1 // SPDX-License-Identifier: GPL-2.0
5 #include "space-info.h"
8 #include "free-space-cache.h"
9 #include "ordered-data.h"
10 #include "transaction.h"
11 #include "block-group.h"
14 * HOW DOES SPACE RESERVATION WORK
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
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.
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.
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.
40 * MAKING RESERVATIONS, THE NORMAL CASE
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.
47 * space_info->bytes_may_reserve += num_bytes
50 * Call btrfs_add_reserved_bytes() which does
51 * space_info->bytes_may_reserve -= num_bytes
52 * space_info->bytes_reserved += extent_bytes
55 * Call btrfs_update_block_group() which does
56 * space_info->bytes_reserved -= extent_bytes
57 * space_info->bytes_used += extent_bytes
59 * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
61 * Assume we are unable to simply make the reservation because we do not have
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
68 * ->handle_reserve_ticket
69 * wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
72 * -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
73 * Flushes various things attempting to free up space.
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.
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
88 * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
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.
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.
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
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.
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.
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.
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.
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.
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
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.
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.
161 u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
162 bool may_use_included)
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);
172 * after adding space to the filesystem, we need to clear the full flags
173 * on all the space infos.
175 void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
177 struct list_head *head = &info->space_info;
178 struct btrfs_space_info *found;
180 list_for_each_entry(found, head, list)
184 static int create_space_info(struct btrfs_fs_info *info, u64 flags)
187 struct btrfs_space_info *space_info;
191 space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
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;
206 ret = btrfs_sysfs_add_space_info_type(info, space_info);
210 list_add(&space_info->list, &info->space_info);
211 if (flags & BTRFS_BLOCK_GROUP_DATA)
212 info->data_sinfo = space_info;
217 int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
219 struct btrfs_super_block *disk_super;
225 disk_super = fs_info->super_copy;
226 if (!btrfs_super_root(disk_super))
229 features = btrfs_super_incompat_flags(disk_super);
230 if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
233 flags = BTRFS_BLOCK_GROUP_SYSTEM;
234 ret = create_space_info(fs_info, flags);
239 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
240 ret = create_space_info(fs_info, flags);
242 flags = BTRFS_BLOCK_GROUP_METADATA;
243 ret = create_space_info(fs_info, flags);
247 flags = BTRFS_BLOCK_GROUP_DATA;
248 ret = create_space_info(fs_info, flags);
254 void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
255 u64 total_bytes, u64 bytes_used,
256 u64 bytes_readonly, u64 bytes_zone_unusable,
257 struct btrfs_space_info **space_info)
259 struct btrfs_space_info *found;
262 factor = btrfs_bg_type_to_factor(flags);
264 found = btrfs_find_space_info(info, flags);
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;
275 btrfs_try_granting_tickets(info, found);
276 spin_unlock(&found->lock);
280 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
283 struct list_head *head = &info->space_info;
284 struct btrfs_space_info *found;
286 flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
288 list_for_each_entry(found, head, list) {
289 if (found->flags & flags)
295 static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
296 struct btrfs_space_info *space_info,
297 enum btrfs_reserve_flush_enum flush)
303 if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
304 profile = btrfs_system_alloc_profile(fs_info);
306 profile = btrfs_metadata_alloc_profile(fs_info);
308 avail = atomic64_read(&fs_info->free_chunk_space);
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
316 factor = btrfs_bg_type_to_factor(profile);
317 avail = div_u64(avail, factor);
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.
324 if (flush == BTRFS_RESERVE_FLUSH_ALL)
331 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
332 struct btrfs_space_info *space_info, u64 bytes,
333 enum btrfs_reserve_flush_enum flush)
338 /* Don't overcommit when in mixed mode */
339 if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
342 used = btrfs_space_info_used(space_info, true);
343 avail = calc_available_free_space(fs_info, space_info, flush);
345 if (used + bytes < space_info->total_bytes + avail)
350 static void remove_ticket(struct btrfs_space_info *space_info,
351 struct reserve_ticket *ticket)
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;
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.
364 void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
365 struct btrfs_space_info *space_info)
367 struct list_head *head;
368 enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
370 lockdep_assert_held(&space_info->lock);
372 head = &space_info->priority_tickets;
374 while (!list_empty(head)) {
375 struct reserve_ticket *ticket;
376 u64 used = btrfs_space_info_used(space_info, true);
378 ticket = list_first_entry(head, struct reserve_ticket, list);
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,
384 btrfs_space_info_update_bytes_may_use(fs_info,
387 remove_ticket(space_info, ticket);
389 space_info->tickets_id++;
390 wake_up(&ticket->wait);
396 if (head == &space_info->priority_tickets) {
397 head = &space_info->tickets;
398 flush = BTRFS_RESERVE_FLUSH_ALL;
403 #define DUMP_BLOCK_RSV(fs_info, rsv_name) \
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); \
412 static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
413 struct btrfs_space_info *info)
415 lockdep_assert_held(&info->lock);
417 btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
419 info->total_bytes - btrfs_space_info_used(info, true),
420 info->full ? "" : "not ");
422 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
423 info->total_bytes, info->bytes_used, info->bytes_pinned,
424 info->bytes_reserved, info->bytes_may_use,
425 info->bytes_readonly, info->bytes_zone_unusable);
427 DUMP_BLOCK_RSV(fs_info, global_block_rsv);
428 DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
429 DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
430 DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
431 DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
435 void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
436 struct btrfs_space_info *info, u64 bytes,
437 int dump_block_groups)
439 struct btrfs_block_group *cache;
442 spin_lock(&info->lock);
443 __btrfs_dump_space_info(fs_info, info);
444 spin_unlock(&info->lock);
446 if (!dump_block_groups)
449 down_read(&info->groups_sem);
451 list_for_each_entry(cache, &info->block_groups[index], list) {
452 spin_lock(&cache->lock);
454 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu zone_unusable %s",
455 cache->start, cache->length, cache->used, cache->pinned,
456 cache->reserved, cache->zone_unusable,
457 cache->ro ? "[readonly]" : "");
458 spin_unlock(&cache->lock);
459 btrfs_dump_free_space(cache, bytes);
461 if (++index < BTRFS_NR_RAID_TYPES)
463 up_read(&info->groups_sem);
466 static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
472 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
473 nr = div64_u64(to_reclaim, bytes);
479 #define EXTENT_SIZE_PER_ITEM SZ_256K
482 * shrink metadata reservation for delalloc
484 static void shrink_delalloc(struct btrfs_fs_info *fs_info,
485 struct btrfs_space_info *space_info,
486 u64 to_reclaim, bool wait_ordered,
489 struct btrfs_trans_handle *trans;
496 /* Calc the number of the pages we need flush for space reservation */
497 if (to_reclaim == U64_MAX) {
501 * to_reclaim is set to however much metadata we need to
502 * reclaim, but reclaiming that much data doesn't really track
503 * exactly, so increase the amount to reclaim by 2x in order to
504 * make sure we're flushing enough delalloc to hopefully reclaim
505 * some metadata reservations.
507 items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
508 to_reclaim = items * EXTENT_SIZE_PER_ITEM;
511 trans = (struct btrfs_trans_handle *)current->journal_info;
513 delalloc_bytes = percpu_counter_sum_positive(
514 &fs_info->delalloc_bytes);
515 ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
516 if (delalloc_bytes == 0 && ordered_bytes == 0)
520 * If we are doing more ordered than delalloc we need to just wait on
521 * ordered extents, otherwise we'll waste time trying to flush delalloc
522 * that likely won't give us the space back we need.
524 if (ordered_bytes > delalloc_bytes && !for_preempt)
528 while ((delalloc_bytes || ordered_bytes) && loops < 3) {
529 u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
530 long nr_pages = min_t(u64, temp, LONG_MAX);
532 btrfs_start_delalloc_roots(fs_info, nr_pages, true);
535 if (wait_ordered && !trans) {
536 btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
538 time_left = schedule_timeout_killable(1);
544 * If we are for preemption we just want a one-shot of delalloc
545 * flushing so we can stop flushing if we decide we don't need
551 spin_lock(&space_info->lock);
552 if (list_empty(&space_info->tickets) &&
553 list_empty(&space_info->priority_tickets)) {
554 spin_unlock(&space_info->lock);
557 spin_unlock(&space_info->lock);
559 delalloc_bytes = percpu_counter_sum_positive(
560 &fs_info->delalloc_bytes);
561 ordered_bytes = percpu_counter_sum_positive(
562 &fs_info->ordered_bytes);
567 * Try to flush some data based on policy set by @state. This is only advisory
568 * and may fail for various reasons. The caller is supposed to examine the
569 * state of @space_info to detect the outcome.
571 static void flush_space(struct btrfs_fs_info *fs_info,
572 struct btrfs_space_info *space_info, u64 num_bytes,
573 enum btrfs_flush_state state, bool for_preempt)
575 struct btrfs_root *root = fs_info->extent_root;
576 struct btrfs_trans_handle *trans;
581 case FLUSH_DELAYED_ITEMS_NR:
582 case FLUSH_DELAYED_ITEMS:
583 if (state == FLUSH_DELAYED_ITEMS_NR)
584 nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
588 trans = btrfs_join_transaction(root);
590 ret = PTR_ERR(trans);
593 ret = btrfs_run_delayed_items_nr(trans, nr);
594 btrfs_end_transaction(trans);
597 case FLUSH_DELALLOC_WAIT:
598 shrink_delalloc(fs_info, space_info, num_bytes,
599 state == FLUSH_DELALLOC_WAIT, for_preempt);
601 case FLUSH_DELAYED_REFS_NR:
602 case FLUSH_DELAYED_REFS:
603 trans = btrfs_join_transaction(root);
605 ret = PTR_ERR(trans);
608 if (state == FLUSH_DELAYED_REFS_NR)
609 nr = calc_reclaim_items_nr(fs_info, num_bytes);
612 btrfs_run_delayed_refs(trans, nr);
613 btrfs_end_transaction(trans);
616 case ALLOC_CHUNK_FORCE:
617 trans = btrfs_join_transaction(root);
619 ret = PTR_ERR(trans);
622 ret = btrfs_chunk_alloc(trans,
623 btrfs_get_alloc_profile(fs_info, space_info->flags),
624 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
626 btrfs_end_transaction(trans);
627 if (ret > 0 || ret == -ENOSPC)
630 case RUN_DELAYED_IPUTS:
632 * If we have pending delayed iputs then we could free up a
633 * bunch of pinned space, so make sure we run the iputs before
634 * we do our pinned bytes check below.
636 btrfs_run_delayed_iputs(fs_info);
637 btrfs_wait_on_delayed_iputs(fs_info);
640 ASSERT(current->journal_info == NULL);
641 trans = btrfs_join_transaction(root);
643 ret = PTR_ERR(trans);
646 ret = btrfs_commit_transaction(trans);
653 trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
659 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
660 struct btrfs_space_info *space_info)
664 u64 to_reclaim = space_info->reclaim_size;
666 lockdep_assert_held(&space_info->lock);
668 avail = calc_available_free_space(fs_info, space_info,
669 BTRFS_RESERVE_FLUSH_ALL);
670 used = btrfs_space_info_used(space_info, true);
673 * We may be flushing because suddenly we have less space than we had
674 * before, and now we're well over-committed based on our current free
675 * space. If that's the case add in our overage so we make sure to put
676 * appropriate pressure on the flushing state machine.
678 if (space_info->total_bytes + avail < used)
679 to_reclaim += used - (space_info->total_bytes + avail);
684 static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
685 struct btrfs_space_info *space_info)
687 u64 global_rsv_size = fs_info->global_block_rsv.reserved;
688 u64 ordered, delalloc;
689 u64 thresh = div_factor_fine(space_info->total_bytes, 98);
692 /* If we're just plain full then async reclaim just slows us down. */
693 if ((space_info->bytes_used + space_info->bytes_reserved +
694 global_rsv_size) >= thresh)
698 * We have tickets queued, bail so we don't compete with the async
701 if (space_info->reclaim_size)
705 * If we have over half of the free space occupied by reservations or
706 * pinned then we want to start flushing.
708 * We do not do the traditional thing here, which is to say
710 * if (used >= ((total_bytes + avail) / 2))
713 * because this doesn't quite work how we want. If we had more than 50%
714 * of the space_info used by bytes_used and we had 0 available we'd just
715 * constantly run the background flusher. Instead we want it to kick in
716 * if our reclaimable space exceeds our clamped free space.
718 * Our clamping range is 2^1 -> 2^8. Practically speaking that means
721 * Amount of RAM Minimum threshold Maximum threshold
724 * 128GiB 512MiB 64GiB
729 * These are the range our thresholds will fall in, corresponding to how
730 * much delalloc we need for the background flusher to kick in.
733 thresh = calc_available_free_space(fs_info, space_info,
734 BTRFS_RESERVE_FLUSH_ALL);
735 used = space_info->bytes_used + space_info->bytes_reserved +
736 space_info->bytes_readonly + global_rsv_size;
737 if (used < space_info->total_bytes)
738 thresh += space_info->total_bytes - used;
739 thresh >>= space_info->clamp;
741 used = space_info->bytes_pinned;
744 * If we have more ordered bytes than delalloc bytes then we're either
745 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
746 * around. Preemptive flushing is only useful in that it can free up
747 * space before tickets need to wait for things to finish. In the case
748 * of ordered extents, preemptively waiting on ordered extents gets us
749 * nothing, if our reservations are tied up in ordered extents we'll
750 * simply have to slow down writers by forcing them to wait on ordered
753 * In the case that ordered is larger than delalloc, only include the
754 * block reserves that we would actually be able to directly reclaim
755 * from. In this case if we're heavy on metadata operations this will
756 * clearly be heavy enough to warrant preemptive flushing. In the case
757 * of heavy DIO or ordered reservations, preemptive flushing will just
758 * waste time and cause us to slow down.
760 * We want to make sure we truly are maxed out on ordered however, so
761 * cut ordered in half, and if it's still higher than delalloc then we
762 * can keep flushing. This is to avoid the case where we start
763 * flushing, and now delalloc == ordered and we stop preemptively
764 * flushing when we could still have several gigs of delalloc to flush.
766 ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
767 delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
768 if (ordered >= delalloc)
769 used += fs_info->delayed_refs_rsv.reserved +
770 fs_info->delayed_block_rsv.reserved;
772 used += space_info->bytes_may_use - global_rsv_size;
774 return (used >= thresh && !btrfs_fs_closing(fs_info) &&
775 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
778 static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
779 struct btrfs_space_info *space_info,
780 struct reserve_ticket *ticket)
782 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
785 if (global_rsv->space_info != space_info)
788 spin_lock(&global_rsv->lock);
789 min_bytes = div_factor(global_rsv->size, 1);
790 if (global_rsv->reserved < min_bytes + ticket->bytes) {
791 spin_unlock(&global_rsv->lock);
794 global_rsv->reserved -= ticket->bytes;
795 remove_ticket(space_info, ticket);
797 wake_up(&ticket->wait);
798 space_info->tickets_id++;
799 if (global_rsv->reserved < global_rsv->size)
800 global_rsv->full = 0;
801 spin_unlock(&global_rsv->lock);
807 * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets
808 * @fs_info - fs_info for this fs
809 * @space_info - the space info we were flushing
811 * We call this when we've exhausted our flushing ability and haven't made
812 * progress in satisfying tickets. The reservation code handles tickets in
813 * order, so if there is a large ticket first and then smaller ones we could
814 * very well satisfy the smaller tickets. This will attempt to wake up any
815 * tickets in the list to catch this case.
817 * This function returns true if it was able to make progress by clearing out
818 * other tickets, or if it stumbles across a ticket that was smaller than the
821 static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
822 struct btrfs_space_info *space_info)
824 struct reserve_ticket *ticket;
825 u64 tickets_id = space_info->tickets_id;
827 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
828 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
829 __btrfs_dump_space_info(fs_info, space_info);
832 while (!list_empty(&space_info->tickets) &&
833 tickets_id == space_info->tickets_id) {
834 ticket = list_first_entry(&space_info->tickets,
835 struct reserve_ticket, list);
838 steal_from_global_rsv(fs_info, space_info, ticket))
841 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
842 btrfs_info(fs_info, "failing ticket with %llu bytes",
845 remove_ticket(space_info, ticket);
846 ticket->error = -ENOSPC;
847 wake_up(&ticket->wait);
850 * We're just throwing tickets away, so more flushing may not
851 * trip over btrfs_try_granting_tickets, so we need to call it
852 * here to see if we can make progress with the next ticket in
855 btrfs_try_granting_tickets(fs_info, space_info);
857 return (tickets_id != space_info->tickets_id);
861 * This is for normal flushers, we can wait all goddamned day if we want to. We
862 * will loop and continuously try to flush as long as we are making progress.
863 * We count progress as clearing off tickets each time we have to loop.
865 static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
867 struct btrfs_fs_info *fs_info;
868 struct btrfs_space_info *space_info;
870 enum btrfs_flush_state flush_state;
871 int commit_cycles = 0;
874 fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
875 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
877 spin_lock(&space_info->lock);
878 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
880 space_info->flush = 0;
881 spin_unlock(&space_info->lock);
884 last_tickets_id = space_info->tickets_id;
885 spin_unlock(&space_info->lock);
887 flush_state = FLUSH_DELAYED_ITEMS_NR;
889 flush_space(fs_info, space_info, to_reclaim, flush_state, false);
890 spin_lock(&space_info->lock);
891 if (list_empty(&space_info->tickets)) {
892 space_info->flush = 0;
893 spin_unlock(&space_info->lock);
896 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
898 if (last_tickets_id == space_info->tickets_id) {
901 last_tickets_id = space_info->tickets_id;
902 flush_state = FLUSH_DELAYED_ITEMS_NR;
908 * We don't want to force a chunk allocation until we've tried
909 * pretty hard to reclaim space. Think of the case where we
910 * freed up a bunch of space and so have a lot of pinned space
911 * to reclaim. We would rather use that than possibly create a
912 * underutilized metadata chunk. So if this is our first run
913 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
914 * commit the transaction. If nothing has changed the next go
915 * around then we can force a chunk allocation.
917 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
920 if (flush_state > COMMIT_TRANS) {
922 if (commit_cycles > 2) {
923 if (maybe_fail_all_tickets(fs_info, space_info)) {
924 flush_state = FLUSH_DELAYED_ITEMS_NR;
927 space_info->flush = 0;
930 flush_state = FLUSH_DELAYED_ITEMS_NR;
933 spin_unlock(&space_info->lock);
934 } while (flush_state <= COMMIT_TRANS);
938 * This handles pre-flushing of metadata space before we get to the point that
939 * we need to start blocking threads on tickets. The logic here is different
940 * from the other flush paths because it doesn't rely on tickets to tell us how
941 * much we need to flush, instead it attempts to keep us below the 80% full
942 * watermark of space by flushing whichever reservation pool is currently the
945 static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
947 struct btrfs_fs_info *fs_info;
948 struct btrfs_space_info *space_info;
949 struct btrfs_block_rsv *delayed_block_rsv;
950 struct btrfs_block_rsv *delayed_refs_rsv;
951 struct btrfs_block_rsv *global_rsv;
952 struct btrfs_block_rsv *trans_rsv;
955 fs_info = container_of(work, struct btrfs_fs_info,
956 preempt_reclaim_work);
957 space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
958 delayed_block_rsv = &fs_info->delayed_block_rsv;
959 delayed_refs_rsv = &fs_info->delayed_refs_rsv;
960 global_rsv = &fs_info->global_block_rsv;
961 trans_rsv = &fs_info->trans_block_rsv;
963 spin_lock(&space_info->lock);
964 while (need_preemptive_reclaim(fs_info, space_info)) {
965 enum btrfs_flush_state flush;
966 u64 delalloc_size = 0;
967 u64 to_reclaim, block_rsv_size;
968 u64 global_rsv_size = global_rsv->reserved;
973 * We don't have a precise counter for the metadata being
974 * reserved for delalloc, so we'll approximate it by subtracting
975 * out the block rsv's space from the bytes_may_use. If that
976 * amount is higher than the individual reserves, then we can
977 * assume it's tied up in delalloc reservations.
979 block_rsv_size = global_rsv_size +
980 delayed_block_rsv->reserved +
981 delayed_refs_rsv->reserved +
983 if (block_rsv_size < space_info->bytes_may_use)
984 delalloc_size = space_info->bytes_may_use - block_rsv_size;
985 spin_unlock(&space_info->lock);
988 * We don't want to include the global_rsv in our calculation,
989 * because that's space we can't touch. Subtract it from the
990 * block_rsv_size for the next checks.
992 block_rsv_size -= global_rsv_size;
995 * We really want to avoid flushing delalloc too much, as it
996 * could result in poor allocation patterns, so only flush it if
997 * it's larger than the rest of the pools combined.
999 if (delalloc_size > block_rsv_size) {
1000 to_reclaim = delalloc_size;
1001 flush = FLUSH_DELALLOC;
1002 } else if (space_info->bytes_pinned >
1003 (delayed_block_rsv->reserved +
1004 delayed_refs_rsv->reserved)) {
1005 to_reclaim = space_info->bytes_pinned;
1006 flush = COMMIT_TRANS;
1007 } else if (delayed_block_rsv->reserved >
1008 delayed_refs_rsv->reserved) {
1009 to_reclaim = delayed_block_rsv->reserved;
1010 flush = FLUSH_DELAYED_ITEMS_NR;
1012 to_reclaim = delayed_refs_rsv->reserved;
1013 flush = FLUSH_DELAYED_REFS_NR;
1017 * We don't want to reclaim everything, just a portion, so scale
1018 * down the to_reclaim by 1/4. If it takes us down to 0,
1019 * reclaim 1 items worth.
1023 to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1024 flush_space(fs_info, space_info, to_reclaim, flush, true);
1026 spin_lock(&space_info->lock);
1029 /* We only went through once, back off our clamping. */
1030 if (loops == 1 && !space_info->reclaim_size)
1031 space_info->clamp = max(1, space_info->clamp - 1);
1032 trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1033 spin_unlock(&space_info->lock);
1037 * FLUSH_DELALLOC_WAIT:
1038 * Space is freed from flushing delalloc in one of two ways.
1040 * 1) compression is on and we allocate less space than we reserved
1041 * 2) we are overwriting existing space
1043 * For #1 that extra space is reclaimed as soon as the delalloc pages are
1044 * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1045 * length to ->bytes_reserved, and subtracts the reserved space from
1048 * For #2 this is trickier. Once the ordered extent runs we will drop the
1049 * extent in the range we are overwriting, which creates a delayed ref for
1050 * that freed extent. This however is not reclaimed until the transaction
1051 * commits, thus the next stages.
1054 * If we are freeing inodes, we want to make sure all delayed iputs have
1055 * completed, because they could have been on an inode with i_nlink == 0, and
1056 * thus have been truncated and freed up space. But again this space is not
1057 * immediately re-usable, it comes in the form of a delayed ref, which must be
1058 * run and then the transaction must be committed.
1061 * This is where we reclaim all of the pinned space generated by running the
1065 * For data we start with alloc chunk force, however we could have been full
1066 * before, and then the transaction commit could have freed new block groups,
1067 * so if we now have space to allocate do the force chunk allocation.
1069 static const enum btrfs_flush_state data_flush_states[] = {
1070 FLUSH_DELALLOC_WAIT,
1076 static void btrfs_async_reclaim_data_space(struct work_struct *work)
1078 struct btrfs_fs_info *fs_info;
1079 struct btrfs_space_info *space_info;
1080 u64 last_tickets_id;
1081 enum btrfs_flush_state flush_state = 0;
1083 fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1084 space_info = fs_info->data_sinfo;
1086 spin_lock(&space_info->lock);
1087 if (list_empty(&space_info->tickets)) {
1088 space_info->flush = 0;
1089 spin_unlock(&space_info->lock);
1092 last_tickets_id = space_info->tickets_id;
1093 spin_unlock(&space_info->lock);
1095 while (!space_info->full) {
1096 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1097 spin_lock(&space_info->lock);
1098 if (list_empty(&space_info->tickets)) {
1099 space_info->flush = 0;
1100 spin_unlock(&space_info->lock);
1103 last_tickets_id = space_info->tickets_id;
1104 spin_unlock(&space_info->lock);
1107 while (flush_state < ARRAY_SIZE(data_flush_states)) {
1108 flush_space(fs_info, space_info, U64_MAX,
1109 data_flush_states[flush_state], false);
1110 spin_lock(&space_info->lock);
1111 if (list_empty(&space_info->tickets)) {
1112 space_info->flush = 0;
1113 spin_unlock(&space_info->lock);
1117 if (last_tickets_id == space_info->tickets_id) {
1120 last_tickets_id = space_info->tickets_id;
1124 if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1125 if (space_info->full) {
1126 if (maybe_fail_all_tickets(fs_info, space_info))
1129 space_info->flush = 0;
1134 spin_unlock(&space_info->lock);
1138 void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1140 INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1141 INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1142 INIT_WORK(&fs_info->preempt_reclaim_work,
1143 btrfs_preempt_reclaim_metadata_space);
1146 static const enum btrfs_flush_state priority_flush_states[] = {
1147 FLUSH_DELAYED_ITEMS_NR,
1148 FLUSH_DELAYED_ITEMS,
1152 static const enum btrfs_flush_state evict_flush_states[] = {
1153 FLUSH_DELAYED_ITEMS_NR,
1154 FLUSH_DELAYED_ITEMS,
1155 FLUSH_DELAYED_REFS_NR,
1158 FLUSH_DELALLOC_WAIT,
1163 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1164 struct btrfs_space_info *space_info,
1165 struct reserve_ticket *ticket,
1166 const enum btrfs_flush_state *states,
1172 spin_lock(&space_info->lock);
1173 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1175 spin_unlock(&space_info->lock);
1178 spin_unlock(&space_info->lock);
1182 flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1185 spin_lock(&space_info->lock);
1186 if (ticket->bytes == 0) {
1187 spin_unlock(&space_info->lock);
1190 spin_unlock(&space_info->lock);
1191 } while (flush_state < states_nr);
1194 static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1195 struct btrfs_space_info *space_info,
1196 struct reserve_ticket *ticket)
1198 while (!space_info->full) {
1199 flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1200 spin_lock(&space_info->lock);
1201 if (ticket->bytes == 0) {
1202 spin_unlock(&space_info->lock);
1205 spin_unlock(&space_info->lock);
1209 static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1210 struct btrfs_space_info *space_info,
1211 struct reserve_ticket *ticket)
1217 spin_lock(&space_info->lock);
1218 while (ticket->bytes > 0 && ticket->error == 0) {
1219 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1222 * Delete us from the list. After we unlock the space
1223 * info, we don't want the async reclaim job to reserve
1224 * space for this ticket. If that would happen, then the
1225 * ticket's task would not known that space was reserved
1226 * despite getting an error, resulting in a space leak
1227 * (bytes_may_use counter of our space_info).
1229 remove_ticket(space_info, ticket);
1230 ticket->error = -EINTR;
1233 spin_unlock(&space_info->lock);
1237 finish_wait(&ticket->wait, &wait);
1238 spin_lock(&space_info->lock);
1240 spin_unlock(&space_info->lock);
1244 * Do the appropriate flushing and waiting for a ticket
1246 * @fs_info: the filesystem
1247 * @space_info: space info for the reservation
1248 * @ticket: ticket for the reservation
1249 * @start_ns: timestamp when the reservation started
1250 * @orig_bytes: amount of bytes originally reserved
1251 * @flush: how much we can flush
1253 * This does the work of figuring out how to flush for the ticket, waiting for
1254 * the reservation, and returning the appropriate error if there is one.
1256 static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1257 struct btrfs_space_info *space_info,
1258 struct reserve_ticket *ticket,
1259 u64 start_ns, u64 orig_bytes,
1260 enum btrfs_reserve_flush_enum flush)
1265 case BTRFS_RESERVE_FLUSH_DATA:
1266 case BTRFS_RESERVE_FLUSH_ALL:
1267 case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1268 wait_reserve_ticket(fs_info, space_info, ticket);
1270 case BTRFS_RESERVE_FLUSH_LIMIT:
1271 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1272 priority_flush_states,
1273 ARRAY_SIZE(priority_flush_states));
1275 case BTRFS_RESERVE_FLUSH_EVICT:
1276 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1278 ARRAY_SIZE(evict_flush_states));
1280 case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1281 priority_reclaim_data_space(fs_info, space_info, ticket);
1288 spin_lock(&space_info->lock);
1289 ret = ticket->error;
1290 if (ticket->bytes || ticket->error) {
1292 * We were a priority ticket, so we need to delete ourselves
1293 * from the list. Because we could have other priority tickets
1294 * behind us that require less space, run
1295 * btrfs_try_granting_tickets() to see if their reservations can
1298 if (!list_empty(&ticket->list)) {
1299 remove_ticket(space_info, ticket);
1300 btrfs_try_granting_tickets(fs_info, space_info);
1306 spin_unlock(&space_info->lock);
1307 ASSERT(list_empty(&ticket->list));
1309 * Check that we can't have an error set if the reservation succeeded,
1310 * as that would confuse tasks and lead them to error out without
1311 * releasing reserved space (if an error happens the expectation is that
1312 * space wasn't reserved at all).
1314 ASSERT(!(ticket->bytes == 0 && ticket->error));
1315 trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1316 start_ns, flush, ticket->error);
1321 * This returns true if this flush state will go through the ordinary flushing
1324 static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1326 return (flush == BTRFS_RESERVE_FLUSH_ALL) ||
1327 (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1330 static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1331 struct btrfs_space_info *space_info)
1333 u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1334 u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1337 * If we're heavy on ordered operations then clamping won't help us. We
1338 * need to clamp specifically to keep up with dirty'ing buffered
1339 * writers, because there's not a 1:1 correlation of writing delalloc
1340 * and freeing space, like there is with flushing delayed refs or
1341 * delayed nodes. If we're already more ordered than delalloc then
1342 * we're keeping up, otherwise we aren't and should probably clamp.
1344 if (ordered < delalloc)
1345 space_info->clamp = min(space_info->clamp + 1, 8);
1349 * Try to reserve bytes from the block_rsv's space
1351 * @fs_info: the filesystem
1352 * @space_info: space info we want to allocate from
1353 * @orig_bytes: number of bytes we want
1354 * @flush: whether or not we can flush to make our reservation
1356 * This will reserve orig_bytes number of bytes from the space info associated
1357 * with the block_rsv. If there is not enough space it will make an attempt to
1358 * flush out space to make room. It will do this by flushing delalloc if
1359 * possible or committing the transaction. If flush is 0 then no attempts to
1360 * regain reservations will be made and this will fail if there is not enough
1363 static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1364 struct btrfs_space_info *space_info, u64 orig_bytes,
1365 enum btrfs_reserve_flush_enum flush)
1367 struct work_struct *async_work;
1368 struct reserve_ticket ticket;
1372 bool pending_tickets;
1375 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
1377 if (flush == BTRFS_RESERVE_FLUSH_DATA)
1378 async_work = &fs_info->async_data_reclaim_work;
1380 async_work = &fs_info->async_reclaim_work;
1382 spin_lock(&space_info->lock);
1384 used = btrfs_space_info_used(space_info, true);
1387 * We don't want NO_FLUSH allocations to jump everybody, they can
1388 * generally handle ENOSPC in a different way, so treat them the same as
1389 * normal flushers when it comes to skipping pending tickets.
1391 if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1392 pending_tickets = !list_empty(&space_info->tickets) ||
1393 !list_empty(&space_info->priority_tickets);
1395 pending_tickets = !list_empty(&space_info->priority_tickets);
1398 * Carry on if we have enough space (short-circuit) OR call
1399 * can_overcommit() to ensure we can overcommit to continue.
1401 if (!pending_tickets &&
1402 ((used + orig_bytes <= space_info->total_bytes) ||
1403 btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1404 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1410 * If we couldn't make a reservation then setup our reservation ticket
1411 * and kick the async worker if it's not already running.
1413 * If we are a priority flusher then we just need to add our ticket to
1414 * the list and we will do our own flushing further down.
1416 if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
1417 ticket.bytes = orig_bytes;
1419 space_info->reclaim_size += ticket.bytes;
1420 init_waitqueue_head(&ticket.wait);
1421 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1422 if (trace_btrfs_reserve_ticket_enabled())
1423 start_ns = ktime_get_ns();
1425 if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1426 flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1427 flush == BTRFS_RESERVE_FLUSH_DATA) {
1428 list_add_tail(&ticket.list, &space_info->tickets);
1429 if (!space_info->flush) {
1431 * We were forced to add a reserve ticket, so
1432 * our preemptive flushing is unable to keep
1433 * up. Clamp down on the threshold for the
1434 * preemptive flushing in order to keep up with
1437 maybe_clamp_preempt(fs_info, space_info);
1439 space_info->flush = 1;
1440 trace_btrfs_trigger_flush(fs_info,
1444 queue_work(system_unbound_wq, async_work);
1447 list_add_tail(&ticket.list,
1448 &space_info->priority_tickets);
1450 } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1453 * We will do the space reservation dance during log replay,
1454 * which means we won't have fs_info->fs_root set, so don't do
1455 * the async reclaim as we will panic.
1457 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1458 !work_busy(&fs_info->preempt_reclaim_work) &&
1459 need_preemptive_reclaim(fs_info, space_info)) {
1460 trace_btrfs_trigger_flush(fs_info, space_info->flags,
1461 orig_bytes, flush, "preempt");
1462 queue_work(system_unbound_wq,
1463 &fs_info->preempt_reclaim_work);
1466 spin_unlock(&space_info->lock);
1467 if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
1470 return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1475 * Trye to reserve metadata bytes from the block_rsv's space
1477 * @root: the root we're allocating for
1478 * @block_rsv: block_rsv we're allocating for
1479 * @orig_bytes: number of bytes we want
1480 * @flush: whether or not we can flush to make our reservation
1482 * This will reserve orig_bytes number of bytes from the space info associated
1483 * with the block_rsv. If there is not enough space it will make an attempt to
1484 * flush out space to make room. It will do this by flushing delalloc if
1485 * possible or committing the transaction. If flush is 0 then no attempts to
1486 * regain reservations will be made and this will fail if there is not enough
1489 int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
1490 struct btrfs_block_rsv *block_rsv,
1492 enum btrfs_reserve_flush_enum flush)
1494 struct btrfs_fs_info *fs_info = root->fs_info;
1495 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
1498 ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush);
1499 if (ret == -ENOSPC &&
1500 unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
1501 if (block_rsv != global_rsv &&
1502 !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes))
1505 if (ret == -ENOSPC) {
1506 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1507 block_rsv->space_info->flags,
1510 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1511 btrfs_dump_space_info(fs_info, block_rsv->space_info,
1518 * Try to reserve data bytes for an allocation
1520 * @fs_info: the filesystem
1521 * @bytes: number of bytes we need
1522 * @flush: how we are allowed to flush
1524 * This will reserve bytes from the data space info. If there is not enough
1525 * space then we will attempt to flush space as specified by flush.
1527 int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1528 enum btrfs_reserve_flush_enum flush)
1530 struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1533 ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1534 flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE);
1535 ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1537 ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1538 if (ret == -ENOSPC) {
1539 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1540 data_sinfo->flags, bytes, 1);
1541 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1542 btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);