1 // SPDX-License-Identifier: GPL-2.0
6 #include "space-info.h"
7 #include "transaction.h"
8 #include "block-group.h"
12 * HOW DO BLOCK RESERVES WORK
14 * Think of block_rsv's as buckets for logically grouped metadata
15 * reservations. Each block_rsv has a ->size and a ->reserved. ->size is
16 * how large we want our block rsv to be, ->reserved is how much space is
17 * currently reserved for this block reserve.
19 * ->failfast exists for the truncate case, and is described below.
24 * Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
26 * We call into btrfs_reserve_metadata_bytes() with our bytes, which is
27 * accounted for in space_info->bytes_may_use, and then add the bytes to
28 * ->reserved, and ->size in the case of btrfs_block_rsv_add.
30 * ->size is an over-estimation of how much we may use for a particular
34 * Entrance: btrfs_use_block_rsv
36 * When we do a btrfs_alloc_tree_block() we call into btrfs_use_block_rsv()
37 * to determine the appropriate block_rsv to use, and then verify that
38 * ->reserved has enough space for our tree block allocation. Once
39 * successful we subtract fs_info->nodesize from ->reserved.
42 * Entrance: btrfs_block_rsv_release
44 * We are finished with our operation, subtract our individual reservation
45 * from ->size, and then subtract ->size from ->reserved and free up the
46 * excess if there is any.
48 * There is some logic here to refill the delayed refs rsv or the global rsv
49 * as needed, otherwise the excess is subtracted from
50 * space_info->bytes_may_use.
52 * TYPES OF BLOCK RESERVES
54 * BLOCK_RSV_TRANS, BLOCK_RSV_DELOPS, BLOCK_RSV_CHUNK
55 * These behave normally, as described above, just within the confines of the
56 * lifetime of their particular operation (transaction for the whole trans
57 * handle lifetime, for example).
60 * It is impossible to properly account for all the space that may be required
61 * to make our extent tree updates. This block reserve acts as an overflow
62 * buffer in case our delayed refs reserve does not reserve enough space to
63 * update the extent tree.
65 * We can steal from this in some cases as well, notably on evict() or
66 * truncate() in order to help users recover from ENOSPC conditions.
69 * The individual item sizes are determined by the per-inode size
70 * calculations, which are described with the delalloc code. This is pretty
71 * straightforward, it's just the calculation of ->size encodes a lot of
72 * different items, and thus it gets used when updating inodes, inserting file
73 * extents, and inserting checksums.
76 * We keep a running tally of how many delayed refs we have on the system.
77 * We assume each one of these delayed refs are going to use a full
78 * reservation. We use the transaction items and pre-reserve space for every
79 * operation, and use this reservation to refill any gap between ->size and
80 * ->reserved that may exist.
82 * From there it's straightforward, removing a delayed ref means we remove its
83 * count from ->size and free up reservations as necessary. Since this is
84 * the most dynamic block reserve in the system, we will try to refill this
85 * block reserve first with any excess returned by any other block reserve.
88 * This is the fallback block reserve to make us try to reserve space if we
89 * don't have a specific bucket for this allocation. It is mostly used for
90 * updating the device tree and such, since that is a separate pool we're
91 * content to just reserve space from the space_info on demand.
94 * This is used by things like truncate and iput. We will temporarily
95 * allocate a block reserve, set it to some size, and then truncate bytes
96 * until we have no space left. With ->failfast set we'll simply return
97 * ENOSPC from btrfs_use_block_rsv() to signal that we need to unwind and try
98 * to make a new reservation. This is because these operations are
99 * unbounded, so we want to do as much work as we can, and then back off and
103 static u64
block_rsv_release_bytes(struct btrfs_fs_info
*fs_info
,
104 struct btrfs_block_rsv
*block_rsv
,
105 struct btrfs_block_rsv
*dest
, u64 num_bytes
,
106 u64
*qgroup_to_release_ret
)
108 struct btrfs_space_info
*space_info
= block_rsv
->space_info
;
109 u64 qgroup_to_release
= 0;
112 spin_lock(&block_rsv
->lock
);
113 if (num_bytes
== (u64
)-1) {
114 num_bytes
= block_rsv
->size
;
115 qgroup_to_release
= block_rsv
->qgroup_rsv_size
;
117 block_rsv
->size
-= num_bytes
;
118 if (block_rsv
->reserved
>= block_rsv
->size
) {
119 num_bytes
= block_rsv
->reserved
- block_rsv
->size
;
120 block_rsv
->reserved
= block_rsv
->size
;
125 if (block_rsv
->qgroup_rsv_reserved
>= block_rsv
->qgroup_rsv_size
) {
126 qgroup_to_release
= block_rsv
->qgroup_rsv_reserved
-
127 block_rsv
->qgroup_rsv_size
;
128 block_rsv
->qgroup_rsv_reserved
= block_rsv
->qgroup_rsv_size
;
130 qgroup_to_release
= 0;
132 spin_unlock(&block_rsv
->lock
);
137 spin_lock(&dest
->lock
);
141 bytes_to_add
= dest
->size
- dest
->reserved
;
142 bytes_to_add
= min(num_bytes
, bytes_to_add
);
143 dest
->reserved
+= bytes_to_add
;
144 if (dest
->reserved
>= dest
->size
)
146 num_bytes
-= bytes_to_add
;
148 spin_unlock(&dest
->lock
);
151 btrfs_space_info_free_bytes_may_use(fs_info
,
155 if (qgroup_to_release_ret
)
156 *qgroup_to_release_ret
= qgroup_to_release
;
160 int btrfs_block_rsv_migrate(struct btrfs_block_rsv
*src
,
161 struct btrfs_block_rsv
*dst
, u64 num_bytes
,
166 ret
= btrfs_block_rsv_use_bytes(src
, num_bytes
);
170 btrfs_block_rsv_add_bytes(dst
, num_bytes
, update_size
);
174 void btrfs_init_block_rsv(struct btrfs_block_rsv
*rsv
, unsigned short type
)
176 memset(rsv
, 0, sizeof(*rsv
));
177 spin_lock_init(&rsv
->lock
);
181 void btrfs_init_metadata_block_rsv(struct btrfs_fs_info
*fs_info
,
182 struct btrfs_block_rsv
*rsv
,
185 btrfs_init_block_rsv(rsv
, type
);
186 rsv
->space_info
= btrfs_find_space_info(fs_info
,
187 BTRFS_BLOCK_GROUP_METADATA
);
190 struct btrfs_block_rsv
*btrfs_alloc_block_rsv(struct btrfs_fs_info
*fs_info
,
193 struct btrfs_block_rsv
*block_rsv
;
195 block_rsv
= kmalloc(sizeof(*block_rsv
), GFP_NOFS
);
199 btrfs_init_metadata_block_rsv(fs_info
, block_rsv
, type
);
203 void btrfs_free_block_rsv(struct btrfs_fs_info
*fs_info
,
204 struct btrfs_block_rsv
*rsv
)
208 btrfs_block_rsv_release(fs_info
, rsv
, (u64
)-1, NULL
);
212 int btrfs_block_rsv_add(struct btrfs_fs_info
*fs_info
,
213 struct btrfs_block_rsv
*block_rsv
, u64 num_bytes
,
214 enum btrfs_reserve_flush_enum flush
)
221 ret
= btrfs_reserve_metadata_bytes(fs_info
, block_rsv
, num_bytes
, flush
);
223 btrfs_block_rsv_add_bytes(block_rsv
, num_bytes
, true);
228 int btrfs_block_rsv_check(struct btrfs_block_rsv
*block_rsv
, int min_factor
)
236 spin_lock(&block_rsv
->lock
);
237 num_bytes
= div_factor(block_rsv
->size
, min_factor
);
238 if (block_rsv
->reserved
>= num_bytes
)
240 spin_unlock(&block_rsv
->lock
);
245 int btrfs_block_rsv_refill(struct btrfs_fs_info
*fs_info
,
246 struct btrfs_block_rsv
*block_rsv
, u64 min_reserved
,
247 enum btrfs_reserve_flush_enum flush
)
255 spin_lock(&block_rsv
->lock
);
256 num_bytes
= min_reserved
;
257 if (block_rsv
->reserved
>= num_bytes
)
260 num_bytes
-= block_rsv
->reserved
;
261 spin_unlock(&block_rsv
->lock
);
266 ret
= btrfs_reserve_metadata_bytes(fs_info
, block_rsv
, num_bytes
, flush
);
268 btrfs_block_rsv_add_bytes(block_rsv
, num_bytes
, false);
275 u64
btrfs_block_rsv_release(struct btrfs_fs_info
*fs_info
,
276 struct btrfs_block_rsv
*block_rsv
, u64 num_bytes
,
277 u64
*qgroup_to_release
)
279 struct btrfs_block_rsv
*global_rsv
= &fs_info
->global_block_rsv
;
280 struct btrfs_block_rsv
*delayed_rsv
= &fs_info
->delayed_refs_rsv
;
281 struct btrfs_block_rsv
*target
= NULL
;
284 * If we are the delayed_rsv then push to the global rsv, otherwise dump
285 * into the delayed rsv if it is not full.
287 if (block_rsv
== delayed_rsv
)
289 else if (block_rsv
!= global_rsv
&& !delayed_rsv
->full
)
290 target
= delayed_rsv
;
292 if (target
&& block_rsv
->space_info
!= target
->space_info
)
295 return block_rsv_release_bytes(fs_info
, block_rsv
, target
, num_bytes
,
299 int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv
*block_rsv
, u64 num_bytes
)
303 spin_lock(&block_rsv
->lock
);
304 if (block_rsv
->reserved
>= num_bytes
) {
305 block_rsv
->reserved
-= num_bytes
;
306 if (block_rsv
->reserved
< block_rsv
->size
)
310 spin_unlock(&block_rsv
->lock
);
314 void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv
*block_rsv
,
315 u64 num_bytes
, bool update_size
)
317 spin_lock(&block_rsv
->lock
);
318 block_rsv
->reserved
+= num_bytes
;
320 block_rsv
->size
+= num_bytes
;
321 else if (block_rsv
->reserved
>= block_rsv
->size
)
323 spin_unlock(&block_rsv
->lock
);
326 int btrfs_cond_migrate_bytes(struct btrfs_fs_info
*fs_info
,
327 struct btrfs_block_rsv
*dest
, u64 num_bytes
,
330 struct btrfs_block_rsv
*global_rsv
= &fs_info
->global_block_rsv
;
333 if (global_rsv
->space_info
!= dest
->space_info
)
336 spin_lock(&global_rsv
->lock
);
337 min_bytes
= div_factor(global_rsv
->size
, min_factor
);
338 if (global_rsv
->reserved
< min_bytes
+ num_bytes
) {
339 spin_unlock(&global_rsv
->lock
);
342 global_rsv
->reserved
-= num_bytes
;
343 if (global_rsv
->reserved
< global_rsv
->size
)
344 global_rsv
->full
= 0;
345 spin_unlock(&global_rsv
->lock
);
347 btrfs_block_rsv_add_bytes(dest
, num_bytes
, true);
351 void btrfs_update_global_block_rsv(struct btrfs_fs_info
*fs_info
)
353 struct btrfs_block_rsv
*block_rsv
= &fs_info
->global_block_rsv
;
354 struct btrfs_space_info
*sinfo
= block_rsv
->space_info
;
355 struct btrfs_root
*root
, *tmp
;
356 u64 num_bytes
= btrfs_root_used(&fs_info
->tree_root
->root_item
);
357 unsigned int min_items
= 1;
360 * The global block rsv is based on the size of the extent tree, the
361 * checksum tree and the root tree. If the fs is empty we want to set
362 * it to a minimal amount for safety.
364 * We also are going to need to modify the minimum of the tree root and
365 * any global roots we could touch.
367 read_lock(&fs_info
->global_root_lock
);
368 rbtree_postorder_for_each_entry_safe(root
, tmp
, &fs_info
->global_root_tree
,
370 if (root
->root_key
.objectid
== BTRFS_EXTENT_TREE_OBJECTID
||
371 root
->root_key
.objectid
== BTRFS_CSUM_TREE_OBJECTID
||
372 root
->root_key
.objectid
== BTRFS_FREE_SPACE_TREE_OBJECTID
) {
373 num_bytes
+= btrfs_root_used(&root
->root_item
);
377 read_unlock(&fs_info
->global_root_lock
);
380 * But we also want to reserve enough space so we can do the fallback
381 * global reserve for an unlink, which is an additional 5 items (see the
382 * comment in __unlink_start_trans for what we're modifying.)
384 * But we also need space for the delayed ref updates from the unlink,
385 * so its 10, 5 for the actual operation, and 5 for the delayed ref
390 num_bytes
= max_t(u64
, num_bytes
,
391 btrfs_calc_insert_metadata_size(fs_info
, min_items
));
393 spin_lock(&sinfo
->lock
);
394 spin_lock(&block_rsv
->lock
);
396 block_rsv
->size
= min_t(u64
, num_bytes
, SZ_512M
);
398 if (block_rsv
->reserved
< block_rsv
->size
) {
399 num_bytes
= block_rsv
->size
- block_rsv
->reserved
;
400 btrfs_space_info_update_bytes_may_use(fs_info
, sinfo
,
402 block_rsv
->reserved
= block_rsv
->size
;
403 } else if (block_rsv
->reserved
> block_rsv
->size
) {
404 num_bytes
= block_rsv
->reserved
- block_rsv
->size
;
405 btrfs_space_info_update_bytes_may_use(fs_info
, sinfo
,
407 block_rsv
->reserved
= block_rsv
->size
;
408 btrfs_try_granting_tickets(fs_info
, sinfo
);
411 if (block_rsv
->reserved
== block_rsv
->size
)
416 if (block_rsv
->size
>= sinfo
->total_bytes
)
417 sinfo
->force_alloc
= CHUNK_ALLOC_FORCE
;
418 spin_unlock(&block_rsv
->lock
);
419 spin_unlock(&sinfo
->lock
);
422 void btrfs_init_root_block_rsv(struct btrfs_root
*root
)
424 struct btrfs_fs_info
*fs_info
= root
->fs_info
;
426 switch (root
->root_key
.objectid
) {
427 case BTRFS_CSUM_TREE_OBJECTID
:
428 case BTRFS_EXTENT_TREE_OBJECTID
:
429 case BTRFS_FREE_SPACE_TREE_OBJECTID
:
430 root
->block_rsv
= &fs_info
->delayed_refs_rsv
;
432 case BTRFS_ROOT_TREE_OBJECTID
:
433 case BTRFS_DEV_TREE_OBJECTID
:
434 case BTRFS_QUOTA_TREE_OBJECTID
:
435 root
->block_rsv
= &fs_info
->global_block_rsv
;
437 case BTRFS_CHUNK_TREE_OBJECTID
:
438 root
->block_rsv
= &fs_info
->chunk_block_rsv
;
441 root
->block_rsv
= NULL
;
446 void btrfs_init_global_block_rsv(struct btrfs_fs_info
*fs_info
)
448 struct btrfs_space_info
*space_info
;
450 space_info
= btrfs_find_space_info(fs_info
, BTRFS_BLOCK_GROUP_SYSTEM
);
451 fs_info
->chunk_block_rsv
.space_info
= space_info
;
453 space_info
= btrfs_find_space_info(fs_info
, BTRFS_BLOCK_GROUP_METADATA
);
454 fs_info
->global_block_rsv
.space_info
= space_info
;
455 fs_info
->trans_block_rsv
.space_info
= space_info
;
456 fs_info
->empty_block_rsv
.space_info
= space_info
;
457 fs_info
->delayed_block_rsv
.space_info
= space_info
;
458 fs_info
->delayed_refs_rsv
.space_info
= space_info
;
460 btrfs_update_global_block_rsv(fs_info
);
463 void btrfs_release_global_block_rsv(struct btrfs_fs_info
*fs_info
)
465 btrfs_block_rsv_release(fs_info
, &fs_info
->global_block_rsv
, (u64
)-1,
467 WARN_ON(fs_info
->trans_block_rsv
.size
> 0);
468 WARN_ON(fs_info
->trans_block_rsv
.reserved
> 0);
469 WARN_ON(fs_info
->chunk_block_rsv
.size
> 0);
470 WARN_ON(fs_info
->chunk_block_rsv
.reserved
> 0);
471 WARN_ON(fs_info
->delayed_block_rsv
.size
> 0);
472 WARN_ON(fs_info
->delayed_block_rsv
.reserved
> 0);
473 WARN_ON(fs_info
->delayed_refs_rsv
.reserved
> 0);
474 WARN_ON(fs_info
->delayed_refs_rsv
.size
> 0);
477 static struct btrfs_block_rsv
*get_block_rsv(
478 const struct btrfs_trans_handle
*trans
,
479 const struct btrfs_root
*root
)
481 struct btrfs_fs_info
*fs_info
= root
->fs_info
;
482 struct btrfs_block_rsv
*block_rsv
= NULL
;
484 if (test_bit(BTRFS_ROOT_SHAREABLE
, &root
->state
) ||
485 (root
== fs_info
->uuid_root
) ||
486 (trans
->adding_csums
&&
487 root
->root_key
.objectid
== BTRFS_CSUM_TREE_OBJECTID
))
488 block_rsv
= trans
->block_rsv
;
491 block_rsv
= root
->block_rsv
;
494 block_rsv
= &fs_info
->empty_block_rsv
;
499 struct btrfs_block_rsv
*btrfs_use_block_rsv(struct btrfs_trans_handle
*trans
,
500 struct btrfs_root
*root
,
503 struct btrfs_fs_info
*fs_info
= root
->fs_info
;
504 struct btrfs_block_rsv
*block_rsv
;
505 struct btrfs_block_rsv
*global_rsv
= &fs_info
->global_block_rsv
;
507 bool global_updated
= false;
509 block_rsv
= get_block_rsv(trans
, root
);
511 if (unlikely(block_rsv
->size
== 0))
514 ret
= btrfs_block_rsv_use_bytes(block_rsv
, blocksize
);
518 if (block_rsv
->failfast
)
521 if (block_rsv
->type
== BTRFS_BLOCK_RSV_GLOBAL
&& !global_updated
) {
522 global_updated
= true;
523 btrfs_update_global_block_rsv(fs_info
);
528 * The global reserve still exists to save us from ourselves, so don't
529 * warn_on if we are short on our delayed refs reserve.
531 if (block_rsv
->type
!= BTRFS_BLOCK_RSV_DELREFS
&&
532 btrfs_test_opt(fs_info
, ENOSPC_DEBUG
)) {
533 static DEFINE_RATELIMIT_STATE(_rs
,
534 DEFAULT_RATELIMIT_INTERVAL
* 10,
535 /*DEFAULT_RATELIMIT_BURST*/ 1);
536 if (__ratelimit(&_rs
))
538 "BTRFS: block rsv %d returned %d\n",
539 block_rsv
->type
, ret
);
542 ret
= btrfs_reserve_metadata_bytes(fs_info
, block_rsv
, blocksize
,
543 BTRFS_RESERVE_NO_FLUSH
);
547 * If we couldn't reserve metadata bytes try and use some from
548 * the global reserve if its space type is the same as the global
551 if (block_rsv
->type
!= BTRFS_BLOCK_RSV_GLOBAL
&&
552 block_rsv
->space_info
== global_rsv
->space_info
) {
553 ret
= btrfs_block_rsv_use_bytes(global_rsv
, blocksize
);