summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/space-info.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/btrfs/space-info.c')
-rw-r--r--fs/btrfs/space-info.c1853
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;
+}