fs/btrfs/space-info.c

   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
  13 /*
  14  * HOW DOES SPACE RESERVATION WORK
  15  *
  16  * If you want to know about delalloc specifically, there is a separate comment
  17  * for that with the delalloc code.  This comment is about how the whole system
  18  * works generally.
  19  *
  20  * BASIC CONCEPTS
  21  *
  22  *   1) space_info.  This is the ultimate arbiter of how much space we can use.
  23  *   There's a description of the bytes_ fields with the struct declaration,
  24  *   refer to that for specifics on each field.  Suffice it to say that for
  25  *   reservations we care about total_bytes - SUM(space_info->bytes_) when
  26  *   determining if there is space to make an allocation.  There is a space_info
  27  *   for METADATA, SYSTEM, and DATA areas.
  28  *
  29  *   2) block_rsv's.  These are basically buckets for every different type of
  30  *   metadata reservation we have.  You can see the comment in the block_rsv
  31  *   code on the rules for each type, but generally block_rsv->reserved is how
  32  *   much space is accounted for in space_info->bytes_may_use.
  33  *
  34  *   3) btrfs_calc*_size.  These are the worst case calculations we used based
  35  *   on the number of items we will want to modify.  We have one for changing
  36  *   items, and one for inserting new items.  Generally we use these helpers to
  37  *   determine the size of the block reserves, and then use the actual bytes
  38  *   values to adjust the space_info counters.
  39  *
  40  * MAKING RESERVATIONS, THE NORMAL CASE
  41  *
  42  *   We call into either btrfs_reserve_data_bytes() or
  43  *   btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
  44  *   num_bytes we want to reserve.
  45  *
  46  *   ->reserve
  47  *     space_info->bytes_may_reserve += num_bytes
  48  *
  49  *   ->extent allocation
  50  *     Call btrfs_add_reserved_bytes() which does
  51  *     space_info->bytes_may_reserve -= num_bytes
  52  *     space_info->bytes_reserved += extent_bytes
  53  *
  54  *   ->insert reference
  55  *     Call btrfs_update_block_group() which does
  56  *     space_info->bytes_reserved -= extent_bytes
  57  *     space_info->bytes_used += extent_bytes
  58  *
  59  * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
  60  *
  61  *   Assume we are unable to simply make the reservation because we do not have
  62  *   enough space
  63  *
  64  *   -> __reserve_bytes
  65  *     create a reserve_ticket with ->bytes set to our reservation, add it to
  66  *     the tail of space_info->tickets, kick async flush thread
  67  *
  68  *   ->handle_reserve_ticket
  69  *     wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
  70  *     on the ticket.
  71  *
  72  *   -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
  73  *     Flushes various things attempting to free up space.
  74  *
  75  *   -> btrfs_try_granting_tickets()
  76  *     This is called by anything that either subtracts space from
  77  *     space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
  78  *     space_info->total_bytes.  This loops through the ->priority_tickets and
  79  *     then the ->tickets list checking to see if the reservation can be
  80  *     completed.  If it can the space is added to space_info->bytes_may_use and
  81  *     the ticket is woken up.
  82  *
  83  *   -> ticket wakeup
  84  *     Check if ->bytes == 0, if it does we got our reservation and we can carry
  85  *     on, if not return the appropriate error (ENOSPC, but can be EINTR if we
  86  *     were interrupted.)
  87  *
  88  * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
  89  *
  90  *   Same as the above, except we add ourselves to the
  91  *   space_info->priority_tickets, and we do not use ticket->wait, we simply
  92  *   call flush_space() ourselves for the states that are safe for us to call
  93  *   without deadlocking and hope for the best.
  94  *
  95  * THE FLUSHING STATES
  96  *
  97  *   Generally speaking we will have two cases for each state, a "nice" state
  98  *   and a "ALL THE THINGS" state.  In btrfs we delay a lot of work in order to
  99  *   reduce the locking over head on the various trees, and even to keep from
 100  *   doing any work at all in the case of delayed refs.  Each of these delayed
 101  *   things however hold reservations, and so letting them run allows us to
 102  *   reclaim space so we can make new reservations.
 103  *
 104  *   FLUSH_DELAYED_ITEMS
 105  *     Every inode has a delayed item to update the inode.  Take a simple write
 106  *     for example, we would update the inode item at write time to update the
 107  *     mtime, and then again at finish_ordered_io() time in order to update the
 108  *     isize or bytes.  We keep these delayed items to coalesce these operations
 109  *     into a single operation done on demand.  These are an easy way to reclaim
 110  *     metadata space.
 111  *
 112  *   FLUSH_DELALLOC
 113  *     Look at the delalloc comment to get an idea of how much space is reserved
 114  *     for delayed allocation.  We can reclaim some of this space simply by
 115  *     running delalloc, but usually we need to wait for ordered extents to
 116  *     reclaim the bulk of this space.
 117  *
 118  *   FLUSH_DELAYED_REFS
 119  *     We have a block reserve for the outstanding delayed refs space, and every
 120  *     delayed ref operation holds a reservation.  Running these is a quick way
 121  *     to reclaim space, but we want to hold this until the end because COW can
 122  *     churn a lot and we can avoid making some extent tree modifications if we
 123  *     are able to delay for as long as possible.
 124  *
 125  *   ALLOC_CHUNK
 126  *     We will skip this the first time through space reservation, because of
 127  *     overcommit and we don't want to have a lot of useless metadata space when
 128  *     our worst case reservations will likely never come true.
 129  *
 130  *   RUN_DELAYED_IPUTS
 131  *     If we're freeing inodes we're likely freeing checksums, file extent
 132  *     items, and extent tree items.  Loads of space could be freed up by these
 133  *     operations, however they won't be usable until the transaction commits.
 134  *
 135  *   COMMIT_TRANS
 136  *     may_commit_transaction() is the ultimate arbiter on whether we commit the
 137  *     transaction or not.  In order to avoid constantly churning we do all the
 138  *     above flushing first and then commit the transaction as the last resort.
 139  *     However we need to take into account things like pinned space that would
 140  *     be freed, plus any delayed work we may not have gotten rid of in the case
 141  *     of metadata.
 142  *
 143  * OVERCOMMIT
 144  *
 145  *   Because we hold so many reservations for metadata we will allow you to
 146  *   reserve more space than is currently free in the currently allocate
 147  *   metadata space.  This only happens with metadata, data does not allow
 148  *   overcommitting.
 149  *
 150  *   You can see the current logic for when we allow overcommit in
 151  *   btrfs_can_overcommit(), but it only applies to unallocated space.  If there
 152  *   is no unallocated space to be had, all reservations are kept within the
 153  *   free space in the allocated metadata chunks.
 154  *
 155  *   Because of overcommitting, you generally want to use the
 156  *   btrfs_can_overcommit() logic for metadata allocations, as it does the right
 157  *   thing with or without extra unallocated space.
 158  */
 159
 160 u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
 161                           bool may_use_included)
 162 {
 163         ASSERT(s_info);
 164         return s_info->bytes_used + s_info->bytes_reserved +
 165                 s_info->bytes_pinned + s_info->bytes_readonly +
 166                 (may_use_included ? s_info->bytes_may_use : 0);
 167 }
 168
 169 /*
 170  * after adding space to the filesystem, we need to clear the full flags
 171  * on all the space infos.
 172  */
 173 void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
 174 {
 175         struct list_head *head = &info->space_info;
 176         struct btrfs_space_info *found;
 177
 178         rcu_read_lock();
 179         list_for_each_entry_rcu(found, head, list)
 180                 found->full = 0;
 181         rcu_read_unlock();
 182 }
 183
 184 static int create_space_info(struct btrfs_fs_info *info, u64 flags)
 185 {
 186
 187         struct btrfs_space_info *space_info;
 188         int i;
 189         int ret;
 190
 191         space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
 192         if (!space_info)
 193                 return -ENOMEM;
 194
 195         ret = percpu_counter_init(&space_info->total_bytes_pinned, 0,
 196                                  GFP_KERNEL);
 197         if (ret) {
 198                 kfree(space_info);
 199                 return ret;
 200         }
 201
 202         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
 203                 INIT_LIST_HEAD(&space_info->block_groups[i]);
 204         init_rwsem(&space_info->groups_sem);
 205         spin_lock_init(&space_info->lock);
 206         space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
 207         space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
 208         INIT_LIST_HEAD(&space_info->ro_bgs);
 209         INIT_LIST_HEAD(&space_info->tickets);
 210         INIT_LIST_HEAD(&space_info->priority_tickets);
 211
 212         ret = btrfs_sysfs_add_space_info_type(info, space_info);
 213         if (ret)
 214                 return ret;
 215
 216         list_add_rcu(&space_info->list, &info->space_info);
 217         if (flags & BTRFS_BLOCK_GROUP_DATA)
 218                 info->data_sinfo = space_info;
 219
 220         return ret;
 221 }
 222
 223 int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
 224 {
 225         struct btrfs_super_block *disk_super;
 226         u64 features;
 227         u64 flags;
 228         int mixed = 0;
 229         int ret;
 230
 231         disk_super = fs_info->super_copy;
 232         if (!btrfs_super_root(disk_super))
 233                 return -EINVAL;
 234
 235         features = btrfs_super_incompat_flags(disk_super);
 236         if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
 237                 mixed = 1;
 238
 239         flags = BTRFS_BLOCK_GROUP_SYSTEM;
 240         ret = create_space_info(fs_info, flags);
 241         if (ret)
 242                 goto out;
 243
 244         if (mixed) {
 245                 flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
 246                 ret = create_space_info(fs_info, flags);
 247         } else {
 248                 flags = BTRFS_BLOCK_GROUP_METADATA;
 249                 ret = create_space_info(fs_info, flags);
 250                 if (ret)
 251                         goto out;
 252
 253                 flags = BTRFS_BLOCK_GROUP_DATA;
 254                 ret = create_space_info(fs_info, flags);
 255         }
 256 out:
 257         return ret;
 258 }
 259
 260 void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
 261                              u64 total_bytes, u64 bytes_used,
 262                              u64 bytes_readonly,
 263                              struct btrfs_space_info **space_info)
 264 {
 265         struct btrfs_space_info *found;
 266         int factor;
 267
 268         factor = btrfs_bg_type_to_factor(flags);
 269
 270         found = btrfs_find_space_info(info, flags);
 271         ASSERT(found);
 272         spin_lock(&found->lock);
 273         found->total_bytes += total_bytes;
 274         found->disk_total += total_bytes * factor;
 275         found->bytes_used += bytes_used;
 276         found->disk_used += bytes_used * factor;
 277         found->bytes_readonly += bytes_readonly;
 278         if (total_bytes > 0)
 279                 found->full = 0;
 280         btrfs_try_granting_tickets(info, found);
 281         spin_unlock(&found->lock);
 282         *space_info = found;
 283 }
 284
 285 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 286                                                u64 flags)
 287 {
 288         struct list_head *head = &info->space_info;
 289         struct btrfs_space_info *found;
 290
 291         flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
 292
 293         rcu_read_lock();
 294         list_for_each_entry_rcu(found, head, list) {
 295                 if (found->flags & flags) {
 296                         rcu_read_unlock();
 297                         return found;
 298                 }
 299         }
 300         rcu_read_unlock();
 301         return NULL;
 302 }
 303
 304 static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
 305 {
 306         return (global->size << 1);
 307 }
 308
 309 static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
 310                           struct btrfs_space_info *space_info,
 311                           enum btrfs_reserve_flush_enum flush)
 312 {
 313         u64 profile;
 314         u64 avail;
 315         int factor;
 316
 317         if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
 318                 profile = btrfs_system_alloc_profile(fs_info);
 319         else
 320                 profile = btrfs_metadata_alloc_profile(fs_info);
 321
 322         avail = atomic64_read(&fs_info->free_chunk_space);
 323
 324         /*
 325          * If we have dup, raid1 or raid10 then only half of the free
 326          * space is actually usable.  For raid56, the space info used
 327          * doesn't include the parity drive, so we don't have to
 328          * change the math
 329          */
 330         factor = btrfs_bg_type_to_factor(profile);
 331         avail = div_u64(avail, factor);
 332
 333         /*
 334          * If we aren't flushing all things, let us overcommit up to
 335          * 1/2th of the space. If we can flush, don't let us overcommit
 336          * too much, let it overcommit up to 1/8 of the space.
 337          */
 338         if (flush == BTRFS_RESERVE_FLUSH_ALL)
 339                 avail >>= 3;
 340         else
 341                 avail >>= 1;
 342         return avail;
 343 }
 344
 345 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 346                          struct btrfs_space_info *space_info, u64 bytes,
 347                          enum btrfs_reserve_flush_enum flush)
 348 {
 349         u64 avail;
 350         u64 used;
 351
 352         /* Don't overcommit when in mixed mode */
 353         if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
 354                 return 0;
 355
 356         used = btrfs_space_info_used(space_info, true);
 357         avail = calc_available_free_space(fs_info, space_info, flush);
 358
 359         if (used + bytes < space_info->total_bytes + avail)
 360                 return 1;
 361         return 0;
 362 }
 363
 364 static void remove_ticket(struct btrfs_space_info *space_info,
 365                           struct reserve_ticket *ticket)
 366 {
 367         if (!list_empty(&ticket->list)) {
 368                 list_del_init(&ticket->list);
 369                 ASSERT(space_info->reclaim_size >= ticket->bytes);
 370                 space_info->reclaim_size -= ticket->bytes;
 371         }
 372 }
 373
 374 /*
 375  * This is for space we already have accounted in space_info->bytes_may_use, so
 376  * basically when we're returning space from block_rsv's.
 377  */
 378 void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
 379                                 struct btrfs_space_info *space_info)
 380 {
 381         struct list_head *head;
 382         enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
 383
 384         lockdep_assert_held(&space_info->lock);
 385
 386         head = &space_info->priority_tickets;
 387 again:
 388         while (!list_empty(head)) {
 389                 struct reserve_ticket *ticket;
 390                 u64 used = btrfs_space_info_used(space_info, true);
 391
 392                 ticket = list_first_entry(head, struct reserve_ticket, list);
 393
 394                 /* Check and see if our ticket can be satisified now. */
 395                 if ((used + ticket->bytes <= space_info->total_bytes) ||
 396                     btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
 397                                          flush)) {
 398                         btrfs_space_info_update_bytes_may_use(fs_info,
 399                                                               space_info,
 400                                                               ticket->bytes);
 401                         remove_ticket(space_info, ticket);
 402                         ticket->bytes = 0;
 403                         space_info->tickets_id++;
 404                         wake_up(&ticket->wait);
 405                 } else {
 406                         break;
 407                 }
 408         }
 409
 410         if (head == &space_info->priority_tickets) {
 411                 head = &space_info->tickets;
 412                 flush = BTRFS_RESERVE_FLUSH_ALL;
 413                 goto again;
 414         }
 415 }
 416
 417 #define DUMP_BLOCK_RSV(fs_info, rsv_name)                               \
 418 do {                                                                    \
 419         struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name;           \
 420         spin_lock(&__rsv->lock);                                        \
 421         btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu",      \
 422                    __rsv->size, __rsv->reserved);                       \
 423         spin_unlock(&__rsv->lock);                                      \
 424 } while (0)
 425
 426 static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 427                                     struct btrfs_space_info *info)
 428 {
 429         lockdep_assert_held(&info->lock);
 430
 431         btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
 432                    info->flags,
 433                    info->total_bytes - btrfs_space_info_used(info, true),
 434                    info->full ? "" : "not ");
 435         btrfs_info(fs_info,
 436                 "space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu",
 437                 info->total_bytes, info->bytes_used, info->bytes_pinned,
 438                 info->bytes_reserved, info->bytes_may_use,
 439                 info->bytes_readonly);
 440
 441         DUMP_BLOCK_RSV(fs_info, global_block_rsv);
 442         DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
 443         DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
 444         DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
 445         DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
 446
 447 }
 448
 449 void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 450                            struct btrfs_space_info *info, u64 bytes,
 451                            int dump_block_groups)
 452 {
 453         struct btrfs_block_group *cache;
 454         int index = 0;
 455
 456         spin_lock(&info->lock);
 457         __btrfs_dump_space_info(fs_info, info);
 458         spin_unlock(&info->lock);
 459
 460         if (!dump_block_groups)
 461                 return;
 462
 463         down_read(&info->groups_sem);
 464 again:
 465         list_for_each_entry(cache, &info->block_groups[index], list) {
 466                 spin_lock(&cache->lock);
 467                 btrfs_info(fs_info,
 468                         "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %s",
 469                         cache->start, cache->length, cache->used, cache->pinned,
 470                         cache->reserved, cache->ro ? "[readonly]" : "");
 471                 btrfs_dump_free_space(cache, bytes);
 472                 spin_unlock(&cache->lock);
 473         }
 474         if (++index < BTRFS_NR_RAID_TYPES)
 475                 goto again;
 476         up_read(&info->groups_sem);
 477 }
 478
 479 static void btrfs_writeback_inodes_sb_nr(struct btrfs_fs_info *fs_info,
 480                                          unsigned long nr_pages, int nr_items)
 481 {
 482         struct super_block *sb = fs_info->sb;
 483
 484         if (down_read_trylock(&sb->s_umount)) {
 485                 writeback_inodes_sb_nr(sb, nr_pages, WB_REASON_FS_FREE_SPACE);
 486                 up_read(&sb->s_umount);
 487         } else {
 488                 /*
 489                  * We needn't worry the filesystem going from r/w to r/o though
 490                  * we don't acquire ->s_umount mutex, because the filesystem
 491                  * should guarantee the delalloc inodes list be empty after
 492                  * the filesystem is readonly(all dirty pages are written to
 493                  * the disk).
 494                  */
 495                 btrfs_start_delalloc_roots(fs_info, nr_items);
 496                 if (!current->journal_info)
 497                         btrfs_wait_ordered_roots(fs_info, nr_items, 0, (u64)-1);
 498         }
 499 }
 500
 501 static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
 502                                         u64 to_reclaim)
 503 {
 504         u64 bytes;
 505         u64 nr;
 506
 507         bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
 508         nr = div64_u64(to_reclaim, bytes);
 509         if (!nr)
 510                 nr = 1;
 511         return nr;
 512 }
 513
 514 #define EXTENT_SIZE_PER_ITEM    SZ_256K
 515
 516 /*
 517  * shrink metadata reservation for delalloc
 518  */
 519 static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
 520                             u64 orig, bool wait_ordered)
 521 {
 522         struct btrfs_space_info *space_info;
 523         struct btrfs_trans_handle *trans;
 524         u64 delalloc_bytes;
 525         u64 dio_bytes;
 526         u64 async_pages;
 527         u64 items;
 528         long time_left;
 529         unsigned long nr_pages;
 530         int loops;
 531
 532         /* Calc the number of the pages we need flush for space reservation */
 533         items = calc_reclaim_items_nr(fs_info, to_reclaim);
 534         to_reclaim = items * EXTENT_SIZE_PER_ITEM;
 535
 536         trans = (struct btrfs_trans_handle *)current->journal_info;
 537         space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
 538
 539         delalloc_bytes = percpu_counter_sum_positive(
 540                                                 &fs_info->delalloc_bytes);
 541         dio_bytes = percpu_counter_sum_positive(&fs_info->dio_bytes);
 542         if (delalloc_bytes == 0 && dio_bytes == 0) {
 543                 if (trans)
 544                         return;
 545                 if (wait_ordered)
 546                         btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
 547                 return;
 548         }
 549
 550         /*
 551          * If we are doing more ordered than delalloc we need to just wait on
 552          * ordered extents, otherwise we'll waste time trying to flush delalloc
 553          * that likely won't give us the space back we need.
 554          */
 555         if (dio_bytes > delalloc_bytes)
 556                 wait_ordered = true;
 557
 558         loops = 0;
 559         while ((delalloc_bytes || dio_bytes) && loops < 3) {
 560                 nr_pages = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
 561
 562                 /*
 563                  * Triggers inode writeback for up to nr_pages. This will invoke
 564                  * ->writepages callback and trigger delalloc filling
 565                  *  (btrfs_run_delalloc_range()).
 566                  */
 567                 btrfs_writeback_inodes_sb_nr(fs_info, nr_pages, items);
 568
 569                 /*
 570                  * We need to wait for the compressed pages to start before
 571                  * we continue.
 572                  */
 573                 async_pages = atomic_read(&fs_info->async_delalloc_pages);
 574                 if (!async_pages)
 575                         goto skip_async;
 576
 577                 /*
 578                  * Calculate how many compressed pages we want to be written
 579                  * before we continue. I.e if there are more async pages than we
 580                  * require wait_event will wait until nr_pages are written.
 581                  */
 582                 if (async_pages <= nr_pages)
 583                         async_pages = 0;
 584                 else
 585                         async_pages -= nr_pages;
 586
 587                 wait_event(fs_info->async_submit_wait,
 588                            atomic_read(&fs_info->async_delalloc_pages) <=
 589                            (int)async_pages);
 590 skip_async:
 591                 spin_lock(&space_info->lock);
 592                 if (list_empty(&space_info->tickets) &&
 593                     list_empty(&space_info->priority_tickets)) {
 594                         spin_unlock(&space_info->lock);
 595                         break;
 596                 }
 597                 spin_unlock(&space_info->lock);
 598
 599                 loops++;
 600                 if (wait_ordered && !trans) {
 601                         btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
 602                 } else {
 603                         time_left = schedule_timeout_killable(1);
 604                         if (time_left)
 605                                 break;
 606                 }
 607                 delalloc_bytes = percpu_counter_sum_positive(
 608                                                 &fs_info->delalloc_bytes);
 609                 dio_bytes = percpu_counter_sum_positive(&fs_info->dio_bytes);
 610         }
 611 }
 612
 613 /**
 614  * maybe_commit_transaction - possibly commit the transaction if its ok to
 615  * @root - the root we're allocating for
 616  * @bytes - the number of bytes we want to reserve
 617  * @force - force the commit
 618  *
 619  * This will check to make sure that committing the transaction will actually
 620  * get us somewhere and then commit the transaction if it does.  Otherwise it
 621  * will return -ENOSPC.
 622  */
 623 static int may_commit_transaction(struct btrfs_fs_info *fs_info,
 624                                   struct btrfs_space_info *space_info)
 625 {
 626         struct reserve_ticket *ticket = NULL;
 627         struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv;
 628         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
 629         struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
 630         struct btrfs_trans_handle *trans;
 631         u64 bytes_needed;
 632         u64 reclaim_bytes = 0;
 633         u64 cur_free_bytes = 0;
 634
 635         trans = (struct btrfs_trans_handle *)current->journal_info;
 636         if (trans)
 637                 return -EAGAIN;
 638
 639         spin_lock(&space_info->lock);
 640         cur_free_bytes = btrfs_space_info_used(space_info, true);
 641         if (cur_free_bytes < space_info->total_bytes)
 642                 cur_free_bytes = space_info->total_bytes - cur_free_bytes;
 643         else
 644                 cur_free_bytes = 0;
 645
 646         if (!list_empty(&space_info->priority_tickets))
 647                 ticket = list_first_entry(&space_info->priority_tickets,
 648                                           struct reserve_ticket, list);
 649         else if (!list_empty(&space_info->tickets))
 650                 ticket = list_first_entry(&space_info->tickets,
 651                                           struct reserve_ticket, list);
 652         bytes_needed = (ticket) ? ticket->bytes : 0;
 653
 654         if (bytes_needed > cur_free_bytes)
 655                 bytes_needed -= cur_free_bytes;
 656         else
 657                 bytes_needed = 0;
 658         spin_unlock(&space_info->lock);
 659
 660         if (!bytes_needed)
 661                 return 0;
 662
 663         trans = btrfs_join_transaction(fs_info->extent_root);
 664         if (IS_ERR(trans))
 665                 return PTR_ERR(trans);
 666
 667         /*
 668          * See if there is enough pinned space to make this reservation, or if
 669          * we have block groups that are going to be freed, allowing us to
 670          * possibly do a chunk allocation the next loop through.
 671          */
 672         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags) ||
 673             __percpu_counter_compare(&space_info->total_bytes_pinned,
 674                                      bytes_needed,
 675                                      BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0)
 676                 goto commit;
 677
 678         /*
 679          * See if there is some space in the delayed insertion reservation for
 680          * this reservation.
 681          */
 682         if (space_info != delayed_rsv->space_info)
 683                 goto enospc;
 684
 685         spin_lock(&delayed_rsv->lock);
 686         reclaim_bytes += delayed_rsv->reserved;
 687         spin_unlock(&delayed_rsv->lock);
 688
 689         spin_lock(&delayed_refs_rsv->lock);
 690         reclaim_bytes += delayed_refs_rsv->reserved;
 691         spin_unlock(&delayed_refs_rsv->lock);
 692
 693         spin_lock(&trans_rsv->lock);
 694         reclaim_bytes += trans_rsv->reserved;
 695         spin_unlock(&trans_rsv->lock);
 696
 697         if (reclaim_bytes >= bytes_needed)
 698                 goto commit;
 699         bytes_needed -= reclaim_bytes;
 700
 701         if (__percpu_counter_compare(&space_info->total_bytes_pinned,
 702                                    bytes_needed,
 703                                    BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0)
 704                 goto enospc;
 705
 706 commit:
 707         return btrfs_commit_transaction(trans);
 708 enospc:
 709         btrfs_end_transaction(trans);
 710         return -ENOSPC;
 711 }
 712
 713 /*
 714  * Try to flush some data based on policy set by @state. This is only advisory
 715  * and may fail for various reasons. The caller is supposed to examine the
 716  * state of @space_info to detect the outcome.
 717  */
 718 static void flush_space(struct btrfs_fs_info *fs_info,
 719                        struct btrfs_space_info *space_info, u64 num_bytes,
 720                        int state)
 721 {
 722         struct btrfs_root *root = fs_info->extent_root;
 723         struct btrfs_trans_handle *trans;
 724         int nr;
 725         int ret = 0;
 726
 727         switch (state) {
 728         case FLUSH_DELAYED_ITEMS_NR:
 729         case FLUSH_DELAYED_ITEMS:
 730                 if (state == FLUSH_DELAYED_ITEMS_NR)
 731                         nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
 732                 else
 733                         nr = -1;
 734
 735                 trans = btrfs_join_transaction(root);
 736                 if (IS_ERR(trans)) {
 737                         ret = PTR_ERR(trans);
 738                         break;
 739                 }
 740                 ret = btrfs_run_delayed_items_nr(trans, nr);
 741                 btrfs_end_transaction(trans);
 742                 break;
 743         case FLUSH_DELALLOC:
 744         case FLUSH_DELALLOC_WAIT:
 745                 shrink_delalloc(fs_info, num_bytes * 2, num_bytes,
 746                                 state == FLUSH_DELALLOC_WAIT);
 747                 break;
 748         case FLUSH_DELAYED_REFS_NR:
 749         case FLUSH_DELAYED_REFS:
 750                 trans = btrfs_join_transaction(root);
 751                 if (IS_ERR(trans)) {
 752                         ret = PTR_ERR(trans);
 753                         break;
 754                 }
 755                 if (state == FLUSH_DELAYED_REFS_NR)
 756                         nr = calc_reclaim_items_nr(fs_info, num_bytes);
 757                 else
 758                         nr = 0;
 759                 btrfs_run_delayed_refs(trans, nr);
 760                 btrfs_end_transaction(trans);
 761                 break;
 762         case ALLOC_CHUNK:
 763         case ALLOC_CHUNK_FORCE:
 764                 trans = btrfs_join_transaction(root);
 765                 if (IS_ERR(trans)) {
 766                         ret = PTR_ERR(trans);
 767                         break;
 768                 }
 769                 ret = btrfs_chunk_alloc(trans,
 770                                 btrfs_metadata_alloc_profile(fs_info),
 771                                 (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
 772                                         CHUNK_ALLOC_FORCE);
 773                 btrfs_end_transaction(trans);
 774                 if (ret > 0 || ret == -ENOSPC)
 775                         ret = 0;
 776                 break;
 777         case RUN_DELAYED_IPUTS:
 778                 /*
 779                  * If we have pending delayed iputs then we could free up a
 780                  * bunch of pinned space, so make sure we run the iputs before
 781                  * we do our pinned bytes check below.
 782                  */
 783                 btrfs_run_delayed_iputs(fs_info);
 784                 btrfs_wait_on_delayed_iputs(fs_info);
 785                 break;
 786         case COMMIT_TRANS:
 787                 ret = may_commit_transaction(fs_info, space_info);
 788                 break;
 789         default:
 790                 ret = -ENOSPC;
 791                 break;
 792         }
 793
 794         trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
 795                                 ret);
 796         return;
 797 }
 798
 799 static inline u64
 800 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 801                                  struct btrfs_space_info *space_info)
 802 {
 803         u64 used;
 804         u64 avail;
 805         u64 expected;
 806         u64 to_reclaim = space_info->reclaim_size;
 807
 808         lockdep_assert_held(&space_info->lock);
 809
 810         avail = calc_available_free_space(fs_info, space_info,
 811                                           BTRFS_RESERVE_FLUSH_ALL);
 812         used = btrfs_space_info_used(space_info, true);
 813
 814         /*
 815          * We may be flushing because suddenly we have less space than we had
 816          * before, and now we're well over-committed based on our current free
 817          * space.  If that's the case add in our overage so we make sure to put
 818          * appropriate pressure on the flushing state machine.
 819          */
 820         if (space_info->total_bytes + avail < used)
 821                 to_reclaim += used - (space_info->total_bytes + avail);
 822
 823         if (to_reclaim)
 824                 return to_reclaim;
 825
 826         to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
 827         if (btrfs_can_overcommit(fs_info, space_info, to_reclaim,
 828                                  BTRFS_RESERVE_FLUSH_ALL))
 829                 return 0;
 830
 831         used = btrfs_space_info_used(space_info, true);
 832
 833         if (btrfs_can_overcommit(fs_info, space_info, SZ_1M,
 834                                  BTRFS_RESERVE_FLUSH_ALL))
 835                 expected = div_factor_fine(space_info->total_bytes, 95);
 836         else
 837                 expected = div_factor_fine(space_info->total_bytes, 90);
 838
 839         if (used > expected)
 840                 to_reclaim = used - expected;
 841         else
 842                 to_reclaim = 0;
 843         to_reclaim = min(to_reclaim, space_info->bytes_may_use +
 844                                      space_info->bytes_reserved);
 845         return to_reclaim;
 846 }
 847
 848 static inline int need_do_async_reclaim(struct btrfs_fs_info *fs_info,
 849                                         struct btrfs_space_info *space_info,
 850                                         u64 used)
 851 {
 852         u64 thresh = div_factor_fine(space_info->total_bytes, 98);
 853
 854         /* If we're just plain full then async reclaim just slows us down. */
 855         if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
 856                 return 0;
 857
 858         if (!btrfs_calc_reclaim_metadata_size(fs_info, space_info))
 859                 return 0;
 860
 861         return (used >= thresh && !btrfs_fs_closing(fs_info) &&
 862                 !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
 863 }
 864
 865 static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
 866                                   struct btrfs_space_info *space_info,
 867                                   struct reserve_ticket *ticket)
 868 {
 869         struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
 870         u64 min_bytes;
 871
 872         if (global_rsv->space_info != space_info)
 873                 return false;
 874
 875         spin_lock(&global_rsv->lock);
 876         min_bytes = div_factor(global_rsv->size, 5);
 877         if (global_rsv->reserved < min_bytes + ticket->bytes) {
 878                 spin_unlock(&global_rsv->lock);
 879                 return false;
 880         }
 881         global_rsv->reserved -= ticket->bytes;
 882         ticket->bytes = 0;
 883         list_del_init(&ticket->list);
 884         wake_up(&ticket->wait);
 885         space_info->tickets_id++;
 886         if (global_rsv->reserved < global_rsv->size)
 887                 global_rsv->full = 0;
 888         spin_unlock(&global_rsv->lock);
 889
 890         return true;
 891 }
 892
 893 /*
 894  * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets
 895  * @fs_info - fs_info for this fs
 896  * @space_info - the space info we were flushing
 897  *
 898  * We call this when we've exhausted our flushing ability and haven't made
 899  * progress in satisfying tickets.  The reservation code handles tickets in
 900  * order, so if there is a large ticket first and then smaller ones we could
 901  * very well satisfy the smaller tickets.  This will attempt to wake up any
 902  * tickets in the list to catch this case.
 903  *
 904  * This function returns true if it was able to make progress by clearing out
 905  * other tickets, or if it stumbles across a ticket that was smaller than the
 906  * first ticket.
 907  */
 908 static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
 909                                    struct btrfs_space_info *space_info)
 910 {
 911         struct reserve_ticket *ticket;
 912         u64 tickets_id = space_info->tickets_id;
 913         u64 first_ticket_bytes = 0;
 914
 915         if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
 916                 btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
 917                 __btrfs_dump_space_info(fs_info, space_info);
 918         }
 919
 920         while (!list_empty(&space_info->tickets) &&
 921                tickets_id == space_info->tickets_id) {
 922                 ticket = list_first_entry(&space_info->tickets,
 923                                           struct reserve_ticket, list);
 924
 925                 if (ticket->steal &&
 926                     steal_from_global_rsv(fs_info, space_info, ticket))
 927                         return true;
 928
 929                 /*
 930                  * may_commit_transaction will avoid committing the transaction
 931                  * if it doesn't feel like the space reclaimed by the commit
 932                  * would result in the ticket succeeding.  However if we have a
 933                  * smaller ticket in the queue it may be small enough to be
 934                  * satisified by committing the transaction, so if any
 935                  * subsequent ticket is smaller than the first ticket go ahead
 936                  * and send us back for another loop through the enospc flushing
 937                  * code.
 938                  */
 939                 if (first_ticket_bytes == 0)
 940                         first_ticket_bytes = ticket->bytes;
 941                 else if (first_ticket_bytes > ticket->bytes)
 942                         return true;
 943
 944                 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
 945                         btrfs_info(fs_info, "failing ticket with %llu bytes",
 946                                    ticket->bytes);
 947
 948                 remove_ticket(space_info, ticket);
 949                 ticket->error = -ENOSPC;
 950                 wake_up(&ticket->wait);
 951
 952                 /*
 953                  * We're just throwing tickets away, so more flushing may not
 954                  * trip over btrfs_try_granting_tickets, so we need to call it
 955                  * here to see if we can make progress with the next ticket in
 956                  * the list.
 957                  */
 958                 btrfs_try_granting_tickets(fs_info, space_info);
 959         }
 960         return (tickets_id != space_info->tickets_id);
 961 }
 962
 963 /*
 964  * This is for normal flushers, we can wait all goddamned day if we want to.  We
 965  * will loop and continuously try to flush as long as we are making progress.
 966  * We count progress as clearing off tickets each time we have to loop.
 967  */
 968 static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
 969 {
 970         struct btrfs_fs_info *fs_info;
 971         struct btrfs_space_info *space_info;
 972         u64 to_reclaim;
 973         int flush_state;
 974         int commit_cycles = 0;
 975         u64 last_tickets_id;
 976
 977         fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
 978         space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
 979
 980         spin_lock(&space_info->lock);
 981         to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
 982         if (!to_reclaim) {
 983                 space_info->flush = 0;
 984                 spin_unlock(&space_info->lock);
 985                 return;
 986         }
 987         last_tickets_id = space_info->tickets_id;
 988         spin_unlock(&space_info->lock);
 989
 990         flush_state = FLUSH_DELAYED_ITEMS_NR;
 991         do {
 992                 flush_space(fs_info, space_info, to_reclaim, flush_state);
 993                 spin_lock(&space_info->lock);
 994                 if (list_empty(&space_info->tickets)) {
 995                         space_info->flush = 0;
 996                         spin_unlock(&space_info->lock);
 997                         return;
 998                 }
 999                 to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
1000                                                               space_info);
1001                 if (last_tickets_id == space_info->tickets_id) {
1002                         flush_state++;
1003                 } else {
1004                         last_tickets_id = space_info->tickets_id;
1005                         flush_state = FLUSH_DELAYED_ITEMS_NR;
1006                         if (commit_cycles)
1007                                 commit_cycles--;
1008                 }
1009
1010                 /*
1011                  * We don't want to force a chunk allocation until we've tried
1012                  * pretty hard to reclaim space.  Think of the case where we
1013                  * freed up a bunch of space and so have a lot of pinned space
1014                  * to reclaim.  We would rather use that than possibly create a
1015                  * underutilized metadata chunk.  So if this is our first run
1016                  * through the flushing state machine skip ALLOC_CHUNK_FORCE and
1017                  * commit the transaction.  If nothing has changed the next go
1018                  * around then we can force a chunk allocation.
1019                  */
1020                 if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
1021                         flush_state++;
1022
1023                 if (flush_state > COMMIT_TRANS) {
1024                         commit_cycles++;
1025                         if (commit_cycles > 2) {
1026                                 if (maybe_fail_all_tickets(fs_info, space_info)) {
1027                                         flush_state = FLUSH_DELAYED_ITEMS_NR;
1028                                         commit_cycles--;
1029                                 } else {
1030                                         space_info->flush = 0;
1031                                 }
1032                         } else {
1033                                 flush_state = FLUSH_DELAYED_ITEMS_NR;
1034                         }
1035                 }
1036                 spin_unlock(&space_info->lock);
1037         } while (flush_state <= COMMIT_TRANS);
1038 }
1039
1040 void btrfs_init_async_reclaim_work(struct work_struct *work)
1041 {
1042         INIT_WORK(work, btrfs_async_reclaim_metadata_space);
1043 }
1044
1045 static const enum btrfs_flush_state priority_flush_states[] = {
1046         FLUSH_DELAYED_ITEMS_NR,
1047         FLUSH_DELAYED_ITEMS,
1048         ALLOC_CHUNK,
1049 };
1050
1051 static const enum btrfs_flush_state evict_flush_states[] = {
1052         FLUSH_DELAYED_ITEMS_NR,
1053         FLUSH_DELAYED_ITEMS,
1054         FLUSH_DELAYED_REFS_NR,
1055         FLUSH_DELAYED_REFS,
1056         FLUSH_DELALLOC,
1057         FLUSH_DELALLOC_WAIT,
1058         ALLOC_CHUNK,
1059         COMMIT_TRANS,
1060 };
1061
1062 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
1063                                 struct btrfs_space_info *space_info,
1064                                 struct reserve_ticket *ticket,
1065                                 const enum btrfs_flush_state *states,
1066                                 int states_nr)
1067 {
1068         u64 to_reclaim;
1069         int flush_state;
1070
1071         spin_lock(&space_info->lock);
1072         to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
1073         if (!to_reclaim) {
1074                 spin_unlock(&space_info->lock);
1075                 return;
1076         }
1077         spin_unlock(&space_info->lock);
1078
1079         flush_state = 0;
1080         do {
1081                 flush_space(fs_info, space_info, to_reclaim, states[flush_state]);
1082                 flush_state++;
1083                 spin_lock(&space_info->lock);
1084                 if (ticket->bytes == 0) {
1085                         spin_unlock(&space_info->lock);
1086                         return;
1087                 }
1088                 spin_unlock(&space_info->lock);
1089         } while (flush_state < states_nr);
1090 }
1091
1092 static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
1093                                 struct btrfs_space_info *space_info,
1094                                 struct reserve_ticket *ticket)
1095
1096 {
1097         DEFINE_WAIT(wait);
1098         int ret = 0;
1099
1100         spin_lock(&space_info->lock);
1101         while (ticket->bytes > 0 && ticket->error == 0) {
1102                 ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
1103                 if (ret) {
1104                         /*
1105                          * Delete us from the list. After we unlock the space
1106                          * info, we don't want the async reclaim job to reserve
1107                          * space for this ticket. If that would happen, then the
1108                          * ticket's task would not known that space was reserved
1109                          * despite getting an error, resulting in a space leak
1110                          * (bytes_may_use counter of our space_info).
1111                          */
1112                         remove_ticket(space_info, ticket);
1113                         ticket->error = -EINTR;
1114                         break;
1115                 }
1116                 spin_unlock(&space_info->lock);
1117
1118                 schedule();
1119
1120                 finish_wait(&ticket->wait, &wait);
1121                 spin_lock(&space_info->lock);
1122         }
1123         spin_unlock(&space_info->lock);
1124 }
1125
1126 /**
1127  * handle_reserve_ticket - do the appropriate flushing and waiting for a ticket
1128  * @fs_info - the fs
1129  * @space_info - the space_info for the reservation
1130  * @ticket - the ticket for the reservation
1131  * @flush - how much we can flush
1132  *
1133  * This does the work of figuring out how to flush for the ticket, waiting for
1134  * the reservation, and returning the appropriate error if there is one.
1135  */
1136 static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
1137                                  struct btrfs_space_info *space_info,
1138                                  struct reserve_ticket *ticket,
1139                                  enum btrfs_reserve_flush_enum flush)
1140 {
1141         int ret;
1142
1143         switch (flush) {
1144         case BTRFS_RESERVE_FLUSH_ALL:
1145         case BTRFS_RESERVE_FLUSH_ALL_STEAL:
1146                 wait_reserve_ticket(fs_info, space_info, ticket);
1147                 break;
1148         case BTRFS_RESERVE_FLUSH_LIMIT:
1149                 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1150                                                 priority_flush_states,
1151                                                 ARRAY_SIZE(priority_flush_states));
1152                 break;
1153         case BTRFS_RESERVE_FLUSH_EVICT:
1154                 priority_reclaim_metadata_space(fs_info, space_info, ticket,
1155                                                 evict_flush_states,
1156                                                 ARRAY_SIZE(evict_flush_states));
1157                 break;
1158         default:
1159                 ASSERT(0);
1160                 break;
1161         }
1162
1163         spin_lock(&space_info->lock);
1164         ret = ticket->error;
1165         if (ticket->bytes || ticket->error) {
1166                 /*
1167                  * Need to delete here for priority tickets. For regular tickets
1168                  * either the async reclaim job deletes the ticket from the list
1169                  * or we delete it ourselves at wait_reserve_ticket().
1170                  */
1171                 remove_ticket(space_info, ticket);
1172                 if (!ret)
1173                         ret = -ENOSPC;
1174         }
1175         spin_unlock(&space_info->lock);
1176         ASSERT(list_empty(&ticket->list));
1177         /*
1178          * Check that we can't have an error set if the reservation succeeded,
1179          * as that would confuse tasks and lead them to error out without
1180          * releasing reserved space (if an error happens the expectation is that
1181          * space wasn't reserved at all).
1182          */
1183         ASSERT(!(ticket->bytes == 0 && ticket->error));
1184         return ret;
1185 }
1186
1187 /**
1188  * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
1189  * @root - the root we're allocating for
1190  * @space_info - the space info we want to allocate from
1191  * @orig_bytes - the number of bytes we want
1192  * @flush - whether or not we can flush to make our reservation
1193  *
1194  * This will reserve orig_bytes number of bytes from the space info associated
1195  * with the block_rsv.  If there is not enough space it will make an attempt to
1196  * flush out space to make room.  It will do this by flushing delalloc if
1197  * possible or committing the transaction.  If flush is 0 then no attempts to
1198  * regain reservations will be made and this will fail if there is not enough
1199  * space already.
1200  */
1201 static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
1202                                     struct btrfs_space_info *space_info,
1203                                     u64 orig_bytes,
1204                                     enum btrfs_reserve_flush_enum flush)
1205 {
1206         struct reserve_ticket ticket;
1207         u64 used;
1208         int ret = 0;
1209         bool pending_tickets;
1210
1211         ASSERT(orig_bytes);
1212         ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
1213
1214         spin_lock(&space_info->lock);
1215         ret = -ENOSPC;
1216         used = btrfs_space_info_used(space_info, true);
1217         pending_tickets = !list_empty(&space_info->tickets) ||
1218                 !list_empty(&space_info->priority_tickets);
1219
1220         /*
1221          * Carry on if we have enough space (short-circuit) OR call
1222          * can_overcommit() to ensure we can overcommit to continue.
1223          */
1224         if (!pending_tickets &&
1225             ((used + orig_bytes <= space_info->total_bytes) ||
1226              btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
1227                 btrfs_space_info_update_bytes_may_use(fs_info, space_info,
1228                                                       orig_bytes);
1229                 ret = 0;
1230         }
1231
1232         /*
1233          * If we couldn't make a reservation then setup our reservation ticket
1234          * and kick the async worker if it's not already running.
1235          *
1236          * If we are a priority flusher then we just need to add our ticket to
1237          * the list and we will do our own flushing further down.
1238          */
1239         if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
1240                 ASSERT(space_info->reclaim_size >= 0);
1241                 ticket.bytes = orig_bytes;
1242                 ticket.error = 0;
1243                 space_info->reclaim_size += ticket.bytes;
1244                 init_waitqueue_head(&ticket.wait);
1245                 ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
1246                 if (flush == BTRFS_RESERVE_FLUSH_ALL ||
1247                     flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {
1248                         list_add_tail(&ticket.list, &space_info->tickets);
1249                         if (!space_info->flush) {
1250                                 space_info->flush = 1;
1251                                 trace_btrfs_trigger_flush(fs_info,
1252                                                           space_info->flags,
1253                                                           orig_bytes, flush,
1254                                                           "enospc");
1255                                 queue_work(system_unbound_wq,
1256                                            &fs_info->async_reclaim_work);
1257                         }
1258                 } else {
1259                         list_add_tail(&ticket.list,
1260                                       &space_info->priority_tickets);
1261                 }
1262         } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
1263                 used += orig_bytes;
1264                 /*
1265                  * We will do the space reservation dance during log replay,
1266                  * which means we won't have fs_info->fs_root set, so don't do
1267                  * the async reclaim as we will panic.
1268                  */
1269                 if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
1270                     need_do_async_reclaim(fs_info, space_info, used) &&
1271                     !work_busy(&fs_info->async_reclaim_work)) {
1272                         trace_btrfs_trigger_flush(fs_info, space_info->flags,
1273                                                   orig_bytes, flush, "preempt");
1274                         queue_work(system_unbound_wq,
1275                                    &fs_info->async_reclaim_work);
1276                 }
1277         }
1278         spin_unlock(&space_info->lock);
1279         if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
1280                 return ret;
1281
1282         return handle_reserve_ticket(fs_info, space_info, &ticket, flush);
1283 }
1284
1285 /**
1286  * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
1287  * @root - the root we're allocating for
1288  * @block_rsv - the block_rsv we're allocating for
1289  * @orig_bytes - the number of bytes we want
1290  * @flush - whether or not we can flush to make our reservation
1291  *
1292  * This will reserve orig_bytes number of bytes from the space info associated
1293  * with the block_rsv.  If there is not enough space it will make an attempt to
1294  * flush out space to make room.  It will do this by flushing delalloc if
1295  * possible or committing the transaction.  If flush is 0 then no attempts to
1296  * regain reservations will be made and this will fail if there is not enough
1297  * space already.
1298  */
1299 int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
1300                                  struct btrfs_block_rsv *block_rsv,
1301                                  u64 orig_bytes,
1302                                  enum btrfs_reserve_flush_enum flush)
1303 {
1304         struct btrfs_fs_info *fs_info = root->fs_info;
1305         struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
1306         int ret;
1307
1308         ret = __reserve_metadata_bytes(fs_info, block_rsv->space_info,
1309                                        orig_bytes, flush);
1310         if (ret == -ENOSPC &&
1311             unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
1312                 if (block_rsv != global_rsv &&
1313                     !btrfs_block_rsv_use_bytes(global_rsv, orig_bytes))
1314                         ret = 0;
1315         }
1316         if (ret == -ENOSPC) {
1317                 trace_btrfs_space_reservation(fs_info, "space_info:enospc",
1318                                               block_rsv->space_info->flags,
1319                                               orig_bytes, 1);
1320
1321                 if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
1322                         btrfs_dump_space_info(fs_info, block_rsv->space_info,
1323                                               orig_bytes, 0);
1324         }
1325         return ret;
1326 }