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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 * This will commit the transaction. Historically we had a lot of logic
137 * surrounding whether or not we'd commit the transaction, but this waits born
138 * out of a pre-tickets era where we could end up committing the transaction
139 * thousands of times in a row without making progress. Now thanks to our
140 * ticketing system we know if we're not making progress and can error
141 * everybody out after a few commits rather than burning the disk hoping for
142 * a different answer.
143 *
144 * OVERCOMMIT
145 *
146 * Because we hold so many reservations for metadata we will allow you to
147 * reserve more space than is currently free in the currently allocate
148 * metadata space. This only happens with metadata, data does not allow
149 * overcommitting.
150 *
151 * You can see the current logic for when we allow overcommit in
152 * btrfs_can_overcommit(), but it only applies to unallocated space. If there
153 * is no unallocated space to be had, all reservations are kept within the
154 * free space in the allocated metadata chunks.
155 *
156 * Because of overcommitting, you generally want to use the
157 * btrfs_can_overcommit() logic for metadata allocations, as it does the right
158 * thing with or without extra unallocated space.
159 */
160
161u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
162 bool may_use_included)
163{
164 ASSERT(s_info);
165 return s_info->bytes_used + s_info->bytes_reserved +
166 s_info->bytes_pinned + s_info->bytes_readonly +
167 s_info->bytes_zone_unusable +
168 (may_use_included ? s_info->bytes_may_use : 0);
169}
170
171/*
172 * after adding space to the filesystem, we need to clear the full flags
173 * on all the space infos.
174 */
175void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
176{
177 struct list_head *head = &info->space_info;
178 struct btrfs_space_info *found;
179
180 list_for_each_entry(found, head, list)
181 found->full = 0;
182}
183
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 for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
196 INIT_LIST_HEAD(&space_info->block_groups[i]);
197 init_rwsem(&space_info->groups_sem);
198 spin_lock_init(&space_info->lock);
199 space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
200 space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
201 INIT_LIST_HEAD(&space_info->ro_bgs);
202 INIT_LIST_HEAD(&space_info->tickets);
203 INIT_LIST_HEAD(&space_info->priority_tickets);
204 space_info->clamp = 1;
205
206 ret = btrfs_sysfs_add_space_info_type(info, space_info);
207 if (ret)
208 return ret;
209
210 list_add(&space_info->list, &info->space_info);
211 if (flags & BTRFS_BLOCK_GROUP_DATA)
212 info->data_sinfo = space_info;
213
214 return ret;
215}
216
217int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
218{
219 struct btrfs_super_block *disk_super;
220 u64 features;
221 u64 flags;
222 int mixed = 0;
223 int ret;
224
225 disk_super = fs_info->super_copy;
226 if (!btrfs_super_root(disk_super))
227 return -EINVAL;
228
229 features = btrfs_super_incompat_flags(disk_super);
230 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
231 mixed = 1;
232
233 flags = BTRFS_BLOCK_GROUP_SYSTEM;
234 ret = create_space_info(fs_info, flags);
235 if (ret)
236 goto out;
237
238 if (mixed) {
239 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
240 ret = create_space_info(fs_info, flags);
241 } else {
242 flags = BTRFS_BLOCK_GROUP_METADATA;
243 ret = create_space_info(fs_info, flags);
244 if (ret)
245 goto out;
246
247 flags = BTRFS_BLOCK_GROUP_DATA;
248 ret = create_space_info(fs_info, flags);
249 }
250out:
251 return ret;
252}
253
254void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
255 u64 total_bytes, u64 bytes_used,
256 u64 bytes_readonly, u64 bytes_zone_unusable,
257 struct btrfs_space_info **space_info)
258{
259 struct btrfs_space_info *found;
260 int factor;
261
262 factor = btrfs_bg_type_to_factor(flags);
263
264 found = btrfs_find_space_info(info, flags);
265 ASSERT(found);
266 spin_lock(&found->lock);
267 found->total_bytes += total_bytes;
268 found->disk_total += total_bytes * factor;
269 found->bytes_used += bytes_used;
270 found->disk_used += bytes_used * factor;
271 found->bytes_readonly += bytes_readonly;
272 found->bytes_zone_unusable += bytes_zone_unusable;
273 if (total_bytes > 0)
274 found->full = 0;
275 btrfs_try_granting_tickets(info, found);
276 spin_unlock(&found->lock);
277 *space_info = found;
278}
279
280struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
281 u64 flags)
282{
283 struct list_head *head = &info->space_info;
284 struct btrfs_space_info *found;
285
286 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
287
288 list_for_each_entry(found, head, list) {
289 if (found->flags & flags)
290 return found;
291 }
292 return NULL;
293}
294
295static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
296 struct btrfs_space_info *space_info,
297 enum btrfs_reserve_flush_enum flush)
298{
299 u64 profile;
300 u64 avail;
301 int factor;
302
303 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
304 profile = btrfs_system_alloc_profile(fs_info);
305 else
306 profile = btrfs_metadata_alloc_profile(fs_info);
307
308 avail = atomic64_read(&fs_info->free_chunk_space);
309
310 /*
311 * If we have dup, raid1 or raid10 then only half of the free
312 * space is actually usable. For raid56, the space info used
313 * doesn't include the parity drive, so we don't have to
314 * change the math
315 */
316 factor = btrfs_bg_type_to_factor(profile);
317 avail = div_u64(avail, factor);
318
319 /*
320 * If we aren't flushing all things, let us overcommit up to
321 * 1/2th of the space. If we can flush, don't let us overcommit
322 * too much, let it overcommit up to 1/8 of the space.
323 */
324 if (flush == BTRFS_RESERVE_FLUSH_ALL)
325 avail >>= 3;
326 else
327 avail >>= 1;
328 return avail;
329}
330
331int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
332 struct btrfs_space_info *space_info, u64 bytes,
333 enum btrfs_reserve_flush_enum flush)
334{
335 u64 avail;
336 u64 used;
337
338 /* Don't overcommit when in mixed mode */
339 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
340 return 0;
341
342 used = btrfs_space_info_used(space_info, true);
343 avail = calc_available_free_space(fs_info, space_info, flush);
344
345 if (used + bytes < space_info->total_bytes + avail)
346 return 1;
347 return 0;
348}
349
350static void remove_ticket(struct btrfs_space_info *space_info,
351 struct reserve_ticket *ticket)
352{
353 if (!list_empty(&ticket->list)) {
354 list_del_init(&ticket->list);
355 ASSERT(space_info->reclaim_size >= ticket->bytes);
356 space_info->reclaim_size -= ticket->bytes;
357 }
358}
359
360/*
361 * This is for space we already have accounted in space_info->bytes_may_use, so
362 * basically when we're returning space from block_rsv's.
363 */
364void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
365 struct btrfs_space_info *space_info)
366{
367 struct list_head *head;
368 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
369
370 lockdep_assert_held(&space_info->lock);
371
372 head = &space_info->priority_tickets;
373again:
374 while (!list_empty(head)) {
375 struct reserve_ticket *ticket;
376 u64 used = btrfs_space_info_used(space_info, true);
377
378 ticket = list_first_entry(head, struct reserve_ticket, list);
379
380 /* Check and see if our ticket can be satisfied now. */
381 if ((used + ticket->bytes <= space_info->total_bytes) ||
382 btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
383 flush)) {
384 btrfs_space_info_update_bytes_may_use(fs_info,
385 space_info,
386 ticket->bytes);
387 remove_ticket(space_info, ticket);
388 ticket->bytes = 0;
389 space_info->tickets_id++;
390 wake_up(&ticket->wait);
391 } else {
392 break;
393 }
394 }
395
396 if (head == &space_info->priority_tickets) {
397 head = &space_info->tickets;
398 flush = BTRFS_RESERVE_FLUSH_ALL;
399 goto again;
400 }
401}
402
403#define DUMP_BLOCK_RSV(fs_info, rsv_name) \
404do { \
405 struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \
406 spin_lock(&__rsv->lock); \
407 btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \
408 __rsv->size, __rsv->reserved); \
409 spin_unlock(&__rsv->lock); \
410} while (0)
411
412static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
413 struct btrfs_space_info *info)
414{
415 lockdep_assert_held(&info->lock);
416
417 /* The free space could be negative in case of overcommit */
418 btrfs_info(fs_info, "space_info %llu has %lld free, is %sfull",
419 info->flags,
420 (s64)(info->total_bytes - btrfs_space_info_used(info, true)),
421 info->full ? "" : "not ");
422 btrfs_info(fs_info,
423 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
424 info->total_bytes, info->bytes_used, info->bytes_pinned,
425 info->bytes_reserved, info->bytes_may_use,
426 info->bytes_readonly, info->bytes_zone_unusable);
427
428 DUMP_BLOCK_RSV(fs_info, global_block_rsv);
429 DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
430 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
431 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
432 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
433
434}
435
436void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
437 struct btrfs_space_info *info, u64 bytes,
438 int dump_block_groups)
439{
440 struct btrfs_block_group *cache;
441 int index = 0;
442
443 spin_lock(&info->lock);
444 __btrfs_dump_space_info(fs_info, info);
445 spin_unlock(&info->lock);
446
447 if (!dump_block_groups)
448 return;
449
450 down_read(&info->groups_sem);
451again:
452 list_for_each_entry(cache, &info->block_groups[index], list) {
453 spin_lock(&cache->lock);
454 btrfs_info(fs_info,
455 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu zone_unusable %s",
456 cache->start, cache->length, cache->used, cache->pinned,
457 cache->reserved, cache->zone_unusable,
458 cache->ro ? "[readonly]" : "");
459 spin_unlock(&cache->lock);
460 btrfs_dump_free_space(cache, bytes);
461 }
462 if (++index < BTRFS_NR_RAID_TYPES)
463 goto again;
464 up_read(&info->groups_sem);
465}
466
467static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
468 u64 to_reclaim)
469{
470 u64 bytes;
471 u64 nr;
472
473 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
474 nr = div64_u64(to_reclaim, bytes);
475 if (!nr)
476 nr = 1;
477 return nr;
478}
479
480#define EXTENT_SIZE_PER_ITEM SZ_256K
481
482/*
483 * shrink metadata reservation for delalloc
484 */
485static void shrink_delalloc(struct btrfs_fs_info *fs_info,
486 struct btrfs_space_info *space_info,
487 u64 to_reclaim, bool wait_ordered,
488 bool for_preempt)
489{
490 struct btrfs_trans_handle *trans;
491 u64 delalloc_bytes;
492 u64 ordered_bytes;
493 u64 items;
494 long time_left;
495 int loops;
496
497 delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
498 ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
499 if (delalloc_bytes == 0 && ordered_bytes == 0)
500 return;
501
502 /* Calc the number of the pages we need flush for space reservation */
503 if (to_reclaim == U64_MAX) {
504 items = U64_MAX;
505 } else {
506 /*
507 * to_reclaim is set to however much metadata we need to
508 * reclaim, but reclaiming that much data doesn't really track
509 * exactly. What we really want to do is reclaim full inode's
510 * worth of reservations, however that's not available to us
511 * here. We will take a fraction of the delalloc bytes for our
512 * flushing loops and hope for the best. Delalloc will expand
513 * the amount we write to cover an entire dirty extent, which
514 * will reclaim the metadata reservation for that range. If
515 * it's not enough subsequent flush stages will be more
516 * aggressive.
517 */
518 to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
519 items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
520 }
521
522 trans = (struct btrfs_trans_handle *)current->journal_info;
523
524 /*
525 * If we are doing more ordered than delalloc we need to just wait on
526 * ordered extents, otherwise we'll waste time trying to flush delalloc
527 * that likely won't give us the space back we need.
528 */
529 if (ordered_bytes > delalloc_bytes && !for_preempt)
530 wait_ordered = true;
531
532 loops = 0;
533 while ((delalloc_bytes || ordered_bytes) && loops < 3) {
534 u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
535 long nr_pages = min_t(u64, temp, LONG_MAX);
536 int async_pages;
537
538 btrfs_start_delalloc_roots(fs_info, nr_pages, true);
539
540 /*
541 * We need to make sure any outstanding async pages are now
542 * processed before we continue. This is because things like
543 * sync_inode() try to be smart and skip writing if the inode is
544 * marked clean. We don't use filemap_fwrite for flushing
545 * because we want to control how many pages we write out at a
546 * time, thus this is the only safe way to make sure we've
547 * waited for outstanding compressed workers to have started
548 * their jobs and thus have ordered extents set up properly.
549 *
550 * This exists because we do not want to wait for each
551 * individual inode to finish its async work, we simply want to
552 * start the IO on everybody, and then come back here and wait
553 * for all of the async work to catch up. Once we're done with
554 * that we know we'll have ordered extents for everything and we
555 * can decide if we wait for that or not.
556 *
557 * If we choose to replace this in the future, make absolutely
558 * sure that the proper waiting is being done in the async case,
559 * as there have been bugs in that area before.
560 */
561 async_pages = atomic_read(&fs_info->async_delalloc_pages);
562 if (!async_pages)
563 goto skip_async;
564
565 /*
566 * We don't want to wait forever, if we wrote less pages in this
567 * loop than we have outstanding, only wait for that number of
568 * pages, otherwise we can wait for all async pages to finish
569 * before continuing.
570 */
571 if (async_pages > nr_pages)
572 async_pages -= nr_pages;
573 else
574 async_pages = 0;
575 wait_event(fs_info->async_submit_wait,
576 atomic_read(&fs_info->async_delalloc_pages) <=
577 async_pages);
578skip_async:
579 loops++;
580 if (wait_ordered && !trans) {
581 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
582 } else {
583 time_left = schedule_timeout_killable(1);
584 if (time_left)
585 break;
586 }
587
588 /*
589 * If we are for preemption we just want a one-shot of delalloc
590 * flushing so we can stop flushing if we decide we don't need
591 * to anymore.
592 */
593 if (for_preempt)
594 break;
595
596 spin_lock(&space_info->lock);
597 if (list_empty(&space_info->tickets) &&
598 list_empty(&space_info->priority_tickets)) {
599 spin_unlock(&space_info->lock);
600 break;
601 }
602 spin_unlock(&space_info->lock);
603
604 delalloc_bytes = percpu_counter_sum_positive(
605 &fs_info->delalloc_bytes);
606 ordered_bytes = percpu_counter_sum_positive(
607 &fs_info->ordered_bytes);
608 }
609}
610
611/*
612 * Try to flush some data based on policy set by @state. This is only advisory
613 * and may fail for various reasons. The caller is supposed to examine the
614 * state of @space_info to detect the outcome.
615 */
616static void flush_space(struct btrfs_fs_info *fs_info,
617 struct btrfs_space_info *space_info, u64 num_bytes,
618 enum btrfs_flush_state state, bool for_preempt)
619{
620 struct btrfs_root *root = fs_info->extent_root;
621 struct btrfs_trans_handle *trans;
622 int nr;
623 int ret = 0;
624
625 switch (state) {
626 case FLUSH_DELAYED_ITEMS_NR:
627 case FLUSH_DELAYED_ITEMS:
628 if (state == FLUSH_DELAYED_ITEMS_NR)
629 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
630 else
631 nr = -1;
632
633 trans = btrfs_join_transaction(root);
634 if (IS_ERR(trans)) {
635 ret = PTR_ERR(trans);
636 break;
637 }
638 ret = btrfs_run_delayed_items_nr(trans, nr);
639 btrfs_end_transaction(trans);
640 break;
641 case FLUSH_DELALLOC:
642 case FLUSH_DELALLOC_WAIT:
643 case FLUSH_DELALLOC_FULL:
644 if (state == FLUSH_DELALLOC_FULL)
645 num_bytes = U64_MAX;
646 shrink_delalloc(fs_info, space_info, num_bytes,
647 state != FLUSH_DELALLOC, for_preempt);
648 break;
649 case FLUSH_DELAYED_REFS_NR:
650 case FLUSH_DELAYED_REFS:
651 trans = btrfs_join_transaction(root);
652 if (IS_ERR(trans)) {
653 ret = PTR_ERR(trans);
654 break;
655 }
656 if (state == FLUSH_DELAYED_REFS_NR)
657 nr = calc_reclaim_items_nr(fs_info, num_bytes);
658 else
659 nr = 0;
660 btrfs_run_delayed_refs(trans, nr);
661 btrfs_end_transaction(trans);
662 break;
663 case ALLOC_CHUNK:
664 case ALLOC_CHUNK_FORCE:
665 trans = btrfs_join_transaction(root);
666 if (IS_ERR(trans)) {
667 ret = PTR_ERR(trans);
668 break;
669 }
670 ret = btrfs_chunk_alloc(trans,
671 btrfs_get_alloc_profile(fs_info, space_info->flags),
672 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
673 CHUNK_ALLOC_FORCE);
674 btrfs_end_transaction(trans);
675 if (ret > 0 || ret == -ENOSPC)
676 ret = 0;
677 break;
678 case RUN_DELAYED_IPUTS:
679 /*
680 * If we have pending delayed iputs then we could free up a
681 * bunch of pinned space, so make sure we run the iputs before
682 * we do our pinned bytes check below.
683 */
684 btrfs_run_delayed_iputs(fs_info);
685 btrfs_wait_on_delayed_iputs(fs_info);
686 break;
687 case COMMIT_TRANS:
688 ASSERT(current->journal_info == NULL);
689 trans = btrfs_join_transaction(root);
690 if (IS_ERR(trans)) {
691 ret = PTR_ERR(trans);
692 break;
693 }
694 ret = btrfs_commit_transaction(trans);
695 break;
696 default:
697 ret = -ENOSPC;
698 break;
699 }
700
701 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
702 ret, for_preempt);
703 return;
704}
705
706static inline u64
707btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
708 struct btrfs_space_info *space_info)
709{
710 u64 used;
711 u64 avail;
712 u64 to_reclaim = space_info->reclaim_size;
713
714 lockdep_assert_held(&space_info->lock);
715
716 avail = calc_available_free_space(fs_info, space_info,
717 BTRFS_RESERVE_FLUSH_ALL);
718 used = btrfs_space_info_used(space_info, true);
719
720 /*
721 * We may be flushing because suddenly we have less space than we had
722 * before, and now we're well over-committed based on our current free
723 * space. If that's the case add in our overage so we make sure to put
724 * appropriate pressure on the flushing state machine.
725 */
726 if (space_info->total_bytes + avail < used)
727 to_reclaim += used - (space_info->total_bytes + avail);
728
729 return to_reclaim;
730}
731
732static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
733 struct btrfs_space_info *space_info)
734{
735 u64 global_rsv_size = fs_info->global_block_rsv.reserved;
736 u64 ordered, delalloc;
737 u64 thresh = div_factor_fine(space_info->total_bytes, 90);
738 u64 used;
739
740 /* If we're just plain full then async reclaim just slows us down. */
741 if ((space_info->bytes_used + space_info->bytes_reserved +
742 global_rsv_size) >= thresh)
743 return false;
744
745 used = space_info->bytes_may_use + space_info->bytes_pinned;
746
747 /* The total flushable belongs to the global rsv, don't flush. */
748 if (global_rsv_size >= used)
749 return false;
750
751 /*
752 * 128MiB is 1/4 of the maximum global rsv size. If we have less than
753 * that devoted to other reservations then there's no sense in flushing,
754 * we don't have a lot of things that need flushing.
755 */
756 if (used - global_rsv_size <= SZ_128M)
757 return false;
758
759 /*
760 * We have tickets queued, bail so we don't compete with the async
761 * flushers.
762 */
763 if (space_info->reclaim_size)
764 return false;
765
766 /*
767 * If we have over half of the free space occupied by reservations or
768 * pinned then we want to start flushing.
769 *
770 * We do not do the traditional thing here, which is to say
771 *
772 * if (used >= ((total_bytes + avail) / 2))
773 * return 1;
774 *
775 * because this doesn't quite work how we want. If we had more than 50%
776 * of the space_info used by bytes_used and we had 0 available we'd just
777 * constantly run the background flusher. Instead we want it to kick in
778 * if our reclaimable space exceeds our clamped free space.
779 *
780 * Our clamping range is 2^1 -> 2^8. Practically speaking that means
781 * the following:
782 *
783 * Amount of RAM Minimum threshold Maximum threshold
784 *
785 * 256GiB 1GiB 128GiB
786 * 128GiB 512MiB 64GiB
787 * 64GiB 256MiB 32GiB
788 * 32GiB 128MiB 16GiB
789 * 16GiB 64MiB 8GiB
790 *
791 * These are the range our thresholds will fall in, corresponding to how
792 * much delalloc we need for the background flusher to kick in.
793 */
794
795 thresh = calc_available_free_space(fs_info, space_info,
796 BTRFS_RESERVE_FLUSH_ALL);
797 used = space_info->bytes_used + space_info->bytes_reserved +
798 space_info->bytes_readonly + global_rsv_size;
799 if (used < space_info->total_bytes)
800 thresh += space_info->total_bytes - used;
801 thresh >>= space_info->clamp;
802
803 used = space_info->bytes_pinned;
804
805 /*
806 * If we have more ordered bytes than delalloc bytes then we're either
807 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
808 * around. Preemptive flushing is only useful in that it can free up
809 * space before tickets need to wait for things to finish. In the case
810 * of ordered extents, preemptively waiting on ordered extents gets us
811 * nothing, if our reservations are tied up in ordered extents we'll
812 * simply have to slow down writers by forcing them to wait on ordered
813 * extents.
814 *
815 * In the case that ordered is larger than delalloc, only include the
816 * block reserves that we would actually be able to directly reclaim
817 * from. In this case if we're heavy on metadata operations this will
818 * clearly be heavy enough to warrant preemptive flushing. In the case
819 * of heavy DIO or ordered reservations, preemptive flushing will just
820 * waste time and cause us to slow down.
821 *
822 * We want to make sure we truly are maxed out on ordered however, so
823 * cut ordered in half, and if it's still higher than delalloc then we
824 * can keep flushing. This is to avoid the case where we start
825 * flushing, and now delalloc == ordered and we stop preemptively
826 * flushing when we could still have several gigs of delalloc to flush.
827 */
828 ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
829 delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
830 if (ordered >= delalloc)
831 used += fs_info->delayed_refs_rsv.reserved +
832 fs_info->delayed_block_rsv.reserved;
833 else
834 used += space_info->bytes_may_use - global_rsv_size;
835
836 return (used >= thresh && !btrfs_fs_closing(fs_info) &&
837 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
838}
839
840static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
841 struct btrfs_space_info *space_info,
842 struct reserve_ticket *ticket)
843{
844 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
845 u64 min_bytes;
846
847 if (global_rsv->space_info != space_info)
848 return false;
849
850 spin_lock(&global_rsv->lock);
851 min_bytes = div_factor(global_rsv->size, 1);
852 if (global_rsv->reserved < min_bytes + ticket->bytes) {
853 spin_unlock(&global_rsv->lock);
854 return false;
855 }
856 global_rsv->reserved -= ticket->bytes;
857 remove_ticket(space_info, ticket);
858 ticket->bytes = 0;
859 wake_up(&ticket->wait);
860 space_info->tickets_id++;
861 if (global_rsv->reserved < global_rsv->size)
862 global_rsv->full = 0;
863 spin_unlock(&global_rsv->lock);
864
865 return true;
866}
867
868/*
869 * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets
870 * @fs_info - fs_info for this fs
871 * @space_info - the space info we were flushing
872 *
873 * We call this when we've exhausted our flushing ability and haven't made
874 * progress in satisfying tickets. The reservation code handles tickets in
875 * order, so if there is a large ticket first and then smaller ones we could
876 * very well satisfy the smaller tickets. This will attempt to wake up any
877 * tickets in the list to catch this case.
878 *
879 * This function returns true if it was able to make progress by clearing out
880 * other tickets, or if it stumbles across a ticket that was smaller than the
881 * first ticket.
882 */
883static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
884 struct btrfs_space_info *space_info)
885{
886 struct reserve_ticket *ticket;
887 u64 tickets_id = space_info->tickets_id;
888
889 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
890 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
891 __btrfs_dump_space_info(fs_info, space_info);
892 }
893
894 while (!list_empty(&space_info->tickets) &&
895 tickets_id == space_info->tickets_id) {
896 ticket = list_first_entry(&space_info->tickets,
897 struct reserve_ticket, list);
898
899 if (ticket->steal &&
900 steal_from_global_rsv(fs_info, space_info, ticket))
901 return true;
902
903 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
904 btrfs_info(fs_info, "failing ticket with %llu bytes",
905 ticket->bytes);
906
907 remove_ticket(space_info, ticket);
908 ticket->error = -ENOSPC;
909 wake_up(&ticket->wait);
910
911 /*
912 * We're just throwing tickets away, so more flushing may not
913 * trip over btrfs_try_granting_tickets, so we need to call it
914 * here to see if we can make progress with the next ticket in
915 * the list.
916 */
917 btrfs_try_granting_tickets(fs_info, space_info);
918 }
919 return (tickets_id != space_info->tickets_id);
920}
921
922/*
923 * This is for normal flushers, we can wait all goddamned day if we want to. We
924 * will loop and continuously try to flush as long as we are making progress.
925 * We count progress as clearing off tickets each time we have to loop.
926 */
927static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
928{
929 struct btrfs_fs_info *fs_info;
930 struct btrfs_space_info *space_info;
931 u64 to_reclaim;
932 enum btrfs_flush_state flush_state;
933 int commit_cycles = 0;
934 u64 last_tickets_id;
935
936 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
937 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
938
939 spin_lock(&space_info->lock);
940 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
941 if (!to_reclaim) {
942 space_info->flush = 0;
943 spin_unlock(&space_info->lock);
944 return;
945 }
946 last_tickets_id = space_info->tickets_id;
947 spin_unlock(&space_info->lock);
948
949 flush_state = FLUSH_DELAYED_ITEMS_NR;
950 do {
951 flush_space(fs_info, space_info, to_reclaim, flush_state, false);
952 spin_lock(&space_info->lock);
953 if (list_empty(&space_info->tickets)) {
954 space_info->flush = 0;
955 spin_unlock(&space_info->lock);
956 return;
957 }
958 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
959 space_info);
960 if (last_tickets_id == space_info->tickets_id) {
961 flush_state++;
962 } else {
963 last_tickets_id = space_info->tickets_id;
964 flush_state = FLUSH_DELAYED_ITEMS_NR;
965 if (commit_cycles)
966 commit_cycles--;
967 }
968
969 /*
970 * We do not want to empty the system of delalloc unless we're
971 * under heavy pressure, so allow one trip through the flushing
972 * logic before we start doing a FLUSH_DELALLOC_FULL.
973 */
974 if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
975 flush_state++;
976
977 /*
978 * We don't want to force a chunk allocation until we've tried
979 * pretty hard to reclaim space. Think of the case where we
980 * freed up a bunch of space and so have a lot of pinned space
981 * to reclaim. We would rather use that than possibly create a
982 * underutilized metadata chunk. So if this is our first run
983 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
984 * commit the transaction. If nothing has changed the next go
985 * around then we can force a chunk allocation.
986 */
987 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
988 flush_state++;
989
990 if (flush_state > COMMIT_TRANS) {
991 commit_cycles++;
992 if (commit_cycles > 2) {
993 if (maybe_fail_all_tickets(fs_info, space_info)) {
994 flush_state = FLUSH_DELAYED_ITEMS_NR;
995 commit_cycles--;
996 } else {
997 space_info->flush = 0;
998 }
999 } else {
1000 flush_state = FLUSH_DELAYED_ITEMS_NR;
1001 }
1002 }
1003 spin_unlock(&space_info->lock);
1004 } while (flush_state <= COMMIT_TRANS);
1005}
1006
1007/*
1008 * This handles pre-flushing of metadata space before we get to the point that
1009 * we need to start blocking threads on tickets. The logic here is different
1010 * from the other flush paths because it doesn't rely on tickets to tell us how
1011 * much we need to flush, instead it attempts to keep us below the 80% full
1012 * watermark of space by flushing whichever reservation pool is currently the
1013 * largest.
1014 */
1015static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
1016{
1017 struct btrfs_fs_info *fs_info;
1018 struct btrfs_space_info *space_info;
1019 struct btrfs_block_rsv *delayed_block_rsv;
1020 struct btrfs_block_rsv *delayed_refs_rsv;
1021 struct btrfs_block_rsv *global_rsv;
1022 struct btrfs_block_rsv *trans_rsv;
1023 int loops = 0;
1024
1025 fs_info = container_of(work, struct btrfs_fs_info,
1026 preempt_reclaim_work);
1027 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1028 delayed_block_rsv = &fs_info->delayed_block_rsv;
1029 delayed_refs_rsv = &fs_info->delayed_refs_rsv;
1030 global_rsv = &fs_info->global_block_rsv;
1031 trans_rsv = &fs_info->trans_block_rsv;
1032
1033 spin_lock(&space_info->lock);
1034 while (need_preemptive_reclaim(fs_info, space_info)) {
1035 enum btrfs_flush_state flush;
1036 u64 delalloc_size = 0;
1037 u64 to_reclaim, block_rsv_size;
1038 u64 global_rsv_size = global_rsv->reserved;
1039
1040 loops++;
1041
1042 /*
1043 * We don't have a precise counter for the metadata being
1044 * reserved for delalloc, so we'll approximate it by subtracting
1045 * out the block rsv's space from the bytes_may_use. If that
1046 * amount is higher than the individual reserves, then we can
1047 * assume it's tied up in delalloc reservations.
1048 */
1049 block_rsv_size = global_rsv_size +
1050 delayed_block_rsv->reserved +
1051 delayed_refs_rsv->reserved +
1052 trans_rsv->reserved;
1053 if (block_rsv_size < space_info->bytes_may_use)
1054 delalloc_size = space_info->bytes_may_use - block_rsv_size;
1055 spin_unlock(&space_info->lock);
1056
1057 /*
1058 * We don't want to include the global_rsv in our calculation,
1059 * because that's space we can't touch. Subtract it from the
1060 * block_rsv_size for the next checks.
1061 */
1062 block_rsv_size -= global_rsv_size;
1063
1064 /*
1065 * We really want to avoid flushing delalloc too much, as it
1066 * could result in poor allocation patterns, so only flush it if
1067 * it's larger than the rest of the pools combined.
1068 */
1069 if (delalloc_size > block_rsv_size) {
1070 to_reclaim = delalloc_size;
1071 flush = FLUSH_DELALLOC;
1072 } else if (space_info->bytes_pinned >
1073 (delayed_block_rsv->reserved +
1074 delayed_refs_rsv->reserved)) {
1075 to_reclaim = space_info->bytes_pinned;
1076 flush = COMMIT_TRANS;
1077 } else if (delayed_block_rsv->reserved >
1078 delayed_refs_rsv->reserved) {
1079 to_reclaim = delayed_block_rsv->reserved;
1080 flush = FLUSH_DELAYED_ITEMS_NR;
1081 } else {
1082 to_reclaim = delayed_refs_rsv->reserved;
1083 flush = FLUSH_DELAYED_REFS_NR;
1084 }
1085
1086 /*
1087 * We don't want to reclaim everything, just a portion, so scale
1088 * down the to_reclaim by 1/4. If it takes us down to 0,
1089 * reclaim 1 items worth.
1090 */
1091 to_reclaim >>= 2;
1092 if (!to_reclaim)
1093 to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1094 flush_space(fs_info, space_info, to_reclaim, flush, true);
1095 cond_resched();
1096 spin_lock(&space_info->lock);
1097 }
1098
1099 /* We only went through once, back off our clamping. */
1100 if (loops == 1 && !space_info->reclaim_size)
1101 space_info->clamp = max(1, space_info->clamp - 1);
1102 trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1103 spin_unlock(&space_info->lock);
1104}
1105
1106/*
1107 * FLUSH_DELALLOC_WAIT:
1108 * Space is freed from flushing delalloc in one of two ways.
1109 *
1110 * 1) compression is on and we allocate less space than we reserved
1111 * 2) we are overwriting existing space
1112 *
1113 * For #1 that extra space is reclaimed as soon as the delalloc pages are
1114 * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1115 * length to ->bytes_reserved, and subtracts the reserved space from
1116 * ->bytes_may_use.
1117 *
1118 * For #2 this is trickier. Once the ordered extent runs we will drop the
1119 * extent in the range we are overwriting, which creates a delayed ref for
1120 * that freed extent. This however is not reclaimed until the transaction
1121 * commits, thus the next stages.
1122 *
1123 * RUN_DELAYED_IPUTS
1124 * If we are freeing inodes, we want to make sure all delayed iputs have
1125 * completed, because they could have been on an inode with i_nlink == 0, and
1126 * thus have been truncated and freed up space. But again this space is not
1127 * immediately re-usable, it comes in the form of a delayed ref, which must be
1128 * run and then the transaction must be committed.
1129 *
1130 * COMMIT_TRANS
1131 * This is where we reclaim all of the pinned space generated by running the
1132 * iputs
1133 *
1134 * ALLOC_CHUNK_FORCE
1135 * For data we start with alloc chunk force, however we could have been full
1136 * before, and then the transaction commit could have freed new block groups,
1137 * so if we now have space to allocate do the force chunk allocation.
1138 */
1139static const enum btrfs_flush_state data_flush_states[] = {
1140 FLUSH_DELALLOC_FULL,
1141 RUN_DELAYED_IPUTS,
1142 COMMIT_TRANS,
1143 ALLOC_CHUNK_FORCE,
1144};
1145
1146static void btrfs_async_reclaim_data_space(struct work_struct *work)
1147{
1148 struct btrfs_fs_info *fs_info;
1149 struct btrfs_space_info *space_info;
1150 u64 last_tickets_id;
1151 enum btrfs_flush_state flush_state = 0;
1152
1153 fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1154 space_info = fs_info->data_sinfo;
1155
1156 spin_lock(&space_info->lock);
1157 if (list_empty(&space_info->tickets)) {
1158 space_info->flush = 0;
1159 spin_unlock(&space_info->lock);
1160 return;
1161 }
1162 last_tickets_id = space_info->tickets_id;
1163 spin_unlock(&space_info->lock);
1164
1165 while (!space_info->full) {
1166 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1167 spin_lock(&space_info->lock);
1168 if (list_empty(&space_info->tickets)) {
1169 space_info->flush = 0;
1170 spin_unlock(&space_info->lock);
1171 return;
1172 }
1173 last_tickets_id = space_info->tickets_id;
1174 spin_unlock(&space_info->lock);
1175 }
1176
1177 while (flush_state < ARRAY_SIZE(data_flush_states)) {
1178 flush_space(fs_info, space_info, U64_MAX,
1179 data_flush_states[flush_state], false);
1180 spin_lock(&space_info->lock);
1181 if (list_empty(&space_info->tickets)) {
1182 space_info->flush = 0;
1183 spin_unlock(&space_info->lock);
1184 return;
1185 }
1186
1187 if (last_tickets_id == space_info->tickets_id) {
1188 flush_state++;
1189 } else {
1190 last_tickets_id = space_info->tickets_id;
1191 flush_state = 0;
1192 }
1193
1194 if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1195 if (space_info->full) {
1196 if (maybe_fail_all_tickets(fs_info, space_info))
1197 flush_state = 0;
1198 else
1199 space_info->flush = 0;
1200 } else {
1201 flush_state = 0;
1202 }
1203 }
1204 spin_unlock(&space_info->lock);
1205 }
1206}
1207
1208void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1209{
1210 INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1211 INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1212 INIT_WORK(&fs_info->preempt_reclaim_work,
1213 btrfs_preempt_reclaim_metadata_space);
1214}
1215
1216static const enum btrfs_flush_state priority_flush_states[] = {
1217 FLUSH_DELAYED_ITEMS_NR,
1218 FLUSH_DELAYED_ITEMS,
1219 ALLOC_CHUNK,
1220};
1221
1222static const enum btrfs_flush_state evict_flush_states[] = {
1223 FLUSH_DELAYED_ITEMS_NR,
1224 FLUSH_DELAYED_ITEMS,
1225 FLUSH_DELAYED_REFS_NR,
1226 FLUSH_DELAYED_REFS,
1227 FLUSH_DELALLOC,
1228 FLUSH_DELALLOC_WAIT,
1229 FLUSH_DELALLOC_FULL,
1230 ALLOC_CHUNK,
1231 COMMIT_TRANS,
1232};
1233
1234static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1235 struct btrfs_space_info *space_info,
1236 struct reserve_ticket *ticket,
1237 const enum btrfs_flush_state *states,
1238 int states_nr)
1239{
1240 u64 to_reclaim;
1241 int flush_state;
1242
1243 spin_lock(&space_info->lock);
1244 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1245 if (!to_reclaim) {
1246 spin_unlock(&space_info->lock);
1247 return;
1248 }
1249 spin_unlock(&space_info->lock);
1250
1251 flush_state = 0;
1252 do {
1253 flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1254 false);
1255 flush_state++;
1256 spin_lock(&space_info->lock);
1257 if (ticket->bytes == 0) {
1258 spin_unlock(&space_info->lock);
1259 return;
1260 }
1261 spin_unlock(&space_info->lock);
1262 } while (flush_state < states_nr);
1263}
1264
1265static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1266 struct btrfs_space_info *space_info,
1267 struct reserve_ticket *ticket)
1268{
1269 while (!space_info->full) {
1270 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1271 spin_lock(&space_info->lock);
1272 if (ticket->bytes == 0) {
1273 spin_unlock(&space_info->lock);
1274 return;
1275 }
1276 spin_unlock(&space_info->lock);
1277 }
1278}
1279
1280static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1281 struct btrfs_space_info *space_info,
1282 struct reserve_ticket *ticket)
1283
1284{
1285 DEFINE_WAIT(wait);
1286 int ret = 0;
1287
1288 spin_lock(&space_info->lock);
1289 while (ticket->bytes > 0 && ticket->error == 0) {
1290 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1291 if (ret) {
1292 /*
1293 * Delete us from the list. After we unlock the space
1294 * info, we don't want the async reclaim job to reserve
1295 * space for this ticket. If that would happen, then the
1296 * ticket's task would not known that space was reserved
1297 * despite getting an error, resulting in a space leak
1298 * (bytes_may_use counter of our space_info).
1299 */
1300 remove_ticket(space_info, ticket);
1301 ticket->error = -EINTR;
1302 break;
1303 }
1304 spin_unlock(&space_info->lock);
1305
1306 schedule();
1307
1308 finish_wait(&ticket->wait, &wait);
1309 spin_lock(&space_info->lock);
1310 }
1311 spin_unlock(&space_info->lock);
1312}
1313
1314/**
1315 * Do the appropriate flushing and waiting for a ticket
1316 *
1317 * @fs_info: the filesystem
1318 * @space_info: space info for the reservation
1319 * @ticket: ticket for the reservation
1320 * @start_ns: timestamp when the reservation started
1321 * @orig_bytes: amount of bytes originally reserved
1322 * @flush: how much we can flush
1323 *
1324 * This does the work of figuring out how to flush for the ticket, waiting for
1325 * the reservation, and returning the appropriate error if there is one.
1326 */
1327static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1328 struct btrfs_space_info *space_info,
1329 struct reserve_ticket *ticket,
1330 u64 start_ns, u64 orig_bytes,
1331 enum btrfs_reserve_flush_enum flush)
1332{
1333 int ret;
1334
1335 switch (flush) {
1336 case BTRFS_RESERVE_FLUSH_DATA:
1337 case BTRFS_RESERVE_FLUSH_ALL:
1338 case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1339 wait_reserve_ticket(fs_info, space_info, ticket);
1340 break;
1341 case BTRFS_RESERVE_FLUSH_LIMIT:
1342 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1343 priority_flush_states,
1344 ARRAY_SIZE(priority_flush_states));
1345 break;
1346 case BTRFS_RESERVE_FLUSH_EVICT:
1347 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1348 evict_flush_states,
1349 ARRAY_SIZE(evict_flush_states));
1350 break;
1351 case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1352 priority_reclaim_data_space(fs_info, space_info, ticket);
1353 break;
1354 default:
1355 ASSERT(0);
1356 break;
1357 }
1358
1359 spin_lock(&space_info->lock);
1360 ret = ticket->error;
1361 if (ticket->bytes || ticket->error) {
1362 /*
1363 * We were a priority ticket, so we need to delete ourselves
1364 * from the list. Because we could have other priority tickets
1365 * behind us that require less space, run
1366 * btrfs_try_granting_tickets() to see if their reservations can
1367 * now be made.
1368 */
1369 if (!list_empty(&ticket->list)) {
1370 remove_ticket(space_info, ticket);
1371 btrfs_try_granting_tickets(fs_info, space_info);
1372 }
1373
1374 if (!ret)
1375 ret = -ENOSPC;
1376 }
1377 spin_unlock(&space_info->lock);
1378 ASSERT(list_empty(&ticket->list));
1379 /*
1380 * Check that we can't have an error set if the reservation succeeded,
1381 * as that would confuse tasks and lead them to error out without
1382 * releasing reserved space (if an error happens the expectation is that
1383 * space wasn't reserved at all).
1384 */
1385 ASSERT(!(ticket->bytes == 0 && ticket->error));
1386 trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1387 start_ns, flush, ticket->error);
1388 return ret;
1389}
1390
1391/*
1392 * This returns true if this flush state will go through the ordinary flushing
1393 * code.
1394 */
1395static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1396{
1397 return (flush == BTRFS_RESERVE_FLUSH_ALL) ||
1398 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1399}
1400
1401static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1402 struct btrfs_space_info *space_info)
1403{
1404 u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1405 u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1406
1407 /*
1408 * If we're heavy on ordered operations then clamping won't help us. We
1409 * need to clamp specifically to keep up with dirty'ing buffered
1410 * writers, because there's not a 1:1 correlation of writing delalloc
1411 * and freeing space, like there is with flushing delayed refs or
1412 * delayed nodes. If we're already more ordered than delalloc then
1413 * we're keeping up, otherwise we aren't and should probably clamp.
1414 */
1415 if (ordered < delalloc)
1416 space_info->clamp = min(space_info->clamp + 1, 8);
1417}
1418
1419/**
1420 * Try to reserve bytes from the block_rsv's space
1421 *
1422 * @fs_info: the filesystem
1423 * @space_info: space info we want to allocate from
1424 * @orig_bytes: number of bytes we want
1425 * @flush: whether or not we can flush to make our reservation
1426 *
1427 * This will reserve orig_bytes number of bytes from the space info associated
1428 * with the block_rsv. If there is not enough space it will make an attempt to
1429 * flush out space to make room. It will do this by flushing delalloc if
1430 * possible or committing the transaction. If flush is 0 then no attempts to
1431 * regain reservations will be made and this will fail if there is not enough
1432 * space already.
1433 */
1434static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1435 struct btrfs_space_info *space_info, u64 orig_bytes,
1436 enum btrfs_reserve_flush_enum flush)
1437{
1438 struct work_struct *async_work;
1439 struct reserve_ticket ticket;
1440 u64 start_ns = 0;
1441 u64 used;
1442 int ret = 0;
1443 bool pending_tickets;
1444
1445 ASSERT(orig_bytes);
1446 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
1447
1448 if (flush == BTRFS_RESERVE_FLUSH_DATA)
1449 async_work = &fs_info->async_data_reclaim_work;
1450 else
1451 async_work = &fs_info->async_reclaim_work;
1452
1453 spin_lock(&space_info->lock);
1454 ret = -ENOSPC;
1455 used = btrfs_space_info_used(space_info, true);
1456
1457 /*
1458 * We don't want NO_FLUSH allocations to jump everybody, they can
1459 * generally handle ENOSPC in a different way, so treat them the same as
1460 * normal flushers when it comes to skipping pending tickets.
1461 */
1462 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1463 pending_tickets = !list_empty(&space_info->tickets) ||
1464 !list_empty(&space_info->priority_tickets);
1465 else
1466 pending_tickets = !list_empty(&space_info->priority_tickets);
1467
1468 /*
1469 * Carry on if we have enough space (short-circuit) OR call
1470 * can_overcommit() to ensure we can overcommit to continue.
1471 */
1472 if (!pending_tickets &&
1473 ((used + orig_bytes <= space_info->total_bytes) ||
1474 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1475 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1476 orig_bytes);
1477 ret = 0;
1478 }
1479
1480 /*
1481 * If we couldn't make a reservation then setup our reservation ticket
1482 * and kick the async worker if it's not already running.
1483 *
1484 * If we are a priority flusher then we just need to add our ticket to
1485 * the list and we will do our own flushing further down.
1486 */
1487 if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
1488 ticket.bytes = orig_bytes;
1489 ticket.error = 0;
1490 space_info->reclaim_size += ticket.bytes;
1491 init_waitqueue_head(&ticket.wait);
1492 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1493 if (trace_btrfs_reserve_ticket_enabled())
1494 start_ns = ktime_get_ns();
1495
1496 if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1497 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1498 flush == BTRFS_RESERVE_FLUSH_DATA) {
1499 list_add_tail(&ticket.list, &space_info->tickets);
1500 if (!space_info->flush) {
1501 /*
1502 * We were forced to add a reserve ticket, so
1503 * our preemptive flushing is unable to keep
1504 * up. Clamp down on the threshold for the
1505 * preemptive flushing in order to keep up with
1506 * the workload.
1507 */
1508 maybe_clamp_preempt(fs_info, space_info);
1509
1510 space_info->flush = 1;
1511 trace_btrfs_trigger_flush(fs_info,
1512 space_info->flags,
1513 orig_bytes, flush,
1514 "enospc");
1515 queue_work(system_unbound_wq, async_work);
1516 }
1517 } else {
1518 list_add_tail(&ticket.list,
1519 &space_info->priority_tickets);
1520 }
1521 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1522 used += orig_bytes;
1523 /*
1524 * We will do the space reservation dance during log replay,
1525 * which means we won't have fs_info->fs_root set, so don't do
1526 * the async reclaim as we will panic.
1527 */
1528 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1529 !work_busy(&fs_info->preempt_reclaim_work) &&
1530 need_preemptive_reclaim(fs_info, space_info)) {
1531 trace_btrfs_trigger_flush(fs_info, space_info->flags,
1532 orig_bytes, flush, "preempt");
1533 queue_work(system_unbound_wq,
1534 &fs_info->preempt_reclaim_work);
1535 }
1536 }
1537 spin_unlock(&space_info->lock);
1538 if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
1539 return ret;
1540
1541 return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1542 orig_bytes, flush);
1543}
1544
1545/**
1546 * Trye to reserve metadata bytes from the block_rsv's space
1547 *
1548 * @root: the root we're allocating for
1549 * @block_rsv: block_rsv we're allocating for
1550 * @orig_bytes: number of bytes we want
1551 * @flush: whether or not we can flush to make our reservation
1552 *
1553 * This will reserve orig_bytes number of bytes from the space info associated
1554 * with the block_rsv. If there is not enough space it will make an attempt to
1555 * flush out space to make room. It will do this by flushing delalloc if
1556 * possible or committing the transaction. If flush is 0 then no attempts to
1557 * regain reservations will be made and this will fail if there is not enough
1558 * space already.
1559 */
1560int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
1561 struct btrfs_block_rsv *block_rsv,
1562 u64 orig_bytes,
1563 enum btrfs_reserve_flush_enum flush)
1564{
1565 struct btrfs_fs_info *fs_info = root->fs_info;
1566 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
1567 int ret;
1568
1569 ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush);
1570 if (ret == -ENOSPC &&
1571 unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
1572 if (block_rsv != global_rsv &&
1573 !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes))
1574 ret = 0;
1575 }
1576 if (ret == -ENOSPC) {
1577 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1578 block_rsv->space_info->flags,
1579 orig_bytes, 1);
1580
1581 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1582 btrfs_dump_space_info(fs_info, block_rsv->space_info,
1583 orig_bytes, 0);
1584 }
1585 return ret;
1586}
1587
1588/**
1589 * Try to reserve data bytes for an allocation
1590 *
1591 * @fs_info: the filesystem
1592 * @bytes: number of bytes we need
1593 * @flush: how we are allowed to flush
1594 *
1595 * This will reserve bytes from the data space info. If there is not enough
1596 * space then we will attempt to flush space as specified by flush.
1597 */
1598int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1599 enum btrfs_reserve_flush_enum flush)
1600{
1601 struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1602 int ret;
1603
1604 ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1605 flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE);
1606 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1607
1608 ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1609 if (ret == -ENOSPC) {
1610 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1611 data_sinfo->flags, bytes, 1);
1612 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1613 btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
1614 }
1615 return ret;
1616}