git.oblomov.eu Git - 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_acl.h"
  46 #include "xfs_attr.h"
  47 #include "xfs_buf_item.h"
  48 #include "xfs_trans_space.h"
  49 #include "xfs_utils.h"
  50 #include "xfs_iomap.h"
  51
  52 #if defined(XFS_RW_TRACE)
  53 void
  54 xfs_iomap_enter_trace(
  55         int             tag,
  56         xfs_inode_t     *ip,
  57         xfs_off_t       offset,
  58         ssize_t         count)
  59 {
  60         if (!ip->i_rwtrace)
  61                 return;
  62
  63         ktrace_enter(ip->i_rwtrace,
  64                 (void *)((unsigned long)tag),
  65                 (void *)ip,
  66                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
  67                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
  68                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
  69                 (void *)((unsigned long)(offset & 0xffffffff)),
  70                 (void *)((unsigned long)count),
  71                 (void *)((unsigned long)((ip->i_new_size >> 32) & 0xffffffff)),
  72                 (void *)((unsigned long)(ip->i_new_size & 0xffffffff)),
  73                 (void *)((unsigned long)current_pid()),
  74                 (void *)NULL,
  75                 (void *)NULL,
  76                 (void *)NULL,
  77                 (void *)NULL,
  78                 (void *)NULL,
  79                 (void *)NULL);
  80 }
  81
  82 void
  83 xfs_iomap_map_trace(
  84         int             tag,
  85         xfs_inode_t     *ip,
  86         xfs_off_t       offset,
  87         ssize_t         count,
  88         xfs_iomap_t     *iomapp,
  89         xfs_bmbt_irec_t *imapp,
  90         int             flags)
  91 {
  92         if (!ip->i_rwtrace)
  93                 return;
  94
  95         ktrace_enter(ip->i_rwtrace,
  96                 (void *)((unsigned long)tag),
  97                 (void *)ip,
  98                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
  99                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
 100                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
 101                 (void *)((unsigned long)(offset & 0xffffffff)),
 102                 (void *)((unsigned long)count),
 103                 (void *)((unsigned long)flags),
 104                 (void *)((unsigned long)((iomapp->iomap_offset >> 32) & 0xffffffff)),
 105                 (void *)((unsigned long)(iomapp->iomap_offset & 0xffffffff)),
 106                 (void *)((unsigned long)(iomapp->iomap_delta)),
 107                 (void *)((unsigned long)(iomapp->iomap_bsize)),
 108                 (void *)((unsigned long)(iomapp->iomap_bn)),
 109                 (void *)(__psint_t)(imapp->br_startoff),
 110                 (void *)((unsigned long)(imapp->br_blockcount)),
 111                 (void *)(__psint_t)(imapp->br_startblock));
 112 }
 113 #else
 114 #define xfs_iomap_enter_trace(tag, io, offset, count)
 115 #define xfs_iomap_map_trace(tag, io, offset, count, iomapp, imapp, flags)
 116 #endif
 117
 118 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
 119                                                 << mp->m_writeio_log)
 120 #define XFS_STRAT_WRITE_IMAPS   2
 121 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
 122
 123 STATIC int
 124 xfs_imap_to_bmap(
 125         xfs_inode_t     *ip,
 126         xfs_off_t       offset,
 127         xfs_bmbt_irec_t *imap,
 128         xfs_iomap_t     *iomapp,
 129         int             imaps,                  /* Number of imap entries */
 130         int             iomaps,                 /* Number of iomap entries */
 131         int             flags)
 132 {
 133         xfs_mount_t     *mp = ip->i_mount;
 134         int             pbm;
 135         xfs_fsblock_t   start_block;
 136
 137
 138         for (pbm = 0; imaps && pbm < iomaps; imaps--, iomapp++, imap++, pbm++) {
 139                 iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
 140                 iomapp->iomap_delta = offset - iomapp->iomap_offset;
 141                 iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
 142                 iomapp->iomap_flags = flags;
 143
 144                 if (XFS_IS_REALTIME_INODE(ip)) {
 145                         iomapp->iomap_flags |= IOMAP_REALTIME;
 146                         iomapp->iomap_target = mp->m_rtdev_targp;
 147                 } else {
 148                         iomapp->iomap_target = mp->m_ddev_targp;
 149                 }
 150                 start_block = imap->br_startblock;
 151                 if (start_block == HOLESTARTBLOCK) {
 152                         iomapp->iomap_bn = IOMAP_DADDR_NULL;
 153                         iomapp->iomap_flags |= IOMAP_HOLE;
 154                 } else if (start_block == DELAYSTARTBLOCK) {
 155                         iomapp->iomap_bn = IOMAP_DADDR_NULL;
 156                         iomapp->iomap_flags |= IOMAP_DELAY;
 157                 } else {
 158                         iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
 159                         if (ISUNWRITTEN(imap))
 160                                 iomapp->iomap_flags |= IOMAP_UNWRITTEN;
 161                 }
 162
 163                 offset += iomapp->iomap_bsize - iomapp->iomap_delta;
 164         }
 165         return pbm;     /* Return the number filled */
 166 }
 167
 168 int
 169 xfs_iomap(
 170         xfs_inode_t     *ip,
 171         xfs_off_t       offset,
 172         ssize_t         count,
 173         int             flags,
 174         xfs_iomap_t     *iomapp,
 175         int             *niomaps)
 176 {
 177         xfs_mount_t     *mp = ip->i_mount;
 178         xfs_fileoff_t   offset_fsb, end_fsb;
 179         int             error = 0;
 180         int             lockmode = 0;
 181         xfs_bmbt_irec_t imap;
 182         int             nimaps = 1;
 183         int             bmapi_flags = 0;
 184         int             iomap_flags = 0;
 185
 186         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
 187
 188         if (XFS_FORCED_SHUTDOWN(mp))
 189                 return XFS_ERROR(EIO);
 190
 191         switch (flags & (BMAPI_READ | BMAPI_WRITE | BMAPI_ALLOCATE)) {
 192         case BMAPI_READ:
 193                 xfs_iomap_enter_trace(XFS_IOMAP_READ_ENTER, ip, offset, count);
 194                 lockmode = xfs_ilock_map_shared(ip);
 195                 bmapi_flags = XFS_BMAPI_ENTIRE;
 196                 break;
 197         case BMAPI_WRITE:
 198                 xfs_iomap_enter_trace(XFS_IOMAP_WRITE_ENTER, ip, offset, count);
 199                 lockmode = XFS_ILOCK_EXCL;
 200                 if (flags & BMAPI_IGNSTATE)
 201                         bmapi_flags |= XFS_BMAPI_IGSTATE|XFS_BMAPI_ENTIRE;
 202                 xfs_ilock(ip, lockmode);
 203                 break;
 204         case BMAPI_ALLOCATE:
 205                 xfs_iomap_enter_trace(XFS_IOMAP_ALLOC_ENTER, ip, offset, count);
 206                 lockmode = XFS_ILOCK_SHARED;
 207                 bmapi_flags = XFS_BMAPI_ENTIRE;
 208
 209                 /* Attempt non-blocking lock */
 210                 if (flags & BMAPI_TRYLOCK) {
 211                         if (!xfs_ilock_nowait(ip, lockmode))
 212                                 return XFS_ERROR(EAGAIN);
 213                 } else {
 214                         xfs_ilock(ip, lockmode);
 215                 }
 216                 break;
 217         default:
 218                 BUG();
 219         }
 220
 221         ASSERT(offset <= mp->m_maxioffset);
 222         if ((xfs_fsize_t)offset + count > mp->m_maxioffset)
 223                 count = mp->m_maxioffset - offset;
 224         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 225         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 226
 227         error = xfs_bmapi(NULL, ip, offset_fsb,
 228                         (xfs_filblks_t)(end_fsb - offset_fsb),
 229                         bmapi_flags,  NULL, 0, &imap,
 230                         &nimaps, NULL, NULL);
 231
 232         if (error)
 233                 goto out;
 234
 235         switch (flags & (BMAPI_WRITE|BMAPI_ALLOCATE)) {
 236         case BMAPI_WRITE:
 237                 /* If we found an extent, return it */
 238                 if (nimaps &&
 239                     (imap.br_startblock != HOLESTARTBLOCK) &&
 240                     (imap.br_startblock != DELAYSTARTBLOCK)) {
 241                         xfs_iomap_map_trace(XFS_IOMAP_WRITE_MAP, ip,
 242                                         offset, count, iomapp, &imap, flags);
 243                         break;
 244                 }
 245
 246                 if (flags & (BMAPI_DIRECT|BMAPI_MMAP)) {
 247                         error = xfs_iomap_write_direct(ip, offset, count, flags,
 248                                                        &imap, &nimaps, nimaps);
 249                 } else {
 250                         error = xfs_iomap_write_delay(ip, offset, count, flags,
 251                                                       &imap, &nimaps);
 252                 }
 253                 if (!error) {
 254                         xfs_iomap_map_trace(XFS_IOMAP_ALLOC_MAP, ip,
 255                                         offset, count, iomapp, &imap, flags);
 256                 }
 257                 iomap_flags = IOMAP_NEW;
 258                 break;
 259         case BMAPI_ALLOCATE:
 260                 /* If we found an extent, return it */
 261                 xfs_iunlock(ip, lockmode);
 262                 lockmode = 0;
 263
 264                 if (nimaps && !isnullstartblock(imap.br_startblock)) {
 265                         xfs_iomap_map_trace(XFS_IOMAP_WRITE_MAP, ip,
 266                                         offset, count, iomapp, &imap, flags);
 267                         break;
 268                 }
 269
 270                 error = xfs_iomap_write_allocate(ip, offset, count,
 271                                                  &imap, &nimaps);
 272                 break;
 273         }
 274
 275         if (nimaps) {
 276                 *niomaps = xfs_imap_to_bmap(ip, offset, &imap,
 277                                             iomapp, nimaps, *niomaps, iomap_flags);
 278         } else if (niomaps) {
 279                 *niomaps = 0;
 280         }
 281
 282 out:
 283         if (lockmode)
 284                 xfs_iunlock(ip, lockmode);
 285         return XFS_ERROR(error);
 286 }
 287
 288
 289 STATIC int
 290 xfs_iomap_eof_align_last_fsb(
 291         xfs_mount_t     *mp,
 292         xfs_inode_t     *ip,
 293         xfs_extlen_t    extsize,
 294         xfs_fileoff_t   *last_fsb)
 295 {
 296         xfs_fileoff_t   new_last_fsb = 0;
 297         xfs_extlen_t    align;
 298         int             eof, error;
 299
 300         if (XFS_IS_REALTIME_INODE(ip))
 301                 ;
 302         /*
 303          * If mounted with the "-o swalloc" option, roundup the allocation
 304          * request to a stripe width boundary if the file size is >=
 305          * stripe width and we are allocating past the allocation eof.
 306          */
 307         else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
 308                 (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
 309                 new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
 310         /*
 311          * Roundup the allocation request to a stripe unit (m_dalign) boundary
 312          * if the file size is >= stripe unit size, and we are allocating past
 313          * the allocation eof.
 314          */
 315         else if (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
 316                 new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
 317
 318         /*
 319          * Always round up the allocation request to an extent boundary
 320          * (when file on a real-time subvolume or has di_extsize hint).
 321          */
 322         if (extsize) {
 323                 if (new_last_fsb)
 324                         align = roundup_64(new_last_fsb, extsize);
 325                 else
 326                         align = extsize;
 327                 new_last_fsb = roundup_64(*last_fsb, align);
 328         }
 329
 330         if (new_last_fsb) {
 331                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 332                 if (error)
 333                         return error;
 334                 if (eof)
 335                         *last_fsb = new_last_fsb;
 336         }
 337         return 0;
 338 }
 339
 340 STATIC int
 341 xfs_flush_space(
 342         xfs_inode_t     *ip,
 343         int             *fsynced,
 344         int             *ioflags)
 345 {
 346         switch (*fsynced) {
 347         case 0:
 348                 if (ip->i_delayed_blks) {
 349                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 350                         xfs_flush_inode(ip);
 351                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 352                         *fsynced = 1;
 353                 } else {
 354                         *ioflags |= BMAPI_SYNC;
 355                         *fsynced = 2;
 356                 }
 357                 return 0;
 358         case 1:
 359                 *fsynced = 2;
 360                 *ioflags |= BMAPI_SYNC;
 361                 return 0;
 362         case 2:
 363                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 364                 xfs_flush_device(ip);
 365                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 366                 *fsynced = 3;
 367                 return 0;
 368         }
 369         return 1;
 370 }
 371
 372 STATIC int
 373 xfs_cmn_err_fsblock_zero(
 374         xfs_inode_t     *ip,
 375         xfs_bmbt_irec_t *imap)
 376 {
 377         xfs_cmn_err(XFS_PTAG_FSBLOCK_ZERO, CE_ALERT, ip->i_mount,
 378                         "Access to block zero in inode %llu "
 379                         "start_block: %llx start_off: %llx "
 380                         "blkcnt: %llx extent-state: %x\n",
 381                 (unsigned long long)ip->i_ino,
 382                 (unsigned long long)imap->br_startblock,
 383                 (unsigned long long)imap->br_startoff,
 384                 (unsigned long long)imap->br_blockcount,
 385                 imap->br_state);
 386         return EFSCORRUPTED;
 387 }
 388
 389 int
 390 xfs_iomap_write_direct(
 391         xfs_inode_t     *ip,
 392         xfs_off_t       offset,
 393         size_t          count,
 394         int             flags,
 395         xfs_bmbt_irec_t *ret_imap,
 396         int             *nmaps,
 397         int             found)
 398 {
 399         xfs_mount_t     *mp = ip->i_mount;
 400         xfs_fileoff_t   offset_fsb;
 401         xfs_fileoff_t   last_fsb;
 402         xfs_filblks_t   count_fsb, resaligned;
 403         xfs_fsblock_t   firstfsb;
 404         xfs_extlen_t    extsz, temp;
 405         int             nimaps;
 406         int             bmapi_flag;
 407         int             quota_flag;
 408         int             rt;
 409         xfs_trans_t     *tp;
 410         xfs_bmbt_irec_t imap;
 411         xfs_bmap_free_t free_list;
 412         uint            qblocks, resblks, resrtextents;
 413         int             committed;
 414         int             error;
 415
 416         /*
 417          * Make sure that the dquots are there. This doesn't hold
 418          * the ilock across a disk read.
 419          */
 420         error = XFS_QM_DQATTACH(ip->i_mount, ip, XFS_QMOPT_ILOCKED);
 421         if (error)
 422                 return XFS_ERROR(error);
 423
 424         rt = XFS_IS_REALTIME_INODE(ip);
 425         extsz = xfs_get_extsz_hint(ip);
 426
 427         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 428         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 429         if ((offset + count) > ip->i_size) {
 430                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 431                 if (error)
 432                         goto error_out;
 433         } else {
 434                 if (found && (ret_imap->br_startblock == HOLESTARTBLOCK))
 435                         last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 436                                         ret_imap->br_blockcount +
 437                                         ret_imap->br_startoff);
 438         }
 439         count_fsb = last_fsb - offset_fsb;
 440         ASSERT(count_fsb > 0);
 441
 442         resaligned = count_fsb;
 443         if (unlikely(extsz)) {
 444                 if ((temp = do_mod(offset_fsb, extsz)))
 445                         resaligned += temp;
 446                 if ((temp = do_mod(resaligned, extsz)))
 447                         resaligned += extsz - temp;
 448         }
 449
 450         if (unlikely(rt)) {
 451                 resrtextents = qblocks = resaligned;
 452                 resrtextents /= mp->m_sb.sb_rextsize;
 453                 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 454                 quota_flag = XFS_QMOPT_RES_RTBLKS;
 455         } else {
 456                 resrtextents = 0;
 457                 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 458                 quota_flag = XFS_QMOPT_RES_REGBLKS;
 459         }
 460
 461         /*
 462          * Allocate and setup the transaction
 463          */
 464         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 465         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 466         error = xfs_trans_reserve(tp, resblks,
 467                         XFS_WRITE_LOG_RES(mp), resrtextents,
 468                         XFS_TRANS_PERM_LOG_RES,
 469                         XFS_WRITE_LOG_COUNT);
 470         /*
 471          * Check for running out of space, note: need lock to return
 472          */
 473         if (error)
 474                 xfs_trans_cancel(tp, 0);
 475         xfs_ilock(ip, XFS_ILOCK_EXCL);
 476         if (error)
 477                 goto error_out;
 478
 479         error = XFS_TRANS_RESERVE_QUOTA_NBLKS(mp, tp, ip,
 480                                               qblocks, 0, quota_flag);
 481         if (error)
 482                 goto error1;
 483
 484         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 485         xfs_trans_ihold(tp, ip);
 486
 487         bmapi_flag = XFS_BMAPI_WRITE;
 488         if ((flags & BMAPI_DIRECT) && (offset < ip->i_size || extsz))
 489                 bmapi_flag |= XFS_BMAPI_PREALLOC;
 490
 491         /*
 492          * Issue the xfs_bmapi() call to allocate the blocks
 493          */
 494         xfs_bmap_init(&free_list, &firstfsb);
 495         nimaps = 1;
 496         error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 497                 &firstfsb, 0, &imap, &nimaps, &free_list, NULL);
 498         if (error)
 499                 goto error0;
 500
 501         /*
 502          * Complete the transaction
 503          */
 504         error = xfs_bmap_finish(&tp, &free_list, &committed);
 505         if (error)
 506                 goto error0;
 507         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 508         if (error)
 509                 goto error_out;
 510
 511         /*
 512          * Copy any maps to caller's array and return any error.
 513          */
 514         if (nimaps == 0) {
 515                 error = ENOSPC;
 516                 goto error_out;
 517         }
 518
 519         if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) {
 520                 error = xfs_cmn_err_fsblock_zero(ip, &imap);
 521                 goto error_out;
 522         }
 523
 524         *ret_imap = imap;
 525         *nmaps = 1;
 526         return 0;
 527
 528 error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
 529         xfs_bmap_cancel(&free_list);
 530         XFS_TRANS_UNRESERVE_QUOTA_NBLKS(mp, tp, ip, qblocks, 0, quota_flag);
 531
 532 error1: /* Just cancel transaction */
 533         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 534         *nmaps = 0;     /* nothing set-up here */
 535
 536 error_out:
 537         return XFS_ERROR(error);
 538 }
 539
 540 /*
 541  * If the caller is doing a write at the end of the file,
 542  * then extend the allocation out to the file system's write
 543  * iosize.  We clean up any extra space left over when the
 544  * file is closed in xfs_inactive().
 545  *
 546  * For sync writes, we are flushing delayed allocate space to
 547  * try to make additional space available for allocation near
 548  * the filesystem full boundary - preallocation hurts in that
 549  * situation, of course.
 550  */
 551 STATIC int
 552 xfs_iomap_eof_want_preallocate(
 553         xfs_mount_t     *mp,
 554         xfs_inode_t     *ip,
 555         xfs_off_t       offset,
 556         size_t          count,
 557         int             ioflag,
 558         xfs_bmbt_irec_t *imap,
 559         int             nimaps,
 560         int             *prealloc)
 561 {
 562         xfs_fileoff_t   start_fsb;
 563         xfs_filblks_t   count_fsb;
 564         xfs_fsblock_t   firstblock;
 565         int             n, error, imaps;
 566
 567         *prealloc = 0;
 568         if ((ioflag & BMAPI_SYNC) || (offset + count) <= ip->i_size)
 569                 return 0;
 570
 571         /*
 572          * If there are any real blocks past eof, then don't
 573          * do any speculative allocation.
 574          */
 575         start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 576         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
 577         while (count_fsb > 0) {
 578                 imaps = nimaps;
 579                 firstblock = NULLFSBLOCK;
 580                 error = xfs_bmapi(NULL, ip, start_fsb, count_fsb, 0,
 581                                   &firstblock, 0, imap, &imaps, NULL, NULL);
 582                 if (error)
 583                         return error;
 584                 for (n = 0; n < imaps; n++) {
 585                         if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 586                             (imap[n].br_startblock != DELAYSTARTBLOCK))
 587                                 return 0;
 588                         start_fsb += imap[n].br_blockcount;
 589                         count_fsb -= imap[n].br_blockcount;
 590                 }
 591         }
 592         *prealloc = 1;
 593         return 0;
 594 }
 595
 596 int
 597 xfs_iomap_write_delay(
 598         xfs_inode_t     *ip,
 599         xfs_off_t       offset,
 600         size_t          count,
 601         int             ioflag,
 602         xfs_bmbt_irec_t *ret_imap,
 603         int             *nmaps)
 604 {
 605         xfs_mount_t     *mp = ip->i_mount;
 606         xfs_fileoff_t   offset_fsb;
 607         xfs_fileoff_t   last_fsb;
 608         xfs_off_t       aligned_offset;
 609         xfs_fileoff_t   ioalign;
 610         xfs_fsblock_t   firstblock;
 611         xfs_extlen_t    extsz;
 612         int             nimaps;
 613         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 614         int             prealloc, fsynced = 0;
 615         int             error;
 616
 617         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 618
 619         /*
 620          * Make sure that the dquots are there. This doesn't hold
 621          * the ilock across a disk read.
 622          */
 623         error = XFS_QM_DQATTACH(mp, ip, XFS_QMOPT_ILOCKED);
 624         if (error)
 625                 return XFS_ERROR(error);
 626
 627         extsz = xfs_get_extsz_hint(ip);
 628         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 629
 630 retry:
 631         error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 632                                 ioflag, imap, XFS_WRITE_IMAPS, &prealloc);
 633         if (error)
 634                 return error;
 635
 636         if (prealloc) {
 637                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 638                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 639                 last_fsb = ioalign + mp->m_writeio_blocks;
 640         } else {
 641                 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 642         }
 643
 644         if (prealloc || extsz) {
 645                 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 646                 if (error)
 647                         return error;
 648         }
 649
 650         nimaps = XFS_WRITE_IMAPS;
 651         firstblock = NULLFSBLOCK;
 652         error = xfs_bmapi(NULL, ip, offset_fsb,
 653                           (xfs_filblks_t)(last_fsb - offset_fsb),
 654                           XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
 655                           XFS_BMAPI_ENTIRE, &firstblock, 1, imap,
 656                           &nimaps, NULL, NULL);
 657         if (error && (error != ENOSPC))
 658                 return XFS_ERROR(error);
 659
 660         /*
 661          * If bmapi returned us nothing, and if we didn't get back EDQUOT,
 662          * then we must have run out of space - flush delalloc, and retry..
 663          */
 664         if (nimaps == 0) {
 665                 xfs_iomap_enter_trace(XFS_IOMAP_WRITE_NOSPACE,
 666                                         ip, offset, count);
 667                 if (xfs_flush_space(ip, &fsynced, &ioflag))
 668                         return XFS_ERROR(ENOSPC);
 669
 670                 error = 0;
 671                 goto retry;
 672         }
 673
 674         if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 675                 return xfs_cmn_err_fsblock_zero(ip, &imap[0]);
 676
 677         *ret_imap = imap[0];
 678         *nmaps = 1;
 679
 680         return 0;
 681 }
 682
 683 /*
 684  * Pass in a delayed allocate extent, convert it to real extents;
 685  * return to the caller the extent we create which maps on top of
 686  * the originating callers request.
 687  *
 688  * Called without a lock on the inode.
 689  *
 690  * We no longer bother to look at the incoming map - all we have to
 691  * guarantee is that whatever we allocate fills the required range.
 692  */
 693 int
 694 xfs_iomap_write_allocate(
 695         xfs_inode_t     *ip,
 696         xfs_off_t       offset,
 697         size_t          count,
 698         xfs_bmbt_irec_t *map,
 699         int             *retmap)
 700 {
 701         xfs_mount_t     *mp = ip->i_mount;
 702         xfs_fileoff_t   offset_fsb, last_block;
 703         xfs_fileoff_t   end_fsb, map_start_fsb;
 704         xfs_fsblock_t   first_block;
 705         xfs_bmap_free_t free_list;
 706         xfs_filblks_t   count_fsb;
 707         xfs_bmbt_irec_t imap;
 708         xfs_trans_t     *tp;
 709         int             nimaps, committed;
 710         int             error = 0;
 711         int             nres;
 712
 713         *retmap = 0;
 714
 715         /*
 716          * Make sure that the dquots are there.
 717          */
 718         if ((error = XFS_QM_DQATTACH(mp, ip, 0)))
 719                 return XFS_ERROR(error);
 720
 721         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 722         count_fsb = map->br_blockcount;
 723         map_start_fsb = map->br_startoff;
 724
 725         XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 726
 727         while (count_fsb != 0) {
 728                 /*
 729                  * Set up a transaction with which to allocate the
 730                  * backing store for the file.  Do allocations in a
 731                  * loop until we get some space in the range we are
 732                  * interested in.  The other space that might be allocated
 733                  * is in the delayed allocation extent on which we sit
 734                  * but before our buffer starts.
 735                  */
 736
 737                 nimaps = 0;
 738                 while (nimaps == 0) {
 739                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 740                         tp->t_flags |= XFS_TRANS_RESERVE;
 741                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 742                         error = xfs_trans_reserve(tp, nres,
 743                                         XFS_WRITE_LOG_RES(mp),
 744                                         0, XFS_TRANS_PERM_LOG_RES,
 745                                         XFS_WRITE_LOG_COUNT);
 746                         if (error) {
 747                                 xfs_trans_cancel(tp, 0);
 748                                 return XFS_ERROR(error);
 749                         }
 750                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 751                         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 752                         xfs_trans_ihold(tp, ip);
 753
 754                         xfs_bmap_init(&free_list, &first_block);
 755
 756                         /*
 757                          * it is possible that the extents have changed since
 758                          * we did the read call as we dropped the ilock for a
 759                          * while. We have to be careful about truncates or hole
 760                          * punchs here - we are not allowed to allocate
 761                          * non-delalloc blocks here.
 762                          *
 763                          * The only protection against truncation is the pages
 764                          * for the range we are being asked to convert are
 765                          * locked and hence a truncate will block on them
 766                          * first.
 767                          *
 768                          * As a result, if we go beyond the range we really
 769                          * need and hit an delalloc extent boundary followed by
 770                          * a hole while we have excess blocks in the map, we
 771                          * will fill the hole incorrectly and overrun the
 772                          * transaction reservation.
 773                          *
 774                          * Using a single map prevents this as we are forced to
 775                          * check each map we look for overlap with the desired
 776                          * range and abort as soon as we find it. Also, given
 777                          * that we only return a single map, having one beyond
 778                          * what we can return is probably a bit silly.
 779                          *
 780                          * We also need to check that we don't go beyond EOF;
 781                          * this is a truncate optimisation as a truncate sets
 782                          * the new file size before block on the pages we
 783                          * currently have locked under writeback. Because they
 784                          * are about to be tossed, we don't need to write them
 785                          * back....
 786                          */
 787                         nimaps = 1;
 788                         end_fsb = XFS_B_TO_FSB(mp, ip->i_size);
 789                         error = xfs_bmap_last_offset(NULL, ip, &last_block,
 790                                                         XFS_DATA_FORK);
 791                         if (error)
 792                                 goto trans_cancel;
 793
 794                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 795                         if ((map_start_fsb + count_fsb) > last_block) {
 796                                 count_fsb = last_block - map_start_fsb;
 797                                 if (count_fsb == 0) {
 798                                         error = EAGAIN;
 799                                         goto trans_cancel;
 800                                 }
 801                         }
 802
 803                         /* Go get the actual blocks */
 804                         error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
 805                                         XFS_BMAPI_WRITE, &first_block, 1,
 806                                         &imap, &nimaps, &free_list, NULL);
 807                         if (error)
 808                                 goto trans_cancel;
 809
 810                         error = xfs_bmap_finish(&tp, &free_list, &committed);
 811                         if (error)
 812                                 goto trans_cancel;
 813
 814                         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 815                         if (error)
 816                                 goto error0;
 817
 818                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 819                 }
 820
 821                 /*
 822                  * See if we were able to allocate an extent that
 823                  * covers at least part of the callers request
 824                  */
 825                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 826                         return xfs_cmn_err_fsblock_zero(ip, &imap);
 827
 828                 if ((offset_fsb >= imap.br_startoff) &&
 829                     (offset_fsb < (imap.br_startoff +
 830                                    imap.br_blockcount))) {
 831                         *map = imap;
 832                         *retmap = 1;
 833                         XFS_STATS_INC(xs_xstrat_quick);
 834                         return 0;
 835                 }
 836
 837                 /*
 838                  * So far we have not mapped the requested part of the
 839                  * file, just surrounding data, try again.
 840                  */
 841                 count_fsb -= imap.br_blockcount;
 842                 map_start_fsb = imap.br_startoff + imap.br_blockcount;
 843         }
 844
 845 trans_cancel:
 846         xfs_bmap_cancel(&free_list);
 847         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 848 error0:
 849         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 850         return XFS_ERROR(error);
 851 }
 852
 853 int
 854 xfs_iomap_write_unwritten(
 855         xfs_inode_t     *ip,
 856         xfs_off_t       offset,
 857         size_t          count)
 858 {
 859         xfs_mount_t     *mp = ip->i_mount;
 860         xfs_fileoff_t   offset_fsb;
 861         xfs_filblks_t   count_fsb;
 862         xfs_filblks_t   numblks_fsb;
 863         xfs_fsblock_t   firstfsb;
 864         int             nimaps;
 865         xfs_trans_t     *tp;
 866         xfs_bmbt_irec_t imap;
 867         xfs_bmap_free_t free_list;
 868         uint            resblks;
 869         int             committed;
 870         int             error;
 871
 872         xfs_iomap_enter_trace(XFS_IOMAP_UNWRITTEN, ip, offset, count);
 873
 874         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 875         count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 876         count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 877
 878         /*
 879          * Reserve enough blocks in this transaction for two complete extent
 880          * btree splits.  We may be converting the middle part of an unwritten
 881          * extent and in this case we will insert two new extents in the btree
 882          * each of which could cause a full split.
 883          *
 884          * This reservation amount will be used in the first call to
 885          * xfs_bmbt_split() to select an AG with enough space to satisfy the
 886          * rest of the operation.
 887          */
 888         resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 889
 890         do {
 891                 /*
 892                  * set up a transaction to convert the range of extents
 893                  * from unwritten to real. Do allocations in a loop until
 894                  * we have covered the range passed in.
 895                  */
 896                 tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 897                 tp->t_flags |= XFS_TRANS_RESERVE;
 898                 error = xfs_trans_reserve(tp, resblks,
 899                                 XFS_WRITE_LOG_RES(mp), 0,
 900                                 XFS_TRANS_PERM_LOG_RES,
 901                                 XFS_WRITE_LOG_COUNT);
 902                 if (error) {
 903                         xfs_trans_cancel(tp, 0);
 904                         return XFS_ERROR(error);
 905                 }
 906
 907                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 908                 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 909                 xfs_trans_ihold(tp, ip);
 910
 911                 /*
 912                  * Modify the unwritten extent state of the buffer.
 913                  */
 914                 xfs_bmap_init(&free_list, &firstfsb);
 915                 nimaps = 1;
 916                 error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
 917                                   XFS_BMAPI_WRITE|XFS_BMAPI_CONVERT, &firstfsb,
 918                                   1, &imap, &nimaps, &free_list, NULL);
 919                 if (error)
 920                         goto error_on_bmapi_transaction;
 921
 922                 error = xfs_bmap_finish(&(tp), &(free_list), &committed);
 923                 if (error)
 924                         goto error_on_bmapi_transaction;
 925
 926                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 927                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 928                 if (error)
 929                         return XFS_ERROR(error);
 930
 931                 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 932                         return xfs_cmn_err_fsblock_zero(ip, &imap);
 933
 934                 if ((numblks_fsb = imap.br_blockcount) == 0) {
 935                         /*
 936                          * The numblks_fsb value should always get
 937                          * smaller, otherwise the loop is stuck.
 938                          */
 939                         ASSERT(imap.br_blockcount);
 940                         break;
 941                 }
 942                 offset_fsb += numblks_fsb;
 943                 count_fsb -= numblks_fsb;
 944         } while (count_fsb > 0);
 945
 946         return 0;
 947
 948 error_on_bmapi_transaction:
 949         xfs_bmap_cancel(&free_list);
 950         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 951         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 952         return XFS_ERROR(error);
 953 }