1// SPDX-License-Identifier: GPL-2.0
   2
   3#include "linux/spinlock.h"
   4#include <linux/minmax.h>
   5#include "misc.h"
   6#include "ctree.h"
   7#include "space-info.h"
   8#include "sysfs.h"
   9#include "volumes.h"
  10#include "free-space-cache.h"
  11#include "ordered-data.h"
  12#include "transaction.h"
  13#include "block-group.h"
  14#include "fs.h"
  15#include "accessors.h"
  16#include "extent-tree.h"
  17
  18/*
  19 * HOW DOES SPACE RESERVATION WORK
  20 *
  21 * If you want to know about delalloc specifically, there is a separate comment
  22 * for that with the delalloc code.  This comment is about how the whole system
  23 * works generally.
  24 *
  25 * BASIC CONCEPTS
  26 *
  27 *   1) space_info.  This is the ultimate arbiter of how much space we can use.
  28 *   There's a description of the bytes_ fields with the struct declaration,
  29 *   refer to that for specifics on each field.  Suffice it to say that for
  30 *   reservations we care about total_bytes - SUM(space_info->bytes_) when
  31 *   determining if there is space to make an allocation.  There is a space_info
  32 *   for METADATA, SYSTEM, and DATA areas.
  33 *
  34 *   2) block_rsv's.  These are basically buckets for every different type of
  35 *   metadata reservation we have.  You can see the comment in the block_rsv
  36 *   code on the rules for each type, but generally block_rsv->reserved is how
  37 *   much space is accounted for in space_info->bytes_may_use.
  38 *
  39 *   3) btrfs_calc*_size.  These are the worst case calculations we used based
  40 *   on the number of items we will want to modify.  We have one for changing
  41 *   items, and one for inserting new items.  Generally we use these helpers to
  42 *   determine the size of the block reserves, and then use the actual bytes
  43 *   values to adjust the space_info counters.
  44 *
  45 * MAKING RESERVATIONS, THE NORMAL CASE
  46 *
  47 *   We call into either btrfs_reserve_data_bytes() or
  48 *   btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
  49 *   num_bytes we want to reserve.
  50 *
  51 *   ->reserve
  52 *     space_info->bytes_may_reserve += num_bytes
  53 *
  54 *   ->extent allocation
  55 *     Call btrfs_add_reserved_bytes() which does
  56 *     space_info->bytes_may_reserve -= num_bytes
  57 *     space_info->bytes_reserved += extent_bytes
  58 *
  59 *   ->insert reference
  60 *     Call btrfs_update_block_group() which does
  61 *     space_info->bytes_reserved -= extent_bytes
  62 *     space_info->bytes_used += extent_bytes
  63 *
  64 * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
  65 *
  66 *   Assume we are unable to simply make the reservation because we do not have
  67 *   enough space
  68 *
  69 *   -> __reserve_bytes
  70 *     create a reserve_ticket with ->bytes set to our reservation, add it to
  71 *     the tail of space_info->tickets, kick async flush thread
  72 *
  73 *   ->handle_reserve_ticket
  74 *     wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
  75 *     on the ticket.
  76 *
  77 *   -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
  78 *     Flushes various things attempting to free up space.
  79 *
  80 *   -> btrfs_try_granting_tickets()
  81 *     This is called by anything that either subtracts space from
  82 *     space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
  83 *     space_info->total_bytes.  This loops through the ->priority_tickets and
  84 *     then the ->tickets list checking to see if the reservation can be
  85 *     completed.  If it can the space is added to space_info->bytes_may_use and
  86 *     the ticket is woken up.
  87 *
  88 *   -> ticket wakeup
  89 *     Check if ->bytes == 0, if it does we got our reservation and we can carry
  90 *     on, if not return the appropriate error (ENOSPC, but can be EINTR if we
  91 *     were interrupted.)
  92 *
  93 * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
  94 *
  95 *   Same as the above, except we add ourselves to the
  96 *   space_info->priority_tickets, and we do not use ticket->wait, we simply
  97 *   call flush_space() ourselves for the states that are safe for us to call
  98 *   without deadlocking and hope for the best.
  99 *
 100 * THE FLUSHING STATES
 101 *
 102 *   Generally speaking we will have two cases for each state, a "nice" state
 103 *   and a "ALL THE THINGS" state.  In btrfs we delay a lot of work in order to
 104 *   reduce the locking over head on the various trees, and even to keep from
 105 *   doing any work at all in the case of delayed refs.  Each of these delayed
 106 *   things however hold reservations, and so letting them run allows us to
 107 *   reclaim space so we can make new reservations.
 108 *
 109 *   FLUSH_DELAYED_ITEMS
 110 *     Every inode has a delayed item to update the inode.  Take a simple write
 111 *     for example, we would update the inode item at write time to update the
 112 *     mtime, and then again at finish_ordered_io() time in order to update the
 113 *     isize or bytes.  We keep these delayed items to coalesce these operations
 114 *     into a single operation done on demand.  These are an easy way to reclaim
 115 *     metadata space.
 116 *
 117 *   FLUSH_DELALLOC
 118 *     Look at the delalloc comment to get an idea of how much space is reserved
 119 *     for delayed allocation.  We can reclaim some of this space simply by
 120 *     running delalloc, but usually we need to wait for ordered extents to
 121 *     reclaim the bulk of this space.
 122 *
 123 *   FLUSH_DELAYED_REFS
 124 *     We have a block reserve for the outstanding delayed refs space, and every
 125 *     delayed ref operation holds a reservation.  Running these is a quick way
 126 *     to reclaim space, but we want to hold this until the end because COW can
 127 *     churn a lot and we can avoid making some extent tree modifications if we
 128 *     are able to delay for as long as possible.
 129 *
 130 *   ALLOC_CHUNK
 131 *     We will skip this the first time through space reservation, because of
 132 *     overcommit and we don't want to have a lot of useless metadata space when
 133 *     our worst case reservations will likely never come true.
 134 *
 135 *   RUN_DELAYED_IPUTS
 136 *     If we're freeing inodes we're likely freeing checksums, file extent
 137 *     items, and extent tree items.  Loads of space could be freed up by these
 138 *     operations, however they won't be usable until the transaction commits.
 139 *
 140 *   COMMIT_TRANS
 141 *     This will commit the transaction.  Historically we had a lot of logic
 142 *     surrounding whether or not we'd commit the transaction, but this waits born
 143 *     out of a pre-tickets era where we could end up committing the transaction
 144 *     thousands of times in a row without making progress.  Now thanks to our
 145 *     ticketing system we know if we're not making progress and can error
 146 *     everybody out after a few commits rather than burning the disk hoping for
 147 *     a different answer.
 148 *
 149 * OVERCOMMIT
 150 *
 151 *   Because we hold so many reservations for metadata we will allow you to
 152 *   reserve more space than is currently free in the currently allocate
 153 *   metadata space.  This only happens with metadata, data does not allow
 154 *   overcommitting.
 155 *
 156 *   You can see the current logic for when we allow overcommit in
 157 *   btrfs_can_overcommit(), but it only applies to unallocated space.  If there
 158 *   is no unallocated space to be had, all reservations are kept within the
 159 *   free space in the allocated metadata chunks.
 160 *
 161 *   Because of overcommitting, you generally want to use the
 162 *   btrfs_can_overcommit() logic for metadata allocations, as it does the right
 163 *   thing with or without extra unallocated space.
 164 */
 165
 166u64 __pure btrfs_space_info_used(const struct btrfs_space_info *s_info,
 167			  bool may_use_included)
 168{
 169	ASSERT(s_info);
 170	return s_info->bytes_used + s_info->bytes_reserved +
 171		s_info->bytes_pinned + s_info->bytes_readonly +
 172		s_info->bytes_zone_unusable +
 173		(may_use_included ? s_info->bytes_may_use : 0);
 174}
 175
 176/*
 177 * after adding space to the filesystem, we need to clear the full flags
 178 * on all the space infos.
 179 */
 180void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
 181{
 182	struct list_head *head = &info->space_info;
 183	struct btrfs_space_info *found;
 184
 185	list_for_each_entry(found, head, list)
 186		found->full = 0;
 187}
 188
 189/*
 190 * Block groups with more than this value (percents) of unusable space will be
 191 * scheduled for background reclaim.
 192 */
 193#define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH			(75)
 194
 195#define BTRFS_UNALLOC_BLOCK_GROUP_TARGET			(10ULL)
 196
 197/*
 198 * Calculate chunk size depending on volume type (regular or zoned).
 199 */
 200static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
 201{
 202	if (btrfs_is_zoned(fs_info))
 203		return fs_info->zone_size;
 204
 205	ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
 206
 207	if (flags & BTRFS_BLOCK_GROUP_DATA)
 208		return BTRFS_MAX_DATA_CHUNK_SIZE;
 209	else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
 210		return SZ_32M;
 211
 212	/* Handle BTRFS_BLOCK_GROUP_METADATA */
 213	if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
 214		return SZ_1G;
 215
 216	return SZ_256M;
 217}
 218
 219/*
 220 * Update default chunk size.
 221 */
 222void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
 223					u64 chunk_size)
 224{
 225	WRITE_ONCE(space_info->chunk_size, chunk_size);
 226}
 227
 228static int create_space_info(struct btrfs_fs_info *info, u64 flags)
 229{
 230
 231	struct btrfs_space_info *space_info;
 232	int i;
 233	int ret;
 234
 235	space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
 236	if (!space_info)
 237		return -ENOMEM;
 238
 239	space_info->fs_info = info;
 240	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
 241		INIT_LIST_HEAD(&space_info->block_groups[i]);
 242	init_rwsem(&space_info->groups_sem);
 243	spin_lock_init(&space_info->lock);
 244	space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
 245	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
 246	INIT_LIST_HEAD(&space_info->ro_bgs);
 247	INIT_LIST_HEAD(&space_info->tickets);
 248	INIT_LIST_HEAD(&space_info->priority_tickets);
 249	space_info->clamp = 1;
 250	btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags));
 251
 252	if (btrfs_is_zoned(info))
 253		space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH;
 254
 255	ret = btrfs_sysfs_add_space_info_type(info, space_info);
 256	if (ret)
 257		return ret;
 258
 259	list_add(&space_info->list, &info->space_info);
 260	if (flags & BTRFS_BLOCK_GROUP_DATA)
 261		info->data_sinfo = space_info;
 262
 263	return ret;
 264}
 265
 266int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
 267{
 268	struct btrfs_super_block *disk_super;
 269	u64 features;
 270	u64 flags;
 271	int mixed = 0;
 272	int ret;
 273
 274	disk_super = fs_info->super_copy;
 275	if (!btrfs_super_root(disk_super))
 276		return -EINVAL;
 277
 278	features = btrfs_super_incompat_flags(disk_super);
 279	if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
 280		mixed = 1;
 281
 282	flags = BTRFS_BLOCK_GROUP_SYSTEM;
 283	ret = create_space_info(fs_info, flags);
 284	if (ret)
 285		goto out;
 286
 287	if (mixed) {
 288		flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
 289		ret = create_space_info(fs_info, flags);
 290	} else {
 291		flags = BTRFS_BLOCK_GROUP_METADATA;
 292		ret = create_space_info(fs_info, flags);
 293		if (ret)
 294			goto out;
 295
 296		flags = BTRFS_BLOCK_GROUP_DATA;
 297		ret = create_space_info(fs_info, flags);
 298	}
 299out:
 300	return ret;
 301}
 302
 303void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
 304				struct btrfs_block_group *block_group)
 305{
 306	struct btrfs_space_info *found;
 307	int factor, index;
 308
 309	factor = btrfs_bg_type_to_factor(block_group->flags);
 310
 311	found = btrfs_find_space_info(info, block_group->flags);
 312	ASSERT(found);
 313	spin_lock(&found->lock);
 314	found->total_bytes += block_group->length;
 315	found->disk_total += block_group->length * factor;
 316	found->bytes_used += block_group->used;
 317	found->disk_used += block_group->used * factor;
 318	found->bytes_readonly += block_group->bytes_super;
 319	btrfs_space_info_update_bytes_zone_unusable(info, found, block_group->zone_unusable);
 320	if (block_group->length > 0)
 321		found->full = 0;
 322	btrfs_try_granting_tickets(info, found);
 323	spin_unlock(&found->lock);
 324
 325	block_group->space_info = found;
 326
 327	index = btrfs_bg_flags_to_raid_index(block_group->flags);
 328	down_write(&found->groups_sem);
 329	list_add_tail(&block_group->list, &found->block_groups[index]);
 330	up_write(&found->groups_sem);
 331}
 332
 333struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 334					       u64 flags)
 335{
 336	struct list_head *head = &info->space_info;
 337	struct btrfs_space_info *found;
 338
 339	flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
 340
 341	list_for_each_entry(found, head, list) {
 342		if (found->flags & flags)
 343			return found;
 344	}
 345	return NULL;
 346}
 347
 348static u64 calc_effective_data_chunk_size(struct btrfs_fs_info *fs_info)
 349{
 350	struct btrfs_space_info *data_sinfo;
 351	u64 data_chunk_size;
 352
 353	/*
 354	 * Calculate the data_chunk_size, space_info->chunk_size is the
 355	 * "optimal" chunk size based on the fs size.  However when we actually
 356	 * allocate the chunk we will strip this down further, making it no
 357	 * more than 10% of the disk or 1G, whichever is smaller.
 358	 *
 359	 * On the zoned mode, we need to use zone_size (= data_sinfo->chunk_size)
 360	 * as it is.
 361	 */
 362	data_sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA);
 363	if (btrfs_is_zoned(fs_info))
 364		return data_sinfo->chunk_size;
 365	data_chunk_size = min(data_sinfo->chunk_size,
 366			      mult_perc(fs_info->fs_devices->total_rw_bytes, 10));
 367	return min_t(u64, data_chunk_size, SZ_1G);
 368}
 369
 370static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
 371			  const struct btrfs_space_info *space_info,
 372			  enum btrfs_reserve_flush_enum flush)
 373{
 
 374	u64 profile;
 375	u64 avail;
 376	u64 data_chunk_size;
 377	int factor;
 378
 379	if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
 380		profile = btrfs_system_alloc_profile(fs_info);
 381	else
 382		profile = btrfs_metadata_alloc_profile(fs_info);
 383
 384	avail = atomic64_read(&fs_info->free_chunk_space);
 385
 386	/*
 387	 * If we have dup, raid1 or raid10 then only half of the free
 388	 * space is actually usable.  For raid56, the space info used
 389	 * doesn't include the parity drive, so we don't have to
 390	 * change the math
 391	 */
 392	factor = btrfs_bg_type_to_factor(profile);
 393	avail = div_u64(avail, factor);
 394	if (avail == 0)
 395		return 0;
 396
 397	data_chunk_size = calc_effective_data_chunk_size(fs_info);
 
 
 
 
 
 
 
 
 
 398
 399	/*
 400	 * Since data allocations immediately use block groups as part of the
 401	 * reservation, because we assume that data reservations will == actual
 402	 * usage, we could potentially overcommit and then immediately have that
 403	 * available space used by a data allocation, which could put us in a
 404	 * bind when we get close to filling the file system.
 405	 *
 406	 * To handle this simply remove the data_chunk_size from the available
 407	 * space.  If we are relatively empty this won't affect our ability to
 408	 * overcommit much, and if we're very close to full it'll keep us from
 409	 * getting into a position where we've given ourselves very little
 410	 * metadata wiggle room.
 411	 */
 412	if (avail <= data_chunk_size)
 413		return 0;
 414	avail -= data_chunk_size;
 415
 416	/*
 417	 * If we aren't flushing all things, let us overcommit up to
 418	 * 1/2th of the space. If we can flush, don't let us overcommit
 419	 * too much, let it overcommit up to 1/8 of the space.
 420	 */
 421	if (flush == BTRFS_RESERVE_FLUSH_ALL)
 422		avail >>= 3;
 423	else
 424		avail >>= 1;
 425
 426	/*
 427	 * On the zoned mode, we always allocate one zone as one chunk.
 428	 * Returning non-zone size alingned bytes here will result in
 429	 * less pressure for the async metadata reclaim process, and it
 430	 * will over-commit too much leading to ENOSPC. Align down to the
 431	 * zone size to avoid that.
 432	 */
 433	if (btrfs_is_zoned(fs_info))
 434		avail = ALIGN_DOWN(avail, fs_info->zone_size);
 435
 436	return avail;
 437}
 438
 439int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 440			 const struct btrfs_space_info *space_info, u64 bytes,
 441			 enum btrfs_reserve_flush_enum flush)
 442{
 443	u64 avail;
 444	u64 used;
 445
 446	/* Don't overcommit when in mixed mode */
 447	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
 448		return 0;
 449
 450	used = btrfs_space_info_used(space_info, true);
 451	avail = calc_available_free_space(fs_info, space_info, flush);
 452
 453	if (used + bytes < space_info->total_bytes + avail)
 454		return 1;
 455	return 0;
 456}
 457
 458static void remove_ticket(struct btrfs_space_info *space_info,
 459			  struct reserve_ticket *ticket)
 460{
 461	if (!list_empty(&ticket->list)) {
 462		list_del_init(&ticket->list);
 463		ASSERT(space_info->reclaim_size >= ticket->bytes);
 464		space_info->reclaim_size -= ticket->bytes;
 465	}
 466}
 467
 468/*
 469 * This is for space we already have accounted in space_info->bytes_may_use, so
 470 * basically when we're returning space from block_rsv's.
 471 */
 472void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
 473				struct btrfs_space_info *space_info)
 474{
 475	struct list_head *head;
 476	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
 477
 478	lockdep_assert_held(&space_info->lock);
 479
 480	head = &space_info->priority_tickets;
 481again:
 482	while (!list_empty(head)) {
 483		struct reserve_ticket *ticket;
 484		u64 used = btrfs_space_info_used(space_info, true);
 485
 486		ticket = list_first_entry(head, struct reserve_ticket, list);
 487
 488		/* Check and see if our ticket can be satisfied now. */
 489		if ((used + ticket->bytes <= space_info->total_bytes) ||
 490		    btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
 491					 flush)) {
 492			btrfs_space_info_update_bytes_may_use(fs_info,
 493							      space_info,
 494							      ticket->bytes);
 495			remove_ticket(space_info, ticket);
 496			ticket->bytes = 0;
 497			space_info->tickets_id++;
 498			wake_up(&ticket->wait);
 499		} else {
 500			break;
 501		}
 502	}
 503
 504	if (head == &space_info->priority_tickets) {
 505		head = &space_info->tickets;
 506		flush = BTRFS_RESERVE_FLUSH_ALL;
 507		goto again;
 508	}
 509}
 510
 511#define DUMP_BLOCK_RSV(fs_info, rsv_name)				\
 512do {									\
 513	struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name;		\
 514	spin_lock(&__rsv->lock);					\
 515	btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu",	\
 516		   __rsv->size, __rsv->reserved);			\
 517	spin_unlock(&__rsv->lock);					\
 518} while (0)
 519
 520static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info)
 521{
 522	switch (space_info->flags) {
 523	case BTRFS_BLOCK_GROUP_SYSTEM:
 524		return "SYSTEM";
 525	case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
 526		return "DATA+METADATA";
 527	case BTRFS_BLOCK_GROUP_DATA:
 528		return "DATA";
 529	case BTRFS_BLOCK_GROUP_METADATA:
 530		return "METADATA";
 531	default:
 532		return "UNKNOWN";
 533	}
 534}
 535
 536static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
 537{
 538	DUMP_BLOCK_RSV(fs_info, global_block_rsv);
 539	DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
 540	DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
 541	DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
 542	DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
 543}
 544
 545static void __btrfs_dump_space_info(const struct btrfs_fs_info *fs_info,
 546				    const struct btrfs_space_info *info)
 547{
 548	const char *flag_str = space_info_flag_to_str(info);
 549	lockdep_assert_held(&info->lock);
 550
 551	/* The free space could be negative in case of overcommit */
 552	btrfs_info(fs_info, "space_info %s has %lld free, is %sfull",
 553		   flag_str,
 554		   (s64)(info->total_bytes - btrfs_space_info_used(info, true)),
 555		   info->full ? "" : "not ");
 556	btrfs_info(fs_info,
 557"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
 558		info->total_bytes, info->bytes_used, info->bytes_pinned,
 559		info->bytes_reserved, info->bytes_may_use,
 560		info->bytes_readonly, info->bytes_zone_unusable);
 561}
 562
 563void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 564			   struct btrfs_space_info *info, u64 bytes,
 565			   int dump_block_groups)
 566{
 567	struct btrfs_block_group *cache;
 568	u64 total_avail = 0;
 569	int index = 0;
 570
 571	spin_lock(&info->lock);
 572	__btrfs_dump_space_info(fs_info, info);
 573	dump_global_block_rsv(fs_info);
 574	spin_unlock(&info->lock);
 575
 576	if (!dump_block_groups)
 577		return;
 578
 579	down_read(&info->groups_sem);
 580again:
 581	list_for_each_entry(cache, &info->block_groups[index], list) {
 582		u64 avail;
 583
 584		spin_lock(&cache->lock);
 585		avail = cache->length - cache->used - cache->pinned -
 586			cache->reserved - cache->bytes_super - cache->zone_unusable;
 
 587		btrfs_info(fs_info,
 588"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
 589			   cache->start, cache->length, cache->used, cache->pinned,
 590			   cache->reserved, cache->delalloc_bytes,
 591			   cache->bytes_super, cache->zone_unusable,
 592			   avail, cache->ro ? "[readonly]" : "");
 593		spin_unlock(&cache->lock);
 594		btrfs_dump_free_space(cache, bytes);
 595		total_avail += avail;
 596	}
 597	if (++index < BTRFS_NR_RAID_TYPES)
 598		goto again;
 599	up_read(&info->groups_sem);
 600
 601	btrfs_info(fs_info, "%llu bytes available across all block groups", total_avail);
 602}
 603
 604static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info,
 605					u64 to_reclaim)
 606{
 607	u64 bytes;
 608	u64 nr;
 609
 610	bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
 611	nr = div64_u64(to_reclaim, bytes);
 612	if (!nr)
 613		nr = 1;
 614	return nr;
 615}
 616
 
 
 617/*
 618 * shrink metadata reservation for delalloc
 619 */
 620static void shrink_delalloc(struct btrfs_fs_info *fs_info,
 621			    struct btrfs_space_info *space_info,
 622			    u64 to_reclaim, bool wait_ordered,
 623			    bool for_preempt)
 624{
 625	struct btrfs_trans_handle *trans;
 626	u64 delalloc_bytes;
 627	u64 ordered_bytes;
 628	u64 items;
 629	long time_left;
 630	int loops;
 631
 632	delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
 633	ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
 634	if (delalloc_bytes == 0 && ordered_bytes == 0)
 635		return;
 636
 637	/* Calc the number of the pages we need flush for space reservation */
 638	if (to_reclaim == U64_MAX) {
 639		items = U64_MAX;
 640	} else {
 641		/*
 642		 * to_reclaim is set to however much metadata we need to
 643		 * reclaim, but reclaiming that much data doesn't really track
 644		 * exactly.  What we really want to do is reclaim full inode's
 645		 * worth of reservations, however that's not available to us
 646		 * here.  We will take a fraction of the delalloc bytes for our
 647		 * flushing loops and hope for the best.  Delalloc will expand
 648		 * the amount we write to cover an entire dirty extent, which
 649		 * will reclaim the metadata reservation for that range.  If
 650		 * it's not enough subsequent flush stages will be more
 651		 * aggressive.
 652		 */
 653		to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
 654		items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
 655	}
 656
 657	trans = current->journal_info;
 658
 659	/*
 660	 * If we are doing more ordered than delalloc we need to just wait on
 661	 * ordered extents, otherwise we'll waste time trying to flush delalloc
 662	 * that likely won't give us the space back we need.
 663	 */
 664	if (ordered_bytes > delalloc_bytes && !for_preempt)
 665		wait_ordered = true;
 666
 667	loops = 0;
 668	while ((delalloc_bytes || ordered_bytes) && loops < 3) {
 669		u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
 670		long nr_pages = min_t(u64, temp, LONG_MAX);
 671		int async_pages;
 672
 673		btrfs_start_delalloc_roots(fs_info, nr_pages, true);
 674
 675		/*
 676		 * We need to make sure any outstanding async pages are now
 677		 * processed before we continue.  This is because things like
 678		 * sync_inode() try to be smart and skip writing if the inode is
 679		 * marked clean.  We don't use filemap_fwrite for flushing
 680		 * because we want to control how many pages we write out at a
 681		 * time, thus this is the only safe way to make sure we've
 682		 * waited for outstanding compressed workers to have started
 683		 * their jobs and thus have ordered extents set up properly.
 684		 *
 685		 * This exists because we do not want to wait for each
 686		 * individual inode to finish its async work, we simply want to
 687		 * start the IO on everybody, and then come back here and wait
 688		 * for all of the async work to catch up.  Once we're done with
 689		 * that we know we'll have ordered extents for everything and we
 690		 * can decide if we wait for that or not.
 691		 *
 692		 * If we choose to replace this in the future, make absolutely
 693		 * sure that the proper waiting is being done in the async case,
 694		 * as there have been bugs in that area before.
 695		 */
 696		async_pages = atomic_read(&fs_info->async_delalloc_pages);
 697		if (!async_pages)
 698			goto skip_async;
 699
 700		/*
 701		 * We don't want to wait forever, if we wrote less pages in this
 702		 * loop than we have outstanding, only wait for that number of
 703		 * pages, otherwise we can wait for all async pages to finish
 704		 * before continuing.
 705		 */
 706		if (async_pages > nr_pages)
 707			async_pages -= nr_pages;
 708		else
 709			async_pages = 0;
 710		wait_event(fs_info->async_submit_wait,
 711			   atomic_read(&fs_info->async_delalloc_pages) <=
 712			   async_pages);
 713skip_async:
 714		loops++;
 715		if (wait_ordered && !trans) {
 716			btrfs_wait_ordered_roots(fs_info, items, NULL);
 717		} else {
 718			time_left = schedule_timeout_killable(1);
 719			if (time_left)
 720				break;
 721		}
 722
 723		/*
 724		 * If we are for preemption we just want a one-shot of delalloc
 725		 * flushing so we can stop flushing if we decide we don't need
 726		 * to anymore.
 727		 */
 728		if (for_preempt)
 729			break;
 730
 731		spin_lock(&space_info->lock);
 732		if (list_empty(&space_info->tickets) &&
 733		    list_empty(&space_info->priority_tickets)) {
 734			spin_unlock(&space_info->lock);
 735			break;
 736		}
 737		spin_unlock(&space_info->lock);
 738
 739		delalloc_bytes = percpu_counter_sum_positive(
 740						&fs_info->delalloc_bytes);
 741		ordered_bytes = percpu_counter_sum_positive(
 742						&fs_info->ordered_bytes);
 743	}
 744}
 745
 746/*
 747 * Try to flush some data based on policy set by @state. This is only advisory
 748 * and may fail for various reasons. The caller is supposed to examine the
 749 * state of @space_info to detect the outcome.
 750 */
 751static void flush_space(struct btrfs_fs_info *fs_info,
 752		       struct btrfs_space_info *space_info, u64 num_bytes,
 753		       enum btrfs_flush_state state, bool for_preempt)
 754{
 755	struct btrfs_root *root = fs_info->tree_root;
 756	struct btrfs_trans_handle *trans;
 757	int nr;
 758	int ret = 0;
 759
 760	switch (state) {
 761	case FLUSH_DELAYED_ITEMS_NR:
 762	case FLUSH_DELAYED_ITEMS:
 763		if (state == FLUSH_DELAYED_ITEMS_NR)
 764			nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
 765		else
 766			nr = -1;
 767
 768		trans = btrfs_join_transaction_nostart(root);
 769		if (IS_ERR(trans)) {
 770			ret = PTR_ERR(trans);
 771			if (ret == -ENOENT)
 772				ret = 0;
 773			break;
 774		}
 775		ret = btrfs_run_delayed_items_nr(trans, nr);
 776		btrfs_end_transaction(trans);
 777		break;
 778	case FLUSH_DELALLOC:
 779	case FLUSH_DELALLOC_WAIT:
 780	case FLUSH_DELALLOC_FULL:
 781		if (state == FLUSH_DELALLOC_FULL)
 782			num_bytes = U64_MAX;
 783		shrink_delalloc(fs_info, space_info, num_bytes,
 784				state != FLUSH_DELALLOC, for_preempt);
 785		break;
 786	case FLUSH_DELAYED_REFS_NR:
 787	case FLUSH_DELAYED_REFS:
 788		trans = btrfs_join_transaction_nostart(root);
 789		if (IS_ERR(trans)) {
 790			ret = PTR_ERR(trans);
 791			if (ret == -ENOENT)
 792				ret = 0;
 793			break;
 794		}
 795		if (state == FLUSH_DELAYED_REFS_NR)
 796			btrfs_run_delayed_refs(trans, num_bytes);
 797		else
 798			btrfs_run_delayed_refs(trans, 0);
 799		btrfs_end_transaction(trans);
 800		break;
 801	case ALLOC_CHUNK:
 802	case ALLOC_CHUNK_FORCE:
 803		trans = btrfs_join_transaction(root);
 804		if (IS_ERR(trans)) {
 805			ret = PTR_ERR(trans);
 806			break;
 807		}
 808		ret = btrfs_chunk_alloc(trans,
 809				btrfs_get_alloc_profile(fs_info, space_info->flags),
 810				(state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
 811					CHUNK_ALLOC_FORCE);
 812		btrfs_end_transaction(trans);
 813
 814		if (ret > 0 || ret == -ENOSPC)
 815			ret = 0;
 816		break;
 817	case RUN_DELAYED_IPUTS:
 818		/*
 819		 * If we have pending delayed iputs then we could free up a
 820		 * bunch of pinned space, so make sure we run the iputs before
 821		 * we do our pinned bytes check below.
 822		 */
 823		btrfs_run_delayed_iputs(fs_info);
 824		btrfs_wait_on_delayed_iputs(fs_info);
 825		break;
 826	case COMMIT_TRANS:
 827		ASSERT(current->journal_info == NULL);
 828		/*
 829		 * We don't want to start a new transaction, just attach to the
 830		 * current one or wait it fully commits in case its commit is
 831		 * happening at the moment. Note: we don't use a nostart join
 832		 * because that does not wait for a transaction to fully commit
 833		 * (only for it to be unblocked, state TRANS_STATE_UNBLOCKED).
 834		 */
 835		ret = btrfs_commit_current_transaction(root);
 
 
 
 
 
 
 
 836		break;
 837	default:
 838		ret = -ENOSPC;
 839		break;
 840	}
 841
 842	trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
 843				ret, for_preempt);
 844	return;
 845}
 846
 847static u64 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 848					    const struct btrfs_space_info *space_info)
 
 849{
 850	u64 used;
 851	u64 avail;
 852	u64 to_reclaim = space_info->reclaim_size;
 853
 854	lockdep_assert_held(&space_info->lock);
 855
 856	avail = calc_available_free_space(fs_info, space_info,
 857					  BTRFS_RESERVE_FLUSH_ALL);
 858	used = btrfs_space_info_used(space_info, true);
 859
 860	/*
 861	 * We may be flushing because suddenly we have less space than we had
 862	 * before, and now we're well over-committed based on our current free
 863	 * space.  If that's the case add in our overage so we make sure to put
 864	 * appropriate pressure on the flushing state machine.
 865	 */
 866	if (space_info->total_bytes + avail < used)
 867		to_reclaim += used - (space_info->total_bytes + avail);
 868
 869	return to_reclaim;
 870}
 871
 872static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 873				    const struct btrfs_space_info *space_info)
 874{
 875	const u64 global_rsv_size = btrfs_block_rsv_reserved(&fs_info->global_block_rsv);
 876	u64 ordered, delalloc;
 877	u64 thresh;
 878	u64 used;
 879
 880	thresh = mult_perc(space_info->total_bytes, 90);
 881
 882	lockdep_assert_held(&space_info->lock);
 883
 884	/* If we're just plain full then async reclaim just slows us down. */
 885	if ((space_info->bytes_used + space_info->bytes_reserved +
 886	     global_rsv_size) >= thresh)
 887		return false;
 888
 889	used = space_info->bytes_may_use + space_info->bytes_pinned;
 890
 891	/* The total flushable belongs to the global rsv, don't flush. */
 892	if (global_rsv_size >= used)
 893		return false;
 894
 895	/*
 896	 * 128MiB is 1/4 of the maximum global rsv size.  If we have less than
 897	 * that devoted to other reservations then there's no sense in flushing,
 898	 * we don't have a lot of things that need flushing.
 899	 */
 900	if (used - global_rsv_size <= SZ_128M)
 901		return false;
 902
 903	/*
 904	 * We have tickets queued, bail so we don't compete with the async
 905	 * flushers.
 906	 */
 907	if (space_info->reclaim_size)
 908		return false;
 909
 910	/*
 911	 * If we have over half of the free space occupied by reservations or
 912	 * pinned then we want to start flushing.
 913	 *
 914	 * We do not do the traditional thing here, which is to say
 915	 *
 916	 *   if (used >= ((total_bytes + avail) / 2))
 917	 *     return 1;
 918	 *
 919	 * because this doesn't quite work how we want.  If we had more than 50%
 920	 * of the space_info used by bytes_used and we had 0 available we'd just
 921	 * constantly run the background flusher.  Instead we want it to kick in
 922	 * if our reclaimable space exceeds our clamped free space.
 923	 *
 924	 * Our clamping range is 2^1 -> 2^8.  Practically speaking that means
 925	 * the following:
 926	 *
 927	 * Amount of RAM        Minimum threshold       Maximum threshold
 928	 *
 929	 *        256GiB                     1GiB                  128GiB
 930	 *        128GiB                   512MiB                   64GiB
 931	 *         64GiB                   256MiB                   32GiB
 932	 *         32GiB                   128MiB                   16GiB
 933	 *         16GiB                    64MiB                    8GiB
 934	 *
 935	 * These are the range our thresholds will fall in, corresponding to how
 936	 * much delalloc we need for the background flusher to kick in.
 937	 */
 938
 939	thresh = calc_available_free_space(fs_info, space_info,
 940					   BTRFS_RESERVE_FLUSH_ALL);
 941	used = space_info->bytes_used + space_info->bytes_reserved +
 942	       space_info->bytes_readonly + global_rsv_size;
 943	if (used < space_info->total_bytes)
 944		thresh += space_info->total_bytes - used;
 945	thresh >>= space_info->clamp;
 946
 947	used = space_info->bytes_pinned;
 948
 949	/*
 950	 * If we have more ordered bytes than delalloc bytes then we're either
 951	 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
 952	 * around.  Preemptive flushing is only useful in that it can free up
 953	 * space before tickets need to wait for things to finish.  In the case
 954	 * of ordered extents, preemptively waiting on ordered extents gets us
 955	 * nothing, if our reservations are tied up in ordered extents we'll
 956	 * simply have to slow down writers by forcing them to wait on ordered
 957	 * extents.
 958	 *
 959	 * In the case that ordered is larger than delalloc, only include the
 960	 * block reserves that we would actually be able to directly reclaim
 961	 * from.  In this case if we're heavy on metadata operations this will
 962	 * clearly be heavy enough to warrant preemptive flushing.  In the case
 963	 * of heavy DIO or ordered reservations, preemptive flushing will just
 964	 * waste time and cause us to slow down.
 965	 *
 966	 * We want to make sure we truly are maxed out on ordered however, so
 967	 * cut ordered in half, and if it's still higher than delalloc then we
 968	 * can keep flushing.  This is to avoid the case where we start
 969	 * flushing, and now delalloc == ordered and we stop preemptively
 970	 * flushing when we could still have several gigs of delalloc to flush.
 971	 */
 972	ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
 973	delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
 974	if (ordered >= delalloc)
 975		used += btrfs_block_rsv_reserved(&fs_info->delayed_refs_rsv) +
 976			btrfs_block_rsv_reserved(&fs_info->delayed_block_rsv);
 977	else
 978		used += space_info->bytes_may_use - global_rsv_size;
 979
 980	return (used >= thresh && !btrfs_fs_closing(fs_info) &&
 981		!test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
 982}
 983
 984static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
 985				  struct btrfs_space_info *space_info,
 986				  struct reserve_ticket *ticket)
 987{
 988	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
 989	u64 min_bytes;
 990
 991	if (!ticket->steal)
 992		return false;
 993
 994	if (global_rsv->space_info != space_info)
 995		return false;
 996
 997	spin_lock(&global_rsv->lock);
 998	min_bytes = mult_perc(global_rsv->size, 10);
 999	if (global_rsv->reserved < min_bytes + ticket->bytes) {
1000		spin_unlock(&global_rsv->lock);
1001		return false;
1002	}
1003	global_rsv->reserved -= ticket->bytes;
1004	remove_ticket(space_info, ticket);
1005	ticket->bytes = 0;
1006	wake_up(&ticket->wait);
1007	space_info->tickets_id++;
1008	if (global_rsv->reserved < global_rsv->size)
1009		global_rsv->full = 0;
1010	spin_unlock(&global_rsv->lock);
1011
1012	return true;
1013}
1014
1015/*
1016 * We've exhausted our flushing, start failing tickets.
1017 *
1018 * @fs_info - fs_info for this fs
1019 * @space_info - the space info we were flushing
1020 *
1021 * We call this when we've exhausted our flushing ability and haven't made
1022 * progress in satisfying tickets.  The reservation code handles tickets in
1023 * order, so if there is a large ticket first and then smaller ones we could
1024 * very well satisfy the smaller tickets.  This will attempt to wake up any
1025 * tickets in the list to catch this case.
1026 *
1027 * This function returns true if it was able to make progress by clearing out
1028 * other tickets, or if it stumbles across a ticket that was smaller than the
1029 * first ticket.
1030 */
1031static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
1032				   struct btrfs_space_info *space_info)
1033{
1034	struct reserve_ticket *ticket;
1035	u64 tickets_id = space_info->tickets_id;
1036	const bool aborted = BTRFS_FS_ERROR(fs_info);
1037
1038	trace_btrfs_fail_all_tickets(fs_info, space_info);
1039
1040	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
1041		btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
1042		__btrfs_dump_space_info(fs_info, space_info);
1043	}
1044
1045	while (!list_empty(&space_info->tickets) &&
1046	       tickets_id == space_info->tickets_id) {
1047		ticket = list_first_entry(&space_info->tickets,
1048					  struct reserve_ticket, list);
1049
1050		if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket))
1051			return true;
1052
1053		if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1054			btrfs_info(fs_info, "failing ticket with %llu bytes",
1055				   ticket->bytes);
1056
1057		remove_ticket(space_info, ticket);
1058		if (aborted)
1059			ticket->error = -EIO;
1060		else
1061			ticket->error = -ENOSPC;
1062		wake_up(&ticket->wait);
1063
1064		/*
1065		 * We're just throwing tickets away, so more flushing may not
1066		 * trip over btrfs_try_granting_tickets, so we need to call it
1067		 * here to see if we can make progress with the next ticket in
1068		 * the list.
1069		 */
1070		if (!aborted)
1071			btrfs_try_granting_tickets(fs_info, space_info);
1072	}
1073	return (tickets_id != space_info->tickets_id);
1074}
1075
1076/*
1077 * This is for normal flushers, we can wait all goddamned day if we want to.  We
1078 * will loop and continuously try to flush as long as we are making progress.
1079 * We count progress as clearing off tickets each time we have to loop.
1080 */
1081static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
1082{
1083	struct btrfs_fs_info *fs_info;
1084	struct btrfs_space_info *space_info;
1085	u64 to_reclaim;
1086	enum btrfs_flush_state flush_state;
1087	int commit_cycles = 0;
1088	u64 last_tickets_id;
1089
1090	fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
1091	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1092
1093	spin_lock(&space_info->lock);
1094	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1095	if (!to_reclaim) {
1096		space_info->flush = 0;
1097		spin_unlock(&space_info->lock);
1098		return;
1099	}
1100	last_tickets_id = space_info->tickets_id;
1101	spin_unlock(&space_info->lock);
1102
1103	flush_state = FLUSH_DELAYED_ITEMS_NR;
1104	do {
1105		flush_space(fs_info, space_info, to_reclaim, flush_state, false);
1106		spin_lock(&space_info->lock);
1107		if (list_empty(&space_info->tickets)) {
1108			space_info->flush = 0;
1109			spin_unlock(&space_info->lock);
1110			return;
1111		}
1112		to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1113							      space_info);
1114		if (last_tickets_id == space_info->tickets_id) {
1115			flush_state++;
1116		} else {
1117			last_tickets_id = space_info->tickets_id;
1118			flush_state = FLUSH_DELAYED_ITEMS_NR;
1119			if (commit_cycles)
1120				commit_cycles--;
1121		}
1122
1123		/*
1124		 * We do not want to empty the system of delalloc unless we're
1125		 * under heavy pressure, so allow one trip through the flushing
1126		 * logic before we start doing a FLUSH_DELALLOC_FULL.
1127		 */
1128		if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
1129			flush_state++;
1130
1131		/*
1132		 * We don't want to force a chunk allocation until we've tried
1133		 * pretty hard to reclaim space.  Think of the case where we
1134		 * freed up a bunch of space and so have a lot of pinned space
1135		 * to reclaim.  We would rather use that than possibly create a
1136		 * underutilized metadata chunk.  So if this is our first run
1137		 * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1138		 * commit the transaction.  If nothing has changed the next go
1139		 * around then we can force a chunk allocation.
1140		 */
1141		if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1142			flush_state++;
1143
1144		if (flush_state > COMMIT_TRANS) {
1145			commit_cycles++;
1146			if (commit_cycles > 2) {
1147				if (maybe_fail_all_tickets(fs_info, space_info)) {
1148					flush_state = FLUSH_DELAYED_ITEMS_NR;
1149					commit_cycles--;
1150				} else {
1151					space_info->flush = 0;
1152				}
1153			} else {
1154				flush_state = FLUSH_DELAYED_ITEMS_NR;
1155			}
1156		}
1157		spin_unlock(&space_info->lock);
1158	} while (flush_state <= COMMIT_TRANS);
1159}
1160
1161/*
1162 * This handles pre-flushing of metadata space before we get to the point that
1163 * we need to start blocking threads on tickets.  The logic here is different
1164 * from the other flush paths because it doesn't rely on tickets to tell us how
1165 * much we need to flush, instead it attempts to keep us below the 80% full
1166 * watermark of space by flushing whichever reservation pool is currently the
1167 * largest.
1168 */
1169static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
1170{
1171	struct btrfs_fs_info *fs_info;
1172	struct btrfs_space_info *space_info;
1173	struct btrfs_block_rsv *delayed_block_rsv;
1174	struct btrfs_block_rsv *delayed_refs_rsv;
1175	struct btrfs_block_rsv *global_rsv;
1176	struct btrfs_block_rsv *trans_rsv;
1177	int loops = 0;
1178
1179	fs_info = container_of(work, struct btrfs_fs_info,
1180			       preempt_reclaim_work);
1181	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
1182	delayed_block_rsv = &fs_info->delayed_block_rsv;
1183	delayed_refs_rsv = &fs_info->delayed_refs_rsv;
1184	global_rsv = &fs_info->global_block_rsv;
1185	trans_rsv = &fs_info->trans_block_rsv;
1186
1187	spin_lock(&space_info->lock);
1188	while (need_preemptive_reclaim(fs_info, space_info)) {
1189		enum btrfs_flush_state flush;
1190		u64 delalloc_size = 0;
1191		u64 to_reclaim, block_rsv_size;
1192		const u64 global_rsv_size = btrfs_block_rsv_reserved(global_rsv);
1193
1194		loops++;
1195
1196		/*
1197		 * We don't have a precise counter for the metadata being
1198		 * reserved for delalloc, so we'll approximate it by subtracting
1199		 * out the block rsv's space from the bytes_may_use.  If that
1200		 * amount is higher than the individual reserves, then we can
1201		 * assume it's tied up in delalloc reservations.
1202		 */
1203		block_rsv_size = global_rsv_size +
1204			btrfs_block_rsv_reserved(delayed_block_rsv) +
1205			btrfs_block_rsv_reserved(delayed_refs_rsv) +
1206			btrfs_block_rsv_reserved(trans_rsv);
1207		if (block_rsv_size < space_info->bytes_may_use)
1208			delalloc_size = space_info->bytes_may_use - block_rsv_size;
1209
1210		/*
1211		 * We don't want to include the global_rsv in our calculation,
1212		 * because that's space we can't touch.  Subtract it from the
1213		 * block_rsv_size for the next checks.
1214		 */
1215		block_rsv_size -= global_rsv_size;
1216
1217		/*
1218		 * We really want to avoid flushing delalloc too much, as it
1219		 * could result in poor allocation patterns, so only flush it if
1220		 * it's larger than the rest of the pools combined.
1221		 */
1222		if (delalloc_size > block_rsv_size) {
1223			to_reclaim = delalloc_size;
1224			flush = FLUSH_DELALLOC;
1225		} else if (space_info->bytes_pinned >
1226			   (btrfs_block_rsv_reserved(delayed_block_rsv) +
1227			    btrfs_block_rsv_reserved(delayed_refs_rsv))) {
1228			to_reclaim = space_info->bytes_pinned;
1229			flush = COMMIT_TRANS;
1230		} else if (btrfs_block_rsv_reserved(delayed_block_rsv) >
1231			   btrfs_block_rsv_reserved(delayed_refs_rsv)) {
1232			to_reclaim = btrfs_block_rsv_reserved(delayed_block_rsv);
1233			flush = FLUSH_DELAYED_ITEMS_NR;
1234		} else {
1235			to_reclaim = btrfs_block_rsv_reserved(delayed_refs_rsv);
1236			flush = FLUSH_DELAYED_REFS_NR;
1237		}
1238
1239		spin_unlock(&space_info->lock);
1240
1241		/*
1242		 * We don't want to reclaim everything, just a portion, so scale
1243		 * down the to_reclaim by 1/4.  If it takes us down to 0,
1244		 * reclaim 1 items worth.
1245		 */
1246		to_reclaim >>= 2;
1247		if (!to_reclaim)
1248			to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
1249		flush_space(fs_info, space_info, to_reclaim, flush, true);
1250		cond_resched();
1251		spin_lock(&space_info->lock);
1252	}
1253
1254	/* We only went through once, back off our clamping. */
1255	if (loops == 1 && !space_info->reclaim_size)
1256		space_info->clamp = max(1, space_info->clamp - 1);
1257	trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
1258	spin_unlock(&space_info->lock);
1259}
1260
1261/*
1262 * FLUSH_DELALLOC_WAIT:
1263 *   Space is freed from flushing delalloc in one of two ways.
1264 *
1265 *   1) compression is on and we allocate less space than we reserved
1266 *   2) we are overwriting existing space
1267 *
1268 *   For #1 that extra space is reclaimed as soon as the delalloc pages are
1269 *   COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
1270 *   length to ->bytes_reserved, and subtracts the reserved space from
1271 *   ->bytes_may_use.
1272 *
1273 *   For #2 this is trickier.  Once the ordered extent runs we will drop the
1274 *   extent in the range we are overwriting, which creates a delayed ref for
1275 *   that freed extent.  This however is not reclaimed until the transaction
1276 *   commits, thus the next stages.
1277 *
1278 * RUN_DELAYED_IPUTS
1279 *   If we are freeing inodes, we want to make sure all delayed iputs have
1280 *   completed, because they could have been on an inode with i_nlink == 0, and
1281 *   thus have been truncated and freed up space.  But again this space is not
1282 *   immediately reusable, it comes in the form of a delayed ref, which must be
1283 *   run and then the transaction must be committed.
1284 *
1285 * COMMIT_TRANS
1286 *   This is where we reclaim all of the pinned space generated by running the
1287 *   iputs
1288 *
1289 * ALLOC_CHUNK_FORCE
1290 *   For data we start with alloc chunk force, however we could have been full
1291 *   before, and then the transaction commit could have freed new block groups,
1292 *   so if we now have space to allocate do the force chunk allocation.
1293 */
1294static const enum btrfs_flush_state data_flush_states[] = {
1295	FLUSH_DELALLOC_FULL,
1296	RUN_DELAYED_IPUTS,
1297	COMMIT_TRANS,
1298	ALLOC_CHUNK_FORCE,
1299};
1300
1301static void btrfs_async_reclaim_data_space(struct work_struct *work)
1302{
1303	struct btrfs_fs_info *fs_info;
1304	struct btrfs_space_info *space_info;
1305	u64 last_tickets_id;
1306	enum btrfs_flush_state flush_state = 0;
1307
1308	fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
1309	space_info = fs_info->data_sinfo;
1310
1311	spin_lock(&space_info->lock);
1312	if (list_empty(&space_info->tickets)) {
1313		space_info->flush = 0;
1314		spin_unlock(&space_info->lock);
1315		return;
1316	}
1317	last_tickets_id = space_info->tickets_id;
1318	spin_unlock(&space_info->lock);
1319
1320	while (!space_info->full) {
1321		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1322		spin_lock(&space_info->lock);
1323		if (list_empty(&space_info->tickets)) {
1324			space_info->flush = 0;
1325			spin_unlock(&space_info->lock);
1326			return;
1327		}
1328
1329		/* Something happened, fail everything and bail. */
1330		if (BTRFS_FS_ERROR(fs_info))
1331			goto aborted_fs;
1332		last_tickets_id = space_info->tickets_id;
1333		spin_unlock(&space_info->lock);
1334	}
1335
1336	while (flush_state < ARRAY_SIZE(data_flush_states)) {
1337		flush_space(fs_info, space_info, U64_MAX,
1338			    data_flush_states[flush_state], false);
1339		spin_lock(&space_info->lock);
1340		if (list_empty(&space_info->tickets)) {
1341			space_info->flush = 0;
1342			spin_unlock(&space_info->lock);
1343			return;
1344		}
1345
1346		if (last_tickets_id == space_info->tickets_id) {
1347			flush_state++;
1348		} else {
1349			last_tickets_id = space_info->tickets_id;
1350			flush_state = 0;
1351		}
1352
1353		if (flush_state >= ARRAY_SIZE(data_flush_states)) {
1354			if (space_info->full) {
1355				if (maybe_fail_all_tickets(fs_info, space_info))
1356					flush_state = 0;
1357				else
1358					space_info->flush = 0;
1359			} else {
1360				flush_state = 0;
1361			}
1362
1363			/* Something happened, fail everything and bail. */
1364			if (BTRFS_FS_ERROR(fs_info))
1365				goto aborted_fs;
1366
1367		}
1368		spin_unlock(&space_info->lock);
1369	}
1370	return;
1371
1372aborted_fs:
1373	maybe_fail_all_tickets(fs_info, space_info);
1374	space_info->flush = 0;
1375	spin_unlock(&space_info->lock);
1376}
1377
1378void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
1379{
1380	INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
1381	INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
1382	INIT_WORK(&fs_info->preempt_reclaim_work,
1383		  btrfs_preempt_reclaim_metadata_space);
1384}
1385
1386static const enum btrfs_flush_state priority_flush_states[] = {
1387	FLUSH_DELAYED_ITEMS_NR,
1388	FLUSH_DELAYED_ITEMS,
1389	ALLOC_CHUNK,
1390};
1391
1392static const enum btrfs_flush_state evict_flush_states[] = {
1393	FLUSH_DELAYED_ITEMS_NR,
1394	FLUSH_DELAYED_ITEMS,
1395	FLUSH_DELAYED_REFS_NR,
1396	FLUSH_DELAYED_REFS,
1397	FLUSH_DELALLOC,
1398	FLUSH_DELALLOC_WAIT,
1399	FLUSH_DELALLOC_FULL,
1400	ALLOC_CHUNK,
1401	COMMIT_TRANS,
1402};
1403
1404static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1405				struct btrfs_space_info *space_info,
1406				struct reserve_ticket *ticket,
1407				const enum btrfs_flush_state *states,
1408				int states_nr)
1409{
1410	u64 to_reclaim;
1411	int flush_state = 0;
1412
1413	spin_lock(&space_info->lock);
1414	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1415	/*
1416	 * This is the priority reclaim path, so to_reclaim could be >0 still
1417	 * because we may have only satisfied the priority tickets and still
1418	 * left non priority tickets on the list.  We would then have
1419	 * to_reclaim but ->bytes == 0.
1420	 */
1421	if (ticket->bytes == 0) {
1422		spin_unlock(&space_info->lock);
1423		return;
1424	}
1425
1426	while (flush_state < states_nr) {
1427		spin_unlock(&space_info->lock);
1428		flush_space(fs_info, space_info, to_reclaim, states[flush_state],
1429			    false);
1430		flush_state++;
1431		spin_lock(&space_info->lock);
1432		if (ticket->bytes == 0) {
1433			spin_unlock(&space_info->lock);
1434			return;
1435		}
1436	}
1437
1438	/*
1439	 * Attempt to steal from the global rsv if we can, except if the fs was
1440	 * turned into error mode due to a transaction abort when flushing space
1441	 * above, in that case fail with the abort error instead of returning
1442	 * success to the caller if we can steal from the global rsv - this is
1443	 * just to have caller fail immeditelly instead of later when trying to
1444	 * modify the fs, making it easier to debug -ENOSPC problems.
1445	 */
1446	if (BTRFS_FS_ERROR(fs_info)) {
1447		ticket->error = BTRFS_FS_ERROR(fs_info);
1448		remove_ticket(space_info, ticket);
1449	} else if (!steal_from_global_rsv(fs_info, space_info, ticket)) {
1450		ticket->error = -ENOSPC;
1451		remove_ticket(space_info, ticket);
1452	}
1453
1454	/*
1455	 * We must run try_granting_tickets here because we could be a large
1456	 * ticket in front of a smaller ticket that can now be satisfied with
1457	 * the available space.
1458	 */
1459	btrfs_try_granting_tickets(fs_info, space_info);
1460	spin_unlock(&space_info->lock);
1461}
1462
1463static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
1464					struct btrfs_space_info *space_info,
1465					struct reserve_ticket *ticket)
1466{
1467	spin_lock(&space_info->lock);
1468
1469	/* We could have been granted before we got here. */
1470	if (ticket->bytes == 0) {
1471		spin_unlock(&space_info->lock);
1472		return;
1473	}
1474
1475	while (!space_info->full) {
1476		spin_unlock(&space_info->lock);
1477		flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
1478		spin_lock(&space_info->lock);
1479		if (ticket->bytes == 0) {
1480			spin_unlock(&space_info->lock);
1481			return;
1482		}
1483	}
1484
1485	ticket->error = -ENOSPC;
1486	remove_ticket(space_info, ticket);
1487	btrfs_try_granting_tickets(fs_info, space_info);
1488	spin_unlock(&space_info->lock);
1489}
1490
1491static void wait_reserve_ticket(struct btrfs_space_info *space_info,
 
1492				struct reserve_ticket *ticket)
1493
1494{
1495	DEFINE_WAIT(wait);
1496	int ret = 0;
1497
1498	spin_lock(&space_info->lock);
1499	while (ticket->bytes > 0 && ticket->error == 0) {
1500		ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1501		if (ret) {
1502			/*
1503			 * Delete us from the list. After we unlock the space
1504			 * info, we don't want the async reclaim job to reserve
1505			 * space for this ticket. If that would happen, then the
1506			 * ticket's task would not known that space was reserved
1507			 * despite getting an error, resulting in a space leak
1508			 * (bytes_may_use counter of our space_info).
1509			 */
1510			remove_ticket(space_info, ticket);
1511			ticket->error = -EINTR;
1512			break;
1513		}
1514		spin_unlock(&space_info->lock);
1515
1516		schedule();
1517
1518		finish_wait(&ticket->wait, &wait);
1519		spin_lock(&space_info->lock);
1520	}
1521	spin_unlock(&space_info->lock);
1522}
1523
1524/*
1525 * Do the appropriate flushing and waiting for a ticket.
1526 *
1527 * @fs_info:    the filesystem
1528 * @space_info: space info for the reservation
1529 * @ticket:     ticket for the reservation
1530 * @start_ns:   timestamp when the reservation started
1531 * @orig_bytes: amount of bytes originally reserved
1532 * @flush:      how much we can flush
1533 *
1534 * This does the work of figuring out how to flush for the ticket, waiting for
1535 * the reservation, and returning the appropriate error if there is one.
1536 */
1537static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1538				 struct btrfs_space_info *space_info,
1539				 struct reserve_ticket *ticket,
1540				 u64 start_ns, u64 orig_bytes,
1541				 enum btrfs_reserve_flush_enum flush)
1542{
1543	int ret;
1544
1545	switch (flush) {
1546	case BTRFS_RESERVE_FLUSH_DATA:
1547	case BTRFS_RESERVE_FLUSH_ALL:
1548	case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1549		wait_reserve_ticket(space_info, ticket);
1550		break;
1551	case BTRFS_RESERVE_FLUSH_LIMIT:
1552		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1553						priority_flush_states,
1554						ARRAY_SIZE(priority_flush_states));
1555		break;
1556	case BTRFS_RESERVE_FLUSH_EVICT:
1557		priority_reclaim_metadata_space(fs_info, space_info, ticket,
1558						evict_flush_states,
1559						ARRAY_SIZE(evict_flush_states));
1560		break;
1561	case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
1562		priority_reclaim_data_space(fs_info, space_info, ticket);
1563		break;
1564	default:
1565		ASSERT(0);
1566		break;
1567	}
1568
1569	ret = ticket->error;
1570	ASSERT(list_empty(&ticket->list));
1571	/*
1572	 * Check that we can't have an error set if the reservation succeeded,
1573	 * as that would confuse tasks and lead them to error out without
1574	 * releasing reserved space (if an error happens the expectation is that
1575	 * space wasn't reserved at all).
1576	 */
1577	ASSERT(!(ticket->bytes == 0 && ticket->error));
1578	trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
1579				   start_ns, flush, ticket->error);
1580	return ret;
1581}
1582
1583/*
1584 * This returns true if this flush state will go through the ordinary flushing
1585 * code.
1586 */
1587static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
1588{
1589	return	(flush == BTRFS_RESERVE_FLUSH_ALL) ||
1590		(flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1591}
1592
1593static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
1594				       struct btrfs_space_info *space_info)
1595{
1596	u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
1597	u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1598
1599	/*
1600	 * If we're heavy on ordered operations then clamping won't help us.  We
1601	 * need to clamp specifically to keep up with dirty'ing buffered
1602	 * writers, because there's not a 1:1 correlation of writing delalloc
1603	 * and freeing space, like there is with flushing delayed refs or
1604	 * delayed nodes.  If we're already more ordered than delalloc then
1605	 * we're keeping up, otherwise we aren't and should probably clamp.
1606	 */
1607	if (ordered < delalloc)
1608		space_info->clamp = min(space_info->clamp + 1, 8);
1609}
1610
1611static inline bool can_steal(enum btrfs_reserve_flush_enum flush)
1612{
1613	return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1614		flush == BTRFS_RESERVE_FLUSH_EVICT);
1615}
1616
1617/*
1618 * NO_FLUSH and FLUSH_EMERGENCY don't want to create a ticket, they just want to
1619 * fail as quickly as possible.
1620 */
1621static inline bool can_ticket(enum btrfs_reserve_flush_enum flush)
1622{
1623	return (flush != BTRFS_RESERVE_NO_FLUSH &&
1624		flush != BTRFS_RESERVE_FLUSH_EMERGENCY);
1625}
1626
1627/*
1628 * Try to reserve bytes from the block_rsv's space.
1629 *
1630 * @fs_info:    the filesystem
1631 * @space_info: space info we want to allocate from
1632 * @orig_bytes: number of bytes we want
1633 * @flush:      whether or not we can flush to make our reservation
1634 *
1635 * This will reserve orig_bytes number of bytes from the space info associated
1636 * with the block_rsv.  If there is not enough space it will make an attempt to
1637 * flush out space to make room.  It will do this by flushing delalloc if
1638 * possible or committing the transaction.  If flush is 0 then no attempts to
1639 * regain reservations will be made and this will fail if there is not enough
1640 * space already.
1641 */
1642static int __reserve_bytes(struct btrfs_fs_info *fs_info,
1643			   struct btrfs_space_info *space_info, u64 orig_bytes,
1644			   enum btrfs_reserve_flush_enum flush)
1645{
1646	struct work_struct *async_work;
1647	struct reserve_ticket ticket;
1648	u64 start_ns = 0;
1649	u64 used;
1650	int ret = -ENOSPC;
1651	bool pending_tickets;
1652
1653	ASSERT(orig_bytes);
1654	/*
1655	 * If have a transaction handle (current->journal_info != NULL), then
1656	 * the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor
1657	 * BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those
1658	 * flushing methods can trigger transaction commits.
1659	 */
1660	if (current->journal_info) {
1661		/* One assert per line for easier debugging. */
1662		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL);
1663		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL);
1664		ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT);
1665	}
1666
1667	if (flush == BTRFS_RESERVE_FLUSH_DATA)
1668		async_work = &fs_info->async_data_reclaim_work;
1669	else
1670		async_work = &fs_info->async_reclaim_work;
1671
1672	spin_lock(&space_info->lock);
1673	used = btrfs_space_info_used(space_info, true);
1674
1675	/*
1676	 * We don't want NO_FLUSH allocations to jump everybody, they can
1677	 * generally handle ENOSPC in a different way, so treat them the same as
1678	 * normal flushers when it comes to skipping pending tickets.
1679	 */
1680	if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
1681		pending_tickets = !list_empty(&space_info->tickets) ||
1682			!list_empty(&space_info->priority_tickets);
1683	else
1684		pending_tickets = !list_empty(&space_info->priority_tickets);
1685
1686	/*
1687	 * Carry on if we have enough space (short-circuit) OR call
1688	 * can_overcommit() to ensure we can overcommit to continue.
1689	 */
1690	if (!pending_tickets &&
1691	    ((used + orig_bytes <= space_info->total_bytes) ||
1692	     btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1693		btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1694						      orig_bytes);
1695		ret = 0;
1696	}
1697
1698	/*
1699	 * Things are dire, we need to make a reservation so we don't abort.  We
1700	 * will let this reservation go through as long as we have actual space
1701	 * left to allocate for the block.
1702	 */
1703	if (ret && unlikely(flush == BTRFS_RESERVE_FLUSH_EMERGENCY)) {
1704		used = btrfs_space_info_used(space_info, false);
1705		if (used + orig_bytes <= space_info->total_bytes) {
1706			btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1707							      orig_bytes);
1708			ret = 0;
1709		}
1710	}
1711
1712	/*
1713	 * If we couldn't make a reservation then setup our reservation ticket
1714	 * and kick the async worker if it's not already running.
1715	 *
1716	 * If we are a priority flusher then we just need to add our ticket to
1717	 * the list and we will do our own flushing further down.
1718	 */
1719	if (ret && can_ticket(flush)) {
1720		ticket.bytes = orig_bytes;
1721		ticket.error = 0;
1722		space_info->reclaim_size += ticket.bytes;
1723		init_waitqueue_head(&ticket.wait);
1724		ticket.steal = can_steal(flush);
1725		if (trace_btrfs_reserve_ticket_enabled())
1726			start_ns = ktime_get_ns();
1727
1728		if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1729		    flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
1730		    flush == BTRFS_RESERVE_FLUSH_DATA) {
1731			list_add_tail(&ticket.list, &space_info->tickets);
1732			if (!space_info->flush) {
1733				/*
1734				 * We were forced to add a reserve ticket, so
1735				 * our preemptive flushing is unable to keep
1736				 * up.  Clamp down on the threshold for the
1737				 * preemptive flushing in order to keep up with
1738				 * the workload.
1739				 */
1740				maybe_clamp_preempt(fs_info, space_info);
1741
1742				space_info->flush = 1;
1743				trace_btrfs_trigger_flush(fs_info,
1744							  space_info->flags,
1745							  orig_bytes, flush,
1746							  "enospc");
1747				queue_work(system_unbound_wq, async_work);
1748			}
1749		} else {
1750			list_add_tail(&ticket.list,
1751				      &space_info->priority_tickets);
1752		}
1753	} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1754		/*
1755		 * We will do the space reservation dance during log replay,
1756		 * which means we won't have fs_info->fs_root set, so don't do
1757		 * the async reclaim as we will panic.
1758		 */
1759		if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1760		    !work_busy(&fs_info->preempt_reclaim_work) &&
1761		    need_preemptive_reclaim(fs_info, space_info)) {
1762			trace_btrfs_trigger_flush(fs_info, space_info->flags,
1763						  orig_bytes, flush, "preempt");
1764			queue_work(system_unbound_wq,
1765				   &fs_info->preempt_reclaim_work);
1766		}
1767	}
1768	spin_unlock(&space_info->lock);
1769	if (!ret || !can_ticket(flush))
1770		return ret;
1771
1772	return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
1773				     orig_bytes, flush);
1774}
1775
1776/*
1777 * Try to reserve metadata bytes from the block_rsv's space.
1778 *
1779 * @fs_info:    the filesystem
1780 * @space_info: the space_info we're allocating for
1781 * @orig_bytes: number of bytes we want
1782 * @flush:      whether or not we can flush to make our reservation
1783 *
1784 * This will reserve orig_bytes number of bytes from the space info associated
1785 * with the block_rsv.  If there is not enough space it will make an attempt to
1786 * flush out space to make room.  It will do this by flushing delalloc if
1787 * possible or committing the transaction.  If flush is 0 then no attempts to
1788 * regain reservations will be made and this will fail if there is not enough
1789 * space already.
1790 */
1791int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1792				 struct btrfs_space_info *space_info,
1793				 u64 orig_bytes,
1794				 enum btrfs_reserve_flush_enum flush)
1795{
1796	int ret;
1797
1798	ret = __reserve_bytes(fs_info, space_info, orig_bytes, flush);
1799	if (ret == -ENOSPC) {
1800		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1801					      space_info->flags, orig_bytes, 1);
1802
1803		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1804			btrfs_dump_space_info(fs_info, space_info, orig_bytes, 0);
1805	}
1806	return ret;
1807}
1808
1809/*
1810 * Try to reserve data bytes for an allocation.
1811 *
1812 * @fs_info: the filesystem
1813 * @bytes:   number of bytes we need
1814 * @flush:   how we are allowed to flush
1815 *
1816 * This will reserve bytes from the data space info.  If there is not enough
1817 * space then we will attempt to flush space as specified by flush.
1818 */
1819int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
1820			     enum btrfs_reserve_flush_enum flush)
1821{
1822	struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
1823	int ret;
1824
1825	ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
1826	       flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE ||
1827	       flush == BTRFS_RESERVE_NO_FLUSH);
1828	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
1829
1830	ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
1831	if (ret == -ENOSPC) {
1832		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1833					      data_sinfo->flags, bytes, 1);
1834		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1835			btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
1836	}
1837	return ret;
1838}
1839
1840/* Dump all the space infos when we abort a transaction due to ENOSPC. */
1841__cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
1842{
1843	struct btrfs_space_info *space_info;
1844
1845	btrfs_info(fs_info, "dumping space info:");
1846	list_for_each_entry(space_info, &fs_info->space_info, list) {
1847		spin_lock(&space_info->lock);
1848		__btrfs_dump_space_info(fs_info, space_info);
1849		spin_unlock(&space_info->lock);
1850	}
1851	dump_global_block_rsv(fs_info);
1852}
1853
1854/*
1855 * Account the unused space of all the readonly block group in the space_info.
1856 * takes mirrors into account.
1857 */
1858u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
1859{
1860	struct btrfs_block_group *block_group;
1861	u64 free_bytes = 0;
1862	int factor;
1863
1864	/* It's df, we don't care if it's racy */
1865	if (list_empty(&sinfo->ro_bgs))
1866		return 0;
1867
1868	spin_lock(&sinfo->lock);
1869	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
1870		spin_lock(&block_group->lock);
1871
1872		if (!block_group->ro) {
1873			spin_unlock(&block_group->lock);
1874			continue;
1875		}
1876
1877		factor = btrfs_bg_type_to_factor(block_group->flags);
1878		free_bytes += (block_group->length -
1879			       block_group->used) * factor;
1880
1881		spin_unlock(&block_group->lock);
1882	}
1883	spin_unlock(&sinfo->lock);
1884
1885	return free_bytes;
1886}
1887
1888static u64 calc_pct_ratio(u64 x, u64 y)
1889{
1890	int err;
1891
1892	if (!y)
1893		return 0;
1894again:
1895	err = check_mul_overflow(100, x, &x);
1896	if (err)
1897		goto lose_precision;
1898	return div64_u64(x, y);
1899lose_precision:
1900	x >>= 10;
1901	y >>= 10;
1902	if (!y)
1903		y = 1;
1904	goto again;
1905}
1906
1907/*
1908 * A reasonable buffer for unallocated space is 10 data block_groups.
1909 * If we claw this back repeatedly, we can still achieve efficient
1910 * utilization when near full, and not do too much reclaim while
1911 * always maintaining a solid buffer for workloads that quickly
1912 * allocate and pressure the unallocated space.
1913 */
1914static u64 calc_unalloc_target(struct btrfs_fs_info *fs_info)
1915{
1916	u64 chunk_sz = calc_effective_data_chunk_size(fs_info);
1917
1918	return BTRFS_UNALLOC_BLOCK_GROUP_TARGET * chunk_sz;
1919}
1920
1921/*
1922 * The fundamental goal of automatic reclaim is to protect the filesystem's
1923 * unallocated space and thus minimize the probability of the filesystem going
1924 * read only when a metadata allocation failure causes a transaction abort.
1925 *
1926 * However, relocations happen into the space_info's unused space, therefore
1927 * automatic reclaim must also back off as that space runs low. There is no
1928 * value in doing trivial "relocations" of re-writing the same block group
1929 * into a fresh one.
1930 *
1931 * Furthermore, we want to avoid doing too much reclaim even if there are good
1932 * candidates. This is because the allocator is pretty good at filling up the
1933 * holes with writes. So we want to do just enough reclaim to try and stay
1934 * safe from running out of unallocated space but not be wasteful about it.
1935 *
1936 * Therefore, the dynamic reclaim threshold is calculated as follows:
1937 * - calculate a target unallocated amount of 5 block group sized chunks
1938 * - ratchet up the intensity of reclaim depending on how far we are from
1939 *   that target by using a formula of unalloc / target to set the threshold.
1940 *
1941 * Typically with 10 block groups as the target, the discrete values this comes
1942 * out to are 0, 10, 20, ... , 80, 90, and 99.
1943 */
1944static int calc_dynamic_reclaim_threshold(const struct btrfs_space_info *space_info)
1945{
1946	struct btrfs_fs_info *fs_info = space_info->fs_info;
1947	u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
1948	u64 target = calc_unalloc_target(fs_info);
1949	u64 alloc = space_info->total_bytes;
1950	u64 used = btrfs_space_info_used(space_info, false);
1951	u64 unused = alloc - used;
1952	u64 want = target > unalloc ? target - unalloc : 0;
1953	u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
1954
1955	/* If we have no unused space, don't bother, it won't work anyway. */
1956	if (unused < data_chunk_size)
1957		return 0;
1958
1959	/* Cast to int is OK because want <= target. */
1960	return calc_pct_ratio(want, target);
1961}
1962
1963int btrfs_calc_reclaim_threshold(const struct btrfs_space_info *space_info)
1964{
1965	lockdep_assert_held(&space_info->lock);
1966
1967	if (READ_ONCE(space_info->dynamic_reclaim))
1968		return calc_dynamic_reclaim_threshold(space_info);
1969	return READ_ONCE(space_info->bg_reclaim_threshold);
1970}
1971
1972/*
1973 * Under "urgent" reclaim, we will reclaim even fresh block groups that have
1974 * recently seen successful allocations, as we are desperate to reclaim
1975 * whatever we can to avoid ENOSPC in a transaction leading to a readonly fs.
1976 */
1977static bool is_reclaim_urgent(struct btrfs_space_info *space_info)
1978{
1979	struct btrfs_fs_info *fs_info = space_info->fs_info;
1980	u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
1981	u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
1982
1983	return unalloc < data_chunk_size;
1984}
1985
1986static void do_reclaim_sweep(struct btrfs_space_info *space_info, int raid)
1987{
1988	struct btrfs_block_group *bg;
1989	int thresh_pct;
1990	bool try_again = true;
1991	bool urgent;
1992
1993	spin_lock(&space_info->lock);
1994	urgent = is_reclaim_urgent(space_info);
1995	thresh_pct = btrfs_calc_reclaim_threshold(space_info);
1996	spin_unlock(&space_info->lock);
1997
1998	down_read(&space_info->groups_sem);
1999again:
2000	list_for_each_entry(bg, &space_info->block_groups[raid], list) {
2001		u64 thresh;
2002		bool reclaim = false;
2003
2004		btrfs_get_block_group(bg);
2005		spin_lock(&bg->lock);
2006		thresh = mult_perc(bg->length, thresh_pct);
2007		if (bg->used < thresh && bg->reclaim_mark) {
2008			try_again = false;
2009			reclaim = true;
2010		}
2011		bg->reclaim_mark++;
2012		spin_unlock(&bg->lock);
2013		if (reclaim)
2014			btrfs_mark_bg_to_reclaim(bg);
2015		btrfs_put_block_group(bg);
2016	}
2017
2018	/*
2019	 * In situations where we are very motivated to reclaim (low unalloc)
2020	 * use two passes to make the reclaim mark check best effort.
2021	 *
2022	 * If we have any staler groups, we don't touch the fresher ones, but if we
2023	 * really need a block group, do take a fresh one.
2024	 */
2025	if (try_again && urgent) {
2026		try_again = false;
2027		goto again;
2028	}
2029
2030	up_read(&space_info->groups_sem);
2031}
2032
2033void btrfs_space_info_update_reclaimable(struct btrfs_space_info *space_info, s64 bytes)
2034{
2035	u64 chunk_sz = calc_effective_data_chunk_size(space_info->fs_info);
2036
2037	lockdep_assert_held(&space_info->lock);
2038	space_info->reclaimable_bytes += bytes;
2039
2040	if (space_info->reclaimable_bytes >= chunk_sz)
2041		btrfs_set_periodic_reclaim_ready(space_info, true);
2042}
2043
2044void btrfs_set_periodic_reclaim_ready(struct btrfs_space_info *space_info, bool ready)
2045{
2046	lockdep_assert_held(&space_info->lock);
2047	if (!READ_ONCE(space_info->periodic_reclaim))
2048		return;
2049	if (ready != space_info->periodic_reclaim_ready) {
2050		space_info->periodic_reclaim_ready = ready;
2051		if (!ready)
2052			space_info->reclaimable_bytes = 0;
2053	}
2054}
2055
2056bool btrfs_should_periodic_reclaim(struct btrfs_space_info *space_info)
2057{
2058	bool ret;
2059
2060	if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
2061		return false;
2062	if (!READ_ONCE(space_info->periodic_reclaim))
2063		return false;
2064
2065	spin_lock(&space_info->lock);
2066	ret = space_info->periodic_reclaim_ready;
2067	btrfs_set_periodic_reclaim_ready(space_info, false);
2068	spin_unlock(&space_info->lock);
2069
2070	return ret;
2071}
2072
2073void btrfs_reclaim_sweep(const struct btrfs_fs_info *fs_info)
2074{
2075	int raid;
2076	struct btrfs_space_info *space_info;
2077
2078	list_for_each_entry(space_info, &fs_info->space_info, list) {
2079		if (!btrfs_should_periodic_reclaim(space_info))
2080			continue;
2081		for (raid = 0; raid < BTRFS_NR_RAID_TYPES; raid++)
2082			do_reclaim_sweep(space_info, raid);
2083	}
2084}