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 * may_commit_transaction() is the ultimate arbiter on whether we commit the 137 * transaction or not. In order to avoid constantly churning we do all the 138 * above flushing first and then commit the transaction as the last resort. 139 * However we need to take into account things like pinned space that would 140 * be freed, plus any delayed work we may not have gotten rid of in the case 141 * of metadata. 142 * 143 * FORCE_COMMIT_TRANS 144 * For use by the preemptive flusher. We use this to bypass the ticketing 145 * checks in may_commit_transaction, as we have more information about the 146 * overall state of the system and may want to commit the transaction ahead 147 * of actual ENOSPC conditions. 148 * 149 * OVERCOMMIT 150 * 151 * Because we hold so many reservations for metadata we will allow you to 152 * reserve more space than is currently free in the currently allocate 153 * metadata space. This only happens with metadata, data does not allow 154 * overcommitting. 155 * 156 * You can see the current logic for when we allow overcommit in 157 * btrfs_can_overcommit(), but it only applies to unallocated space. If there 158 * is no unallocated space to be had, all reservations are kept within the 159 * free space in the allocated metadata chunks. 160 * 161 * Because of overcommitting, you generally want to use the 162 * btrfs_can_overcommit() logic for metadata allocations, as it does the right 163 * thing with or without extra unallocated space. 164 */ 165 166 u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info, 167 bool may_use_included) 168 { 169 ASSERT(s_info); 170 return s_info->bytes_used + s_info->bytes_reserved + 171 s_info->bytes_pinned + s_info->bytes_readonly + 172 s_info->bytes_zone_unusable + 173 (may_use_included ? s_info->bytes_may_use : 0); 174 } 175 176 /* 177 * after adding space to the filesystem, we need to clear the full flags 178 * on all the space infos. 179 */ 180 void btrfs_clear_space_info_full(struct btrfs_fs_info *info) 181 { 182 struct list_head *head = &info->space_info; 183 struct btrfs_space_info *found; 184 185 list_for_each_entry(found, head, list) 186 found->full = 0; 187 } 188 189 static int create_space_info(struct btrfs_fs_info *info, u64 flags) 190 { 191 192 struct btrfs_space_info *space_info; 193 int i; 194 int ret; 195 196 space_info = kzalloc(sizeof(*space_info), GFP_NOFS); 197 if (!space_info) 198 return -ENOMEM; 199 200 ret = percpu_counter_init(&space_info->total_bytes_pinned, 0, 201 GFP_KERNEL); 202 if (ret) { 203 kfree(space_info); 204 return ret; 205 } 206 207 for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) 208 INIT_LIST_HEAD(&space_info->block_groups[i]); 209 init_rwsem(&space_info->groups_sem); 210 spin_lock_init(&space_info->lock); 211 space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK; 212 space_info->force_alloc = CHUNK_ALLOC_NO_FORCE; 213 INIT_LIST_HEAD(&space_info->ro_bgs); 214 INIT_LIST_HEAD(&space_info->tickets); 215 INIT_LIST_HEAD(&space_info->priority_tickets); 216 space_info->clamp = 1; 217 218 ret = btrfs_sysfs_add_space_info_type(info, space_info); 219 if (ret) 220 return ret; 221 222 list_add(&space_info->list, &info->space_info); 223 if (flags & BTRFS_BLOCK_GROUP_DATA) 224 info->data_sinfo = space_info; 225 226 return ret; 227 } 228 229 int btrfs_init_space_info(struct btrfs_fs_info *fs_info) 230 { 231 struct btrfs_super_block *disk_super; 232 u64 features; 233 u64 flags; 234 int mixed = 0; 235 int ret; 236 237 disk_super = fs_info->super_copy; 238 if (!btrfs_super_root(disk_super)) 239 return -EINVAL; 240 241 features = btrfs_super_incompat_flags(disk_super); 242 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS) 243 mixed = 1; 244 245 flags = BTRFS_BLOCK_GROUP_SYSTEM; 246 ret = create_space_info(fs_info, flags); 247 if (ret) 248 goto out; 249 250 if (mixed) { 251 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA; 252 ret = create_space_info(fs_info, flags); 253 } else { 254 flags = BTRFS_BLOCK_GROUP_METADATA; 255 ret = create_space_info(fs_info, flags); 256 if (ret) 257 goto out; 258 259 flags = BTRFS_BLOCK_GROUP_DATA; 260 ret = create_space_info(fs_info, flags); 261 } 262 out: 263 return ret; 264 } 265 266 void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags, 267 u64 total_bytes, u64 bytes_used, 268 u64 bytes_readonly, u64 bytes_zone_unusable, 269 struct btrfs_space_info **space_info) 270 { 271 struct btrfs_space_info *found; 272 int factor; 273 274 factor = btrfs_bg_type_to_factor(flags); 275 276 found = btrfs_find_space_info(info, flags); 277 ASSERT(found); 278 spin_lock(&found->lock); 279 found->total_bytes += total_bytes; 280 found->disk_total += total_bytes * factor; 281 found->bytes_used += bytes_used; 282 found->disk_used += bytes_used * factor; 283 found->bytes_readonly += bytes_readonly; 284 found->bytes_zone_unusable += bytes_zone_unusable; 285 if (total_bytes > 0) 286 found->full = 0; 287 btrfs_try_granting_tickets(info, found); 288 spin_unlock(&found->lock); 289 *space_info = found; 290 } 291 292 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info, 293 u64 flags) 294 { 295 struct list_head *head = &info->space_info; 296 struct btrfs_space_info *found; 297 298 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK; 299 300 list_for_each_entry(found, head, list) { 301 if (found->flags & flags) 302 return found; 303 } 304 return NULL; 305 } 306 307 static u64 calc_available_free_space(struct btrfs_fs_info *fs_info, 308 struct btrfs_space_info *space_info, 309 enum btrfs_reserve_flush_enum flush) 310 { 311 u64 profile; 312 u64 avail; 313 int factor; 314 315 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM) 316 profile = btrfs_system_alloc_profile(fs_info); 317 else 318 profile = btrfs_metadata_alloc_profile(fs_info); 319 320 avail = atomic64_read(&fs_info->free_chunk_space); 321 322 /* 323 * If we have dup, raid1 or raid10 then only half of the free 324 * space is actually usable. For raid56, the space info used 325 * doesn't include the parity drive, so we don't have to 326 * change the math 327 */ 328 factor = btrfs_bg_type_to_factor(profile); 329 avail = div_u64(avail, factor); 330 331 /* 332 * If we aren't flushing all things, let us overcommit up to 333 * 1/2th of the space. If we can flush, don't let us overcommit 334 * too much, let it overcommit up to 1/8 of the space. 335 */ 336 if (flush == BTRFS_RESERVE_FLUSH_ALL) 337 avail >>= 3; 338 else 339 avail >>= 1; 340 return avail; 341 } 342 343 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info, 344 struct btrfs_space_info *space_info, u64 bytes, 345 enum btrfs_reserve_flush_enum flush) 346 { 347 u64 avail; 348 u64 used; 349 350 /* Don't overcommit when in mixed mode */ 351 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA) 352 return 0; 353 354 used = btrfs_space_info_used(space_info, true); 355 avail = calc_available_free_space(fs_info, space_info, flush); 356 357 if (used + bytes < space_info->total_bytes + avail) 358 return 1; 359 return 0; 360 } 361 362 static void remove_ticket(struct btrfs_space_info *space_info, 363 struct reserve_ticket *ticket) 364 { 365 if (!list_empty(&ticket->list)) { 366 list_del_init(&ticket->list); 367 ASSERT(space_info->reclaim_size >= ticket->bytes); 368 space_info->reclaim_size -= ticket->bytes; 369 } 370 } 371 372 /* 373 * This is for space we already have accounted in space_info->bytes_may_use, so 374 * basically when we're returning space from block_rsv's. 375 */ 376 void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info, 377 struct btrfs_space_info *space_info) 378 { 379 struct list_head *head; 380 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH; 381 382 lockdep_assert_held(&space_info->lock); 383 384 head = &space_info->priority_tickets; 385 again: 386 while (!list_empty(head)) { 387 struct reserve_ticket *ticket; 388 u64 used = btrfs_space_info_used(space_info, true); 389 390 ticket = list_first_entry(head, struct reserve_ticket, list); 391 392 /* Check and see if our ticket can be satisfied now. */ 393 if ((used + ticket->bytes <= space_info->total_bytes) || 394 btrfs_can_overcommit(fs_info, space_info, ticket->bytes, 395 flush)) { 396 btrfs_space_info_update_bytes_may_use(fs_info, 397 space_info, 398 ticket->bytes); 399 remove_ticket(space_info, ticket); 400 ticket->bytes = 0; 401 space_info->tickets_id++; 402 wake_up(&ticket->wait); 403 } else { 404 break; 405 } 406 } 407 408 if (head == &space_info->priority_tickets) { 409 head = &space_info->tickets; 410 flush = BTRFS_RESERVE_FLUSH_ALL; 411 goto again; 412 } 413 } 414 415 #define DUMP_BLOCK_RSV(fs_info, rsv_name) \ 416 do { \ 417 struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \ 418 spin_lock(&__rsv->lock); \ 419 btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \ 420 __rsv->size, __rsv->reserved); \ 421 spin_unlock(&__rsv->lock); \ 422 } while (0) 423 424 static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info, 425 struct btrfs_space_info *info) 426 { 427 lockdep_assert_held(&info->lock); 428 429 btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull", 430 info->flags, 431 info->total_bytes - btrfs_space_info_used(info, true), 432 info->full ? "" : "not "); 433 btrfs_info(fs_info, 434 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu", 435 info->total_bytes, info->bytes_used, info->bytes_pinned, 436 info->bytes_reserved, info->bytes_may_use, 437 info->bytes_readonly, info->bytes_zone_unusable); 438 439 DUMP_BLOCK_RSV(fs_info, global_block_rsv); 440 DUMP_BLOCK_RSV(fs_info, trans_block_rsv); 441 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv); 442 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv); 443 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv); 444 445 } 446 447 void btrfs_dump_space_info(struct btrfs_fs_info *fs_info, 448 struct btrfs_space_info *info, u64 bytes, 449 int dump_block_groups) 450 { 451 struct btrfs_block_group *cache; 452 int index = 0; 453 454 spin_lock(&info->lock); 455 __btrfs_dump_space_info(fs_info, info); 456 spin_unlock(&info->lock); 457 458 if (!dump_block_groups) 459 return; 460 461 down_read(&info->groups_sem); 462 again: 463 list_for_each_entry(cache, &info->block_groups[index], list) { 464 spin_lock(&cache->lock); 465 btrfs_info(fs_info, 466 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu zone_unusable %s", 467 cache->start, cache->length, cache->used, cache->pinned, 468 cache->reserved, cache->zone_unusable, 469 cache->ro ? "[readonly]" : ""); 470 spin_unlock(&cache->lock); 471 btrfs_dump_free_space(cache, bytes); 472 } 473 if (++index < BTRFS_NR_RAID_TYPES) 474 goto again; 475 up_read(&info->groups_sem); 476 } 477 478 static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info, 479 u64 to_reclaim) 480 { 481 u64 bytes; 482 u64 nr; 483 484 bytes = btrfs_calc_insert_metadata_size(fs_info, 1); 485 nr = div64_u64(to_reclaim, bytes); 486 if (!nr) 487 nr = 1; 488 return nr; 489 } 490 491 #define EXTENT_SIZE_PER_ITEM SZ_256K 492 493 /* 494 * shrink metadata reservation for delalloc 495 */ 496 static void shrink_delalloc(struct btrfs_fs_info *fs_info, 497 struct btrfs_space_info *space_info, 498 u64 to_reclaim, bool wait_ordered, 499 bool for_preempt) 500 { 501 struct btrfs_trans_handle *trans; 502 u64 delalloc_bytes; 503 u64 ordered_bytes; 504 u64 items; 505 long time_left; 506 int loops; 507 508 /* Calc the number of the pages we need flush for space reservation */ 509 if (to_reclaim == U64_MAX) { 510 items = U64_MAX; 511 } else { 512 /* 513 * to_reclaim is set to however much metadata we need to 514 * reclaim, but reclaiming that much data doesn't really track 515 * exactly, so increase the amount to reclaim by 2x in order to 516 * make sure we're flushing enough delalloc to hopefully reclaim 517 * some metadata reservations. 518 */ 519 items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2; 520 to_reclaim = items * EXTENT_SIZE_PER_ITEM; 521 } 522 523 trans = (struct btrfs_trans_handle *)current->journal_info; 524 525 delalloc_bytes = percpu_counter_sum_positive( 526 &fs_info->delalloc_bytes); 527 ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes); 528 if (delalloc_bytes == 0 && ordered_bytes == 0) 529 return; 530 531 /* 532 * If we are doing more ordered than delalloc we need to just wait on 533 * ordered extents, otherwise we'll waste time trying to flush delalloc 534 * that likely won't give us the space back we need. 535 */ 536 if (ordered_bytes > delalloc_bytes && !for_preempt) 537 wait_ordered = true; 538 539 loops = 0; 540 while ((delalloc_bytes || ordered_bytes) && loops < 3) { 541 u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT; 542 long nr_pages = min_t(u64, temp, LONG_MAX); 543 544 btrfs_start_delalloc_roots(fs_info, nr_pages, true); 545 546 loops++; 547 if (wait_ordered && !trans) { 548 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1); 549 } else { 550 time_left = schedule_timeout_killable(1); 551 if (time_left) 552 break; 553 } 554 555 /* 556 * If we are for preemption we just want a one-shot of delalloc 557 * flushing so we can stop flushing if we decide we don't need 558 * to anymore. 559 */ 560 if (for_preempt) 561 break; 562 563 spin_lock(&space_info->lock); 564 if (list_empty(&space_info->tickets) && 565 list_empty(&space_info->priority_tickets)) { 566 spin_unlock(&space_info->lock); 567 break; 568 } 569 spin_unlock(&space_info->lock); 570 571 delalloc_bytes = percpu_counter_sum_positive( 572 &fs_info->delalloc_bytes); 573 ordered_bytes = percpu_counter_sum_positive( 574 &fs_info->ordered_bytes); 575 } 576 } 577 578 /** 579 * Possibly commit the transaction if its ok to 580 * 581 * @fs_info: the filesystem 582 * @space_info: space_info we are checking for commit, either data or metadata 583 * 584 * This will check to make sure that committing the transaction will actually 585 * get us somewhere and then commit the transaction if it does. Otherwise it 586 * will return -ENOSPC. 587 */ 588 static int may_commit_transaction(struct btrfs_fs_info *fs_info, 589 struct btrfs_space_info *space_info) 590 { 591 struct reserve_ticket *ticket = NULL; 592 struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv; 593 struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv; 594 struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv; 595 struct btrfs_trans_handle *trans; 596 u64 reclaim_bytes = 0; 597 u64 bytes_needed = 0; 598 u64 cur_free_bytes = 0; 599 600 trans = (struct btrfs_trans_handle *)current->journal_info; 601 if (trans) 602 return -EAGAIN; 603 604 spin_lock(&space_info->lock); 605 cur_free_bytes = btrfs_space_info_used(space_info, true); 606 if (cur_free_bytes < space_info->total_bytes) 607 cur_free_bytes = space_info->total_bytes - cur_free_bytes; 608 else 609 cur_free_bytes = 0; 610 611 if (!list_empty(&space_info->priority_tickets)) 612 ticket = list_first_entry(&space_info->priority_tickets, 613 struct reserve_ticket, list); 614 else if (!list_empty(&space_info->tickets)) 615 ticket = list_first_entry(&space_info->tickets, 616 struct reserve_ticket, list); 617 if (ticket) 618 bytes_needed = ticket->bytes; 619 620 if (bytes_needed > cur_free_bytes) 621 bytes_needed -= cur_free_bytes; 622 else 623 bytes_needed = 0; 624 spin_unlock(&space_info->lock); 625 626 if (!bytes_needed) 627 return 0; 628 629 trans = btrfs_join_transaction(fs_info->extent_root); 630 if (IS_ERR(trans)) 631 return PTR_ERR(trans); 632 633 /* 634 * See if there is enough pinned space to make this reservation, or if 635 * we have block groups that are going to be freed, allowing us to 636 * possibly do a chunk allocation the next loop through. 637 */ 638 if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags) || 639 __percpu_counter_compare(&space_info->total_bytes_pinned, 640 bytes_needed, 641 BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0) 642 goto commit; 643 644 /* 645 * See if there is some space in the delayed insertion reserve for this 646 * reservation. If the space_info's don't match (like for DATA or 647 * SYSTEM) then just go enospc, reclaiming this space won't recover any 648 * space to satisfy those reservations. 649 */ 650 if (space_info != delayed_rsv->space_info) 651 goto enospc; 652 653 spin_lock(&delayed_rsv->lock); 654 reclaim_bytes += delayed_rsv->reserved; 655 spin_unlock(&delayed_rsv->lock); 656 657 spin_lock(&delayed_refs_rsv->lock); 658 reclaim_bytes += delayed_refs_rsv->reserved; 659 spin_unlock(&delayed_refs_rsv->lock); 660 661 spin_lock(&trans_rsv->lock); 662 reclaim_bytes += trans_rsv->reserved; 663 spin_unlock(&trans_rsv->lock); 664 665 if (reclaim_bytes >= bytes_needed) 666 goto commit; 667 bytes_needed -= reclaim_bytes; 668 669 if (__percpu_counter_compare(&space_info->total_bytes_pinned, 670 bytes_needed, 671 BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0) 672 goto enospc; 673 674 commit: 675 return btrfs_commit_transaction(trans); 676 enospc: 677 btrfs_end_transaction(trans); 678 return -ENOSPC; 679 } 680 681 /* 682 * Try to flush some data based on policy set by @state. This is only advisory 683 * and may fail for various reasons. The caller is supposed to examine the 684 * state of @space_info to detect the outcome. 685 */ 686 static void flush_space(struct btrfs_fs_info *fs_info, 687 struct btrfs_space_info *space_info, u64 num_bytes, 688 enum btrfs_flush_state state, bool for_preempt) 689 { 690 struct btrfs_root *root = fs_info->extent_root; 691 struct btrfs_trans_handle *trans; 692 int nr; 693 int ret = 0; 694 695 switch (state) { 696 case FLUSH_DELAYED_ITEMS_NR: 697 case FLUSH_DELAYED_ITEMS: 698 if (state == FLUSH_DELAYED_ITEMS_NR) 699 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2; 700 else 701 nr = -1; 702 703 trans = btrfs_join_transaction(root); 704 if (IS_ERR(trans)) { 705 ret = PTR_ERR(trans); 706 break; 707 } 708 ret = btrfs_run_delayed_items_nr(trans, nr); 709 btrfs_end_transaction(trans); 710 break; 711 case FLUSH_DELALLOC: 712 case FLUSH_DELALLOC_WAIT: 713 shrink_delalloc(fs_info, space_info, num_bytes, 714 state == FLUSH_DELALLOC_WAIT, for_preempt); 715 break; 716 case FLUSH_DELAYED_REFS_NR: 717 case FLUSH_DELAYED_REFS: 718 trans = btrfs_join_transaction(root); 719 if (IS_ERR(trans)) { 720 ret = PTR_ERR(trans); 721 break; 722 } 723 if (state == FLUSH_DELAYED_REFS_NR) 724 nr = calc_reclaim_items_nr(fs_info, num_bytes); 725 else 726 nr = 0; 727 btrfs_run_delayed_refs(trans, nr); 728 btrfs_end_transaction(trans); 729 break; 730 case ALLOC_CHUNK: 731 case ALLOC_CHUNK_FORCE: 732 trans = btrfs_join_transaction(root); 733 if (IS_ERR(trans)) { 734 ret = PTR_ERR(trans); 735 break; 736 } 737 ret = btrfs_chunk_alloc(trans, 738 btrfs_get_alloc_profile(fs_info, space_info->flags), 739 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE : 740 CHUNK_ALLOC_FORCE); 741 btrfs_end_transaction(trans); 742 if (ret > 0 || ret == -ENOSPC) 743 ret = 0; 744 break; 745 case RUN_DELAYED_IPUTS: 746 /* 747 * If we have pending delayed iputs then we could free up a 748 * bunch of pinned space, so make sure we run the iputs before 749 * we do our pinned bytes check below. 750 */ 751 btrfs_run_delayed_iputs(fs_info); 752 btrfs_wait_on_delayed_iputs(fs_info); 753 break; 754 case COMMIT_TRANS: 755 ret = may_commit_transaction(fs_info, space_info); 756 break; 757 case FORCE_COMMIT_TRANS: 758 trans = btrfs_join_transaction(root); 759 if (IS_ERR(trans)) { 760 ret = PTR_ERR(trans); 761 break; 762 } 763 ret = btrfs_commit_transaction(trans); 764 break; 765 default: 766 ret = -ENOSPC; 767 break; 768 } 769 770 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state, 771 ret, for_preempt); 772 return; 773 } 774 775 static inline u64 776 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info, 777 struct btrfs_space_info *space_info) 778 { 779 u64 used; 780 u64 avail; 781 u64 to_reclaim = space_info->reclaim_size; 782 783 lockdep_assert_held(&space_info->lock); 784 785 avail = calc_available_free_space(fs_info, space_info, 786 BTRFS_RESERVE_FLUSH_ALL); 787 used = btrfs_space_info_used(space_info, true); 788 789 /* 790 * We may be flushing because suddenly we have less space than we had 791 * before, and now we're well over-committed based on our current free 792 * space. If that's the case add in our overage so we make sure to put 793 * appropriate pressure on the flushing state machine. 794 */ 795 if (space_info->total_bytes + avail < used) 796 to_reclaim += used - (space_info->total_bytes + avail); 797 798 return to_reclaim; 799 } 800 801 static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info, 802 struct btrfs_space_info *space_info) 803 { 804 u64 global_rsv_size = fs_info->global_block_rsv.reserved; 805 u64 ordered, delalloc; 806 u64 thresh = div_factor_fine(space_info->total_bytes, 98); 807 u64 used; 808 809 /* If we're just plain full then async reclaim just slows us down. */ 810 if ((space_info->bytes_used + space_info->bytes_reserved + 811 global_rsv_size) >= thresh) 812 return false; 813 814 /* 815 * We have tickets queued, bail so we don't compete with the async 816 * flushers. 817 */ 818 if (space_info->reclaim_size) 819 return false; 820 821 /* 822 * If we have over half of the free space occupied by reservations or 823 * pinned then we want to start flushing. 824 * 825 * We do not do the traditional thing here, which is to say 826 * 827 * if (used >= ((total_bytes + avail) / 2)) 828 * return 1; 829 * 830 * because this doesn't quite work how we want. If we had more than 50% 831 * of the space_info used by bytes_used and we had 0 available we'd just 832 * constantly run the background flusher. Instead we want it to kick in 833 * if our reclaimable space exceeds our clamped free space. 834 * 835 * Our clamping range is 2^1 -> 2^8. Practically speaking that means 836 * the following: 837 * 838 * Amount of RAM Minimum threshold Maximum threshold 839 * 840 * 256GiB 1GiB 128GiB 841 * 128GiB 512MiB 64GiB 842 * 64GiB 256MiB 32GiB 843 * 32GiB 128MiB 16GiB 844 * 16GiB 64MiB 8GiB 845 * 846 * These are the range our thresholds will fall in, corresponding to how 847 * much delalloc we need for the background flusher to kick in. 848 */ 849 850 thresh = calc_available_free_space(fs_info, space_info, 851 BTRFS_RESERVE_FLUSH_ALL); 852 used = space_info->bytes_used + space_info->bytes_reserved + 853 space_info->bytes_readonly + global_rsv_size; 854 if (used < space_info->total_bytes) 855 thresh += space_info->total_bytes - used; 856 thresh >>= space_info->clamp; 857 858 used = space_info->bytes_pinned; 859 860 /* 861 * If we have more ordered bytes than delalloc bytes then we're either 862 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting 863 * around. Preemptive flushing is only useful in that it can free up 864 * space before tickets need to wait for things to finish. In the case 865 * of ordered extents, preemptively waiting on ordered extents gets us 866 * nothing, if our reservations are tied up in ordered extents we'll 867 * simply have to slow down writers by forcing them to wait on ordered 868 * extents. 869 * 870 * In the case that ordered is larger than delalloc, only include the 871 * block reserves that we would actually be able to directly reclaim 872 * from. In this case if we're heavy on metadata operations this will 873 * clearly be heavy enough to warrant preemptive flushing. In the case 874 * of heavy DIO or ordered reservations, preemptive flushing will just 875 * waste time and cause us to slow down. 876 * 877 * We want to make sure we truly are maxed out on ordered however, so 878 * cut ordered in half, and if it's still higher than delalloc then we 879 * can keep flushing. This is to avoid the case where we start 880 * flushing, and now delalloc == ordered and we stop preemptively 881 * flushing when we could still have several gigs of delalloc to flush. 882 */ 883 ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1; 884 delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes); 885 if (ordered >= delalloc) 886 used += fs_info->delayed_refs_rsv.reserved + 887 fs_info->delayed_block_rsv.reserved; 888 else 889 used += space_info->bytes_may_use - global_rsv_size; 890 891 return (used >= thresh && !btrfs_fs_closing(fs_info) && 892 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state)); 893 } 894 895 static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info, 896 struct btrfs_space_info *space_info, 897 struct reserve_ticket *ticket) 898 { 899 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv; 900 u64 min_bytes; 901 902 if (global_rsv->space_info != space_info) 903 return false; 904 905 spin_lock(&global_rsv->lock); 906 min_bytes = div_factor(global_rsv->size, 1); 907 if (global_rsv->reserved < min_bytes + ticket->bytes) { 908 spin_unlock(&global_rsv->lock); 909 return false; 910 } 911 global_rsv->reserved -= ticket->bytes; 912 remove_ticket(space_info, ticket); 913 ticket->bytes = 0; 914 wake_up(&ticket->wait); 915 space_info->tickets_id++; 916 if (global_rsv->reserved < global_rsv->size) 917 global_rsv->full = 0; 918 spin_unlock(&global_rsv->lock); 919 920 return true; 921 } 922 923 /* 924 * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets 925 * @fs_info - fs_info for this fs 926 * @space_info - the space info we were flushing 927 * 928 * We call this when we've exhausted our flushing ability and haven't made 929 * progress in satisfying tickets. The reservation code handles tickets in 930 * order, so if there is a large ticket first and then smaller ones we could 931 * very well satisfy the smaller tickets. This will attempt to wake up any 932 * tickets in the list to catch this case. 933 * 934 * This function returns true if it was able to make progress by clearing out 935 * other tickets, or if it stumbles across a ticket that was smaller than the 936 * first ticket. 937 */ 938 static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info, 939 struct btrfs_space_info *space_info) 940 { 941 struct reserve_ticket *ticket; 942 u64 tickets_id = space_info->tickets_id; 943 u64 first_ticket_bytes = 0; 944 945 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) { 946 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info"); 947 __btrfs_dump_space_info(fs_info, space_info); 948 } 949 950 while (!list_empty(&space_info->tickets) && 951 tickets_id == space_info->tickets_id) { 952 ticket = list_first_entry(&space_info->tickets, 953 struct reserve_ticket, list); 954 955 if (ticket->steal && 956 steal_from_global_rsv(fs_info, space_info, ticket)) 957 return true; 958 959 /* 960 * may_commit_transaction will avoid committing the transaction 961 * if it doesn't feel like the space reclaimed by the commit 962 * would result in the ticket succeeding. However if we have a 963 * smaller ticket in the queue it may be small enough to be 964 * satisfied by committing the transaction, so if any 965 * subsequent ticket is smaller than the first ticket go ahead 966 * and send us back for another loop through the enospc flushing 967 * code. 968 */ 969 if (first_ticket_bytes == 0) 970 first_ticket_bytes = ticket->bytes; 971 else if (first_ticket_bytes > ticket->bytes) 972 return true; 973 974 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 975 btrfs_info(fs_info, "failing ticket with %llu bytes", 976 ticket->bytes); 977 978 remove_ticket(space_info, ticket); 979 ticket->error = -ENOSPC; 980 wake_up(&ticket->wait); 981 982 /* 983 * We're just throwing tickets away, so more flushing may not 984 * trip over btrfs_try_granting_tickets, so we need to call it 985 * here to see if we can make progress with the next ticket in 986 * the list. 987 */ 988 btrfs_try_granting_tickets(fs_info, space_info); 989 } 990 return (tickets_id != space_info->tickets_id); 991 } 992 993 /* 994 * This is for normal flushers, we can wait all goddamned day if we want to. We 995 * will loop and continuously try to flush as long as we are making progress. 996 * We count progress as clearing off tickets each time we have to loop. 997 */ 998 static void btrfs_async_reclaim_metadata_space(struct work_struct *work) 999 { 1000 struct btrfs_fs_info *fs_info; 1001 struct btrfs_space_info *space_info; 1002 u64 to_reclaim; 1003 enum btrfs_flush_state flush_state; 1004 int commit_cycles = 0; 1005 u64 last_tickets_id; 1006 1007 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work); 1008 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); 1009 1010 spin_lock(&space_info->lock); 1011 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); 1012 if (!to_reclaim) { 1013 space_info->flush = 0; 1014 spin_unlock(&space_info->lock); 1015 return; 1016 } 1017 last_tickets_id = space_info->tickets_id; 1018 spin_unlock(&space_info->lock); 1019 1020 flush_state = FLUSH_DELAYED_ITEMS_NR; 1021 do { 1022 flush_space(fs_info, space_info, to_reclaim, flush_state, false); 1023 spin_lock(&space_info->lock); 1024 if (list_empty(&space_info->tickets)) { 1025 space_info->flush = 0; 1026 spin_unlock(&space_info->lock); 1027 return; 1028 } 1029 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, 1030 space_info); 1031 if (last_tickets_id == space_info->tickets_id) { 1032 flush_state++; 1033 } else { 1034 last_tickets_id = space_info->tickets_id; 1035 flush_state = FLUSH_DELAYED_ITEMS_NR; 1036 if (commit_cycles) 1037 commit_cycles--; 1038 } 1039 1040 /* 1041 * We don't want to force a chunk allocation until we've tried 1042 * pretty hard to reclaim space. Think of the case where we 1043 * freed up a bunch of space and so have a lot of pinned space 1044 * to reclaim. We would rather use that than possibly create a 1045 * underutilized metadata chunk. So if this is our first run 1046 * through the flushing state machine skip ALLOC_CHUNK_FORCE and 1047 * commit the transaction. If nothing has changed the next go 1048 * around then we can force a chunk allocation. 1049 */ 1050 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles) 1051 flush_state++; 1052 1053 if (flush_state > COMMIT_TRANS) { 1054 commit_cycles++; 1055 if (commit_cycles > 2) { 1056 if (maybe_fail_all_tickets(fs_info, space_info)) { 1057 flush_state = FLUSH_DELAYED_ITEMS_NR; 1058 commit_cycles--; 1059 } else { 1060 space_info->flush = 0; 1061 } 1062 } else { 1063 flush_state = FLUSH_DELAYED_ITEMS_NR; 1064 } 1065 } 1066 spin_unlock(&space_info->lock); 1067 } while (flush_state <= COMMIT_TRANS); 1068 } 1069 1070 /* 1071 * This handles pre-flushing of metadata space before we get to the point that 1072 * we need to start blocking threads on tickets. The logic here is different 1073 * from the other flush paths because it doesn't rely on tickets to tell us how 1074 * much we need to flush, instead it attempts to keep us below the 80% full 1075 * watermark of space by flushing whichever reservation pool is currently the 1076 * largest. 1077 */ 1078 static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work) 1079 { 1080 struct btrfs_fs_info *fs_info; 1081 struct btrfs_space_info *space_info; 1082 struct btrfs_block_rsv *delayed_block_rsv; 1083 struct btrfs_block_rsv *delayed_refs_rsv; 1084 struct btrfs_block_rsv *global_rsv; 1085 struct btrfs_block_rsv *trans_rsv; 1086 int loops = 0; 1087 1088 fs_info = container_of(work, struct btrfs_fs_info, 1089 preempt_reclaim_work); 1090 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); 1091 delayed_block_rsv = &fs_info->delayed_block_rsv; 1092 delayed_refs_rsv = &fs_info->delayed_refs_rsv; 1093 global_rsv = &fs_info->global_block_rsv; 1094 trans_rsv = &fs_info->trans_block_rsv; 1095 1096 spin_lock(&space_info->lock); 1097 while (need_preemptive_reclaim(fs_info, space_info)) { 1098 enum btrfs_flush_state flush; 1099 u64 delalloc_size = 0; 1100 u64 to_reclaim, block_rsv_size; 1101 u64 global_rsv_size = global_rsv->reserved; 1102 1103 loops++; 1104 1105 /* 1106 * We don't have a precise counter for the metadata being 1107 * reserved for delalloc, so we'll approximate it by subtracting 1108 * out the block rsv's space from the bytes_may_use. If that 1109 * amount is higher than the individual reserves, then we can 1110 * assume it's tied up in delalloc reservations. 1111 */ 1112 block_rsv_size = global_rsv_size + 1113 delayed_block_rsv->reserved + 1114 delayed_refs_rsv->reserved + 1115 trans_rsv->reserved; 1116 if (block_rsv_size < space_info->bytes_may_use) 1117 delalloc_size = space_info->bytes_may_use - block_rsv_size; 1118 spin_unlock(&space_info->lock); 1119 1120 /* 1121 * We don't want to include the global_rsv in our calculation, 1122 * because that's space we can't touch. Subtract it from the 1123 * block_rsv_size for the next checks. 1124 */ 1125 block_rsv_size -= global_rsv_size; 1126 1127 /* 1128 * We really want to avoid flushing delalloc too much, as it 1129 * could result in poor allocation patterns, so only flush it if 1130 * it's larger than the rest of the pools combined. 1131 */ 1132 if (delalloc_size > block_rsv_size) { 1133 to_reclaim = delalloc_size; 1134 flush = FLUSH_DELALLOC; 1135 } else if (space_info->bytes_pinned > 1136 (delayed_block_rsv->reserved + 1137 delayed_refs_rsv->reserved)) { 1138 to_reclaim = space_info->bytes_pinned; 1139 flush = FORCE_COMMIT_TRANS; 1140 } else if (delayed_block_rsv->reserved > 1141 delayed_refs_rsv->reserved) { 1142 to_reclaim = delayed_block_rsv->reserved; 1143 flush = FLUSH_DELAYED_ITEMS_NR; 1144 } else { 1145 to_reclaim = delayed_refs_rsv->reserved; 1146 flush = FLUSH_DELAYED_REFS_NR; 1147 } 1148 1149 /* 1150 * We don't want to reclaim everything, just a portion, so scale 1151 * down the to_reclaim by 1/4. If it takes us down to 0, 1152 * reclaim 1 items worth. 1153 */ 1154 to_reclaim >>= 2; 1155 if (!to_reclaim) 1156 to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1); 1157 flush_space(fs_info, space_info, to_reclaim, flush, true); 1158 cond_resched(); 1159 spin_lock(&space_info->lock); 1160 } 1161 1162 /* We only went through once, back off our clamping. */ 1163 if (loops == 1 && !space_info->reclaim_size) 1164 space_info->clamp = max(1, space_info->clamp - 1); 1165 trace_btrfs_done_preemptive_reclaim(fs_info, space_info); 1166 spin_unlock(&space_info->lock); 1167 } 1168 1169 /* 1170 * FLUSH_DELALLOC_WAIT: 1171 * Space is freed from flushing delalloc in one of two ways. 1172 * 1173 * 1) compression is on and we allocate less space than we reserved 1174 * 2) we are overwriting existing space 1175 * 1176 * For #1 that extra space is reclaimed as soon as the delalloc pages are 1177 * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent 1178 * length to ->bytes_reserved, and subtracts the reserved space from 1179 * ->bytes_may_use. 1180 * 1181 * For #2 this is trickier. Once the ordered extent runs we will drop the 1182 * extent in the range we are overwriting, which creates a delayed ref for 1183 * that freed extent. This however is not reclaimed until the transaction 1184 * commits, thus the next stages. 1185 * 1186 * RUN_DELAYED_IPUTS 1187 * If we are freeing inodes, we want to make sure all delayed iputs have 1188 * completed, because they could have been on an inode with i_nlink == 0, and 1189 * thus have been truncated and freed up space. But again this space is not 1190 * immediately re-usable, it comes in the form of a delayed ref, which must be 1191 * run and then the transaction must be committed. 1192 * 1193 * FLUSH_DELAYED_REFS 1194 * The above two cases generate delayed refs that will affect 1195 * ->total_bytes_pinned. However this counter can be inconsistent with 1196 * reality if there are outstanding delayed refs. This is because we adjust 1197 * the counter based solely on the current set of delayed refs and disregard 1198 * any on-disk state which might include more refs. So for example, if we 1199 * have an extent with 2 references, but we only drop 1, we'll see that there 1200 * is a negative delayed ref count for the extent and assume that the space 1201 * will be freed, and thus increase ->total_bytes_pinned. 1202 * 1203 * Running the delayed refs gives us the actual real view of what will be 1204 * freed at the transaction commit time. This stage will not actually free 1205 * space for us, it just makes sure that may_commit_transaction() has all of 1206 * the information it needs to make the right decision. 1207 * 1208 * COMMIT_TRANS 1209 * This is where we reclaim all of the pinned space generated by the previous 1210 * two stages. We will not commit the transaction if we don't think we're 1211 * likely to satisfy our request, which means if our current free space + 1212 * total_bytes_pinned < reservation we will not commit. This is why the 1213 * previous states are actually important, to make sure we know for sure 1214 * whether committing the transaction will allow us to make progress. 1215 * 1216 * ALLOC_CHUNK_FORCE 1217 * For data we start with alloc chunk force, however we could have been full 1218 * before, and then the transaction commit could have freed new block groups, 1219 * so if we now have space to allocate do the force chunk allocation. 1220 */ 1221 static const enum btrfs_flush_state data_flush_states[] = { 1222 FLUSH_DELALLOC_WAIT, 1223 RUN_DELAYED_IPUTS, 1224 FLUSH_DELAYED_REFS, 1225 COMMIT_TRANS, 1226 ALLOC_CHUNK_FORCE, 1227 }; 1228 1229 static void btrfs_async_reclaim_data_space(struct work_struct *work) 1230 { 1231 struct btrfs_fs_info *fs_info; 1232 struct btrfs_space_info *space_info; 1233 u64 last_tickets_id; 1234 enum btrfs_flush_state flush_state = 0; 1235 1236 fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work); 1237 space_info = fs_info->data_sinfo; 1238 1239 spin_lock(&space_info->lock); 1240 if (list_empty(&space_info->tickets)) { 1241 space_info->flush = 0; 1242 spin_unlock(&space_info->lock); 1243 return; 1244 } 1245 last_tickets_id = space_info->tickets_id; 1246 spin_unlock(&space_info->lock); 1247 1248 while (!space_info->full) { 1249 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); 1250 spin_lock(&space_info->lock); 1251 if (list_empty(&space_info->tickets)) { 1252 space_info->flush = 0; 1253 spin_unlock(&space_info->lock); 1254 return; 1255 } 1256 last_tickets_id = space_info->tickets_id; 1257 spin_unlock(&space_info->lock); 1258 } 1259 1260 while (flush_state < ARRAY_SIZE(data_flush_states)) { 1261 flush_space(fs_info, space_info, U64_MAX, 1262 data_flush_states[flush_state], false); 1263 spin_lock(&space_info->lock); 1264 if (list_empty(&space_info->tickets)) { 1265 space_info->flush = 0; 1266 spin_unlock(&space_info->lock); 1267 return; 1268 } 1269 1270 if (last_tickets_id == space_info->tickets_id) { 1271 flush_state++; 1272 } else { 1273 last_tickets_id = space_info->tickets_id; 1274 flush_state = 0; 1275 } 1276 1277 if (flush_state >= ARRAY_SIZE(data_flush_states)) { 1278 if (space_info->full) { 1279 if (maybe_fail_all_tickets(fs_info, space_info)) 1280 flush_state = 0; 1281 else 1282 space_info->flush = 0; 1283 } else { 1284 flush_state = 0; 1285 } 1286 } 1287 spin_unlock(&space_info->lock); 1288 } 1289 } 1290 1291 void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info) 1292 { 1293 INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space); 1294 INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space); 1295 INIT_WORK(&fs_info->preempt_reclaim_work, 1296 btrfs_preempt_reclaim_metadata_space); 1297 } 1298 1299 static const enum btrfs_flush_state priority_flush_states[] = { 1300 FLUSH_DELAYED_ITEMS_NR, 1301 FLUSH_DELAYED_ITEMS, 1302 ALLOC_CHUNK, 1303 }; 1304 1305 static const enum btrfs_flush_state evict_flush_states[] = { 1306 FLUSH_DELAYED_ITEMS_NR, 1307 FLUSH_DELAYED_ITEMS, 1308 FLUSH_DELAYED_REFS_NR, 1309 FLUSH_DELAYED_REFS, 1310 FLUSH_DELALLOC, 1311 FLUSH_DELALLOC_WAIT, 1312 ALLOC_CHUNK, 1313 COMMIT_TRANS, 1314 }; 1315 1316 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info, 1317 struct btrfs_space_info *space_info, 1318 struct reserve_ticket *ticket, 1319 const enum btrfs_flush_state *states, 1320 int states_nr) 1321 { 1322 u64 to_reclaim; 1323 int flush_state; 1324 1325 spin_lock(&space_info->lock); 1326 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); 1327 if (!to_reclaim) { 1328 spin_unlock(&space_info->lock); 1329 return; 1330 } 1331 spin_unlock(&space_info->lock); 1332 1333 flush_state = 0; 1334 do { 1335 flush_space(fs_info, space_info, to_reclaim, states[flush_state], 1336 false); 1337 flush_state++; 1338 spin_lock(&space_info->lock); 1339 if (ticket->bytes == 0) { 1340 spin_unlock(&space_info->lock); 1341 return; 1342 } 1343 spin_unlock(&space_info->lock); 1344 } while (flush_state < states_nr); 1345 } 1346 1347 static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info, 1348 struct btrfs_space_info *space_info, 1349 struct reserve_ticket *ticket) 1350 { 1351 while (!space_info->full) { 1352 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); 1353 spin_lock(&space_info->lock); 1354 if (ticket->bytes == 0) { 1355 spin_unlock(&space_info->lock); 1356 return; 1357 } 1358 spin_unlock(&space_info->lock); 1359 } 1360 } 1361 1362 static void wait_reserve_ticket(struct btrfs_fs_info *fs_info, 1363 struct btrfs_space_info *space_info, 1364 struct reserve_ticket *ticket) 1365 1366 { 1367 DEFINE_WAIT(wait); 1368 int ret = 0; 1369 1370 spin_lock(&space_info->lock); 1371 while (ticket->bytes > 0 && ticket->error == 0) { 1372 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE); 1373 if (ret) { 1374 /* 1375 * Delete us from the list. After we unlock the space 1376 * info, we don't want the async reclaim job to reserve 1377 * space for this ticket. If that would happen, then the 1378 * ticket's task would not known that space was reserved 1379 * despite getting an error, resulting in a space leak 1380 * (bytes_may_use counter of our space_info). 1381 */ 1382 remove_ticket(space_info, ticket); 1383 ticket->error = -EINTR; 1384 break; 1385 } 1386 spin_unlock(&space_info->lock); 1387 1388 schedule(); 1389 1390 finish_wait(&ticket->wait, &wait); 1391 spin_lock(&space_info->lock); 1392 } 1393 spin_unlock(&space_info->lock); 1394 } 1395 1396 /** 1397 * Do the appropriate flushing and waiting for a ticket 1398 * 1399 * @fs_info: the filesystem 1400 * @space_info: space info for the reservation 1401 * @ticket: ticket for the reservation 1402 * @start_ns: timestamp when the reservation started 1403 * @orig_bytes: amount of bytes originally reserved 1404 * @flush: how much we can flush 1405 * 1406 * This does the work of figuring out how to flush for the ticket, waiting for 1407 * the reservation, and returning the appropriate error if there is one. 1408 */ 1409 static int handle_reserve_ticket(struct btrfs_fs_info *fs_info, 1410 struct btrfs_space_info *space_info, 1411 struct reserve_ticket *ticket, 1412 u64 start_ns, u64 orig_bytes, 1413 enum btrfs_reserve_flush_enum flush) 1414 { 1415 int ret; 1416 1417 switch (flush) { 1418 case BTRFS_RESERVE_FLUSH_DATA: 1419 case BTRFS_RESERVE_FLUSH_ALL: 1420 case BTRFS_RESERVE_FLUSH_ALL_STEAL: 1421 wait_reserve_ticket(fs_info, space_info, ticket); 1422 break; 1423 case BTRFS_RESERVE_FLUSH_LIMIT: 1424 priority_reclaim_metadata_space(fs_info, space_info, ticket, 1425 priority_flush_states, 1426 ARRAY_SIZE(priority_flush_states)); 1427 break; 1428 case BTRFS_RESERVE_FLUSH_EVICT: 1429 priority_reclaim_metadata_space(fs_info, space_info, ticket, 1430 evict_flush_states, 1431 ARRAY_SIZE(evict_flush_states)); 1432 break; 1433 case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE: 1434 priority_reclaim_data_space(fs_info, space_info, ticket); 1435 break; 1436 default: 1437 ASSERT(0); 1438 break; 1439 } 1440 1441 spin_lock(&space_info->lock); 1442 ret = ticket->error; 1443 if (ticket->bytes || ticket->error) { 1444 /* 1445 * We were a priority ticket, so we need to delete ourselves 1446 * from the list. Because we could have other priority tickets 1447 * behind us that require less space, run 1448 * btrfs_try_granting_tickets() to see if their reservations can 1449 * now be made. 1450 */ 1451 if (!list_empty(&ticket->list)) { 1452 remove_ticket(space_info, ticket); 1453 btrfs_try_granting_tickets(fs_info, space_info); 1454 } 1455 1456 if (!ret) 1457 ret = -ENOSPC; 1458 } 1459 spin_unlock(&space_info->lock); 1460 ASSERT(list_empty(&ticket->list)); 1461 /* 1462 * Check that we can't have an error set if the reservation succeeded, 1463 * as that would confuse tasks and lead them to error out without 1464 * releasing reserved space (if an error happens the expectation is that 1465 * space wasn't reserved at all). 1466 */ 1467 ASSERT(!(ticket->bytes == 0 && ticket->error)); 1468 trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes, 1469 start_ns, flush, ticket->error); 1470 return ret; 1471 } 1472 1473 /* 1474 * This returns true if this flush state will go through the ordinary flushing 1475 * code. 1476 */ 1477 static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush) 1478 { 1479 return (flush == BTRFS_RESERVE_FLUSH_ALL) || 1480 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); 1481 } 1482 1483 static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info, 1484 struct btrfs_space_info *space_info) 1485 { 1486 u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes); 1487 u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes); 1488 1489 /* 1490 * If we're heavy on ordered operations then clamping won't help us. We 1491 * need to clamp specifically to keep up with dirty'ing buffered 1492 * writers, because there's not a 1:1 correlation of writing delalloc 1493 * and freeing space, like there is with flushing delayed refs or 1494 * delayed nodes. If we're already more ordered than delalloc then 1495 * we're keeping up, otherwise we aren't and should probably clamp. 1496 */ 1497 if (ordered < delalloc) 1498 space_info->clamp = min(space_info->clamp + 1, 8); 1499 } 1500 1501 /** 1502 * Try to reserve bytes from the block_rsv's space 1503 * 1504 * @fs_info: the filesystem 1505 * @space_info: space info we want to allocate from 1506 * @orig_bytes: number of bytes we want 1507 * @flush: whether or not we can flush to make our reservation 1508 * 1509 * This will reserve orig_bytes number of bytes from the space info associated 1510 * with the block_rsv. If there is not enough space it will make an attempt to 1511 * flush out space to make room. It will do this by flushing delalloc if 1512 * possible or committing the transaction. If flush is 0 then no attempts to 1513 * regain reservations will be made and this will fail if there is not enough 1514 * space already. 1515 */ 1516 static int __reserve_bytes(struct btrfs_fs_info *fs_info, 1517 struct btrfs_space_info *space_info, u64 orig_bytes, 1518 enum btrfs_reserve_flush_enum flush) 1519 { 1520 struct work_struct *async_work; 1521 struct reserve_ticket ticket; 1522 u64 start_ns = 0; 1523 u64 used; 1524 int ret = 0; 1525 bool pending_tickets; 1526 1527 ASSERT(orig_bytes); 1528 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL); 1529 1530 if (flush == BTRFS_RESERVE_FLUSH_DATA) 1531 async_work = &fs_info->async_data_reclaim_work; 1532 else 1533 async_work = &fs_info->async_reclaim_work; 1534 1535 spin_lock(&space_info->lock); 1536 ret = -ENOSPC; 1537 used = btrfs_space_info_used(space_info, true); 1538 1539 /* 1540 * We don't want NO_FLUSH allocations to jump everybody, they can 1541 * generally handle ENOSPC in a different way, so treat them the same as 1542 * normal flushers when it comes to skipping pending tickets. 1543 */ 1544 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH)) 1545 pending_tickets = !list_empty(&space_info->tickets) || 1546 !list_empty(&space_info->priority_tickets); 1547 else 1548 pending_tickets = !list_empty(&space_info->priority_tickets); 1549 1550 /* 1551 * Carry on if we have enough space (short-circuit) OR call 1552 * can_overcommit() to ensure we can overcommit to continue. 1553 */ 1554 if (!pending_tickets && 1555 ((used + orig_bytes <= space_info->total_bytes) || 1556 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) { 1557 btrfs_space_info_update_bytes_may_use(fs_info, space_info, 1558 orig_bytes); 1559 ret = 0; 1560 } 1561 1562 /* 1563 * If we couldn't make a reservation then setup our reservation ticket 1564 * and kick the async worker if it's not already running. 1565 * 1566 * If we are a priority flusher then we just need to add our ticket to 1567 * the list and we will do our own flushing further down. 1568 */ 1569 if (ret && flush != BTRFS_RESERVE_NO_FLUSH) { 1570 ticket.bytes = orig_bytes; 1571 ticket.error = 0; 1572 space_info->reclaim_size += ticket.bytes; 1573 init_waitqueue_head(&ticket.wait); 1574 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); 1575 if (trace_btrfs_reserve_ticket_enabled()) 1576 start_ns = ktime_get_ns(); 1577 1578 if (flush == BTRFS_RESERVE_FLUSH_ALL || 1579 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL || 1580 flush == BTRFS_RESERVE_FLUSH_DATA) { 1581 list_add_tail(&ticket.list, &space_info->tickets); 1582 if (!space_info->flush) { 1583 /* 1584 * We were forced to add a reserve ticket, so 1585 * our preemptive flushing is unable to keep 1586 * up. Clamp down on the threshold for the 1587 * preemptive flushing in order to keep up with 1588 * the workload. 1589 */ 1590 maybe_clamp_preempt(fs_info, space_info); 1591 1592 space_info->flush = 1; 1593 trace_btrfs_trigger_flush(fs_info, 1594 space_info->flags, 1595 orig_bytes, flush, 1596 "enospc"); 1597 queue_work(system_unbound_wq, async_work); 1598 } 1599 } else { 1600 list_add_tail(&ticket.list, 1601 &space_info->priority_tickets); 1602 } 1603 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) { 1604 used += orig_bytes; 1605 /* 1606 * We will do the space reservation dance during log replay, 1607 * which means we won't have fs_info->fs_root set, so don't do 1608 * the async reclaim as we will panic. 1609 */ 1610 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) && 1611 !work_busy(&fs_info->preempt_reclaim_work) && 1612 need_preemptive_reclaim(fs_info, space_info)) { 1613 trace_btrfs_trigger_flush(fs_info, space_info->flags, 1614 orig_bytes, flush, "preempt"); 1615 queue_work(system_unbound_wq, 1616 &fs_info->preempt_reclaim_work); 1617 } 1618 } 1619 spin_unlock(&space_info->lock); 1620 if (!ret || flush == BTRFS_RESERVE_NO_FLUSH) 1621 return ret; 1622 1623 return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns, 1624 orig_bytes, flush); 1625 } 1626 1627 /** 1628 * Trye to reserve metadata bytes from the block_rsv's space 1629 * 1630 * @root: the root we're allocating for 1631 * @block_rsv: block_rsv we're allocating for 1632 * @orig_bytes: number of bytes we want 1633 * @flush: whether or not we can flush to make our reservation 1634 * 1635 * This will reserve orig_bytes number of bytes from the space info associated 1636 * with the block_rsv. If there is not enough space it will make an attempt to 1637 * flush out space to make room. It will do this by flushing delalloc if 1638 * possible or committing the transaction. If flush is 0 then no attempts to 1639 * regain reservations will be made and this will fail if there is not enough 1640 * space already. 1641 */ 1642 int btrfs_reserve_metadata_bytes(struct btrfs_root *root, 1643 struct btrfs_block_rsv *block_rsv, 1644 u64 orig_bytes, 1645 enum btrfs_reserve_flush_enum flush) 1646 { 1647 struct btrfs_fs_info *fs_info = root->fs_info; 1648 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv; 1649 int ret; 1650 1651 ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush); 1652 if (ret == -ENOSPC && 1653 unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) { 1654 if (block_rsv != global_rsv && 1655 !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes)) 1656 ret = 0; 1657 } 1658 if (ret == -ENOSPC) { 1659 trace_btrfs_space_reservation(fs_info, "space_info:enospc", 1660 block_rsv->space_info->flags, 1661 orig_bytes, 1); 1662 1663 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 1664 btrfs_dump_space_info(fs_info, block_rsv->space_info, 1665 orig_bytes, 0); 1666 } 1667 return ret; 1668 } 1669 1670 /** 1671 * Try to reserve data bytes for an allocation 1672 * 1673 * @fs_info: the filesystem 1674 * @bytes: number of bytes we need 1675 * @flush: how we are allowed to flush 1676 * 1677 * This will reserve bytes from the data space info. If there is not enough 1678 * space then we will attempt to flush space as specified by flush. 1679 */ 1680 int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes, 1681 enum btrfs_reserve_flush_enum flush) 1682 { 1683 struct btrfs_space_info *data_sinfo = fs_info->data_sinfo; 1684 int ret; 1685 1686 ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA || 1687 flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE); 1688 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA); 1689 1690 ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush); 1691 if (ret == -ENOSPC) { 1692 trace_btrfs_space_reservation(fs_info, "space_info:enospc", 1693 data_sinfo->flags, bytes, 1); 1694 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) 1695 btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0); 1696 } 1697 return ret; 1698 } 1699