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