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