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