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 785                 if (error)
 786                         return XFS_ERROR(error);
 787
 788                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 789                         return xfs_cmn_err_fsblock_zero(ip, &imap);
 790
 791                 if ((numblks_fsb = imap.br_blockcount) == 0) {
 792                         /*
 793                          * The numblks_fsb value should always get
 794                          * smaller, otherwise the loop is stuck.
 795                          */
 796                         ASSERT(imap.br_blockcount);
 797                         break;
 798                 }
 799                 offset_fsb += numblks_fsb;
 800                 count_fsb -= numblks_fsb;
 801         } while (count_fsb > 0);
 802
 803         return 0;
 804
 805 error_on_bmapi_transaction:
 806         xfs_bmap_cancel(&free_list);
 807         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 808         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 809         return XFS_ERROR(error);
 810 }