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_shared.h" 21 #include "xfs_format.h" 22 #include "xfs_log_format.h" 23 #include "xfs_trans_resv.h" 24 #include "xfs_mount.h" 25 #include "xfs_inode.h" 26 #include "xfs_btree.h" 27 #include "xfs_bmap_btree.h" 28 #include "xfs_bmap.h" 29 #include "xfs_bmap_util.h" 30 #include "xfs_error.h" 31 #include "xfs_trans.h" 32 #include "xfs_trans_space.h" 33 #include "xfs_iomap.h" 34 #include "xfs_trace.h" 35 #include "xfs_icache.h" 36 #include "xfs_quota.h" 37 #include "xfs_dquot_item.h" 38 #include "xfs_dquot.h" 39 40 41 #define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \ 42 << mp->m_writeio_log) 43 #define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP 44 45 STATIC int 46 xfs_iomap_eof_align_last_fsb( 47 xfs_mount_t *mp, 48 xfs_inode_t *ip, 49 xfs_extlen_t extsize, 50 xfs_fileoff_t *last_fsb) 51 { 52 xfs_extlen_t align = 0; 53 int eof, error; 54 55 if (!XFS_IS_REALTIME_INODE(ip)) { 56 /* 57 * Round up the allocation request to a stripe unit 58 * (m_dalign) boundary if the file size is >= stripe unit 59 * size, and we are allocating past the allocation eof. 60 * 61 * If mounted with the "-o swalloc" option the alignment is 62 * increased from the strip unit size to the stripe width. 63 */ 64 if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC)) 65 align = mp->m_swidth; 66 else if (mp->m_dalign) 67 align = mp->m_dalign; 68 69 if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align)) 70 align = 0; 71 } 72 73 /* 74 * Always round up the allocation request to an extent boundary 75 * (when file on a real-time subvolume or has di_extsize hint). 76 */ 77 if (extsize) { 78 if (align) 79 align = roundup_64(align, extsize); 80 else 81 align = extsize; 82 } 83 84 if (align) { 85 xfs_fileoff_t new_last_fsb = roundup_64(*last_fsb, align); 86 error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof); 87 if (error) 88 return error; 89 if (eof) 90 *last_fsb = new_last_fsb; 91 } 92 return 0; 93 } 94 95 STATIC int 96 xfs_alert_fsblock_zero( 97 xfs_inode_t *ip, 98 xfs_bmbt_irec_t *imap) 99 { 100 xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO, 101 "Access to block zero in inode %llu " 102 "start_block: %llx start_off: %llx " 103 "blkcnt: %llx extent-state: %x", 104 (unsigned long long)ip->i_ino, 105 (unsigned long long)imap->br_startblock, 106 (unsigned long long)imap->br_startoff, 107 (unsigned long long)imap->br_blockcount, 108 imap->br_state); 109 return -EFSCORRUPTED; 110 } 111 112 int 113 xfs_iomap_write_direct( 114 xfs_inode_t *ip, 115 xfs_off_t offset, 116 size_t count, 117 xfs_bmbt_irec_t *imap, 118 int nmaps) 119 { 120 xfs_mount_t *mp = ip->i_mount; 121 xfs_fileoff_t offset_fsb; 122 xfs_fileoff_t last_fsb; 123 xfs_filblks_t count_fsb, resaligned; 124 xfs_fsblock_t firstfsb; 125 xfs_extlen_t extsz, temp; 126 int nimaps; 127 int quota_flag; 128 int rt; 129 xfs_trans_t *tp; 130 xfs_bmap_free_t free_list; 131 uint qblocks, resblks, resrtextents; 132 int committed; 133 int error; 134 135 error = xfs_qm_dqattach(ip, 0); 136 if (error) 137 return error; 138 139 rt = XFS_IS_REALTIME_INODE(ip); 140 extsz = xfs_get_extsz_hint(ip); 141 142 offset_fsb = XFS_B_TO_FSBT(mp, offset); 143 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count))); 144 if ((offset + count) > XFS_ISIZE(ip)) { 145 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb); 146 if (error) 147 return error; 148 } else { 149 if (nmaps && (imap->br_startblock == HOLESTARTBLOCK)) 150 last_fsb = MIN(last_fsb, (xfs_fileoff_t) 151 imap->br_blockcount + 152 imap->br_startoff); 153 } 154 count_fsb = last_fsb - offset_fsb; 155 ASSERT(count_fsb > 0); 156 157 resaligned = count_fsb; 158 if (unlikely(extsz)) { 159 if ((temp = do_mod(offset_fsb, extsz))) 160 resaligned += temp; 161 if ((temp = do_mod(resaligned, extsz))) 162 resaligned += extsz - temp; 163 } 164 165 if (unlikely(rt)) { 166 resrtextents = qblocks = resaligned; 167 resrtextents /= mp->m_sb.sb_rextsize; 168 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); 169 quota_flag = XFS_QMOPT_RES_RTBLKS; 170 } else { 171 resrtextents = 0; 172 resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned); 173 quota_flag = XFS_QMOPT_RES_REGBLKS; 174 } 175 176 /* 177 * Allocate and setup the transaction 178 */ 179 tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT); 180 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, 181 resblks, resrtextents); 182 /* 183 * Check for running out of space, note: need lock to return 184 */ 185 if (error) { 186 xfs_trans_cancel(tp, 0); 187 return error; 188 } 189 190 xfs_ilock(ip, XFS_ILOCK_EXCL); 191 192 error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag); 193 if (error) 194 goto out_trans_cancel; 195 196 xfs_trans_ijoin(tp, ip, 0); 197 198 /* 199 * From this point onwards we overwrite the imap pointer that the 200 * caller gave to us. 201 */ 202 xfs_bmap_init(&free_list, &firstfsb); 203 nimaps = 1; 204 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, 205 XFS_BMAPI_PREALLOC, &firstfsb, 0, 206 imap, &nimaps, &free_list); 207 if (error) 208 goto out_bmap_cancel; 209 210 /* 211 * Complete the transaction 212 */ 213 error = xfs_bmap_finish(&tp, &free_list, &committed); 214 if (error) 215 goto out_bmap_cancel; 216 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); 217 if (error) 218 goto out_unlock; 219 220 /* 221 * Copy any maps to caller's array and return any error. 222 */ 223 if (nimaps == 0) { 224 error = -ENOSPC; 225 goto out_unlock; 226 } 227 228 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) 229 error = xfs_alert_fsblock_zero(ip, imap); 230 231 out_unlock: 232 xfs_iunlock(ip, XFS_ILOCK_EXCL); 233 return error; 234 235 out_bmap_cancel: 236 xfs_bmap_cancel(&free_list); 237 xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag); 238 out_trans_cancel: 239 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT); 240 goto out_unlock; 241 } 242 243 /* 244 * If the caller is doing a write at the end of the file, then extend the 245 * allocation out to the file system's write iosize. We clean up any extra 246 * space left over when the file is closed in xfs_inactive(). 247 * 248 * If we find we already have delalloc preallocation beyond EOF, don't do more 249 * preallocation as it it not needed. 250 */ 251 STATIC int 252 xfs_iomap_eof_want_preallocate( 253 xfs_mount_t *mp, 254 xfs_inode_t *ip, 255 xfs_off_t offset, 256 size_t count, 257 xfs_bmbt_irec_t *imap, 258 int nimaps, 259 int *prealloc) 260 { 261 xfs_fileoff_t start_fsb; 262 xfs_filblks_t count_fsb; 263 int n, error, imaps; 264 int found_delalloc = 0; 265 266 *prealloc = 0; 267 if (offset + count <= XFS_ISIZE(ip)) 268 return 0; 269 270 /* 271 * If the file is smaller than the minimum prealloc and we are using 272 * dynamic preallocation, don't do any preallocation at all as it is 273 * likely this is the only write to the file that is going to be done. 274 */ 275 if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) && 276 XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks)) 277 return 0; 278 279 /* 280 * If there are any real blocks past eof, then don't 281 * do any speculative allocation. 282 */ 283 start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1))); 284 count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes); 285 while (count_fsb > 0) { 286 imaps = nimaps; 287 error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps, 288 0); 289 if (error) 290 return error; 291 for (n = 0; n < imaps; n++) { 292 if ((imap[n].br_startblock != HOLESTARTBLOCK) && 293 (imap[n].br_startblock != DELAYSTARTBLOCK)) 294 return 0; 295 start_fsb += imap[n].br_blockcount; 296 count_fsb -= imap[n].br_blockcount; 297 298 if (imap[n].br_startblock == DELAYSTARTBLOCK) 299 found_delalloc = 1; 300 } 301 } 302 if (!found_delalloc) 303 *prealloc = 1; 304 return 0; 305 } 306 307 /* 308 * Determine the initial size of the preallocation. We are beyond the current 309 * EOF here, but we need to take into account whether this is a sparse write or 310 * an extending write when determining the preallocation size. Hence we need to 311 * look up the extent that ends at the current write offset and use the result 312 * to determine the preallocation size. 313 * 314 * If the extent is a hole, then preallocation is essentially disabled. 315 * Otherwise we take the size of the preceeding data extent as the basis for the 316 * preallocation size. If the size of the extent is greater than half the 317 * maximum extent length, then use the current offset as the basis. This ensures 318 * that for large files the preallocation size always extends to MAXEXTLEN 319 * rather than falling short due to things like stripe unit/width alignment of 320 * real extents. 321 */ 322 STATIC xfs_fsblock_t 323 xfs_iomap_eof_prealloc_initial_size( 324 struct xfs_mount *mp, 325 struct xfs_inode *ip, 326 xfs_off_t offset, 327 xfs_bmbt_irec_t *imap, 328 int nimaps) 329 { 330 xfs_fileoff_t start_fsb; 331 int imaps = 1; 332 int error; 333 334 ASSERT(nimaps >= imaps); 335 336 /* if we are using a specific prealloc size, return now */ 337 if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) 338 return 0; 339 340 /* If the file is small, then use the minimum prealloc */ 341 if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign)) 342 return 0; 343 344 /* 345 * As we write multiple pages, the offset will always align to the 346 * start of a page and hence point to a hole at EOF. i.e. if the size is 347 * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096) 348 * will return FSB 1. Hence if there are blocks in the file, we want to 349 * point to the block prior to the EOF block and not the hole that maps 350 * directly at @offset. 351 */ 352 start_fsb = XFS_B_TO_FSB(mp, offset); 353 if (start_fsb) 354 start_fsb--; 355 error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE); 356 if (error) 357 return 0; 358 359 ASSERT(imaps == 1); 360 if (imap[0].br_startblock == HOLESTARTBLOCK) 361 return 0; 362 if (imap[0].br_blockcount <= (MAXEXTLEN >> 1)) 363 return imap[0].br_blockcount << 1; 364 return XFS_B_TO_FSB(mp, offset); 365 } 366 367 STATIC bool 368 xfs_quota_need_throttle( 369 struct xfs_inode *ip, 370 int type, 371 xfs_fsblock_t alloc_blocks) 372 { 373 struct xfs_dquot *dq = xfs_inode_dquot(ip, type); 374 375 if (!dq || !xfs_this_quota_on(ip->i_mount, type)) 376 return false; 377 378 /* no hi watermark, no throttle */ 379 if (!dq->q_prealloc_hi_wmark) 380 return false; 381 382 /* under the lo watermark, no throttle */ 383 if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark) 384 return false; 385 386 return true; 387 } 388 389 STATIC void 390 xfs_quota_calc_throttle( 391 struct xfs_inode *ip, 392 int type, 393 xfs_fsblock_t *qblocks, 394 int *qshift, 395 int64_t *qfreesp) 396 { 397 int64_t freesp; 398 int shift = 0; 399 struct xfs_dquot *dq = xfs_inode_dquot(ip, type); 400 401 /* no dq, or over hi wmark, squash the prealloc completely */ 402 if (!dq || dq->q_res_bcount >= dq->q_prealloc_hi_wmark) { 403 *qblocks = 0; 404 *qfreesp = 0; 405 return; 406 } 407 408 freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount; 409 if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) { 410 shift = 2; 411 if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT]) 412 shift += 2; 413 if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT]) 414 shift += 2; 415 } 416 417 if (freesp < *qfreesp) 418 *qfreesp = freesp; 419 420 /* only overwrite the throttle values if we are more aggressive */ 421 if ((freesp >> shift) < (*qblocks >> *qshift)) { 422 *qblocks = freesp; 423 *qshift = shift; 424 } 425 } 426 427 /* 428 * If we don't have a user specified preallocation size, dynamically increase 429 * the preallocation size as the size of the file grows. Cap the maximum size 430 * at a single extent or less if the filesystem is near full. The closer the 431 * filesystem is to full, the smaller the maximum prealocation. 432 */ 433 STATIC xfs_fsblock_t 434 xfs_iomap_prealloc_size( 435 struct xfs_mount *mp, 436 struct xfs_inode *ip, 437 xfs_off_t offset, 438 struct xfs_bmbt_irec *imap, 439 int nimaps) 440 { 441 xfs_fsblock_t alloc_blocks = 0; 442 int shift = 0; 443 int64_t freesp; 444 xfs_fsblock_t qblocks; 445 int qshift = 0; 446 447 alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset, 448 imap, nimaps); 449 if (!alloc_blocks) 450 goto check_writeio; 451 qblocks = alloc_blocks; 452 453 /* 454 * MAXEXTLEN is not a power of two value but we round the prealloc down 455 * to the nearest power of two value after throttling. To prevent the 456 * round down from unconditionally reducing the maximum supported prealloc 457 * size, we round up first, apply appropriate throttling, round down and 458 * cap the value to MAXEXTLEN. 459 */ 460 alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), 461 alloc_blocks); 462 463 freesp = percpu_counter_read_positive(&mp->m_fdblocks); 464 if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) { 465 shift = 2; 466 if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT]) 467 shift++; 468 if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT]) 469 shift++; 470 if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT]) 471 shift++; 472 if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT]) 473 shift++; 474 } 475 476 /* 477 * Check each quota to cap the prealloc size, provide a shift value to 478 * throttle with and adjust amount of available space. 479 */ 480 if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks)) 481 xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift, 482 &freesp); 483 if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks)) 484 xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift, 485 &freesp); 486 if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks)) 487 xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift, 488 &freesp); 489 490 /* 491 * The final prealloc size is set to the minimum of free space available 492 * in each of the quotas and the overall filesystem. 493 * 494 * The shift throttle value is set to the maximum value as determined by 495 * the global low free space values and per-quota low free space values. 496 */ 497 alloc_blocks = MIN(alloc_blocks, qblocks); 498 shift = MAX(shift, qshift); 499 500 if (shift) 501 alloc_blocks >>= shift; 502 /* 503 * rounddown_pow_of_two() returns an undefined result if we pass in 504 * alloc_blocks = 0. 505 */ 506 if (alloc_blocks) 507 alloc_blocks = rounddown_pow_of_two(alloc_blocks); 508 if (alloc_blocks > MAXEXTLEN) 509 alloc_blocks = MAXEXTLEN; 510 511 /* 512 * If we are still trying to allocate more space than is 513 * available, squash the prealloc hard. This can happen if we 514 * have a large file on a small filesystem and the above 515 * lowspace thresholds are smaller than MAXEXTLEN. 516 */ 517 while (alloc_blocks && alloc_blocks >= freesp) 518 alloc_blocks >>= 4; 519 520 check_writeio: 521 if (alloc_blocks < mp->m_writeio_blocks) 522 alloc_blocks = mp->m_writeio_blocks; 523 524 trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift, 525 mp->m_writeio_blocks); 526 527 return alloc_blocks; 528 } 529 530 int 531 xfs_iomap_write_delay( 532 xfs_inode_t *ip, 533 xfs_off_t offset, 534 size_t count, 535 xfs_bmbt_irec_t *ret_imap) 536 { 537 xfs_mount_t *mp = ip->i_mount; 538 xfs_fileoff_t offset_fsb; 539 xfs_fileoff_t last_fsb; 540 xfs_off_t aligned_offset; 541 xfs_fileoff_t ioalign; 542 xfs_extlen_t extsz; 543 int nimaps; 544 xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS]; 545 int prealloc; 546 int error; 547 548 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); 549 550 /* 551 * Make sure that the dquots are there. This doesn't hold 552 * the ilock across a disk read. 553 */ 554 error = xfs_qm_dqattach_locked(ip, 0); 555 if (error) 556 return error; 557 558 extsz = xfs_get_extsz_hint(ip); 559 offset_fsb = XFS_B_TO_FSBT(mp, offset); 560 561 error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count, 562 imap, XFS_WRITE_IMAPS, &prealloc); 563 if (error) 564 return error; 565 566 retry: 567 if (prealloc) { 568 xfs_fsblock_t alloc_blocks; 569 570 alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap, 571 XFS_WRITE_IMAPS); 572 573 aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1)); 574 ioalign = XFS_B_TO_FSBT(mp, aligned_offset); 575 last_fsb = ioalign + alloc_blocks; 576 } else { 577 last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count))); 578 } 579 580 if (prealloc || extsz) { 581 error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb); 582 if (error) 583 return error; 584 } 585 586 /* 587 * Make sure preallocation does not create extents beyond the range we 588 * actually support in this filesystem. 589 */ 590 if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes)) 591 last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes); 592 593 ASSERT(last_fsb > offset_fsb); 594 595 nimaps = XFS_WRITE_IMAPS; 596 error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb, 597 imap, &nimaps, XFS_BMAPI_ENTIRE); 598 switch (error) { 599 case 0: 600 case -ENOSPC: 601 case -EDQUOT: 602 break; 603 default: 604 return error; 605 } 606 607 /* 608 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry 609 * without EOF preallocation. 610 */ 611 if (nimaps == 0) { 612 trace_xfs_delalloc_enospc(ip, offset, count); 613 if (prealloc) { 614 prealloc = 0; 615 error = 0; 616 goto retry; 617 } 618 return error ? error : -ENOSPC; 619 } 620 621 if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip))) 622 return xfs_alert_fsblock_zero(ip, &imap[0]); 623 624 /* 625 * Tag the inode as speculatively preallocated so we can reclaim this 626 * space on demand, if necessary. 627 */ 628 if (prealloc) 629 xfs_inode_set_eofblocks_tag(ip); 630 631 *ret_imap = imap[0]; 632 return 0; 633 } 634 635 /* 636 * Pass in a delayed allocate extent, convert it to real extents; 637 * return to the caller the extent we create which maps on top of 638 * the originating callers request. 639 * 640 * Called without a lock on the inode. 641 * 642 * We no longer bother to look at the incoming map - all we have to 643 * guarantee is that whatever we allocate fills the required range. 644 */ 645 int 646 xfs_iomap_write_allocate( 647 xfs_inode_t *ip, 648 xfs_off_t offset, 649 xfs_bmbt_irec_t *imap) 650 { 651 xfs_mount_t *mp = ip->i_mount; 652 xfs_fileoff_t offset_fsb, last_block; 653 xfs_fileoff_t end_fsb, map_start_fsb; 654 xfs_fsblock_t first_block; 655 xfs_bmap_free_t free_list; 656 xfs_filblks_t count_fsb; 657 xfs_trans_t *tp; 658 int nimaps, committed; 659 int error = 0; 660 int nres; 661 662 /* 663 * Make sure that the dquots are there. 664 */ 665 error = xfs_qm_dqattach(ip, 0); 666 if (error) 667 return error; 668 669 offset_fsb = XFS_B_TO_FSBT(mp, offset); 670 count_fsb = imap->br_blockcount; 671 map_start_fsb = imap->br_startoff; 672 673 XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb)); 674 675 while (count_fsb != 0) { 676 /* 677 * Set up a transaction with which to allocate the 678 * backing store for the file. Do allocations in a 679 * loop until we get some space in the range we are 680 * interested in. The other space that might be allocated 681 * is in the delayed allocation extent on which we sit 682 * but before our buffer starts. 683 */ 684 685 nimaps = 0; 686 while (nimaps == 0) { 687 tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE); 688 tp->t_flags |= XFS_TRANS_RESERVE; 689 nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK); 690 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, 691 nres, 0); 692 if (error) { 693 xfs_trans_cancel(tp, 0); 694 return error; 695 } 696 xfs_ilock(ip, XFS_ILOCK_EXCL); 697 xfs_trans_ijoin(tp, ip, 0); 698 699 xfs_bmap_init(&free_list, &first_block); 700 701 /* 702 * it is possible that the extents have changed since 703 * we did the read call as we dropped the ilock for a 704 * while. We have to be careful about truncates or hole 705 * punchs here - we are not allowed to allocate 706 * non-delalloc blocks here. 707 * 708 * The only protection against truncation is the pages 709 * for the range we are being asked to convert are 710 * locked and hence a truncate will block on them 711 * first. 712 * 713 * As a result, if we go beyond the range we really 714 * need and hit an delalloc extent boundary followed by 715 * a hole while we have excess blocks in the map, we 716 * will fill the hole incorrectly and overrun the 717 * transaction reservation. 718 * 719 * Using a single map prevents this as we are forced to 720 * check each map we look for overlap with the desired 721 * range and abort as soon as we find it. Also, given 722 * that we only return a single map, having one beyond 723 * what we can return is probably a bit silly. 724 * 725 * We also need to check that we don't go beyond EOF; 726 * this is a truncate optimisation as a truncate sets 727 * the new file size before block on the pages we 728 * currently have locked under writeback. Because they 729 * are about to be tossed, we don't need to write them 730 * back.... 731 */ 732 nimaps = 1; 733 end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)); 734 error = xfs_bmap_last_offset(ip, &last_block, 735 XFS_DATA_FORK); 736 if (error) 737 goto trans_cancel; 738 739 last_block = XFS_FILEOFF_MAX(last_block, end_fsb); 740 if ((map_start_fsb + count_fsb) > last_block) { 741 count_fsb = last_block - map_start_fsb; 742 if (count_fsb == 0) { 743 error = -EAGAIN; 744 goto trans_cancel; 745 } 746 } 747 748 /* 749 * From this point onwards we overwrite the imap 750 * pointer that the caller gave to us. 751 */ 752 error = xfs_bmapi_write(tp, ip, map_start_fsb, 753 count_fsb, 0, 754 &first_block, 1, 755 imap, &nimaps, &free_list); 756 if (error) 757 goto trans_cancel; 758 759 error = xfs_bmap_finish(&tp, &free_list, &committed); 760 if (error) 761 goto trans_cancel; 762 763 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); 764 if (error) 765 goto error0; 766 767 xfs_iunlock(ip, XFS_ILOCK_EXCL); 768 } 769 770 /* 771 * See if we were able to allocate an extent that 772 * covers at least part of the callers request 773 */ 774 if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) 775 return xfs_alert_fsblock_zero(ip, imap); 776 777 if ((offset_fsb >= imap->br_startoff) && 778 (offset_fsb < (imap->br_startoff + 779 imap->br_blockcount))) { 780 XFS_STATS_INC(xs_xstrat_quick); 781 return 0; 782 } 783 784 /* 785 * So far we have not mapped the requested part of the 786 * file, just surrounding data, try again. 787 */ 788 count_fsb -= imap->br_blockcount; 789 map_start_fsb = imap->br_startoff + imap->br_blockcount; 790 } 791 792 trans_cancel: 793 xfs_bmap_cancel(&free_list); 794 xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT); 795 error0: 796 xfs_iunlock(ip, XFS_ILOCK_EXCL); 797 return error; 798 } 799 800 int 801 xfs_iomap_write_unwritten( 802 xfs_inode_t *ip, 803 xfs_off_t offset, 804 xfs_off_t count) 805 { 806 xfs_mount_t *mp = ip->i_mount; 807 xfs_fileoff_t offset_fsb; 808 xfs_filblks_t count_fsb; 809 xfs_filblks_t numblks_fsb; 810 xfs_fsblock_t firstfsb; 811 int nimaps; 812 xfs_trans_t *tp; 813 xfs_bmbt_irec_t imap; 814 xfs_bmap_free_t free_list; 815 xfs_fsize_t i_size; 816 uint resblks; 817 int committed; 818 int error; 819 820 trace_xfs_unwritten_convert(ip, offset, count); 821 822 offset_fsb = XFS_B_TO_FSBT(mp, offset); 823 count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count); 824 count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb); 825 826 /* 827 * Reserve enough blocks in this transaction for two complete extent 828 * btree splits. We may be converting the middle part of an unwritten 829 * extent and in this case we will insert two new extents in the btree 830 * each of which could cause a full split. 831 * 832 * This reservation amount will be used in the first call to 833 * xfs_bmbt_split() to select an AG with enough space to satisfy the 834 * rest of the operation. 835 */ 836 resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1; 837 838 do { 839 /* 840 * set up a transaction to convert the range of extents 841 * from unwritten to real. Do allocations in a loop until 842 * we have covered the range passed in. 843 * 844 * Note that we open code the transaction allocation here 845 * to pass KM_NOFS--we can't risk to recursing back into 846 * the filesystem here as we might be asked to write out 847 * the same inode that we complete here and might deadlock 848 * on the iolock. 849 */ 850 sb_start_intwrite(mp->m_super); 851 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS); 852 tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT; 853 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, 854 resblks, 0); 855 if (error) { 856 xfs_trans_cancel(tp, 0); 857 return error; 858 } 859 860 xfs_ilock(ip, XFS_ILOCK_EXCL); 861 xfs_trans_ijoin(tp, ip, 0); 862 863 /* 864 * Modify the unwritten extent state of the buffer. 865 */ 866 xfs_bmap_init(&free_list, &firstfsb); 867 nimaps = 1; 868 error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, 869 XFS_BMAPI_CONVERT, &firstfsb, 870 1, &imap, &nimaps, &free_list); 871 if (error) 872 goto error_on_bmapi_transaction; 873 874 /* 875 * Log the updated inode size as we go. We have to be careful 876 * to only log it up to the actual write offset if it is 877 * halfway into a block. 878 */ 879 i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb); 880 if (i_size > offset + count) 881 i_size = offset + count; 882 883 i_size = xfs_new_eof(ip, i_size); 884 if (i_size) { 885 ip->i_d.di_size = i_size; 886 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 887 } 888 889 error = xfs_bmap_finish(&tp, &free_list, &committed); 890 if (error) 891 goto error_on_bmapi_transaction; 892 893 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); 894 xfs_iunlock(ip, XFS_ILOCK_EXCL); 895 if (error) 896 return error; 897 898 if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) 899 return xfs_alert_fsblock_zero(ip, &imap); 900 901 if ((numblks_fsb = imap.br_blockcount) == 0) { 902 /* 903 * The numblks_fsb value should always get 904 * smaller, otherwise the loop is stuck. 905 */ 906 ASSERT(imap.br_blockcount); 907 break; 908 } 909 offset_fsb += numblks_fsb; 910 count_fsb -= numblks_fsb; 911 } while (count_fsb > 0); 912 913 return 0; 914 915 error_on_bmapi_transaction: 916 xfs_bmap_cancel(&free_list); 917 xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT)); 918 xfs_iunlock(ip, XFS_ILOCK_EXCL); 919 return error; 920 } 921