1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include "misc.h"
4 #include "ctree.h"
5 #include "block-rsv.h"
6 #include "space-info.h"
7 #include "transaction.h"
8 #include "block-group.h"
9 #include "disk-io.h"
10 
11 /*
12  * HOW DO BLOCK RESERVES WORK
13  *
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.
18  *
19  *   ->failfast exists for the truncate case, and is described below.
20  *
21  * NORMAL OPERATION
22  *
23  *   -> Reserve
24  *     Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
25  *
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.
29  *
30  *     ->size is an over-estimation of how much we may use for a particular
31  *     operation.
32  *
33  *   -> Use
34  *     Entrance: btrfs_use_block_rsv
35  *
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.
40  *
41  *   -> Finish
42  *     Entrance: btrfs_block_rsv_release
43  *
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.
47  *
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.
51  *
52  * TYPES OF BLOCK RESERVES
53  *
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).
58  *
59  * BLOCK_RSV_GLOBAL
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.
64  *
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.
67  *
68  * BLOCK_RSV_DELALLOC
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.
74  *
75  * BLOCK_RSV_DELREFS
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.
81  *
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.
86  *
87  * BLOCK_RSV_EMPTY
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.
92  *
93  * BLOCK_RSV_TEMP
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
100  *   re-reserve.
101  */
102 
block_rsv_release_bytes(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * block_rsv,struct btrfs_block_rsv * dest,u64 num_bytes,u64 * qgroup_to_release_ret)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)
107 {
108 	struct btrfs_space_info *space_info = block_rsv->space_info;
109 	u64 qgroup_to_release = 0;
110 	u64 ret;
111 
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;
116 	}
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;
121 		block_rsv->full = true;
122 	} else {
123 		num_bytes = 0;
124 	}
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;
129 	} else {
130 		qgroup_to_release = 0;
131 	}
132 	spin_unlock(&block_rsv->lock);
133 
134 	ret = num_bytes;
135 	if (num_bytes > 0) {
136 		if (dest) {
137 			spin_lock(&dest->lock);
138 			if (!dest->full) {
139 				u64 bytes_to_add;
140 
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)
145 					dest->full = true;
146 				num_bytes -= bytes_to_add;
147 			}
148 			spin_unlock(&dest->lock);
149 		}
150 		if (num_bytes)
151 			btrfs_space_info_free_bytes_may_use(fs_info,
152 							    space_info,
153 							    num_bytes);
154 	}
155 	if (qgroup_to_release_ret)
156 		*qgroup_to_release_ret = qgroup_to_release;
157 	return ret;
158 }
159 
btrfs_block_rsv_migrate(struct btrfs_block_rsv * src,struct btrfs_block_rsv * dst,u64 num_bytes,bool update_size)160 int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
161 			    struct btrfs_block_rsv *dst, u64 num_bytes,
162 			    bool update_size)
163 {
164 	int ret;
165 
166 	ret = btrfs_block_rsv_use_bytes(src, num_bytes);
167 	if (ret)
168 		return ret;
169 
170 	btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
171 	return 0;
172 }
173 
btrfs_init_block_rsv(struct btrfs_block_rsv * rsv,enum btrfs_rsv_type type)174 void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, enum btrfs_rsv_type type)
175 {
176 	memset(rsv, 0, sizeof(*rsv));
177 	spin_lock_init(&rsv->lock);
178 	rsv->type = type;
179 }
180 
btrfs_init_metadata_block_rsv(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * rsv,enum btrfs_rsv_type type)181 void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,
182 				   struct btrfs_block_rsv *rsv,
183 				   enum btrfs_rsv_type type)
184 {
185 	btrfs_init_block_rsv(rsv, type);
186 	rsv->space_info = btrfs_find_space_info(fs_info,
187 					    BTRFS_BLOCK_GROUP_METADATA);
188 }
189 
btrfs_alloc_block_rsv(struct btrfs_fs_info * fs_info,enum btrfs_rsv_type type)190 struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
191 					      enum btrfs_rsv_type type)
192 {
193 	struct btrfs_block_rsv *block_rsv;
194 
195 	block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
196 	if (!block_rsv)
197 		return NULL;
198 
199 	btrfs_init_metadata_block_rsv(fs_info, block_rsv, type);
200 	return block_rsv;
201 }
202 
btrfs_free_block_rsv(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * rsv)203 void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
204 			  struct btrfs_block_rsv *rsv)
205 {
206 	if (!rsv)
207 		return;
208 	btrfs_block_rsv_release(fs_info, rsv, (u64)-1, NULL);
209 	kfree(rsv);
210 }
211 
btrfs_block_rsv_add(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * block_rsv,u64 num_bytes,enum btrfs_reserve_flush_enum flush)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)
215 {
216 	int ret;
217 
218 	if (num_bytes == 0)
219 		return 0;
220 
221 	ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, num_bytes, flush);
222 	if (!ret)
223 		btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
224 
225 	return ret;
226 }
227 
btrfs_block_rsv_check(struct btrfs_block_rsv * block_rsv,int min_factor)228 int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
229 {
230 	u64 num_bytes = 0;
231 	int ret = -ENOSPC;
232 
233 	if (!block_rsv)
234 		return 0;
235 
236 	spin_lock(&block_rsv->lock);
237 	num_bytes = div_factor(block_rsv->size, min_factor);
238 	if (block_rsv->reserved >= num_bytes)
239 		ret = 0;
240 	spin_unlock(&block_rsv->lock);
241 
242 	return ret;
243 }
244 
btrfs_block_rsv_refill(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * block_rsv,u64 min_reserved,enum btrfs_reserve_flush_enum flush)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)
248 {
249 	u64 num_bytes = 0;
250 	int ret = -ENOSPC;
251 
252 	if (!block_rsv)
253 		return 0;
254 
255 	spin_lock(&block_rsv->lock);
256 	num_bytes = min_reserved;
257 	if (block_rsv->reserved >= num_bytes)
258 		ret = 0;
259 	else
260 		num_bytes -= block_rsv->reserved;
261 	spin_unlock(&block_rsv->lock);
262 
263 	if (!ret)
264 		return 0;
265 
266 	ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, num_bytes, flush);
267 	if (!ret) {
268 		btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
269 		return 0;
270 	}
271 
272 	return ret;
273 }
274 
btrfs_block_rsv_release(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * block_rsv,u64 num_bytes,u64 * qgroup_to_release)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)
278 {
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;
282 
283 	/*
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.
286 	 */
287 	if (block_rsv == delayed_rsv)
288 		target = global_rsv;
289 	else if (block_rsv != global_rsv && !btrfs_block_rsv_full(delayed_rsv))
290 		target = delayed_rsv;
291 
292 	if (target && block_rsv->space_info != target->space_info)
293 		target = NULL;
294 
295 	return block_rsv_release_bytes(fs_info, block_rsv, target, num_bytes,
296 				       qgroup_to_release);
297 }
298 
btrfs_block_rsv_use_bytes(struct btrfs_block_rsv * block_rsv,u64 num_bytes)299 int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv, u64 num_bytes)
300 {
301 	int ret = -ENOSPC;
302 
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)
307 			block_rsv->full = false;
308 		ret = 0;
309 	}
310 	spin_unlock(&block_rsv->lock);
311 	return ret;
312 }
313 
btrfs_block_rsv_add_bytes(struct btrfs_block_rsv * block_rsv,u64 num_bytes,bool update_size)314 void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
315 			       u64 num_bytes, bool update_size)
316 {
317 	spin_lock(&block_rsv->lock);
318 	block_rsv->reserved += num_bytes;
319 	if (update_size)
320 		block_rsv->size += num_bytes;
321 	else if (block_rsv->reserved >= block_rsv->size)
322 		block_rsv->full = true;
323 	spin_unlock(&block_rsv->lock);
324 }
325 
btrfs_cond_migrate_bytes(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * dest,u64 num_bytes,int min_factor)326 int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
327 			     struct btrfs_block_rsv *dest, u64 num_bytes,
328 			     int min_factor)
329 {
330 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
331 	u64 min_bytes;
332 
333 	if (global_rsv->space_info != dest->space_info)
334 		return -ENOSPC;
335 
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);
340 		return -ENOSPC;
341 	}
342 	global_rsv->reserved -= num_bytes;
343 	if (global_rsv->reserved < global_rsv->size)
344 		global_rsv->full = false;
345 	spin_unlock(&global_rsv->lock);
346 
347 	btrfs_block_rsv_add_bytes(dest, num_bytes, true);
348 	return 0;
349 }
350 
btrfs_update_global_block_rsv(struct btrfs_fs_info * fs_info)351 void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
352 {
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;
358 
359 	/*
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.
363 	 *
364 	 * We also are going to need to modify the minimum of the tree root and
365 	 * any global roots we could touch.
366 	 */
367 	read_lock(&fs_info->global_root_lock);
368 	rbtree_postorder_for_each_entry_safe(root, tmp, &fs_info->global_root_tree,
369 					     rb_node) {
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);
374 			min_items++;
375 		}
376 	}
377 	read_unlock(&fs_info->global_root_lock);
378 
379 	/*
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.)
383 	 *
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
386 	 * updates.
387 	 */
388 	min_items += 10;
389 
390 	num_bytes = max_t(u64, num_bytes,
391 			  btrfs_calc_insert_metadata_size(fs_info, min_items));
392 
393 	spin_lock(&sinfo->lock);
394 	spin_lock(&block_rsv->lock);
395 
396 	block_rsv->size = min_t(u64, num_bytes, SZ_512M);
397 
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,
401 						      num_bytes);
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,
406 						      -num_bytes);
407 		block_rsv->reserved = block_rsv->size;
408 		btrfs_try_granting_tickets(fs_info, sinfo);
409 	}
410 
411 	block_rsv->full = (block_rsv->reserved == block_rsv->size);
412 
413 	if (block_rsv->size >= sinfo->total_bytes)
414 		sinfo->force_alloc = CHUNK_ALLOC_FORCE;
415 	spin_unlock(&block_rsv->lock);
416 	spin_unlock(&sinfo->lock);
417 }
418 
btrfs_init_root_block_rsv(struct btrfs_root * root)419 void btrfs_init_root_block_rsv(struct btrfs_root *root)
420 {
421 	struct btrfs_fs_info *fs_info = root->fs_info;
422 
423 	switch (root->root_key.objectid) {
424 	case BTRFS_CSUM_TREE_OBJECTID:
425 	case BTRFS_EXTENT_TREE_OBJECTID:
426 	case BTRFS_FREE_SPACE_TREE_OBJECTID:
427 	case BTRFS_BLOCK_GROUP_TREE_OBJECTID:
428 		root->block_rsv = &fs_info->delayed_refs_rsv;
429 		break;
430 	case BTRFS_ROOT_TREE_OBJECTID:
431 	case BTRFS_DEV_TREE_OBJECTID:
432 	case BTRFS_QUOTA_TREE_OBJECTID:
433 		root->block_rsv = &fs_info->global_block_rsv;
434 		break;
435 	case BTRFS_CHUNK_TREE_OBJECTID:
436 		root->block_rsv = &fs_info->chunk_block_rsv;
437 		break;
438 	default:
439 		root->block_rsv = NULL;
440 		break;
441 	}
442 }
443 
btrfs_init_global_block_rsv(struct btrfs_fs_info * fs_info)444 void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
445 {
446 	struct btrfs_space_info *space_info;
447 
448 	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
449 	fs_info->chunk_block_rsv.space_info = space_info;
450 
451 	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
452 	fs_info->global_block_rsv.space_info = space_info;
453 	fs_info->trans_block_rsv.space_info = space_info;
454 	fs_info->empty_block_rsv.space_info = space_info;
455 	fs_info->delayed_block_rsv.space_info = space_info;
456 	fs_info->delayed_refs_rsv.space_info = space_info;
457 
458 	btrfs_update_global_block_rsv(fs_info);
459 }
460 
btrfs_release_global_block_rsv(struct btrfs_fs_info * fs_info)461 void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
462 {
463 	btrfs_block_rsv_release(fs_info, &fs_info->global_block_rsv, (u64)-1,
464 				NULL);
465 	WARN_ON(fs_info->trans_block_rsv.size > 0);
466 	WARN_ON(fs_info->trans_block_rsv.reserved > 0);
467 	WARN_ON(fs_info->chunk_block_rsv.size > 0);
468 	WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
469 	WARN_ON(fs_info->delayed_block_rsv.size > 0);
470 	WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
471 	WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
472 	WARN_ON(fs_info->delayed_refs_rsv.size > 0);
473 }
474 
get_block_rsv(const struct btrfs_trans_handle * trans,const struct btrfs_root * root)475 static struct btrfs_block_rsv *get_block_rsv(
476 					const struct btrfs_trans_handle *trans,
477 					const struct btrfs_root *root)
478 {
479 	struct btrfs_fs_info *fs_info = root->fs_info;
480 	struct btrfs_block_rsv *block_rsv = NULL;
481 
482 	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
483 	    (root == fs_info->uuid_root) ||
484 	    (trans->adding_csums &&
485 	     root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID))
486 		block_rsv = trans->block_rsv;
487 
488 	if (!block_rsv)
489 		block_rsv = root->block_rsv;
490 
491 	if (!block_rsv)
492 		block_rsv = &fs_info->empty_block_rsv;
493 
494 	return block_rsv;
495 }
496 
btrfs_use_block_rsv(struct btrfs_trans_handle * trans,struct btrfs_root * root,u32 blocksize)497 struct btrfs_block_rsv *btrfs_use_block_rsv(struct btrfs_trans_handle *trans,
498 					    struct btrfs_root *root,
499 					    u32 blocksize)
500 {
501 	struct btrfs_fs_info *fs_info = root->fs_info;
502 	struct btrfs_block_rsv *block_rsv;
503 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
504 	int ret;
505 	bool global_updated = false;
506 
507 	block_rsv = get_block_rsv(trans, root);
508 
509 	if (unlikely(block_rsv->size == 0))
510 		goto try_reserve;
511 again:
512 	ret = btrfs_block_rsv_use_bytes(block_rsv, blocksize);
513 	if (!ret)
514 		return block_rsv;
515 
516 	if (block_rsv->failfast)
517 		return ERR_PTR(ret);
518 
519 	if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
520 		global_updated = true;
521 		btrfs_update_global_block_rsv(fs_info);
522 		goto again;
523 	}
524 
525 	/*
526 	 * The global reserve still exists to save us from ourselves, so don't
527 	 * warn_on if we are short on our delayed refs reserve.
528 	 */
529 	if (block_rsv->type != BTRFS_BLOCK_RSV_DELREFS &&
530 	    btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
531 		static DEFINE_RATELIMIT_STATE(_rs,
532 				DEFAULT_RATELIMIT_INTERVAL * 10,
533 				/*DEFAULT_RATELIMIT_BURST*/ 1);
534 		if (__ratelimit(&_rs))
535 			WARN(1, KERN_DEBUG
536 				"BTRFS: block rsv %d returned %d\n",
537 				block_rsv->type, ret);
538 	}
539 try_reserve:
540 	ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, blocksize,
541 					   BTRFS_RESERVE_NO_FLUSH);
542 	if (!ret)
543 		return block_rsv;
544 	/*
545 	 * If we couldn't reserve metadata bytes try and use some from
546 	 * the global reserve if its space type is the same as the global
547 	 * reservation.
548 	 */
549 	if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
550 	    block_rsv->space_info == global_rsv->space_info) {
551 		ret = btrfs_block_rsv_use_bytes(global_rsv, blocksize);
552 		if (!ret)
553 			return global_rsv;
554 	}
555 	return ERR_PTR(ret);
556 }
557