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#include "fs.h"
  14#include "accessors.h"
  15#include "extent-tree.h"
  16
  17/*
  18 * HOW DOES SPACE RESERVATION WORK
  19 *
  20 * If you want to know about delalloc specifically, there is a separate comment
  21 * for that with the delalloc code.  This comment is about how the whole system
  22 * works generally.
  23 *
  24 * BASIC CONCEPTS
  25 *
  26 *   1) space_info.  This is the ultimate arbiter of how much space we can use.
  27 *   There's a description of the bytes_ fields with the struct declaration,
  28 *   refer to that for specifics on each field.  Suffice it to say that for
  29 *   reservations we care about total_bytes - SUM(space_info->bytes_) when
  30 *   determining if there is space to make an allocation.  There is a space_info
  31 *   for METADATA, SYSTEM, and DATA areas.
  32 *
  33 *   2) block_rsv's.  These are basically buckets for every different type of
  34 *   metadata reservation we have.  You can see the comment in the block_rsv
  35 *   code on the rules for each type, but generally block_rsv->reserved is how
  36 *   much space is accounted for in space_info->bytes_may_use.
  37 *
  38 *   3) btrfs_calc*_size.  These are the worst case calculations we used based
  39 *   on the number of items we will want to modify.  We have one for changing
  40 *   items, and one for inserting new items.  Generally we use these helpers to
  41 *   determine the size of the block reserves, and then use the actual bytes
  42 *   values to adjust the space_info counters.
  43 *
  44 * MAKING RESERVATIONS, THE NORMAL CASE
  45 *
  46 *   We call into either btrfs_reserve_data_bytes() or
  47 *   btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
  48 *   num_bytes we want to reserve.
  49 *
  50 *   ->reserve
  51 *     space_info->bytes_may_reserve += num_bytes
  52 *
  53 *   ->extent allocation
  54 *     Call btrfs_add_reserved_bytes() which does
  55 *     space_info->bytes_may_reserve -= num_bytes
  56 *     space_info->bytes_reserved += extent_bytes
  57 *
  58 *   ->insert reference
  59 *     Call btrfs_update_block_group() which does
  60 *     space_info->bytes_reserved -= extent_bytes
  61 *     space_info->bytes_used += extent_bytes
  62 *
  63 * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
  64 *
  65 *   Assume we are unable to simply make the reservation because we do not have
  66 *   enough space
  67 *
  68 *   -> __reserve_bytes
  69 *     create a reserve_ticket with ->bytes set to our reservation, add it to
  70 *     the tail of space_info->tickets, kick async flush thread
  71 *
  72 *   ->handle_reserve_ticket
  73 *     wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
  74 *     on the ticket.
  75 *
  76 *   -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
  77 *     Flushes various things attempting to free up space.
  78 *
  79 *   -> btrfs_try_granting_tickets()
  80 *     This is called by anything that either subtracts space from
  81 *     space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
  82 *     space_info->total_bytes.  This loops through the ->priority_tickets and
  83 *     then the ->tickets list checking to see if the reservation can be
  84 *     completed.  If it can the space is added to space_info->bytes_may_use and
  85 *     the ticket is woken up.
  86 *
  87 *   -> ticket wakeup
  88 *     Check if ->bytes == 0, if it does we got our reservation and we can carry
  89 *     on, if not return the appropriate error (ENOSPC, but can be EINTR if we
  90 *     were interrupted.)
  91 *
  92 * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
  93 *
  94 *   Same as the above, except we add ourselves to the
  95 *   space_info->priority_tickets, and we do not use ticket->wait, we simply
  96 *   call flush_space() ourselves for the states that are safe for us to call
  97 *   without deadlocking and hope for the best.
  98 *
  99 * THE FLUSHING STATES
 100 *
 101 *   Generally speaking we will have two cases for each state, a "nice" state
 102 *   and a "ALL THE THINGS" state.  In btrfs we delay a lot of work in order to
 103 *   reduce the locking over head on the various trees, and even to keep from
 104 *   doing any work at all in the case of delayed refs.  Each of these delayed
 105 *   things however hold reservations, and so letting them run allows us to
 106 *   reclaim space so we can make new reservations.
 107 *
 108 *   FLUSH_DELAYED_ITEMS
 109 *     Every inode has a delayed item to update the inode.  Take a simple write
 110 *     for example, we would update the inode item at write time to update the
 111 *     mtime, and then again at finish_ordered_io() time in order to update the
 112 *     isize or bytes.  We keep these delayed items to coalesce these operations
 113 *     into a single operation done on demand.  These are an easy way to reclaim
 114 *     metadata space.
 115 *
 116 *   FLUSH_DELALLOC
 117 *     Look at the delalloc comment to get an idea of how much space is reserved
 118 *     for delayed allocation.  We can reclaim some of this space simply by
 119 *     running delalloc, but usually we need to wait for ordered extents to
 120 *     reclaim the bulk of this space.
 121 *
 122 *   FLUSH_DELAYED_REFS
 123 *     We have a block reserve for the outstanding delayed refs space, and every
 124 *     delayed ref operation holds a reservation.  Running these is a quick way
 125 *     to reclaim space, but we want to hold this until the end because COW can
 126 *     churn a lot and we can avoid making some extent tree modifications if we
 127 *     are able to delay for as long as possible.
 128 *
 129 *   ALLOC_CHUNK
 130 *     We will skip this the first time through space reservation, because of
 131 *     overcommit and we don't want to have a lot of useless metadata space when
 132 *     our worst case reservations will likely never come true.
 133 *
 134 *   RUN_DELAYED_IPUTS
 135 *     If we're freeing inodes we're likely freeing checksums, file extent
 136 *     items, and extent tree items.  Loads of space could be freed up by these
 137 *     operations, however they won't be usable until the transaction commits.
 138 *
 139 *   COMMIT_TRANS
 140 *     This will commit the transaction.  Historically we had a lot of logic
 141 *     surrounding whether or not we'd commit the transaction, but this waits born
 142 *     out of a pre-tickets era where we could end up committing the transaction
 143 *     thousands of times in a row without making progress.  Now thanks to our
 144 *     ticketing system we know if we're not making progress and can error
 145 *     everybody out after a few commits rather than burning the disk hoping for
 146 *     a different answer.
 147 *
 148 * OVERCOMMIT
 149 *
 150 *   Because we hold so many reservations for metadata we will allow you to
 151 *   reserve more space than is currently free in the currently allocate
 152 *   metadata space.  This only happens with metadata, data does not allow
 153 *   overcommitting.
 154 *
 155 *   You can see the current logic for when we allow overcommit in
 156 *   btrfs_can_overcommit(), but it only applies to unallocated space.  If there
 157 *   is no unallocated space to be had, all reservations are kept within the
 158 *   free space in the allocated metadata chunks.
 159 *
 160 *   Because of overcommitting, you generally want to use the
 161 *   btrfs_can_overcommit() logic for metadata allocations, as it does the right
 162 *   thing with or without extra unallocated space.
 163 */
 164
 165u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
 166			  bool may_use_included)
 167{
 168	ASSERT(s_info);
 169	return s_info->bytes_used + s_info->bytes_reserved +
 170		s_info->bytes_pinned + s_info->bytes_readonly +
 171		s_info->bytes_zone_unusable +
 172		(may_use_included ? s_info->bytes_may_use : 0);
 173}
 174
 175/*
 176 * after adding space to the filesystem, we need to clear the full flags
 177 * on all the space infos.
 178 */
 179void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
 180{
 181	struct list_head *head = &info->space_info;
 182	struct btrfs_space_info *found;
 183
 184	list_for_each_entry(found, head, list)
 185		found->full = 0;
 186}
 187
 188/*
 189 * Block groups with more than this value (percents) of unusable space will be
 190 * scheduled for background reclaim.
 191 */
 192#define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH			(75)
 193
 194/*
 195 * Calculate chunk size depending on volume type (regular or zoned).
 196 */
 197static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
 198{
 199	if (btrfs_is_zoned(fs_info))
 200		return fs_info->zone_size;
 201
 202	ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
 203
 204	if (flags & BTRFS_BLOCK_GROUP_DATA)
 205		return BTRFS_MAX_DATA_CHUNK_SIZE;
 206	else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
 207		return SZ_32M;
 208
 209	/* Handle BTRFS_BLOCK_GROUP_METADATA */
 210	if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
 211		return SZ_1G;
 212
 213	return SZ_256M;
 214}
 215
 216/*
 217 * Update default chunk size.
 218 */
 219void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
 220					u64 chunk_size)
 221{
 222	WRITE_ONCE(space_info->chunk_size, chunk_size);
 223}
 224
 225static int create_space_info(struct btrfs_fs_info *info, u64 flags)
 226{
 227
 228	struct btrfs_space_info *space_info;
 229	int i;
 230	int ret;
 231
 232	space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
 233	if (!space_info)
 234		return -ENOMEM;
 235
 236	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
 237		INIT_LIST_HEAD(&space_info->block_groups[i]);
 238	init_rwsem(&space_info->groups_sem);
 239	spin_lock_init(&space_info->lock);
 240	space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
 241	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
 242	INIT_LIST_HEAD(&space_info->ro_bgs);
 243	INIT_LIST_HEAD(&space_info->tickets);
 244	INIT_LIST_HEAD(&space_info->priority_tickets);
 245	space_info->clamp = 1;
 246	btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags));
 247
 248	if (btrfs_is_zoned(info))
 249		space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH;
 250
 251	ret = btrfs_sysfs_add_space_info_type(info, space_info);
 252	if (ret)
 253		return ret;
 254
 255	list_add(&space_info->list, &info->space_info);
 256	if (flags & BTRFS_BLOCK_GROUP_DATA)
 257		info->data_sinfo = space_info;
 258
 259	return ret;
 260}
 261
 262int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
 263{
 264	struct btrfs_super_block *disk_super;
 265	u64 features;
 266	u64 flags;
 267	int mixed = 0;
 268	int ret;
 269
 270	disk_super = fs_info->super_copy;
 271	if (!btrfs_super_root(disk_super))
 272		return -EINVAL;
 273
 274	features = btrfs_super_incompat_flags(disk_super);
 275	if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
 276		mixed = 1;
 277
 278	flags = BTRFS_BLOCK_GROUP_SYSTEM;
 279	ret = create_space_info(fs_info, flags);
 280	if (ret)
 281		goto out;
 282
 283	if (mixed) {
 284		flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
 285		ret = create_space_info(fs_info, flags);
 286	} else {
 287		flags = BTRFS_BLOCK_GROUP_METADATA;
 288		ret = create_space_info(fs_info, flags);
 289		if (ret)
 290			goto out;
 291
 292		flags = BTRFS_BLOCK_GROUP_DATA;
 293		ret = create_space_info(fs_info, flags);
 294	}
 295out:
 296	return ret;
 297}
 298
 299void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
 300				struct btrfs_block_group *block_group)
 301{
 302	struct btrfs_space_info *found;
 303	int factor, index;
 304
 305	factor = btrfs_bg_type_to_factor(block_group->flags);
 306
 307	found = btrfs_find_space_info(info, block_group->flags);
 308	ASSERT(found);
 309	spin_lock(&found->lock);
 310	found->total_bytes += block_group->length;
 311	found->disk_total += block_group->length * factor;
 312	found->bytes_used += block_group->used;
 313	found->disk_used += block_group->used * factor;
 314	found->bytes_readonly += block_group->bytes_super;
 315	found->bytes_zone_unusable += block_group->zone_unusable;
 316	if (block_group->length > 0)
 317		found->full = 0;
 318	btrfs_try_granting_tickets(info, found);
 319	spin_unlock(&found->lock);
 320
 321	block_group->space_info = found;
 322
 323	index = btrfs_bg_flags_to_raid_index(block_group->flags);
 324	down_write(&found->groups_sem);
 325	list_add_tail(&block_group->list, &found->block_groups[index]);
 326	up_write(&found->groups_sem);
 327}
 328
 329struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 330					       u64 flags)
 331{
 332	struct list_head *head = &info->space_info;
 333	struct btrfs_space_info *found;
 334
 335	flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
 336
 337	list_for_each_entry(found, head, list) {
 338		if (found->flags & flags)
 339			return found;
 340	}
 341	return NULL;
 342}
 343
 344static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
 345			  struct btrfs_space_info *space_info,
 346			  enum btrfs_reserve_flush_enum flush)
 347{
 348	struct btrfs_space_info *data_sinfo;
 349	u64 profile;
 350	u64 avail;
 351	u64 data_chunk_size;
 352	int factor;
 353
 354	if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
 355		profile = btrfs_system_alloc_profile(fs_info);
 356	else
 357		profile = btrfs_metadata_alloc_profile(fs_info);
 358
 359	avail = atomic64_read(&fs_info->free_chunk_space);
 360
 361	/*
 362	 * If we have dup, raid1 or raid10 then only half of the free
 363	 * space is actually usable.  For raid56, the space info used
 364	 * doesn't include the parity drive, so we don't have to
 365	 * change the math
 366	 */
 367	factor = btrfs_bg_type_to_factor(profile);
 368	avail = div_u64(avail, factor);
 369	if (avail == 0)
 370		return 0;
 371
 372	/*
 373	 * Calculate the data_chunk_size, space_info->chunk_size is the
 374	 * "optimal" chunk size based on the fs size.  However when we actually
 375	 * allocate the chunk we will strip this down further, making it no more
 376	 * than 10% of the disk or 1G, whichever is smaller.
 377	 */
 378	data_sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA);
 379	data_chunk_size = min(data_sinfo->chunk_size,
 380			      mult_perc(fs_info->fs_devices->total_rw_bytes, 10));
 381	data_chunk_size = min_t(u64, data_chunk_size, SZ_1G);
 382
 383	/*
 384	 * Since data allocations immediately use block groups as part of the
 385	 * reservation, because we assume that data reservations will == actual
 386	 * usage, we could potentially overcommit and then immediately have that
 387	 * available space used by a data allocation, which could put us in a
 388	 * bind when we get close to filling the file system.
 389	 *
 390	 * To handle this simply remove the data_chunk_size from the available
 391	 * space.  If we are relatively empty this won't affect our ability to
 392	 * overcommit much, and if we're very close to full it'll keep us from
 393	 * getting into a position where we've given ourselves very little
 394	 * metadata wiggle room.
 395	 */
 396	if (avail <= data_chunk_size)
 397		return 0;
 398	avail -= data_chunk_size;
 399
 400	/*
 401	 * If we aren't flushing all things, let us overcommit up to
 402	 * 1/2th of the space. If we can flush, don't let us overcommit
 403	 * too much, let it overcommit up to 1/8 of the space.
 404	 */
 405	if (flush == BTRFS_RESERVE_FLUSH_ALL)
 406		avail >>= 3;
 407	else
 408		avail >>= 1;
 409	return avail;
 410}
 411
 412int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 413			 struct btrfs_space_info *space_info, u64 bytes,
 414			 enum btrfs_reserve_flush_enum flush)
 415{
 416	u64 avail;
 417	u64 used;
 418
 419	/* Don't overcommit when in mixed mode */
 420	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
 421		return 0;
 422
 423	used = btrfs_space_info_used(space_info, true);
 424	avail = calc_available_free_space(fs_info, space_info, flush);
 425
 426	if (used + bytes < space_info->total_bytes + avail)
 427		return 1;
 428	return 0;
 429}
 430
 431static void remove_ticket(struct btrfs_space_info *space_info,
 432			  struct reserve_ticket *ticket)
 433{
 434	if (!list_empty(&ticket->list)) {
 435		list_del_init(&ticket->list);
 436		ASSERT(space_info->reclaim_size >= ticket->bytes);
 437		space_info->reclaim_size -= ticket->bytes;
 438	}
 439}
 440
 441/*
 442 * This is for space we already have accounted in space_info->bytes_may_use, so
 443 * basically when we're returning space from block_rsv's.
 444 */
 445void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
 446				struct btrfs_space_info *space_info)
 447{
 448	struct list_head *head;
 449	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
 450
 451	lockdep_assert_held(&space_info->lock);
 452
 453	head = &space_info->priority_tickets;
 454again:
 455	while (!list_empty(head)) {
 456		struct reserve_ticket *ticket;
 457		u64 used = btrfs_space_info_used(space_info, true);
 458
 459		ticket = list_first_entry(head, struct reserve_ticket, list);
 460
 461		/* Check and see if our ticket can be satisfied now. */
 462		if ((used + ticket->bytes <= space_info->total_bytes) ||
 463		    btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
 464					 flush)) {
 465			btrfs_space_info_update_bytes_may_use(fs_info,
 466							      space_info,
 467							      ticket->bytes);
 468			remove_ticket(space_info, ticket);
 469			ticket->bytes = 0;
 470			space_info->tickets_id++;
 471			wake_up(&ticket->wait);
 472		} else {
 473			break;
 474		}
 475	}
 476
 477	if (head == &space_info->priority_tickets) {
 478		head = &space_info->tickets;
 479		flush = BTRFS_RESERVE_FLUSH_ALL;
 480		goto again;
 481	}
 482}
 483
 484#define DUMP_BLOCK_RSV(fs_info, rsv_name)				\
 485do {									\
 486	struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name;		\
 487	spin_lock(&__rsv->lock);					\
 488	btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu",	\
 489		   __rsv->size, __rsv->reserved);			\
 490	spin_unlock(&__rsv->lock);					\
 491} while (0)
 492
 493static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info)
 494{
 495	switch (space_info->flags) {
 496	case BTRFS_BLOCK_GROUP_SYSTEM:
 497		return "SYSTEM";
 498	case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
 499		return "DATA+METADATA";
 500	case BTRFS_BLOCK_GROUP_DATA:
 501		return "DATA";
 502	case BTRFS_BLOCK_GROUP_METADATA:
 503		return "METADATA";
 504	default:
 505		return "UNKNOWN";
 506	}
 507}
 508
 509static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
 510{
 511	DUMP_BLOCK_RSV(fs_info, global_block_rsv);
 512	DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
 513	DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
 514	DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
 515	DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
 516}
 517
 518static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 519				    struct btrfs_space_info *info)
 520{
 521	const char *flag_str = space_info_flag_to_str(info);
 522	lockdep_assert_held(&info->lock);
 523
 524	/* The free space could be negative in case of overcommit */
 525	btrfs_info(fs_info, "space_info %s has %lld free, is %sfull",
 526		   flag_str,
 527		   (s64)(info->total_bytes - btrfs_space_info_used(info, true)),
 528		   info->full ? "" : "not ");
 529	btrfs_info(fs_info,
 530"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
 531		info->total_bytes, info->bytes_used, info->bytes_pinned,
 532		info->bytes_reserved, info->bytes_may_use,
 533		info->bytes_readonly, info->bytes_zone_unusable);
 534}
 535
 536void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 537			   struct btrfs_space_info *info, u64 bytes,
 538			   int dump_block_groups)
 539{
 540	struct btrfs_block_group *cache;
 541	u64 total_avail = 0;
 542	int index = 0;
 543
 544	spin_lock(&info->lock);
 545	__btrfs_dump_space_info(fs_info, info);
 546	dump_global_block_rsv(fs_info);
 547	spin_unlock(&info->lock);
 548
 549	if (!dump_block_groups)
 550		return;
 551
 552	down_read(&info->groups_sem);
 553again:
 554	list_for_each_entry(cache, &info->block_groups[index], list) {
 555		u64 avail;
 556
 557		spin_lock(&cache->lock);
 558		avail = cache->length - cache->used - cache->pinned -
 559			cache->reserved - cache->delalloc_bytes -
 560			cache->bytes_super - cache->zone_unusable;
 561		btrfs_info(fs_info,
 562"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
 563			   cache->start, cache->length, cache->used, cache->pinned,
 564			   cache->reserved, cache->delalloc_bytes,
 565			   cache->bytes_super, cache->zone_unusable,
 566			   avail, cache->ro ? "[readonly]" : "");
 567		spin_unlock(&cache->lock);
 568		btrfs_dump_free_space(cache, bytes);
 569		total_avail += avail;
 570	}
 571	if (++index < BTRFS_NR_RAID_TYPES)
 572		goto again;
 573	up_read(&info->groups_sem);
 574
 575	btrfs_info(fs_info, "%llu bytes available across all block groups", total_avail);
 576}
 577
 578static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info,
 579					u64 to_reclaim)
 580{
 581	u64 bytes;
 582	u64 nr;
 583
 584	bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
 585	nr = div64_u64(to_reclaim, bytes);
 586	if (!nr)
 587		nr = 1;
 588	return nr;
 589}
 590
 591#define EXTENT_SIZE_PER_ITEM	SZ_256K
 592
 593/*
 594 * shrink metadata reservation for delalloc
 595 */
 596static void shrink_delalloc(struct btrfs_fs_info *fs_info,
 597			    struct btrfs_space_info *space_info,
 598			    u64 to_reclaim, bool wait_ordered,
 599			    bool for_preempt)
 600{
 601	struct btrfs_trans_handle *trans;
 602	u64 delalloc_bytes;
 603	u64 ordered_bytes;
 604	u64 items;
 605	long time_left;
 606	int loops;
 607
 608	delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
 609	ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
 610	if (delalloc_bytes == 0 && ordered_bytes == 0)
 611		return;
 612
 613	/* Calc the number of the pages we need flush for space reservation */
 614	if (to_reclaim == U64_MAX) {
 615		items = U64_MAX;
 616	} else {
 617		/*
 618		 * to_reclaim is set to however much metadata we need to
 619		 * reclaim, but reclaiming that much data doesn't really track
 620		 * exactly.  What we really want to do is reclaim full inode's
 621		 * worth of reservations, however that's not available to us
 622		 * here.  We will take a fraction of the delalloc bytes for our
 623		 * flushing loops and hope for the best.  Delalloc will expand
 624		 * the amount we write to cover an entire dirty extent, which
 625		 * will reclaim the metadata reservation for that range.  If
 626		 * it's not enough subsequent flush stages will be more
 627		 * aggressive.
 628		 */
 629		to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
 630		items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
 631	}
 632
 633	trans = current->journal_info;
 634
 635	/*
 636	 * If we are doing more ordered than delalloc we need to just wait on
 637	 * ordered extents, otherwise we'll waste time trying to flush delalloc
 638	 * that likely won't give us the space back we need.
 639	 */
 640	if (ordered_bytes > delalloc_bytes && !for_preempt)
 641		wait_ordered = true;
 642
 643	loops = 0;
 644	while ((delalloc_bytes || ordered_bytes) && loops < 3) {
 645		u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
 646		long nr_pages = min_t(u64, temp, LONG_MAX);
 647		int async_pages;
 648
 649		btrfs_start_delalloc_roots(fs_info, nr_pages, true);
 650
 651		/*
 652		 * We need to make sure any outstanding async pages are now
 653		 * processed before we continue.  This is because things like
 654		 * sync_inode() try to be smart and skip writing if the inode is
 655		 * marked clean.  We don't use filemap_fwrite for flushing
 656		 * because we want to control how many pages we write out at a
 657		 * time, thus this is the only safe way to make sure we've
 658		 * waited for outstanding compressed workers to have started
 659		 * their jobs and thus have ordered extents set up properly.
 660		 *
 661		 * This exists because we do not want to wait for each
 662		 * individual inode to finish its async work, we simply want to
 663		 * start the IO on everybody, and then come back here and wait
 664		 * for all of the async work to catch up.  Once we're done with
 665		 * that we know we'll have ordered extents for everything and we
 666		 * can decide if we wait for that or not.
 667		 *
 668		 * If we choose to replace this in the future, make absolutely
 669		 * sure that the proper waiting is being done in the async case,
 670		 * as there have been bugs in that area before.
 671		 */
 672		async_pages = atomic_read(&fs_info->async_delalloc_pages);
 673		if (!async_pages)
 674			goto skip_async;
 675
 676		/*
 677		 * We don't want to wait forever, if we wrote less pages in this
 678		 * loop than we have outstanding, only wait for that number of
 679		 * pages, otherwise we can wait for all async pages to finish
 680		 * before continuing.
 681		 */
 682		if (async_pages > nr_pages)
 683			async_pages -= nr_pages;
 684		else
 685			async_pages = 0;
 686		wait_event(fs_info->async_submit_wait,
 687			   atomic_read(&fs_info->async_delalloc_pages) <=
 688			   async_pages);
 689skip_async:
 690		loops++;
 691		if (wait_ordered && !trans) {
 692			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
 693		} else {
 694			time_left = schedule_timeout_killable(1);
 695			if (time_left)
 696				break;
 697		}
 698
 699		/*
 700		 * If we are for preemption we just want a one-shot of delalloc
 701		 * flushing so we can stop flushing if we decide we don't need
 702		 * to anymore.
 703		 */
 704		if (for_preempt)
 705			break;
 706
 707		spin_lock(&space_info->lock);
 708		if (list_empty(&space_info->tickets) &&
 709		    list_empty(&space_info->priority_tickets)) {
 710			spin_unlock(&space_info->lock);
 711			break;
 712		}
 713		spin_unlock(&space_info->lock);
 714
 715		delalloc_bytes = percpu_counter_sum_positive(
 716						&fs_info->delalloc_bytes);
 717		ordered_bytes = percpu_counter_sum_positive(
 718						&fs_info->ordered_bytes);
 719	}
 720}
 721
 722/*
 723 * Try to flush some data based on policy set by @state. This is only advisory
 724 * and may fail for various reasons. The caller is supposed to examine the
 725 * state of @space_info to detect the outcome.
 726 */
 727static void flush_space(struct btrfs_fs_info *fs_info,
 728		       struct btrfs_space_info *space_info, u64 num_bytes,
 729		       enum btrfs_flush_state state, bool for_preempt)
 730{
 731	struct btrfs_root *root = fs_info->tree_root;
 732	struct btrfs_trans_handle *trans;
 733	int nr;
 734	int ret = 0;
 735
 736	switch (state) {
 737	case FLUSH_DELAYED_ITEMS_NR:
 738	case FLUSH_DELAYED_ITEMS:
 739		if (state == FLUSH_DELAYED_ITEMS_NR)
 740			nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
 741		else
 742			nr = -1;
 743
 744		trans = btrfs_join_transaction_nostart(root);
 745		if (IS_ERR(trans)) {
 746			ret = PTR_ERR(trans);
 747			if (ret == -ENOENT)
 748				ret = 0;
 749			break;
 750		}
 751		ret = btrfs_run_delayed_items_nr(trans, nr);
 752		btrfs_end_transaction(trans);
 753		break;
 754	case FLUSH_DELALLOC:
 755	case FLUSH_DELALLOC_WAIT:
 756	case FLUSH_DELALLOC_FULL:
 757		if (state == FLUSH_DELALLOC_FULL)
 758			num_bytes = U64_MAX;
 759		shrink_delalloc(fs_info, space_info, num_bytes,
 760				state != FLUSH_DELALLOC, for_preempt);
 761		break;
 762	case FLUSH_DELAYED_REFS_NR:
 763	case FLUSH_DELAYED_REFS:
 764		trans = btrfs_join_transaction_nostart(root);
 765		if (IS_ERR(trans)) {
 766			ret = PTR_ERR(trans);
 767			if (ret == -ENOENT)
 768				ret = 0;
 769			break;
 770		}
 771		if (state == FLUSH_DELAYED_REFS_NR)
 772			btrfs_run_delayed_refs(trans, num_bytes);
 773		else
 774			btrfs_run_delayed_refs(trans, 0);
 775		btrfs_end_transaction(trans);
 776		break;
 777	case ALLOC_CHUNK:
 778	case ALLOC_CHUNK_FORCE:
 779		trans = btrfs_join_transaction(root);
 780		if (IS_ERR(trans)) {
 781			ret = PTR_ERR(trans);
 782			break;
 783		}
 784		ret = btrfs_chunk_alloc(trans,
 785				btrfs_get_alloc_profile(fs_info, space_info->flags),
 786				(state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
 787					CHUNK_ALLOC_FORCE);
 788		btrfs_end_transaction(trans);
 789
 790		if (ret > 0 || ret == -ENOSPC)
 791			ret = 0;
 792		break;
 793	case RUN_DELAYED_IPUTS:
 794		/*
 795		 * If we have pending delayed iputs then we could free up a
 796		 * bunch of pinned space, so make sure we run the iputs before
 797		 * we do our pinned bytes check below.
 798		 */
 799		btrfs_run_delayed_iputs(fs_info);
 800		btrfs_wait_on_delayed_iputs(fs_info);
 801		break;
 802	case COMMIT_TRANS:
 803		ASSERT(current->journal_info == NULL);
 804		/*
 805		 * We don't want to start a new transaction, just attach to the
 806		 * current one or wait it fully commits in case its commit is
 807		 * happening at the moment. Note: we don't use a nostart join
 808		 * because that does not wait for a transaction to fully commit
 809		 * (only for it to be unblocked, state TRANS_STATE_UNBLOCKED).
 810		 */
 811		trans = btrfs_attach_transaction_barrier(root);
 812		if (IS_ERR(trans)) {
 813			ret = PTR_ERR(trans);
 814			if (ret == -ENOENT)
 815				ret = 0;
 816			break;
 817		}
 818		ret = btrfs_commit_transaction(trans);
 819		break;
 820	default:
 821		ret = -ENOSPC;
 822		break;
 823	}
 824
 825	trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
 826				ret, for_preempt);
 827	return;
 828}
 829
 830static inline u64
 831btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 832				 struct btrfs_space_info *space_info)
 833{
 834	u64 used;
 835	u64 avail;
 836	u64 to_reclaim = space_info->reclaim_size;
 837
 838	lockdep_assert_held(&space_info->lock);
 839
 840	avail = calc_available_free_space(fs_info, space_info,
 841					  BTRFS_RESERVE_FLUSH_ALL);
 842	used = btrfs_space_info_used(space_info, true);
 843
 844	/*
 845	 * We may be flushing because suddenly we have less space than we had
 846	 * before, and now we're well over-committed based on our current free
 847	 * space.  If that's the case add in our overage so we make sure to put
 848	 * appropriate pressure on the flushing state machine.
 849	 */
 850	if (space_info->total_bytes + avail < used)
 851		to_reclaim += used - (space_info->total_bytes + avail);
 852
 853	return to_reclaim;
 854}
 855
 856static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 857				    struct btrfs_space_info *space_info)
 858{
 859	const u64 global_rsv_size = btrfs_block_rsv_reserved(&fs_info->global_block_rsv);
 860	u64 ordered, delalloc;
 861	u64 thresh;
 862	u64 used;
 863
 864	thresh = mult_perc(space_info->total_bytes, 90);
 865
 866	lockdep_assert_held(&space_info->lock);
 867
 868	/* If we're just plain full then async reclaim just slows us down. */
 869	if ((space_info->bytes_used + space_info->bytes_reserved +
 870	     global_rsv_size) >= thresh)
 871		return false;
 872
 873	used = space_info->bytes_may_use + space_info->bytes_pinned;
 874
 875	/* The total flushable belongs to the global rsv, don't flush. */
 876	if (global_rsv_size >= used)
 877		return false;
 878
 879	/*
 880	 * 128MiB is 1/4 of the maximum global rsv size.  If we have less than
 881	 * that devoted to other reservations then there's no sense in flushing,
 882	 * we don't have a lot of things that need flushing.
 883	 */
 884	if (used - global_rsv_size <= SZ_128M)
 885		return false;
 886
 887	/*
 888	 * We have tickets queued, bail so we don't compete with the async
 889	 * flushers.
 890	 */
 891	if (space_info->reclaim_size)
 892		return false;
 893
 894	/*
 895	 * If we have over half of the free space occupied by reservations or
 896	 * pinned then we want to start flushing.
 897	 *
 898	 * We do not do the traditional thing here, which is to say
 899	 *
 900	 *   if (used >= ((total_bytes + avail) / 2))
 901	 *     return 1;
 902	 *
 903	 * because this doesn't quite work how we want.  If we had more than 50%
 904	 * of the space_info used by bytes_used and we had 0 available we'd just
 905	 * constantly run the background flusher.  Instead we want it to kick in
 906	 * if our reclaimable space exceeds our clamped free space.
 907	 *
 908	 * Our clamping range is 2^1 -> 2^8.  Practically speaking that means
 909	 * the following:
 910	 *
 911	 * Amount of RAM        Minimum threshold       Maximum threshold
 912	 *
 913	 *        256GiB                     1GiB                  128GiB
 914	 *        128GiB                   512MiB                   64GiB
 915	 *         64GiB                   256MiB                   32GiB
 916	 *         32GiB                   128MiB                   16GiB
 917	 *         16GiB                    64MiB                    8GiB
 918	 *
 919	 * These are the range our thresholds will fall in, corresponding to how
 920	 * much delalloc we need for the background flusher to kick in.
 921	 */
 922
 923	thresh = calc_available_free_space(fs_info, space_info,
 924					   BTRFS_RESERVE_FLUSH_ALL);
 925	used = space_info->bytes_used + space_info->bytes_reserved +
 926	       space_info->bytes_readonly + global_rsv_size;
 927	if (used < space_info->total_bytes)
 928		thresh += space_info->total_bytes - used;
 929	thresh >>= space_info->clamp;
 930
 931	used = space_info->bytes_pinned;
 932
 933	/*
 934	 * If we have more ordered bytes than delalloc bytes then we're either
 935	 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
 936	 * around.  Preemptive flushing is only useful in that it can free up
 937	 * space before tickets need to wait for things to finish.  In the case
 938	 * of ordered extents, preemptively waiting on ordered extents gets us
 939	 * nothing, if our reservations are tied up in ordered extents we'll
 940	 * simply have to slow down writers by forcing them to wait on ordered
 941	 * extents.
 942	 *
 943	 * In the case that ordered is larger than delalloc, only include the
 944	 * block reserves that we would actually be able to directly reclaim
 945	 * from.  In this case if we're heavy on metadata operations this will
 946	 * clearly be heavy enough to warrant preemptive flushing.  In the case
 947	 * of heavy DIO or ordered reservations, preemptive flushing will just
 948	 * waste time and cause us to slow down.
 949	 *
 950	 * We want to make sure we truly are maxed out on ordered however, so
 951	 * cut ordered in half, and if it's still higher than delalloc then we
 952	 * can keep flushing.  This is to avoid the case where we start
 953	 * flushing, and now delalloc == ordered and we stop preemptively
 954	 * flushing when we could still have several gigs of delalloc to flush.
 955	 */
 956	ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
 957	delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
 958	if (ordered >= delalloc)
 959		used += btrfs_block_rsv_reserved(&fs_info->delayed_refs_rsv) +
 960			btrfs_block_rsv_reserved(&fs_info->delayed_block_rsv);
 961	else
 962		used += space_info->bytes_may_use - global_rsv_size;
 963
 964	return (used >= thresh && !btrfs_fs_closing(fs_info) &&
 965		!test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
 966}
 967
 968static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
 969				  struct btrfs_space_info *space_info,
 970				  struct reserve_ticket *ticket)
 971{
 972	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
 973	u64 min_bytes;
 974
 975	if (!ticket->steal)
 976		return false;
 977
 978	if (global_rsv->space_info != space_info)
 979		return false;
 980
 981	spin_lock(&global_rsv->lock);
 982	min_bytes = mult_perc(global_rsv->size, 10);
 983	if (global_rsv->reserved < min_bytes + ticket->bytes) {
 984		spin_unlock(&global_rsv->lock);
 985		return false;
 986	}
 987	global_rsv->reserved -= ticket->bytes;
 988	remove_ticket(space_info, ticket);
 989	ticket->bytes = 0;
 990	wake_up(&ticket->wait);
 991	space_info->tickets_id++;
 992	if (global_rsv->reserved < global_rsv->size)
 993		global_rsv->full = 0;
 994	spin_unlock(&global_rsv->lock);
 995
 996	return true;
 997}
 998
 999/*
1000 * We've exhausted our flushing, start failing tickets.
1001 *
1002 * @fs_info - fs_info for this fs
1003 * @space_info - the space info we were flushing
1004 *
1005 * We call this when we've exhausted our flushing ability and haven't made
1006 * progress in satisfying tickets.  The reservation code handles tickets in
1007 * order, so if there is a large ticket first and then smaller ones we could
1008 * very well satisfy the smaller tickets.  This will attempt to wake up any
1009 * tickets in the list to catch this case.
1010 *
1011 * This function returns true if it was able to make progress by clearing out
1012 * other tickets, or if it stumbles across a ticket that was smaller than the
1013 * first ticket.
1014 */
1015static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
1016				   struct btrfs_space_info *space_info)
1017{
1018	struct reserve_ticket *ticket;
1019	u64 tickets_id = space_info->tickets_id;
1020	const bool aborted = BTRFS_FS_ERROR(fs_info);
1021
1022	trace_btrfs_fail_all_tickets(fs_info, space_info);
1023
1024	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
1025		btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
1026		__btrfs_dump_space_info(fs_info, space_info);
1027	}
1028
1029	while (!list_empty(&space_info->tickets) &&
1030	       tickets_id == space_info->tickets_id) {
1031		ticket = list_first_entry(&space_info->tickets,
1032					  struct reserve_ticket, list);
1033
1034		if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket))
1035			return true;
1036
1037		if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1038			btrfs_info(fs_info, "failing ticket with %llu bytes",
1039				   ticket->bytes);
1040
1041		remove_ticket(space_info, ticket);
1042		if (aborted)
1043			ticket->error = -EIO;
1044		else
1045			ticket->error = -ENOSPC;
1046		wake_up(&ticket->wait);
1047
1048		/*
1049		 * We're just throwing tickets away, so more flushing may not
1050		 * trip over btrfs_try_granting_tickets, so we need to call it
1051		 * here to see if we can make progress with the next ticket in
1052		 * the list.
1053		 */
1054		if (!aborted)
1055			btrfs_try_granting_tickets(fs_info, space_info);
1056	}
1057	return (tickets_id != space_info->tickets_id);
1058}
1059
1060/*
1061 * This is for normal flushers, we can wait all goddamned day if we want to.  We
1062 * will loop and continuously try to flush as long as we are making progress.
1063 * We count progress as clearing off tickets each time we have to loop.
1064 */
1065static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
1066{
1067	struct btrfs_fs_info *fs_info;
1068	struct btrfs_space_info *space_info;
1069	u64 to_reclaim;
1070	enum btrfs_flush_state flush_state;
1071	int commit_cycles = 0;
1072	u64 last_tickets_id;
1073
1074	fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
1075	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1076
1077	spin_lock(&space_info->lock);
1078	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1079	if (!to_reclaim) {
1080		space_info->flush = 0;
1081		spin_unlock(&space_info->lock);
1082		return;
1083	}
1084	last_tickets_id = space_info->tickets_id;
1085	spin_unlock(&space_info->lock);
1086
1087	flush_state = FLUSH_DELAYED_ITEMS_NR;
1088	do {
1089		flush_space(fs_info, space_info, to_reclaim, flush_state, false);
1090		spin_lock(&space_info->lock);
1091		if (list_empty(&space_info->tickets)) {
1092			space_info->flush = 0;
1093			spin_unlock(&space_info->lock);
1094			return;
1095		}
1096		to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1097							      space_info);
1098		if (last_tickets_id == space_info->tickets_id) {
1099			flush_state++;
1100		} else {
1101			last_tickets_id = space_info->tickets_id;
1102			flush_state = FLUSH_DELAYED_ITEMS_NR;
1103			if (commit_cycles)
1104				commit_cycles--;
1105		}
1106
1107		/*
1108		 * We do not want to empty the system of delalloc unless we're
1109		 * under heavy pressure, so allow one trip through the flushing
1110		 * logic before we start doing a FLUSH_DELALLOC_FULL.
1111		 */
1112		if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
1113			flush_state++;
1114
1115		/*
1116		 * We don't want to force a chunk allocation until we've tried
1117		 * pretty hard to reclaim space.  Think of the case where we
1118		 * freed up a bunch of space and so have a lot of pinned space
1119		 * to reclaim.  We would rather use that than possibly create a
1120		 * underutilized metadata chunk.  So if this is our first run
1121		 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1122		 * commit the transaction.  If nothing has changed the next go
1123		 * around then we can force a chunk allocation.
1124		 */
1125		if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1126			flush_state++;
1127
1128		if (flush_state > COMMIT_TRANS) {
1129			commit_cycles++;
1130			if (commit_cycles > 2) {
1131				if (maybe_fail_all_tickets(fs_info, space_info)) {
1132					flush_state = FLUSH_DELAYED_ITEMS_NR;
1133					commit_cycles--;
1134				} else {
1135					space_info->flush = 0;
1136				}
1137			} else {
1138				flush_state = FLUSH_DELAYED_ITEMS_NR;
1139			}
1140		}
1141		spin_unlock(&space_info->lock);
1142	} while (flush_state <= COMMIT_TRANS);
1143}
1144
1145/*
1146 * This handles pre-flushing of metadata space before we get to the point that
1147 * we need to start blocking threads on tickets.  The logic here is different
1148 * from the other flush paths because it doesn't rely on tickets to tell us how
1149 * much we need to flush, instead it attempts to keep us below the 80% full
1150 * watermark of space by flushing whichever reservation pool is currently the
1151 * largest.
1152 */
1153static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
1154{
1155	struct btrfs_fs_info *fs_info;
1156	struct btrfs_space_info *space_info;
1157	struct btrfs_block_rsv *delayed_block_rsv;
1158	struct btrfs_block_rsv *delayed_refs_rsv;
1159	struct btrfs_block_rsv *global_rsv;
1160	struct btrfs_block_rsv *trans_rsv;
1161	int loops = 0;
1162
1163	fs_info = container_of(work, struct btrfs_fs_info,
1164			       preempt_reclaim_work);
1165	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1166	delayed_block_rsv = &fs_info->delayed_block_rsv;
1167	delayed_refs_rsv = &fs_info->delayed_refs_rsv;
1168	global_rsv = &fs_info->global_block_rsv;
1169	trans_rsv = &fs_info->trans_block_rsv;
1170
1171	spin_lock(&space_info->lock);
1172	while (need_preemptive_reclaim(fs_info, space_info)) {
1173		enum btrfs_flush_state flush;
1174		u64 delalloc_size = 0;
1175		u64 to_reclaim, block_rsv_size;
1176		const u64 global_rsv_size = btrfs_block_rsv_reserved(global_rsv);
1177
1178		loops++;
1179
1180		/*
1181		 * We don't have a precise counter for the metadata being
1182		 * reserved for delalloc, so we'll approximate it by subtracting
1183		 * out the block rsv's space from the bytes_may_use.  If that
1184		 * amount is higher than the individual reserves, then we can
1185		 * assume it's tied up in delalloc reservations.
1186		 */
1187		block_rsv_size = global_rsv_size +
1188			btrfs_block_rsv_reserved(delayed_block_rsv) +
1189			btrfs_block_rsv_reserved(delayed_refs_rsv) +
1190			btrfs_block_rsv_reserved(trans_rsv);
1191		if (block_rsv_size < space_info->bytes_may_use)
1192			delalloc_size = space_info->bytes_may_use - block_rsv_size;
1193
1194		/*
1195		 * We don't want to include the global_rsv in our calculation,
1196		 * because that's space we can't touch.  Subtract it from the
1197		 * block_rsv_size for the next checks.
1198		 */
1199		block_rsv_size -= global_rsv_size;
1200
1201		/*
1202		 * We really want to avoid flushing delalloc too much, as it
1203		 * could result in poor allocation patterns, so only flush it if
1204		 * it's larger than the rest of the pools combined.
1205		 */
1206		if (delalloc_size > block_rsv_size) {
1207			to_reclaim = delalloc_size;
1208			flush = FLUSH_DELALLOC;
1209		} else if (space_info->bytes_pinned >
1210			   (btrfs_block_rsv_reserved(delayed_block_rsv) +
1211			    btrfs_block_rsv_reserved(delayed_refs_rsv))) {
1212			to_reclaim = space_info->bytes_pinned;
1213			flush = COMMIT_TRANS;
1214		} else if (btrfs_block_rsv_reserved(delayed_block_rsv) >
1215			   btrfs_block_rsv_reserved(delayed_refs_rsv)) {
1216			to_reclaim = btrfs_block_rsv_reserved(delayed_block_rsv);
1217			flush = FLUSH_DELAYED_ITEMS_NR;
1218		} else {
1219			to_reclaim = btrfs_block_rsv_reserved(delayed_refs_rsv);
1220			flush = FLUSH_DELAYED_REFS_NR;
1221		}
1222
1223		spin_unlock(&space_info->lock);
1224
1225		/*
1226		 * We don't want to reclaim everything, just a portion, so scale
1227		 * down the to_reclaim by 1/4.  If it takes us down to 0,
1228		 * reclaim 1 items worth.
1229		 */
1230		to_reclaim >>= 2;
1231		if (!to_reclaim)
1232			to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1233		flush_space(fs_info, space_info, to_reclaim, flush, true);
1234		cond_resched();
1235		spin_lock(&space_info->lock);
1236	}
1237
1238	/* We only went through once, back off our clamping. */
1239	if (loops == 1 && !space_info->reclaim_size)
1240		space_info->clamp = max(1, space_info->clamp - 1);
1241	trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1242	spin_unlock(&space_info->lock);
1243}
1244
1245/*
1246 * FLUSH_DELALLOC_WAIT:
1247 *   Space is freed from flushing delalloc in one of two ways.
1248 *
1249 *   1) compression is on and we allocate less space than we reserved
1250 *   2) we are overwriting existing space
1251 *
1252 *   For #1 that extra space is reclaimed as soon as the delalloc pages are
1253 *   COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1254 *   length to ->bytes_reserved, and subtracts the reserved space from
1255 *   ->bytes_may_use.
1256 *
1257 *   For #2 this is trickier.  Once the ordered extent runs we will drop the
1258 *   extent in the range we are overwriting, which creates a delayed ref for
1259 *   that freed extent.  This however is not reclaimed until the transaction
1260 *   commits, thus the next stages.
1261 *
1262 * RUN_DELAYED_IPUTS
1263 *   If we are freeing inodes, we want to make sure all delayed iputs have
1264 *   completed, because they could have been on an inode with i_nlink == 0, and
1265 *   thus have been truncated and freed up space.  But again this space is not
1266 *   immediately re-usable, it comes in the form of a delayed ref, which must be
1267 *   run and then the transaction must be committed.
1268 *
1269 * COMMIT_TRANS
1270 *   This is where we reclaim all of the pinned space generated by running the
1271 *   iputs
1272 *
1273 * ALLOC_CHUNK_FORCE
1274 *   For data we start with alloc chunk force, however we could have been full
1275 *   before, and then the transaction commit could have freed new block groups,
1276 *   so if we now have space to allocate do the force chunk allocation.
1277 */
1278static const enum btrfs_flush_state data_flush_states[] = {
1279	FLUSH_DELALLOC_FULL,
1280	RUN_DELAYED_IPUTS,
1281	COMMIT_TRANS,
1282	ALLOC_CHUNK_FORCE,
1283};
1284
1285static void btrfs_async_reclaim_data_space(struct work_struct *work)
1286{
1287	struct btrfs_fs_info *fs_info;
1288	struct btrfs_space_info *space_info;
1289	u64 last_tickets_id;
1290	enum btrfs_flush_state flush_state = 0;
1291
1292	fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1293	space_info = fs_info->data_sinfo;
1294
1295	spin_lock(&space_info->lock);
1296	if (list_empty(&space_info->tickets)) {
1297		space_info->flush = 0;
1298		spin_unlock(&space_info->lock);
1299		return;
1300	}
1301	last_tickets_id = space_info->tickets_id;
1302	spin_unlock(&space_info->lock);
1303
1304	while (!space_info->full) {
1305		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1306		spin_lock(&space_info->lock);
1307		if (list_empty(&space_info->tickets)) {
1308			space_info->flush = 0;
1309			spin_unlock(&space_info->lock);
1310			return;
1311		}
1312
1313		/* Something happened, fail everything and bail. */
1314		if (BTRFS_FS_ERROR(fs_info))
1315			goto aborted_fs;
1316		last_tickets_id = space_info->tickets_id;
1317		spin_unlock(&space_info->lock);
1318	}
1319
1320	while (flush_state < ARRAY_SIZE(data_flush_states)) {
1321		flush_space(fs_info, space_info, U64_MAX,
1322			    data_flush_states[flush_state], false);
1323		spin_lock(&space_info->lock);
1324		if (list_empty(&space_info->tickets)) {
1325			space_info->flush = 0;
1326			spin_unlock(&space_info->lock);
1327			return;
1328		}
1329
1330		if (last_tickets_id == space_info->tickets_id) {
1331			flush_state++;
1332		} else {
1333			last_tickets_id = space_info->tickets_id;
1334			flush_state = 0;
1335		}
1336
1337		if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1338			if (space_info->full) {
1339				if (maybe_fail_all_tickets(fs_info, space_info))
1340					flush_state = 0;
1341				else
1342					space_info->flush = 0;
1343			} else {
1344				flush_state = 0;
1345			}
1346
1347			/* Something happened, fail everything and bail. */
1348			if (BTRFS_FS_ERROR(fs_info))
1349				goto aborted_fs;
1350
1351		}
1352		spin_unlock(&space_info->lock);
1353	}
1354	return;
1355
1356aborted_fs:
1357	maybe_fail_all_tickets(fs_info, space_info);
1358	space_info->flush = 0;
1359	spin_unlock(&space_info->lock);
1360}
1361
1362void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1363{
1364	INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1365	INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1366	INIT_WORK(&fs_info->preempt_reclaim_work,
1367		  btrfs_preempt_reclaim_metadata_space);
1368}
1369
1370static const enum btrfs_flush_state priority_flush_states[] = {
1371	FLUSH_DELAYED_ITEMS_NR,
1372	FLUSH_DELAYED_ITEMS,
1373	ALLOC_CHUNK,
1374};
1375
1376static const enum btrfs_flush_state evict_flush_states[] = {
1377	FLUSH_DELAYED_ITEMS_NR,
1378	FLUSH_DELAYED_ITEMS,
1379	FLUSH_DELAYED_REFS_NR,
1380	FLUSH_DELAYED_REFS,
1381	FLUSH_DELALLOC,
1382	FLUSH_DELALLOC_WAIT,
1383	FLUSH_DELALLOC_FULL,
1384	ALLOC_CHUNK,
1385	COMMIT_TRANS,
1386};
1387
1388static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1389				struct btrfs_space_info *space_info,
1390				struct reserve_ticket *ticket,
1391				const enum btrfs_flush_state *states,
1392				int states_nr)
1393{
1394	u64 to_reclaim;
1395	int flush_state = 0;
1396
1397	spin_lock(&space_info->lock);
1398	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1399	/*
1400	 * This is the priority reclaim path, so to_reclaim could be >0 still
1401	 * because we may have only satisfied the priority tickets and still
1402	 * left non priority tickets on the list.  We would then have
1403	 * to_reclaim but ->bytes == 0.
1404	 */
1405	if (ticket->bytes == 0) {
1406		spin_unlock(&space_info->lock);
1407		return;
1408	}
1409
1410	while (flush_state < states_nr) {
1411		spin_unlock(&space_info->lock);
1412		flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1413			    false);
1414		flush_state++;
1415		spin_lock(&space_info->lock);
1416		if (ticket->bytes == 0) {
1417			spin_unlock(&space_info->lock);
1418			return;
1419		}
1420	}
1421
1422	/*
1423	 * Attempt to steal from the global rsv if we can, except if the fs was
1424	 * turned into error mode due to a transaction abort when flushing space
1425	 * above, in that case fail with the abort error instead of returning
1426	 * success to the caller if we can steal from the global rsv - this is
1427	 * just to have caller fail immeditelly instead of later when trying to
1428	 * modify the fs, making it easier to debug -ENOSPC problems.
1429	 */
1430	if (BTRFS_FS_ERROR(fs_info)) {
1431		ticket->error = BTRFS_FS_ERROR(fs_info);
1432		remove_ticket(space_info, ticket);
1433	} else if (!steal_from_global_rsv(fs_info, space_info, ticket)) {
1434		ticket->error = -ENOSPC;
1435		remove_ticket(space_info, ticket);
1436	}
1437
1438	/*
1439	 * We must run try_granting_tickets here because we could be a large
1440	 * ticket in front of a smaller ticket that can now be satisfied with
1441	 * the available space.
1442	 */
1443	btrfs_try_granting_tickets(fs_info, space_info);
1444	spin_unlock(&space_info->lock);
1445}
1446
1447static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1448					struct btrfs_space_info *space_info,
1449					struct reserve_ticket *ticket)
1450{
1451	spin_lock(&space_info->lock);
1452
1453	/* We could have been granted before we got here. */
1454	if (ticket->bytes == 0) {
1455		spin_unlock(&space_info->lock);
1456		return;
1457	}
1458
1459	while (!space_info->full) {
1460		spin_unlock(&space_info->lock);
1461		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1462		spin_lock(&space_info->lock);
1463		if (ticket->bytes == 0) {
1464			spin_unlock(&space_info->lock);
1465			return;
1466		}
1467	}
1468
1469	ticket->error = -ENOSPC;
1470	remove_ticket(space_info, ticket);
1471	btrfs_try_granting_tickets(fs_info, space_info);
1472	spin_unlock(&space_info->lock);
1473}
1474
1475static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1476				struct btrfs_space_info *space_info,
1477				struct reserve_ticket *ticket)
1478
1479{
1480	DEFINE_WAIT(wait);
1481	int ret = 0;
1482
1483	spin_lock(&space_info->lock);
1484	while (ticket->bytes > 0 && ticket->error == 0) {
1485		ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1486		if (ret) {
1487			/*
1488			 * Delete us from the list. After we unlock the space
1489			 * info, we don't want the async reclaim job to reserve
1490			 * space for this ticket. If that would happen, then the
1491			 * ticket's task would not known that space was reserved
1492			 * despite getting an error, resulting in a space leak
1493			 * (bytes_may_use counter of our space_info).
1494			 */
1495			remove_ticket(space_info, ticket);
1496			ticket->error = -EINTR;
1497			break;
1498		}
1499		spin_unlock(&space_info->lock);
1500
1501		schedule();
1502
1503		finish_wait(&ticket->wait, &wait);
1504		spin_lock(&space_info->lock);
1505	}
1506	spin_unlock(&space_info->lock);
1507}
1508
1509/*
1510 * Do the appropriate flushing and waiting for a ticket.
1511 *
1512 * @fs_info:    the filesystem
1513 * @space_info: space info for the reservation
1514 * @ticket:     ticket for the reservation
1515 * @start_ns:   timestamp when the reservation started
1516 * @orig_bytes: amount of bytes originally reserved
1517 * @flush:      how much we can flush
1518 *
1519 * This does the work of figuring out how to flush for the ticket, waiting for
1520 * the reservation, and returning the appropriate error if there is one.
1521 */
1522static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1523				 struct btrfs_space_info *space_info,
1524				 struct reserve_ticket *ticket,
1525				 u64 start_ns, u64 orig_bytes,
1526				 enum btrfs_reserve_flush_enum flush)
1527{
1528	int ret;
1529
1530	switch (flush) {
1531	case BTRFS_RESERVE_FLUSH_DATA:
1532	case BTRFS_RESERVE_FLUSH_ALL:
1533	case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1534		wait_reserve_ticket(fs_info, space_info, ticket);
1535		break;
1536	case BTRFS_RESERVE_FLUSH_LIMIT:
1537		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1538						priority_flush_states,
1539						ARRAY_SIZE(priority_flush_states));
1540		break;
1541	case BTRFS_RESERVE_FLUSH_EVICT:
1542		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1543						evict_flush_states,
1544						ARRAY_SIZE(evict_flush_states));
1545		break;
1546	case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1547		priority_reclaim_data_space(fs_info, space_info, ticket);
1548		break;
1549	default:
1550		ASSERT(0);
1551		break;
1552	}
1553
1554	ret = ticket->error;
1555	ASSERT(list_empty(&ticket->list));
1556	/*
1557	 * Check that we can't have an error set if the reservation succeeded,
1558	 * as that would confuse tasks and lead them to error out without
1559	 * releasing reserved space (if an error happens the expectation is that
1560	 * space wasn't reserved at all).
1561	 */
1562	ASSERT(!(ticket->bytes == 0 && ticket->error));
1563	trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1564				   start_ns, flush, ticket->error);
1565	return ret;
1566}
1567
1568/*
1569 * This returns true if this flush state will go through the ordinary flushing
1570 * code.
1571 */
1572static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1573{
1574	return	(flush == BTRFS_RESERVE_FLUSH_ALL) ||
1575		(flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1576}
1577
1578static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1579				       struct btrfs_space_info *space_info)
1580{
1581	u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1582	u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1583
1584	/*
1585	 * If we're heavy on ordered operations then clamping won't help us.  We
1586	 * need to clamp specifically to keep up with dirty'ing buffered
1587	 * writers, because there's not a 1:1 correlation of writing delalloc
1588	 * and freeing space, like there is with flushing delayed refs or
1589	 * delayed nodes.  If we're already more ordered than delalloc then
1590	 * we're keeping up, otherwise we aren't and should probably clamp.
1591	 */
1592	if (ordered < delalloc)
1593		space_info->clamp = min(space_info->clamp + 1, 8);
1594}
1595
1596static inline bool can_steal(enum btrfs_reserve_flush_enum flush)
1597{
1598	return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1599		flush == BTRFS_RESERVE_FLUSH_EVICT);
1600}
1601
1602/*
1603 * NO_FLUSH and FLUSH_EMERGENCY don't want to create a ticket, they just want to
1604 * fail as quickly as possible.
1605 */
1606static inline bool can_ticket(enum btrfs_reserve_flush_enum flush)
1607{
1608	return (flush != BTRFS_RESERVE_NO_FLUSH &&
1609		flush != BTRFS_RESERVE_FLUSH_EMERGENCY);
1610}
1611
1612/*
1613 * Try to reserve bytes from the block_rsv's space.
1614 *
1615 * @fs_info:    the filesystem
1616 * @space_info: space info we want to allocate from
1617 * @orig_bytes: number of bytes we want
1618 * @flush:      whether or not we can flush to make our reservation
1619 *
1620 * This will reserve orig_bytes number of bytes from the space info associated
1621 * with the block_rsv.  If there is not enough space it will make an attempt to
1622 * flush out space to make room.  It will do this by flushing delalloc if
1623 * possible or committing the transaction.  If flush is 0 then no attempts to
1624 * regain reservations will be made and this will fail if there is not enough
1625 * space already.
1626 */
1627static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1628			   struct btrfs_space_info *space_info, u64 orig_bytes,
1629			   enum btrfs_reserve_flush_enum flush)
1630{
1631	struct work_struct *async_work;
1632	struct reserve_ticket ticket;
1633	u64 start_ns = 0;
1634	u64 used;
1635	int ret = -ENOSPC;
1636	bool pending_tickets;
1637
1638	ASSERT(orig_bytes);
1639	/*
1640	 * If have a transaction handle (current->journal_info != NULL), then
1641	 * the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor
1642	 * BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those
1643	 * flushing methods can trigger transaction commits.
1644	 */
1645	if (current->journal_info) {
1646		/* One assert per line for easier debugging. */
1647		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL);
1648		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL);
1649		ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT);
1650	}
1651
1652	if (flush == BTRFS_RESERVE_FLUSH_DATA)
1653		async_work = &fs_info->async_data_reclaim_work;
1654	else
1655		async_work = &fs_info->async_reclaim_work;
1656
1657	spin_lock(&space_info->lock);
1658	used = btrfs_space_info_used(space_info, true);
1659
1660	/*
1661	 * We don't want NO_FLUSH allocations to jump everybody, they can
1662	 * generally handle ENOSPC in a different way, so treat them the same as
1663	 * normal flushers when it comes to skipping pending tickets.
1664	 */
1665	if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1666		pending_tickets = !list_empty(&space_info->tickets) ||
1667			!list_empty(&space_info->priority_tickets);
1668	else
1669		pending_tickets = !list_empty(&space_info->priority_tickets);
1670
1671	/*
1672	 * Carry on if we have enough space (short-circuit) OR call
1673	 * can_overcommit() to ensure we can overcommit to continue.
1674	 */
1675	if (!pending_tickets &&
1676	    ((used + orig_bytes <= space_info->total_bytes) ||
1677	     btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1678		btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1679						      orig_bytes);
1680		ret = 0;
1681	}
1682
1683	/*
1684	 * Things are dire, we need to make a reservation so we don't abort.  We
1685	 * will let this reservation go through as long as we have actual space
1686	 * left to allocate for the block.
1687	 */
1688	if (ret && unlikely(flush == BTRFS_RESERVE_FLUSH_EMERGENCY)) {
1689		used = btrfs_space_info_used(space_info, false);
1690		if (used + orig_bytes <= space_info->total_bytes) {
1691			btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1692							      orig_bytes);
1693			ret = 0;
1694		}
1695	}
1696
1697	/*
1698	 * If we couldn't make a reservation then setup our reservation ticket
1699	 * and kick the async worker if it's not already running.
1700	 *
1701	 * If we are a priority flusher then we just need to add our ticket to
1702	 * the list and we will do our own flushing further down.
1703	 */
1704	if (ret && can_ticket(flush)) {
1705		ticket.bytes = orig_bytes;
1706		ticket.error = 0;
1707		space_info->reclaim_size += ticket.bytes;
1708		init_waitqueue_head(&ticket.wait);
1709		ticket.steal = can_steal(flush);
1710		if (trace_btrfs_reserve_ticket_enabled())
1711			start_ns = ktime_get_ns();
1712
1713		if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1714		    flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1715		    flush == BTRFS_RESERVE_FLUSH_DATA) {
1716			list_add_tail(&ticket.list, &space_info->tickets);
1717			if (!space_info->flush) {
1718				/*
1719				 * We were forced to add a reserve ticket, so
1720				 * our preemptive flushing is unable to keep
1721				 * up.  Clamp down on the threshold for the
1722				 * preemptive flushing in order to keep up with
1723				 * the workload.
1724				 */
1725				maybe_clamp_preempt(fs_info, space_info);
1726
1727				space_info->flush = 1;
1728				trace_btrfs_trigger_flush(fs_info,
1729							  space_info->flags,
1730							  orig_bytes, flush,
1731							  "enospc");
1732				queue_work(system_unbound_wq, async_work);
1733			}
1734		} else {
1735			list_add_tail(&ticket.list,
1736				      &space_info->priority_tickets);
1737		}
1738	} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1739		/*
1740		 * We will do the space reservation dance during log replay,
1741		 * which means we won't have fs_info->fs_root set, so don't do
1742		 * the async reclaim as we will panic.
1743		 */
1744		if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1745		    !work_busy(&fs_info->preempt_reclaim_work) &&
1746		    need_preemptive_reclaim(fs_info, space_info)) {
1747			trace_btrfs_trigger_flush(fs_info, space_info->flags,
1748						  orig_bytes, flush, "preempt");
1749			queue_work(system_unbound_wq,
1750				   &fs_info->preempt_reclaim_work);
1751		}
1752	}
1753	spin_unlock(&space_info->lock);
1754	if (!ret || !can_ticket(flush))
1755		return ret;
1756
1757	return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1758				     orig_bytes, flush);
1759}
1760
1761/*
1762 * Try to reserve metadata bytes from the block_rsv's space.
1763 *
1764 * @fs_info:    the filesystem
1765 * @space_info: the space_info we're allocating for
1766 * @orig_bytes: number of bytes we want
1767 * @flush:      whether or not we can flush to make our reservation
1768 *
1769 * This will reserve orig_bytes number of bytes from the space info associated
1770 * with the block_rsv.  If there is not enough space it will make an attempt to
1771 * flush out space to make room.  It will do this by flushing delalloc if
1772 * possible or committing the transaction.  If flush is 0 then no attempts to
1773 * regain reservations will be made and this will fail if there is not enough
1774 * space already.
1775 */
1776int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1777				 struct btrfs_space_info *space_info,
1778				 u64 orig_bytes,
1779				 enum btrfs_reserve_flush_enum flush)
1780{
1781	int ret;
1782
1783	ret = __reserve_bytes(fs_info, space_info, orig_bytes, flush);
1784	if (ret == -ENOSPC) {
1785		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1786					      space_info->flags, orig_bytes, 1);
1787
1788		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1789			btrfs_dump_space_info(fs_info, space_info, orig_bytes, 0);
1790	}
1791	return ret;
1792}
1793
1794/*
1795 * Try to reserve data bytes for an allocation.
1796 *
1797 * @fs_info: the filesystem
1798 * @bytes:   number of bytes we need
1799 * @flush:   how we are allowed to flush
1800 *
1801 * This will reserve bytes from the data space info.  If there is not enough
1802 * space then we will attempt to flush space as specified by flush.
1803 */
1804int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1805			     enum btrfs_reserve_flush_enum flush)
1806{
1807	struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1808	int ret;
1809
1810	ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1811	       flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE ||
1812	       flush == BTRFS_RESERVE_NO_FLUSH);
1813	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1814
1815	ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1816	if (ret == -ENOSPC) {
1817		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1818					      data_sinfo->flags, bytes, 1);
1819		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1820			btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
1821	}
1822	return ret;
1823}
1824
1825/* Dump all the space infos when we abort a transaction due to ENOSPC. */
1826__cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
1827{
1828	struct btrfs_space_info *space_info;
1829
1830	btrfs_info(fs_info, "dumping space info:");
1831	list_for_each_entry(space_info, &fs_info->space_info, list) {
1832		spin_lock(&space_info->lock);
1833		__btrfs_dump_space_info(fs_info, space_info);
1834		spin_unlock(&space_info->lock);
1835	}
1836	dump_global_block_rsv(fs_info);
1837}
1838
1839/*
1840 * Account the unused space of all the readonly block group in the space_info.
1841 * takes mirrors into account.
1842 */
1843u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
1844{
1845	struct btrfs_block_group *block_group;
1846	u64 free_bytes = 0;
1847	int factor;
1848
1849	/* It's df, we don't care if it's racy */
1850	if (list_empty(&sinfo->ro_bgs))
1851		return 0;
1852
1853	spin_lock(&sinfo->lock);
1854	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
1855		spin_lock(&block_group->lock);
1856
1857		if (!block_group->ro) {
1858			spin_unlock(&block_group->lock);
1859			continue;
1860		}
1861
1862		factor = btrfs_bg_type_to_factor(block_group->flags);
1863		free_bytes += (block_group->length -
1864			       block_group->used) * factor;
1865
1866		spin_unlock(&block_group->lock);
1867	}
1868	spin_unlock(&sinfo->lock);
1869
1870	return free_bytes;
1871}