diff options
Diffstat (limited to 'fs/btrfs/space-info.c')
| -rw-r--r-- | fs/btrfs/space-info.c | 1853 |
1 files changed, 1853 insertions, 0 deletions
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c new file mode 100644 index 0000000000..d7e8cd4f14 --- /dev/null +++ b/fs/btrfs/space-info.c @@ -0,0 +1,1853 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "misc.h" +#include "ctree.h" +#include "space-info.h" +#include "sysfs.h" +#include "volumes.h" +#include "free-space-cache.h" +#include "ordered-data.h" +#include "transaction.h" +#include "block-group.h" +#include "zoned.h" +#include "fs.h" +#include "accessors.h" +#include "extent-tree.h" + +/* + * HOW DOES SPACE RESERVATION WORK + * + * If you want to know about delalloc specifically, there is a separate comment + * for that with the delalloc code. This comment is about how the whole system + * works generally. + * + * BASIC CONCEPTS + * + * 1) space_info. This is the ultimate arbiter of how much space we can use. + * There's a description of the bytes_ fields with the struct declaration, + * refer to that for specifics on each field. Suffice it to say that for + * reservations we care about total_bytes - SUM(space_info->bytes_) when + * determining if there is space to make an allocation. There is a space_info + * for METADATA, SYSTEM, and DATA areas. + * + * 2) block_rsv's. These are basically buckets for every different type of + * metadata reservation we have. You can see the comment in the block_rsv + * code on the rules for each type, but generally block_rsv->reserved is how + * much space is accounted for in space_info->bytes_may_use. + * + * 3) btrfs_calc*_size. These are the worst case calculations we used based + * on the number of items we will want to modify. We have one for changing + * items, and one for inserting new items. Generally we use these helpers to + * determine the size of the block reserves, and then use the actual bytes + * values to adjust the space_info counters. + * + * MAKING RESERVATIONS, THE NORMAL CASE + * + * We call into either btrfs_reserve_data_bytes() or + * btrfs_reserve_metadata_bytes(), depending on which we're looking for, with + * num_bytes we want to reserve. + * + * ->reserve + * space_info->bytes_may_reserve += num_bytes + * + * ->extent allocation + * Call btrfs_add_reserved_bytes() which does + * space_info->bytes_may_reserve -= num_bytes + * space_info->bytes_reserved += extent_bytes + * + * ->insert reference + * Call btrfs_update_block_group() which does + * space_info->bytes_reserved -= extent_bytes + * space_info->bytes_used += extent_bytes + * + * MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority) + * + * Assume we are unable to simply make the reservation because we do not have + * enough space + * + * -> __reserve_bytes + * create a reserve_ticket with ->bytes set to our reservation, add it to + * the tail of space_info->tickets, kick async flush thread + * + * ->handle_reserve_ticket + * wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set + * on the ticket. + * + * -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space + * Flushes various things attempting to free up space. + * + * -> btrfs_try_granting_tickets() + * This is called by anything that either subtracts space from + * space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the + * space_info->total_bytes. This loops through the ->priority_tickets and + * then the ->tickets list checking to see if the reservation can be + * completed. If it can the space is added to space_info->bytes_may_use and + * the ticket is woken up. + * + * -> ticket wakeup + * Check if ->bytes == 0, if it does we got our reservation and we can carry + * on, if not return the appropriate error (ENOSPC, but can be EINTR if we + * were interrupted.) + * + * MAKING RESERVATIONS, FLUSHING HIGH PRIORITY + * + * Same as the above, except we add ourselves to the + * space_info->priority_tickets, and we do not use ticket->wait, we simply + * call flush_space() ourselves for the states that are safe for us to call + * without deadlocking and hope for the best. + * + * THE FLUSHING STATES + * + * Generally speaking we will have two cases for each state, a "nice" state + * and a "ALL THE THINGS" state. In btrfs we delay a lot of work in order to + * reduce the locking over head on the various trees, and even to keep from + * doing any work at all in the case of delayed refs. Each of these delayed + * things however hold reservations, and so letting them run allows us to + * reclaim space so we can make new reservations. + * + * FLUSH_DELAYED_ITEMS + * Every inode has a delayed item to update the inode. Take a simple write + * for example, we would update the inode item at write time to update the + * mtime, and then again at finish_ordered_io() time in order to update the + * isize or bytes. We keep these delayed items to coalesce these operations + * into a single operation done on demand. These are an easy way to reclaim + * metadata space. + * + * FLUSH_DELALLOC + * Look at the delalloc comment to get an idea of how much space is reserved + * for delayed allocation. We can reclaim some of this space simply by + * running delalloc, but usually we need to wait for ordered extents to + * reclaim the bulk of this space. + * + * FLUSH_DELAYED_REFS + * We have a block reserve for the outstanding delayed refs space, and every + * delayed ref operation holds a reservation. Running these is a quick way + * to reclaim space, but we want to hold this until the end because COW can + * churn a lot and we can avoid making some extent tree modifications if we + * are able to delay for as long as possible. + * + * ALLOC_CHUNK + * We will skip this the first time through space reservation, because of + * overcommit and we don't want to have a lot of useless metadata space when + * our worst case reservations will likely never come true. + * + * RUN_DELAYED_IPUTS + * If we're freeing inodes we're likely freeing checksums, file extent + * items, and extent tree items. Loads of space could be freed up by these + * operations, however they won't be usable until the transaction commits. + * + * COMMIT_TRANS + * This will commit the transaction. Historically we had a lot of logic + * surrounding whether or not we'd commit the transaction, but this waits born + * out of a pre-tickets era where we could end up committing the transaction + * thousands of times in a row without making progress. Now thanks to our + * ticketing system we know if we're not making progress and can error + * everybody out after a few commits rather than burning the disk hoping for + * a different answer. + * + * OVERCOMMIT + * + * Because we hold so many reservations for metadata we will allow you to + * reserve more space than is currently free in the currently allocate + * metadata space. This only happens with metadata, data does not allow + * overcommitting. + * + * You can see the current logic for when we allow overcommit in + * btrfs_can_overcommit(), but it only applies to unallocated space. If there + * is no unallocated space to be had, all reservations are kept within the + * free space in the allocated metadata chunks. + * + * Because of overcommitting, you generally want to use the + * btrfs_can_overcommit() logic for metadata allocations, as it does the right + * thing with or without extra unallocated space. + */ + +u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info, + bool may_use_included) +{ + ASSERT(s_info); + return s_info->bytes_used + s_info->bytes_reserved + + s_info->bytes_pinned + s_info->bytes_readonly + + s_info->bytes_zone_unusable + + (may_use_included ? s_info->bytes_may_use : 0); +} + +/* + * after adding space to the filesystem, we need to clear the full flags + * on all the space infos. + */ +void btrfs_clear_space_info_full(struct btrfs_fs_info *info) +{ + struct list_head *head = &info->space_info; + struct btrfs_space_info *found; + + list_for_each_entry(found, head, list) + found->full = 0; +} + +/* + * Block groups with more than this value (percents) of unusable space will be + * scheduled for background reclaim. + */ +#define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH (75) + +/* + * Calculate chunk size depending on volume type (regular or zoned). + */ +static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags) +{ + if (btrfs_is_zoned(fs_info)) + return fs_info->zone_size; + + ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK); + + if (flags & BTRFS_BLOCK_GROUP_DATA) + return BTRFS_MAX_DATA_CHUNK_SIZE; + else if (flags & BTRFS_BLOCK_GROUP_SYSTEM) + return SZ_32M; + + /* Handle BTRFS_BLOCK_GROUP_METADATA */ + if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G) + return SZ_1G; + + return SZ_256M; +} + +/* + * Update default chunk size. + */ +void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info, + u64 chunk_size) +{ + WRITE_ONCE(space_info->chunk_size, chunk_size); +} + +static int create_space_info(struct btrfs_fs_info *info, u64 flags) +{ + + struct btrfs_space_info *space_info; + int i; + int ret; + + space_info = kzalloc(sizeof(*space_info), GFP_NOFS); + if (!space_info) + return -ENOMEM; + + for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) + INIT_LIST_HEAD(&space_info->block_groups[i]); + init_rwsem(&space_info->groups_sem); + spin_lock_init(&space_info->lock); + space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK; + space_info->force_alloc = CHUNK_ALLOC_NO_FORCE; + INIT_LIST_HEAD(&space_info->ro_bgs); + INIT_LIST_HEAD(&space_info->tickets); + INIT_LIST_HEAD(&space_info->priority_tickets); + space_info->clamp = 1; + btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags)); + + if (btrfs_is_zoned(info)) + space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH; + + ret = btrfs_sysfs_add_space_info_type(info, space_info); + if (ret) + return ret; + + list_add(&space_info->list, &info->space_info); + if (flags & BTRFS_BLOCK_GROUP_DATA) + info->data_sinfo = space_info; + + return ret; +} + +int btrfs_init_space_info(struct btrfs_fs_info *fs_info) +{ + struct btrfs_super_block *disk_super; + u64 features; + u64 flags; + int mixed = 0; + int ret; + + disk_super = fs_info->super_copy; + if (!btrfs_super_root(disk_super)) + return -EINVAL; + + features = btrfs_super_incompat_flags(disk_super); + if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS) + mixed = 1; + + flags = BTRFS_BLOCK_GROUP_SYSTEM; + ret = create_space_info(fs_info, flags); + if (ret) + goto out; + + if (mixed) { + flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA; + ret = create_space_info(fs_info, flags); + } else { + flags = BTRFS_BLOCK_GROUP_METADATA; + ret = create_space_info(fs_info, flags); + if (ret) + goto out; + + flags = BTRFS_BLOCK_GROUP_DATA; + ret = create_space_info(fs_info, flags); + } +out: + return ret; +} + +void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info, + struct btrfs_block_group *block_group) +{ + struct btrfs_space_info *found; + int factor, index; + + factor = btrfs_bg_type_to_factor(block_group->flags); + + found = btrfs_find_space_info(info, block_group->flags); + ASSERT(found); + spin_lock(&found->lock); + found->total_bytes += block_group->length; + found->disk_total += block_group->length * factor; + found->bytes_used += block_group->used; + found->disk_used += block_group->used * factor; + found->bytes_readonly += block_group->bytes_super; + found->bytes_zone_unusable += block_group->zone_unusable; + if (block_group->length > 0) + found->full = 0; + btrfs_try_granting_tickets(info, found); + spin_unlock(&found->lock); + + block_group->space_info = found; + + index = btrfs_bg_flags_to_raid_index(block_group->flags); + down_write(&found->groups_sem); + list_add_tail(&block_group->list, &found->block_groups[index]); + up_write(&found->groups_sem); +} + +struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info, + u64 flags) +{ + struct list_head *head = &info->space_info; + struct btrfs_space_info *found; + + flags &= BTRFS_BLOCK_GROUP_TYPE_MASK; + + list_for_each_entry(found, head, list) { + if (found->flags & flags) + return found; + } + return NULL; +} + +static u64 calc_available_free_space(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + enum btrfs_reserve_flush_enum flush) +{ + u64 profile; + u64 avail; + int factor; + + if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM) + profile = btrfs_system_alloc_profile(fs_info); + else + profile = btrfs_metadata_alloc_profile(fs_info); + + avail = atomic64_read(&fs_info->free_chunk_space); + + /* + * If we have dup, raid1 or raid10 then only half of the free + * space is actually usable. For raid56, the space info used + * doesn't include the parity drive, so we don't have to + * change the math + */ + factor = btrfs_bg_type_to_factor(profile); + avail = div_u64(avail, factor); + + /* + * If we aren't flushing all things, let us overcommit up to + * 1/2th of the space. If we can flush, don't let us overcommit + * too much, let it overcommit up to 1/8 of the space. + */ + if (flush == BTRFS_RESERVE_FLUSH_ALL) + avail >>= 3; + else + avail >>= 1; + return avail; +} + +int btrfs_can_overcommit(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, u64 bytes, + enum btrfs_reserve_flush_enum flush) +{ + u64 avail; + u64 used; + + /* Don't overcommit when in mixed mode */ + if (space_info->flags & BTRFS_BLOCK_GROUP_DATA) + return 0; + + used = btrfs_space_info_used(space_info, true); + avail = calc_available_free_space(fs_info, space_info, flush); + + if (used + bytes < space_info->total_bytes + avail) + return 1; + return 0; +} + +static void remove_ticket(struct btrfs_space_info *space_info, + struct reserve_ticket *ticket) +{ + if (!list_empty(&ticket->list)) { + list_del_init(&ticket->list); + ASSERT(space_info->reclaim_size >= ticket->bytes); + space_info->reclaim_size -= ticket->bytes; + } +} + +/* + * This is for space we already have accounted in space_info->bytes_may_use, so + * basically when we're returning space from block_rsv's. + */ +void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info) +{ + struct list_head *head; + enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH; + + lockdep_assert_held(&space_info->lock); + + head = &space_info->priority_tickets; +again: + while (!list_empty(head)) { + struct reserve_ticket *ticket; + u64 used = btrfs_space_info_used(space_info, true); + + ticket = list_first_entry(head, struct reserve_ticket, list); + + /* Check and see if our ticket can be satisfied now. */ + if ((used + ticket->bytes <= space_info->total_bytes) || + btrfs_can_overcommit(fs_info, space_info, ticket->bytes, + flush)) { + btrfs_space_info_update_bytes_may_use(fs_info, + space_info, + ticket->bytes); + remove_ticket(space_info, ticket); + ticket->bytes = 0; + space_info->tickets_id++; + wake_up(&ticket->wait); + } else { + break; + } + } + + if (head == &space_info->priority_tickets) { + head = &space_info->tickets; + flush = BTRFS_RESERVE_FLUSH_ALL; + goto again; + } +} + +#define DUMP_BLOCK_RSV(fs_info, rsv_name) \ +do { \ + struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \ + spin_lock(&__rsv->lock); \ + btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \ + __rsv->size, __rsv->reserved); \ + spin_unlock(&__rsv->lock); \ +} while (0) + +static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info) +{ + switch (space_info->flags) { + case BTRFS_BLOCK_GROUP_SYSTEM: + return "SYSTEM"; + case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA: + return "DATA+METADATA"; + case BTRFS_BLOCK_GROUP_DATA: + return "DATA"; + case BTRFS_BLOCK_GROUP_METADATA: + return "METADATA"; + default: + return "UNKNOWN"; + } +} + +static void dump_global_block_rsv(struct btrfs_fs_info *fs_info) +{ + DUMP_BLOCK_RSV(fs_info, global_block_rsv); + DUMP_BLOCK_RSV(fs_info, trans_block_rsv); + DUMP_BLOCK_RSV(fs_info, chunk_block_rsv); + DUMP_BLOCK_RSV(fs_info, delayed_block_rsv); + DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv); +} + +static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *info) +{ + const char *flag_str = space_info_flag_to_str(info); + lockdep_assert_held(&info->lock); + + /* The free space could be negative in case of overcommit */ + btrfs_info(fs_info, "space_info %s has %lld free, is %sfull", + flag_str, + (s64)(info->total_bytes - btrfs_space_info_used(info, true)), + info->full ? "" : "not "); + btrfs_info(fs_info, +"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu", + info->total_bytes, info->bytes_used, info->bytes_pinned, + info->bytes_reserved, info->bytes_may_use, + info->bytes_readonly, info->bytes_zone_unusable); +} + +void btrfs_dump_space_info(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *info, u64 bytes, + int dump_block_groups) +{ + struct btrfs_block_group *cache; + u64 total_avail = 0; + int index = 0; + + spin_lock(&info->lock); + __btrfs_dump_space_info(fs_info, info); + dump_global_block_rsv(fs_info); + spin_unlock(&info->lock); + + if (!dump_block_groups) + return; + + down_read(&info->groups_sem); +again: + list_for_each_entry(cache, &info->block_groups[index], list) { + u64 avail; + + spin_lock(&cache->lock); + avail = cache->length - cache->used - cache->pinned - + cache->reserved - cache->delalloc_bytes - + cache->bytes_super - cache->zone_unusable; + btrfs_info(fs_info, +"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s", + cache->start, cache->length, cache->used, cache->pinned, + cache->reserved, cache->delalloc_bytes, + cache->bytes_super, cache->zone_unusable, + avail, cache->ro ? "[readonly]" : ""); + spin_unlock(&cache->lock); + btrfs_dump_free_space(cache, bytes); + total_avail += avail; + } + if (++index < BTRFS_NR_RAID_TYPES) + goto again; + up_read(&info->groups_sem); + + btrfs_info(fs_info, "%llu bytes available across all block groups", total_avail); +} + +static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info, + u64 to_reclaim) +{ + u64 bytes; + u64 nr; + + bytes = btrfs_calc_insert_metadata_size(fs_info, 1); + nr = div64_u64(to_reclaim, bytes); + if (!nr) + nr = 1; + return nr; +} + +static inline u64 calc_delayed_refs_nr(const struct btrfs_fs_info *fs_info, + u64 to_reclaim) +{ + const u64 bytes = btrfs_calc_delayed_ref_bytes(fs_info, 1); + u64 nr; + + nr = div64_u64(to_reclaim, bytes); + if (!nr) + nr = 1; + return nr; +} + +#define EXTENT_SIZE_PER_ITEM SZ_256K + +/* + * shrink metadata reservation for delalloc + */ +static void shrink_delalloc(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + u64 to_reclaim, bool wait_ordered, + bool for_preempt) +{ + struct btrfs_trans_handle *trans; + u64 delalloc_bytes; + u64 ordered_bytes; + u64 items; + long time_left; + int loops; + + delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes); + ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes); + if (delalloc_bytes == 0 && ordered_bytes == 0) + return; + + /* Calc the number of the pages we need flush for space reservation */ + if (to_reclaim == U64_MAX) { + items = U64_MAX; + } else { + /* + * to_reclaim is set to however much metadata we need to + * reclaim, but reclaiming that much data doesn't really track + * exactly. What we really want to do is reclaim full inode's + * worth of reservations, however that's not available to us + * here. We will take a fraction of the delalloc bytes for our + * flushing loops and hope for the best. Delalloc will expand + * the amount we write to cover an entire dirty extent, which + * will reclaim the metadata reservation for that range. If + * it's not enough subsequent flush stages will be more + * aggressive. + */ + to_reclaim = max(to_reclaim, delalloc_bytes >> 3); + items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2; + } + + trans = current->journal_info; + + /* + * If we are doing more ordered than delalloc we need to just wait on + * ordered extents, otherwise we'll waste time trying to flush delalloc + * that likely won't give us the space back we need. + */ + if (ordered_bytes > delalloc_bytes && !for_preempt) + wait_ordered = true; + + loops = 0; + while ((delalloc_bytes || ordered_bytes) && loops < 3) { + u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT; + long nr_pages = min_t(u64, temp, LONG_MAX); + int async_pages; + + btrfs_start_delalloc_roots(fs_info, nr_pages, true); + + /* + * We need to make sure any outstanding async pages are now + * processed before we continue. This is because things like + * sync_inode() try to be smart and skip writing if the inode is + * marked clean. We don't use filemap_fwrite for flushing + * because we want to control how many pages we write out at a + * time, thus this is the only safe way to make sure we've + * waited for outstanding compressed workers to have started + * their jobs and thus have ordered extents set up properly. + * + * This exists because we do not want to wait for each + * individual inode to finish its async work, we simply want to + * start the IO on everybody, and then come back here and wait + * for all of the async work to catch up. Once we're done with + * that we know we'll have ordered extents for everything and we + * can decide if we wait for that or not. + * + * If we choose to replace this in the future, make absolutely + * sure that the proper waiting is being done in the async case, + * as there have been bugs in that area before. + */ + async_pages = atomic_read(&fs_info->async_delalloc_pages); + if (!async_pages) + goto skip_async; + + /* + * We don't want to wait forever, if we wrote less pages in this + * loop than we have outstanding, only wait for that number of + * pages, otherwise we can wait for all async pages to finish + * before continuing. + */ + if (async_pages > nr_pages) + async_pages -= nr_pages; + else + async_pages = 0; + wait_event(fs_info->async_submit_wait, + atomic_read(&fs_info->async_delalloc_pages) <= + async_pages); +skip_async: + loops++; + if (wait_ordered && !trans) { + btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1); + } else { + time_left = schedule_timeout_killable(1); + if (time_left) + break; + } + + /* + * If we are for preemption we just want a one-shot of delalloc + * flushing so we can stop flushing if we decide we don't need + * to anymore. + */ + if (for_preempt) + break; + + spin_lock(&space_info->lock); + if (list_empty(&space_info->tickets) && + list_empty(&space_info->priority_tickets)) { + spin_unlock(&space_info->lock); + break; + } + spin_unlock(&space_info->lock); + + delalloc_bytes = percpu_counter_sum_positive( + &fs_info->delalloc_bytes); + ordered_bytes = percpu_counter_sum_positive( + &fs_info->ordered_bytes); + } +} + +/* + * Try to flush some data based on policy set by @state. This is only advisory + * and may fail for various reasons. The caller is supposed to examine the + * state of @space_info to detect the outcome. + */ +static void flush_space(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, u64 num_bytes, + enum btrfs_flush_state state, bool for_preempt) +{ + struct btrfs_root *root = fs_info->tree_root; + struct btrfs_trans_handle *trans; + int nr; + int ret = 0; + + switch (state) { + case FLUSH_DELAYED_ITEMS_NR: + case FLUSH_DELAYED_ITEMS: + if (state == FLUSH_DELAYED_ITEMS_NR) + nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2; + else + nr = -1; + + trans = btrfs_join_transaction_nostart(root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + if (ret == -ENOENT) + ret = 0; + break; + } + ret = btrfs_run_delayed_items_nr(trans, nr); + btrfs_end_transaction(trans); + break; + case FLUSH_DELALLOC: + case FLUSH_DELALLOC_WAIT: + case FLUSH_DELALLOC_FULL: + if (state == FLUSH_DELALLOC_FULL) + num_bytes = U64_MAX; + shrink_delalloc(fs_info, space_info, num_bytes, + state != FLUSH_DELALLOC, for_preempt); + break; + case FLUSH_DELAYED_REFS_NR: + case FLUSH_DELAYED_REFS: + trans = btrfs_join_transaction_nostart(root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + if (ret == -ENOENT) + ret = 0; + break; + } + if (state == FLUSH_DELAYED_REFS_NR) + nr = calc_delayed_refs_nr(fs_info, num_bytes); + else + nr = 0; + btrfs_run_delayed_refs(trans, nr); + btrfs_end_transaction(trans); + break; + case ALLOC_CHUNK: + case ALLOC_CHUNK_FORCE: + trans = btrfs_join_transaction(root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + break; + } + ret = btrfs_chunk_alloc(trans, + btrfs_get_alloc_profile(fs_info, space_info->flags), + (state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE : + CHUNK_ALLOC_FORCE); + btrfs_end_transaction(trans); + + if (ret > 0 || ret == -ENOSPC) + ret = 0; + break; + case RUN_DELAYED_IPUTS: + /* + * If we have pending delayed iputs then we could free up a + * bunch of pinned space, so make sure we run the iputs before + * we do our pinned bytes check below. + */ + btrfs_run_delayed_iputs(fs_info); + btrfs_wait_on_delayed_iputs(fs_info); + break; + case COMMIT_TRANS: + ASSERT(current->journal_info == NULL); + /* + * We don't want to start a new transaction, just attach to the + * current one or wait it fully commits in case its commit is + * happening at the moment. Note: we don't use a nostart join + * because that does not wait for a transaction to fully commit + * (only for it to be unblocked, state TRANS_STATE_UNBLOCKED). + */ + trans = btrfs_attach_transaction_barrier(root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + if (ret == -ENOENT) + ret = 0; + break; + } + ret = btrfs_commit_transaction(trans); + break; + default: + ret = -ENOSPC; + break; + } + + trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state, + ret, for_preempt); + return; +} + +static inline u64 +btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info) +{ + u64 used; + u64 avail; + u64 to_reclaim = space_info->reclaim_size; + + lockdep_assert_held(&space_info->lock); + + avail = calc_available_free_space(fs_info, space_info, + BTRFS_RESERVE_FLUSH_ALL); + used = btrfs_space_info_used(space_info, true); + + /* + * We may be flushing because suddenly we have less space than we had + * before, and now we're well over-committed based on our current free + * space. If that's the case add in our overage so we make sure to put + * appropriate pressure on the flushing state machine. + */ + if (space_info->total_bytes + avail < used) + to_reclaim += used - (space_info->total_bytes + avail); + + return to_reclaim; +} + +static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info) +{ + u64 global_rsv_size = fs_info->global_block_rsv.reserved; + u64 ordered, delalloc; + u64 thresh; + u64 used; + + thresh = mult_perc(space_info->total_bytes, 90); + + lockdep_assert_held(&space_info->lock); + + /* If we're just plain full then async reclaim just slows us down. */ + if ((space_info->bytes_used + space_info->bytes_reserved + + global_rsv_size) >= thresh) + return false; + + used = space_info->bytes_may_use + space_info->bytes_pinned; + + /* The total flushable belongs to the global rsv, don't flush. */ + if (global_rsv_size >= used) + return false; + + /* + * 128MiB is 1/4 of the maximum global rsv size. If we have less than + * that devoted to other reservations then there's no sense in flushing, + * we don't have a lot of things that need flushing. + */ + if (used - global_rsv_size <= SZ_128M) + return false; + + /* + * We have tickets queued, bail so we don't compete with the async + * flushers. + */ + if (space_info->reclaim_size) + return false; + + /* + * If we have over half of the free space occupied by reservations or + * pinned then we want to start flushing. + * + * We do not do the traditional thing here, which is to say + * + * if (used >= ((total_bytes + avail) / 2)) + * return 1; + * + * because this doesn't quite work how we want. If we had more than 50% + * of the space_info used by bytes_used and we had 0 available we'd just + * constantly run the background flusher. Instead we want it to kick in + * if our reclaimable space exceeds our clamped free space. + * + * Our clamping range is 2^1 -> 2^8. Practically speaking that means + * the following: + * + * Amount of RAM Minimum threshold Maximum threshold + * + * 256GiB 1GiB 128GiB + * 128GiB 512MiB 64GiB + * 64GiB 256MiB 32GiB + * 32GiB 128MiB 16GiB + * 16GiB 64MiB 8GiB + * + * These are the range our thresholds will fall in, corresponding to how + * much delalloc we need for the background flusher to kick in. + */ + + thresh = calc_available_free_space(fs_info, space_info, + BTRFS_RESERVE_FLUSH_ALL); + used = space_info->bytes_used + space_info->bytes_reserved + + space_info->bytes_readonly + global_rsv_size; + if (used < space_info->total_bytes) + thresh += space_info->total_bytes - used; + thresh >>= space_info->clamp; + + used = space_info->bytes_pinned; + + /* + * If we have more ordered bytes than delalloc bytes then we're either + * doing a lot of DIO, or we simply don't have a lot of delalloc waiting + * around. Preemptive flushing is only useful in that it can free up + * space before tickets need to wait for things to finish. In the case + * of ordered extents, preemptively waiting on ordered extents gets us + * nothing, if our reservations are tied up in ordered extents we'll + * simply have to slow down writers by forcing them to wait on ordered + * extents. + * + * In the case that ordered is larger than delalloc, only include the + * block reserves that we would actually be able to directly reclaim + * from. In this case if we're heavy on metadata operations this will + * clearly be heavy enough to warrant preemptive flushing. In the case + * of heavy DIO or ordered reservations, preemptive flushing will just + * waste time and cause us to slow down. + * + * We want to make sure we truly are maxed out on ordered however, so + * cut ordered in half, and if it's still higher than delalloc then we + * can keep flushing. This is to avoid the case where we start + * flushing, and now delalloc == ordered and we stop preemptively + * flushing when we could still have several gigs of delalloc to flush. + */ + ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1; + delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes); + if (ordered >= delalloc) + used += fs_info->delayed_refs_rsv.reserved + + fs_info->delayed_block_rsv.reserved; + else + used += space_info->bytes_may_use - global_rsv_size; + + return (used >= thresh && !btrfs_fs_closing(fs_info) && + !test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state)); +} + +static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + struct reserve_ticket *ticket) +{ + struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv; + u64 min_bytes; + + if (!ticket->steal) + return false; + + if (global_rsv->space_info != space_info) + return false; + + spin_lock(&global_rsv->lock); + min_bytes = mult_perc(global_rsv->size, 10); + if (global_rsv->reserved < min_bytes + ticket->bytes) { + spin_unlock(&global_rsv->lock); + return false; + } + global_rsv->reserved -= ticket->bytes; + remove_ticket(space_info, ticket); + ticket->bytes = 0; + wake_up(&ticket->wait); + space_info->tickets_id++; + if (global_rsv->reserved < global_rsv->size) + global_rsv->full = 0; + spin_unlock(&global_rsv->lock); + + return true; +} + +/* + * maybe_fail_all_tickets - we've exhausted our flushing, start failing tickets + * @fs_info - fs_info for this fs + * @space_info - the space info we were flushing + * + * We call this when we've exhausted our flushing ability and haven't made + * progress in satisfying tickets. The reservation code handles tickets in + * order, so if there is a large ticket first and then smaller ones we could + * very well satisfy the smaller tickets. This will attempt to wake up any + * tickets in the list to catch this case. + * + * This function returns true if it was able to make progress by clearing out + * other tickets, or if it stumbles across a ticket that was smaller than the + * first ticket. + */ +static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info) +{ + struct reserve_ticket *ticket; + u64 tickets_id = space_info->tickets_id; + const bool aborted = BTRFS_FS_ERROR(fs_info); + + trace_btrfs_fail_all_tickets(fs_info, space_info); + + if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) { + btrfs_info(fs_info, "cannot satisfy tickets, dumping space info"); + __btrfs_dump_space_info(fs_info, space_info); + } + + while (!list_empty(&space_info->tickets) && + tickets_id == space_info->tickets_id) { + ticket = list_first_entry(&space_info->tickets, + struct reserve_ticket, list); + + if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket)) + return true; + + if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG)) + btrfs_info(fs_info, "failing ticket with %llu bytes", + ticket->bytes); + + remove_ticket(space_info, ticket); + if (aborted) + ticket->error = -EIO; + else + ticket->error = -ENOSPC; + wake_up(&ticket->wait); + + /* + * We're just throwing tickets away, so more flushing may not + * trip over btrfs_try_granting_tickets, so we need to call it + * here to see if we can make progress with the next ticket in + * the list. + */ + if (!aborted) + btrfs_try_granting_tickets(fs_info, space_info); + } + return (tickets_id != space_info->tickets_id); +} + +/* + * This is for normal flushers, we can wait all goddamned day if we want to. We + * will loop and continuously try to flush as long as we are making progress. + * We count progress as clearing off tickets each time we have to loop. + */ +static void btrfs_async_reclaim_metadata_space(struct work_struct *work) +{ + struct btrfs_fs_info *fs_info; + struct btrfs_space_info *space_info; + u64 to_reclaim; + enum btrfs_flush_state flush_state; + int commit_cycles = 0; + u64 last_tickets_id; + + fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work); + space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); + + spin_lock(&space_info->lock); + to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); + if (!to_reclaim) { + space_info->flush = 0; + spin_unlock(&space_info->lock); + return; + } + last_tickets_id = space_info->tickets_id; + spin_unlock(&space_info->lock); + + flush_state = FLUSH_DELAYED_ITEMS_NR; + do { + flush_space(fs_info, space_info, to_reclaim, flush_state, false); + spin_lock(&space_info->lock); + if (list_empty(&space_info->tickets)) { + space_info->flush = 0; + spin_unlock(&space_info->lock); + return; + } + to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, + space_info); + if (last_tickets_id == space_info->tickets_id) { + flush_state++; + } else { + last_tickets_id = space_info->tickets_id; + flush_state = FLUSH_DELAYED_ITEMS_NR; + if (commit_cycles) + commit_cycles--; + } + + /* + * We do not want to empty the system of delalloc unless we're + * under heavy pressure, so allow one trip through the flushing + * logic before we start doing a FLUSH_DELALLOC_FULL. + */ + if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles) + flush_state++; + + /* + * We don't want to force a chunk allocation until we've tried + * pretty hard to reclaim space. Think of the case where we + * freed up a bunch of space and so have a lot of pinned space + * to reclaim. We would rather use that than possibly create a + * underutilized metadata chunk. So if this is our first run + * through the flushing state machine skip ALLOC_CHUNK_FORCE and + * commit the transaction. If nothing has changed the next go + * around then we can force a chunk allocation. + */ + if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles) + flush_state++; + + if (flush_state > COMMIT_TRANS) { + commit_cycles++; + if (commit_cycles > 2) { + if (maybe_fail_all_tickets(fs_info, space_info)) { + flush_state = FLUSH_DELAYED_ITEMS_NR; + commit_cycles--; + } else { + space_info->flush = 0; + } + } else { + flush_state = FLUSH_DELAYED_ITEMS_NR; + } + } + spin_unlock(&space_info->lock); + } while (flush_state <= COMMIT_TRANS); +} + +/* + * This handles pre-flushing of metadata space before we get to the point that + * we need to start blocking threads on tickets. The logic here is different + * from the other flush paths because it doesn't rely on tickets to tell us how + * much we need to flush, instead it attempts to keep us below the 80% full + * watermark of space by flushing whichever reservation pool is currently the + * largest. + */ +static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work) +{ + struct btrfs_fs_info *fs_info; + struct btrfs_space_info *space_info; + struct btrfs_block_rsv *delayed_block_rsv; + struct btrfs_block_rsv *delayed_refs_rsv; + struct btrfs_block_rsv *global_rsv; + struct btrfs_block_rsv *trans_rsv; + int loops = 0; + + fs_info = container_of(work, struct btrfs_fs_info, + preempt_reclaim_work); + space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); + delayed_block_rsv = &fs_info->delayed_block_rsv; + delayed_refs_rsv = &fs_info->delayed_refs_rsv; + global_rsv = &fs_info->global_block_rsv; + trans_rsv = &fs_info->trans_block_rsv; + + spin_lock(&space_info->lock); + while (need_preemptive_reclaim(fs_info, space_info)) { + enum btrfs_flush_state flush; + u64 delalloc_size = 0; + u64 to_reclaim, block_rsv_size; + u64 global_rsv_size = global_rsv->reserved; + + loops++; + + /* + * We don't have a precise counter for the metadata being + * reserved for delalloc, so we'll approximate it by subtracting + * out the block rsv's space from the bytes_may_use. If that + * amount is higher than the individual reserves, then we can + * assume it's tied up in delalloc reservations. + */ + block_rsv_size = global_rsv_size + + delayed_block_rsv->reserved + + delayed_refs_rsv->reserved + + trans_rsv->reserved; + if (block_rsv_size < space_info->bytes_may_use) + delalloc_size = space_info->bytes_may_use - block_rsv_size; + + /* + * We don't want to include the global_rsv in our calculation, + * because that's space we can't touch. Subtract it from the + * block_rsv_size for the next checks. + */ + block_rsv_size -= global_rsv_size; + + /* + * We really want to avoid flushing delalloc too much, as it + * could result in poor allocation patterns, so only flush it if + * it's larger than the rest of the pools combined. + */ + if (delalloc_size > block_rsv_size) { + to_reclaim = delalloc_size; + flush = FLUSH_DELALLOC; + } else if (space_info->bytes_pinned > + (delayed_block_rsv->reserved + + delayed_refs_rsv->reserved)) { + to_reclaim = space_info->bytes_pinned; + flush = COMMIT_TRANS; + } else if (delayed_block_rsv->reserved > + delayed_refs_rsv->reserved) { + to_reclaim = delayed_block_rsv->reserved; + flush = FLUSH_DELAYED_ITEMS_NR; + } else { + to_reclaim = delayed_refs_rsv->reserved; + flush = FLUSH_DELAYED_REFS_NR; + } + + spin_unlock(&space_info->lock); + + /* + * We don't want to reclaim everything, just a portion, so scale + * down the to_reclaim by 1/4. If it takes us down to 0, + * reclaim 1 items worth. + */ + to_reclaim >>= 2; + if (!to_reclaim) + to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1); + flush_space(fs_info, space_info, to_reclaim, flush, true); + cond_resched(); + spin_lock(&space_info->lock); + } + + /* We only went through once, back off our clamping. */ + if (loops == 1 && !space_info->reclaim_size) + space_info->clamp = max(1, space_info->clamp - 1); + trace_btrfs_done_preemptive_reclaim(fs_info, space_info); + spin_unlock(&space_info->lock); +} + +/* + * FLUSH_DELALLOC_WAIT: + * Space is freed from flushing delalloc in one of two ways. + * + * 1) compression is on and we allocate less space than we reserved + * 2) we are overwriting existing space + * + * For #1 that extra space is reclaimed as soon as the delalloc pages are + * COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent + * length to ->bytes_reserved, and subtracts the reserved space from + * ->bytes_may_use. + * + * For #2 this is trickier. Once the ordered extent runs we will drop the + * extent in the range we are overwriting, which creates a delayed ref for + * that freed extent. This however is not reclaimed until the transaction + * commits, thus the next stages. + * + * RUN_DELAYED_IPUTS + * If we are freeing inodes, we want to make sure all delayed iputs have + * completed, because they could have been on an inode with i_nlink == 0, and + * thus have been truncated and freed up space. But again this space is not + * immediately re-usable, it comes in the form of a delayed ref, which must be + * run and then the transaction must be committed. + * + * COMMIT_TRANS + * This is where we reclaim all of the pinned space generated by running the + * iputs + * + * ALLOC_CHUNK_FORCE + * For data we start with alloc chunk force, however we could have been full + * before, and then the transaction commit could have freed new block groups, + * so if we now have space to allocate do the force chunk allocation. + */ +static const enum btrfs_flush_state data_flush_states[] = { + FLUSH_DELALLOC_FULL, + RUN_DELAYED_IPUTS, + COMMIT_TRANS, + ALLOC_CHUNK_FORCE, +}; + +static void btrfs_async_reclaim_data_space(struct work_struct *work) +{ + struct btrfs_fs_info *fs_info; + struct btrfs_space_info *space_info; + u64 last_tickets_id; + enum btrfs_flush_state flush_state = 0; + + fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work); + space_info = fs_info->data_sinfo; + + spin_lock(&space_info->lock); + if (list_empty(&space_info->tickets)) { + space_info->flush = 0; + spin_unlock(&space_info->lock); + return; + } + last_tickets_id = space_info->tickets_id; + spin_unlock(&space_info->lock); + + while (!space_info->full) { + flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); + spin_lock(&space_info->lock); + if (list_empty(&space_info->tickets)) { + space_info->flush = 0; + spin_unlock(&space_info->lock); + return; + } + + /* Something happened, fail everything and bail. */ + if (BTRFS_FS_ERROR(fs_info)) + goto aborted_fs; + last_tickets_id = space_info->tickets_id; + spin_unlock(&space_info->lock); + } + + while (flush_state < ARRAY_SIZE(data_flush_states)) { + flush_space(fs_info, space_info, U64_MAX, + data_flush_states[flush_state], false); + spin_lock(&space_info->lock); + if (list_empty(&space_info->tickets)) { + space_info->flush = 0; + spin_unlock(&space_info->lock); + return; + } + + if (last_tickets_id == space_info->tickets_id) { + flush_state++; + } else { + last_tickets_id = space_info->tickets_id; + flush_state = 0; + } + + if (flush_state >= ARRAY_SIZE(data_flush_states)) { + if (space_info->full) { + if (maybe_fail_all_tickets(fs_info, space_info)) + flush_state = 0; + else + space_info->flush = 0; + } else { + flush_state = 0; + } + + /* Something happened, fail everything and bail. */ + if (BTRFS_FS_ERROR(fs_info)) + goto aborted_fs; + + } + spin_unlock(&space_info->lock); + } + return; + +aborted_fs: + maybe_fail_all_tickets(fs_info, space_info); + space_info->flush = 0; + spin_unlock(&space_info->lock); +} + +void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info) +{ + INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space); + INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space); + INIT_WORK(&fs_info->preempt_reclaim_work, + btrfs_preempt_reclaim_metadata_space); +} + +static const enum btrfs_flush_state priority_flush_states[] = { + FLUSH_DELAYED_ITEMS_NR, + FLUSH_DELAYED_ITEMS, + ALLOC_CHUNK, +}; + +static const enum btrfs_flush_state evict_flush_states[] = { + FLUSH_DELAYED_ITEMS_NR, + FLUSH_DELAYED_ITEMS, + FLUSH_DELAYED_REFS_NR, + FLUSH_DELAYED_REFS, + FLUSH_DELALLOC, + FLUSH_DELALLOC_WAIT, + FLUSH_DELALLOC_FULL, + ALLOC_CHUNK, + COMMIT_TRANS, +}; + +static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + struct reserve_ticket *ticket, + const enum btrfs_flush_state *states, + int states_nr) +{ + u64 to_reclaim; + int flush_state = 0; + + spin_lock(&space_info->lock); + to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info); + /* + * This is the priority reclaim path, so to_reclaim could be >0 still + * because we may have only satisfied the priority tickets and still + * left non priority tickets on the list. We would then have + * to_reclaim but ->bytes == 0. + */ + if (ticket->bytes == 0) { + spin_unlock(&space_info->lock); + return; + } + + while (flush_state < states_nr) { + spin_unlock(&space_info->lock); + flush_space(fs_info, space_info, to_reclaim, states[flush_state], + false); + flush_state++; + spin_lock(&space_info->lock); + if (ticket->bytes == 0) { + spin_unlock(&space_info->lock); + return; + } + } + + /* + * Attempt to steal from the global rsv if we can, except if the fs was + * turned into error mode due to a transaction abort when flushing space + * above, in that case fail with the abort error instead of returning + * success to the caller if we can steal from the global rsv - this is + * just to have caller fail immeditelly instead of later when trying to + * modify the fs, making it easier to debug -ENOSPC problems. + */ + if (BTRFS_FS_ERROR(fs_info)) { + ticket->error = BTRFS_FS_ERROR(fs_info); + remove_ticket(space_info, ticket); + } else if (!steal_from_global_rsv(fs_info, space_info, ticket)) { + ticket->error = -ENOSPC; + remove_ticket(space_info, ticket); + } + + /* + * We must run try_granting_tickets here because we could be a large + * ticket in front of a smaller ticket that can now be satisfied with + * the available space. + */ + btrfs_try_granting_tickets(fs_info, space_info); + spin_unlock(&space_info->lock); +} + +static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + struct reserve_ticket *ticket) +{ + spin_lock(&space_info->lock); + + /* We could have been granted before we got here. */ + if (ticket->bytes == 0) { + spin_unlock(&space_info->lock); + return; + } + + while (!space_info->full) { + spin_unlock(&space_info->lock); + flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false); + spin_lock(&space_info->lock); + if (ticket->bytes == 0) { + spin_unlock(&space_info->lock); + return; + } + } + + ticket->error = -ENOSPC; + remove_ticket(space_info, ticket); + btrfs_try_granting_tickets(fs_info, space_info); + spin_unlock(&space_info->lock); +} + +static void wait_reserve_ticket(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + struct reserve_ticket *ticket) + +{ + DEFINE_WAIT(wait); + int ret = 0; + + spin_lock(&space_info->lock); + while (ticket->bytes > 0 && ticket->error == 0) { + ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE); + if (ret) { + /* + * Delete us from the list. After we unlock the space + * info, we don't want the async reclaim job to reserve + * space for this ticket. If that would happen, then the + * ticket's task would not known that space was reserved + * despite getting an error, resulting in a space leak + * (bytes_may_use counter of our space_info). + */ + remove_ticket(space_info, ticket); + ticket->error = -EINTR; + break; + } + spin_unlock(&space_info->lock); + + schedule(); + + finish_wait(&ticket->wait, &wait); + spin_lock(&space_info->lock); + } + spin_unlock(&space_info->lock); +} + +/* + * Do the appropriate flushing and waiting for a ticket. + * + * @fs_info: the filesystem + * @space_info: space info for the reservation + * @ticket: ticket for the reservation + * @start_ns: timestamp when the reservation started + * @orig_bytes: amount of bytes originally reserved + * @flush: how much we can flush + * + * This does the work of figuring out how to flush for the ticket, waiting for + * the reservation, and returning the appropriate error if there is one. + */ +static int handle_reserve_ticket(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, + struct reserve_ticket *ticket, + u64 start_ns, u64 orig_bytes, + enum btrfs_reserve_flush_enum flush) +{ + int ret; + + switch (flush) { + case BTRFS_RESERVE_FLUSH_DATA: + case BTRFS_RESERVE_FLUSH_ALL: + case BTRFS_RESERVE_FLUSH_ALL_STEAL: + wait_reserve_ticket(fs_info, space_info, ticket); + break; + case BTRFS_RESERVE_FLUSH_LIMIT: + priority_reclaim_metadata_space(fs_info, space_info, ticket, + priority_flush_states, + ARRAY_SIZE(priority_flush_states)); + break; + case BTRFS_RESERVE_FLUSH_EVICT: + priority_reclaim_metadata_space(fs_info, space_info, ticket, + evict_flush_states, + ARRAY_SIZE(evict_flush_states)); + break; + case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE: + priority_reclaim_data_space(fs_info, space_info, ticket); + break; + default: + ASSERT(0); + break; + } + + ret = ticket->error; + ASSERT(list_empty(&ticket->list)); + /* + * Check that we can't have an error set if the reservation succeeded, + * as that would confuse tasks and lead them to error out without + * releasing reserved space (if an error happens the expectation is that + * space wasn't reserved at all). + */ + ASSERT(!(ticket->bytes == 0 && ticket->error)); + trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes, + start_ns, flush, ticket->error); + return ret; +} + +/* + * This returns true if this flush state will go through the ordinary flushing + * code. + */ +static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush) +{ + return (flush == BTRFS_RESERVE_FLUSH_ALL) || + (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); +} + +static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info) +{ + u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes); + u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes); + + /* + * If we're heavy on ordered operations then clamping won't help us. We + * need to clamp specifically to keep up with dirty'ing buffered + * writers, because there's not a 1:1 correlation of writing delalloc + * and freeing space, like there is with flushing delayed refs or + * delayed nodes. If we're already more ordered than delalloc then + * we're keeping up, otherwise we aren't and should probably clamp. + */ + if (ordered < delalloc) + space_info->clamp = min(space_info->clamp + 1, 8); +} + +static inline bool can_steal(enum btrfs_reserve_flush_enum flush) +{ + return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL || + flush == BTRFS_RESERVE_FLUSH_EVICT); +} + +/* + * NO_FLUSH and FLUSH_EMERGENCY don't want to create a ticket, they just want to + * fail as quickly as possible. + */ +static inline bool can_ticket(enum btrfs_reserve_flush_enum flush) +{ + return (flush != BTRFS_RESERVE_NO_FLUSH && + flush != BTRFS_RESERVE_FLUSH_EMERGENCY); +} + +/* + * Try to reserve bytes from the block_rsv's space. + * + * @fs_info: the filesystem + * @space_info: space info we want to allocate from + * @orig_bytes: number of bytes we want + * @flush: whether or not we can flush to make our reservation + * + * This will reserve orig_bytes number of bytes from the space info associated + * with the block_rsv. If there is not enough space it will make an attempt to + * flush out space to make room. It will do this by flushing delalloc if + * possible or committing the transaction. If flush is 0 then no attempts to + * regain reservations will be made and this will fail if there is not enough + * space already. + */ +static int __reserve_bytes(struct btrfs_fs_info *fs_info, + struct btrfs_space_info *space_info, u64 orig_bytes, + enum btrfs_reserve_flush_enum flush) +{ + struct work_struct *async_work; + struct reserve_ticket ticket; + u64 start_ns = 0; + u64 used; + int ret = -ENOSPC; + bool pending_tickets; + + ASSERT(orig_bytes); + /* + * If have a transaction handle (current->journal_info != NULL), then + * the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor + * BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those + * flushing methods can trigger transaction commits. + */ + if (current->journal_info) { + /* One assert per line for easier debugging. */ + ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL); + ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL); + ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT); + } + + if (flush == BTRFS_RESERVE_FLUSH_DATA) + async_work = &fs_info->async_data_reclaim_work; + else + async_work = &fs_info->async_reclaim_work; + + spin_lock(&space_info->lock); + used = btrfs_space_info_used(space_info, true); + + /* + * We don't want NO_FLUSH allocations to jump everybody, they can + * generally handle ENOSPC in a different way, so treat them the same as + * normal flushers when it comes to skipping pending tickets. + */ + if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH)) + pending_tickets = !list_empty(&space_info->tickets) || + !list_empty(&space_info->priority_tickets); + else + pending_tickets = !list_empty(&space_info->priority_tickets); + + /* + * Carry on if we have enough space (short-circuit) OR call + * can_overcommit() to ensure we can overcommit to continue. + */ + if (!pending_tickets && + ((used + orig_bytes <= space_info->total_bytes) || + btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) { + btrfs_space_info_update_bytes_may_use(fs_info, space_info, + orig_bytes); + ret = 0; + } + + /* + * Things are dire, we need to make a reservation so we don't abort. We + * will let this reservation go through as long as we have actual space + * left to allocate for the block. + */ + if (ret && unlikely(flush == BTRFS_RESERVE_FLUSH_EMERGENCY)) { + used = btrfs_space_info_used(space_info, false); + if (used + orig_bytes <= space_info->total_bytes) { + btrfs_space_info_update_bytes_may_use(fs_info, space_info, + orig_bytes); + ret = 0; + } + } + + /* + * If we couldn't make a reservation then setup our reservation ticket + * and kick the async worker if it's not already running. + * + * If we are a priority flusher then we just need to add our ticket to + * the list and we will do our own flushing further down. + */ + if (ret && can_ticket(flush)) { + ticket.bytes = orig_bytes; + ticket.error = 0; + space_info->reclaim_size += ticket.bytes; + init_waitqueue_head(&ticket.wait); + ticket.steal = can_steal(flush); + if (trace_btrfs_reserve_ticket_enabled()) + start_ns = ktime_get_ns(); + + if (flush == BTRFS_RESERVE_FLUSH_ALL || + flush == BTRFS_RESERVE_FLUSH_ALL_STEAL || + flush == BTRFS_RESERVE_FLUSH_DATA) { + list_add_tail(&ticket.list, &space_info->tickets); + if (!space_info->flush) { + /* + * We were forced to add a reserve ticket, so + * our preemptive flushing is unable to keep + * up. Clamp down on the threshold for the + * preemptive flushing in order to keep up with + * the workload. + */ + maybe_clamp_preempt(fs_info, space_info); + + space_info->flush = 1; + trace_btrfs_trigger_flush(fs_info, + space_info->flags, + orig_bytes, flush, + "enospc"); + queue_work(system_unbound_wq, async_work); + } + } else { + list_add_tail(&ticket.list, + &space_info->priority_tickets); + } + } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) { + /* + * We will do the space reservation dance during log replay, + * which means we won't have fs_info->fs_root set, so don't do + * the async reclaim as we will panic. + */ + if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) && + !work_busy(&fs_info->preempt_reclaim_work) && + need_preemptive_reclaim(fs_info, space_info)) { + trace_btrfs_trigger_flush(fs_info, space_info->flags, + orig_bytes, flush, "preempt"); + queue_work(system_unbound_wq, + &fs_info->preempt_reclaim_work); + } + } + spin_unlock(&space_info->lock); + if (!ret || !can_ticket(flush)) + return ret; + + return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns, + orig_bytes, flush); +} + +/* + * Try to reserve metadata bytes from the block_rsv's space. + * + * @fs_info: the filesystem + * @block_rsv: block_rsv we're allocating for + * @orig_bytes: number of bytes we want + * @flush: whether or not we can flush to make our reservation + * + * This will reserve orig_bytes number of bytes from the space info associated + * with the block_rsv. If there is not enough space it will make an attempt to + * flush out space to make room. It will do this by flushing delalloc if + * possible or committing the transaction. If flush is 0 then no attempts to + * regain reservations will be made and this will fail if there is not enough + * space already. + */ +int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info, + struct btrfs_block_rsv *block_rsv, + u64 orig_bytes, + enum btrfs_reserve_flush_enum flush) +{ + int ret; + + ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush); + if (ret == -ENOSPC) { + trace_btrfs_space_reservation(fs_info, "space_info:enospc", + block_rsv->space_info->flags, + orig_bytes, 1); + + if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) + btrfs_dump_space_info(fs_info, block_rsv->space_info, + orig_bytes, 0); + } + return ret; +} + +/* + * Try to reserve data bytes for an allocation. + * + * @fs_info: the filesystem + * @bytes: number of bytes we need + * @flush: how we are allowed to flush + * + * This will reserve bytes from the data space info. If there is not enough + * space then we will attempt to flush space as specified by flush. + */ +int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes, + enum btrfs_reserve_flush_enum flush) +{ + struct btrfs_space_info *data_sinfo = fs_info->data_sinfo; + int ret; + + ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA || + flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE || + flush == BTRFS_RESERVE_NO_FLUSH); + ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA); + + ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush); + if (ret == -ENOSPC) { + trace_btrfs_space_reservation(fs_info, "space_info:enospc", + data_sinfo->flags, bytes, 1); + if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) + btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0); + } + return ret; +} + +/* Dump all the space infos when we abort a transaction due to ENOSPC. */ +__cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info) +{ + struct btrfs_space_info *space_info; + + btrfs_info(fs_info, "dumping space info:"); + list_for_each_entry(space_info, &fs_info->space_info, list) { + spin_lock(&space_info->lock); + __btrfs_dump_space_info(fs_info, space_info); + spin_unlock(&space_info->lock); + } + dump_global_block_rsv(fs_info); +} + +/* + * Account the unused space of all the readonly block group in the space_info. + * takes mirrors into account. + */ +u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo) +{ + struct btrfs_block_group *block_group; + u64 free_bytes = 0; + int factor; + + /* It's df, we don't care if it's racy */ + if (list_empty(&sinfo->ro_bgs)) + return 0; + + spin_lock(&sinfo->lock); + list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) { + spin_lock(&block_group->lock); + + if (!block_group->ro) { + spin_unlock(&block_group->lock); + continue; + } + + factor = btrfs_bg_type_to_factor(block_group->flags); + free_bytes += (block_group->length - + block_group->used) * factor; + + spin_unlock(&block_group->lock); + } + spin_unlock(&sinfo->lock); + + return free_bytes; +} |