SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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_dir2.h"
  27 #include "xfs_alloc.h"
  28 #include "xfs_dmapi.h"
  29 #include "xfs_quota.h"
  30 #include "xfs_mount.h"
  31 #include "xfs_bmap_btree.h"
  32 #include "xfs_alloc_btree.h"
  33 #include "xfs_ialloc_btree.h"
  34 #include "xfs_dir2_sf.h"
  35 #include "xfs_attr_sf.h"
  36 #include "xfs_dinode.h"
  37 #include "xfs_inode.h"
  38 #include "xfs_ialloc.h"
  39 #include "xfs_btree.h"
  40 #include "xfs_bmap.h"
  41 #include "xfs_rtalloc.h"
  42 #include "xfs_error.h"
  43 #include "xfs_itable.h"
  44 #include "xfs_rw.h"
  45 #include "xfs_attr.h"
  46 #include "xfs_buf_item.h"
  47 #include "xfs_trans_space.h"
  48 #include "xfs_utils.h"
  49 #include "xfs_iomap.h"
  50 #include "xfs_trace.h"
  51
  52
  53 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
  54                                                 << mp->m_writeio_log)
  55 #define XFS_STRAT_WRITE_IMAPS   2
  56 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  57
  58 STATIC int
  59 xfs_imap_to_bmap(
  60         xfs_inode_t     *ip,
  61         xfs_off_t       offset,
  62         xfs_bmbt_irec_t *imap,
  63         xfs_iomap_t     *iomapp,
  64         int             imaps,                  /* Number of imap entries */
  65         int             iomaps,                 /* Number of iomap entries */
  66         int             flags)
  67 {
  68         xfs_mount_t     *mp = ip->i_mount;
  69         int             pbm;
  70         xfs_fsblock_t   start_block;
  71
  72
  73         for (pbm = 0; imaps && pbm < iomaps; imaps--, iomapp++, imap++, pbm++) {
  74                 iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
  75                 iomapp->iomap_delta = offset - iomapp->iomap_offset;
  76                 iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
  77                 iomapp->iomap_flags = flags;
  78
  79                 if (XFS_IS_REALTIME_INODE(ip)) {
  80                         iomapp->iomap_flags |= IOMAP_REALTIME;
  81                         iomapp->iomap_target = mp->m_rtdev_targp;
  82                 } else {
  83                         iomapp->iomap_target = mp->m_ddev_targp;
  84                 }
  85                 start_block = imap->br_startblock;
  86                 if (start_block == HOLESTARTBLOCK) {
  87                         iomapp->iomap_bn = IOMAP_DADDR_NULL;
  88                         iomapp->iomap_flags |= IOMAP_HOLE;
  89                 } else if (start_block == DELAYSTARTBLOCK) {
  90                         iomapp->iomap_bn = IOMAP_DADDR_NULL;
  91                         iomapp->iomap_flags |= IOMAP_DELAY;
  92                 } else {
  93                         iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
  94                         if (ISUNWRITTEN(imap))
  95                                 iomapp->iomap_flags |= IOMAP_UNWRITTEN;
  96                 }
  97
  98                 offset += iomapp->iomap_bsize - iomapp->iomap_delta;
  99         }
 100         return pbm;     /* Return the number filled */
 101 }
 102
 103 int
 104 xfs_iomap(
 105         xfs_inode_t     *ip,
 106         xfs_off_t       offset,
 107         ssize_t         count,
 108         int             flags,
 109         xfs_iomap_t     *iomapp,
 110         int             *niomaps)
 111 {
 112         xfs_mount_t     *mp = ip->i_mount;
 113         xfs_fileoff_t   offset_fsb, end_fsb;
 114         int             error = 0;
 115         int             lockmode = 0;
 116         xfs_bmbt_irec_t imap;
 117         int             nimaps = 1;
 118         int             bmapi_flags = 0;
 119         int             iomap_flags = 0;
 120
 121         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
 122
 123         if (XFS_FORCED_SHUTDOWN(mp))
 124                 return XFS_ERROR(EIO);
 125
 126         trace_xfs_iomap_enter(ip, offset, count, flags, NULL);
 127
 128         switch (flags & (BMAPI_READ | BMAPI_WRITE | BMAPI_ALLOCATE)) {
 129         case BMAPI_READ:
 130                 lockmode = xfs_ilock_map_shared(ip);
 131                 bmapi_flags = XFS_BMAPI_ENTIRE;
 132                 break;
 133         case BMAPI_WRITE:
 134                 lockmode = XFS_ILOCK_EXCL;
 135                 if (flags & BMAPI_IGNSTATE)
 136                         bmapi_flags |= XFS_BMAPI_IGSTATE|XFS_BMAPI_ENTIRE;
 137                 xfs_ilock(ip, lockmode);
 138                 break;
 139         case BMAPI_ALLOCATE:
 140                 lockmode = XFS_ILOCK_SHARED;
 141                 bmapi_flags = XFS_BMAPI_ENTIRE;
 142
 143                 /* Attempt non-blocking lock */
 144                 if (flags & BMAPI_TRYLOCK) {
 145                         if (!xfs_ilock_nowait(ip, lockmode))
 146                                 return XFS_ERROR(EAGAIN);
 147                 } else {
 148                         xfs_ilock(ip, lockmode);
 149                 }
 150                 break;
 151         default:
 152                 BUG();
 153         }
 154
 155         ASSERT(offset <= mp->m_maxioffset);
 156         if ((xfs_fsize_t)offset + count > mp->m_maxioffset)
 157                 count = mp->m_maxioffset - offset;
 158         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 159         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 160
 161         error = xfs_bmapi(NULL, ip, offset_fsb,
 162                         (xfs_filblks_t)(end_fsb - offset_fsb),
 163                         bmapi_flags,  NULL, 0, &imap,
 164                         &nimaps, NULL, NULL);
 165
 166         if (error)
 167                 goto out;
 168
 169         switch (flags & (BMAPI_WRITE|BMAPI_ALLOCATE)) {
 170         case BMAPI_WRITE:
 171                 /* If we found an extent, return it */
 172                 if (nimaps &&
 173                     (imap.br_startblock != HOLESTARTBLOCK) &&
 174                     (imap.br_startblock != DELAYSTARTBLOCK)) {
 175                         trace_xfs_iomap_found(ip, offset, count, flags, &imap);
 176                         break;
 177                 }
 178
 179                 if (flags & (BMAPI_DIRECT|BMAPI_MMAP)) {
 180                         error = xfs_iomap_write_direct(ip, offset, count, flags,
 181                                                        &imap, &nimaps, nimaps);
 182                 } else {
 183                         error = xfs_iomap_write_delay(ip, offset, count, flags,
 184                                                       &imap, &nimaps);
 185                 }
 186                 if (!error) {
 187                         trace_xfs_iomap_alloc(ip, offset, count, flags, &imap);
 188                 }
 189                 iomap_flags = IOMAP_NEW;
 190                 break;
 191         case BMAPI_ALLOCATE:
 192                 /* If we found an extent, return it */
 193                 xfs_iunlock(ip, lockmode);
 194                 lockmode = 0;
 195
 196                 if (nimaps && !isnullstartblock(imap.br_startblock)) {
 197                         trace_xfs_iomap_found(ip, offset, count, flags, &imap);
 198                         break;
 199                 }
 200
 201                 error = xfs_iomap_write_allocate(ip, offset, count,
 202                                                  &imap, &nimaps);
 203                 break;
 204         }
 205
 206         if (nimaps) {
 207                 *niomaps = xfs_imap_to_bmap(ip, offset, &imap,
 208                                             iomapp, nimaps, *niomaps, iomap_flags);
 209         } else if (niomaps) {
 210                 *niomaps = 0;
 211         }
 212
 213 out:
 214         if (lockmode)
 215                 xfs_iunlock(ip, lockmode);
 216         return XFS_ERROR(error);
 217 }
 218
 219
 220 STATIC int
 221 xfs_iomap_eof_align_last_fsb(
 222         xfs_mount_t     *mp,
 223         xfs_inode_t     *ip,
 224         xfs_extlen_t    extsize,
 225         xfs_fileoff_t   *last_fsb)
 226 {
 227         xfs_fileoff_t   new_last_fsb = 0;
 228         xfs_extlen_t    align;
 229         int             eof, error;
 230
 231         if (XFS_IS_REALTIME_INODE(ip))
 232                 ;
 233         /*
 234          * If mounted with the "-o swalloc" option, roundup the allocation
 235          * request to a stripe width boundary if the file size is >=
 236          * stripe width and we are allocating past the allocation eof.
 237          */
 238         else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
 239                 (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
 240                 new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
 241         /*
 242          * Roundup the allocation request to a stripe unit (m_dalign) boundary
 243          * if the file size is >= stripe unit size, and we are allocating past
 244          * the allocation eof.
 245          */
 246         else if (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
 247                 new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
 248
 249         /*
 250          * Always round up the allocation request to an extent boundary
 251          * (when file on a real-time subvolume or has di_extsize hint).
 252          */
 253         if (extsize) {
 254                 if (new_last_fsb)
 255                         align = roundup_64(new_last_fsb, extsize);
 256                 else
 257                         align = extsize;
 258                 new_last_fsb = roundup_64(*last_fsb, align);
 259         }
 260
 261         if (new_last_fsb) {
 262                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 263                 if (error)
 264                         return error;
 265                 if (eof)
 266                         *last_fsb = new_last_fsb;
 267         }
 268         return 0;
 269 }
 270
 271 STATIC int
 272 xfs_cmn_err_fsblock_zero(
 273         xfs_inode_t     *ip,
 274         xfs_bmbt_irec_t *imap)
 275 {
 276         xfs_cmn_err(XFS_PTAG_FSBLOCK_ZERO, CE_ALERT, ip->i_mount,
 277                         "Access to block zero in inode %llu "
 278                         "start_block: %llx start_off: %llx "
 279                         "blkcnt: %llx extent-state: %x\n",
 280                 (unsigned long long)ip->i_ino,
 281                 (unsigned long long)imap->br_startblock,
 282                 (unsigned long long)imap->br_startoff,
 283                 (unsigned long long)imap->br_blockcount,
 284                 imap->br_state);
 285         return EFSCORRUPTED;
 286 }
 287
 288 int
 289 xfs_iomap_write_direct(
 290         xfs_inode_t     *ip,
 291         xfs_off_t       offset,
 292         size_t          count,
 293         int             flags,
 294         xfs_bmbt_irec_t *ret_imap,
 295         int             *nmaps,
 296         int             found)
 297 {
 298         xfs_mount_t     *mp = ip->i_mount;
 299         xfs_fileoff_t   offset_fsb;
 300         xfs_fileoff_t   last_fsb;
 301         xfs_filblks_t   count_fsb, resaligned;
 302         xfs_fsblock_t   firstfsb;
 303         xfs_extlen_t    extsz, temp;
 304         int             nimaps;
 305         int             bmapi_flag;
 306         int             quota_flag;
 307         int             rt;
 308         xfs_trans_t     *tp;
 309         xfs_bmbt_irec_t imap;
 310         xfs_bmap_free_t free_list;
 311         uint            qblocks, resblks, resrtextents;
 312         int             committed;
 313         int             error;
 314
 315         /*
 316          * Make sure that the dquots are there. This doesn't hold
 317          * the ilock across a disk read.
 318          */
 319         error = xfs_qm_dqattach_locked(ip, 0);
 320         if (error)
 321                 return XFS_ERROR(error);
 322
 323         rt = XFS_IS_REALTIME_INODE(ip);
 324         extsz = xfs_get_extsz_hint(ip);
 325
 326         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 327         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 328         if ((offset + count) > ip->i_size) {
 329                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 330                 if (error)
 331                         goto error_out;
 332         } else {
 333                 if (found && (ret_imap->br_startblock == HOLESTARTBLOCK))
 334                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 335                                         ret_imap->br_blockcount +
 336                                         ret_imap->br_startoff);
 337         }
 338         count_fsb = last_fsb - offset_fsb;
 339         ASSERT(count_fsb > 0);
 340
 341         resaligned = count_fsb;
 342         if (unlikely(extsz)) {
 343                 if ((temp = do_mod(offset_fsb, extsz)))
 344                         resaligned += temp;
 345                 if ((temp = do_mod(resaligned, extsz)))
 346                         resaligned += extsz - temp;
 347         }
 348
 349         if (unlikely(rt)) {
 350                 resrtextents = qblocks = resaligned;
 351                 resrtextents /= mp->m_sb.sb_rextsize;
 352                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 353                 quota_flag = XFS_QMOPT_RES_RTBLKS;
 354         } else {
 355                 resrtextents = 0;
 356                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 357                 quota_flag = XFS_QMOPT_RES_REGBLKS;
 358         }
 359
 360         /*
 361          * Allocate and setup the transaction
 362          */
 363         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 364         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 365         error = xfs_trans_reserve(tp, resblks,
 366                         XFS_WRITE_LOG_RES(mp), resrtextents,
 367                         XFS_TRANS_PERM_LOG_RES,
 368                         XFS_WRITE_LOG_COUNT);
 369         /*
 370          * Check for running out of space, note: need lock to return
 371          */
 372         if (error)
 373                 xfs_trans_cancel(tp, 0);
 374         xfs_ilock(ip, XFS_ILOCK_EXCL);
 375         if (error)
 376                 goto error_out;
 377
 378         error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 379         if (error)
 380                 goto error1;
 381
 382         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 383         xfs_trans_ihold(tp, ip);
 384
 385         bmapi_flag = XFS_BMAPI_WRITE;
 386         if ((flags & BMAPI_DIRECT) && (offset < ip->i_size || extsz))
 387                 bmapi_flag |= XFS_BMAPI_PREALLOC;
 388
 389         /*
 390          * Issue the xfs_bmapi() call to allocate the blocks
 391          */
 392         xfs_bmap_init(&free_list, &firstfsb);
 393         nimaps = 1;
 394         error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 395                 &firstfsb, 0, &imap, &nimaps, &free_list, NULL);
 396         if (error)
 397                 goto error0;
 398
 399         /*
 400          * Complete the transaction
 401          */
 402         error = xfs_bmap_finish(&tp, &free_list, &committed);
 403         if (error)
 404                 goto error0;
 405         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 406         if (error)
 407                 goto error_out;
 408
 409         /*
 410          * Copy any maps to caller's array and return any error.
 411          */
 412         if (nimaps == 0) {
 413                 error = ENOSPC;
 414                 goto error_out;
 415         }
 416
 417         if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) {
 418                 error = xfs_cmn_err_fsblock_zero(ip, &imap);
 419                 goto error_out;
 420         }
 421
 422         *ret_imap = imap;
 423         *nmaps = 1;
 424         return 0;
 425
 426 error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
 427         xfs_bmap_cancel(&free_list);
 428         xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 429
 430 error1: /* Just cancel transaction */
 431         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 432         *nmaps = 0;     /* nothing set-up here */
 433
 434 error_out:
 435         return XFS_ERROR(error);
 436 }
 437
 438 /*
 439  * If the caller is doing a write at the end of the file, then extend the
 440  * allocation out to the file system's write iosize.  We clean up any extra
 441  * space left over when the file is closed in xfs_inactive().
 442  */
 443 STATIC int
 444 xfs_iomap_eof_want_preallocate(
 445         xfs_mount_t     *mp,
 446         xfs_inode_t     *ip,
 447         xfs_off_t       offset,
 448         size_t          count,
 449         int             ioflag,
 450         xfs_bmbt_irec_t *imap,
 451         int             nimaps,
 452         int             *prealloc)
 453 {
 454         xfs_fileoff_t   start_fsb;
 455         xfs_filblks_t   count_fsb;
 456         xfs_fsblock_t   firstblock;
 457         int             n, error, imaps;
 458
 459         *prealloc = 0;
 460         if ((offset + count) <= ip->i_size)
 461                 return 0;
 462
 463         /*
 464          * If there are any real blocks past eof, then don't
 465          * do any speculative allocation.
 466          */
 467         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 468         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
 469         while (count_fsb > 0) {
 470                 imaps = nimaps;
 471                 firstblock = NULLFSBLOCK;
 472                 error = xfs_bmapi(NULL, ip, start_fsb, count_fsb, 0,
 473                                   &firstblock, 0, imap, &imaps, NULL, NULL);
 474                 if (error)
 475                         return error;
 476                 for (n = 0; n < imaps; n++) {
 477                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 478                             (imap[n].br_startblock != DELAYSTARTBLOCK))
 479                                 return 0;
 480                         start_fsb += imap[n].br_blockcount;
 481                         count_fsb -= imap[n].br_blockcount;
 482                 }
 483         }
 484         *prealloc = 1;
 485         return 0;
 486 }
 487
 488 int
 489 xfs_iomap_write_delay(
 490         xfs_inode_t     *ip,
 491         xfs_off_t       offset,
 492         size_t          count,
 493         int             ioflag,
 494         xfs_bmbt_irec_t *ret_imap,
 495         int             *nmaps)
 496 {
 497         xfs_mount_t     *mp = ip->i_mount;
 498         xfs_fileoff_t   offset_fsb;
 499         xfs_fileoff_t   last_fsb;
 500         xfs_off_t       aligned_offset;
 501         xfs_fileoff_t   ioalign;
 502         xfs_fsblock_t   firstblock;
 503         xfs_extlen_t    extsz;
 504         int             nimaps;
 505         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 506         int             prealloc, flushed = 0;
 507         int             error;
 508
 509         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 510
 511         /*
 512          * Make sure that the dquots are there. This doesn't hold
 513          * the ilock across a disk read.
 514          */
 515         error = xfs_qm_dqattach_locked(ip, 0);
 516         if (error)
 517                 return XFS_ERROR(error);
 518
 519         extsz = xfs_get_extsz_hint(ip);
 520         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 521
 522         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 523                                 ioflag, imap, XFS_WRITE_IMAPS, &prealloc);
 524         if (error)
 525                 return error;
 526
 527 retry:
 528         if (prealloc) {
 529                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 530                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 531                 last_fsb = ioalign + mp->m_writeio_blocks;
 532         } else {
 533                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 534         }
 535
 536         if (prealloc || extsz) {
 537                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 538                 if (error)
 539                         return error;
 540         }
 541
 542         nimaps = XFS_WRITE_IMAPS;
 543         firstblock = NULLFSBLOCK;
 544         error = xfs_bmapi(NULL, ip, offset_fsb,
 545                           (xfs_filblks_t)(last_fsb - offset_fsb),
 546                           XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
 547                           XFS_BMAPI_ENTIRE, &firstblock, 1, imap,
 548                           &nimaps, NULL, NULL);
 549         if (error && (error != ENOSPC))
 550                 return XFS_ERROR(error);
 551
 552         /*
 553          * If bmapi returned us nothing, and if we didn't get back EDQUOT,
 554          * then we must have run out of space - flush all other inodes with
 555          * delalloc blocks and retry without EOF preallocation.
 556          */
 557         if (nimaps == 0) {
 558                 trace_xfs_delalloc_enospc(ip, offset, count);
 559                 if (flushed)
 560                         return XFS_ERROR(ENOSPC);
 561
 562                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 563                 xfs_flush_inodes(ip);
 564                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 565
 566                 flushed = 1;
 567                 error = 0;
 568                 prealloc = 0;
 569                 goto retry;
 570         }
 571
 572         if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 573                 return xfs_cmn_err_fsblock_zero(ip, &imap[0]);
 574
 575         *ret_imap = imap[0];
 576         *nmaps = 1;
 577
 578         return 0;
 579 }
 580
 581 /*
 582  * Pass in a delayed allocate extent, convert it to real extents;
 583  * return to the caller the extent we create which maps on top of
 584  * the originating callers request.
 585  *
 586  * Called without a lock on the inode.
 587  *
 588  * We no longer bother to look at the incoming map - all we have to
 589  * guarantee is that whatever we allocate fills the required range.
 590  */
 591 int
 592 xfs_iomap_write_allocate(
 593         xfs_inode_t     *ip,
 594         xfs_off_t       offset,
 595         size_t          count,
 596         xfs_bmbt_irec_t *map,
 597         int             *retmap)
 598 {
 599         xfs_mount_t     *mp = ip->i_mount;
 600         xfs_fileoff_t   offset_fsb, last_block;
 601         xfs_fileoff_t   end_fsb, map_start_fsb;
 602         xfs_fsblock_t   first_block;
 603         xfs_bmap_free_t free_list;
 604         xfs_filblks_t   count_fsb;
 605         xfs_bmbt_irec_t imap;
 606         xfs_trans_t     *tp;
 607         int             nimaps, committed;
 608         int             error = 0;
 609         int             nres;
 610
 611         *retmap = 0;
 612
 613         /*
 614          * Make sure that the dquots are there.
 615          */
 616         error = xfs_qm_dqattach(ip, 0);
 617         if (error)
 618                 return XFS_ERROR(error);
 619
 620         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 621         count_fsb = map->br_blockcount;
 622         map_start_fsb = map->br_startoff;
 623
 624         XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 625
 626         while (count_fsb != 0) {
 627                 /*
 628                  * Set up a transaction with which to allocate the
 629                  * backing store for the file.  Do allocations in a
 630                  * loop until we get some space in the range we are
 631                  * interested in.  The other space that might be allocated
 632                  * is in the delayed allocation extent on which we sit
 633                  * but before our buffer starts.
 634                  */
 635
 636                 nimaps = 0;
 637                 while (nimaps == 0) {
 638                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 639                         tp->t_flags |= XFS_TRANS_RESERVE;
 640                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 641                         error = xfs_trans_reserve(tp, nres,
 642                                         XFS_WRITE_LOG_RES(mp),
 643                                         0, XFS_TRANS_PERM_LOG_RES,
 644                                         XFS_WRITE_LOG_COUNT);
 645                         if (error) {
 646                                 xfs_trans_cancel(tp, 0);
 647                                 return XFS_ERROR(error);
 648                         }
 649                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 650                         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 651                         xfs_trans_ihold(tp, ip);
 652
 653                         xfs_bmap_init(&free_list, &first_block);
 654
 655                         /*
 656                          * it is possible that the extents have changed since
 657                          * we did the read call as we dropped the ilock for a
 658                          * while. We have to be careful about truncates or hole
 659                          * punchs here - we are not allowed to allocate
 660                          * non-delalloc blocks here.
 661                          *
 662                          * The only protection against truncation is the pages
 663                          * for the range we are being asked to convert are
 664                          * locked and hence a truncate will block on them
 665                          * first.
 666                          *
 667                          * As a result, if we go beyond the range we really
 668                          * need and hit an delalloc extent boundary followed by
 669                          * a hole while we have excess blocks in the map, we
 670                          * will fill the hole incorrectly and overrun the
 671                          * transaction reservation.
 672                          *
 673                          * Using a single map prevents this as we are forced to
 674                          * check each map we look for overlap with the desired
 675                          * range and abort as soon as we find it. Also, given
 676                          * that we only return a single map, having one beyond
 677                          * what we can return is probably a bit silly.
 678                          *
 679                          * We also need to check that we don't go beyond EOF;
 680                          * this is a truncate optimisation as a truncate sets
 681                          * the new file size before block on the pages we
 682                          * currently have locked under writeback. Because they
 683                          * are about to be tossed, we don't need to write them
 684                          * back....
 685                          */
 686                         nimaps = 1;
 687                         end_fsb = XFS_B_TO_FSB(mp, ip->i_size);
 688                         error = xfs_bmap_last_offset(NULL, ip, &last_block,
 689                                                         XFS_DATA_FORK);
 690                         if (error)
 691                                 goto trans_cancel;
 692
 693                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 694                         if ((map_start_fsb + count_fsb) > last_block) {
 695                                 count_fsb = last_block - map_start_fsb;
 696                                 if (count_fsb == 0) {
 697                                         error = EAGAIN;
 698                                         goto trans_cancel;
 699                                 }
 700                         }
 701
 702                         /* Go get the actual blocks */
 703                         error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
 704                                         XFS_BMAPI_WRITE, &first_block, 1,
 705                                         &imap, &nimaps, &free_list, NULL);
 706                         if (error)
 707                                 goto trans_cancel;
 708
 709                         error = xfs_bmap_finish(&tp, &free_list, &committed);
 710                         if (error)
 711                                 goto trans_cancel;
 712
 713                         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 714                         if (error)
 715                                 goto error0;
 716
 717                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 718                 }
 719
 720                 /*
 721                  * See if we were able to allocate an extent that
 722                  * covers at least part of the callers request
 723                  */
 724                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 725                         return xfs_cmn_err_fsblock_zero(ip, &imap);
 726
 727                 if ((offset_fsb >= imap.br_startoff) &&
 728                     (offset_fsb < (imap.br_startoff +
 729                                    imap.br_blockcount))) {
 730                         *map = imap;
 731                         *retmap = 1;
 732                         XFS_STATS_INC(xs_xstrat_quick);
 733                         return 0;
 734                 }
 735
 736                 /*
 737                  * So far we have not mapped the requested part of the
 738                  * file, just surrounding data, try again.
 739                  */
 740                 count_fsb -= imap.br_blockcount;
 741                 map_start_fsb = imap.br_startoff + imap.br_blockcount;
 742         }
 743
 744 trans_cancel:
 745         xfs_bmap_cancel(&free_list);
 746         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 747 error0:
 748         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 749         return XFS_ERROR(error);
 750 }
 751
 752 int
 753 xfs_iomap_write_unwritten(
 754         xfs_inode_t     *ip,
 755         xfs_off_t       offset,
 756         size_t          count)
 757 {
 758         xfs_mount_t     *mp = ip->i_mount;
 759         xfs_fileoff_t   offset_fsb;
 760         xfs_filblks_t   count_fsb;
 761         xfs_filblks_t   numblks_fsb;
 762         xfs_fsblock_t   firstfsb;
 763         int             nimaps;
 764         xfs_trans_t     *tp;
 765         xfs_bmbt_irec_t imap;
 766         xfs_bmap_free_t free_list;
 767         uint            resblks;
 768         int             committed;
 769         int             error;
 770
 771         trace_xfs_unwritten_convert(ip, offset, count);
 772
 773         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 774         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 775         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 776
 777         /*
 778          * Reserve enough blocks in this transaction for two complete extent
 779          * btree splits.  We may be converting the middle part of an unwritten
 780          * extent and in this case we will insert two new extents in the btree
 781          * each of which could cause a full split.
 782          *
 783          * This reservation amount will be used in the first call to
 784          * xfs_bmbt_split() to select an AG with enough space to satisfy the
 785          * rest of the operation.
 786          */
 787         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 788
 789         do {
 790                 /*
 791                  * set up a transaction to convert the range of extents
 792                  * from unwritten to real. Do allocations in a loop until
 793                  * we have covered the range passed in.
 794                  *
 795                  * Note that we open code the transaction allocation here
 796                  * to pass KM_NOFS--we can't risk to recursing back into
 797                  * the filesystem here as we might be asked to write out
 798                  * the same inode that we complete here and might deadlock
 799                  * on the iolock.
 800                  */
 801                 xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
 802                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 803                 tp->t_flags |= XFS_TRANS_RESERVE;
 804                 error = xfs_trans_reserve(tp, resblks,
 805                                 XFS_WRITE_LOG_RES(mp), 0,
 806                                 XFS_TRANS_PERM_LOG_RES,
 807                                 XFS_WRITE_LOG_COUNT);
 808                 if (error) {
 809                         xfs_trans_cancel(tp, 0);
 810                         return XFS_ERROR(error);
 811                 }
 812
 813                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 814                 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 815                 xfs_trans_ihold(tp, ip);
 816
 817                 /*
 818                  * Modify the unwritten extent state of the buffer.
 819                  */
 820                 xfs_bmap_init(&free_list, &firstfsb);
 821                 nimaps = 1;
 822                 error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
 823                                   XFS_BMAPI_WRITE|XFS_BMAPI_CONVERT, &firstfsb,
 824                                   1, &imap, &nimaps, &free_list, NULL);
 825                 if (error)
 826                         goto error_on_bmapi_transaction;
 827
 828                 error = xfs_bmap_finish(&(tp), &(free_list), &committed);
 829                 if (error)
 830                         goto error_on_bmapi_transaction;
 831
 832                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 833                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 834                 if (error)
 835                         return XFS_ERROR(error);
 836
 837                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 838                         return xfs_cmn_err_fsblock_zero(ip, &imap);
 839
 840                 if ((numblks_fsb = imap.br_blockcount) == 0) {
 841                         /*
 842                          * The numblks_fsb value should always get
 843                          * smaller, otherwise the loop is stuck.
 844                          */
 845                         ASSERT(imap.br_blockcount);
 846                         break;
 847                 }
 848                 offset_fsb += numblks_fsb;
 849                 count_fsb -= numblks_fsb;
 850         } while (count_fsb > 0);
 851
 852         return 0;
 853
 854 error_on_bmapi_transaction:
 855         xfs_bmap_cancel(&free_list);
 856         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 857         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 858         return XFS_ERROR(error);
 859 }