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