1 // SPDX-License-Identifier: GPL-2.0 2 3 #include "misc.h" 4 #include "ctree.h" 5 #include "space-info.h" 6 #include "sysfs.h" 7 #include "volumes.h" 8 #include "free-space-cache.h" 9 #include "ordered-data.h" 10 #include "transaction.h" 11 #include "block-group.h" 12 13 /* 14 * HOW DOES SPACE RESERVATION WORK 15 * 16 * If you want to know about delalloc specifically, there is a separate comment 17 * for that with the delalloc code. This comment is about how the whole system 18 * works generally. 19 * 20 * BASIC CONCEPTS 21 * 22 * 1) space_info. This is the ultimate arbiter of how much space we can use. 23 * There's a description of the bytes_ fields with the struct declaration, 24 * refer to that for specifics on each field. Suffice it to say that for 25 * reservations we care about total_bytes - SUM(space_info->bytes_) when 26 * determining if there is space to make an allocation. There is a space_info 27 * for METADATA, SYSTEM, and DATA areas. 28 * 29 * 2) block_rsv's. These are basically buckets for every different type of 30 * metadata reservation we have. You can see the comment in the block_rsv 31 * code on the rules for each type, but generally block_rsv->reserved is how 32 * much space is accounted for in space_info->bytes_may_use. 33 * 34 * 3) btrfs_calc*_size. These are the worst case calculations we used based 35 * on the number of items we will want to modify. We have one for changing 36 * items, and one for inserting new items. Generally we use these helpers to 37 * determine the size of the block reserves, and then use the actual bytes 38 * values to adjust the space_info counters. 39 * 40 * MAKING RESERVATIONS, THE NORMAL CASE 41 * 42 * We call into either btrfs_reserve_data_bytes() or 43 * btrfs_reserve_metadata_bytes(), depending on which we're looking for, with 44 * num_bytes we want to reserve. 45 * 46 * ->reserve 47 * space_info->bytes_may_reserve += num_bytes 48 * 49 * ->extent allocation 50 * Call btrfs_add_reserved_bytes() which does 51 * space_info->bytes_may_reserve -= num_bytes 52 * space_info->bytes_reserved += extent_bytes 53 * 54 * ->insert reference 55 * Call btrfs_update_block_group() which does 56 * space_info->bytes_reserved -= extent_bytes 57 * space_info->bytes_used += extent_bytes 58 * 59 * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority) 60 * 61 * Assume we are unable to simply make the reservation because we do not have 62 * enough space 63 * 64 * -> __reserve_bytes 65 * create a reserve_ticket with ->bytes set to our reservation, add it to 66 * the tail of space_info->tickets, kick async flush thread 67 * 68 * ->handle_reserve_ticket 69 * wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set 70 * on the ticket. 71 * 72 * -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space 73 * Flushes various things attempting to free up space. 74 * 75 * -> btrfs_try_granting_tickets() 76 * This is called by anything that either subtracts space from 77 * space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the 78 * space_info->total_bytes. This loops through the ->priority_tickets and 79 * then the ->tickets list checking to see if the reservation can be 80 * completed. If it can the space is added to space_info->bytes_may_use and 81 * the ticket is woken up. 82 * 83 * -> ticket wakeup 84 * Check if ->bytes == 0, if it does we got our reservation and we can carry 85 * on, if not return the appropriate error (ENOSPC, but can be EINTR if we 86 * were interrupted.) 87 * 88 * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY 89 * 90 * Same as the above, except we add ourselves to the 91 * space_info->priority_tickets, and we do not use ticket->wait, we simply 92 * call flush_space() ourselves for the states that are safe for us to call 93 * without deadlocking and hope for the best. 94 * 95 * THE FLUSHING STATES 96 * 97 * Generally speaking we will have two cases for each state, a "nice" state 98 * and a "ALL THE THINGS" state. In btrfs we delay a lot of work in order to 99 * reduce the locking over head on the various trees, and even to keep from 100 * doing any work at all in the case of delayed refs. Each of these delayed 101 * things however hold reservations, and so letting them run allows us to 102 * reclaim space so we can make new reservations. 103 * 104 * FLUSH_DELAYED_ITEMS 105 * Every inode has a delayed item to update the inode. Take a simple write 106 * for example, we would update the inode item at write time to update the 107 * mtime, and then again at finish_ordered_io() time in order to update the 108 * isize or bytes. We keep these delayed items to coalesce these operations 109 * into a single operation done on demand. These are an easy way to reclaim 110 * metadata space. 111 * 112 * FLUSH_DELALLOC 113 * Look at the delalloc comment to get an idea of how much space is reserved 114 * for delayed allocation. We can reclaim some of this space simply by 115 * running delalloc, but usually we need to wait for ordered extents to 116 * reclaim the bulk of this space. 117 * 118 * FLUSH_DELAYED_REFS 119 * We have a block reserve for the outstanding delayed refs space, and every 120 * delayed ref operation holds a reservation. Running these is a quick way 121 * to reclaim space, but we want to hold this until the end because COW can 122 * churn a lot and we can avoid making some extent tree modifications if we 123 * are able to delay for as long as possible. 124 * 125 * ALLOC_CHUNK 126 * We will skip this the first time through space reservation, because of 127 * overcommit and we don't want to have a lot of useless metadata space when 128 * our worst case reservations will likely never come true. 129 * 130 * RUN_DELAYED_IPUTS 131 * If we're freeing inodes we're likely freeing checksums, file extent 132 * items, and extent tree items. Loads of space could be freed up by these 133 * operations, however they won't be usable until the transaction commits. 134 * 135 * COMMIT_TRANS 136 * This will commit the transaction. Historically we had a lot of logic 137 * surrounding whether or not we'd commit the transaction, but this waits born 138 * out of a pre-tickets era where we could end up committing the transaction 139 * thousands of times in a row without making progress. Now thanks to our 140 * ticketing system we know if we're not making progress and can error 141 * everybody out after a few commits rather than burning the disk hoping for 142 * a different answer. 143 * 144 * OVERCOMMIT 145 * 146 * Because we hold so many reservations for metadata we will allow you to 147 * reserve more space than is currently free in the currently allocate 148 * metadata space. This only happens with metadata, data does not allow 149 * overcommitting. 150 * 151 * You can see the current logic for when we allow overcommit in 152 * btrfs_can_overcommit(), but it only applies to unallocated space. If there 153 * is no unallocated space to be had, all reservations are kept within the 154 * free space in the allocated metadata chunks. 155 * 156 * Because of overcommitting, you generally want to use the 157 * btrfs_can_overcommit() logic for metadata allocations, as it does the right 158 * thing with or without extra unallocated space. 159 */ 160 161 u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info, 162 bool may_use_included) 163 { 164 ASSERT(s_info); 165 return s_info->bytes_used + s_info->bytes_reserved + 166 s_info->bytes_pinned + s_info->bytes_readonly + 167 s_info->bytes_zone_unusable + 168 (may_use_included ? s_info->bytes_may_use : 0); 169 } 170 171 /* 172 * after adding space to the filesystem, we need to clear the full flags 173 * on all the space infos. 174 */ 175 void btrfs_clear_space_info_full(struct btrfs_fs_info *info) 176 { 177 struct list_head *head = &info->space_info; 178 struct btrfs_space_info *found; 179 180 list_for_each_entry(found, head, list) 181 found->full = 0; 182 } 183 184 static int create_space_info(struct btrfs_fs_info *info, u64 flags) 185 { 186 187 struct btrfs_space_info *space_info; 188 int i; 189 int ret; 190 191 space_info = kzalloc(sizeof(*space_info), GFP_NOFS); 192 if (!space_info) 193 return -ENOMEM; 194 195 for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) 196 INIT_LIST_HEAD(&space_info->block_groups[i]); 197 init_rwsem(&space_info->groups_sem); 198 spin_lock_init(&space_info->lock); 199 space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK; 200 space_info->force_alloc = CHUNK_ALLOC_NO_FORCE; 201 INIT_LIST_HEAD(&space_info->ro_bgs); 202 INIT_LIST_HEAD(&space_info->tickets); 203 INIT_LIST_HEAD(&space_info->priority_tickets); 204 space_info->clamp = 1; 205 206 ret = btrfs_sysfs_add_space_info_type(info, space_info); 207 if (ret) 208 return ret; 209 210 list_add(&space_info->list, &info->space_info); 211 if (flags & BTRFS_BLOCK_GROUP_DATA) 212 info->data_sinfo = space_info; 213 214 return ret; 215 } 216 217 int btrfs_init_space_info(struct btrfs_fs_info *fs_info) 218 { 219 struct btrfs_super_block *disk_super; 220 u64 features; 221 u64 flags; 222 int mixed = 0; 223 int ret; 224 225 disk_super = fs_info->super_copy; 226 if (!btrfs_super_root(disk_super)) 227 return -EINVAL; 228 229 features = btrfs_super_incompat_flags(disk_super); 230 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS) 231 mixed = 1; 232 233 flags = BTRFS_BLOCK_GROUP_SYSTEM; 234 ret = create_space_info(fs_info, flags); 235 if (ret) 236 goto out; 237 238 if (mixed) { 239 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA; 240 ret = create_space_info(fs_info, flags); 241 } else { 242 flags = BTRFS_BLOCK_GROUP_METADATA; 243 ret = create_space_info(fs_info, flags); 244 if (ret) 245 goto out; 246 247 flags = BTRFS_BLOCK_GROUP_DATA; 248 ret = create_space_info(fs_info, flags); 249 } 250 out: 251 return ret; 252 } 253 254 void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags, 255 u64 total_bytes, u64 bytes_used, 256 u64 bytes_readonly, u64 bytes_zone_unusable, 257 struct btrfs_space_info **space_info) 258 { 259 struct btrfs_space_info *found; 260 int factor; 261 262 factor = btrfs_bg_type_to_factor(flags); 263 264 found = btrfs_find_space_info(info, flags); 265 ASSERT(found); 266 spin_lock(&found->lock); 267 found->total_bytes += total_bytes; 268 found->disk_total += total_bytes * factor; 269 found->bytes_used += bytes_used; 270 found->disk_used += bytes_used * factor; 271 found->bytes_readonly += bytes_readonly; 272 found->bytes_zone_unusable += bytes_zone_unusable; 273 if (total_bytes > 0) 274 found->full = 0; 275 btrfs_try_granting_tickets(info, found); 276 spin_unlock(&found->lock); 277 *space_info = found; 278 } 279 280 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info, 281 u64 flags) 282 { 283 struct list_head *head = &info->space_info; 284 struct btrfs_space_info *found; 285 286 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK; 287 288 list_for_each_entry(found, head, list) { 289 if (found->flags & flags) 290 return found; 291 } 292 return NULL; 293 } 294 295 static u64 calc_available_free_space(struct btrfs_fs_info *fs_info, 296 struct btrfs_space_info *space_info, 297 enum btrfs_reserve_flush_enum flush) 298 { 299 u64 profile; 300 u64 avail; 301 int factor; 302 303 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM) 304 profile = btrfs_system_alloc_profile(fs_info); 305 else 306 profile = btrfs_metadata_alloc_profile(fs_info); 307 308 avail = atomic64_read(&fs_info->free_chunk_space); 309 310 /* 311 * If we have dup, raid1 or raid10 then only half of the free 312 * space is actually usable. For raid56, the space info used 313 * doesn't include the parity drive, so we don't have to 314 * change the math 315 */ 316 factor = btrfs_bg_type_to_factor(profile); 317 avail = div_u64(avail, factor); 318 319 /* 320 * If we aren't flushing all things, let us overcommit up to 321 * 1/2th of the space. If we can flush, don't let us overcommit 322 * too much, let it overcommit up to 1/8 of the space. 323 */ 324 if (flush == BTRFS_RESERVE_FLUSH_ALL) 325 avail >>= 3; 326 else 327 avail >>= 1; 328 return avail; 329 } 330 331 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info, 332 struct btrfs_space_info *space_info, u64 bytes, 333 enum btrfs_reserve_flush_enum flush) 334 { 335 u64 avail; 336 u64 used; 337 338 /* Don't overcommit when in mixed mode */ 339 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA) 340 return 0; 341 342 used = btrfs_space_info_used(space_info, true); 343 avail = calc_available_free_space(fs_info, space_info, flush); 344 345 if (used + bytes < space_info->total_bytes + avail) 346 return 1; 347 return 0; 348 } 349 350 static void remove_ticket(struct btrfs_space_info *space_info, 351 struct reserve_ticket *ticket) 352 { 353 if (!list_empty(&ticket->list)) { 354 list_del_init(&ticket->list); 355 ASSERT(space_info->reclaim_size >= ticket->bytes); 356 space_info->reclaim_size -= ticket->bytes; 357 } 358 } 359 360 /* 361 * This is for space we already have accounted in space_info->bytes_may_use, so 362 * basically when we're returning space from block_rsv's. 363 */ 364 void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info, 365 struct btrfs_space_info *space_info) 366 { 367 struct list_head *head; 368 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH; 369 370 lockdep_assert_held(&space_info->lock); 371 372 head = &space_info->priority_tickets; 373 again: 374 while (!list_empty(head)) { 375 struct reserve_ticket *ticket; 376 u64 used = btrfs_space_info_used(space_info, true); 377 378 ticket = list_first_entry(head, struct reserve_ticket, list); 379 380 /* Check and see if our ticket can be satisfied now. */ 381 if ((used + ticket->bytes <= space_info->total_bytes) || 382 btrfs_can_overcommit(fs_info, space_info, ticket->bytes, 383 flush)) { 384 btrfs_space_info_update_bytes_may_use(fs_info, 385 space_info, 386 ticket->bytes); 387 remove_ticket(space_info, ticket); 388 ticket->bytes = 0; 389 space_info->tickets_id++; 390 wake_up(&ticket->wait); 391 } else { 392 break; 393 } 394 } 395 396 if (head == &space_info->priority_tickets) { 397 head = &space_info->tickets; 398 flush = BTRFS_RESERVE_FLUSH_ALL; 399 goto again; 400 } 401 } 402 403 #define DUMP_BLOCK_RSV(fs_info, rsv_name) \ 404 do { \ 405 struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \ 406 spin_lock(&__rsv->lock); \ 407 btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \ 408 __rsv->size, __rsv->reserved); \ 409 spin_unlock(&__rsv->lock); \ 410 } while (0) 411 412 static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info, 413 struct btrfs_space_info *info) 414 { 415 lockdep_assert_held(&info->lock); 416 417 btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull", 418 info->flags, 419 info->total_bytes - btrfs_space_info_used(info, true), 420 info->full ? "" : "not "); 421 btrfs_info(fs_info, 422 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu", 423 info->total_bytes, info->bytes_used, info->bytes_pinned, 424 info->bytes_reserved, info->bytes_may_use, 425 info->bytes_readonly, info->bytes_zone_unusable); 426 427 DUMP_BLOCK_RSV(fs_info, global_block_rsv); 428 DUMP_BLOCK_RSV(fs_info, trans_block_rsv); 429 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv); 430 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv); 431 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv); 432 433 } 434 435 void btrfs_dump_space_info(struct btrfs_fs_info *fs_info, 436 struct btrfs_space_info *info, u64 bytes, 437 int dump_block_groups) 438 { 439 struct btrfs_block_group *cache; 440 int index = 0; 441 442 spin_lock(&info->lock); 443 __btrfs_dump_space_info(fs_info, info); 444 spin_unlock(&info->lock); 445 446 if (!dump_block_groups) 447 return; 448 449 down_read(&info->groups_sem); 450 again: 451 list_for_each_entry(cache, &info->block_groups[index], list) { 452 spin_lock(&cache->lock); 453 btrfs_info(fs_info, 454 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu zone_unusable %s", 455 cache->start, cache->length, cache->used, cache->pinned, 456 cache->reserved, cache->zone_unusable, 457 cache->ro ? "[readonly]" : ""); 458 spin_unlock(&cache->lock); 459 btrfs_dump_free_space(cache, bytes); 460 } 461 if (++index < BTRFS_NR_RAID_TYPES) 462 goto again; 463 up_read(&info->groups_sem); 464 } 465 466 static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info, 467 u64 to_reclaim) 468 { 469 u64 bytes; 470 u64 nr; 471 472 bytes = btrfs_calc_insert_metadata_size(fs_info, 1); 473 nr = div64_u64(to_reclaim, bytes); 474 if (!nr) 475 nr = 1; 476 return nr; 477 } 478 479 #define EXTENT_SIZE_PER_ITEM SZ_256K 480 481 /* 482 * shrink metadata reservation for delalloc 483 */ 484 static void shrink_delalloc(struct btrfs_fs_info *fs_info, 485 struct btrfs_space_info *space_info, 486 u64 to_reclaim, bool wait_ordered, 487 bool for_preempt) 488 { 489 struct btrfs_trans_handle *trans; 490 u64 delalloc_bytes; 491 u64 ordered_bytes; 492 u64 items; 493 long time_left; 494 int loops; 495 496 /* Calc the number of the pages we need flush for space reservation */ 497 if (to_reclaim == U64_MAX) { 498 items = U64_MAX; 499 } else { 500 /* 501 * to_reclaim is set to however much metadata we need to 502 * reclaim, but reclaiming that much data doesn't really track 503 * exactly, so increase the amount to reclaim by 2x in order to 504 * make sure we're flushing enough delalloc to hopefully reclaim 505 * some metadata reservations. 506 */ 507 items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2; 508 to_reclaim = items * EXTENT_SIZE_PER_ITEM; 509 } 510 511 trans = (struct btrfs_trans_handle *)current->journal_info; 512 513 delalloc_bytes = percpu_counter_sum_positive( 514 &fs_info->delalloc_bytes); 515 ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes); 516 if (delalloc_bytes == 0 && ordered_bytes == 0) 517 return; 518 519 /* 520 * If we are doing more ordered than delalloc we need to just wait on 521 * ordered extents, otherwise we'll waste time trying to flush delalloc 522 * that likely won't give us the space back we need. 523 */ 524 if (ordered_bytes > delalloc_bytes && !for_preempt) 525 wait_ordered = true; 526 527 loops = 0; 528 while ((delalloc_bytes || ordered_bytes) && loops < 3) { 529 u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT; 530 long nr_pages = min_t(u64, temp, LONG_MAX); 531 532 btrfs_start_delalloc_roots(fs_info, nr_pages, true); 533 534 loops++; 535 if (wait_ordered && !trans) { 536 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1); 537 } else { 538 time_left = schedule_timeout_killable(1); 539 if (time_left) 540 break; 541 } 542 543 /* 544 * If we are for preemption we just want a one-shot of delalloc 545 * flushing so we can stop flushing if we decide we don't need 546 * to anymore. 547 */ 548 if (for_preempt) 549 break; 550 551 spin_lock(&space_info->lock); 552 if (list_empty(&space_info->tickets) && 553 list_empty(&space_info->priority_tickets)) { 554 spin_unlock(&space_info->lock); 555 break; 556 } 557 spin_unlock(&space_info->lock); 558 559 delalloc_bytes = percpu_counter_sum_positive( 560 &fs_info->delalloc_bytes); 561 ordered_bytes = percpu_counter_sum_positive( 562 &fs_info->ordered_bytes); 563 } 564 } 565 566 /* 567 * Try to flush some data based on policy set by @state. This is only advisory 568 * and may fail for various reasons. The caller is supposed to examine the 569 * state of @space_info to detect the outcome. 570 */ 571 static void flush_space(struct btrfs_fs_info *fs_info, 572 struct btrfs_space_info *space_info, u64 num_bytes, 573 enum btrfs_flush_state state, bool for_preempt) 574 { 575 struct btrfs_root *root = fs_info->extent_root; 576 struct btrfs_trans_handle *trans; 577 int nr; 578 int ret = 0; 579 580 switch (state) { 581 case FLUSH_DELAYED_ITEMS_NR: 582 case FLUSH_DELAYED_ITEMS: 583 if (state == FLUSH_DELAYED_ITEMS_NR) 584 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2; 585 else 586 nr = -1; 587 588 trans = btrfs_join_transaction(root); 589 if (IS_ERR(trans)) { 590 ret = PTR_ERR(trans); 591 break; 592 } 593 ret = btrfs_run_delayed_items_nr(trans, nr); 594 btrfs_end_transaction(trans); 595 break; 596 case FLUSH_DELALLOC: 597 case FLUSH_DELALLOC_WAIT: 598 shrink_delalloc(fs_info, space_info, num_bytes, 599 state == FLUSH_DELALLOC_WAIT, for_preempt); 600 break; 601 case FLUSH_DELAYED_REFS_NR: 602 case FLUSH_DELAYED_REFS: 603 trans = btrfs_join_transaction(root); 604 if (IS_ERR(trans)) { 605 ret = PTR_ERR(trans); 606 break; 607 } 608 if (state == FLUSH_DELAYED_REFS_NR) 609 nr = calc_reclaim_items_nr(fs_info, num_bytes); 610 else 611 nr = 0; 612 btrfs_run_delayed_refs(trans, nr); 613 btrfs_end_transaction(trans); 614 break; 615 case ALLOC_CHUNK: 616 case ALLOC_CHUNK_FORCE: 617 trans = btrfs_join_transaction(root); 618 if (IS_ERR(trans)) { 619 ret = PTR_ERR(trans); 620 break; 621 } 622 ret = btrfs_chunk_alloc(trans, 623 btrfs_get_alloc_profile(fs_info, space_info->flags), 624 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE : 625 CHUNK_ALLOC_FORCE); 626 btrfs_end_transaction(trans); 627 if (ret > 0 || ret == -ENOSPC) 628 ret = 0; 629 break; 630 case RUN_DELAYED_IPUTS: 631 /* 632 * If we have pending delayed iputs then we could free up a 633 * bunch of pinned space, so make sure we run the iputs before 634 * we do our pinned bytes check below. 635 */ 636 btrfs_run_delayed_iputs(fs_info); 637 btrfs_wait_on_delayed_iputs(fs_info); 638 break; 639 case COMMIT_TRANS: 640 ASSERT(current->journal_info == NULL); 641 trans = btrfs_join_transaction(root); 642 if (IS_ERR(trans)) { 643 ret = PTR_ERR(trans); 644 break; 645 } 646 ret = btrfs_commit_transaction(trans); 647 break; 648 default: 649 ret = -ENOSPC; 650 break; 651 } 652 653 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state, 654 ret, for_preempt); 655 return; 656 } 657 658 static inline u64 659 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info, 660 struct btrfs_space_info *space_info) 661 { 662 u64 used; 663 u64 avail; 664 u64 to_reclaim = space_info->reclaim_size; 665 666 lockdep_assert_held(&space_info->lock); 667 668 avail = calc_available_free_space(fs_info, space_info, 669 BTRFS_RESERVE_FLUSH_ALL); 670 used = btrfs_space_info_used(space_info, true); 671 672 /* 673 * We may be flushing because suddenly we have less space than we had 674 * before, and now we're well over-committed based on our current free 675 * space. If that's the case add in our overage so we make sure to put 676 * appropriate pressure on the flushing state machine. 677 */ 678 if (space_info->total_bytes + avail < used) 679 to_reclaim += used - (space_info->total_bytes + avail); 680 681 return to_reclaim; 682 } 683 684 static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info, 685 struct btrfs_space_info *space_info) 686 { 687 u64 global_rsv_size = fs_info->global_block_rsv.reserved; 688 u64 ordered, delalloc; 689 u64 thresh = div_factor_fine(space_info->total_bytes, 98); 690 u64 used; 691 692 /* If we're just plain full then async reclaim just slows us down. */ 693 if ((space_info->bytes_used + space_info->bytes_reserved + 694 global_rsv_size) >= thresh) 695 return false; 696 697 /* 698 * We have tickets queued, bail so we don't compete with the async 699 * flushers. 700 */ 701 if (space_info->reclaim_size) 702 return false; 703 704 /* 705 * If we have over half of the free space occupied by reservations or 706 * pinned then we want to start flushing. 707 * 708 * We do not do the traditional thing here, which is to say 709 * 710 * if (used >= ((total_bytes + avail) / 2)) 711 * return 1; 712 * 713 * because this doesn't quite work how we want. If we had more than 50% 714 * of the space_info used by bytes_used and we had 0 available we'd just 715 * constantly run the background flusher. Instead we want it to kick in 716 * if our reclaimable space exceeds our clamped free space. 717 * 718 * Our clamping range is 2^1 -> 2^8. Practically speaking that means 719 * the following: 720 * 721 * Amount of RAM Minimum threshold Maximum threshold 722 * 723 * 256GiB 1GiB 128GiB 724 * 128GiB 512MiB 64GiB 725 * 64GiB 256MiB 32GiB 726 * 32GiB 128MiB 16GiB 727 * 16GiB 64MiB 8GiB 728 * 729 * These are the range our thresholds will fall in, corresponding to how 730 * much delalloc we need for the background flusher to kick in. 731 */ 732 733 thresh = calc_available_free_space(fs_info, space_info, 734 BTRFS_RESERVE_FLUSH_ALL); 735 used = space_info->bytes_used + space_info->bytes_reserved + 736 space_info->bytes_readonly + global_rsv_size; 737 if (used < space_info->total_bytes) 738 thresh += space_info->total_bytes - used; 739 thresh >>= space_info->clamp; 740 741 used = space_info->bytes_pinned; 742 743 /* 744 * If we have more ordered bytes than delalloc bytes then we're either 745 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting 746 * around. Preemptive flushing is only useful in that it can free up 747 * space before tickets need to wait for things to finish. In the case 748 * of ordered extents, preemptively waiting on ordered extents gets us 749 * nothing, if our reservations are tied up in ordered extents we'll 750 * simply have to slow down writers by forcing them to wait on ordered 751 * extents. 752 * 753 * In the case that ordered is larger than delalloc, only include the 754 * block reserves that we would actually be able to directly reclaim 755 * from. In this case if we're heavy on metadata operations this will 756 * clearly be heavy enough to warrant preemptive flushing. In the case 757 * of heavy DIO or ordered reservations, preemptive flushing will just 758 * waste time and cause us to slow down. 759 * 760 * We want to make sure we truly are maxed out on ordered however, so 761 * cut ordered in half, and if it's still higher than delalloc then we 762 * can keep flushing. This is to avoid the case where we start 763 * flushing, and now delalloc == ordered and we stop preemptively 764 * flushing when we could still have several gigs of delalloc to flush. 765 */ 766 ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1; 767 delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes); 768 if (ordered >= delalloc) 769 used += fs_info->delayed_refs_rsv.reserved + 770 fs_info->delayed_block_rsv.reserved; 771 else 772 used += space_info->bytes_may_use - global_rsv_size; 773 774 return (used >= thresh && !btrfs_fs_closing(fs_info) && 775 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state)); 776 } 777 778 static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info, 779 struct btrfs_space_info *space_info, 780 struct reserve_ticket *ticket) 781 { 782 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv; 783 u64 min_bytes; 784 785 if (global_rsv->space_info != space_info) 786 return false; 787 788 spin_lock(&global_rsv->lock); 789 min_bytes = div_factor(global_rsv->size, 1); 790 if (global_rsv->reserved < min_bytes + ticket->bytes) { 791 spin_unlock(&global_rsv->lock); 792 return false; 793 } 794 global_rsv->reserved -= ticket->bytes; 795 remove_ticket(space_info, ticket); 796 ticket->bytes = 0; 797 wake_up(&ticket->wait); 798 space_info->tickets_id++; 799 if (global_rsv->reserved < global_rsv->size) 800 global_rsv->full = 0; 801 spin_unlock(&global_rsv->lock); 802 803 return true; 804 } 805 806 /* 807 * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets 808 * @fs_info - fs_info for this fs 809 * @space_info - the space info we were flushing 810 * 811 * We call this when we've exhausted our flushing ability and haven't made 812 * progress in satisfying tickets. The reservation code handles tickets in 813 * order, so if there is a large ticket first and then smaller ones we could 814 * very well satisfy the smaller tickets. This will attempt to wake up any 815 * tickets in the list to catch this case. 816 * 817 * This function returns true if it was able to make progress by clearing out 818 * other tickets, or if it stumbles across a ticket that was smaller than the 819 * first ticket. 820 */ 821 static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info, 822 struct btrfs_space_info *space_info) 823 { 824 struct reserve_ticket *ticket; 825 u64 tickets_id = space_info->tickets_id; 826 827 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) { 828 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info"); 829 __btrfs_dump_space_info(fs_info, space_info); 830 } 831 832 while (!list_empty(&space_info->tickets) && 833 tickets_id == space_info->tickets_id) { 834 ticket = list_first_entry(&space_info->tickets, 835 struct reserve_ticket, list); 836 837 if (ticket->steal && 838 steal_from_global_rsv(fs_info, space_info, ticket)) 839 return true; 840 841 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 842 btrfs_info(fs_info, "failing ticket with %llu bytes", 843 ticket->bytes); 844 845 remove_ticket(space_info, ticket); 846 ticket->error = -ENOSPC; 847 wake_up(&ticket->wait); 848 849 /* 850 * We're just throwing tickets away, so more flushing may not 851 * trip over btrfs_try_granting_tickets, so we need to call it 852 * here to see if we can make progress with the next ticket in 853 * the list. 854 */ 855 btrfs_try_granting_tickets(fs_info, space_info); 856 } 857 return (tickets_id != space_info->tickets_id); 858 } 859 860 /* 861 * This is for normal flushers, we can wait all goddamned day if we want to. We 862 * will loop and continuously try to flush as long as we are making progress. 863 * We count progress as clearing off tickets each time we have to loop. 864 */ 865 static void btrfs_async_reclaim_metadata_space(struct work_struct *work) 866 { 867 struct btrfs_fs_info *fs_info; 868 struct btrfs_space_info *space_info; 869 u64 to_reclaim; 870 enum btrfs_flush_state flush_state; 871 int commit_cycles = 0; 872 u64 last_tickets_id; 873 874 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work); 875 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); 876 877 spin_lock(&space_info->lock); 878 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); 879 if (!to_reclaim) { 880 space_info->flush = 0; 881 spin_unlock(&space_info->lock); 882 return; 883 } 884 last_tickets_id = space_info->tickets_id; 885 spin_unlock(&space_info->lock); 886 887 flush_state = FLUSH_DELAYED_ITEMS_NR; 888 do { 889 flush_space(fs_info, space_info, to_reclaim, flush_state, false); 890 spin_lock(&space_info->lock); 891 if (list_empty(&space_info->tickets)) { 892 space_info->flush = 0; 893 spin_unlock(&space_info->lock); 894 return; 895 } 896 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, 897 space_info); 898 if (last_tickets_id == space_info->tickets_id) { 899 flush_state++; 900 } else { 901 last_tickets_id = space_info->tickets_id; 902 flush_state = FLUSH_DELAYED_ITEMS_NR; 903 if (commit_cycles) 904 commit_cycles--; 905 } 906 907 /* 908 * We don't want to force a chunk allocation until we've tried 909 * pretty hard to reclaim space. Think of the case where we 910 * freed up a bunch of space and so have a lot of pinned space 911 * to reclaim. We would rather use that than possibly create a 912 * underutilized metadata chunk. So if this is our first run 913 * through the flushing state machine skip ALLOC_CHUNK_FORCE and 914 * commit the transaction. If nothing has changed the next go 915 * around then we can force a chunk allocation. 916 */ 917 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles) 918 flush_state++; 919 920 if (flush_state > COMMIT_TRANS) { 921 commit_cycles++; 922 if (commit_cycles > 2) { 923 if (maybe_fail_all_tickets(fs_info, space_info)) { 924 flush_state = FLUSH_DELAYED_ITEMS_NR; 925 commit_cycles--; 926 } else { 927 space_info->flush = 0; 928 } 929 } else { 930 flush_state = FLUSH_DELAYED_ITEMS_NR; 931 } 932 } 933 spin_unlock(&space_info->lock); 934 } while (flush_state <= COMMIT_TRANS); 935 } 936 937 /* 938 * This handles pre-flushing of metadata space before we get to the point that 939 * we need to start blocking threads on tickets. The logic here is different 940 * from the other flush paths because it doesn't rely on tickets to tell us how 941 * much we need to flush, instead it attempts to keep us below the 80% full 942 * watermark of space by flushing whichever reservation pool is currently the 943 * largest. 944 */ 945 static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work) 946 { 947 struct btrfs_fs_info *fs_info; 948 struct btrfs_space_info *space_info; 949 struct btrfs_block_rsv *delayed_block_rsv; 950 struct btrfs_block_rsv *delayed_refs_rsv; 951 struct btrfs_block_rsv *global_rsv; 952 struct btrfs_block_rsv *trans_rsv; 953 int loops = 0; 954 955 fs_info = container_of(work, struct btrfs_fs_info, 956 preempt_reclaim_work); 957 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); 958 delayed_block_rsv = &fs_info->delayed_block_rsv; 959 delayed_refs_rsv = &fs_info->delayed_refs_rsv; 960 global_rsv = &fs_info->global_block_rsv; 961 trans_rsv = &fs_info->trans_block_rsv; 962 963 spin_lock(&space_info->lock); 964 while (need_preemptive_reclaim(fs_info, space_info)) { 965 enum btrfs_flush_state flush; 966 u64 delalloc_size = 0; 967 u64 to_reclaim, block_rsv_size; 968 u64 global_rsv_size = global_rsv->reserved; 969 970 loops++; 971 972 /* 973 * We don't have a precise counter for the metadata being 974 * reserved for delalloc, so we'll approximate it by subtracting 975 * out the block rsv's space from the bytes_may_use. If that 976 * amount is higher than the individual reserves, then we can 977 * assume it's tied up in delalloc reservations. 978 */ 979 block_rsv_size = global_rsv_size + 980 delayed_block_rsv->reserved + 981 delayed_refs_rsv->reserved + 982 trans_rsv->reserved; 983 if (block_rsv_size < space_info->bytes_may_use) 984 delalloc_size = space_info->bytes_may_use - block_rsv_size; 985 spin_unlock(&space_info->lock); 986 987 /* 988 * We don't want to include the global_rsv in our calculation, 989 * because that's space we can't touch. Subtract it from the 990 * block_rsv_size for the next checks. 991 */ 992 block_rsv_size -= global_rsv_size; 993 994 /* 995 * We really want to avoid flushing delalloc too much, as it 996 * could result in poor allocation patterns, so only flush it if 997 * it's larger than the rest of the pools combined. 998 */ 999 if (delalloc_size > block_rsv_size) { 1000 to_reclaim = delalloc_size; 1001 flush = FLUSH_DELALLOC; 1002 } else if (space_info->bytes_pinned > 1003 (delayed_block_rsv->reserved + 1004 delayed_refs_rsv->reserved)) { 1005 to_reclaim = space_info->bytes_pinned; 1006 flush = COMMIT_TRANS; 1007 } else if (delayed_block_rsv->reserved > 1008 delayed_refs_rsv->reserved) { 1009 to_reclaim = delayed_block_rsv->reserved; 1010 flush = FLUSH_DELAYED_ITEMS_NR; 1011 } else { 1012 to_reclaim = delayed_refs_rsv->reserved; 1013 flush = FLUSH_DELAYED_REFS_NR; 1014 } 1015 1016 /* 1017 * We don't want to reclaim everything, just a portion, so scale 1018 * down the to_reclaim by 1/4. If it takes us down to 0, 1019 * reclaim 1 items worth. 1020 */ 1021 to_reclaim >>= 2; 1022 if (!to_reclaim) 1023 to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1); 1024 flush_space(fs_info, space_info, to_reclaim, flush, true); 1025 cond_resched(); 1026 spin_lock(&space_info->lock); 1027 } 1028 1029 /* We only went through once, back off our clamping. */ 1030 if (loops == 1 && !space_info->reclaim_size) 1031 space_info->clamp = max(1, space_info->clamp - 1); 1032 trace_btrfs_done_preemptive_reclaim(fs_info, space_info); 1033 spin_unlock(&space_info->lock); 1034 } 1035 1036 /* 1037 * FLUSH_DELALLOC_WAIT: 1038 * Space is freed from flushing delalloc in one of two ways. 1039 * 1040 * 1) compression is on and we allocate less space than we reserved 1041 * 2) we are overwriting existing space 1042 * 1043 * For #1 that extra space is reclaimed as soon as the delalloc pages are 1044 * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent 1045 * length to ->bytes_reserved, and subtracts the reserved space from 1046 * ->bytes_may_use. 1047 * 1048 * For #2 this is trickier. Once the ordered extent runs we will drop the 1049 * extent in the range we are overwriting, which creates a delayed ref for 1050 * that freed extent. This however is not reclaimed until the transaction 1051 * commits, thus the next stages. 1052 * 1053 * RUN_DELAYED_IPUTS 1054 * If we are freeing inodes, we want to make sure all delayed iputs have 1055 * completed, because they could have been on an inode with i_nlink == 0, and 1056 * thus have been truncated and freed up space. But again this space is not 1057 * immediately re-usable, it comes in the form of a delayed ref, which must be 1058 * run and then the transaction must be committed. 1059 * 1060 * COMMIT_TRANS 1061 * This is where we reclaim all of the pinned space generated by running the 1062 * iputs 1063 * 1064 * ALLOC_CHUNK_FORCE 1065 * For data we start with alloc chunk force, however we could have been full 1066 * before, and then the transaction commit could have freed new block groups, 1067 * so if we now have space to allocate do the force chunk allocation. 1068 */ 1069 static const enum btrfs_flush_state data_flush_states[] = { 1070 FLUSH_DELALLOC_WAIT, 1071 RUN_DELAYED_IPUTS, 1072 COMMIT_TRANS, 1073 ALLOC_CHUNK_FORCE, 1074 }; 1075 1076 static void btrfs_async_reclaim_data_space(struct work_struct *work) 1077 { 1078 struct btrfs_fs_info *fs_info; 1079 struct btrfs_space_info *space_info; 1080 u64 last_tickets_id; 1081 enum btrfs_flush_state flush_state = 0; 1082 1083 fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work); 1084 space_info = fs_info->data_sinfo; 1085 1086 spin_lock(&space_info->lock); 1087 if (list_empty(&space_info->tickets)) { 1088 space_info->flush = 0; 1089 spin_unlock(&space_info->lock); 1090 return; 1091 } 1092 last_tickets_id = space_info->tickets_id; 1093 spin_unlock(&space_info->lock); 1094 1095 while (!space_info->full) { 1096 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); 1097 spin_lock(&space_info->lock); 1098 if (list_empty(&space_info->tickets)) { 1099 space_info->flush = 0; 1100 spin_unlock(&space_info->lock); 1101 return; 1102 } 1103 last_tickets_id = space_info->tickets_id; 1104 spin_unlock(&space_info->lock); 1105 } 1106 1107 while (flush_state < ARRAY_SIZE(data_flush_states)) { 1108 flush_space(fs_info, space_info, U64_MAX, 1109 data_flush_states[flush_state], false); 1110 spin_lock(&space_info->lock); 1111 if (list_empty(&space_info->tickets)) { 1112 space_info->flush = 0; 1113 spin_unlock(&space_info->lock); 1114 return; 1115 } 1116 1117 if (last_tickets_id == space_info->tickets_id) { 1118 flush_state++; 1119 } else { 1120 last_tickets_id = space_info->tickets_id; 1121 flush_state = 0; 1122 } 1123 1124 if (flush_state >= ARRAY_SIZE(data_flush_states)) { 1125 if (space_info->full) { 1126 if (maybe_fail_all_tickets(fs_info, space_info)) 1127 flush_state = 0; 1128 else 1129 space_info->flush = 0; 1130 } else { 1131 flush_state = 0; 1132 } 1133 } 1134 spin_unlock(&space_info->lock); 1135 } 1136 } 1137 1138 void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info) 1139 { 1140 INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space); 1141 INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space); 1142 INIT_WORK(&fs_info->preempt_reclaim_work, 1143 btrfs_preempt_reclaim_metadata_space); 1144 } 1145 1146 static const enum btrfs_flush_state priority_flush_states[] = { 1147 FLUSH_DELAYED_ITEMS_NR, 1148 FLUSH_DELAYED_ITEMS, 1149 ALLOC_CHUNK, 1150 }; 1151 1152 static const enum btrfs_flush_state evict_flush_states[] = { 1153 FLUSH_DELAYED_ITEMS_NR, 1154 FLUSH_DELAYED_ITEMS, 1155 FLUSH_DELAYED_REFS_NR, 1156 FLUSH_DELAYED_REFS, 1157 FLUSH_DELALLOC, 1158 FLUSH_DELALLOC_WAIT, 1159 ALLOC_CHUNK, 1160 COMMIT_TRANS, 1161 }; 1162 1163 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info, 1164 struct btrfs_space_info *space_info, 1165 struct reserve_ticket *ticket, 1166 const enum btrfs_flush_state *states, 1167 int states_nr) 1168 { 1169 u64 to_reclaim; 1170 int flush_state; 1171 1172 spin_lock(&space_info->lock); 1173 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); 1174 if (!to_reclaim) { 1175 spin_unlock(&space_info->lock); 1176 return; 1177 } 1178 spin_unlock(&space_info->lock); 1179 1180 flush_state = 0; 1181 do { 1182 flush_space(fs_info, space_info, to_reclaim, states[flush_state], 1183 false); 1184 flush_state++; 1185 spin_lock(&space_info->lock); 1186 if (ticket->bytes == 0) { 1187 spin_unlock(&space_info->lock); 1188 return; 1189 } 1190 spin_unlock(&space_info->lock); 1191 } while (flush_state < states_nr); 1192 } 1193 1194 static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info, 1195 struct btrfs_space_info *space_info, 1196 struct reserve_ticket *ticket) 1197 { 1198 while (!space_info->full) { 1199 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); 1200 spin_lock(&space_info->lock); 1201 if (ticket->bytes == 0) { 1202 spin_unlock(&space_info->lock); 1203 return; 1204 } 1205 spin_unlock(&space_info->lock); 1206 } 1207 } 1208 1209 static void wait_reserve_ticket(struct btrfs_fs_info *fs_info, 1210 struct btrfs_space_info *space_info, 1211 struct reserve_ticket *ticket) 1212 1213 { 1214 DEFINE_WAIT(wait); 1215 int ret = 0; 1216 1217 spin_lock(&space_info->lock); 1218 while (ticket->bytes > 0 && ticket->error == 0) { 1219 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE); 1220 if (ret) { 1221 /* 1222 * Delete us from the list. After we unlock the space 1223 * info, we don't want the async reclaim job to reserve 1224 * space for this ticket. If that would happen, then the 1225 * ticket's task would not known that space was reserved 1226 * despite getting an error, resulting in a space leak 1227 * (bytes_may_use counter of our space_info). 1228 */ 1229 remove_ticket(space_info, ticket); 1230 ticket->error = -EINTR; 1231 break; 1232 } 1233 spin_unlock(&space_info->lock); 1234 1235 schedule(); 1236 1237 finish_wait(&ticket->wait, &wait); 1238 spin_lock(&space_info->lock); 1239 } 1240 spin_unlock(&space_info->lock); 1241 } 1242 1243 /** 1244 * Do the appropriate flushing and waiting for a ticket 1245 * 1246 * @fs_info: the filesystem 1247 * @space_info: space info for the reservation 1248 * @ticket: ticket for the reservation 1249 * @start_ns: timestamp when the reservation started 1250 * @orig_bytes: amount of bytes originally reserved 1251 * @flush: how much we can flush 1252 * 1253 * This does the work of figuring out how to flush for the ticket, waiting for 1254 * the reservation, and returning the appropriate error if there is one. 1255 */ 1256 static int handle_reserve_ticket(struct btrfs_fs_info *fs_info, 1257 struct btrfs_space_info *space_info, 1258 struct reserve_ticket *ticket, 1259 u64 start_ns, u64 orig_bytes, 1260 enum btrfs_reserve_flush_enum flush) 1261 { 1262 int ret; 1263 1264 switch (flush) { 1265 case BTRFS_RESERVE_FLUSH_DATA: 1266 case BTRFS_RESERVE_FLUSH_ALL: 1267 case BTRFS_RESERVE_FLUSH_ALL_STEAL: 1268 wait_reserve_ticket(fs_info, space_info, ticket); 1269 break; 1270 case BTRFS_RESERVE_FLUSH_LIMIT: 1271 priority_reclaim_metadata_space(fs_info, space_info, ticket, 1272 priority_flush_states, 1273 ARRAY_SIZE(priority_flush_states)); 1274 break; 1275 case BTRFS_RESERVE_FLUSH_EVICT: 1276 priority_reclaim_metadata_space(fs_info, space_info, ticket, 1277 evict_flush_states, 1278 ARRAY_SIZE(evict_flush_states)); 1279 break; 1280 case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE: 1281 priority_reclaim_data_space(fs_info, space_info, ticket); 1282 break; 1283 default: 1284 ASSERT(0); 1285 break; 1286 } 1287 1288 spin_lock(&space_info->lock); 1289 ret = ticket->error; 1290 if (ticket->bytes || ticket->error) { 1291 /* 1292 * We were a priority ticket, so we need to delete ourselves 1293 * from the list. Because we could have other priority tickets 1294 * behind us that require less space, run 1295 * btrfs_try_granting_tickets() to see if their reservations can 1296 * now be made. 1297 */ 1298 if (!list_empty(&ticket->list)) { 1299 remove_ticket(space_info, ticket); 1300 btrfs_try_granting_tickets(fs_info, space_info); 1301 } 1302 1303 if (!ret) 1304 ret = -ENOSPC; 1305 } 1306 spin_unlock(&space_info->lock); 1307 ASSERT(list_empty(&ticket->list)); 1308 /* 1309 * Check that we can't have an error set if the reservation succeeded, 1310 * as that would confuse tasks and lead them to error out without 1311 * releasing reserved space (if an error happens the expectation is that 1312 * space wasn't reserved at all). 1313 */ 1314 ASSERT(!(ticket->bytes == 0 && ticket->error)); 1315 trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes, 1316 start_ns, flush, ticket->error); 1317 return ret; 1318 } 1319 1320 /* 1321 * This returns true if this flush state will go through the ordinary flushing 1322 * code. 1323 */ 1324 static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush) 1325 { 1326 return (flush == BTRFS_RESERVE_FLUSH_ALL) || 1327 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); 1328 } 1329 1330 static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info, 1331 struct btrfs_space_info *space_info) 1332 { 1333 u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes); 1334 u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes); 1335 1336 /* 1337 * If we're heavy on ordered operations then clamping won't help us. We 1338 * need to clamp specifically to keep up with dirty'ing buffered 1339 * writers, because there's not a 1:1 correlation of writing delalloc 1340 * and freeing space, like there is with flushing delayed refs or 1341 * delayed nodes. If we're already more ordered than delalloc then 1342 * we're keeping up, otherwise we aren't and should probably clamp. 1343 */ 1344 if (ordered < delalloc) 1345 space_info->clamp = min(space_info->clamp + 1, 8); 1346 } 1347 1348 /** 1349 * Try to reserve bytes from the block_rsv's space 1350 * 1351 * @fs_info: the filesystem 1352 * @space_info: space info we want to allocate from 1353 * @orig_bytes: number of bytes we want 1354 * @flush: whether or not we can flush to make our reservation 1355 * 1356 * This will reserve orig_bytes number of bytes from the space info associated 1357 * with the block_rsv. If there is not enough space it will make an attempt to 1358 * flush out space to make room. It will do this by flushing delalloc if 1359 * possible or committing the transaction. If flush is 0 then no attempts to 1360 * regain reservations will be made and this will fail if there is not enough 1361 * space already. 1362 */ 1363 static int __reserve_bytes(struct btrfs_fs_info *fs_info, 1364 struct btrfs_space_info *space_info, u64 orig_bytes, 1365 enum btrfs_reserve_flush_enum flush) 1366 { 1367 struct work_struct *async_work; 1368 struct reserve_ticket ticket; 1369 u64 start_ns = 0; 1370 u64 used; 1371 int ret = 0; 1372 bool pending_tickets; 1373 1374 ASSERT(orig_bytes); 1375 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL); 1376 1377 if (flush == BTRFS_RESERVE_FLUSH_DATA) 1378 async_work = &fs_info->async_data_reclaim_work; 1379 else 1380 async_work = &fs_info->async_reclaim_work; 1381 1382 spin_lock(&space_info->lock); 1383 ret = -ENOSPC; 1384 used = btrfs_space_info_used(space_info, true); 1385 1386 /* 1387 * We don't want NO_FLUSH allocations to jump everybody, they can 1388 * generally handle ENOSPC in a different way, so treat them the same as 1389 * normal flushers when it comes to skipping pending tickets. 1390 */ 1391 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH)) 1392 pending_tickets = !list_empty(&space_info->tickets) || 1393 !list_empty(&space_info->priority_tickets); 1394 else 1395 pending_tickets = !list_empty(&space_info->priority_tickets); 1396 1397 /* 1398 * Carry on if we have enough space (short-circuit) OR call 1399 * can_overcommit() to ensure we can overcommit to continue. 1400 */ 1401 if (!pending_tickets && 1402 ((used + orig_bytes <= space_info->total_bytes) || 1403 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) { 1404 btrfs_space_info_update_bytes_may_use(fs_info, space_info, 1405 orig_bytes); 1406 ret = 0; 1407 } 1408 1409 /* 1410 * If we couldn't make a reservation then setup our reservation ticket 1411 * and kick the async worker if it's not already running. 1412 * 1413 * If we are a priority flusher then we just need to add our ticket to 1414 * the list and we will do our own flushing further down. 1415 */ 1416 if (ret && flush != BTRFS_RESERVE_NO_FLUSH) { 1417 ticket.bytes = orig_bytes; 1418 ticket.error = 0; 1419 space_info->reclaim_size += ticket.bytes; 1420 init_waitqueue_head(&ticket.wait); 1421 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); 1422 if (trace_btrfs_reserve_ticket_enabled()) 1423 start_ns = ktime_get_ns(); 1424 1425 if (flush == BTRFS_RESERVE_FLUSH_ALL || 1426 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL || 1427 flush == BTRFS_RESERVE_FLUSH_DATA) { 1428 list_add_tail(&ticket.list, &space_info->tickets); 1429 if (!space_info->flush) { 1430 /* 1431 * We were forced to add a reserve ticket, so 1432 * our preemptive flushing is unable to keep 1433 * up. Clamp down on the threshold for the 1434 * preemptive flushing in order to keep up with 1435 * the workload. 1436 */ 1437 maybe_clamp_preempt(fs_info, space_info); 1438 1439 space_info->flush = 1; 1440 trace_btrfs_trigger_flush(fs_info, 1441 space_info->flags, 1442 orig_bytes, flush, 1443 "enospc"); 1444 queue_work(system_unbound_wq, async_work); 1445 } 1446 } else { 1447 list_add_tail(&ticket.list, 1448 &space_info->priority_tickets); 1449 } 1450 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) { 1451 used += orig_bytes; 1452 /* 1453 * We will do the space reservation dance during log replay, 1454 * which means we won't have fs_info->fs_root set, so don't do 1455 * the async reclaim as we will panic. 1456 */ 1457 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) && 1458 !work_busy(&fs_info->preempt_reclaim_work) && 1459 need_preemptive_reclaim(fs_info, space_info)) { 1460 trace_btrfs_trigger_flush(fs_info, space_info->flags, 1461 orig_bytes, flush, "preempt"); 1462 queue_work(system_unbound_wq, 1463 &fs_info->preempt_reclaim_work); 1464 } 1465 } 1466 spin_unlock(&space_info->lock); 1467 if (!ret || flush == BTRFS_RESERVE_NO_FLUSH) 1468 return ret; 1469 1470 return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns, 1471 orig_bytes, flush); 1472 } 1473 1474 /** 1475 * Trye to reserve metadata bytes from the block_rsv's space 1476 * 1477 * @root: the root we're allocating for 1478 * @block_rsv: block_rsv we're allocating for 1479 * @orig_bytes: number of bytes we want 1480 * @flush: whether or not we can flush to make our reservation 1481 * 1482 * This will reserve orig_bytes number of bytes from the space info associated 1483 * with the block_rsv. If there is not enough space it will make an attempt to 1484 * flush out space to make room. It will do this by flushing delalloc if 1485 * possible or committing the transaction. If flush is 0 then no attempts to 1486 * regain reservations will be made and this will fail if there is not enough 1487 * space already. 1488 */ 1489 int btrfs_reserve_metadata_bytes(struct btrfs_root *root, 1490 struct btrfs_block_rsv *block_rsv, 1491 u64 orig_bytes, 1492 enum btrfs_reserve_flush_enum flush) 1493 { 1494 struct btrfs_fs_info *fs_info = root->fs_info; 1495 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv; 1496 int ret; 1497 1498 ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush); 1499 if (ret == -ENOSPC && 1500 unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) { 1501 if (block_rsv != global_rsv && 1502 !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes)) 1503 ret = 0; 1504 } 1505 if (ret == -ENOSPC) { 1506 trace_btrfs_space_reservation(fs_info, "space_info:enospc", 1507 block_rsv->space_info->flags, 1508 orig_bytes, 1); 1509 1510 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 1511 btrfs_dump_space_info(fs_info, block_rsv->space_info, 1512 orig_bytes, 0); 1513 } 1514 return ret; 1515 } 1516 1517 /** 1518 * Try to reserve data bytes for an allocation 1519 * 1520 * @fs_info: the filesystem 1521 * @bytes: number of bytes we need 1522 * @flush: how we are allowed to flush 1523 * 1524 * This will reserve bytes from the data space info. If there is not enough 1525 * space then we will attempt to flush space as specified by flush. 1526 */ 1527 int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes, 1528 enum btrfs_reserve_flush_enum flush) 1529 { 1530 struct btrfs_space_info *data_sinfo = fs_info->data_sinfo; 1531 int ret; 1532 1533 ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA || 1534 flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE); 1535 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA); 1536 1537 ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush); 1538 if (ret == -ENOSPC) { 1539 trace_btrfs_space_reservation(fs_info, "space_info:enospc", 1540 data_sinfo->flags, bytes, 1); 1541 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 1542 btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0); 1543 } 1544 return ret; 1545 } 1546