1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. 4 * Copyright (c) 2010 David Chinner. 5 * Copyright (c) 2011 Christoph Hellwig. 6 * All Rights Reserved. 7 */ 8 #include "xfs.h" 9 #include "xfs_fs.h" 10 #include "xfs_format.h" 11 #include "xfs_log_format.h" 12 #include "xfs_shared.h" 13 #include "xfs_trans_resv.h" 14 #include "xfs_sb.h" 15 #include "xfs_mount.h" 16 #include "xfs_alloc.h" 17 #include "xfs_extent_busy.h" 18 #include "xfs_trace.h" 19 #include "xfs_trans.h" 20 #include "xfs_log.h" 21 22 void 23 xfs_extent_busy_insert( 24 struct xfs_trans *tp, 25 xfs_agnumber_t agno, 26 xfs_agblock_t bno, 27 xfs_extlen_t len, 28 unsigned int flags) 29 { 30 struct xfs_extent_busy *new; 31 struct xfs_extent_busy *busyp; 32 struct xfs_perag *pag; 33 struct rb_node **rbp; 34 struct rb_node *parent = NULL; 35 36 new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_SLEEP); 37 new->agno = agno; 38 new->bno = bno; 39 new->length = len; 40 INIT_LIST_HEAD(&new->list); 41 new->flags = flags; 42 43 /* trace before insert to be able to see failed inserts */ 44 trace_xfs_extent_busy(tp->t_mountp, agno, bno, len); 45 46 pag = xfs_perag_get(tp->t_mountp, new->agno); 47 spin_lock(&pag->pagb_lock); 48 rbp = &pag->pagb_tree.rb_node; 49 while (*rbp) { 50 parent = *rbp; 51 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node); 52 53 if (new->bno < busyp->bno) { 54 rbp = &(*rbp)->rb_left; 55 ASSERT(new->bno + new->length <= busyp->bno); 56 } else if (new->bno > busyp->bno) { 57 rbp = &(*rbp)->rb_right; 58 ASSERT(bno >= busyp->bno + busyp->length); 59 } else { 60 ASSERT(0); 61 } 62 } 63 64 rb_link_node(&new->rb_node, parent, rbp); 65 rb_insert_color(&new->rb_node, &pag->pagb_tree); 66 67 list_add(&new->list, &tp->t_busy); 68 spin_unlock(&pag->pagb_lock); 69 xfs_perag_put(pag); 70 } 71 72 /* 73 * Search for a busy extent within the range of the extent we are about to 74 * allocate. You need to be holding the busy extent tree lock when calling 75 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy 76 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact 77 * match. This is done so that a non-zero return indicates an overlap that 78 * will require a synchronous transaction, but it can still be 79 * used to distinguish between a partial or exact match. 80 */ 81 int 82 xfs_extent_busy_search( 83 struct xfs_mount *mp, 84 xfs_agnumber_t agno, 85 xfs_agblock_t bno, 86 xfs_extlen_t len) 87 { 88 struct xfs_perag *pag; 89 struct rb_node *rbp; 90 struct xfs_extent_busy *busyp; 91 int match = 0; 92 93 pag = xfs_perag_get(mp, agno); 94 spin_lock(&pag->pagb_lock); 95 96 rbp = pag->pagb_tree.rb_node; 97 98 /* find closest start bno overlap */ 99 while (rbp) { 100 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node); 101 if (bno < busyp->bno) { 102 /* may overlap, but exact start block is lower */ 103 if (bno + len > busyp->bno) 104 match = -1; 105 rbp = rbp->rb_left; 106 } else if (bno > busyp->bno) { 107 /* may overlap, but exact start block is higher */ 108 if (bno < busyp->bno + busyp->length) 109 match = -1; 110 rbp = rbp->rb_right; 111 } else { 112 /* bno matches busyp, length determines exact match */ 113 match = (busyp->length == len) ? 1 : -1; 114 break; 115 } 116 } 117 spin_unlock(&pag->pagb_lock); 118 xfs_perag_put(pag); 119 return match; 120 } 121 122 /* 123 * The found free extent [fbno, fend] overlaps part or all of the given busy 124 * extent. If the overlap covers the beginning, the end, or all of the busy 125 * extent, the overlapping portion can be made unbusy and used for the 126 * allocation. We can't split a busy extent because we can't modify a 127 * transaction/CIL context busy list, but we can update an entry's block 128 * number or length. 129 * 130 * Returns true if the extent can safely be reused, or false if the search 131 * needs to be restarted. 132 */ 133 STATIC bool 134 xfs_extent_busy_update_extent( 135 struct xfs_mount *mp, 136 struct xfs_perag *pag, 137 struct xfs_extent_busy *busyp, 138 xfs_agblock_t fbno, 139 xfs_extlen_t flen, 140 bool userdata) __releases(&pag->pagb_lock) 141 __acquires(&pag->pagb_lock) 142 { 143 xfs_agblock_t fend = fbno + flen; 144 xfs_agblock_t bbno = busyp->bno; 145 xfs_agblock_t bend = bbno + busyp->length; 146 147 /* 148 * This extent is currently being discarded. Give the thread 149 * performing the discard a chance to mark the extent unbusy 150 * and retry. 151 */ 152 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) { 153 spin_unlock(&pag->pagb_lock); 154 delay(1); 155 spin_lock(&pag->pagb_lock); 156 return false; 157 } 158 159 /* 160 * If there is a busy extent overlapping a user allocation, we have 161 * no choice but to force the log and retry the search. 162 * 163 * Fortunately this does not happen during normal operation, but 164 * only if the filesystem is very low on space and has to dip into 165 * the AGFL for normal allocations. 166 */ 167 if (userdata) 168 goto out_force_log; 169 170 if (bbno < fbno && bend > fend) { 171 /* 172 * Case 1: 173 * bbno bend 174 * +BBBBBBBBBBBBBBBBB+ 175 * +---------+ 176 * fbno fend 177 */ 178 179 /* 180 * We would have to split the busy extent to be able to track 181 * it correct, which we cannot do because we would have to 182 * modify the list of busy extents attached to the transaction 183 * or CIL context, which is immutable. 184 * 185 * Force out the log to clear the busy extent and retry the 186 * search. 187 */ 188 goto out_force_log; 189 } else if (bbno >= fbno && bend <= fend) { 190 /* 191 * Case 2: 192 * bbno bend 193 * +BBBBBBBBBBBBBBBBB+ 194 * +-----------------+ 195 * fbno fend 196 * 197 * Case 3: 198 * bbno bend 199 * +BBBBBBBBBBBBBBBBB+ 200 * +--------------------------+ 201 * fbno fend 202 * 203 * Case 4: 204 * bbno bend 205 * +BBBBBBBBBBBBBBBBB+ 206 * +--------------------------+ 207 * fbno fend 208 * 209 * Case 5: 210 * bbno bend 211 * +BBBBBBBBBBBBBBBBB+ 212 * +-----------------------------------+ 213 * fbno fend 214 * 215 */ 216 217 /* 218 * The busy extent is fully covered by the extent we are 219 * allocating, and can simply be removed from the rbtree. 220 * However we cannot remove it from the immutable list 221 * tracking busy extents in the transaction or CIL context, 222 * so set the length to zero to mark it invalid. 223 * 224 * We also need to restart the busy extent search from the 225 * tree root, because erasing the node can rearrange the 226 * tree topology. 227 */ 228 rb_erase(&busyp->rb_node, &pag->pagb_tree); 229 busyp->length = 0; 230 return false; 231 } else if (fend < bend) { 232 /* 233 * Case 6: 234 * bbno bend 235 * +BBBBBBBBBBBBBBBBB+ 236 * +---------+ 237 * fbno fend 238 * 239 * Case 7: 240 * bbno bend 241 * +BBBBBBBBBBBBBBBBB+ 242 * +------------------+ 243 * fbno fend 244 * 245 */ 246 busyp->bno = fend; 247 } else if (bbno < fbno) { 248 /* 249 * Case 8: 250 * bbno bend 251 * +BBBBBBBBBBBBBBBBB+ 252 * +-------------+ 253 * fbno fend 254 * 255 * Case 9: 256 * bbno bend 257 * +BBBBBBBBBBBBBBBBB+ 258 * +----------------------+ 259 * fbno fend 260 */ 261 busyp->length = fbno - busyp->bno; 262 } else { 263 ASSERT(0); 264 } 265 266 trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen); 267 return true; 268 269 out_force_log: 270 spin_unlock(&pag->pagb_lock); 271 xfs_log_force(mp, XFS_LOG_SYNC); 272 trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen); 273 spin_lock(&pag->pagb_lock); 274 return false; 275 } 276 277 278 /* 279 * For a given extent [fbno, flen], make sure we can reuse it safely. 280 */ 281 void 282 xfs_extent_busy_reuse( 283 struct xfs_mount *mp, 284 xfs_agnumber_t agno, 285 xfs_agblock_t fbno, 286 xfs_extlen_t flen, 287 bool userdata) 288 { 289 struct xfs_perag *pag; 290 struct rb_node *rbp; 291 292 ASSERT(flen > 0); 293 294 pag = xfs_perag_get(mp, agno); 295 spin_lock(&pag->pagb_lock); 296 restart: 297 rbp = pag->pagb_tree.rb_node; 298 while (rbp) { 299 struct xfs_extent_busy *busyp = 300 rb_entry(rbp, struct xfs_extent_busy, rb_node); 301 xfs_agblock_t bbno = busyp->bno; 302 xfs_agblock_t bend = bbno + busyp->length; 303 304 if (fbno + flen <= bbno) { 305 rbp = rbp->rb_left; 306 continue; 307 } else if (fbno >= bend) { 308 rbp = rbp->rb_right; 309 continue; 310 } 311 312 if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen, 313 userdata)) 314 goto restart; 315 } 316 spin_unlock(&pag->pagb_lock); 317 xfs_perag_put(pag); 318 } 319 320 /* 321 * For a given extent [fbno, flen], search the busy extent list to find a 322 * subset of the extent that is not busy. If *rlen is smaller than 323 * args->minlen no suitable extent could be found, and the higher level 324 * code needs to force out the log and retry the allocation. 325 * 326 * Return the current busy generation for the AG if the extent is busy. This 327 * value can be used to wait for at least one of the currently busy extents 328 * to be cleared. Note that the busy list is not guaranteed to be empty after 329 * the gen is woken. The state of a specific extent must always be confirmed 330 * with another call to xfs_extent_busy_trim() before it can be used. 331 */ 332 bool 333 xfs_extent_busy_trim( 334 struct xfs_alloc_arg *args, 335 xfs_agblock_t *bno, 336 xfs_extlen_t *len, 337 unsigned *busy_gen) 338 { 339 xfs_agblock_t fbno; 340 xfs_extlen_t flen; 341 struct rb_node *rbp; 342 bool ret = false; 343 344 ASSERT(*len > 0); 345 346 spin_lock(&args->pag->pagb_lock); 347 restart: 348 fbno = *bno; 349 flen = *len; 350 rbp = args->pag->pagb_tree.rb_node; 351 while (rbp && flen >= args->minlen) { 352 struct xfs_extent_busy *busyp = 353 rb_entry(rbp, struct xfs_extent_busy, rb_node); 354 xfs_agblock_t fend = fbno + flen; 355 xfs_agblock_t bbno = busyp->bno; 356 xfs_agblock_t bend = bbno + busyp->length; 357 358 if (fend <= bbno) { 359 rbp = rbp->rb_left; 360 continue; 361 } else if (fbno >= bend) { 362 rbp = rbp->rb_right; 363 continue; 364 } 365 366 /* 367 * If this is a metadata allocation, try to reuse the busy 368 * extent instead of trimming the allocation. 369 */ 370 if (!xfs_alloc_is_userdata(args->datatype) && 371 !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) { 372 if (!xfs_extent_busy_update_extent(args->mp, args->pag, 373 busyp, fbno, flen, 374 false)) 375 goto restart; 376 continue; 377 } 378 379 if (bbno <= fbno) { 380 /* start overlap */ 381 382 /* 383 * Case 1: 384 * bbno bend 385 * +BBBBBBBBBBBBBBBBB+ 386 * +---------+ 387 * fbno fend 388 * 389 * Case 2: 390 * bbno bend 391 * +BBBBBBBBBBBBBBBBB+ 392 * +-------------+ 393 * fbno fend 394 * 395 * Case 3: 396 * bbno bend 397 * +BBBBBBBBBBBBBBBBB+ 398 * +-------------+ 399 * fbno fend 400 * 401 * Case 4: 402 * bbno bend 403 * +BBBBBBBBBBBBBBBBB+ 404 * +-----------------+ 405 * fbno fend 406 * 407 * No unbusy region in extent, return failure. 408 */ 409 if (fend <= bend) 410 goto fail; 411 412 /* 413 * Case 5: 414 * bbno bend 415 * +BBBBBBBBBBBBBBBBB+ 416 * +----------------------+ 417 * fbno fend 418 * 419 * Case 6: 420 * bbno bend 421 * +BBBBBBBBBBBBBBBBB+ 422 * +--------------------------+ 423 * fbno fend 424 * 425 * Needs to be trimmed to: 426 * +-------+ 427 * fbno fend 428 */ 429 fbno = bend; 430 } else if (bend >= fend) { 431 /* end overlap */ 432 433 /* 434 * Case 7: 435 * bbno bend 436 * +BBBBBBBBBBBBBBBBB+ 437 * +------------------+ 438 * fbno fend 439 * 440 * Case 8: 441 * bbno bend 442 * +BBBBBBBBBBBBBBBBB+ 443 * +--------------------------+ 444 * fbno fend 445 * 446 * Needs to be trimmed to: 447 * +-------+ 448 * fbno fend 449 */ 450 fend = bbno; 451 } else { 452 /* middle overlap */ 453 454 /* 455 * Case 9: 456 * bbno bend 457 * +BBBBBBBBBBBBBBBBB+ 458 * +-----------------------------------+ 459 * fbno fend 460 * 461 * Can be trimmed to: 462 * +-------+ OR +-------+ 463 * fbno fend fbno fend 464 * 465 * Backward allocation leads to significant 466 * fragmentation of directories, which degrades 467 * directory performance, therefore we always want to 468 * choose the option that produces forward allocation 469 * patterns. 470 * Preferring the lower bno extent will make the next 471 * request use "fend" as the start of the next 472 * allocation; if the segment is no longer busy at 473 * that point, we'll get a contiguous allocation, but 474 * even if it is still busy, we will get a forward 475 * allocation. 476 * We try to avoid choosing the segment at "bend", 477 * because that can lead to the next allocation 478 * taking the segment at "fbno", which would be a 479 * backward allocation. We only use the segment at 480 * "fbno" if it is much larger than the current 481 * requested size, because in that case there's a 482 * good chance subsequent allocations will be 483 * contiguous. 484 */ 485 if (bbno - fbno >= args->maxlen) { 486 /* left candidate fits perfect */ 487 fend = bbno; 488 } else if (fend - bend >= args->maxlen * 4) { 489 /* right candidate has enough free space */ 490 fbno = bend; 491 } else if (bbno - fbno >= args->minlen) { 492 /* left candidate fits minimum requirement */ 493 fend = bbno; 494 } else { 495 goto fail; 496 } 497 } 498 499 flen = fend - fbno; 500 } 501 out: 502 503 if (fbno != *bno || flen != *len) { 504 trace_xfs_extent_busy_trim(args->mp, args->agno, *bno, *len, 505 fbno, flen); 506 *bno = fbno; 507 *len = flen; 508 *busy_gen = args->pag->pagb_gen; 509 ret = true; 510 } 511 spin_unlock(&args->pag->pagb_lock); 512 return ret; 513 fail: 514 /* 515 * Return a zero extent length as failure indications. All callers 516 * re-check if the trimmed extent satisfies the minlen requirement. 517 */ 518 flen = 0; 519 goto out; 520 } 521 522 STATIC void 523 xfs_extent_busy_clear_one( 524 struct xfs_mount *mp, 525 struct xfs_perag *pag, 526 struct xfs_extent_busy *busyp) 527 { 528 if (busyp->length) { 529 trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno, 530 busyp->length); 531 rb_erase(&busyp->rb_node, &pag->pagb_tree); 532 } 533 534 list_del_init(&busyp->list); 535 kmem_free(busyp); 536 } 537 538 static void 539 xfs_extent_busy_put_pag( 540 struct xfs_perag *pag, 541 bool wakeup) 542 __releases(pag->pagb_lock) 543 { 544 if (wakeup) { 545 pag->pagb_gen++; 546 wake_up_all(&pag->pagb_wait); 547 } 548 549 spin_unlock(&pag->pagb_lock); 550 xfs_perag_put(pag); 551 } 552 553 /* 554 * Remove all extents on the passed in list from the busy extents tree. 555 * If do_discard is set skip extents that need to be discarded, and mark 556 * these as undergoing a discard operation instead. 557 */ 558 void 559 xfs_extent_busy_clear( 560 struct xfs_mount *mp, 561 struct list_head *list, 562 bool do_discard) 563 { 564 struct xfs_extent_busy *busyp, *n; 565 struct xfs_perag *pag = NULL; 566 xfs_agnumber_t agno = NULLAGNUMBER; 567 bool wakeup = false; 568 569 list_for_each_entry_safe(busyp, n, list, list) { 570 if (busyp->agno != agno) { 571 if (pag) 572 xfs_extent_busy_put_pag(pag, wakeup); 573 agno = busyp->agno; 574 pag = xfs_perag_get(mp, agno); 575 spin_lock(&pag->pagb_lock); 576 wakeup = false; 577 } 578 579 if (do_discard && busyp->length && 580 !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD)) { 581 busyp->flags = XFS_EXTENT_BUSY_DISCARDED; 582 } else { 583 xfs_extent_busy_clear_one(mp, pag, busyp); 584 wakeup = true; 585 } 586 } 587 588 if (pag) 589 xfs_extent_busy_put_pag(pag, wakeup); 590 } 591 592 /* 593 * Flush out all busy extents for this AG. 594 */ 595 void 596 xfs_extent_busy_flush( 597 struct xfs_mount *mp, 598 struct xfs_perag *pag, 599 unsigned busy_gen) 600 { 601 DEFINE_WAIT (wait); 602 int error; 603 604 error = xfs_log_force(mp, XFS_LOG_SYNC); 605 if (error) 606 return; 607 608 do { 609 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE); 610 if (busy_gen != READ_ONCE(pag->pagb_gen)) 611 break; 612 schedule(); 613 } while (1); 614 615 finish_wait(&pag->pagb_wait, &wait); 616 } 617 618 void 619 xfs_extent_busy_wait_all( 620 struct xfs_mount *mp) 621 { 622 DEFINE_WAIT (wait); 623 xfs_agnumber_t agno; 624 625 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) { 626 struct xfs_perag *pag = xfs_perag_get(mp, agno); 627 628 do { 629 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE); 630 if (RB_EMPTY_ROOT(&pag->pagb_tree)) 631 break; 632 schedule(); 633 } while (1); 634 finish_wait(&pag->pagb_wait, &wait); 635 636 xfs_perag_put(pag); 637 } 638 } 639 640 /* 641 * Callback for list_sort to sort busy extents by the AG they reside in. 642 */ 643 int 644 xfs_extent_busy_ag_cmp( 645 void *priv, 646 struct list_head *l1, 647 struct list_head *l2) 648 { 649 struct xfs_extent_busy *b1 = 650 container_of(l1, struct xfs_extent_busy, list); 651 struct xfs_extent_busy *b2 = 652 container_of(l2, struct xfs_extent_busy, list); 653 s32 diff; 654 655 diff = b1->agno - b2->agno; 656 if (!diff) 657 diff = b1->bno - b2->bno; 658 return diff; 659 } 660