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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 * OVERCOMMIT
144 *
145 * Because we hold so many reservations for metadata we will allow you to
146 * reserve more space than is currently free in the currently allocate
147 * metadata space. This only happens with metadata, data does not allow
148 * overcommitting.
149 *
150 * You can see the current logic for when we allow overcommit in
151 * btrfs_can_overcommit(), but it only applies to unallocated space. If there
152 * is no unallocated space to be had, all reservations are kept within the
153 * free space in the allocated metadata chunks.
154 *
155 * Because of overcommitting, you generally want to use the
156 * btrfs_can_overcommit() logic for metadata allocations, as it does the right
157 * thing with or without extra unallocated space.
158 */
159
160u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
161 bool may_use_included)
162{
163 ASSERT(s_info);
164 return s_info->bytes_used + s_info->bytes_reserved +
165 s_info->bytes_pinned + s_info->bytes_readonly +
166 (may_use_included ? s_info->bytes_may_use : 0);
167}
168
169/*
170 * after adding space to the filesystem, we need to clear the full flags
171 * on all the space infos.
172 */
173void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
174{
175 struct list_head *head = &info->space_info;
176 struct btrfs_space_info *found;
177
178 rcu_read_lock();
179 list_for_each_entry_rcu(found, head, list)
180 found->full = 0;
181 rcu_read_unlock();
182}
183
184static int create_space_info(struct btrfs_fs_info *info, u64 flags)
185{
186
187 struct btrfs_space_info *space_info;
188 int i;
189 int ret;
190
191 space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
192 if (!space_info)
193 return -ENOMEM;
194
195 ret = percpu_counter_init(&space_info->total_bytes_pinned, 0,
196 GFP_KERNEL);
197 if (ret) {
198 kfree(space_info);
199 return ret;
200 }
201
202 for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
203 INIT_LIST_HEAD(&space_info->block_groups[i]);
204 init_rwsem(&space_info->groups_sem);
205 spin_lock_init(&space_info->lock);
206 space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
207 space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
208 INIT_LIST_HEAD(&space_info->ro_bgs);
209 INIT_LIST_HEAD(&space_info->tickets);
210 INIT_LIST_HEAD(&space_info->priority_tickets);
211
212 ret = btrfs_sysfs_add_space_info_type(info, space_info);
213 if (ret)
214 return ret;
215
216 list_add_rcu(&space_info->list, &info->space_info);
217 if (flags & BTRFS_BLOCK_GROUP_DATA)
218 info->data_sinfo = space_info;
219
220 return ret;
221}
222
223int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
224{
225 struct btrfs_super_block *disk_super;
226 u64 features;
227 u64 flags;
228 int mixed = 0;
229 int ret;
230
231 disk_super = fs_info->super_copy;
232 if (!btrfs_super_root(disk_super))
233 return -EINVAL;
234
235 features = btrfs_super_incompat_flags(disk_super);
236 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
237 mixed = 1;
238
239 flags = BTRFS_BLOCK_GROUP_SYSTEM;
240 ret = create_space_info(fs_info, flags);
241 if (ret)
242 goto out;
243
244 if (mixed) {
245 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
246 ret = create_space_info(fs_info, flags);
247 } else {
248 flags = BTRFS_BLOCK_GROUP_METADATA;
249 ret = create_space_info(fs_info, flags);
250 if (ret)
251 goto out;
252
253 flags = BTRFS_BLOCK_GROUP_DATA;
254 ret = create_space_info(fs_info, flags);
255 }
256out:
257 return ret;
258}
259
260void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
261 u64 total_bytes, u64 bytes_used,
262 u64 bytes_readonly,
263 struct btrfs_space_info **space_info)
264{
265 struct btrfs_space_info *found;
266 int factor;
267
268 factor = btrfs_bg_type_to_factor(flags);
269
270 found = btrfs_find_space_info(info, flags);
271 ASSERT(found);
272 spin_lock(&found->lock);
273 found->total_bytes += total_bytes;
274 found->disk_total += total_bytes * factor;
275 found->bytes_used += bytes_used;
276 found->disk_used += bytes_used * factor;
277 found->bytes_readonly += bytes_readonly;
278 if (total_bytes > 0)
279 found->full = 0;
280 btrfs_try_granting_tickets(info, found);
281 spin_unlock(&found->lock);
282 *space_info = found;
283}
284
285struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
286 u64 flags)
287{
288 struct list_head *head = &info->space_info;
289 struct btrfs_space_info *found;
290
291 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
292
293 rcu_read_lock();
294 list_for_each_entry_rcu(found, head, list) {
295 if (found->flags & flags) {
296 rcu_read_unlock();
297 return found;
298 }
299 }
300 rcu_read_unlock();
301 return NULL;
302}
303
304static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
305{
306 return (global->size << 1);
307}
308
309static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
310 struct btrfs_space_info *space_info,
311 enum btrfs_reserve_flush_enum flush)
312{
313 u64 profile;
314 u64 avail;
315 int factor;
316
317 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
318 profile = btrfs_system_alloc_profile(fs_info);
319 else
320 profile = btrfs_metadata_alloc_profile(fs_info);
321
322 avail = atomic64_read(&fs_info->free_chunk_space);
323
324 /*
325 * If we have dup, raid1 or raid10 then only half of the free
326 * space is actually usable. For raid56, the space info used
327 * doesn't include the parity drive, so we don't have to
328 * change the math
329 */
330 factor = btrfs_bg_type_to_factor(profile);
331 avail = div_u64(avail, factor);
332
333 /*
334 * If we aren't flushing all things, let us overcommit up to
335 * 1/2th of the space. If we can flush, don't let us overcommit
336 * too much, let it overcommit up to 1/8 of the space.
337 */
338 if (flush == BTRFS_RESERVE_FLUSH_ALL)
339 avail >>= 3;
340 else
341 avail >>= 1;
342 return avail;
343}
344
345int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
346 struct btrfs_space_info *space_info, u64 bytes,
347 enum btrfs_reserve_flush_enum flush)
348{
349 u64 avail;
350 u64 used;
351
352 /* Don't overcommit when in mixed mode */
353 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
354 return 0;
355
356 used = btrfs_space_info_used(space_info, true);
357 avail = calc_available_free_space(fs_info, space_info, flush);
358
359 if (used + bytes < space_info->total_bytes + avail)
360 return 1;
361 return 0;
362}
363
364static void remove_ticket(struct btrfs_space_info *space_info,
365 struct reserve_ticket *ticket)
366{
367 if (!list_empty(&ticket->list)) {
368 list_del_init(&ticket->list);
369 ASSERT(space_info->reclaim_size >= ticket->bytes);
370 space_info->reclaim_size -= ticket->bytes;
371 }
372}
373
374/*
375 * This is for space we already have accounted in space_info->bytes_may_use, so
376 * basically when we're returning space from block_rsv's.
377 */
378void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
379 struct btrfs_space_info *space_info)
380{
381 struct list_head *head;
382 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
383
384 lockdep_assert_held(&space_info->lock);
385
386 head = &space_info->priority_tickets;
387again:
388 while (!list_empty(head)) {
389 struct reserve_ticket *ticket;
390 u64 used = btrfs_space_info_used(space_info, true);
391
392 ticket = list_first_entry(head, struct reserve_ticket, list);
393
394 /* Check and see if our ticket can be satisified now. */
395 if ((used + ticket->bytes <= space_info->total_bytes) ||
396 btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
397 flush)) {
398 btrfs_space_info_update_bytes_may_use(fs_info,
399 space_info,
400 ticket->bytes);
401 remove_ticket(space_info, ticket);
402 ticket->bytes = 0;
403 space_info->tickets_id++;
404 wake_up(&ticket->wait);
405 } else {
406 break;
407 }
408 }
409
410 if (head == &space_info->priority_tickets) {
411 head = &space_info->tickets;
412 flush = BTRFS_RESERVE_FLUSH_ALL;
413 goto again;
414 }
415}
416
417#define DUMP_BLOCK_RSV(fs_info, rsv_name) \
418do { \
419 struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \
420 spin_lock(&__rsv->lock); \
421 btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \
422 __rsv->size, __rsv->reserved); \
423 spin_unlock(&__rsv->lock); \
424} while (0)
425
426static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
427 struct btrfs_space_info *info)
428{
429 lockdep_assert_held(&info->lock);
430
431 btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
432 info->flags,
433 info->total_bytes - btrfs_space_info_used(info, true),
434 info->full ? "" : "not ");
435 btrfs_info(fs_info,
436 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu",
437 info->total_bytes, info->bytes_used, info->bytes_pinned,
438 info->bytes_reserved, info->bytes_may_use,
439 info->bytes_readonly);
440
441 DUMP_BLOCK_RSV(fs_info, global_block_rsv);
442 DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
443 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
444 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
445 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
446
447}
448
449void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
450 struct btrfs_space_info *info, u64 bytes,
451 int dump_block_groups)
452{
453 struct btrfs_block_group *cache;
454 int index = 0;
455
456 spin_lock(&info->lock);
457 __btrfs_dump_space_info(fs_info, info);
458 spin_unlock(&info->lock);
459
460 if (!dump_block_groups)
461 return;
462
463 down_read(&info->groups_sem);
464again:
465 list_for_each_entry(cache, &info->block_groups[index], list) {
466 spin_lock(&cache->lock);
467 btrfs_info(fs_info,
468 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %s",
469 cache->start, cache->length, cache->used, cache->pinned,
470 cache->reserved, cache->ro ? "[readonly]" : "");
471 spin_unlock(&cache->lock);
472 btrfs_dump_free_space(cache, bytes);
473 }
474 if (++index < BTRFS_NR_RAID_TYPES)
475 goto again;
476 up_read(&info->groups_sem);
477}
478
479static void btrfs_writeback_inodes_sb_nr(struct btrfs_fs_info *fs_info,
480 unsigned long nr_pages, int nr_items)
481{
482 struct super_block *sb = fs_info->sb;
483
484 if (down_read_trylock(&sb->s_umount)) {
485 writeback_inodes_sb_nr(sb, nr_pages, WB_REASON_FS_FREE_SPACE);
486 up_read(&sb->s_umount);
487 } else {
488 /*
489 * We needn't worry the filesystem going from r/w to r/o though
490 * we don't acquire ->s_umount mutex, because the filesystem
491 * should guarantee the delalloc inodes list be empty after
492 * the filesystem is readonly(all dirty pages are written to
493 * the disk).
494 */
495 btrfs_start_delalloc_roots(fs_info, nr_items);
496 if (!current->journal_info)
497 btrfs_wait_ordered_roots(fs_info, nr_items, 0, (u64)-1);
498 }
499}
500
501static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
502 u64 to_reclaim)
503{
504 u64 bytes;
505 u64 nr;
506
507 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
508 nr = div64_u64(to_reclaim, bytes);
509 if (!nr)
510 nr = 1;
511 return nr;
512}
513
514#define EXTENT_SIZE_PER_ITEM SZ_256K
515
516/*
517 * shrink metadata reservation for delalloc
518 */
519static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
520 u64 orig, bool wait_ordered)
521{
522 struct btrfs_space_info *space_info;
523 struct btrfs_trans_handle *trans;
524 u64 delalloc_bytes;
525 u64 dio_bytes;
526 u64 async_pages;
527 u64 items;
528 long time_left;
529 unsigned long nr_pages;
530 int loops;
531
532 /* Calc the number of the pages we need flush for space reservation */
533 items = calc_reclaim_items_nr(fs_info, to_reclaim);
534 to_reclaim = items * EXTENT_SIZE_PER_ITEM;
535
536 trans = (struct btrfs_trans_handle *)current->journal_info;
537 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
538
539 delalloc_bytes = percpu_counter_sum_positive(
540 &fs_info->delalloc_bytes);
541 dio_bytes = percpu_counter_sum_positive(&fs_info->dio_bytes);
542 if (delalloc_bytes == 0 && dio_bytes == 0) {
543 if (trans)
544 return;
545 if (wait_ordered)
546 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
547 return;
548 }
549
550 /*
551 * If we are doing more ordered than delalloc we need to just wait on
552 * ordered extents, otherwise we'll waste time trying to flush delalloc
553 * that likely won't give us the space back we need.
554 */
555 if (dio_bytes > delalloc_bytes)
556 wait_ordered = true;
557
558 loops = 0;
559 while ((delalloc_bytes || dio_bytes) && loops < 3) {
560 nr_pages = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
561
562 /*
563 * Triggers inode writeback for up to nr_pages. This will invoke
564 * ->writepages callback and trigger delalloc filling
565 * (btrfs_run_delalloc_range()).
566 */
567 btrfs_writeback_inodes_sb_nr(fs_info, nr_pages, items);
568
569 /*
570 * We need to wait for the compressed pages to start before
571 * we continue.
572 */
573 async_pages = atomic_read(&fs_info->async_delalloc_pages);
574 if (!async_pages)
575 goto skip_async;
576
577 /*
578 * Calculate how many compressed pages we want to be written
579 * before we continue. I.e if there are more async pages than we
580 * require wait_event will wait until nr_pages are written.
581 */
582 if (async_pages <= nr_pages)
583 async_pages = 0;
584 else
585 async_pages -= nr_pages;
586
587 wait_event(fs_info->async_submit_wait,
588 atomic_read(&fs_info->async_delalloc_pages) <=
589 (int)async_pages);
590skip_async:
591 spin_lock(&space_info->lock);
592 if (list_empty(&space_info->tickets) &&
593 list_empty(&space_info->priority_tickets)) {
594 spin_unlock(&space_info->lock);
595 break;
596 }
597 spin_unlock(&space_info->lock);
598
599 loops++;
600 if (wait_ordered && !trans) {
601 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
602 } else {
603 time_left = schedule_timeout_killable(1);
604 if (time_left)
605 break;
606 }
607 delalloc_bytes = percpu_counter_sum_positive(
608 &fs_info->delalloc_bytes);
609 dio_bytes = percpu_counter_sum_positive(&fs_info->dio_bytes);
610 }
611}
612
613/**
614 * maybe_commit_transaction - possibly commit the transaction if its ok to
615 * @root - the root we're allocating for
616 * @bytes - the number of bytes we want to reserve
617 * @force - force the commit
618 *
619 * This will check to make sure that committing the transaction will actually
620 * get us somewhere and then commit the transaction if it does. Otherwise it
621 * will return -ENOSPC.
622 */
623static int may_commit_transaction(struct btrfs_fs_info *fs_info,
624 struct btrfs_space_info *space_info)
625{
626 struct reserve_ticket *ticket = NULL;
627 struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv;
628 struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
629 struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
630 struct btrfs_trans_handle *trans;
631 u64 bytes_needed;
632 u64 reclaim_bytes = 0;
633 u64 cur_free_bytes = 0;
634
635 trans = (struct btrfs_trans_handle *)current->journal_info;
636 if (trans)
637 return -EAGAIN;
638
639 spin_lock(&space_info->lock);
640 cur_free_bytes = btrfs_space_info_used(space_info, true);
641 if (cur_free_bytes < space_info->total_bytes)
642 cur_free_bytes = space_info->total_bytes - cur_free_bytes;
643 else
644 cur_free_bytes = 0;
645
646 if (!list_empty(&space_info->priority_tickets))
647 ticket = list_first_entry(&space_info->priority_tickets,
648 struct reserve_ticket, list);
649 else if (!list_empty(&space_info->tickets))
650 ticket = list_first_entry(&space_info->tickets,
651 struct reserve_ticket, list);
652 bytes_needed = (ticket) ? ticket->bytes : 0;
653
654 if (bytes_needed > cur_free_bytes)
655 bytes_needed -= cur_free_bytes;
656 else
657 bytes_needed = 0;
658 spin_unlock(&space_info->lock);
659
660 if (!bytes_needed)
661 return 0;
662
663 trans = btrfs_join_transaction(fs_info->extent_root);
664 if (IS_ERR(trans))
665 return PTR_ERR(trans);
666
667 /*
668 * See if there is enough pinned space to make this reservation, or if
669 * we have block groups that are going to be freed, allowing us to
670 * possibly do a chunk allocation the next loop through.
671 */
672 if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags) ||
673 __percpu_counter_compare(&space_info->total_bytes_pinned,
674 bytes_needed,
675 BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0)
676 goto commit;
677
678 /*
679 * See if there is some space in the delayed insertion reservation for
680 * this reservation.
681 */
682 if (space_info != delayed_rsv->space_info)
683 goto enospc;
684
685 spin_lock(&delayed_rsv->lock);
686 reclaim_bytes += delayed_rsv->reserved;
687 spin_unlock(&delayed_rsv->lock);
688
689 spin_lock(&delayed_refs_rsv->lock);
690 reclaim_bytes += delayed_refs_rsv->reserved;
691 spin_unlock(&delayed_refs_rsv->lock);
692
693 spin_lock(&trans_rsv->lock);
694 reclaim_bytes += trans_rsv->reserved;
695 spin_unlock(&trans_rsv->lock);
696
697 if (reclaim_bytes >= bytes_needed)
698 goto commit;
699 bytes_needed -= reclaim_bytes;
700
701 if (__percpu_counter_compare(&space_info->total_bytes_pinned,
702 bytes_needed,
703 BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0)
704 goto enospc;
705
706commit:
707 return btrfs_commit_transaction(trans);
708enospc:
709 btrfs_end_transaction(trans);
710 return -ENOSPC;
711}
712
713/*
714 * Try to flush some data based on policy set by @state. This is only advisory
715 * and may fail for various reasons. The caller is supposed to examine the
716 * state of @space_info to detect the outcome.
717 */
718static void flush_space(struct btrfs_fs_info *fs_info,
719 struct btrfs_space_info *space_info, u64 num_bytes,
720 int state)
721{
722 struct btrfs_root *root = fs_info->extent_root;
723 struct btrfs_trans_handle *trans;
724 int nr;
725 int ret = 0;
726
727 switch (state) {
728 case FLUSH_DELAYED_ITEMS_NR:
729 case FLUSH_DELAYED_ITEMS:
730 if (state == FLUSH_DELAYED_ITEMS_NR)
731 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
732 else
733 nr = -1;
734
735 trans = btrfs_join_transaction(root);
736 if (IS_ERR(trans)) {
737 ret = PTR_ERR(trans);
738 break;
739 }
740 ret = btrfs_run_delayed_items_nr(trans, nr);
741 btrfs_end_transaction(trans);
742 break;
743 case FLUSH_DELALLOC:
744 case FLUSH_DELALLOC_WAIT:
745 shrink_delalloc(fs_info, num_bytes * 2, num_bytes,
746 state == FLUSH_DELALLOC_WAIT);
747 break;
748 case FLUSH_DELAYED_REFS_NR:
749 case FLUSH_DELAYED_REFS:
750 trans = btrfs_join_transaction(root);
751 if (IS_ERR(trans)) {
752 ret = PTR_ERR(trans);
753 break;
754 }
755 if (state == FLUSH_DELAYED_REFS_NR)
756 nr = calc_reclaim_items_nr(fs_info, num_bytes);
757 else
758 nr = 0;
759 btrfs_run_delayed_refs(trans, nr);
760 btrfs_end_transaction(trans);
761 break;
762 case ALLOC_CHUNK:
763 case ALLOC_CHUNK_FORCE:
764 trans = btrfs_join_transaction(root);
765 if (IS_ERR(trans)) {
766 ret = PTR_ERR(trans);
767 break;
768 }
769 ret = btrfs_chunk_alloc(trans,
770 btrfs_metadata_alloc_profile(fs_info),
771 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
772 CHUNK_ALLOC_FORCE);
773 btrfs_end_transaction(trans);
774 if (ret > 0 || ret == -ENOSPC)
775 ret = 0;
776 break;
777 case RUN_DELAYED_IPUTS:
778 /*
779 * If we have pending delayed iputs then we could free up a
780 * bunch of pinned space, so make sure we run the iputs before
781 * we do our pinned bytes check below.
782 */
783 btrfs_run_delayed_iputs(fs_info);
784 btrfs_wait_on_delayed_iputs(fs_info);
785 break;
786 case COMMIT_TRANS:
787 ret = may_commit_transaction(fs_info, space_info);
788 break;
789 default:
790 ret = -ENOSPC;
791 break;
792 }
793
794 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
795 ret);
796 return;
797}
798
799static inline u64
800btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
801 struct btrfs_space_info *space_info)
802{
803 u64 used;
804 u64 avail;
805 u64 expected;
806 u64 to_reclaim = space_info->reclaim_size;
807
808 lockdep_assert_held(&space_info->lock);
809
810 avail = calc_available_free_space(fs_info, space_info,
811 BTRFS_RESERVE_FLUSH_ALL);
812 used = btrfs_space_info_used(space_info, true);
813
814 /*
815 * We may be flushing because suddenly we have less space than we had
816 * before, and now we're well over-committed based on our current free
817 * space. If that's the case add in our overage so we make sure to put
818 * appropriate pressure on the flushing state machine.
819 */
820 if (space_info->total_bytes + avail < used)
821 to_reclaim += used - (space_info->total_bytes + avail);
822
823 if (to_reclaim)
824 return to_reclaim;
825
826 to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
827 if (btrfs_can_overcommit(fs_info, space_info, to_reclaim,
828 BTRFS_RESERVE_FLUSH_ALL))
829 return 0;
830
831 used = btrfs_space_info_used(space_info, true);
832
833 if (btrfs_can_overcommit(fs_info, space_info, SZ_1M,
834 BTRFS_RESERVE_FLUSH_ALL))
835 expected = div_factor_fine(space_info->total_bytes, 95);
836 else
837 expected = div_factor_fine(space_info->total_bytes, 90);
838
839 if (used > expected)
840 to_reclaim = used - expected;
841 else
842 to_reclaim = 0;
843 to_reclaim = min(to_reclaim, space_info->bytes_may_use +
844 space_info->bytes_reserved);
845 return to_reclaim;
846}
847
848static inline int need_do_async_reclaim(struct btrfs_fs_info *fs_info,
849 struct btrfs_space_info *space_info,
850 u64 used)
851{
852 u64 thresh = div_factor_fine(space_info->total_bytes, 98);
853
854 /* If we're just plain full then async reclaim just slows us down. */
855 if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
856 return 0;
857
858 if (!btrfs_calc_reclaim_metadata_size(fs_info, space_info))
859 return 0;
860
861 return (used >= thresh && !btrfs_fs_closing(fs_info) &&
862 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
863}
864
865static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
866 struct btrfs_space_info *space_info,
867 struct reserve_ticket *ticket)
868{
869 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
870 u64 min_bytes;
871
872 if (global_rsv->space_info != space_info)
873 return false;
874
875 spin_lock(&global_rsv->lock);
876 min_bytes = div_factor(global_rsv->size, 1);
877 if (global_rsv->reserved < min_bytes + ticket->bytes) {
878 spin_unlock(&global_rsv->lock);
879 return false;
880 }
881 global_rsv->reserved -= ticket->bytes;
882 remove_ticket(space_info, ticket);
883 ticket->bytes = 0;
884 wake_up(&ticket->wait);
885 space_info->tickets_id++;
886 if (global_rsv->reserved < global_rsv->size)
887 global_rsv->full = 0;
888 spin_unlock(&global_rsv->lock);
889
890 return true;
891}
892
893/*
894 * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets
895 * @fs_info - fs_info for this fs
896 * @space_info - the space info we were flushing
897 *
898 * We call this when we've exhausted our flushing ability and haven't made
899 * progress in satisfying tickets. The reservation code handles tickets in
900 * order, so if there is a large ticket first and then smaller ones we could
901 * very well satisfy the smaller tickets. This will attempt to wake up any
902 * tickets in the list to catch this case.
903 *
904 * This function returns true if it was able to make progress by clearing out
905 * other tickets, or if it stumbles across a ticket that was smaller than the
906 * first ticket.
907 */
908static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
909 struct btrfs_space_info *space_info)
910{
911 struct reserve_ticket *ticket;
912 u64 tickets_id = space_info->tickets_id;
913 u64 first_ticket_bytes = 0;
914
915 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
916 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
917 __btrfs_dump_space_info(fs_info, space_info);
918 }
919
920 while (!list_empty(&space_info->tickets) &&
921 tickets_id == space_info->tickets_id) {
922 ticket = list_first_entry(&space_info->tickets,
923 struct reserve_ticket, list);
924
925 if (ticket->steal &&
926 steal_from_global_rsv(fs_info, space_info, ticket))
927 return true;
928
929 /*
930 * may_commit_transaction will avoid committing the transaction
931 * if it doesn't feel like the space reclaimed by the commit
932 * would result in the ticket succeeding. However if we have a
933 * smaller ticket in the queue it may be small enough to be
934 * satisified by committing the transaction, so if any
935 * subsequent ticket is smaller than the first ticket go ahead
936 * and send us back for another loop through the enospc flushing
937 * code.
938 */
939 if (first_ticket_bytes == 0)
940 first_ticket_bytes = ticket->bytes;
941 else if (first_ticket_bytes > ticket->bytes)
942 return true;
943
944 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
945 btrfs_info(fs_info, "failing ticket with %llu bytes",
946 ticket->bytes);
947
948 remove_ticket(space_info, ticket);
949 ticket->error = -ENOSPC;
950 wake_up(&ticket->wait);
951
952 /*
953 * We're just throwing tickets away, so more flushing may not
954 * trip over btrfs_try_granting_tickets, so we need to call it
955 * here to see if we can make progress with the next ticket in
956 * the list.
957 */
958 btrfs_try_granting_tickets(fs_info, space_info);
959 }
960 return (tickets_id != space_info->tickets_id);
961}
962
963/*
964 * This is for normal flushers, we can wait all goddamned day if we want to. We
965 * will loop and continuously try to flush as long as we are making progress.
966 * We count progress as clearing off tickets each time we have to loop.
967 */
968static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
969{
970 struct btrfs_fs_info *fs_info;
971 struct btrfs_space_info *space_info;
972 u64 to_reclaim;
973 int flush_state;
974 int commit_cycles = 0;
975 u64 last_tickets_id;
976
977 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
978 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
979
980 spin_lock(&space_info->lock);
981 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
982 if (!to_reclaim) {
983 space_info->flush = 0;
984 spin_unlock(&space_info->lock);
985 return;
986 }
987 last_tickets_id = space_info->tickets_id;
988 spin_unlock(&space_info->lock);
989
990 flush_state = FLUSH_DELAYED_ITEMS_NR;
991 do {
992 flush_space(fs_info, space_info, to_reclaim, flush_state);
993 spin_lock(&space_info->lock);
994 if (list_empty(&space_info->tickets)) {
995 space_info->flush = 0;
996 spin_unlock(&space_info->lock);
997 return;
998 }
999 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1000 space_info);
1001 if (last_tickets_id == space_info->tickets_id) {
1002 flush_state++;
1003 } else {
1004 last_tickets_id = space_info->tickets_id;
1005 flush_state = FLUSH_DELAYED_ITEMS_NR;
1006 if (commit_cycles)
1007 commit_cycles--;
1008 }
1009
1010 /*
1011 * We don't want to force a chunk allocation until we've tried
1012 * pretty hard to reclaim space. Think of the case where we
1013 * freed up a bunch of space and so have a lot of pinned space
1014 * to reclaim. We would rather use that than possibly create a
1015 * underutilized metadata chunk. So if this is our first run
1016 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1017 * commit the transaction. If nothing has changed the next go
1018 * around then we can force a chunk allocation.
1019 */
1020 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1021 flush_state++;
1022
1023 if (flush_state > COMMIT_TRANS) {
1024 commit_cycles++;
1025 if (commit_cycles > 2) {
1026 if (maybe_fail_all_tickets(fs_info, space_info)) {
1027 flush_state = FLUSH_DELAYED_ITEMS_NR;
1028 commit_cycles--;
1029 } else {
1030 space_info->flush = 0;
1031 }
1032 } else {
1033 flush_state = FLUSH_DELAYED_ITEMS_NR;
1034 }
1035 }
1036 spin_unlock(&space_info->lock);
1037 } while (flush_state <= COMMIT_TRANS);
1038}
1039
1040void btrfs_init_async_reclaim_work(struct work_struct *work)
1041{
1042 INIT_WORK(work, btrfs_async_reclaim_metadata_space);
1043}
1044
1045static const enum btrfs_flush_state priority_flush_states[] = {
1046 FLUSH_DELAYED_ITEMS_NR,
1047 FLUSH_DELAYED_ITEMS,
1048 ALLOC_CHUNK,
1049};
1050
1051static const enum btrfs_flush_state evict_flush_states[] = {
1052 FLUSH_DELAYED_ITEMS_NR,
1053 FLUSH_DELAYED_ITEMS,
1054 FLUSH_DELAYED_REFS_NR,
1055 FLUSH_DELAYED_REFS,
1056 FLUSH_DELALLOC,
1057 FLUSH_DELALLOC_WAIT,
1058 ALLOC_CHUNK,
1059 COMMIT_TRANS,
1060};
1061
1062static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1063 struct btrfs_space_info *space_info,
1064 struct reserve_ticket *ticket,
1065 const enum btrfs_flush_state *states,
1066 int states_nr)
1067{
1068 u64 to_reclaim;
1069 int flush_state;
1070
1071 spin_lock(&space_info->lock);
1072 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1073 if (!to_reclaim) {
1074 spin_unlock(&space_info->lock);
1075 return;
1076 }
1077 spin_unlock(&space_info->lock);
1078
1079 flush_state = 0;
1080 do {
1081 flush_space(fs_info, space_info, to_reclaim, states[flush_state]);
1082 flush_state++;
1083 spin_lock(&space_info->lock);
1084 if (ticket->bytes == 0) {
1085 spin_unlock(&space_info->lock);
1086 return;
1087 }
1088 spin_unlock(&space_info->lock);
1089 } while (flush_state < states_nr);
1090}
1091
1092static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1093 struct btrfs_space_info *space_info,
1094 struct reserve_ticket *ticket)
1095
1096{
1097 DEFINE_WAIT(wait);
1098 int ret = 0;
1099
1100 spin_lock(&space_info->lock);
1101 while (ticket->bytes > 0 && ticket->error == 0) {
1102 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1103 if (ret) {
1104 /*
1105 * Delete us from the list. After we unlock the space
1106 * info, we don't want the async reclaim job to reserve
1107 * space for this ticket. If that would happen, then the
1108 * ticket's task would not known that space was reserved
1109 * despite getting an error, resulting in a space leak
1110 * (bytes_may_use counter of our space_info).
1111 */
1112 remove_ticket(space_info, ticket);
1113 ticket->error = -EINTR;
1114 break;
1115 }
1116 spin_unlock(&space_info->lock);
1117
1118 schedule();
1119
1120 finish_wait(&ticket->wait, &wait);
1121 spin_lock(&space_info->lock);
1122 }
1123 spin_unlock(&space_info->lock);
1124}
1125
1126/**
1127 * handle_reserve_ticket - do the appropriate flushing and waiting for a ticket
1128 * @fs_info - the fs
1129 * @space_info - the space_info for the reservation
1130 * @ticket - the ticket for the reservation
1131 * @flush - how much we can flush
1132 *
1133 * This does the work of figuring out how to flush for the ticket, waiting for
1134 * the reservation, and returning the appropriate error if there is one.
1135 */
1136static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1137 struct btrfs_space_info *space_info,
1138 struct reserve_ticket *ticket,
1139 enum btrfs_reserve_flush_enum flush)
1140{
1141 int ret;
1142
1143 switch (flush) {
1144 case BTRFS_RESERVE_FLUSH_ALL:
1145 case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1146 wait_reserve_ticket(fs_info, space_info, ticket);
1147 break;
1148 case BTRFS_RESERVE_FLUSH_LIMIT:
1149 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1150 priority_flush_states,
1151 ARRAY_SIZE(priority_flush_states));
1152 break;
1153 case BTRFS_RESERVE_FLUSH_EVICT:
1154 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1155 evict_flush_states,
1156 ARRAY_SIZE(evict_flush_states));
1157 break;
1158 default:
1159 ASSERT(0);
1160 break;
1161 }
1162
1163 spin_lock(&space_info->lock);
1164 ret = ticket->error;
1165 if (ticket->bytes || ticket->error) {
1166 /*
1167 * We were a priority ticket, so we need to delete ourselves
1168 * from the list. Because we could have other priority tickets
1169 * behind us that require less space, run
1170 * btrfs_try_granting_tickets() to see if their reservations can
1171 * now be made.
1172 */
1173 if (!list_empty(&ticket->list)) {
1174 remove_ticket(space_info, ticket);
1175 btrfs_try_granting_tickets(fs_info, space_info);
1176 }
1177
1178 if (!ret)
1179 ret = -ENOSPC;
1180 }
1181 spin_unlock(&space_info->lock);
1182 ASSERT(list_empty(&ticket->list));
1183 /*
1184 * Check that we can't have an error set if the reservation succeeded,
1185 * as that would confuse tasks and lead them to error out without
1186 * releasing reserved space (if an error happens the expectation is that
1187 * space wasn't reserved at all).
1188 */
1189 ASSERT(!(ticket->bytes == 0 && ticket->error));
1190 return ret;
1191}
1192
1193/*
1194 * This returns true if this flush state will go through the ordinary flushing
1195 * code.
1196 */
1197static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1198{
1199 return (flush == BTRFS_RESERVE_FLUSH_ALL) ||
1200 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1201}
1202
1203/**
1204 * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
1205 * @root - the root we're allocating for
1206 * @space_info - the space info we want to allocate from
1207 * @orig_bytes - the number of bytes we want
1208 * @flush - whether or not we can flush to make our reservation
1209 *
1210 * This will reserve orig_bytes number of bytes from the space info associated
1211 * with the block_rsv. If there is not enough space it will make an attempt to
1212 * flush out space to make room. It will do this by flushing delalloc if
1213 * possible or committing the transaction. If flush is 0 then no attempts to
1214 * regain reservations will be made and this will fail if there is not enough
1215 * space already.
1216 */
1217static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1218 struct btrfs_space_info *space_info,
1219 u64 orig_bytes,
1220 enum btrfs_reserve_flush_enum flush)
1221{
1222 struct reserve_ticket ticket;
1223 u64 used;
1224 int ret = 0;
1225 bool pending_tickets;
1226
1227 ASSERT(orig_bytes);
1228 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
1229
1230 spin_lock(&space_info->lock);
1231 ret = -ENOSPC;
1232 used = btrfs_space_info_used(space_info, true);
1233
1234 /*
1235 * We don't want NO_FLUSH allocations to jump everybody, they can
1236 * generally handle ENOSPC in a different way, so treat them the same as
1237 * normal flushers when it comes to skipping pending tickets.
1238 */
1239 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1240 pending_tickets = !list_empty(&space_info->tickets) ||
1241 !list_empty(&space_info->priority_tickets);
1242 else
1243 pending_tickets = !list_empty(&space_info->priority_tickets);
1244
1245 /*
1246 * Carry on if we have enough space (short-circuit) OR call
1247 * can_overcommit() to ensure we can overcommit to continue.
1248 */
1249 if (!pending_tickets &&
1250 ((used + orig_bytes <= space_info->total_bytes) ||
1251 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1252 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1253 orig_bytes);
1254 ret = 0;
1255 }
1256
1257 /*
1258 * If we couldn't make a reservation then setup our reservation ticket
1259 * and kick the async worker if it's not already running.
1260 *
1261 * If we are a priority flusher then we just need to add our ticket to
1262 * the list and we will do our own flushing further down.
1263 */
1264 if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
1265 ticket.bytes = orig_bytes;
1266 ticket.error = 0;
1267 space_info->reclaim_size += ticket.bytes;
1268 init_waitqueue_head(&ticket.wait);
1269 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1270 if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1271 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {
1272 list_add_tail(&ticket.list, &space_info->tickets);
1273 if (!space_info->flush) {
1274 space_info->flush = 1;
1275 trace_btrfs_trigger_flush(fs_info,
1276 space_info->flags,
1277 orig_bytes, flush,
1278 "enospc");
1279 queue_work(system_unbound_wq,
1280 &fs_info->async_reclaim_work);
1281 }
1282 } else {
1283 list_add_tail(&ticket.list,
1284 &space_info->priority_tickets);
1285 }
1286 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1287 used += orig_bytes;
1288 /*
1289 * We will do the space reservation dance during log replay,
1290 * which means we won't have fs_info->fs_root set, so don't do
1291 * the async reclaim as we will panic.
1292 */
1293 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1294 need_do_async_reclaim(fs_info, space_info, used) &&
1295 !work_busy(&fs_info->async_reclaim_work)) {
1296 trace_btrfs_trigger_flush(fs_info, space_info->flags,
1297 orig_bytes, flush, "preempt");
1298 queue_work(system_unbound_wq,
1299 &fs_info->async_reclaim_work);
1300 }
1301 }
1302 spin_unlock(&space_info->lock);
1303 if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
1304 return ret;
1305
1306 return handle_reserve_ticket(fs_info, space_info, &ticket, flush);
1307}
1308
1309/**
1310 * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
1311 * @root - the root we're allocating for
1312 * @block_rsv - the block_rsv we're allocating for
1313 * @orig_bytes - the number of bytes we want
1314 * @flush - whether or not we can flush to make our reservation
1315 *
1316 * This will reserve orig_bytes number of bytes from the space info associated
1317 * with the block_rsv. If there is not enough space it will make an attempt to
1318 * flush out space to make room. It will do this by flushing delalloc if
1319 * possible or committing the transaction. If flush is 0 then no attempts to
1320 * regain reservations will be made and this will fail if there is not enough
1321 * space already.
1322 */
1323int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
1324 struct btrfs_block_rsv *block_rsv,
1325 u64 orig_bytes,
1326 enum btrfs_reserve_flush_enum flush)
1327{
1328 struct btrfs_fs_info *fs_info = root->fs_info;
1329 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
1330 int ret;
1331
1332 ret = __reserve_metadata_bytes(fs_info, block_rsv->space_info,
1333 orig_bytes, flush);
1334 if (ret == -ENOSPC &&
1335 unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
1336 if (block_rsv != global_rsv &&
1337 !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes))
1338 ret = 0;
1339 }
1340 if (ret == -ENOSPC) {
1341 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1342 block_rsv->space_info->flags,
1343 orig_bytes, 1);
1344
1345 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1346 btrfs_dump_space_info(fs_info, block_rsv->space_info,
1347 orig_bytes, 0);
1348 }
1349 return ret;
1350}
1// SPDX-License-Identifier: GPL-2.0
2
3#include "linux/spinlock.h"
4#include <linux/minmax.h>
5#include "misc.h"
6#include "ctree.h"
7#include "space-info.h"
8#include "sysfs.h"
9#include "volumes.h"
10#include "free-space-cache.h"
11#include "ordered-data.h"
12#include "transaction.h"
13#include "block-group.h"
14#include "fs.h"
15#include "accessors.h"
16#include "extent-tree.h"
17
18/*
19 * HOW DOES SPACE RESERVATION WORK
20 *
21 * If you want to know about delalloc specifically, there is a separate comment
22 * for that with the delalloc code. This comment is about how the whole system
23 * works generally.
24 *
25 * BASIC CONCEPTS
26 *
27 * 1) space_info. This is the ultimate arbiter of how much space we can use.
28 * There's a description of the bytes_ fields with the struct declaration,
29 * refer to that for specifics on each field. Suffice it to say that for
30 * reservations we care about total_bytes - SUM(space_info->bytes_) when
31 * determining if there is space to make an allocation. There is a space_info
32 * for METADATA, SYSTEM, and DATA areas.
33 *
34 * 2) block_rsv's. These are basically buckets for every different type of
35 * metadata reservation we have. You can see the comment in the block_rsv
36 * code on the rules for each type, but generally block_rsv->reserved is how
37 * much space is accounted for in space_info->bytes_may_use.
38 *
39 * 3) btrfs_calc*_size. These are the worst case calculations we used based
40 * on the number of items we will want to modify. We have one for changing
41 * items, and one for inserting new items. Generally we use these helpers to
42 * determine the size of the block reserves, and then use the actual bytes
43 * values to adjust the space_info counters.
44 *
45 * MAKING RESERVATIONS, THE NORMAL CASE
46 *
47 * We call into either btrfs_reserve_data_bytes() or
48 * btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
49 * num_bytes we want to reserve.
50 *
51 * ->reserve
52 * space_info->bytes_may_reserve += num_bytes
53 *
54 * ->extent allocation
55 * Call btrfs_add_reserved_bytes() which does
56 * space_info->bytes_may_reserve -= num_bytes
57 * space_info->bytes_reserved += extent_bytes
58 *
59 * ->insert reference
60 * Call btrfs_update_block_group() which does
61 * space_info->bytes_reserved -= extent_bytes
62 * space_info->bytes_used += extent_bytes
63 *
64 * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
65 *
66 * Assume we are unable to simply make the reservation because we do not have
67 * enough space
68 *
69 * -> __reserve_bytes
70 * create a reserve_ticket with ->bytes set to our reservation, add it to
71 * the tail of space_info->tickets, kick async flush thread
72 *
73 * ->handle_reserve_ticket
74 * wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
75 * on the ticket.
76 *
77 * -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
78 * Flushes various things attempting to free up space.
79 *
80 * -> btrfs_try_granting_tickets()
81 * This is called by anything that either subtracts space from
82 * space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
83 * space_info->total_bytes. This loops through the ->priority_tickets and
84 * then the ->tickets list checking to see if the reservation can be
85 * completed. If it can the space is added to space_info->bytes_may_use and
86 * the ticket is woken up.
87 *
88 * -> ticket wakeup
89 * Check if ->bytes == 0, if it does we got our reservation and we can carry
90 * on, if not return the appropriate error (ENOSPC, but can be EINTR if we
91 * were interrupted.)
92 *
93 * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
94 *
95 * Same as the above, except we add ourselves to the
96 * space_info->priority_tickets, and we do not use ticket->wait, we simply
97 * call flush_space() ourselves for the states that are safe for us to call
98 * without deadlocking and hope for the best.
99 *
100 * THE FLUSHING STATES
101 *
102 * Generally speaking we will have two cases for each state, a "nice" state
103 * and a "ALL THE THINGS" state. In btrfs we delay a lot of work in order to
104 * reduce the locking over head on the various trees, and even to keep from
105 * doing any work at all in the case of delayed refs. Each of these delayed
106 * things however hold reservations, and so letting them run allows us to
107 * reclaim space so we can make new reservations.
108 *
109 * FLUSH_DELAYED_ITEMS
110 * Every inode has a delayed item to update the inode. Take a simple write
111 * for example, we would update the inode item at write time to update the
112 * mtime, and then again at finish_ordered_io() time in order to update the
113 * isize or bytes. We keep these delayed items to coalesce these operations
114 * into a single operation done on demand. These are an easy way to reclaim
115 * metadata space.
116 *
117 * FLUSH_DELALLOC
118 * Look at the delalloc comment to get an idea of how much space is reserved
119 * for delayed allocation. We can reclaim some of this space simply by
120 * running delalloc, but usually we need to wait for ordered extents to
121 * reclaim the bulk of this space.
122 *
123 * FLUSH_DELAYED_REFS
124 * We have a block reserve for the outstanding delayed refs space, and every
125 * delayed ref operation holds a reservation. Running these is a quick way
126 * to reclaim space, but we want to hold this until the end because COW can
127 * churn a lot and we can avoid making some extent tree modifications if we
128 * are able to delay for as long as possible.
129 *
130 * ALLOC_CHUNK
131 * We will skip this the first time through space reservation, because of
132 * overcommit and we don't want to have a lot of useless metadata space when
133 * our worst case reservations will likely never come true.
134 *
135 * RUN_DELAYED_IPUTS
136 * If we're freeing inodes we're likely freeing checksums, file extent
137 * items, and extent tree items. Loads of space could be freed up by these
138 * operations, however they won't be usable until the transaction commits.
139 *
140 * COMMIT_TRANS
141 * This will commit the transaction. Historically we had a lot of logic
142 * surrounding whether or not we'd commit the transaction, but this waits born
143 * out of a pre-tickets era where we could end up committing the transaction
144 * thousands of times in a row without making progress. Now thanks to our
145 * ticketing system we know if we're not making progress and can error
146 * everybody out after a few commits rather than burning the disk hoping for
147 * a different answer.
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
166u64 __pure btrfs_space_info_used(const 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 */
180void 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/*
190 * Block groups with more than this value (percents) of unusable space will be
191 * scheduled for background reclaim.
192 */
193#define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH (75)
194
195#define BTRFS_UNALLOC_BLOCK_GROUP_TARGET (10ULL)
196
197/*
198 * Calculate chunk size depending on volume type (regular or zoned).
199 */
200static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
201{
202 if (btrfs_is_zoned(fs_info))
203 return fs_info->zone_size;
204
205 ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
206
207 if (flags & BTRFS_BLOCK_GROUP_DATA)
208 return BTRFS_MAX_DATA_CHUNK_SIZE;
209 else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
210 return SZ_32M;
211
212 /* Handle BTRFS_BLOCK_GROUP_METADATA */
213 if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
214 return SZ_1G;
215
216 return SZ_256M;
217}
218
219/*
220 * Update default chunk size.
221 */
222void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
223 u64 chunk_size)
224{
225 WRITE_ONCE(space_info->chunk_size, chunk_size);
226}
227
228static int create_space_info(struct btrfs_fs_info *info, u64 flags)
229{
230
231 struct btrfs_space_info *space_info;
232 int i;
233 int ret;
234
235 space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
236 if (!space_info)
237 return -ENOMEM;
238
239 space_info->fs_info = info;
240 for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
241 INIT_LIST_HEAD(&space_info->block_groups[i]);
242 init_rwsem(&space_info->groups_sem);
243 spin_lock_init(&space_info->lock);
244 space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
245 space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
246 INIT_LIST_HEAD(&space_info->ro_bgs);
247 INIT_LIST_HEAD(&space_info->tickets);
248 INIT_LIST_HEAD(&space_info->priority_tickets);
249 space_info->clamp = 1;
250 btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags));
251
252 if (btrfs_is_zoned(info))
253 space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH;
254
255 ret = btrfs_sysfs_add_space_info_type(info, space_info);
256 if (ret)
257 return ret;
258
259 list_add(&space_info->list, &info->space_info);
260 if (flags & BTRFS_BLOCK_GROUP_DATA)
261 info->data_sinfo = space_info;
262
263 return ret;
264}
265
266int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
267{
268 struct btrfs_super_block *disk_super;
269 u64 features;
270 u64 flags;
271 int mixed = 0;
272 int ret;
273
274 disk_super = fs_info->super_copy;
275 if (!btrfs_super_root(disk_super))
276 return -EINVAL;
277
278 features = btrfs_super_incompat_flags(disk_super);
279 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
280 mixed = 1;
281
282 flags = BTRFS_BLOCK_GROUP_SYSTEM;
283 ret = create_space_info(fs_info, flags);
284 if (ret)
285 goto out;
286
287 if (mixed) {
288 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
289 ret = create_space_info(fs_info, flags);
290 } else {
291 flags = BTRFS_BLOCK_GROUP_METADATA;
292 ret = create_space_info(fs_info, flags);
293 if (ret)
294 goto out;
295
296 flags = BTRFS_BLOCK_GROUP_DATA;
297 ret = create_space_info(fs_info, flags);
298 }
299out:
300 return ret;
301}
302
303void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
304 struct btrfs_block_group *block_group)
305{
306 struct btrfs_space_info *found;
307 int factor, index;
308
309 factor = btrfs_bg_type_to_factor(block_group->flags);
310
311 found = btrfs_find_space_info(info, block_group->flags);
312 ASSERT(found);
313 spin_lock(&found->lock);
314 found->total_bytes += block_group->length;
315 found->disk_total += block_group->length * factor;
316 found->bytes_used += block_group->used;
317 found->disk_used += block_group->used * factor;
318 found->bytes_readonly += block_group->bytes_super;
319 btrfs_space_info_update_bytes_zone_unusable(info, found, block_group->zone_unusable);
320 if (block_group->length > 0)
321 found->full = 0;
322 btrfs_try_granting_tickets(info, found);
323 spin_unlock(&found->lock);
324
325 block_group->space_info = found;
326
327 index = btrfs_bg_flags_to_raid_index(block_group->flags);
328 down_write(&found->groups_sem);
329 list_add_tail(&block_group->list, &found->block_groups[index]);
330 up_write(&found->groups_sem);
331}
332
333struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
334 u64 flags)
335{
336 struct list_head *head = &info->space_info;
337 struct btrfs_space_info *found;
338
339 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
340
341 list_for_each_entry(found, head, list) {
342 if (found->flags & flags)
343 return found;
344 }
345 return NULL;
346}
347
348static u64 calc_effective_data_chunk_size(struct btrfs_fs_info *fs_info)
349{
350 struct btrfs_space_info *data_sinfo;
351 u64 data_chunk_size;
352
353 /*
354 * Calculate the data_chunk_size, space_info->chunk_size is the
355 * "optimal" chunk size based on the fs size. However when we actually
356 * allocate the chunk we will strip this down further, making it no
357 * more than 10% of the disk or 1G, whichever is smaller.
358 *
359 * On the zoned mode, we need to use zone_size (= data_sinfo->chunk_size)
360 * as it is.
361 */
362 data_sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA);
363 if (btrfs_is_zoned(fs_info))
364 return data_sinfo->chunk_size;
365 data_chunk_size = min(data_sinfo->chunk_size,
366 mult_perc(fs_info->fs_devices->total_rw_bytes, 10));
367 return min_t(u64, data_chunk_size, SZ_1G);
368}
369
370static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
371 const struct btrfs_space_info *space_info,
372 enum btrfs_reserve_flush_enum flush)
373{
374 u64 profile;
375 u64 avail;
376 u64 data_chunk_size;
377 int factor;
378
379 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
380 profile = btrfs_system_alloc_profile(fs_info);
381 else
382 profile = btrfs_metadata_alloc_profile(fs_info);
383
384 avail = atomic64_read(&fs_info->free_chunk_space);
385
386 /*
387 * If we have dup, raid1 or raid10 then only half of the free
388 * space is actually usable. For raid56, the space info used
389 * doesn't include the parity drive, so we don't have to
390 * change the math
391 */
392 factor = btrfs_bg_type_to_factor(profile);
393 avail = div_u64(avail, factor);
394 if (avail == 0)
395 return 0;
396
397 data_chunk_size = calc_effective_data_chunk_size(fs_info);
398
399 /*
400 * Since data allocations immediately use block groups as part of the
401 * reservation, because we assume that data reservations will == actual
402 * usage, we could potentially overcommit and then immediately have that
403 * available space used by a data allocation, which could put us in a
404 * bind when we get close to filling the file system.
405 *
406 * To handle this simply remove the data_chunk_size from the available
407 * space. If we are relatively empty this won't affect our ability to
408 * overcommit much, and if we're very close to full it'll keep us from
409 * getting into a position where we've given ourselves very little
410 * metadata wiggle room.
411 */
412 if (avail <= data_chunk_size)
413 return 0;
414 avail -= data_chunk_size;
415
416 /*
417 * If we aren't flushing all things, let us overcommit up to
418 * 1/2th of the space. If we can flush, don't let us overcommit
419 * too much, let it overcommit up to 1/8 of the space.
420 */
421 if (flush == BTRFS_RESERVE_FLUSH_ALL)
422 avail >>= 3;
423 else
424 avail >>= 1;
425
426 /*
427 * On the zoned mode, we always allocate one zone as one chunk.
428 * Returning non-zone size alingned bytes here will result in
429 * less pressure for the async metadata reclaim process, and it
430 * will over-commit too much leading to ENOSPC. Align down to the
431 * zone size to avoid that.
432 */
433 if (btrfs_is_zoned(fs_info))
434 avail = ALIGN_DOWN(avail, fs_info->zone_size);
435
436 return avail;
437}
438
439int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
440 const struct btrfs_space_info *space_info, u64 bytes,
441 enum btrfs_reserve_flush_enum flush)
442{
443 u64 avail;
444 u64 used;
445
446 /* Don't overcommit when in mixed mode */
447 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
448 return 0;
449
450 used = btrfs_space_info_used(space_info, true);
451 avail = calc_available_free_space(fs_info, space_info, flush);
452
453 if (used + bytes < space_info->total_bytes + avail)
454 return 1;
455 return 0;
456}
457
458static void remove_ticket(struct btrfs_space_info *space_info,
459 struct reserve_ticket *ticket)
460{
461 if (!list_empty(&ticket->list)) {
462 list_del_init(&ticket->list);
463 ASSERT(space_info->reclaim_size >= ticket->bytes);
464 space_info->reclaim_size -= ticket->bytes;
465 }
466}
467
468/*
469 * This is for space we already have accounted in space_info->bytes_may_use, so
470 * basically when we're returning space from block_rsv's.
471 */
472void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
473 struct btrfs_space_info *space_info)
474{
475 struct list_head *head;
476 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
477
478 lockdep_assert_held(&space_info->lock);
479
480 head = &space_info->priority_tickets;
481again:
482 while (!list_empty(head)) {
483 struct reserve_ticket *ticket;
484 u64 used = btrfs_space_info_used(space_info, true);
485
486 ticket = list_first_entry(head, struct reserve_ticket, list);
487
488 /* Check and see if our ticket can be satisfied now. */
489 if ((used + ticket->bytes <= space_info->total_bytes) ||
490 btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
491 flush)) {
492 btrfs_space_info_update_bytes_may_use(fs_info,
493 space_info,
494 ticket->bytes);
495 remove_ticket(space_info, ticket);
496 ticket->bytes = 0;
497 space_info->tickets_id++;
498 wake_up(&ticket->wait);
499 } else {
500 break;
501 }
502 }
503
504 if (head == &space_info->priority_tickets) {
505 head = &space_info->tickets;
506 flush = BTRFS_RESERVE_FLUSH_ALL;
507 goto again;
508 }
509}
510
511#define DUMP_BLOCK_RSV(fs_info, rsv_name) \
512do { \
513 struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \
514 spin_lock(&__rsv->lock); \
515 btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \
516 __rsv->size, __rsv->reserved); \
517 spin_unlock(&__rsv->lock); \
518} while (0)
519
520static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info)
521{
522 switch (space_info->flags) {
523 case BTRFS_BLOCK_GROUP_SYSTEM:
524 return "SYSTEM";
525 case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
526 return "DATA+METADATA";
527 case BTRFS_BLOCK_GROUP_DATA:
528 return "DATA";
529 case BTRFS_BLOCK_GROUP_METADATA:
530 return "METADATA";
531 default:
532 return "UNKNOWN";
533 }
534}
535
536static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
537{
538 DUMP_BLOCK_RSV(fs_info, global_block_rsv);
539 DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
540 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
541 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
542 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
543}
544
545static void __btrfs_dump_space_info(const struct btrfs_fs_info *fs_info,
546 const struct btrfs_space_info *info)
547{
548 const char *flag_str = space_info_flag_to_str(info);
549 lockdep_assert_held(&info->lock);
550
551 /* The free space could be negative in case of overcommit */
552 btrfs_info(fs_info, "space_info %s has %lld free, is %sfull",
553 flag_str,
554 (s64)(info->total_bytes - btrfs_space_info_used(info, true)),
555 info->full ? "" : "not ");
556 btrfs_info(fs_info,
557"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
558 info->total_bytes, info->bytes_used, info->bytes_pinned,
559 info->bytes_reserved, info->bytes_may_use,
560 info->bytes_readonly, info->bytes_zone_unusable);
561}
562
563void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
564 struct btrfs_space_info *info, u64 bytes,
565 int dump_block_groups)
566{
567 struct btrfs_block_group *cache;
568 u64 total_avail = 0;
569 int index = 0;
570
571 spin_lock(&info->lock);
572 __btrfs_dump_space_info(fs_info, info);
573 dump_global_block_rsv(fs_info);
574 spin_unlock(&info->lock);
575
576 if (!dump_block_groups)
577 return;
578
579 down_read(&info->groups_sem);
580again:
581 list_for_each_entry(cache, &info->block_groups[index], list) {
582 u64 avail;
583
584 spin_lock(&cache->lock);
585 avail = cache->length - cache->used - cache->pinned -
586 cache->reserved - cache->bytes_super - cache->zone_unusable;
587 btrfs_info(fs_info,
588"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
589 cache->start, cache->length, cache->used, cache->pinned,
590 cache->reserved, cache->delalloc_bytes,
591 cache->bytes_super, cache->zone_unusable,
592 avail, cache->ro ? "[readonly]" : "");
593 spin_unlock(&cache->lock);
594 btrfs_dump_free_space(cache, bytes);
595 total_avail += avail;
596 }
597 if (++index < BTRFS_NR_RAID_TYPES)
598 goto again;
599 up_read(&info->groups_sem);
600
601 btrfs_info(fs_info, "%llu bytes available across all block groups", total_avail);
602}
603
604static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info,
605 u64 to_reclaim)
606{
607 u64 bytes;
608 u64 nr;
609
610 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
611 nr = div64_u64(to_reclaim, bytes);
612 if (!nr)
613 nr = 1;
614 return nr;
615}
616
617/*
618 * shrink metadata reservation for delalloc
619 */
620static void shrink_delalloc(struct btrfs_fs_info *fs_info,
621 struct btrfs_space_info *space_info,
622 u64 to_reclaim, bool wait_ordered,
623 bool for_preempt)
624{
625 struct btrfs_trans_handle *trans;
626 u64 delalloc_bytes;
627 u64 ordered_bytes;
628 u64 items;
629 long time_left;
630 int loops;
631
632 delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
633 ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
634 if (delalloc_bytes == 0 && ordered_bytes == 0)
635 return;
636
637 /* Calc the number of the pages we need flush for space reservation */
638 if (to_reclaim == U64_MAX) {
639 items = U64_MAX;
640 } else {
641 /*
642 * to_reclaim is set to however much metadata we need to
643 * reclaim, but reclaiming that much data doesn't really track
644 * exactly. What we really want to do is reclaim full inode's
645 * worth of reservations, however that's not available to us
646 * here. We will take a fraction of the delalloc bytes for our
647 * flushing loops and hope for the best. Delalloc will expand
648 * the amount we write to cover an entire dirty extent, which
649 * will reclaim the metadata reservation for that range. If
650 * it's not enough subsequent flush stages will be more
651 * aggressive.
652 */
653 to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
654 items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
655 }
656
657 trans = current->journal_info;
658
659 /*
660 * If we are doing more ordered than delalloc we need to just wait on
661 * ordered extents, otherwise we'll waste time trying to flush delalloc
662 * that likely won't give us the space back we need.
663 */
664 if (ordered_bytes > delalloc_bytes && !for_preempt)
665 wait_ordered = true;
666
667 loops = 0;
668 while ((delalloc_bytes || ordered_bytes) && loops < 3) {
669 u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
670 long nr_pages = min_t(u64, temp, LONG_MAX);
671 int async_pages;
672
673 btrfs_start_delalloc_roots(fs_info, nr_pages, true);
674
675 /*
676 * We need to make sure any outstanding async pages are now
677 * processed before we continue. This is because things like
678 * sync_inode() try to be smart and skip writing if the inode is
679 * marked clean. We don't use filemap_fwrite for flushing
680 * because we want to control how many pages we write out at a
681 * time, thus this is the only safe way to make sure we've
682 * waited for outstanding compressed workers to have started
683 * their jobs and thus have ordered extents set up properly.
684 *
685 * This exists because we do not want to wait for each
686 * individual inode to finish its async work, we simply want to
687 * start the IO on everybody, and then come back here and wait
688 * for all of the async work to catch up. Once we're done with
689 * that we know we'll have ordered extents for everything and we
690 * can decide if we wait for that or not.
691 *
692 * If we choose to replace this in the future, make absolutely
693 * sure that the proper waiting is being done in the async case,
694 * as there have been bugs in that area before.
695 */
696 async_pages = atomic_read(&fs_info->async_delalloc_pages);
697 if (!async_pages)
698 goto skip_async;
699
700 /*
701 * We don't want to wait forever, if we wrote less pages in this
702 * loop than we have outstanding, only wait for that number of
703 * pages, otherwise we can wait for all async pages to finish
704 * before continuing.
705 */
706 if (async_pages > nr_pages)
707 async_pages -= nr_pages;
708 else
709 async_pages = 0;
710 wait_event(fs_info->async_submit_wait,
711 atomic_read(&fs_info->async_delalloc_pages) <=
712 async_pages);
713skip_async:
714 loops++;
715 if (wait_ordered && !trans) {
716 btrfs_wait_ordered_roots(fs_info, items, NULL);
717 } else {
718 time_left = schedule_timeout_killable(1);
719 if (time_left)
720 break;
721 }
722
723 /*
724 * If we are for preemption we just want a one-shot of delalloc
725 * flushing so we can stop flushing if we decide we don't need
726 * to anymore.
727 */
728 if (for_preempt)
729 break;
730
731 spin_lock(&space_info->lock);
732 if (list_empty(&space_info->tickets) &&
733 list_empty(&space_info->priority_tickets)) {
734 spin_unlock(&space_info->lock);
735 break;
736 }
737 spin_unlock(&space_info->lock);
738
739 delalloc_bytes = percpu_counter_sum_positive(
740 &fs_info->delalloc_bytes);
741 ordered_bytes = percpu_counter_sum_positive(
742 &fs_info->ordered_bytes);
743 }
744}
745
746/*
747 * Try to flush some data based on policy set by @state. This is only advisory
748 * and may fail for various reasons. The caller is supposed to examine the
749 * state of @space_info to detect the outcome.
750 */
751static void flush_space(struct btrfs_fs_info *fs_info,
752 struct btrfs_space_info *space_info, u64 num_bytes,
753 enum btrfs_flush_state state, bool for_preempt)
754{
755 struct btrfs_root *root = fs_info->tree_root;
756 struct btrfs_trans_handle *trans;
757 int nr;
758 int ret = 0;
759
760 switch (state) {
761 case FLUSH_DELAYED_ITEMS_NR:
762 case FLUSH_DELAYED_ITEMS:
763 if (state == FLUSH_DELAYED_ITEMS_NR)
764 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
765 else
766 nr = -1;
767
768 trans = btrfs_join_transaction_nostart(root);
769 if (IS_ERR(trans)) {
770 ret = PTR_ERR(trans);
771 if (ret == -ENOENT)
772 ret = 0;
773 break;
774 }
775 ret = btrfs_run_delayed_items_nr(trans, nr);
776 btrfs_end_transaction(trans);
777 break;
778 case FLUSH_DELALLOC:
779 case FLUSH_DELALLOC_WAIT:
780 case FLUSH_DELALLOC_FULL:
781 if (state == FLUSH_DELALLOC_FULL)
782 num_bytes = U64_MAX;
783 shrink_delalloc(fs_info, space_info, num_bytes,
784 state != FLUSH_DELALLOC, for_preempt);
785 break;
786 case FLUSH_DELAYED_REFS_NR:
787 case FLUSH_DELAYED_REFS:
788 trans = btrfs_join_transaction_nostart(root);
789 if (IS_ERR(trans)) {
790 ret = PTR_ERR(trans);
791 if (ret == -ENOENT)
792 ret = 0;
793 break;
794 }
795 if (state == FLUSH_DELAYED_REFS_NR)
796 btrfs_run_delayed_refs(trans, num_bytes);
797 else
798 btrfs_run_delayed_refs(trans, 0);
799 btrfs_end_transaction(trans);
800 break;
801 case ALLOC_CHUNK:
802 case ALLOC_CHUNK_FORCE:
803 trans = btrfs_join_transaction(root);
804 if (IS_ERR(trans)) {
805 ret = PTR_ERR(trans);
806 break;
807 }
808 ret = btrfs_chunk_alloc(trans,
809 btrfs_get_alloc_profile(fs_info, space_info->flags),
810 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
811 CHUNK_ALLOC_FORCE);
812 btrfs_end_transaction(trans);
813
814 if (ret > 0 || ret == -ENOSPC)
815 ret = 0;
816 break;
817 case RUN_DELAYED_IPUTS:
818 /*
819 * If we have pending delayed iputs then we could free up a
820 * bunch of pinned space, so make sure we run the iputs before
821 * we do our pinned bytes check below.
822 */
823 btrfs_run_delayed_iputs(fs_info);
824 btrfs_wait_on_delayed_iputs(fs_info);
825 break;
826 case COMMIT_TRANS:
827 ASSERT(current->journal_info == NULL);
828 /*
829 * We don't want to start a new transaction, just attach to the
830 * current one or wait it fully commits in case its commit is
831 * happening at the moment. Note: we don't use a nostart join
832 * because that does not wait for a transaction to fully commit
833 * (only for it to be unblocked, state TRANS_STATE_UNBLOCKED).
834 */
835 ret = btrfs_commit_current_transaction(root);
836 break;
837 default:
838 ret = -ENOSPC;
839 break;
840 }
841
842 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
843 ret, for_preempt);
844 return;
845}
846
847static u64 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
848 const struct btrfs_space_info *space_info)
849{
850 u64 used;
851 u64 avail;
852 u64 to_reclaim = space_info->reclaim_size;
853
854 lockdep_assert_held(&space_info->lock);
855
856 avail = calc_available_free_space(fs_info, space_info,
857 BTRFS_RESERVE_FLUSH_ALL);
858 used = btrfs_space_info_used(space_info, true);
859
860 /*
861 * We may be flushing because suddenly we have less space than we had
862 * before, and now we're well over-committed based on our current free
863 * space. If that's the case add in our overage so we make sure to put
864 * appropriate pressure on the flushing state machine.
865 */
866 if (space_info->total_bytes + avail < used)
867 to_reclaim += used - (space_info->total_bytes + avail);
868
869 return to_reclaim;
870}
871
872static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
873 const struct btrfs_space_info *space_info)
874{
875 const u64 global_rsv_size = btrfs_block_rsv_reserved(&fs_info->global_block_rsv);
876 u64 ordered, delalloc;
877 u64 thresh;
878 u64 used;
879
880 thresh = mult_perc(space_info->total_bytes, 90);
881
882 lockdep_assert_held(&space_info->lock);
883
884 /* If we're just plain full then async reclaim just slows us down. */
885 if ((space_info->bytes_used + space_info->bytes_reserved +
886 global_rsv_size) >= thresh)
887 return false;
888
889 used = space_info->bytes_may_use + space_info->bytes_pinned;
890
891 /* The total flushable belongs to the global rsv, don't flush. */
892 if (global_rsv_size >= used)
893 return false;
894
895 /*
896 * 128MiB is 1/4 of the maximum global rsv size. If we have less than
897 * that devoted to other reservations then there's no sense in flushing,
898 * we don't have a lot of things that need flushing.
899 */
900 if (used - global_rsv_size <= SZ_128M)
901 return false;
902
903 /*
904 * We have tickets queued, bail so we don't compete with the async
905 * flushers.
906 */
907 if (space_info->reclaim_size)
908 return false;
909
910 /*
911 * If we have over half of the free space occupied by reservations or
912 * pinned then we want to start flushing.
913 *
914 * We do not do the traditional thing here, which is to say
915 *
916 * if (used >= ((total_bytes + avail) / 2))
917 * return 1;
918 *
919 * because this doesn't quite work how we want. If we had more than 50%
920 * of the space_info used by bytes_used and we had 0 available we'd just
921 * constantly run the background flusher. Instead we want it to kick in
922 * if our reclaimable space exceeds our clamped free space.
923 *
924 * Our clamping range is 2^1 -> 2^8. Practically speaking that means
925 * the following:
926 *
927 * Amount of RAM Minimum threshold Maximum threshold
928 *
929 * 256GiB 1GiB 128GiB
930 * 128GiB 512MiB 64GiB
931 * 64GiB 256MiB 32GiB
932 * 32GiB 128MiB 16GiB
933 * 16GiB 64MiB 8GiB
934 *
935 * These are the range our thresholds will fall in, corresponding to how
936 * much delalloc we need for the background flusher to kick in.
937 */
938
939 thresh = calc_available_free_space(fs_info, space_info,
940 BTRFS_RESERVE_FLUSH_ALL);
941 used = space_info->bytes_used + space_info->bytes_reserved +
942 space_info->bytes_readonly + global_rsv_size;
943 if (used < space_info->total_bytes)
944 thresh += space_info->total_bytes - used;
945 thresh >>= space_info->clamp;
946
947 used = space_info->bytes_pinned;
948
949 /*
950 * If we have more ordered bytes than delalloc bytes then we're either
951 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
952 * around. Preemptive flushing is only useful in that it can free up
953 * space before tickets need to wait for things to finish. In the case
954 * of ordered extents, preemptively waiting on ordered extents gets us
955 * nothing, if our reservations are tied up in ordered extents we'll
956 * simply have to slow down writers by forcing them to wait on ordered
957 * extents.
958 *
959 * In the case that ordered is larger than delalloc, only include the
960 * block reserves that we would actually be able to directly reclaim
961 * from. In this case if we're heavy on metadata operations this will
962 * clearly be heavy enough to warrant preemptive flushing. In the case
963 * of heavy DIO or ordered reservations, preemptive flushing will just
964 * waste time and cause us to slow down.
965 *
966 * We want to make sure we truly are maxed out on ordered however, so
967 * cut ordered in half, and if it's still higher than delalloc then we
968 * can keep flushing. This is to avoid the case where we start
969 * flushing, and now delalloc == ordered and we stop preemptively
970 * flushing when we could still have several gigs of delalloc to flush.
971 */
972 ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
973 delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
974 if (ordered >= delalloc)
975 used += btrfs_block_rsv_reserved(&fs_info->delayed_refs_rsv) +
976 btrfs_block_rsv_reserved(&fs_info->delayed_block_rsv);
977 else
978 used += space_info->bytes_may_use - global_rsv_size;
979
980 return (used >= thresh && !btrfs_fs_closing(fs_info) &&
981 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
982}
983
984static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
985 struct btrfs_space_info *space_info,
986 struct reserve_ticket *ticket)
987{
988 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
989 u64 min_bytes;
990
991 if (!ticket->steal)
992 return false;
993
994 if (global_rsv->space_info != space_info)
995 return false;
996
997 spin_lock(&global_rsv->lock);
998 min_bytes = mult_perc(global_rsv->size, 10);
999 if (global_rsv->reserved < min_bytes + ticket->bytes) {
1000 spin_unlock(&global_rsv->lock);
1001 return false;
1002 }
1003 global_rsv->reserved -= ticket->bytes;
1004 remove_ticket(space_info, ticket);
1005 ticket->bytes = 0;
1006 wake_up(&ticket->wait);
1007 space_info->tickets_id++;
1008 if (global_rsv->reserved < global_rsv->size)
1009 global_rsv->full = 0;
1010 spin_unlock(&global_rsv->lock);
1011
1012 return true;
1013}
1014
1015/*
1016 * We've exhausted our flushing, start failing tickets.
1017 *
1018 * @fs_info - fs_info for this fs
1019 * @space_info - the space info we were flushing
1020 *
1021 * We call this when we've exhausted our flushing ability and haven't made
1022 * progress in satisfying tickets. The reservation code handles tickets in
1023 * order, so if there is a large ticket first and then smaller ones we could
1024 * very well satisfy the smaller tickets. This will attempt to wake up any
1025 * tickets in the list to catch this case.
1026 *
1027 * This function returns true if it was able to make progress by clearing out
1028 * other tickets, or if it stumbles across a ticket that was smaller than the
1029 * first ticket.
1030 */
1031static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
1032 struct btrfs_space_info *space_info)
1033{
1034 struct reserve_ticket *ticket;
1035 u64 tickets_id = space_info->tickets_id;
1036 const bool aborted = BTRFS_FS_ERROR(fs_info);
1037
1038 trace_btrfs_fail_all_tickets(fs_info, space_info);
1039
1040 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
1041 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
1042 __btrfs_dump_space_info(fs_info, space_info);
1043 }
1044
1045 while (!list_empty(&space_info->tickets) &&
1046 tickets_id == space_info->tickets_id) {
1047 ticket = list_first_entry(&space_info->tickets,
1048 struct reserve_ticket, list);
1049
1050 if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket))
1051 return true;
1052
1053 if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1054 btrfs_info(fs_info, "failing ticket with %llu bytes",
1055 ticket->bytes);
1056
1057 remove_ticket(space_info, ticket);
1058 if (aborted)
1059 ticket->error = -EIO;
1060 else
1061 ticket->error = -ENOSPC;
1062 wake_up(&ticket->wait);
1063
1064 /*
1065 * We're just throwing tickets away, so more flushing may not
1066 * trip over btrfs_try_granting_tickets, so we need to call it
1067 * here to see if we can make progress with the next ticket in
1068 * the list.
1069 */
1070 if (!aborted)
1071 btrfs_try_granting_tickets(fs_info, space_info);
1072 }
1073 return (tickets_id != space_info->tickets_id);
1074}
1075
1076/*
1077 * This is for normal flushers, we can wait all goddamned day if we want to. We
1078 * will loop and continuously try to flush as long as we are making progress.
1079 * We count progress as clearing off tickets each time we have to loop.
1080 */
1081static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
1082{
1083 struct btrfs_fs_info *fs_info;
1084 struct btrfs_space_info *space_info;
1085 u64 to_reclaim;
1086 enum btrfs_flush_state flush_state;
1087 int commit_cycles = 0;
1088 u64 last_tickets_id;
1089
1090 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
1091 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1092
1093 spin_lock(&space_info->lock);
1094 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1095 if (!to_reclaim) {
1096 space_info->flush = 0;
1097 spin_unlock(&space_info->lock);
1098 return;
1099 }
1100 last_tickets_id = space_info->tickets_id;
1101 spin_unlock(&space_info->lock);
1102
1103 flush_state = FLUSH_DELAYED_ITEMS_NR;
1104 do {
1105 flush_space(fs_info, space_info, to_reclaim, flush_state, false);
1106 spin_lock(&space_info->lock);
1107 if (list_empty(&space_info->tickets)) {
1108 space_info->flush = 0;
1109 spin_unlock(&space_info->lock);
1110 return;
1111 }
1112 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1113 space_info);
1114 if (last_tickets_id == space_info->tickets_id) {
1115 flush_state++;
1116 } else {
1117 last_tickets_id = space_info->tickets_id;
1118 flush_state = FLUSH_DELAYED_ITEMS_NR;
1119 if (commit_cycles)
1120 commit_cycles--;
1121 }
1122
1123 /*
1124 * We do not want to empty the system of delalloc unless we're
1125 * under heavy pressure, so allow one trip through the flushing
1126 * logic before we start doing a FLUSH_DELALLOC_FULL.
1127 */
1128 if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
1129 flush_state++;
1130
1131 /*
1132 * We don't want to force a chunk allocation until we've tried
1133 * pretty hard to reclaim space. Think of the case where we
1134 * freed up a bunch of space and so have a lot of pinned space
1135 * to reclaim. We would rather use that than possibly create a
1136 * underutilized metadata chunk. So if this is our first run
1137 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1138 * commit the transaction. If nothing has changed the next go
1139 * around then we can force a chunk allocation.
1140 */
1141 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1142 flush_state++;
1143
1144 if (flush_state > COMMIT_TRANS) {
1145 commit_cycles++;
1146 if (commit_cycles > 2) {
1147 if (maybe_fail_all_tickets(fs_info, space_info)) {
1148 flush_state = FLUSH_DELAYED_ITEMS_NR;
1149 commit_cycles--;
1150 } else {
1151 space_info->flush = 0;
1152 }
1153 } else {
1154 flush_state = FLUSH_DELAYED_ITEMS_NR;
1155 }
1156 }
1157 spin_unlock(&space_info->lock);
1158 } while (flush_state <= COMMIT_TRANS);
1159}
1160
1161/*
1162 * This handles pre-flushing of metadata space before we get to the point that
1163 * we need to start blocking threads on tickets. The logic here is different
1164 * from the other flush paths because it doesn't rely on tickets to tell us how
1165 * much we need to flush, instead it attempts to keep us below the 80% full
1166 * watermark of space by flushing whichever reservation pool is currently the
1167 * largest.
1168 */
1169static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
1170{
1171 struct btrfs_fs_info *fs_info;
1172 struct btrfs_space_info *space_info;
1173 struct btrfs_block_rsv *delayed_block_rsv;
1174 struct btrfs_block_rsv *delayed_refs_rsv;
1175 struct btrfs_block_rsv *global_rsv;
1176 struct btrfs_block_rsv *trans_rsv;
1177 int loops = 0;
1178
1179 fs_info = container_of(work, struct btrfs_fs_info,
1180 preempt_reclaim_work);
1181 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1182 delayed_block_rsv = &fs_info->delayed_block_rsv;
1183 delayed_refs_rsv = &fs_info->delayed_refs_rsv;
1184 global_rsv = &fs_info->global_block_rsv;
1185 trans_rsv = &fs_info->trans_block_rsv;
1186
1187 spin_lock(&space_info->lock);
1188 while (need_preemptive_reclaim(fs_info, space_info)) {
1189 enum btrfs_flush_state flush;
1190 u64 delalloc_size = 0;
1191 u64 to_reclaim, block_rsv_size;
1192 const u64 global_rsv_size = btrfs_block_rsv_reserved(global_rsv);
1193
1194 loops++;
1195
1196 /*
1197 * We don't have a precise counter for the metadata being
1198 * reserved for delalloc, so we'll approximate it by subtracting
1199 * out the block rsv's space from the bytes_may_use. If that
1200 * amount is higher than the individual reserves, then we can
1201 * assume it's tied up in delalloc reservations.
1202 */
1203 block_rsv_size = global_rsv_size +
1204 btrfs_block_rsv_reserved(delayed_block_rsv) +
1205 btrfs_block_rsv_reserved(delayed_refs_rsv) +
1206 btrfs_block_rsv_reserved(trans_rsv);
1207 if (block_rsv_size < space_info->bytes_may_use)
1208 delalloc_size = space_info->bytes_may_use - block_rsv_size;
1209
1210 /*
1211 * We don't want to include the global_rsv in our calculation,
1212 * because that's space we can't touch. Subtract it from the
1213 * block_rsv_size for the next checks.
1214 */
1215 block_rsv_size -= global_rsv_size;
1216
1217 /*
1218 * We really want to avoid flushing delalloc too much, as it
1219 * could result in poor allocation patterns, so only flush it if
1220 * it's larger than the rest of the pools combined.
1221 */
1222 if (delalloc_size > block_rsv_size) {
1223 to_reclaim = delalloc_size;
1224 flush = FLUSH_DELALLOC;
1225 } else if (space_info->bytes_pinned >
1226 (btrfs_block_rsv_reserved(delayed_block_rsv) +
1227 btrfs_block_rsv_reserved(delayed_refs_rsv))) {
1228 to_reclaim = space_info->bytes_pinned;
1229 flush = COMMIT_TRANS;
1230 } else if (btrfs_block_rsv_reserved(delayed_block_rsv) >
1231 btrfs_block_rsv_reserved(delayed_refs_rsv)) {
1232 to_reclaim = btrfs_block_rsv_reserved(delayed_block_rsv);
1233 flush = FLUSH_DELAYED_ITEMS_NR;
1234 } else {
1235 to_reclaim = btrfs_block_rsv_reserved(delayed_refs_rsv);
1236 flush = FLUSH_DELAYED_REFS_NR;
1237 }
1238
1239 spin_unlock(&space_info->lock);
1240
1241 /*
1242 * We don't want to reclaim everything, just a portion, so scale
1243 * down the to_reclaim by 1/4. If it takes us down to 0,
1244 * reclaim 1 items worth.
1245 */
1246 to_reclaim >>= 2;
1247 if (!to_reclaim)
1248 to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1249 flush_space(fs_info, space_info, to_reclaim, flush, true);
1250 cond_resched();
1251 spin_lock(&space_info->lock);
1252 }
1253
1254 /* We only went through once, back off our clamping. */
1255 if (loops == 1 && !space_info->reclaim_size)
1256 space_info->clamp = max(1, space_info->clamp - 1);
1257 trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1258 spin_unlock(&space_info->lock);
1259}
1260
1261/*
1262 * FLUSH_DELALLOC_WAIT:
1263 * Space is freed from flushing delalloc in one of two ways.
1264 *
1265 * 1) compression is on and we allocate less space than we reserved
1266 * 2) we are overwriting existing space
1267 *
1268 * For #1 that extra space is reclaimed as soon as the delalloc pages are
1269 * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1270 * length to ->bytes_reserved, and subtracts the reserved space from
1271 * ->bytes_may_use.
1272 *
1273 * For #2 this is trickier. Once the ordered extent runs we will drop the
1274 * extent in the range we are overwriting, which creates a delayed ref for
1275 * that freed extent. This however is not reclaimed until the transaction
1276 * commits, thus the next stages.
1277 *
1278 * RUN_DELAYED_IPUTS
1279 * If we are freeing inodes, we want to make sure all delayed iputs have
1280 * completed, because they could have been on an inode with i_nlink == 0, and
1281 * thus have been truncated and freed up space. But again this space is not
1282 * immediately reusable, it comes in the form of a delayed ref, which must be
1283 * run and then the transaction must be committed.
1284 *
1285 * COMMIT_TRANS
1286 * This is where we reclaim all of the pinned space generated by running the
1287 * iputs
1288 *
1289 * ALLOC_CHUNK_FORCE
1290 * For data we start with alloc chunk force, however we could have been full
1291 * before, and then the transaction commit could have freed new block groups,
1292 * so if we now have space to allocate do the force chunk allocation.
1293 */
1294static const enum btrfs_flush_state data_flush_states[] = {
1295 FLUSH_DELALLOC_FULL,
1296 RUN_DELAYED_IPUTS,
1297 COMMIT_TRANS,
1298 ALLOC_CHUNK_FORCE,
1299};
1300
1301static void btrfs_async_reclaim_data_space(struct work_struct *work)
1302{
1303 struct btrfs_fs_info *fs_info;
1304 struct btrfs_space_info *space_info;
1305 u64 last_tickets_id;
1306 enum btrfs_flush_state flush_state = 0;
1307
1308 fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1309 space_info = fs_info->data_sinfo;
1310
1311 spin_lock(&space_info->lock);
1312 if (list_empty(&space_info->tickets)) {
1313 space_info->flush = 0;
1314 spin_unlock(&space_info->lock);
1315 return;
1316 }
1317 last_tickets_id = space_info->tickets_id;
1318 spin_unlock(&space_info->lock);
1319
1320 while (!space_info->full) {
1321 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1322 spin_lock(&space_info->lock);
1323 if (list_empty(&space_info->tickets)) {
1324 space_info->flush = 0;
1325 spin_unlock(&space_info->lock);
1326 return;
1327 }
1328
1329 /* Something happened, fail everything and bail. */
1330 if (BTRFS_FS_ERROR(fs_info))
1331 goto aborted_fs;
1332 last_tickets_id = space_info->tickets_id;
1333 spin_unlock(&space_info->lock);
1334 }
1335
1336 while (flush_state < ARRAY_SIZE(data_flush_states)) {
1337 flush_space(fs_info, space_info, U64_MAX,
1338 data_flush_states[flush_state], false);
1339 spin_lock(&space_info->lock);
1340 if (list_empty(&space_info->tickets)) {
1341 space_info->flush = 0;
1342 spin_unlock(&space_info->lock);
1343 return;
1344 }
1345
1346 if (last_tickets_id == space_info->tickets_id) {
1347 flush_state++;
1348 } else {
1349 last_tickets_id = space_info->tickets_id;
1350 flush_state = 0;
1351 }
1352
1353 if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1354 if (space_info->full) {
1355 if (maybe_fail_all_tickets(fs_info, space_info))
1356 flush_state = 0;
1357 else
1358 space_info->flush = 0;
1359 } else {
1360 flush_state = 0;
1361 }
1362
1363 /* Something happened, fail everything and bail. */
1364 if (BTRFS_FS_ERROR(fs_info))
1365 goto aborted_fs;
1366
1367 }
1368 spin_unlock(&space_info->lock);
1369 }
1370 return;
1371
1372aborted_fs:
1373 maybe_fail_all_tickets(fs_info, space_info);
1374 space_info->flush = 0;
1375 spin_unlock(&space_info->lock);
1376}
1377
1378void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1379{
1380 INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1381 INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1382 INIT_WORK(&fs_info->preempt_reclaim_work,
1383 btrfs_preempt_reclaim_metadata_space);
1384}
1385
1386static const enum btrfs_flush_state priority_flush_states[] = {
1387 FLUSH_DELAYED_ITEMS_NR,
1388 FLUSH_DELAYED_ITEMS,
1389 ALLOC_CHUNK,
1390};
1391
1392static const enum btrfs_flush_state evict_flush_states[] = {
1393 FLUSH_DELAYED_ITEMS_NR,
1394 FLUSH_DELAYED_ITEMS,
1395 FLUSH_DELAYED_REFS_NR,
1396 FLUSH_DELAYED_REFS,
1397 FLUSH_DELALLOC,
1398 FLUSH_DELALLOC_WAIT,
1399 FLUSH_DELALLOC_FULL,
1400 ALLOC_CHUNK,
1401 COMMIT_TRANS,
1402};
1403
1404static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1405 struct btrfs_space_info *space_info,
1406 struct reserve_ticket *ticket,
1407 const enum btrfs_flush_state *states,
1408 int states_nr)
1409{
1410 u64 to_reclaim;
1411 int flush_state = 0;
1412
1413 spin_lock(&space_info->lock);
1414 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1415 /*
1416 * This is the priority reclaim path, so to_reclaim could be >0 still
1417 * because we may have only satisfied the priority tickets and still
1418 * left non priority tickets on the list. We would then have
1419 * to_reclaim but ->bytes == 0.
1420 */
1421 if (ticket->bytes == 0) {
1422 spin_unlock(&space_info->lock);
1423 return;
1424 }
1425
1426 while (flush_state < states_nr) {
1427 spin_unlock(&space_info->lock);
1428 flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1429 false);
1430 flush_state++;
1431 spin_lock(&space_info->lock);
1432 if (ticket->bytes == 0) {
1433 spin_unlock(&space_info->lock);
1434 return;
1435 }
1436 }
1437
1438 /*
1439 * Attempt to steal from the global rsv if we can, except if the fs was
1440 * turned into error mode due to a transaction abort when flushing space
1441 * above, in that case fail with the abort error instead of returning
1442 * success to the caller if we can steal from the global rsv - this is
1443 * just to have caller fail immeditelly instead of later when trying to
1444 * modify the fs, making it easier to debug -ENOSPC problems.
1445 */
1446 if (BTRFS_FS_ERROR(fs_info)) {
1447 ticket->error = BTRFS_FS_ERROR(fs_info);
1448 remove_ticket(space_info, ticket);
1449 } else if (!steal_from_global_rsv(fs_info, space_info, ticket)) {
1450 ticket->error = -ENOSPC;
1451 remove_ticket(space_info, ticket);
1452 }
1453
1454 /*
1455 * We must run try_granting_tickets here because we could be a large
1456 * ticket in front of a smaller ticket that can now be satisfied with
1457 * the available space.
1458 */
1459 btrfs_try_granting_tickets(fs_info, space_info);
1460 spin_unlock(&space_info->lock);
1461}
1462
1463static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1464 struct btrfs_space_info *space_info,
1465 struct reserve_ticket *ticket)
1466{
1467 spin_lock(&space_info->lock);
1468
1469 /* We could have been granted before we got here. */
1470 if (ticket->bytes == 0) {
1471 spin_unlock(&space_info->lock);
1472 return;
1473 }
1474
1475 while (!space_info->full) {
1476 spin_unlock(&space_info->lock);
1477 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1478 spin_lock(&space_info->lock);
1479 if (ticket->bytes == 0) {
1480 spin_unlock(&space_info->lock);
1481 return;
1482 }
1483 }
1484
1485 ticket->error = -ENOSPC;
1486 remove_ticket(space_info, ticket);
1487 btrfs_try_granting_tickets(fs_info, space_info);
1488 spin_unlock(&space_info->lock);
1489}
1490
1491static void wait_reserve_ticket(struct btrfs_space_info *space_info,
1492 struct reserve_ticket *ticket)
1493
1494{
1495 DEFINE_WAIT(wait);
1496 int ret = 0;
1497
1498 spin_lock(&space_info->lock);
1499 while (ticket->bytes > 0 && ticket->error == 0) {
1500 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1501 if (ret) {
1502 /*
1503 * Delete us from the list. After we unlock the space
1504 * info, we don't want the async reclaim job to reserve
1505 * space for this ticket. If that would happen, then the
1506 * ticket's task would not known that space was reserved
1507 * despite getting an error, resulting in a space leak
1508 * (bytes_may_use counter of our space_info).
1509 */
1510 remove_ticket(space_info, ticket);
1511 ticket->error = -EINTR;
1512 break;
1513 }
1514 spin_unlock(&space_info->lock);
1515
1516 schedule();
1517
1518 finish_wait(&ticket->wait, &wait);
1519 spin_lock(&space_info->lock);
1520 }
1521 spin_unlock(&space_info->lock);
1522}
1523
1524/*
1525 * Do the appropriate flushing and waiting for a ticket.
1526 *
1527 * @fs_info: the filesystem
1528 * @space_info: space info for the reservation
1529 * @ticket: ticket for the reservation
1530 * @start_ns: timestamp when the reservation started
1531 * @orig_bytes: amount of bytes originally reserved
1532 * @flush: how much we can flush
1533 *
1534 * This does the work of figuring out how to flush for the ticket, waiting for
1535 * the reservation, and returning the appropriate error if there is one.
1536 */
1537static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1538 struct btrfs_space_info *space_info,
1539 struct reserve_ticket *ticket,
1540 u64 start_ns, u64 orig_bytes,
1541 enum btrfs_reserve_flush_enum flush)
1542{
1543 int ret;
1544
1545 switch (flush) {
1546 case BTRFS_RESERVE_FLUSH_DATA:
1547 case BTRFS_RESERVE_FLUSH_ALL:
1548 case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1549 wait_reserve_ticket(space_info, ticket);
1550 break;
1551 case BTRFS_RESERVE_FLUSH_LIMIT:
1552 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1553 priority_flush_states,
1554 ARRAY_SIZE(priority_flush_states));
1555 break;
1556 case BTRFS_RESERVE_FLUSH_EVICT:
1557 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1558 evict_flush_states,
1559 ARRAY_SIZE(evict_flush_states));
1560 break;
1561 case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1562 priority_reclaim_data_space(fs_info, space_info, ticket);
1563 break;
1564 default:
1565 ASSERT(0);
1566 break;
1567 }
1568
1569 ret = ticket->error;
1570 ASSERT(list_empty(&ticket->list));
1571 /*
1572 * Check that we can't have an error set if the reservation succeeded,
1573 * as that would confuse tasks and lead them to error out without
1574 * releasing reserved space (if an error happens the expectation is that
1575 * space wasn't reserved at all).
1576 */
1577 ASSERT(!(ticket->bytes == 0 && ticket->error));
1578 trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1579 start_ns, flush, ticket->error);
1580 return ret;
1581}
1582
1583/*
1584 * This returns true if this flush state will go through the ordinary flushing
1585 * code.
1586 */
1587static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1588{
1589 return (flush == BTRFS_RESERVE_FLUSH_ALL) ||
1590 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1591}
1592
1593static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1594 struct btrfs_space_info *space_info)
1595{
1596 u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1597 u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1598
1599 /*
1600 * If we're heavy on ordered operations then clamping won't help us. We
1601 * need to clamp specifically to keep up with dirty'ing buffered
1602 * writers, because there's not a 1:1 correlation of writing delalloc
1603 * and freeing space, like there is with flushing delayed refs or
1604 * delayed nodes. If we're already more ordered than delalloc then
1605 * we're keeping up, otherwise we aren't and should probably clamp.
1606 */
1607 if (ordered < delalloc)
1608 space_info->clamp = min(space_info->clamp + 1, 8);
1609}
1610
1611static inline bool can_steal(enum btrfs_reserve_flush_enum flush)
1612{
1613 return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1614 flush == BTRFS_RESERVE_FLUSH_EVICT);
1615}
1616
1617/*
1618 * NO_FLUSH and FLUSH_EMERGENCY don't want to create a ticket, they just want to
1619 * fail as quickly as possible.
1620 */
1621static inline bool can_ticket(enum btrfs_reserve_flush_enum flush)
1622{
1623 return (flush != BTRFS_RESERVE_NO_FLUSH &&
1624 flush != BTRFS_RESERVE_FLUSH_EMERGENCY);
1625}
1626
1627/*
1628 * Try to reserve bytes from the block_rsv's space.
1629 *
1630 * @fs_info: the filesystem
1631 * @space_info: space info we want to allocate from
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 */
1642static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1643 struct btrfs_space_info *space_info, u64 orig_bytes,
1644 enum btrfs_reserve_flush_enum flush)
1645{
1646 struct work_struct *async_work;
1647 struct reserve_ticket ticket;
1648 u64 start_ns = 0;
1649 u64 used;
1650 int ret = -ENOSPC;
1651 bool pending_tickets;
1652
1653 ASSERT(orig_bytes);
1654 /*
1655 * If have a transaction handle (current->journal_info != NULL), then
1656 * the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor
1657 * BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those
1658 * flushing methods can trigger transaction commits.
1659 */
1660 if (current->journal_info) {
1661 /* One assert per line for easier debugging. */
1662 ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL);
1663 ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL);
1664 ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT);
1665 }
1666
1667 if (flush == BTRFS_RESERVE_FLUSH_DATA)
1668 async_work = &fs_info->async_data_reclaim_work;
1669 else
1670 async_work = &fs_info->async_reclaim_work;
1671
1672 spin_lock(&space_info->lock);
1673 used = btrfs_space_info_used(space_info, true);
1674
1675 /*
1676 * We don't want NO_FLUSH allocations to jump everybody, they can
1677 * generally handle ENOSPC in a different way, so treat them the same as
1678 * normal flushers when it comes to skipping pending tickets.
1679 */
1680 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1681 pending_tickets = !list_empty(&space_info->tickets) ||
1682 !list_empty(&space_info->priority_tickets);
1683 else
1684 pending_tickets = !list_empty(&space_info->priority_tickets);
1685
1686 /*
1687 * Carry on if we have enough space (short-circuit) OR call
1688 * can_overcommit() to ensure we can overcommit to continue.
1689 */
1690 if (!pending_tickets &&
1691 ((used + orig_bytes <= space_info->total_bytes) ||
1692 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1693 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1694 orig_bytes);
1695 ret = 0;
1696 }
1697
1698 /*
1699 * Things are dire, we need to make a reservation so we don't abort. We
1700 * will let this reservation go through as long as we have actual space
1701 * left to allocate for the block.
1702 */
1703 if (ret && unlikely(flush == BTRFS_RESERVE_FLUSH_EMERGENCY)) {
1704 used = btrfs_space_info_used(space_info, false);
1705 if (used + orig_bytes <= space_info->total_bytes) {
1706 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1707 orig_bytes);
1708 ret = 0;
1709 }
1710 }
1711
1712 /*
1713 * If we couldn't make a reservation then setup our reservation ticket
1714 * and kick the async worker if it's not already running.
1715 *
1716 * If we are a priority flusher then we just need to add our ticket to
1717 * the list and we will do our own flushing further down.
1718 */
1719 if (ret && can_ticket(flush)) {
1720 ticket.bytes = orig_bytes;
1721 ticket.error = 0;
1722 space_info->reclaim_size += ticket.bytes;
1723 init_waitqueue_head(&ticket.wait);
1724 ticket.steal = can_steal(flush);
1725 if (trace_btrfs_reserve_ticket_enabled())
1726 start_ns = ktime_get_ns();
1727
1728 if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1729 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1730 flush == BTRFS_RESERVE_FLUSH_DATA) {
1731 list_add_tail(&ticket.list, &space_info->tickets);
1732 if (!space_info->flush) {
1733 /*
1734 * We were forced to add a reserve ticket, so
1735 * our preemptive flushing is unable to keep
1736 * up. Clamp down on the threshold for the
1737 * preemptive flushing in order to keep up with
1738 * the workload.
1739 */
1740 maybe_clamp_preempt(fs_info, space_info);
1741
1742 space_info->flush = 1;
1743 trace_btrfs_trigger_flush(fs_info,
1744 space_info->flags,
1745 orig_bytes, flush,
1746 "enospc");
1747 queue_work(system_unbound_wq, async_work);
1748 }
1749 } else {
1750 list_add_tail(&ticket.list,
1751 &space_info->priority_tickets);
1752 }
1753 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1754 /*
1755 * We will do the space reservation dance during log replay,
1756 * which means we won't have fs_info->fs_root set, so don't do
1757 * the async reclaim as we will panic.
1758 */
1759 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1760 !work_busy(&fs_info->preempt_reclaim_work) &&
1761 need_preemptive_reclaim(fs_info, space_info)) {
1762 trace_btrfs_trigger_flush(fs_info, space_info->flags,
1763 orig_bytes, flush, "preempt");
1764 queue_work(system_unbound_wq,
1765 &fs_info->preempt_reclaim_work);
1766 }
1767 }
1768 spin_unlock(&space_info->lock);
1769 if (!ret || !can_ticket(flush))
1770 return ret;
1771
1772 return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1773 orig_bytes, flush);
1774}
1775
1776/*
1777 * Try to reserve metadata bytes from the block_rsv's space.
1778 *
1779 * @fs_info: the filesystem
1780 * @space_info: the space_info we're allocating for
1781 * @orig_bytes: number of bytes we want
1782 * @flush: whether or not we can flush to make our reservation
1783 *
1784 * This will reserve orig_bytes number of bytes from the space info associated
1785 * with the block_rsv. If there is not enough space it will make an attempt to
1786 * flush out space to make room. It will do this by flushing delalloc if
1787 * possible or committing the transaction. If flush is 0 then no attempts to
1788 * regain reservations will be made and this will fail if there is not enough
1789 * space already.
1790 */
1791int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1792 struct btrfs_space_info *space_info,
1793 u64 orig_bytes,
1794 enum btrfs_reserve_flush_enum flush)
1795{
1796 int ret;
1797
1798 ret = __reserve_bytes(fs_info, space_info, orig_bytes, flush);
1799 if (ret == -ENOSPC) {
1800 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1801 space_info->flags, orig_bytes, 1);
1802
1803 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1804 btrfs_dump_space_info(fs_info, space_info, orig_bytes, 0);
1805 }
1806 return ret;
1807}
1808
1809/*
1810 * Try to reserve data bytes for an allocation.
1811 *
1812 * @fs_info: the filesystem
1813 * @bytes: number of bytes we need
1814 * @flush: how we are allowed to flush
1815 *
1816 * This will reserve bytes from the data space info. If there is not enough
1817 * space then we will attempt to flush space as specified by flush.
1818 */
1819int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1820 enum btrfs_reserve_flush_enum flush)
1821{
1822 struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1823 int ret;
1824
1825 ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1826 flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE ||
1827 flush == BTRFS_RESERVE_NO_FLUSH);
1828 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1829
1830 ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1831 if (ret == -ENOSPC) {
1832 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1833 data_sinfo->flags, bytes, 1);
1834 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1835 btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
1836 }
1837 return ret;
1838}
1839
1840/* Dump all the space infos when we abort a transaction due to ENOSPC. */
1841__cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
1842{
1843 struct btrfs_space_info *space_info;
1844
1845 btrfs_info(fs_info, "dumping space info:");
1846 list_for_each_entry(space_info, &fs_info->space_info, list) {
1847 spin_lock(&space_info->lock);
1848 __btrfs_dump_space_info(fs_info, space_info);
1849 spin_unlock(&space_info->lock);
1850 }
1851 dump_global_block_rsv(fs_info);
1852}
1853
1854/*
1855 * Account the unused space of all the readonly block group in the space_info.
1856 * takes mirrors into account.
1857 */
1858u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
1859{
1860 struct btrfs_block_group *block_group;
1861 u64 free_bytes = 0;
1862 int factor;
1863
1864 /* It's df, we don't care if it's racy */
1865 if (list_empty(&sinfo->ro_bgs))
1866 return 0;
1867
1868 spin_lock(&sinfo->lock);
1869 list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
1870 spin_lock(&block_group->lock);
1871
1872 if (!block_group->ro) {
1873 spin_unlock(&block_group->lock);
1874 continue;
1875 }
1876
1877 factor = btrfs_bg_type_to_factor(block_group->flags);
1878 free_bytes += (block_group->length -
1879 block_group->used) * factor;
1880
1881 spin_unlock(&block_group->lock);
1882 }
1883 spin_unlock(&sinfo->lock);
1884
1885 return free_bytes;
1886}
1887
1888static u64 calc_pct_ratio(u64 x, u64 y)
1889{
1890 int err;
1891
1892 if (!y)
1893 return 0;
1894again:
1895 err = check_mul_overflow(100, x, &x);
1896 if (err)
1897 goto lose_precision;
1898 return div64_u64(x, y);
1899lose_precision:
1900 x >>= 10;
1901 y >>= 10;
1902 if (!y)
1903 y = 1;
1904 goto again;
1905}
1906
1907/*
1908 * A reasonable buffer for unallocated space is 10 data block_groups.
1909 * If we claw this back repeatedly, we can still achieve efficient
1910 * utilization when near full, and not do too much reclaim while
1911 * always maintaining a solid buffer for workloads that quickly
1912 * allocate and pressure the unallocated space.
1913 */
1914static u64 calc_unalloc_target(struct btrfs_fs_info *fs_info)
1915{
1916 u64 chunk_sz = calc_effective_data_chunk_size(fs_info);
1917
1918 return BTRFS_UNALLOC_BLOCK_GROUP_TARGET * chunk_sz;
1919}
1920
1921/*
1922 * The fundamental goal of automatic reclaim is to protect the filesystem's
1923 * unallocated space and thus minimize the probability of the filesystem going
1924 * read only when a metadata allocation failure causes a transaction abort.
1925 *
1926 * However, relocations happen into the space_info's unused space, therefore
1927 * automatic reclaim must also back off as that space runs low. There is no
1928 * value in doing trivial "relocations" of re-writing the same block group
1929 * into a fresh one.
1930 *
1931 * Furthermore, we want to avoid doing too much reclaim even if there are good
1932 * candidates. This is because the allocator is pretty good at filling up the
1933 * holes with writes. So we want to do just enough reclaim to try and stay
1934 * safe from running out of unallocated space but not be wasteful about it.
1935 *
1936 * Therefore, the dynamic reclaim threshold is calculated as follows:
1937 * - calculate a target unallocated amount of 5 block group sized chunks
1938 * - ratchet up the intensity of reclaim depending on how far we are from
1939 * that target by using a formula of unalloc / target to set the threshold.
1940 *
1941 * Typically with 10 block groups as the target, the discrete values this comes
1942 * out to are 0, 10, 20, ... , 80, 90, and 99.
1943 */
1944static int calc_dynamic_reclaim_threshold(const struct btrfs_space_info *space_info)
1945{
1946 struct btrfs_fs_info *fs_info = space_info->fs_info;
1947 u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
1948 u64 target = calc_unalloc_target(fs_info);
1949 u64 alloc = space_info->total_bytes;
1950 u64 used = btrfs_space_info_used(space_info, false);
1951 u64 unused = alloc - used;
1952 u64 want = target > unalloc ? target - unalloc : 0;
1953 u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
1954
1955 /* If we have no unused space, don't bother, it won't work anyway. */
1956 if (unused < data_chunk_size)
1957 return 0;
1958
1959 /* Cast to int is OK because want <= target. */
1960 return calc_pct_ratio(want, target);
1961}
1962
1963int btrfs_calc_reclaim_threshold(const struct btrfs_space_info *space_info)
1964{
1965 lockdep_assert_held(&space_info->lock);
1966
1967 if (READ_ONCE(space_info->dynamic_reclaim))
1968 return calc_dynamic_reclaim_threshold(space_info);
1969 return READ_ONCE(space_info->bg_reclaim_threshold);
1970}
1971
1972/*
1973 * Under "urgent" reclaim, we will reclaim even fresh block groups that have
1974 * recently seen successful allocations, as we are desperate to reclaim
1975 * whatever we can to avoid ENOSPC in a transaction leading to a readonly fs.
1976 */
1977static bool is_reclaim_urgent(struct btrfs_space_info *space_info)
1978{
1979 struct btrfs_fs_info *fs_info = space_info->fs_info;
1980 u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
1981 u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
1982
1983 return unalloc < data_chunk_size;
1984}
1985
1986static void do_reclaim_sweep(struct btrfs_space_info *space_info, int raid)
1987{
1988 struct btrfs_block_group *bg;
1989 int thresh_pct;
1990 bool try_again = true;
1991 bool urgent;
1992
1993 spin_lock(&space_info->lock);
1994 urgent = is_reclaim_urgent(space_info);
1995 thresh_pct = btrfs_calc_reclaim_threshold(space_info);
1996 spin_unlock(&space_info->lock);
1997
1998 down_read(&space_info->groups_sem);
1999again:
2000 list_for_each_entry(bg, &space_info->block_groups[raid], list) {
2001 u64 thresh;
2002 bool reclaim = false;
2003
2004 btrfs_get_block_group(bg);
2005 spin_lock(&bg->lock);
2006 thresh = mult_perc(bg->length, thresh_pct);
2007 if (bg->used < thresh && bg->reclaim_mark) {
2008 try_again = false;
2009 reclaim = true;
2010 }
2011 bg->reclaim_mark++;
2012 spin_unlock(&bg->lock);
2013 if (reclaim)
2014 btrfs_mark_bg_to_reclaim(bg);
2015 btrfs_put_block_group(bg);
2016 }
2017
2018 /*
2019 * In situations where we are very motivated to reclaim (low unalloc)
2020 * use two passes to make the reclaim mark check best effort.
2021 *
2022 * If we have any staler groups, we don't touch the fresher ones, but if we
2023 * really need a block group, do take a fresh one.
2024 */
2025 if (try_again && urgent) {
2026 try_again = false;
2027 goto again;
2028 }
2029
2030 up_read(&space_info->groups_sem);
2031}
2032
2033void btrfs_space_info_update_reclaimable(struct btrfs_space_info *space_info, s64 bytes)
2034{
2035 u64 chunk_sz = calc_effective_data_chunk_size(space_info->fs_info);
2036
2037 lockdep_assert_held(&space_info->lock);
2038 space_info->reclaimable_bytes += bytes;
2039
2040 if (space_info->reclaimable_bytes >= chunk_sz)
2041 btrfs_set_periodic_reclaim_ready(space_info, true);
2042}
2043
2044void btrfs_set_periodic_reclaim_ready(struct btrfs_space_info *space_info, bool ready)
2045{
2046 lockdep_assert_held(&space_info->lock);
2047 if (!READ_ONCE(space_info->periodic_reclaim))
2048 return;
2049 if (ready != space_info->periodic_reclaim_ready) {
2050 space_info->periodic_reclaim_ready = ready;
2051 if (!ready)
2052 space_info->reclaimable_bytes = 0;
2053 }
2054}
2055
2056bool btrfs_should_periodic_reclaim(struct btrfs_space_info *space_info)
2057{
2058 bool ret;
2059
2060 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
2061 return false;
2062 if (!READ_ONCE(space_info->periodic_reclaim))
2063 return false;
2064
2065 spin_lock(&space_info->lock);
2066 ret = space_info->periodic_reclaim_ready;
2067 btrfs_set_periodic_reclaim_ready(space_info, false);
2068 spin_unlock(&space_info->lock);
2069
2070 return ret;
2071}
2072
2073void btrfs_reclaim_sweep(const struct btrfs_fs_info *fs_info)
2074{
2075 int raid;
2076 struct btrfs_space_info *space_info;
2077
2078 list_for_each_entry(space_info, &fs_info->space_info, list) {
2079 if (!btrfs_should_periodic_reclaim(space_info))
2080 continue;
2081 for (raid = 0; raid < BTRFS_NR_RAID_TYPES; raid++)
2082 do_reclaim_sweep(space_info, raid);
2083 }
2084}