1 /* 2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. 3 * Copyright (c) 2010 David Chinner. 4 * Copyright (c) 2011 Christoph Hellwig. 5 * All Rights Reserved. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it would be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 #include "xfs.h" 21 #include "xfs_fs.h" 22 #include "xfs_format.h" 23 #include "xfs_log_format.h" 24 #include "xfs_shared.h" 25 #include "xfs_trans_resv.h" 26 #include "xfs_sb.h" 27 #include "xfs_mount.h" 28 #include "xfs_alloc.h" 29 #include "xfs_extent_busy.h" 30 #include "xfs_trace.h" 31 #include "xfs_trans.h" 32 #include "xfs_log.h" 33 34 void 35 xfs_extent_busy_insert( 36 struct xfs_trans *tp, 37 xfs_agnumber_t agno, 38 xfs_agblock_t bno, 39 xfs_extlen_t len, 40 unsigned int flags) 41 { 42 struct xfs_extent_busy *new; 43 struct xfs_extent_busy *busyp; 44 struct xfs_perag *pag; 45 struct rb_node **rbp; 46 struct rb_node *parent = NULL; 47 48 new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_MAYFAIL); 49 if (!new) { 50 /* 51 * No Memory! Since it is now not possible to track the free 52 * block, make this a synchronous transaction to insure that 53 * the block is not reused before this transaction commits. 54 */ 55 trace_xfs_extent_busy_enomem(tp->t_mountp, agno, bno, len); 56 xfs_trans_set_sync(tp); 57 return; 58 } 59 60 new->agno = agno; 61 new->bno = bno; 62 new->length = len; 63 INIT_LIST_HEAD(&new->list); 64 new->flags = flags; 65 66 /* trace before insert to be able to see failed inserts */ 67 trace_xfs_extent_busy(tp->t_mountp, agno, bno, len); 68 69 pag = xfs_perag_get(tp->t_mountp, new->agno); 70 spin_lock(&pag->pagb_lock); 71 rbp = &pag->pagb_tree.rb_node; 72 while (*rbp) { 73 parent = *rbp; 74 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node); 75 76 if (new->bno < busyp->bno) { 77 rbp = &(*rbp)->rb_left; 78 ASSERT(new->bno + new->length <= busyp->bno); 79 } else if (new->bno > busyp->bno) { 80 rbp = &(*rbp)->rb_right; 81 ASSERT(bno >= busyp->bno + busyp->length); 82 } else { 83 ASSERT(0); 84 } 85 } 86 87 rb_link_node(&new->rb_node, parent, rbp); 88 rb_insert_color(&new->rb_node, &pag->pagb_tree); 89 90 list_add(&new->list, &tp->t_busy); 91 spin_unlock(&pag->pagb_lock); 92 xfs_perag_put(pag); 93 } 94 95 /* 96 * Search for a busy extent within the range of the extent we are about to 97 * allocate. You need to be holding the busy extent tree lock when calling 98 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy 99 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact 100 * match. This is done so that a non-zero return indicates an overlap that 101 * will require a synchronous transaction, but it can still be 102 * used to distinguish between a partial or exact match. 103 */ 104 int 105 xfs_extent_busy_search( 106 struct xfs_mount *mp, 107 xfs_agnumber_t agno, 108 xfs_agblock_t bno, 109 xfs_extlen_t len) 110 { 111 struct xfs_perag *pag; 112 struct rb_node *rbp; 113 struct xfs_extent_busy *busyp; 114 int match = 0; 115 116 pag = xfs_perag_get(mp, agno); 117 spin_lock(&pag->pagb_lock); 118 119 rbp = pag->pagb_tree.rb_node; 120 121 /* find closest start bno overlap */ 122 while (rbp) { 123 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node); 124 if (bno < busyp->bno) { 125 /* may overlap, but exact start block is lower */ 126 if (bno + len > busyp->bno) 127 match = -1; 128 rbp = rbp->rb_left; 129 } else if (bno > busyp->bno) { 130 /* may overlap, but exact start block is higher */ 131 if (bno < busyp->bno + busyp->length) 132 match = -1; 133 rbp = rbp->rb_right; 134 } else { 135 /* bno matches busyp, length determines exact match */ 136 match = (busyp->length == len) ? 1 : -1; 137 break; 138 } 139 } 140 spin_unlock(&pag->pagb_lock); 141 xfs_perag_put(pag); 142 return match; 143 } 144 145 /* 146 * The found free extent [fbno, fend] overlaps part or all of the given busy 147 * extent. If the overlap covers the beginning, the end, or all of the busy 148 * extent, the overlapping portion can be made unbusy and used for the 149 * allocation. We can't split a busy extent because we can't modify a 150 * transaction/CIL context busy list, but we can update an entry's block 151 * number or length. 152 * 153 * Returns true if the extent can safely be reused, or false if the search 154 * needs to be restarted. 155 */ 156 STATIC bool 157 xfs_extent_busy_update_extent( 158 struct xfs_mount *mp, 159 struct xfs_perag *pag, 160 struct xfs_extent_busy *busyp, 161 xfs_agblock_t fbno, 162 xfs_extlen_t flen, 163 bool userdata) __releases(&pag->pagb_lock) 164 __acquires(&pag->pagb_lock) 165 { 166 xfs_agblock_t fend = fbno + flen; 167 xfs_agblock_t bbno = busyp->bno; 168 xfs_agblock_t bend = bbno + busyp->length; 169 170 /* 171 * This extent is currently being discarded. Give the thread 172 * performing the discard a chance to mark the extent unbusy 173 * and retry. 174 */ 175 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) { 176 spin_unlock(&pag->pagb_lock); 177 delay(1); 178 spin_lock(&pag->pagb_lock); 179 return false; 180 } 181 182 /* 183 * If there is a busy extent overlapping a user allocation, we have 184 * no choice but to force the log and retry the search. 185 * 186 * Fortunately this does not happen during normal operation, but 187 * only if the filesystem is very low on space and has to dip into 188 * the AGFL for normal allocations. 189 */ 190 if (userdata) 191 goto out_force_log; 192 193 if (bbno < fbno && bend > fend) { 194 /* 195 * Case 1: 196 * bbno bend 197 * +BBBBBBBBBBBBBBBBB+ 198 * +---------+ 199 * fbno fend 200 */ 201 202 /* 203 * We would have to split the busy extent to be able to track 204 * it correct, which we cannot do because we would have to 205 * modify the list of busy extents attached to the transaction 206 * or CIL context, which is immutable. 207 * 208 * Force out the log to clear the busy extent and retry the 209 * search. 210 */ 211 goto out_force_log; 212 } else if (bbno >= fbno && bend <= fend) { 213 /* 214 * Case 2: 215 * bbno bend 216 * +BBBBBBBBBBBBBBBBB+ 217 * +-----------------+ 218 * fbno fend 219 * 220 * Case 3: 221 * bbno bend 222 * +BBBBBBBBBBBBBBBBB+ 223 * +--------------------------+ 224 * fbno fend 225 * 226 * Case 4: 227 * bbno bend 228 * +BBBBBBBBBBBBBBBBB+ 229 * +--------------------------+ 230 * fbno fend 231 * 232 * Case 5: 233 * bbno bend 234 * +BBBBBBBBBBBBBBBBB+ 235 * +-----------------------------------+ 236 * fbno fend 237 * 238 */ 239 240 /* 241 * The busy extent is fully covered by the extent we are 242 * allocating, and can simply be removed from the rbtree. 243 * However we cannot remove it from the immutable list 244 * tracking busy extents in the transaction or CIL context, 245 * so set the length to zero to mark it invalid. 246 * 247 * We also need to restart the busy extent search from the 248 * tree root, because erasing the node can rearrange the 249 * tree topology. 250 */ 251 rb_erase(&busyp->rb_node, &pag->pagb_tree); 252 busyp->length = 0; 253 return false; 254 } else if (fend < bend) { 255 /* 256 * Case 6: 257 * bbno bend 258 * +BBBBBBBBBBBBBBBBB+ 259 * +---------+ 260 * fbno fend 261 * 262 * Case 7: 263 * bbno bend 264 * +BBBBBBBBBBBBBBBBB+ 265 * +------------------+ 266 * fbno fend 267 * 268 */ 269 busyp->bno = fend; 270 } else if (bbno < fbno) { 271 /* 272 * Case 8: 273 * bbno bend 274 * +BBBBBBBBBBBBBBBBB+ 275 * +-------------+ 276 * fbno fend 277 * 278 * Case 9: 279 * bbno bend 280 * +BBBBBBBBBBBBBBBBB+ 281 * +----------------------+ 282 * fbno fend 283 */ 284 busyp->length = fbno - busyp->bno; 285 } else { 286 ASSERT(0); 287 } 288 289 trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen); 290 return true; 291 292 out_force_log: 293 spin_unlock(&pag->pagb_lock); 294 xfs_log_force(mp, XFS_LOG_SYNC); 295 trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen); 296 spin_lock(&pag->pagb_lock); 297 return false; 298 } 299 300 301 /* 302 * For a given extent [fbno, flen], make sure we can reuse it safely. 303 */ 304 void 305 xfs_extent_busy_reuse( 306 struct xfs_mount *mp, 307 xfs_agnumber_t agno, 308 xfs_agblock_t fbno, 309 xfs_extlen_t flen, 310 bool userdata) 311 { 312 struct xfs_perag *pag; 313 struct rb_node *rbp; 314 315 ASSERT(flen > 0); 316 317 pag = xfs_perag_get(mp, agno); 318 spin_lock(&pag->pagb_lock); 319 restart: 320 rbp = pag->pagb_tree.rb_node; 321 while (rbp) { 322 struct xfs_extent_busy *busyp = 323 rb_entry(rbp, struct xfs_extent_busy, rb_node); 324 xfs_agblock_t bbno = busyp->bno; 325 xfs_agblock_t bend = bbno + busyp->length; 326 327 if (fbno + flen <= bbno) { 328 rbp = rbp->rb_left; 329 continue; 330 } else if (fbno >= bend) { 331 rbp = rbp->rb_right; 332 continue; 333 } 334 335 if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen, 336 userdata)) 337 goto restart; 338 } 339 spin_unlock(&pag->pagb_lock); 340 xfs_perag_put(pag); 341 } 342 343 /* 344 * For a given extent [fbno, flen], search the busy extent list to find a 345 * subset of the extent that is not busy. If *rlen is smaller than 346 * args->minlen no suitable extent could be found, and the higher level 347 * code needs to force out the log and retry the allocation. 348 */ 349 void 350 xfs_extent_busy_trim( 351 struct xfs_alloc_arg *args, 352 xfs_agblock_t bno, 353 xfs_extlen_t len, 354 xfs_agblock_t *rbno, 355 xfs_extlen_t *rlen) 356 { 357 xfs_agblock_t fbno; 358 xfs_extlen_t flen; 359 struct rb_node *rbp; 360 361 ASSERT(len > 0); 362 363 spin_lock(&args->pag->pagb_lock); 364 restart: 365 fbno = bno; 366 flen = len; 367 rbp = args->pag->pagb_tree.rb_node; 368 while (rbp && flen >= args->minlen) { 369 struct xfs_extent_busy *busyp = 370 rb_entry(rbp, struct xfs_extent_busy, rb_node); 371 xfs_agblock_t fend = fbno + flen; 372 xfs_agblock_t bbno = busyp->bno; 373 xfs_agblock_t bend = bbno + busyp->length; 374 375 if (fend <= bbno) { 376 rbp = rbp->rb_left; 377 continue; 378 } else if (fbno >= bend) { 379 rbp = rbp->rb_right; 380 continue; 381 } 382 383 /* 384 * If this is a metadata allocation, try to reuse the busy 385 * extent instead of trimming the allocation. 386 */ 387 if (!args->userdata && 388 !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) { 389 if (!xfs_extent_busy_update_extent(args->mp, args->pag, 390 busyp, fbno, flen, 391 false)) 392 goto restart; 393 continue; 394 } 395 396 if (bbno <= fbno) { 397 /* start overlap */ 398 399 /* 400 * Case 1: 401 * bbno bend 402 * +BBBBBBBBBBBBBBBBB+ 403 * +---------+ 404 * fbno fend 405 * 406 * Case 2: 407 * bbno bend 408 * +BBBBBBBBBBBBBBBBB+ 409 * +-------------+ 410 * fbno fend 411 * 412 * Case 3: 413 * bbno bend 414 * +BBBBBBBBBBBBBBBBB+ 415 * +-------------+ 416 * fbno fend 417 * 418 * Case 4: 419 * bbno bend 420 * +BBBBBBBBBBBBBBBBB+ 421 * +-----------------+ 422 * fbno fend 423 * 424 * No unbusy region in extent, return failure. 425 */ 426 if (fend <= bend) 427 goto fail; 428 429 /* 430 * Case 5: 431 * bbno bend 432 * +BBBBBBBBBBBBBBBBB+ 433 * +----------------------+ 434 * fbno fend 435 * 436 * Case 6: 437 * bbno bend 438 * +BBBBBBBBBBBBBBBBB+ 439 * +--------------------------+ 440 * fbno fend 441 * 442 * Needs to be trimmed to: 443 * +-------+ 444 * fbno fend 445 */ 446 fbno = bend; 447 } else if (bend >= fend) { 448 /* end overlap */ 449 450 /* 451 * Case 7: 452 * bbno bend 453 * +BBBBBBBBBBBBBBBBB+ 454 * +------------------+ 455 * fbno fend 456 * 457 * Case 8: 458 * bbno bend 459 * +BBBBBBBBBBBBBBBBB+ 460 * +--------------------------+ 461 * fbno fend 462 * 463 * Needs to be trimmed to: 464 * +-------+ 465 * fbno fend 466 */ 467 fend = bbno; 468 } else { 469 /* middle overlap */ 470 471 /* 472 * Case 9: 473 * bbno bend 474 * +BBBBBBBBBBBBBBBBB+ 475 * +-----------------------------------+ 476 * fbno fend 477 * 478 * Can be trimmed to: 479 * +-------+ OR +-------+ 480 * fbno fend fbno fend 481 * 482 * Backward allocation leads to significant 483 * fragmentation of directories, which degrades 484 * directory performance, therefore we always want to 485 * choose the option that produces forward allocation 486 * patterns. 487 * Preferring the lower bno extent will make the next 488 * request use "fend" as the start of the next 489 * allocation; if the segment is no longer busy at 490 * that point, we'll get a contiguous allocation, but 491 * even if it is still busy, we will get a forward 492 * allocation. 493 * We try to avoid choosing the segment at "bend", 494 * because that can lead to the next allocation 495 * taking the segment at "fbno", which would be a 496 * backward allocation. We only use the segment at 497 * "fbno" if it is much larger than the current 498 * requested size, because in that case there's a 499 * good chance subsequent allocations will be 500 * contiguous. 501 */ 502 if (bbno - fbno >= args->maxlen) { 503 /* left candidate fits perfect */ 504 fend = bbno; 505 } else if (fend - bend >= args->maxlen * 4) { 506 /* right candidate has enough free space */ 507 fbno = bend; 508 } else if (bbno - fbno >= args->minlen) { 509 /* left candidate fits minimum requirement */ 510 fend = bbno; 511 } else { 512 goto fail; 513 } 514 } 515 516 flen = fend - fbno; 517 } 518 spin_unlock(&args->pag->pagb_lock); 519 520 if (fbno != bno || flen != len) { 521 trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, 522 fbno, flen); 523 } 524 *rbno = fbno; 525 *rlen = flen; 526 return; 527 fail: 528 /* 529 * Return a zero extent length as failure indications. All callers 530 * re-check if the trimmed extent satisfies the minlen requirement. 531 */ 532 spin_unlock(&args->pag->pagb_lock); 533 trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, fbno, 0); 534 *rbno = fbno; 535 *rlen = 0; 536 } 537 538 STATIC void 539 xfs_extent_busy_clear_one( 540 struct xfs_mount *mp, 541 struct xfs_perag *pag, 542 struct xfs_extent_busy *busyp) 543 { 544 if (busyp->length) { 545 trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno, 546 busyp->length); 547 rb_erase(&busyp->rb_node, &pag->pagb_tree); 548 } 549 550 list_del_init(&busyp->list); 551 kmem_free(busyp); 552 } 553 554 /* 555 * Remove all extents on the passed in list from the busy extents tree. 556 * If do_discard is set skip extents that need to be discarded, and mark 557 * these as undergoing a discard operation instead. 558 */ 559 void 560 xfs_extent_busy_clear( 561 struct xfs_mount *mp, 562 struct list_head *list, 563 bool do_discard) 564 { 565 struct xfs_extent_busy *busyp, *n; 566 struct xfs_perag *pag = NULL; 567 xfs_agnumber_t agno = NULLAGNUMBER; 568 569 list_for_each_entry_safe(busyp, n, list, list) { 570 if (busyp->agno != agno) { 571 if (pag) { 572 spin_unlock(&pag->pagb_lock); 573 xfs_perag_put(pag); 574 } 575 pag = xfs_perag_get(mp, busyp->agno); 576 spin_lock(&pag->pagb_lock); 577 agno = busyp->agno; 578 } 579 580 if (do_discard && busyp->length && 581 !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD)) 582 busyp->flags = XFS_EXTENT_BUSY_DISCARDED; 583 else 584 xfs_extent_busy_clear_one(mp, pag, busyp); 585 } 586 587 if (pag) { 588 spin_unlock(&pag->pagb_lock); 589 xfs_perag_put(pag); 590 } 591 } 592 593 /* 594 * Callback for list_sort to sort busy extents by the AG they reside in. 595 */ 596 int 597 xfs_extent_busy_ag_cmp( 598 void *priv, 599 struct list_head *a, 600 struct list_head *b) 601 { 602 return container_of(a, struct xfs_extent_busy, list)->agno - 603 container_of(b, struct xfs_extent_busy, list)->agno; 604 } 605