fs/xfs/linux/xfs_iomap.c

   1 /*
   2  * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32
  33 #include "xfs.h"
  34
  35 #include "xfs_fs.h"
  36 #include "xfs_inum.h"
  37 #include "xfs_log.h"
  38 #include "xfs_trans.h"
  39 #include "xfs_sb.h"
  40 #include "xfs_ag.h"
  41 #include "xfs_dir.h"
  42 #include "xfs_dir2.h"
  43 #include "xfs_alloc.h"
  44 #include "xfs_dmapi.h"
  45 #include "xfs_quota.h"
  46 #include "xfs_mount.h"
  47 #include "xfs_alloc_btree.h"
  48 #include "xfs_bmap_btree.h"
  49 #include "xfs_ialloc_btree.h"
  50 #include "xfs_btree.h"
  51 #include "xfs_ialloc.h"
  52 #include "xfs_attr_sf.h"
  53 #include "xfs_dir_sf.h"
  54 #include "xfs_dir2_sf.h"
  55 #include "xfs_dinode.h"
  56 #include "xfs_inode.h"
  57 #include "xfs_bmap.h"
  58 #include "xfs_bit.h"
  59 #include "xfs_rtalloc.h"
  60 #include "xfs_error.h"
  61 #include "xfs_itable.h"
  62 #include "xfs_rw.h"
  63 #include "xfs_acl.h"
  64 #include "xfs_cap.h"
  65 #include "xfs_mac.h"
  66 #include "xfs_attr.h"
  67 #include "xfs_buf_item.h"
  68 #include "xfs_trans_space.h"
  69 #include "xfs_utils.h"
  70
  71 #define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
  72                                                 << mp->m_writeio_log)
  73 #define XFS_STRAT_WRITE_IMAPS   2
  74 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  75
  76 STATIC int
  77 _xfs_imap_to_bmap(
  78         xfs_iocore_t    *io,
  79         xfs_off_t       offset,
  80         int             new,
  81         xfs_bmbt_irec_t *imap,
  82         page_buf_bmap_t *pbmapp,
  83         int             imaps,                  /* Number of imap entries */
  84         int             pbmaps)                 /* Number of pbmap entries */
  85 {
  86         xfs_mount_t     *mp;
  87         xfs_fsize_t     nisize;
  88         int             pbm;
  89         xfs_fsblock_t   start_block;
  90
  91         mp = io->io_mount;
  92         nisize = XFS_SIZE(mp, io);
  93         if (io->io_new_size > nisize)
  94                 nisize = io->io_new_size;
  95
  96         for (pbm = 0; imaps && pbm < pbmaps; imaps--, pbmapp++, imap++, pbm++) {
  97                 pbmapp->pbm_target = io->io_flags & XFS_IOCORE_RT ?
  98                         mp->m_rtdev_targp : mp->m_ddev_targp;
  99                 pbmapp->pbm_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
 100                 pbmapp->pbm_delta = offset - pbmapp->pbm_offset;
 101                 pbmapp->pbm_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
 102                 pbmapp->pbm_flags = 0;
 103
 104                 start_block = imap->br_startblock;
 105                 if (start_block == HOLESTARTBLOCK) {
 106                         pbmapp->pbm_bn = PAGE_BUF_DADDR_NULL;
 107                         pbmapp->pbm_flags = PBMF_HOLE;
 108                 } else if (start_block == DELAYSTARTBLOCK) {
 109                         pbmapp->pbm_bn = PAGE_BUF_DADDR_NULL;
 110                         pbmapp->pbm_flags = PBMF_DELAY;
 111                 } else {
 112                         pbmapp->pbm_bn = XFS_FSB_TO_DB_IO(io, start_block);
 113                         if (ISUNWRITTEN(imap))
 114                                 pbmapp->pbm_flags |= PBMF_UNWRITTEN;
 115                 }
 116
 117                 if ((pbmapp->pbm_offset + pbmapp->pbm_bsize) >= nisize) {
 118                         pbmapp->pbm_flags |= PBMF_EOF;
 119                 }
 120
 121                 if (new)
 122                         pbmapp->pbm_flags |= PBMF_NEW;
 123
 124                 offset += pbmapp->pbm_bsize - pbmapp->pbm_delta;
 125         }
 126         return pbm;     /* Return the number filled */
 127 }
 128
 129 int
 130 xfs_iomap(
 131         xfs_iocore_t    *io,
 132         xfs_off_t       offset,
 133         ssize_t         count,
 134         int             flags,
 135         page_buf_bmap_t *pbmapp,
 136         int             *npbmaps)
 137 {
 138         xfs_mount_t     *mp = io->io_mount;
 139         xfs_fileoff_t   offset_fsb, end_fsb;
 140         int             error = 0;
 141         int             new = 0;
 142         int             lockmode = 0;
 143         xfs_bmbt_irec_t imap;
 144         int             nimaps = 1;
 145         int             bmap_flags = 0;
 146
 147         if (XFS_FORCED_SHUTDOWN(mp))
 148                 return -XFS_ERROR(EIO);
 149
 150         switch (flags &
 151                 (BMAP_READ | BMAP_WRITE | BMAP_ALLOCATE |
 152                  BMAP_UNWRITTEN | BMAP_DEVICE)) {
 153         case BMAP_READ:
 154                 lockmode = XFS_LCK_MAP_SHARED(mp, io);
 155                 bmap_flags = XFS_BMAPI_ENTIRE;
 156                 if (flags & BMAP_IGNSTATE)
 157                         bmap_flags |= XFS_BMAPI_IGSTATE;
 158                 break;
 159         case PBF_WRITE:
 160                 lockmode = XFS_ILOCK_EXCL|XFS_EXTSIZE_WR;
 161                 bmap_flags = 0;
 162                 XFS_ILOCK(mp, io, lockmode);
 163                 break;
 164         case BMAP_ALLOCATE:
 165                 lockmode = XFS_ILOCK_SHARED|XFS_EXTSIZE_RD;
 166                 bmap_flags = XFS_BMAPI_ENTIRE;
 167                 /* Attempt non-blocking lock */
 168                 if (flags & BMAP_TRYLOCK) {
 169                         if (!XFS_ILOCK_NOWAIT(mp, io, lockmode))
 170                                 return XFS_ERROR(EAGAIN);
 171                 } else {
 172                         XFS_ILOCK(mp, io, lockmode);
 173                 }
 174                 break;
 175         case BMAP_UNWRITTEN:
 176                 goto phase2;
 177         case BMAP_DEVICE:
 178                 lockmode = XFS_LCK_MAP_SHARED(mp, io);
 179                 pbmapp->pbm_target = io->io_flags & XFS_IOCORE_RT ?
 180                         mp->m_rtdev_targp : mp->m_ddev_targp;
 181                 error = 0;
 182                 *npbmaps = 1;
 183                 goto out;
 184         default:
 185                 BUG();
 186         }
 187
 188         ASSERT(offset <= mp->m_maxioffset);
 189         if ((xfs_fsize_t)offset + count > mp->m_maxioffset)
 190                 count = mp->m_maxioffset - offset;
 191         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 192         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 193
 194         error = XFS_BMAPI(mp, NULL, io, offset_fsb,
 195                         (xfs_filblks_t)(end_fsb - offset_fsb) ,
 196                         bmap_flags,  NULL, 0, &imap,
 197                         &nimaps, NULL);
 198
 199         if (error)
 200                 goto out;
 201
 202 phase2:
 203         switch (flags & (BMAP_WRITE|BMAP_ALLOCATE|BMAP_UNWRITTEN)) {
 204         case BMAP_WRITE:
 205                 /* If we found an extent, return it */
 206                 if (nimaps && (imap.br_startblock != HOLESTARTBLOCK))
 207                         break;
 208
 209                 if (flags & (BMAP_DIRECT|BMAP_MMAP)) {
 210                         error = XFS_IOMAP_WRITE_DIRECT(mp, io, offset,
 211                                         count, flags, &imap, &nimaps, nimaps);
 212                 } else {
 213                         error = XFS_IOMAP_WRITE_DELAY(mp, io, offset, count,
 214                                         flags, &imap, &nimaps);
 215                 }
 216                 new = 1;
 217                 break;
 218         case BMAP_ALLOCATE:
 219                 /* If we found an extent, return it */
 220                 XFS_IUNLOCK(mp, io, lockmode);
 221                 lockmode = 0;
 222
 223                 if (nimaps && !ISNULLSTARTBLOCK(imap.br_startblock))
 224                         break;
 225
 226                 error = XFS_IOMAP_WRITE_ALLOCATE(mp, io, &imap, &nimaps);
 227                 break;
 228         case BMAP_UNWRITTEN:
 229                 lockmode = 0;
 230                 error = XFS_IOMAP_WRITE_UNWRITTEN(mp, io, offset, count);
 231                 nimaps = 0;
 232                 break;
 233         }
 234
 235         if (nimaps) {
 236                 *npbmaps = _xfs_imap_to_bmap(io, offset, new, &imap,
 237                                         pbmapp, nimaps, *npbmaps);
 238         } else if (npbmaps) {
 239                 *npbmaps = 0;
 240         }
 241
 242 out:
 243         if (lockmode)
 244                 XFS_IUNLOCK(mp, io, lockmode);
 245         return XFS_ERROR(error);
 246 }
 247
 248 STATIC int
 249 xfs_flush_space(
 250         xfs_inode_t     *ip,
 251         int             *fsynced,
 252         int             *ioflags)
 253 {
 254         vnode_t         *vp = XFS_ITOV(ip);
 255
 256         switch (*fsynced) {
 257         case 0:
 258                 if (ip->i_delayed_blks) {
 259                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 260                         filemap_fdatawrite(LINVFS_GET_IP(vp)->i_mapping);
 261                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 262                         *fsynced = 1;
 263                 } else {
 264                         *ioflags |= BMAP_SYNC;
 265                         *fsynced = 2;
 266                 }
 267                 return 0;
 268         case 1:
 269                 *fsynced = 2;
 270                 *ioflags |= BMAP_SYNC;
 271                 return 0;
 272         case 2:
 273                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 274                 sync_blockdev(vp->v_vfsp->vfs_super->s_bdev);
 275                 xfs_log_force(ip->i_mount, (xfs_lsn_t)0,
 276                                                 XFS_LOG_FORCE|XFS_LOG_SYNC);
 277                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 278                 *fsynced = 3;
 279                 return 0;
 280         }
 281         return 1;
 282 }
 283
 284 int
 285 xfs_iomap_write_direct(
 286         xfs_inode_t     *ip,
 287         loff_t          offset,
 288         size_t          count,
 289         int             flags,
 290         xfs_bmbt_irec_t *ret_imap,
 291         int             *nmaps,
 292         int             found)
 293 {
 294         xfs_mount_t     *mp = ip->i_mount;
 295         xfs_iocore_t    *io = &ip->i_iocore;
 296         xfs_fileoff_t   offset_fsb;
 297         xfs_fileoff_t   last_fsb;
 298         xfs_filblks_t   count_fsb;
 299         xfs_fsize_t     isize;
 300         xfs_fsblock_t   firstfsb;
 301         int             nimaps, maps;
 302         int             error;
 303         int             bmapi_flag;
 304         int             rt;
 305         xfs_trans_t     *tp;
 306         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS], *imapp;
 307         xfs_bmap_free_t free_list;
 308         int             aeof;
 309         xfs_filblks_t   datablocks;
 310         int             committed;
 311         int             numrtextents;
 312         uint            resblks;
 313
 314         /*
 315          * Make sure that the dquots are there. This doesn't hold
 316          * the ilock across a disk read.
 317          */
 318
 319         error = XFS_QM_DQATTACH(ip->i_mount, ip, XFS_QMOPT_ILOCKED);
 320         if (error)
 321                 return XFS_ERROR(error);
 322
 323         maps = min(XFS_WRITE_IMAPS, *nmaps);
 324         nimaps = maps;
 325
 326         isize = ip->i_d.di_size;
 327         aeof = (offset + count) > isize;
 328
 329         if (io->io_new_size > isize)
 330                 isize = io->io_new_size;
 331
 332         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 333         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 334         count_fsb = last_fsb - offset_fsb;
 335         if (found && (ret_imap->br_startblock == HOLESTARTBLOCK)) {
 336                 xfs_fileoff_t   map_last_fsb;
 337
 338                 map_last_fsb = ret_imap->br_blockcount + ret_imap->br_startoff;
 339
 340                 if (map_last_fsb < last_fsb) {
 341                         last_fsb = map_last_fsb;
 342                         count_fsb = last_fsb - offset_fsb;
 343                 }
 344                 ASSERT(count_fsb > 0);
 345         }
 346
 347         /*
 348          * determine if reserving space on
 349          * the data or realtime partition.
 350          */
 351         if ((rt = XFS_IS_REALTIME_INODE(ip))) {
 352                 int     sbrtextsize, iprtextsize;
 353
 354                 sbrtextsize = mp->m_sb.sb_rextsize;
 355                 iprtextsize =
 356                         ip->i_d.di_extsize ? ip->i_d.di_extsize : sbrtextsize;
 357                 numrtextents = (count_fsb + iprtextsize - 1);
 358                 do_div(numrtextents, sbrtextsize);
 359                 datablocks = 0;
 360         } else {
 361                 datablocks = count_fsb;
 362                 numrtextents = 0;
 363         }
 364
 365         /*
 366          * allocate and setup the transaction
 367          */
 368         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 369         tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 370
 371         resblks = XFS_DIOSTRAT_SPACE_RES(mp, datablocks);
 372
 373         error = xfs_trans_reserve(tp, resblks,
 374                         XFS_WRITE_LOG_RES(mp), numrtextents,
 375                         XFS_TRANS_PERM_LOG_RES,
 376                         XFS_WRITE_LOG_COUNT);
 377
 378         /*
 379          * check for running out of space
 380          */
 381         if (error)
 382                 /*
 383                  * Free the transaction structure.
 384                  */
 385                 xfs_trans_cancel(tp, 0);
 386
 387         xfs_ilock(ip, XFS_ILOCK_EXCL);
 388
 389         if (error)
 390                 goto error_out; /* Don't return in above if .. trans ..,
 391                                         need lock to return */
 392
 393         if (XFS_TRANS_RESERVE_BLKQUOTA(mp, tp, ip, resblks)) {
 394                 error = (EDQUOT);
 395                 goto error1;
 396         }
 397         nimaps = 1;
 398
 399         bmapi_flag = XFS_BMAPI_WRITE;
 400         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 401         xfs_trans_ihold(tp, ip);
 402
 403         if (!(flags & BMAP_MMAP) && (offset < ip->i_d.di_size || rt))
 404                 bmapi_flag |= XFS_BMAPI_PREALLOC;
 405
 406         /*
 407          * issue the bmapi() call to allocate the blocks
 408          */
 409         XFS_BMAP_INIT(&free_list, &firstfsb);
 410         imapp = &imap[0];
 411         error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
 412                 bmapi_flag, &firstfsb, 0, imapp, &nimaps, &free_list);
 413         if (error) {
 414                 goto error0;
 415         }
 416
 417         /*
 418          * complete the transaction
 419          */
 420
 421         error = xfs_bmap_finish(&tp, &free_list, firstfsb, &committed);
 422         if (error) {
 423                 goto error0;
 424         }
 425
 426         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES, NULL);
 427         if (error) {
 428                 goto error_out;
 429         }
 430
 431         /* copy any maps to caller's array and return any error. */
 432         if (nimaps == 0) {
 433                 error = (ENOSPC);
 434                 goto error_out;
 435         }
 436
 437         *ret_imap = imap[0];
 438         *nmaps = 1;
 439         return 0;
 440
 441  error0:        /* Cancel bmap, unlock inode, and cancel trans */
 442         xfs_bmap_cancel(&free_list);
 443
 444  error1:        /* Just cancel transaction */
 445         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 446         *nmaps = 0;     /* nothing set-up here */
 447
 448 error_out:
 449         return XFS_ERROR(error);
 450 }
 451
 452 int
 453 xfs_iomap_write_delay(
 454         xfs_inode_t     *ip,
 455         loff_t          offset,
 456         size_t          count,
 457         int             ioflag,
 458         xfs_bmbt_irec_t *ret_imap,
 459         int             *nmaps)
 460 {
 461         xfs_mount_t     *mp = ip->i_mount;
 462         xfs_iocore_t    *io = &ip->i_iocore;
 463         xfs_fileoff_t   offset_fsb;
 464         xfs_fileoff_t   last_fsb;
 465         xfs_fsize_t     isize;
 466         xfs_fsblock_t   firstblock;
 467         int             nimaps;
 468         int             error;
 469         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 470         int             aeof;
 471         int             fsynced = 0;
 472
 473         ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE) != 0);
 474
 475         /*
 476          * Make sure that the dquots are there. This doesn't hold
 477          * the ilock across a disk read.
 478          */
 479
 480         error = XFS_QM_DQATTACH(mp, ip, XFS_QMOPT_ILOCKED);
 481         if (error)
 482                 return XFS_ERROR(error);
 483
 484 retry:
 485         isize = ip->i_d.di_size;
 486         if (io->io_new_size > isize) {
 487                 isize = io->io_new_size;
 488         }
 489
 490         aeof = 0;
 491         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 492         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 493         /*
 494          * If the caller is doing a write at the end of the file,
 495          * then extend the allocation (and the buffer used for the write)
 496          * out to the file system's write iosize.  We clean up any extra
 497          * space left over when the file is closed in xfs_inactive().
 498          *
 499          * We don't bother with this for sync writes, because we need
 500          * to minimize the amount we write for good performance.
 501          */
 502         if (!(ioflag & BMAP_SYNC) && ((offset + count) > ip->i_d.di_size)) {
 503                 xfs_off_t       aligned_offset;
 504                 unsigned int    iosize;
 505                 xfs_fileoff_t   ioalign;
 506
 507                 iosize = mp->m_writeio_blocks;
 508                 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 509                 ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 510                 last_fsb = ioalign + iosize;
 511                 aeof = 1;
 512         }
 513
 514         nimaps = XFS_WRITE_IMAPS;
 515         firstblock = NULLFSBLOCK;
 516
 517         /*
 518          * roundup the allocation request to m_dalign boundary if file size
 519          * is greater that 512K and we are allocating past the allocation eof
 520          */
 521         if (mp->m_dalign && (isize >= mp->m_dalign) && aeof) {
 522                 int eof;
 523                 xfs_fileoff_t new_last_fsb;
 524                 new_last_fsb = roundup_64(last_fsb, mp->m_dalign);
 525                 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 526                 if (error) {
 527                         return error;
 528                 }
 529                 if (eof) {
 530                         last_fsb = new_last_fsb;
 531                 }
 532         }
 533
 534         error = xfs_bmapi(NULL, ip, offset_fsb,
 535                           (xfs_filblks_t)(last_fsb - offset_fsb),
 536                           XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
 537                           XFS_BMAPI_ENTIRE, &firstblock, 1, imap,
 538                           &nimaps, NULL);
 539         /*
 540          * This can be EDQUOT, if nimaps == 0
 541          */
 542         if (error && (error != ENOSPC)) {
 543                 return XFS_ERROR(error);
 544         }
 545         /*
 546          * If bmapi returned us nothing, and if we didn't get back EDQUOT,
 547          * then we must have run out of space.
 548          */
 549
 550         if (nimaps == 0) {
 551                 if (xfs_flush_space(ip, &fsynced, &ioflag))
 552                         return XFS_ERROR(ENOSPC);
 553
 554                 error = 0;
 555                 goto retry;
 556         }
 557
 558         *ret_imap = imap[0];
 559         *nmaps = 1;
 560         return 0;
 561 }
 562
 563 /*
 564  * Pass in a delayed allocate extent, convert it to real extents;
 565  * return to the caller the extent we create which maps on top of
 566  * the originating callers request.
 567  *
 568  * Called without a lock on the inode.
 569  */
 570 int
 571 xfs_iomap_write_allocate(
 572         xfs_inode_t     *ip,
 573         xfs_bmbt_irec_t *map,
 574         int             *retmap)
 575 {
 576         xfs_mount_t     *mp = ip->i_mount;
 577         xfs_fileoff_t   offset_fsb, last_block;
 578         xfs_fileoff_t   end_fsb, map_start_fsb;
 579         xfs_fsblock_t   first_block;
 580         xfs_bmap_free_t free_list;
 581         xfs_filblks_t   count_fsb;
 582         xfs_bmbt_irec_t imap[XFS_STRAT_WRITE_IMAPS];
 583         xfs_trans_t     *tp;
 584         int             i, nimaps, committed;
 585         int             error = 0;
 586         int             nres;
 587
 588         *retmap = 0;
 589
 590         /*
 591          * Make sure that the dquots are there.
 592          */
 593
 594         if ((error = XFS_QM_DQATTACH(mp, ip, 0)))
 595                 return XFS_ERROR(error);
 596
 597         offset_fsb = map->br_startoff;
 598         count_fsb = map->br_blockcount;
 599         map_start_fsb = offset_fsb;
 600
 601         XFS_STATS_ADD(xfsstats.xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 602
 603         while (count_fsb != 0) {
 604                 /*
 605                  * Set up a transaction with which to allocate the
 606                  * backing store for the file.  Do allocations in a
 607                  * loop until we get some space in the range we are
 608                  * interested in.  The other space that might be allocated
 609                  * is in the delayed allocation extent on which we sit
 610                  * but before our buffer starts.
 611                  */
 612
 613                 nimaps = 0;
 614                 while (nimaps == 0) {
 615                         tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 616                         nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 617                         error = xfs_trans_reserve(tp, nres,
 618                                         XFS_WRITE_LOG_RES(mp),
 619                                         0, XFS_TRANS_PERM_LOG_RES,
 620                                         XFS_WRITE_LOG_COUNT);
 621
 622                         if (error == ENOSPC) {
 623                                 error = xfs_trans_reserve(tp, 0,
 624                                                 XFS_WRITE_LOG_RES(mp),
 625                                                 0,
 626                                                 XFS_TRANS_PERM_LOG_RES,
 627                                                 XFS_WRITE_LOG_COUNT);
 628                         }
 629                         if (error) {
 630                                 xfs_trans_cancel(tp, 0);
 631                                 return XFS_ERROR(error);
 632                         }
 633                         xfs_ilock(ip, XFS_ILOCK_EXCL);
 634                         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 635                         xfs_trans_ihold(tp, ip);
 636
 637                         XFS_BMAP_INIT(&free_list, &first_block);
 638
 639                         nimaps = XFS_STRAT_WRITE_IMAPS;
 640                         /*
 641                          * Ensure we don't go beyond eof - it is possible
 642                          * the extents changed since we did the read call,
 643                          * we dropped the ilock in the interim.
 644                          */
 645
 646                         end_fsb = XFS_B_TO_FSB(mp, ip->i_d.di_size);
 647                         xfs_bmap_last_offset(NULL, ip, &last_block,
 648                                 XFS_DATA_FORK);
 649                         last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 650                         if ((map_start_fsb + count_fsb) > last_block) {
 651                                 count_fsb = last_block - map_start_fsb;
 652                                 if (count_fsb == 0) {
 653                                         error = EAGAIN;
 654                                         goto trans_cancel;
 655                                 }
 656                         }
 657
 658                         /* Go get the actual blocks */
 659                         error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
 660                                         XFS_BMAPI_WRITE, &first_block, 1,
 661                                         imap, &nimaps, &free_list);
 662
 663                         if (error)
 664                                 goto trans_cancel;
 665
 666                         error = xfs_bmap_finish(&tp, &free_list,
 667                                         first_block, &committed);
 668
 669                         if (error)
 670                                 goto trans_cancel;
 671
 672                         error = xfs_trans_commit(tp,
 673                                         XFS_TRANS_RELEASE_LOG_RES, NULL);
 674
 675                         if (error)
 676                                 goto error0;
 677
 678                         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 679                 }
 680
 681                 /*
 682                  * See if we were able to allocate an extent that
 683                  * covers at least part of the callers request
 684                  */
 685
 686                 for (i = 0; i < nimaps; i++) {
 687                         if ((map->br_startoff >= imap[i].br_startoff) &&
 688                             (map->br_startoff < (imap[i].br_startoff +
 689                                                  imap[i].br_blockcount))) {
 690                                 *map = imap[i];
 691                                 *retmap = 1;
 692                                 XFS_STATS_INC(xfsstats.xs_xstrat_quick);
 693                                 return 0;
 694                         }
 695                         count_fsb -= imap[i].br_blockcount;
 696                 }
 697
 698                 /* So far we have not mapped the requested part of the
 699                  * file, just surrounding data, try again.
 700                  */
 701                 nimaps--;
 702                 offset_fsb = imap[nimaps].br_startoff +
 703                              imap[nimaps].br_blockcount;
 704                 map_start_fsb = offset_fsb;
 705         }
 706
 707 trans_cancel:
 708         xfs_bmap_cancel(&free_list);
 709         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 710 error0:
 711         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 712         return XFS_ERROR(error);
 713 }
 714
 715 int
 716 xfs_iomap_write_unwritten(
 717         xfs_inode_t     *ip,
 718         loff_t          offset,
 719         size_t          count)
 720 {
 721         xfs_mount_t     *mp = ip->i_mount;
 722         xfs_trans_t     *tp;
 723         xfs_fileoff_t   offset_fsb;
 724         xfs_filblks_t   count_fsb;
 725         xfs_filblks_t   numblks_fsb;
 726         xfs_bmbt_irec_t imap;
 727         int             committed;
 728         int             error;
 729         int             nres;
 730         int             nimaps;
 731         xfs_fsblock_t   firstfsb;
 732         xfs_bmap_free_t free_list;
 733
 734         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 735         count_fsb = XFS_B_TO_FSB(mp, count);
 736
 737         do {
 738                 nres = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 739
 740                 /*
 741                  * set up a transaction to convert the range of extents
 742                  * from unwritten to real. Do allocations in a loop until
 743                  * we have covered the range passed in.
 744                  */
 745
 746                 tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 747                 error = xfs_trans_reserve(tp, nres,
 748                                 XFS_WRITE_LOG_RES(mp), 0,
 749                                 XFS_TRANS_PERM_LOG_RES,
 750                                 XFS_WRITE_LOG_COUNT);
 751                 if (error) {
 752                         xfs_trans_cancel(tp, 0);
 753                         goto error0;
 754                 }
 755
 756                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 757                 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 758                 xfs_trans_ihold(tp, ip);
 759
 760                 /*
 761                  * Modify the unwritten extent state of the buffer.
 762                  */
 763                 XFS_BMAP_INIT(&free_list, &firstfsb);
 764                 nimaps = 1;
 765                 error = xfs_bmapi(tp, ip, offset_fsb, count_fsb,
 766                                   XFS_BMAPI_WRITE, &firstfsb,
 767                                   1, &imap, &nimaps, &free_list);
 768                 if (error)
 769                         goto error_on_bmapi_transaction;
 770
 771                 error = xfs_bmap_finish(&(tp), &(free_list),
 772                                 firstfsb, &committed);
 773                 if (error)
 774                         goto error_on_bmapi_transaction;
 775
 776                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES, NULL);
 777                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 778                 if (error)
 779                         goto error0;
 780
 781                 if ((numblks_fsb = imap.br_blockcount) == 0) {
 782                         /*
 783                          * The numblks_fsb value should always get
 784                          * smaller, otherwise the loop is stuck.
 785                          */
 786                         ASSERT(imap.br_blockcount);
 787                         break;
 788                 }
 789                 offset_fsb += numblks_fsb;
 790                 count_fsb -= numblks_fsb;
 791         } while (count_fsb > 0);
 792
 793         return 0;
 794
 795 error_on_bmapi_transaction:
 796         xfs_bmap_cancel(&free_list);
 797         xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 798         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 799 error0:
 800         return XFS_ERROR(error);
 801 }