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 #include "zoned.h"
13 
14 /*
15  * HOW DOES SPACE RESERVATION WORK
16  *
17  * If you want to know about delalloc specifically, there is a separate comment
18  * for that with the delalloc code.  This comment is about how the whole system
19  * works generally.
20  *
21  * BASIC CONCEPTS
22  *
23  *   1) space_info.  This is the ultimate arbiter of how much space we can use.
24  *   There's a description of the bytes_ fields with the struct declaration,
25  *   refer to that for specifics on each field.  Suffice it to say that for
26  *   reservations we care about total_bytes - SUM(space_info->bytes_) when
27  *   determining if there is space to make an allocation.  There is a space_info
28  *   for METADATA, SYSTEM, and DATA areas.
29  *
30  *   2) block_rsv's.  These are basically buckets for every different type of
31  *   metadata reservation we have.  You can see the comment in the block_rsv
32  *   code on the rules for each type, but generally block_rsv->reserved is how
33  *   much space is accounted for in space_info->bytes_may_use.
34  *
35  *   3) btrfs_calc*_size.  These are the worst case calculations we used based
36  *   on the number of items we will want to modify.  We have one for changing
37  *   items, and one for inserting new items.  Generally we use these helpers to
38  *   determine the size of the block reserves, and then use the actual bytes
39  *   values to adjust the space_info counters.
40  *
41  * MAKING RESERVATIONS, THE NORMAL CASE
42  *
43  *   We call into either btrfs_reserve_data_bytes() or
44  *   btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
45  *   num_bytes we want to reserve.
46  *
47  *   ->reserve
48  *     space_info->bytes_may_reserve += num_bytes
49  *
50  *   ->extent allocation
51  *     Call btrfs_add_reserved_bytes() which does
52  *     space_info->bytes_may_reserve -= num_bytes
53  *     space_info->bytes_reserved += extent_bytes
54  *
55  *   ->insert reference
56  *     Call btrfs_update_block_group() which does
57  *     space_info->bytes_reserved -= extent_bytes
58  *     space_info->bytes_used += extent_bytes
59  *
60  * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
61  *
62  *   Assume we are unable to simply make the reservation because we do not have
63  *   enough space
64  *
65  *   -> __reserve_bytes
66  *     create a reserve_ticket with ->bytes set to our reservation, add it to
67  *     the tail of space_info->tickets, kick async flush thread
68  *
69  *   ->handle_reserve_ticket
70  *     wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
71  *     on the ticket.
72  *
73  *   -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
74  *     Flushes various things attempting to free up space.
75  *
76  *   -> btrfs_try_granting_tickets()
77  *     This is called by anything that either subtracts space from
78  *     space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
79  *     space_info->total_bytes.  This loops through the ->priority_tickets and
80  *     then the ->tickets list checking to see if the reservation can be
81  *     completed.  If it can the space is added to space_info->bytes_may_use and
82  *     the ticket is woken up.
83  *
84  *   -> ticket wakeup
85  *     Check if ->bytes == 0, if it does we got our reservation and we can carry
86  *     on, if not return the appropriate error (ENOSPC, but can be EINTR if we
87  *     were interrupted.)
88  *
89  * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
90  *
91  *   Same as the above, except we add ourselves to the
92  *   space_info->priority_tickets, and we do not use ticket->wait, we simply
93  *   call flush_space() ourselves for the states that are safe for us to call
94  *   without deadlocking and hope for the best.
95  *
96  * THE FLUSHING STATES
97  *
98  *   Generally speaking we will have two cases for each state, a "nice" state
99  *   and a "ALL THE THINGS" state.  In btrfs we delay a lot of work in order to
100  *   reduce the locking over head on the various trees, and even to keep from
101  *   doing any work at all in the case of delayed refs.  Each of these delayed
102  *   things however hold reservations, and so letting them run allows us to
103  *   reclaim space so we can make new reservations.
104  *
105  *   FLUSH_DELAYED_ITEMS
106  *     Every inode has a delayed item to update the inode.  Take a simple write
107  *     for example, we would update the inode item at write time to update the
108  *     mtime, and then again at finish_ordered_io() time in order to update the
109  *     isize or bytes.  We keep these delayed items to coalesce these operations
110  *     into a single operation done on demand.  These are an easy way to reclaim
111  *     metadata space.
112  *
113  *   FLUSH_DELALLOC
114  *     Look at the delalloc comment to get an idea of how much space is reserved
115  *     for delayed allocation.  We can reclaim some of this space simply by
116  *     running delalloc, but usually we need to wait for ordered extents to
117  *     reclaim the bulk of this space.
118  *
119  *   FLUSH_DELAYED_REFS
120  *     We have a block reserve for the outstanding delayed refs space, and every
121  *     delayed ref operation holds a reservation.  Running these is a quick way
122  *     to reclaim space, but we want to hold this until the end because COW can
123  *     churn a lot and we can avoid making some extent tree modifications if we
124  *     are able to delay for as long as possible.
125  *
126  *   ALLOC_CHUNK
127  *     We will skip this the first time through space reservation, because of
128  *     overcommit and we don't want to have a lot of useless metadata space when
129  *     our worst case reservations will likely never come true.
130  *
131  *   RUN_DELAYED_IPUTS
132  *     If we're freeing inodes we're likely freeing checksums, file extent
133  *     items, and extent tree items.  Loads of space could be freed up by these
134  *     operations, however they won't be usable until the transaction commits.
135  *
136  *   COMMIT_TRANS
137  *     This will commit the transaction.  Historically we had a lot of logic
138  *     surrounding whether or not we'd commit the transaction, but this waits born
139  *     out of a pre-tickets era where we could end up committing the transaction
140  *     thousands of times in a row without making progress.  Now thanks to our
141  *     ticketing system we know if we're not making progress and can error
142  *     everybody out after a few commits rather than burning the disk hoping for
143  *     a different answer.
144  *
145  * OVERCOMMIT
146  *
147  *   Because we hold so many reservations for metadata we will allow you to
148  *   reserve more space than is currently free in the currently allocate
149  *   metadata space.  This only happens with metadata, data does not allow
150  *   overcommitting.
151  *
152  *   You can see the current logic for when we allow overcommit in
153  *   btrfs_can_overcommit(), but it only applies to unallocated space.  If there
154  *   is no unallocated space to be had, all reservations are kept within the
155  *   free space in the allocated metadata chunks.
156  *
157  *   Because of overcommitting, you generally want to use the
158  *   btrfs_can_overcommit() logic for metadata allocations, as it does the right
159  *   thing with or without extra unallocated space.
160  */
161 
btrfs_space_info_used(struct btrfs_space_info * s_info,bool may_use_included)162 u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
163 			  bool may_use_included)
164 {
165 	ASSERT(s_info);
166 	return s_info->bytes_used + s_info->bytes_reserved +
167 		s_info->bytes_pinned + s_info->bytes_readonly +
168 		s_info->bytes_zone_unusable +
169 		(may_use_included ? s_info->bytes_may_use : 0);
170 }
171 
172 /*
173  * after adding space to the filesystem, we need to clear the full flags
174  * on all the space infos.
175  */
btrfs_clear_space_info_full(struct btrfs_fs_info * info)176 void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
177 {
178 	struct list_head *head = &info->space_info;
179 	struct btrfs_space_info *found;
180 
181 	list_for_each_entry(found, head, list)
182 		found->full = 0;
183 }
184 
185 /*
186  * Block groups with more than this value (percents) of unusable space will be
187  * scheduled for background reclaim.
188  */
189 #define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH			(75)
190 
191 /*
192  * Calculate chunk size depending on volume type (regular or zoned).
193  */
calc_chunk_size(const struct btrfs_fs_info * fs_info,u64 flags)194 static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
195 {
196 	if (btrfs_is_zoned(fs_info))
197 		return fs_info->zone_size;
198 
199 	ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
200 
201 	if (flags & BTRFS_BLOCK_GROUP_DATA)
202 		return BTRFS_MAX_DATA_CHUNK_SIZE;
203 	else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
204 		return SZ_32M;
205 
206 	/* Handle BTRFS_BLOCK_GROUP_METADATA */
207 	if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
208 		return SZ_1G;
209 
210 	return SZ_256M;
211 }
212 
213 /*
214  * Update default chunk size.
215  */
btrfs_update_space_info_chunk_size(struct btrfs_space_info * space_info,u64 chunk_size)216 void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
217 					u64 chunk_size)
218 {
219 	WRITE_ONCE(space_info->chunk_size, chunk_size);
220 }
221 
create_space_info(struct btrfs_fs_info * info,u64 flags)222 static int create_space_info(struct btrfs_fs_info *info, u64 flags)
223 {
224 
225 	struct btrfs_space_info *space_info;
226 	int i;
227 	int ret;
228 
229 	space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
230 	if (!space_info)
231 		return -ENOMEM;
232 
233 	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
234 		INIT_LIST_HEAD(&space_info->block_groups[i]);
235 	init_rwsem(&space_info->groups_sem);
236 	spin_lock_init(&space_info->lock);
237 	space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
238 	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
239 	INIT_LIST_HEAD(&space_info->ro_bgs);
240 	INIT_LIST_HEAD(&space_info->tickets);
241 	INIT_LIST_HEAD(&space_info->priority_tickets);
242 	space_info->clamp = 1;
243 	btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags));
244 
245 	if (btrfs_is_zoned(info))
246 		space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH;
247 
248 	ret = btrfs_sysfs_add_space_info_type(info, space_info);
249 	if (ret)
250 		return ret;
251 
252 	list_add(&space_info->list, &info->space_info);
253 	if (flags & BTRFS_BLOCK_GROUP_DATA)
254 		info->data_sinfo = space_info;
255 
256 	return ret;
257 }
258 
btrfs_init_space_info(struct btrfs_fs_info * fs_info)259 int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
260 {
261 	struct btrfs_super_block *disk_super;
262 	u64 features;
263 	u64 flags;
264 	int mixed = 0;
265 	int ret;
266 
267 	disk_super = fs_info->super_copy;
268 	if (!btrfs_super_root(disk_super))
269 		return -EINVAL;
270 
271 	features = btrfs_super_incompat_flags(disk_super);
272 	if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
273 		mixed = 1;
274 
275 	flags = BTRFS_BLOCK_GROUP_SYSTEM;
276 	ret = create_space_info(fs_info, flags);
277 	if (ret)
278 		goto out;
279 
280 	if (mixed) {
281 		flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
282 		ret = create_space_info(fs_info, flags);
283 	} else {
284 		flags = BTRFS_BLOCK_GROUP_METADATA;
285 		ret = create_space_info(fs_info, flags);
286 		if (ret)
287 			goto out;
288 
289 		flags = BTRFS_BLOCK_GROUP_DATA;
290 		ret = create_space_info(fs_info, flags);
291 	}
292 out:
293 	return ret;
294 }
295 
btrfs_add_bg_to_space_info(struct btrfs_fs_info * info,struct btrfs_block_group * block_group)296 void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
297 				struct btrfs_block_group *block_group)
298 {
299 	struct btrfs_space_info *found;
300 	int factor, index;
301 
302 	factor = btrfs_bg_type_to_factor(block_group->flags);
303 
304 	found = btrfs_find_space_info(info, block_group->flags);
305 	ASSERT(found);
306 	spin_lock(&found->lock);
307 	found->total_bytes += block_group->length;
308 	if (test_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &block_group->runtime_flags))
309 		found->active_total_bytes += block_group->length;
310 	found->disk_total += block_group->length * factor;
311 	found->bytes_used += block_group->used;
312 	found->disk_used += block_group->used * factor;
313 	found->bytes_readonly += block_group->bytes_super;
314 	found->bytes_zone_unusable += block_group->zone_unusable;
315 	if (block_group->length > 0)
316 		found->full = 0;
317 	btrfs_try_granting_tickets(info, found);
318 	spin_unlock(&found->lock);
319 
320 	block_group->space_info = found;
321 
322 	index = btrfs_bg_flags_to_raid_index(block_group->flags);
323 	down_write(&found->groups_sem);
324 	list_add_tail(&block_group->list, &found->block_groups[index]);
325 	up_write(&found->groups_sem);
326 }
327 
btrfs_find_space_info(struct btrfs_fs_info * info,u64 flags)328 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
329 					       u64 flags)
330 {
331 	struct list_head *head = &info->space_info;
332 	struct btrfs_space_info *found;
333 
334 	flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
335 
336 	list_for_each_entry(found, head, list) {
337 		if (found->flags & flags)
338 			return found;
339 	}
340 	return NULL;
341 }
342 
calc_available_free_space(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,enum btrfs_reserve_flush_enum flush)343 static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
344 			  struct btrfs_space_info *space_info,
345 			  enum btrfs_reserve_flush_enum flush)
346 {
347 	u64 profile;
348 	u64 avail;
349 	int factor;
350 
351 	if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
352 		profile = btrfs_system_alloc_profile(fs_info);
353 	else
354 		profile = btrfs_metadata_alloc_profile(fs_info);
355 
356 	avail = atomic64_read(&fs_info->free_chunk_space);
357 
358 	/*
359 	 * If we have dup, raid1 or raid10 then only half of the free
360 	 * space is actually usable.  For raid56, the space info used
361 	 * doesn't include the parity drive, so we don't have to
362 	 * change the math
363 	 */
364 	factor = btrfs_bg_type_to_factor(profile);
365 	avail = div_u64(avail, factor);
366 
367 	/*
368 	 * If we aren't flushing all things, let us overcommit up to
369 	 * 1/2th of the space. If we can flush, don't let us overcommit
370 	 * too much, let it overcommit up to 1/8 of the space.
371 	 */
372 	if (flush == BTRFS_RESERVE_FLUSH_ALL)
373 		avail >>= 3;
374 	else
375 		avail >>= 1;
376 	return avail;
377 }
378 
writable_total_bytes(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)379 static inline u64 writable_total_bytes(struct btrfs_fs_info *fs_info,
380 				       struct btrfs_space_info *space_info)
381 {
382 	/*
383 	 * On regular filesystem, all total_bytes are always writable. On zoned
384 	 * filesystem, there may be a limitation imposed by max_active_zones.
385 	 * For metadata allocation, we cannot finish an existing active block
386 	 * group to avoid a deadlock. Thus, we need to consider only the active
387 	 * groups to be writable for metadata space.
388 	 */
389 	if (!btrfs_is_zoned(fs_info) || (space_info->flags & BTRFS_BLOCK_GROUP_DATA))
390 		return space_info->total_bytes;
391 
392 	return space_info->active_total_bytes;
393 }
394 
btrfs_can_overcommit(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,u64 bytes,enum btrfs_reserve_flush_enum flush)395 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
396 			 struct btrfs_space_info *space_info, u64 bytes,
397 			 enum btrfs_reserve_flush_enum flush)
398 {
399 	u64 avail;
400 	u64 used;
401 
402 	/* Don't overcommit when in mixed mode */
403 	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
404 		return 0;
405 
406 	used = btrfs_space_info_used(space_info, true);
407 	if (test_bit(BTRFS_FS_NO_OVERCOMMIT, &fs_info->flags) &&
408 	    (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))
409 		avail = 0;
410 	else
411 		avail = calc_available_free_space(fs_info, space_info, flush);
412 
413 	if (used + bytes < writable_total_bytes(fs_info, space_info) + avail)
414 		return 1;
415 	return 0;
416 }
417 
remove_ticket(struct btrfs_space_info * space_info,struct reserve_ticket * ticket)418 static void remove_ticket(struct btrfs_space_info *space_info,
419 			  struct reserve_ticket *ticket)
420 {
421 	if (!list_empty(&ticket->list)) {
422 		list_del_init(&ticket->list);
423 		ASSERT(space_info->reclaim_size >= ticket->bytes);
424 		space_info->reclaim_size -= ticket->bytes;
425 	}
426 }
427 
428 /*
429  * This is for space we already have accounted in space_info->bytes_may_use, so
430  * basically when we're returning space from block_rsv's.
431  */
btrfs_try_granting_tickets(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)432 void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
433 				struct btrfs_space_info *space_info)
434 {
435 	struct list_head *head;
436 	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
437 
438 	lockdep_assert_held(&space_info->lock);
439 
440 	head = &space_info->priority_tickets;
441 again:
442 	while (!list_empty(head)) {
443 		struct reserve_ticket *ticket;
444 		u64 used = btrfs_space_info_used(space_info, true);
445 
446 		ticket = list_first_entry(head, struct reserve_ticket, list);
447 
448 		/* Check and see if our ticket can be satisfied now. */
449 		if ((used + ticket->bytes <= writable_total_bytes(fs_info, space_info)) ||
450 		    btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
451 					 flush)) {
452 			btrfs_space_info_update_bytes_may_use(fs_info,
453 							      space_info,
454 							      ticket->bytes);
455 			remove_ticket(space_info, ticket);
456 			ticket->bytes = 0;
457 			space_info->tickets_id++;
458 			wake_up(&ticket->wait);
459 		} else {
460 			break;
461 		}
462 	}
463 
464 	if (head == &space_info->priority_tickets) {
465 		head = &space_info->tickets;
466 		flush = BTRFS_RESERVE_FLUSH_ALL;
467 		goto again;
468 	}
469 }
470 
471 #define DUMP_BLOCK_RSV(fs_info, rsv_name)				\
472 do {									\
473 	struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name;		\
474 	spin_lock(&__rsv->lock);					\
475 	btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu",	\
476 		   __rsv->size, __rsv->reserved);			\
477 	spin_unlock(&__rsv->lock);					\
478 } while (0)
479 
space_info_flag_to_str(const struct btrfs_space_info * space_info)480 static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info)
481 {
482 	switch (space_info->flags) {
483 	case BTRFS_BLOCK_GROUP_SYSTEM:
484 		return "SYSTEM";
485 	case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
486 		return "DATA+METADATA";
487 	case BTRFS_BLOCK_GROUP_DATA:
488 		return "DATA";
489 	case BTRFS_BLOCK_GROUP_METADATA:
490 		return "METADATA";
491 	default:
492 		return "UNKNOWN";
493 	}
494 }
495 
dump_global_block_rsv(struct btrfs_fs_info * fs_info)496 static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
497 {
498 	DUMP_BLOCK_RSV(fs_info, global_block_rsv);
499 	DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
500 	DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
501 	DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
502 	DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
503 }
504 
__btrfs_dump_space_info(struct btrfs_fs_info * fs_info,struct btrfs_space_info * info)505 static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
506 				    struct btrfs_space_info *info)
507 {
508 	const char *flag_str = space_info_flag_to_str(info);
509 	lockdep_assert_held(&info->lock);
510 
511 	/* The free space could be negative in case of overcommit */
512 	btrfs_info(fs_info, "space_info %s has %lld free, is %sfull",
513 		   flag_str,
514 		   (s64)(info->total_bytes - btrfs_space_info_used(info, true)),
515 		   info->full ? "" : "not ");
516 	btrfs_info(fs_info,
517 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
518 		info->total_bytes, info->bytes_used, info->bytes_pinned,
519 		info->bytes_reserved, info->bytes_may_use,
520 		info->bytes_readonly, info->bytes_zone_unusable);
521 }
522 
btrfs_dump_space_info(struct btrfs_fs_info * fs_info,struct btrfs_space_info * info,u64 bytes,int dump_block_groups)523 void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
524 			   struct btrfs_space_info *info, u64 bytes,
525 			   int dump_block_groups)
526 {
527 	struct btrfs_block_group *cache;
528 	int index = 0;
529 
530 	spin_lock(&info->lock);
531 	__btrfs_dump_space_info(fs_info, info);
532 	dump_global_block_rsv(fs_info);
533 	spin_unlock(&info->lock);
534 
535 	if (!dump_block_groups)
536 		return;
537 
538 	down_read(&info->groups_sem);
539 again:
540 	list_for_each_entry(cache, &info->block_groups[index], list) {
541 		spin_lock(&cache->lock);
542 		btrfs_info(fs_info,
543 			"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu zone_unusable %s",
544 			cache->start, cache->length, cache->used, cache->pinned,
545 			cache->reserved, cache->zone_unusable,
546 			cache->ro ? "[readonly]" : "");
547 		spin_unlock(&cache->lock);
548 		btrfs_dump_free_space(cache, bytes);
549 	}
550 	if (++index < BTRFS_NR_RAID_TYPES)
551 		goto again;
552 	up_read(&info->groups_sem);
553 }
554 
calc_reclaim_items_nr(struct btrfs_fs_info * fs_info,u64 to_reclaim)555 static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
556 					u64 to_reclaim)
557 {
558 	u64 bytes;
559 	u64 nr;
560 
561 	bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
562 	nr = div64_u64(to_reclaim, bytes);
563 	if (!nr)
564 		nr = 1;
565 	return nr;
566 }
567 
568 #define EXTENT_SIZE_PER_ITEM	SZ_256K
569 
570 /*
571  * shrink metadata reservation for delalloc
572  */
shrink_delalloc(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,u64 to_reclaim,bool wait_ordered,bool for_preempt)573 static void shrink_delalloc(struct btrfs_fs_info *fs_info,
574 			    struct btrfs_space_info *space_info,
575 			    u64 to_reclaim, bool wait_ordered,
576 			    bool for_preempt)
577 {
578 	struct btrfs_trans_handle *trans;
579 	u64 delalloc_bytes;
580 	u64 ordered_bytes;
581 	u64 items;
582 	long time_left;
583 	int loops;
584 
585 	delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
586 	ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
587 	if (delalloc_bytes == 0 && ordered_bytes == 0)
588 		return;
589 
590 	/* Calc the number of the pages we need flush for space reservation */
591 	if (to_reclaim == U64_MAX) {
592 		items = U64_MAX;
593 	} else {
594 		/*
595 		 * to_reclaim is set to however much metadata we need to
596 		 * reclaim, but reclaiming that much data doesn't really track
597 		 * exactly.  What we really want to do is reclaim full inode's
598 		 * worth of reservations, however that's not available to us
599 		 * here.  We will take a fraction of the delalloc bytes for our
600 		 * flushing loops and hope for the best.  Delalloc will expand
601 		 * the amount we write to cover an entire dirty extent, which
602 		 * will reclaim the metadata reservation for that range.  If
603 		 * it's not enough subsequent flush stages will be more
604 		 * aggressive.
605 		 */
606 		to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
607 		items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
608 	}
609 
610 	trans = current->journal_info;
611 
612 	/*
613 	 * If we are doing more ordered than delalloc we need to just wait on
614 	 * ordered extents, otherwise we'll waste time trying to flush delalloc
615 	 * that likely won't give us the space back we need.
616 	 */
617 	if (ordered_bytes > delalloc_bytes && !for_preempt)
618 		wait_ordered = true;
619 
620 	loops = 0;
621 	while ((delalloc_bytes || ordered_bytes) && loops < 3) {
622 		u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
623 		long nr_pages = min_t(u64, temp, LONG_MAX);
624 		int async_pages;
625 
626 		btrfs_start_delalloc_roots(fs_info, nr_pages, true);
627 
628 		/*
629 		 * We need to make sure any outstanding async pages are now
630 		 * processed before we continue.  This is because things like
631 		 * sync_inode() try to be smart and skip writing if the inode is
632 		 * marked clean.  We don't use filemap_fwrite for flushing
633 		 * because we want to control how many pages we write out at a
634 		 * time, thus this is the only safe way to make sure we've
635 		 * waited for outstanding compressed workers to have started
636 		 * their jobs and thus have ordered extents set up properly.
637 		 *
638 		 * This exists because we do not want to wait for each
639 		 * individual inode to finish its async work, we simply want to
640 		 * start the IO on everybody, and then come back here and wait
641 		 * for all of the async work to catch up.  Once we're done with
642 		 * that we know we'll have ordered extents for everything and we
643 		 * can decide if we wait for that or not.
644 		 *
645 		 * If we choose to replace this in the future, make absolutely
646 		 * sure that the proper waiting is being done in the async case,
647 		 * as there have been bugs in that area before.
648 		 */
649 		async_pages = atomic_read(&fs_info->async_delalloc_pages);
650 		if (!async_pages)
651 			goto skip_async;
652 
653 		/*
654 		 * We don't want to wait forever, if we wrote less pages in this
655 		 * loop than we have outstanding, only wait for that number of
656 		 * pages, otherwise we can wait for all async pages to finish
657 		 * before continuing.
658 		 */
659 		if (async_pages > nr_pages)
660 			async_pages -= nr_pages;
661 		else
662 			async_pages = 0;
663 		wait_event(fs_info->async_submit_wait,
664 			   atomic_read(&fs_info->async_delalloc_pages) <=
665 			   async_pages);
666 skip_async:
667 		loops++;
668 		if (wait_ordered && !trans) {
669 			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
670 		} else {
671 			time_left = schedule_timeout_killable(1);
672 			if (time_left)
673 				break;
674 		}
675 
676 		/*
677 		 * If we are for preemption we just want a one-shot of delalloc
678 		 * flushing so we can stop flushing if we decide we don't need
679 		 * to anymore.
680 		 */
681 		if (for_preempt)
682 			break;
683 
684 		spin_lock(&space_info->lock);
685 		if (list_empty(&space_info->tickets) &&
686 		    list_empty(&space_info->priority_tickets)) {
687 			spin_unlock(&space_info->lock);
688 			break;
689 		}
690 		spin_unlock(&space_info->lock);
691 
692 		delalloc_bytes = percpu_counter_sum_positive(
693 						&fs_info->delalloc_bytes);
694 		ordered_bytes = percpu_counter_sum_positive(
695 						&fs_info->ordered_bytes);
696 	}
697 }
698 
699 /*
700  * Try to flush some data based on policy set by @state. This is only advisory
701  * and may fail for various reasons. The caller is supposed to examine the
702  * state of @space_info to detect the outcome.
703  */
flush_space(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,u64 num_bytes,enum btrfs_flush_state state,bool for_preempt)704 static void flush_space(struct btrfs_fs_info *fs_info,
705 		       struct btrfs_space_info *space_info, u64 num_bytes,
706 		       enum btrfs_flush_state state, bool for_preempt)
707 {
708 	struct btrfs_root *root = fs_info->tree_root;
709 	struct btrfs_trans_handle *trans;
710 	int nr;
711 	int ret = 0;
712 
713 	switch (state) {
714 	case FLUSH_DELAYED_ITEMS_NR:
715 	case FLUSH_DELAYED_ITEMS:
716 		if (state == FLUSH_DELAYED_ITEMS_NR)
717 			nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
718 		else
719 			nr = -1;
720 
721 		trans = btrfs_join_transaction(root);
722 		if (IS_ERR(trans)) {
723 			ret = PTR_ERR(trans);
724 			break;
725 		}
726 		ret = btrfs_run_delayed_items_nr(trans, nr);
727 		btrfs_end_transaction(trans);
728 		break;
729 	case FLUSH_DELALLOC:
730 	case FLUSH_DELALLOC_WAIT:
731 	case FLUSH_DELALLOC_FULL:
732 		if (state == FLUSH_DELALLOC_FULL)
733 			num_bytes = U64_MAX;
734 		shrink_delalloc(fs_info, space_info, num_bytes,
735 				state != FLUSH_DELALLOC, for_preempt);
736 		break;
737 	case FLUSH_DELAYED_REFS_NR:
738 	case FLUSH_DELAYED_REFS:
739 		trans = btrfs_join_transaction(root);
740 		if (IS_ERR(trans)) {
741 			ret = PTR_ERR(trans);
742 			break;
743 		}
744 		if (state == FLUSH_DELAYED_REFS_NR)
745 			nr = calc_reclaim_items_nr(fs_info, num_bytes);
746 		else
747 			nr = 0;
748 		btrfs_run_delayed_refs(trans, nr);
749 		btrfs_end_transaction(trans);
750 		break;
751 	case ALLOC_CHUNK:
752 	case ALLOC_CHUNK_FORCE:
753 		/*
754 		 * For metadata space on zoned filesystem, reaching here means we
755 		 * don't have enough space left in active_total_bytes. Try to
756 		 * activate a block group first, because we may have inactive
757 		 * block group already allocated.
758 		 */
759 		ret = btrfs_zoned_activate_one_bg(fs_info, space_info, false);
760 		if (ret < 0)
761 			break;
762 		else if (ret == 1)
763 			break;
764 
765 		trans = btrfs_join_transaction(root);
766 		if (IS_ERR(trans)) {
767 			ret = PTR_ERR(trans);
768 			break;
769 		}
770 		ret = btrfs_chunk_alloc(trans,
771 				btrfs_get_alloc_profile(fs_info, space_info->flags),
772 				(state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
773 					CHUNK_ALLOC_FORCE);
774 		btrfs_end_transaction(trans);
775 
776 		/*
777 		 * For metadata space on zoned filesystem, allocating a new chunk
778 		 * is not enough. We still need to activate the block * group.
779 		 * Active the newly allocated block group by (maybe) finishing
780 		 * a block group.
781 		 */
782 		if (ret == 1) {
783 			ret = btrfs_zoned_activate_one_bg(fs_info, space_info, true);
784 			/*
785 			 * Revert to the original ret regardless we could finish
786 			 * one block group or not.
787 			 */
788 			if (ret >= 0)
789 				ret = 1;
790 		}
791 
792 		if (ret > 0 || ret == -ENOSPC)
793 			ret = 0;
794 		break;
795 	case RUN_DELAYED_IPUTS:
796 		/*
797 		 * If we have pending delayed iputs then we could free up a
798 		 * bunch of pinned space, so make sure we run the iputs before
799 		 * we do our pinned bytes check below.
800 		 */
801 		btrfs_run_delayed_iputs(fs_info);
802 		btrfs_wait_on_delayed_iputs(fs_info);
803 		break;
804 	case COMMIT_TRANS:
805 		ASSERT(current->journal_info == NULL);
806 		trans = btrfs_join_transaction(root);
807 		if (IS_ERR(trans)) {
808 			ret = PTR_ERR(trans);
809 			break;
810 		}
811 		ret = btrfs_commit_transaction(trans);
812 		break;
813 	default:
814 		ret = -ENOSPC;
815 		break;
816 	}
817 
818 	trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
819 				ret, for_preempt);
820 	return;
821 }
822 
823 static inline u64
btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)824 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
825 				 struct btrfs_space_info *space_info)
826 {
827 	u64 used;
828 	u64 avail;
829 	u64 total;
830 	u64 to_reclaim = space_info->reclaim_size;
831 
832 	lockdep_assert_held(&space_info->lock);
833 
834 	avail = calc_available_free_space(fs_info, space_info,
835 					  BTRFS_RESERVE_FLUSH_ALL);
836 	used = btrfs_space_info_used(space_info, true);
837 
838 	/*
839 	 * We may be flushing because suddenly we have less space than we had
840 	 * before, and now we're well over-committed based on our current free
841 	 * space.  If that's the case add in our overage so we make sure to put
842 	 * appropriate pressure on the flushing state machine.
843 	 */
844 	total = writable_total_bytes(fs_info, space_info);
845 	if (total + avail < used)
846 		to_reclaim += used - (total + avail);
847 
848 	return to_reclaim;
849 }
850 
need_preemptive_reclaim(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)851 static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
852 				    struct btrfs_space_info *space_info)
853 {
854 	u64 global_rsv_size = fs_info->global_block_rsv.reserved;
855 	u64 ordered, delalloc;
856 	u64 total = writable_total_bytes(fs_info, space_info);
857 	u64 thresh;
858 	u64 used;
859 
860 	thresh = div_factor_fine(total, 90);
861 
862 	lockdep_assert_held(&space_info->lock);
863 
864 	/* If we're just plain full then async reclaim just slows us down. */
865 	if ((space_info->bytes_used + space_info->bytes_reserved +
866 	     global_rsv_size) >= thresh)
867 		return false;
868 
869 	used = space_info->bytes_may_use + space_info->bytes_pinned;
870 
871 	/* The total flushable belongs to the global rsv, don't flush. */
872 	if (global_rsv_size >= used)
873 		return false;
874 
875 	/*
876 	 * 128MiB is 1/4 of the maximum global rsv size.  If we have less than
877 	 * that devoted to other reservations then there's no sense in flushing,
878 	 * we don't have a lot of things that need flushing.
879 	 */
880 	if (used - global_rsv_size <= SZ_128M)
881 		return false;
882 
883 	/*
884 	 * We have tickets queued, bail so we don't compete with the async
885 	 * flushers.
886 	 */
887 	if (space_info->reclaim_size)
888 		return false;
889 
890 	/*
891 	 * If we have over half of the free space occupied by reservations or
892 	 * pinned then we want to start flushing.
893 	 *
894 	 * We do not do the traditional thing here, which is to say
895 	 *
896 	 *   if (used >= ((total_bytes + avail) / 2))
897 	 *     return 1;
898 	 *
899 	 * because this doesn't quite work how we want.  If we had more than 50%
900 	 * of the space_info used by bytes_used and we had 0 available we'd just
901 	 * constantly run the background flusher.  Instead we want it to kick in
902 	 * if our reclaimable space exceeds our clamped free space.
903 	 *
904 	 * Our clamping range is 2^1 -> 2^8.  Practically speaking that means
905 	 * the following:
906 	 *
907 	 * Amount of RAM        Minimum threshold       Maximum threshold
908 	 *
909 	 *        256GiB                     1GiB                  128GiB
910 	 *        128GiB                   512MiB                   64GiB
911 	 *         64GiB                   256MiB                   32GiB
912 	 *         32GiB                   128MiB                   16GiB
913 	 *         16GiB                    64MiB                    8GiB
914 	 *
915 	 * These are the range our thresholds will fall in, corresponding to how
916 	 * much delalloc we need for the background flusher to kick in.
917 	 */
918 
919 	thresh = calc_available_free_space(fs_info, space_info,
920 					   BTRFS_RESERVE_FLUSH_ALL);
921 	used = space_info->bytes_used + space_info->bytes_reserved +
922 	       space_info->bytes_readonly + global_rsv_size;
923 	if (used < total)
924 		thresh += total - used;
925 	thresh >>= space_info->clamp;
926 
927 	used = space_info->bytes_pinned;
928 
929 	/*
930 	 * If we have more ordered bytes than delalloc bytes then we're either
931 	 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
932 	 * around.  Preemptive flushing is only useful in that it can free up
933 	 * space before tickets need to wait for things to finish.  In the case
934 	 * of ordered extents, preemptively waiting on ordered extents gets us
935 	 * nothing, if our reservations are tied up in ordered extents we'll
936 	 * simply have to slow down writers by forcing them to wait on ordered
937 	 * extents.
938 	 *
939 	 * In the case that ordered is larger than delalloc, only include the
940 	 * block reserves that we would actually be able to directly reclaim
941 	 * from.  In this case if we're heavy on metadata operations this will
942 	 * clearly be heavy enough to warrant preemptive flushing.  In the case
943 	 * of heavy DIO or ordered reservations, preemptive flushing will just
944 	 * waste time and cause us to slow down.
945 	 *
946 	 * We want to make sure we truly are maxed out on ordered however, so
947 	 * cut ordered in half, and if it's still higher than delalloc then we
948 	 * can keep flushing.  This is to avoid the case where we start
949 	 * flushing, and now delalloc == ordered and we stop preemptively
950 	 * flushing when we could still have several gigs of delalloc to flush.
951 	 */
952 	ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
953 	delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
954 	if (ordered >= delalloc)
955 		used += fs_info->delayed_refs_rsv.reserved +
956 			fs_info->delayed_block_rsv.reserved;
957 	else
958 		used += space_info->bytes_may_use - global_rsv_size;
959 
960 	return (used >= thresh && !btrfs_fs_closing(fs_info) &&
961 		!test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
962 }
963 
steal_from_global_rsv(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,struct reserve_ticket * ticket)964 static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
965 				  struct btrfs_space_info *space_info,
966 				  struct reserve_ticket *ticket)
967 {
968 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
969 	u64 min_bytes;
970 
971 	if (!ticket->steal)
972 		return false;
973 
974 	if (global_rsv->space_info != space_info)
975 		return false;
976 
977 	spin_lock(&global_rsv->lock);
978 	min_bytes = div_factor(global_rsv->size, 1);
979 	if (global_rsv->reserved < min_bytes + ticket->bytes) {
980 		spin_unlock(&global_rsv->lock);
981 		return false;
982 	}
983 	global_rsv->reserved -= ticket->bytes;
984 	remove_ticket(space_info, ticket);
985 	ticket->bytes = 0;
986 	wake_up(&ticket->wait);
987 	space_info->tickets_id++;
988 	if (global_rsv->reserved < global_rsv->size)
989 		global_rsv->full = 0;
990 	spin_unlock(&global_rsv->lock);
991 
992 	return true;
993 }
994 
995 /*
996  * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets
997  * @fs_info - fs_info for this fs
998  * @space_info - the space info we were flushing
999  *
1000  * We call this when we've exhausted our flushing ability and haven't made
1001  * progress in satisfying tickets.  The reservation code handles tickets in
1002  * order, so if there is a large ticket first and then smaller ones we could
1003  * very well satisfy the smaller tickets.  This will attempt to wake up any
1004  * tickets in the list to catch this case.
1005  *
1006  * This function returns true if it was able to make progress by clearing out
1007  * other tickets, or if it stumbles across a ticket that was smaller than the
1008  * first ticket.
1009  */
maybe_fail_all_tickets(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)1010 static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
1011 				   struct btrfs_space_info *space_info)
1012 {
1013 	struct reserve_ticket *ticket;
1014 	u64 tickets_id = space_info->tickets_id;
1015 	const bool aborted = BTRFS_FS_ERROR(fs_info);
1016 
1017 	trace_btrfs_fail_all_tickets(fs_info, space_info);
1018 
1019 	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
1020 		btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
1021 		__btrfs_dump_space_info(fs_info, space_info);
1022 	}
1023 
1024 	while (!list_empty(&space_info->tickets) &&
1025 	       tickets_id == space_info->tickets_id) {
1026 		ticket = list_first_entry(&space_info->tickets,
1027 					  struct reserve_ticket, list);
1028 
1029 		if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket))
1030 			return true;
1031 
1032 		if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1033 			btrfs_info(fs_info, "failing ticket with %llu bytes",
1034 				   ticket->bytes);
1035 
1036 		remove_ticket(space_info, ticket);
1037 		if (aborted)
1038 			ticket->error = -EIO;
1039 		else
1040 			ticket->error = -ENOSPC;
1041 		wake_up(&ticket->wait);
1042 
1043 		/*
1044 		 * We're just throwing tickets away, so more flushing may not
1045 		 * trip over btrfs_try_granting_tickets, so we need to call it
1046 		 * here to see if we can make progress with the next ticket in
1047 		 * the list.
1048 		 */
1049 		if (!aborted)
1050 			btrfs_try_granting_tickets(fs_info, space_info);
1051 	}
1052 	return (tickets_id != space_info->tickets_id);
1053 }
1054 
1055 /*
1056  * This is for normal flushers, we can wait all goddamned day if we want to.  We
1057  * will loop and continuously try to flush as long as we are making progress.
1058  * We count progress as clearing off tickets each time we have to loop.
1059  */
btrfs_async_reclaim_metadata_space(struct work_struct * work)1060 static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
1061 {
1062 	struct btrfs_fs_info *fs_info;
1063 	struct btrfs_space_info *space_info;
1064 	u64 to_reclaim;
1065 	enum btrfs_flush_state flush_state;
1066 	int commit_cycles = 0;
1067 	u64 last_tickets_id;
1068 
1069 	fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
1070 	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1071 
1072 	spin_lock(&space_info->lock);
1073 	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1074 	if (!to_reclaim) {
1075 		space_info->flush = 0;
1076 		spin_unlock(&space_info->lock);
1077 		return;
1078 	}
1079 	last_tickets_id = space_info->tickets_id;
1080 	spin_unlock(&space_info->lock);
1081 
1082 	flush_state = FLUSH_DELAYED_ITEMS_NR;
1083 	do {
1084 		flush_space(fs_info, space_info, to_reclaim, flush_state, false);
1085 		spin_lock(&space_info->lock);
1086 		if (list_empty(&space_info->tickets)) {
1087 			space_info->flush = 0;
1088 			spin_unlock(&space_info->lock);
1089 			return;
1090 		}
1091 		to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1092 							      space_info);
1093 		if (last_tickets_id == space_info->tickets_id) {
1094 			flush_state++;
1095 		} else {
1096 			last_tickets_id = space_info->tickets_id;
1097 			flush_state = FLUSH_DELAYED_ITEMS_NR;
1098 			if (commit_cycles)
1099 				commit_cycles--;
1100 		}
1101 
1102 		/*
1103 		 * We do not want to empty the system of delalloc unless we're
1104 		 * under heavy pressure, so allow one trip through the flushing
1105 		 * logic before we start doing a FLUSH_DELALLOC_FULL.
1106 		 */
1107 		if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
1108 			flush_state++;
1109 
1110 		/*
1111 		 * We don't want to force a chunk allocation until we've tried
1112 		 * pretty hard to reclaim space.  Think of the case where we
1113 		 * freed up a bunch of space and so have a lot of pinned space
1114 		 * to reclaim.  We would rather use that than possibly create a
1115 		 * underutilized metadata chunk.  So if this is our first run
1116 		 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1117 		 * commit the transaction.  If nothing has changed the next go
1118 		 * around then we can force a chunk allocation.
1119 		 */
1120 		if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1121 			flush_state++;
1122 
1123 		if (flush_state > COMMIT_TRANS) {
1124 			commit_cycles++;
1125 			if (commit_cycles > 2) {
1126 				if (maybe_fail_all_tickets(fs_info, space_info)) {
1127 					flush_state = FLUSH_DELAYED_ITEMS_NR;
1128 					commit_cycles--;
1129 				} else {
1130 					space_info->flush = 0;
1131 				}
1132 			} else {
1133 				flush_state = FLUSH_DELAYED_ITEMS_NR;
1134 			}
1135 		}
1136 		spin_unlock(&space_info->lock);
1137 	} while (flush_state <= COMMIT_TRANS);
1138 }
1139 
1140 /*
1141  * This handles pre-flushing of metadata space before we get to the point that
1142  * we need to start blocking threads on tickets.  The logic here is different
1143  * from the other flush paths because it doesn't rely on tickets to tell us how
1144  * much we need to flush, instead it attempts to keep us below the 80% full
1145  * watermark of space by flushing whichever reservation pool is currently the
1146  * largest.
1147  */
btrfs_preempt_reclaim_metadata_space(struct work_struct * work)1148 static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
1149 {
1150 	struct btrfs_fs_info *fs_info;
1151 	struct btrfs_space_info *space_info;
1152 	struct btrfs_block_rsv *delayed_block_rsv;
1153 	struct btrfs_block_rsv *delayed_refs_rsv;
1154 	struct btrfs_block_rsv *global_rsv;
1155 	struct btrfs_block_rsv *trans_rsv;
1156 	int loops = 0;
1157 
1158 	fs_info = container_of(work, struct btrfs_fs_info,
1159 			       preempt_reclaim_work);
1160 	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1161 	delayed_block_rsv = &fs_info->delayed_block_rsv;
1162 	delayed_refs_rsv = &fs_info->delayed_refs_rsv;
1163 	global_rsv = &fs_info->global_block_rsv;
1164 	trans_rsv = &fs_info->trans_block_rsv;
1165 
1166 	spin_lock(&space_info->lock);
1167 	while (need_preemptive_reclaim(fs_info, space_info)) {
1168 		enum btrfs_flush_state flush;
1169 		u64 delalloc_size = 0;
1170 		u64 to_reclaim, block_rsv_size;
1171 		u64 global_rsv_size = global_rsv->reserved;
1172 
1173 		loops++;
1174 
1175 		/*
1176 		 * We don't have a precise counter for the metadata being
1177 		 * reserved for delalloc, so we'll approximate it by subtracting
1178 		 * out the block rsv's space from the bytes_may_use.  If that
1179 		 * amount is higher than the individual reserves, then we can
1180 		 * assume it's tied up in delalloc reservations.
1181 		 */
1182 		block_rsv_size = global_rsv_size +
1183 			delayed_block_rsv->reserved +
1184 			delayed_refs_rsv->reserved +
1185 			trans_rsv->reserved;
1186 		if (block_rsv_size < space_info->bytes_may_use)
1187 			delalloc_size = space_info->bytes_may_use - block_rsv_size;
1188 
1189 		/*
1190 		 * We don't want to include the global_rsv in our calculation,
1191 		 * because that's space we can't touch.  Subtract it from the
1192 		 * block_rsv_size for the next checks.
1193 		 */
1194 		block_rsv_size -= global_rsv_size;
1195 
1196 		/*
1197 		 * We really want to avoid flushing delalloc too much, as it
1198 		 * could result in poor allocation patterns, so only flush it if
1199 		 * it's larger than the rest of the pools combined.
1200 		 */
1201 		if (delalloc_size > block_rsv_size) {
1202 			to_reclaim = delalloc_size;
1203 			flush = FLUSH_DELALLOC;
1204 		} else if (space_info->bytes_pinned >
1205 			   (delayed_block_rsv->reserved +
1206 			    delayed_refs_rsv->reserved)) {
1207 			to_reclaim = space_info->bytes_pinned;
1208 			flush = COMMIT_TRANS;
1209 		} else if (delayed_block_rsv->reserved >
1210 			   delayed_refs_rsv->reserved) {
1211 			to_reclaim = delayed_block_rsv->reserved;
1212 			flush = FLUSH_DELAYED_ITEMS_NR;
1213 		} else {
1214 			to_reclaim = delayed_refs_rsv->reserved;
1215 			flush = FLUSH_DELAYED_REFS_NR;
1216 		}
1217 
1218 		spin_unlock(&space_info->lock);
1219 
1220 		/*
1221 		 * We don't want to reclaim everything, just a portion, so scale
1222 		 * down the to_reclaim by 1/4.  If it takes us down to 0,
1223 		 * reclaim 1 items worth.
1224 		 */
1225 		to_reclaim >>= 2;
1226 		if (!to_reclaim)
1227 			to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1228 		flush_space(fs_info, space_info, to_reclaim, flush, true);
1229 		cond_resched();
1230 		spin_lock(&space_info->lock);
1231 	}
1232 
1233 	/* We only went through once, back off our clamping. */
1234 	if (loops == 1 && !space_info->reclaim_size)
1235 		space_info->clamp = max(1, space_info->clamp - 1);
1236 	trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1237 	spin_unlock(&space_info->lock);
1238 }
1239 
1240 /*
1241  * FLUSH_DELALLOC_WAIT:
1242  *   Space is freed from flushing delalloc in one of two ways.
1243  *
1244  *   1) compression is on and we allocate less space than we reserved
1245  *   2) we are overwriting existing space
1246  *
1247  *   For #1 that extra space is reclaimed as soon as the delalloc pages are
1248  *   COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1249  *   length to ->bytes_reserved, and subtracts the reserved space from
1250  *   ->bytes_may_use.
1251  *
1252  *   For #2 this is trickier.  Once the ordered extent runs we will drop the
1253  *   extent in the range we are overwriting, which creates a delayed ref for
1254  *   that freed extent.  This however is not reclaimed until the transaction
1255  *   commits, thus the next stages.
1256  *
1257  * RUN_DELAYED_IPUTS
1258  *   If we are freeing inodes, we want to make sure all delayed iputs have
1259  *   completed, because they could have been on an inode with i_nlink == 0, and
1260  *   thus have been truncated and freed up space.  But again this space is not
1261  *   immediately re-usable, it comes in the form of a delayed ref, which must be
1262  *   run and then the transaction must be committed.
1263  *
1264  * COMMIT_TRANS
1265  *   This is where we reclaim all of the pinned space generated by running the
1266  *   iputs
1267  *
1268  * ALLOC_CHUNK_FORCE
1269  *   For data we start with alloc chunk force, however we could have been full
1270  *   before, and then the transaction commit could have freed new block groups,
1271  *   so if we now have space to allocate do the force chunk allocation.
1272  */
1273 static const enum btrfs_flush_state data_flush_states[] = {
1274 	FLUSH_DELALLOC_FULL,
1275 	RUN_DELAYED_IPUTS,
1276 	COMMIT_TRANS,
1277 	ALLOC_CHUNK_FORCE,
1278 };
1279 
btrfs_async_reclaim_data_space(struct work_struct * work)1280 static void btrfs_async_reclaim_data_space(struct work_struct *work)
1281 {
1282 	struct btrfs_fs_info *fs_info;
1283 	struct btrfs_space_info *space_info;
1284 	u64 last_tickets_id;
1285 	enum btrfs_flush_state flush_state = 0;
1286 
1287 	fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1288 	space_info = fs_info->data_sinfo;
1289 
1290 	spin_lock(&space_info->lock);
1291 	if (list_empty(&space_info->tickets)) {
1292 		space_info->flush = 0;
1293 		spin_unlock(&space_info->lock);
1294 		return;
1295 	}
1296 	last_tickets_id = space_info->tickets_id;
1297 	spin_unlock(&space_info->lock);
1298 
1299 	while (!space_info->full) {
1300 		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1301 		spin_lock(&space_info->lock);
1302 		if (list_empty(&space_info->tickets)) {
1303 			space_info->flush = 0;
1304 			spin_unlock(&space_info->lock);
1305 			return;
1306 		}
1307 
1308 		/* Something happened, fail everything and bail. */
1309 		if (BTRFS_FS_ERROR(fs_info))
1310 			goto aborted_fs;
1311 		last_tickets_id = space_info->tickets_id;
1312 		spin_unlock(&space_info->lock);
1313 	}
1314 
1315 	while (flush_state < ARRAY_SIZE(data_flush_states)) {
1316 		flush_space(fs_info, space_info, U64_MAX,
1317 			    data_flush_states[flush_state], false);
1318 		spin_lock(&space_info->lock);
1319 		if (list_empty(&space_info->tickets)) {
1320 			space_info->flush = 0;
1321 			spin_unlock(&space_info->lock);
1322 			return;
1323 		}
1324 
1325 		if (last_tickets_id == space_info->tickets_id) {
1326 			flush_state++;
1327 		} else {
1328 			last_tickets_id = space_info->tickets_id;
1329 			flush_state = 0;
1330 		}
1331 
1332 		if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1333 			if (space_info->full) {
1334 				if (maybe_fail_all_tickets(fs_info, space_info))
1335 					flush_state = 0;
1336 				else
1337 					space_info->flush = 0;
1338 			} else {
1339 				flush_state = 0;
1340 			}
1341 
1342 			/* Something happened, fail everything and bail. */
1343 			if (BTRFS_FS_ERROR(fs_info))
1344 				goto aborted_fs;
1345 
1346 		}
1347 		spin_unlock(&space_info->lock);
1348 	}
1349 	return;
1350 
1351 aborted_fs:
1352 	maybe_fail_all_tickets(fs_info, space_info);
1353 	space_info->flush = 0;
1354 	spin_unlock(&space_info->lock);
1355 }
1356 
btrfs_init_async_reclaim_work(struct btrfs_fs_info * fs_info)1357 void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1358 {
1359 	INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1360 	INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1361 	INIT_WORK(&fs_info->preempt_reclaim_work,
1362 		  btrfs_preempt_reclaim_metadata_space);
1363 }
1364 
1365 static const enum btrfs_flush_state priority_flush_states[] = {
1366 	FLUSH_DELAYED_ITEMS_NR,
1367 	FLUSH_DELAYED_ITEMS,
1368 	ALLOC_CHUNK,
1369 };
1370 
1371 static const enum btrfs_flush_state evict_flush_states[] = {
1372 	FLUSH_DELAYED_ITEMS_NR,
1373 	FLUSH_DELAYED_ITEMS,
1374 	FLUSH_DELAYED_REFS_NR,
1375 	FLUSH_DELAYED_REFS,
1376 	FLUSH_DELALLOC,
1377 	FLUSH_DELALLOC_WAIT,
1378 	FLUSH_DELALLOC_FULL,
1379 	ALLOC_CHUNK,
1380 	COMMIT_TRANS,
1381 };
1382 
priority_reclaim_metadata_space(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,struct reserve_ticket * ticket,const enum btrfs_flush_state * states,int states_nr)1383 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1384 				struct btrfs_space_info *space_info,
1385 				struct reserve_ticket *ticket,
1386 				const enum btrfs_flush_state *states,
1387 				int states_nr)
1388 {
1389 	u64 to_reclaim;
1390 	int flush_state = 0;
1391 
1392 	spin_lock(&space_info->lock);
1393 	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1394 	/*
1395 	 * This is the priority reclaim path, so to_reclaim could be >0 still
1396 	 * because we may have only satisfied the priority tickets and still
1397 	 * left non priority tickets on the list.  We would then have
1398 	 * to_reclaim but ->bytes == 0.
1399 	 */
1400 	if (ticket->bytes == 0) {
1401 		spin_unlock(&space_info->lock);
1402 		return;
1403 	}
1404 
1405 	while (flush_state < states_nr) {
1406 		spin_unlock(&space_info->lock);
1407 		flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1408 			    false);
1409 		flush_state++;
1410 		spin_lock(&space_info->lock);
1411 		if (ticket->bytes == 0) {
1412 			spin_unlock(&space_info->lock);
1413 			return;
1414 		}
1415 	}
1416 
1417 	/* Attempt to steal from the global rsv if we can. */
1418 	if (!steal_from_global_rsv(fs_info, space_info, ticket)) {
1419 		ticket->error = -ENOSPC;
1420 		remove_ticket(space_info, ticket);
1421 	}
1422 
1423 	/*
1424 	 * We must run try_granting_tickets here because we could be a large
1425 	 * ticket in front of a smaller ticket that can now be satisfied with
1426 	 * the available space.
1427 	 */
1428 	btrfs_try_granting_tickets(fs_info, space_info);
1429 	spin_unlock(&space_info->lock);
1430 }
1431 
priority_reclaim_data_space(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,struct reserve_ticket * ticket)1432 static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1433 					struct btrfs_space_info *space_info,
1434 					struct reserve_ticket *ticket)
1435 {
1436 	spin_lock(&space_info->lock);
1437 
1438 	/* We could have been granted before we got here. */
1439 	if (ticket->bytes == 0) {
1440 		spin_unlock(&space_info->lock);
1441 		return;
1442 	}
1443 
1444 	while (!space_info->full) {
1445 		spin_unlock(&space_info->lock);
1446 		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1447 		spin_lock(&space_info->lock);
1448 		if (ticket->bytes == 0) {
1449 			spin_unlock(&space_info->lock);
1450 			return;
1451 		}
1452 	}
1453 
1454 	ticket->error = -ENOSPC;
1455 	remove_ticket(space_info, ticket);
1456 	btrfs_try_granting_tickets(fs_info, space_info);
1457 	spin_unlock(&space_info->lock);
1458 }
1459 
wait_reserve_ticket(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,struct reserve_ticket * ticket)1460 static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1461 				struct btrfs_space_info *space_info,
1462 				struct reserve_ticket *ticket)
1463 
1464 {
1465 	DEFINE_WAIT(wait);
1466 	int ret = 0;
1467 
1468 	spin_lock(&space_info->lock);
1469 	while (ticket->bytes > 0 && ticket->error == 0) {
1470 		ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1471 		if (ret) {
1472 			/*
1473 			 * Delete us from the list. After we unlock the space
1474 			 * info, we don't want the async reclaim job to reserve
1475 			 * space for this ticket. If that would happen, then the
1476 			 * ticket's task would not known that space was reserved
1477 			 * despite getting an error, resulting in a space leak
1478 			 * (bytes_may_use counter of our space_info).
1479 			 */
1480 			remove_ticket(space_info, ticket);
1481 			ticket->error = -EINTR;
1482 			break;
1483 		}
1484 		spin_unlock(&space_info->lock);
1485 
1486 		schedule();
1487 
1488 		finish_wait(&ticket->wait, &wait);
1489 		spin_lock(&space_info->lock);
1490 	}
1491 	spin_unlock(&space_info->lock);
1492 }
1493 
1494 /**
1495  * Do the appropriate flushing and waiting for a ticket
1496  *
1497  * @fs_info:    the filesystem
1498  * @space_info: space info for the reservation
1499  * @ticket:     ticket for the reservation
1500  * @start_ns:   timestamp when the reservation started
1501  * @orig_bytes: amount of bytes originally reserved
1502  * @flush:      how much we can flush
1503  *
1504  * This does the work of figuring out how to flush for the ticket, waiting for
1505  * the reservation, and returning the appropriate error if there is one.
1506  */
handle_reserve_ticket(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,struct reserve_ticket * ticket,u64 start_ns,u64 orig_bytes,enum btrfs_reserve_flush_enum flush)1507 static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1508 				 struct btrfs_space_info *space_info,
1509 				 struct reserve_ticket *ticket,
1510 				 u64 start_ns, u64 orig_bytes,
1511 				 enum btrfs_reserve_flush_enum flush)
1512 {
1513 	int ret;
1514 
1515 	switch (flush) {
1516 	case BTRFS_RESERVE_FLUSH_DATA:
1517 	case BTRFS_RESERVE_FLUSH_ALL:
1518 	case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1519 		wait_reserve_ticket(fs_info, space_info, ticket);
1520 		break;
1521 	case BTRFS_RESERVE_FLUSH_LIMIT:
1522 		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1523 						priority_flush_states,
1524 						ARRAY_SIZE(priority_flush_states));
1525 		break;
1526 	case BTRFS_RESERVE_FLUSH_EVICT:
1527 		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1528 						evict_flush_states,
1529 						ARRAY_SIZE(evict_flush_states));
1530 		break;
1531 	case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1532 		priority_reclaim_data_space(fs_info, space_info, ticket);
1533 		break;
1534 	default:
1535 		ASSERT(0);
1536 		break;
1537 	}
1538 
1539 	ret = ticket->error;
1540 	ASSERT(list_empty(&ticket->list));
1541 	/*
1542 	 * Check that we can't have an error set if the reservation succeeded,
1543 	 * as that would confuse tasks and lead them to error out without
1544 	 * releasing reserved space (if an error happens the expectation is that
1545 	 * space wasn't reserved at all).
1546 	 */
1547 	ASSERT(!(ticket->bytes == 0 && ticket->error));
1548 	trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1549 				   start_ns, flush, ticket->error);
1550 	return ret;
1551 }
1552 
1553 /*
1554  * This returns true if this flush state will go through the ordinary flushing
1555  * code.
1556  */
is_normal_flushing(enum btrfs_reserve_flush_enum flush)1557 static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1558 {
1559 	return	(flush == BTRFS_RESERVE_FLUSH_ALL) ||
1560 		(flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1561 }
1562 
maybe_clamp_preempt(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info)1563 static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1564 				       struct btrfs_space_info *space_info)
1565 {
1566 	u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1567 	u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1568 
1569 	/*
1570 	 * If we're heavy on ordered operations then clamping won't help us.  We
1571 	 * need to clamp specifically to keep up with dirty'ing buffered
1572 	 * writers, because there's not a 1:1 correlation of writing delalloc
1573 	 * and freeing space, like there is with flushing delayed refs or
1574 	 * delayed nodes.  If we're already more ordered than delalloc then
1575 	 * we're keeping up, otherwise we aren't and should probably clamp.
1576 	 */
1577 	if (ordered < delalloc)
1578 		space_info->clamp = min(space_info->clamp + 1, 8);
1579 }
1580 
can_steal(enum btrfs_reserve_flush_enum flush)1581 static inline bool can_steal(enum btrfs_reserve_flush_enum flush)
1582 {
1583 	return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1584 		flush == BTRFS_RESERVE_FLUSH_EVICT);
1585 }
1586 
1587 /**
1588  * Try to reserve bytes from the block_rsv's space
1589  *
1590  * @fs_info:    the filesystem
1591  * @space_info: space info we want to allocate from
1592  * @orig_bytes: number of bytes we want
1593  * @flush:      whether or not we can flush to make our reservation
1594  *
1595  * This will reserve orig_bytes number of bytes from the space info associated
1596  * with the block_rsv.  If there is not enough space it will make an attempt to
1597  * flush out space to make room.  It will do this by flushing delalloc if
1598  * possible or committing the transaction.  If flush is 0 then no attempts to
1599  * regain reservations will be made and this will fail if there is not enough
1600  * space already.
1601  */
__reserve_bytes(struct btrfs_fs_info * fs_info,struct btrfs_space_info * space_info,u64 orig_bytes,enum btrfs_reserve_flush_enum flush)1602 static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1603 			   struct btrfs_space_info *space_info, u64 orig_bytes,
1604 			   enum btrfs_reserve_flush_enum flush)
1605 {
1606 	struct work_struct *async_work;
1607 	struct reserve_ticket ticket;
1608 	u64 start_ns = 0;
1609 	u64 used;
1610 	int ret = 0;
1611 	bool pending_tickets;
1612 
1613 	ASSERT(orig_bytes);
1614 	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
1615 
1616 	if (flush == BTRFS_RESERVE_FLUSH_DATA)
1617 		async_work = &fs_info->async_data_reclaim_work;
1618 	else
1619 		async_work = &fs_info->async_reclaim_work;
1620 
1621 	spin_lock(&space_info->lock);
1622 	ret = -ENOSPC;
1623 	used = btrfs_space_info_used(space_info, true);
1624 
1625 	/*
1626 	 * We don't want NO_FLUSH allocations to jump everybody, they can
1627 	 * generally handle ENOSPC in a different way, so treat them the same as
1628 	 * normal flushers when it comes to skipping pending tickets.
1629 	 */
1630 	if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1631 		pending_tickets = !list_empty(&space_info->tickets) ||
1632 			!list_empty(&space_info->priority_tickets);
1633 	else
1634 		pending_tickets = !list_empty(&space_info->priority_tickets);
1635 
1636 	/*
1637 	 * Carry on if we have enough space (short-circuit) OR call
1638 	 * can_overcommit() to ensure we can overcommit to continue.
1639 	 */
1640 	if (!pending_tickets &&
1641 	    ((used + orig_bytes <= writable_total_bytes(fs_info, space_info)) ||
1642 	     btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1643 		btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1644 						      orig_bytes);
1645 		ret = 0;
1646 	}
1647 
1648 	/*
1649 	 * If we couldn't make a reservation then setup our reservation ticket
1650 	 * and kick the async worker if it's not already running.
1651 	 *
1652 	 * If we are a priority flusher then we just need to add our ticket to
1653 	 * the list and we will do our own flushing further down.
1654 	 */
1655 	if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
1656 		ticket.bytes = orig_bytes;
1657 		ticket.error = 0;
1658 		space_info->reclaim_size += ticket.bytes;
1659 		init_waitqueue_head(&ticket.wait);
1660 		ticket.steal = can_steal(flush);
1661 		if (trace_btrfs_reserve_ticket_enabled())
1662 			start_ns = ktime_get_ns();
1663 
1664 		if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1665 		    flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1666 		    flush == BTRFS_RESERVE_FLUSH_DATA) {
1667 			list_add_tail(&ticket.list, &space_info->tickets);
1668 			if (!space_info->flush) {
1669 				/*
1670 				 * We were forced to add a reserve ticket, so
1671 				 * our preemptive flushing is unable to keep
1672 				 * up.  Clamp down on the threshold for the
1673 				 * preemptive flushing in order to keep up with
1674 				 * the workload.
1675 				 */
1676 				maybe_clamp_preempt(fs_info, space_info);
1677 
1678 				space_info->flush = 1;
1679 				trace_btrfs_trigger_flush(fs_info,
1680 							  space_info->flags,
1681 							  orig_bytes, flush,
1682 							  "enospc");
1683 				queue_work(system_unbound_wq, async_work);
1684 			}
1685 		} else {
1686 			list_add_tail(&ticket.list,
1687 				      &space_info->priority_tickets);
1688 		}
1689 	} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1690 		/*
1691 		 * We will do the space reservation dance during log replay,
1692 		 * which means we won't have fs_info->fs_root set, so don't do
1693 		 * the async reclaim as we will panic.
1694 		 */
1695 		if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1696 		    !work_busy(&fs_info->preempt_reclaim_work) &&
1697 		    need_preemptive_reclaim(fs_info, space_info)) {
1698 			trace_btrfs_trigger_flush(fs_info, space_info->flags,
1699 						  orig_bytes, flush, "preempt");
1700 			queue_work(system_unbound_wq,
1701 				   &fs_info->preempt_reclaim_work);
1702 		}
1703 	}
1704 	spin_unlock(&space_info->lock);
1705 	if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
1706 		return ret;
1707 
1708 	return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1709 				     orig_bytes, flush);
1710 }
1711 
1712 /**
1713  * Trye to reserve metadata bytes from the block_rsv's space
1714  *
1715  * @fs_info:    the filesystem
1716  * @block_rsv:  block_rsv we're allocating for
1717  * @orig_bytes: number of bytes we want
1718  * @flush:      whether or not we can flush to make our reservation
1719  *
1720  * This will reserve orig_bytes number of bytes from the space info associated
1721  * with the block_rsv.  If there is not enough space it will make an attempt to
1722  * flush out space to make room.  It will do this by flushing delalloc if
1723  * possible or committing the transaction.  If flush is 0 then no attempts to
1724  * regain reservations will be made and this will fail if there is not enough
1725  * space already.
1726  */
btrfs_reserve_metadata_bytes(struct btrfs_fs_info * fs_info,struct btrfs_block_rsv * block_rsv,u64 orig_bytes,enum btrfs_reserve_flush_enum flush)1727 int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1728 				 struct btrfs_block_rsv *block_rsv,
1729 				 u64 orig_bytes,
1730 				 enum btrfs_reserve_flush_enum flush)
1731 {
1732 	int ret;
1733 
1734 	ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush);
1735 	if (ret == -ENOSPC) {
1736 		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1737 					      block_rsv->space_info->flags,
1738 					      orig_bytes, 1);
1739 
1740 		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1741 			btrfs_dump_space_info(fs_info, block_rsv->space_info,
1742 					      orig_bytes, 0);
1743 	}
1744 	return ret;
1745 }
1746 
1747 /**
1748  * Try to reserve data bytes for an allocation
1749  *
1750  * @fs_info: the filesystem
1751  * @bytes:   number of bytes we need
1752  * @flush:   how we are allowed to flush
1753  *
1754  * This will reserve bytes from the data space info.  If there is not enough
1755  * space then we will attempt to flush space as specified by flush.
1756  */
btrfs_reserve_data_bytes(struct btrfs_fs_info * fs_info,u64 bytes,enum btrfs_reserve_flush_enum flush)1757 int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1758 			     enum btrfs_reserve_flush_enum flush)
1759 {
1760 	struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1761 	int ret;
1762 
1763 	ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1764 	       flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE ||
1765 	       flush == BTRFS_RESERVE_NO_FLUSH);
1766 	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1767 
1768 	ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1769 	if (ret == -ENOSPC) {
1770 		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1771 					      data_sinfo->flags, bytes, 1);
1772 		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1773 			btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
1774 	}
1775 	return ret;
1776 }
1777 
1778 /* Dump all the space infos when we abort a transaction due to ENOSPC. */
btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info * fs_info)1779 __cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
1780 {
1781 	struct btrfs_space_info *space_info;
1782 
1783 	btrfs_info(fs_info, "dumping space info:");
1784 	list_for_each_entry(space_info, &fs_info->space_info, list) {
1785 		spin_lock(&space_info->lock);
1786 		__btrfs_dump_space_info(fs_info, space_info);
1787 		spin_unlock(&space_info->lock);
1788 	}
1789 	dump_global_block_rsv(fs_info);
1790 }
1791