From 18bb8bbf13c1839b43c9e09e76d397b753989af2 Mon Sep 17 00:00:00 2001 From: Johannes Thumshirn Date: Mon, 19 Apr 2021 16:41:02 +0900 Subject: btrfs: zoned: automatically reclaim zones When a file gets deleted on a zoned file system, the space freed is not returned back into the block group's free space, but is migrated to zone_unusable. As this zone_unusable space is behind the current write pointer it is not possible to use it for new allocations. In the current implementation a zone is reset once all of the block group's space is accounted as zone unusable. This behaviour can lead to premature ENOSPC errors on a busy file system. Instead of only reclaiming the zone once it is completely unusable, kick off a reclaim job once the amount of unusable bytes exceeds a user configurable threshold between 51% and 100%. It can be set per mounted filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75% by default. Similar to reclaiming unused block groups, these dirty block groups are added to a to_reclaim list and then on a transaction commit, the reclaim process is triggered but after we deleted unused block groups, which will free space for the relocation process. Reviewed-by: Filipe Manana Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 101 ++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/block-group.h | 3 ++ fs/btrfs/ctree.h | 5 +++ fs/btrfs/disk-io.c | 13 ++++++ fs/btrfs/free-space-cache.c | 9 +++- fs/btrfs/sysfs.c | 35 +++++++++++++++ fs/btrfs/volumes.c | 2 +- fs/btrfs/volumes.h | 1 + fs/btrfs/zoned.h | 6 +++ 9 files changed, 173 insertions(+), 2 deletions(-) (limited to 'fs/btrfs') diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index bbb5a6e170c7..aa57bdc8fc89 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1485,6 +1485,97 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) spin_unlock(&fs_info->unused_bgs_lock); } +void btrfs_reclaim_bgs_work(struct work_struct *work) +{ + struct btrfs_fs_info *fs_info = + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); + struct btrfs_block_group *bg; + struct btrfs_space_info *space_info; + int ret; + + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) + return; + + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) + return; + + mutex_lock(&fs_info->reclaim_bgs_lock); + spin_lock(&fs_info->unused_bgs_lock); + while (!list_empty(&fs_info->reclaim_bgs)) { + bg = list_first_entry(&fs_info->reclaim_bgs, + struct btrfs_block_group, + bg_list); + list_del_init(&bg->bg_list); + + space_info = bg->space_info; + spin_unlock(&fs_info->unused_bgs_lock); + + /* Don't race with allocators so take the groups_sem */ + down_write(&space_info->groups_sem); + + spin_lock(&bg->lock); + if (bg->reserved || bg->pinned || bg->ro) { + /* + * We want to bail if we made new allocations or have + * outstanding allocations in this block group. We do + * the ro check in case balance is currently acting on + * this block group. + */ + spin_unlock(&bg->lock); + up_write(&space_info->groups_sem); + goto next; + } + spin_unlock(&bg->lock); + + /* Get out fast, in case we're unmounting the filesystem */ + if (btrfs_fs_closing(fs_info)) { + up_write(&space_info->groups_sem); + goto next; + } + + ret = inc_block_group_ro(bg, 0); + up_write(&space_info->groups_sem); + if (ret < 0) + goto next; + + btrfs_info(fs_info, "reclaiming chunk %llu with %llu%% used", + bg->start, div_u64(bg->used * 100, bg->length)); + trace_btrfs_reclaim_block_group(bg); + ret = btrfs_relocate_chunk(fs_info, bg->start); + if (ret) + btrfs_err(fs_info, "error relocating chunk %llu", + bg->start); + +next: + btrfs_put_block_group(bg); + spin_lock(&fs_info->unused_bgs_lock); + } + spin_unlock(&fs_info->unused_bgs_lock); + mutex_unlock(&fs_info->reclaim_bgs_lock); + btrfs_exclop_finish(fs_info); +} + +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info) +{ + spin_lock(&fs_info->unused_bgs_lock); + if (!list_empty(&fs_info->reclaim_bgs)) + queue_work(system_unbound_wq, &fs_info->reclaim_bgs_work); + spin_unlock(&fs_info->unused_bgs_lock); +} + +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg) +{ + struct btrfs_fs_info *fs_info = bg->fs_info; + + spin_lock(&fs_info->unused_bgs_lock); + if (list_empty(&bg->bg_list)) { + btrfs_get_block_group(bg); + trace_btrfs_add_reclaim_block_group(bg); + list_add_tail(&bg->bg_list, &fs_info->reclaim_bgs); + } + spin_unlock(&fs_info->unused_bgs_lock); +} + static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key, struct btrfs_path *path) { @@ -3446,6 +3537,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) } spin_unlock(&info->unused_bgs_lock); + spin_lock(&info->unused_bgs_lock); + while (!list_empty(&info->reclaim_bgs)) { + block_group = list_first_entry(&info->reclaim_bgs, + struct btrfs_block_group, + bg_list); + list_del_init(&block_group->bg_list); + btrfs_put_block_group(block_group); + } + spin_unlock(&info->unused_bgs_lock); + spin_lock(&info->block_group_cache_lock); while ((n = rb_last(&info->block_group_cache_tree)) != NULL) { block_group = rb_entry(n, struct btrfs_block_group, diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h index 3ecc3372a5ce..7b927425dc71 100644 --- a/fs/btrfs/block-group.h +++ b/fs/btrfs/block-group.h @@ -264,6 +264,9 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, u64 group_start, struct extent_map *em); void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info); void btrfs_mark_bg_unused(struct btrfs_block_group *bg); +void btrfs_reclaim_bgs_work(struct work_struct *work); +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info); +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg); int btrfs_read_block_groups(struct btrfs_fs_info *info); int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used, u64 type, u64 chunk_offset, u64 size); diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 1f0005efdada..278e0cbc9a98 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -960,6 +960,11 @@ struct btrfs_fs_info { struct work_struct async_data_reclaim_work; struct work_struct preempt_reclaim_work; + /* Reclaim partially filled block groups in the background */ + struct work_struct reclaim_bgs_work; + struct list_head reclaim_bgs; + int bg_reclaim_threshold; + spinlock_t unused_bgs_lock; struct list_head unused_bgs; struct mutex unused_bg_unpin_mutex; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index e52b89ad0a61..c9a3036c23bf 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1898,6 +1898,13 @@ static int cleaner_kthread(void *arg) * unused block groups. */ btrfs_delete_unused_bgs(fs_info); + + /* + * Reclaim block groups in the reclaim_bgs list after we deleted + * all unused block_groups. This possibly gives us some more free + * space. + */ + btrfs_reclaim_bgs(fs_info); sleep: clear_and_wake_up_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags); if (kthread_should_park()) @@ -2886,6 +2893,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) INIT_LIST_HEAD(&fs_info->space_info); INIT_LIST_HEAD(&fs_info->tree_mod_seq_list); INIT_LIST_HEAD(&fs_info->unused_bgs); + INIT_LIST_HEAD(&fs_info->reclaim_bgs); #ifdef CONFIG_BTRFS_DEBUG INIT_LIST_HEAD(&fs_info->allocated_roots); INIT_LIST_HEAD(&fs_info->allocated_ebs); @@ -2974,6 +2982,9 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) fs_info->swapfile_pins = RB_ROOT; fs_info->send_in_progress = 0; + + fs_info->bg_reclaim_threshold = BTRFS_DEFAULT_RECLAIM_THRESH; + INIT_WORK(&fs_info->reclaim_bgs_work, btrfs_reclaim_bgs_work); } static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block *sb) @@ -4332,6 +4343,8 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) cancel_work_sync(&fs_info->async_data_reclaim_work); cancel_work_sync(&fs_info->preempt_reclaim_work); + cancel_work_sync(&fs_info->reclaim_bgs_work); + /* Cancel or finish ongoing discard work */ btrfs_discard_cleanup(fs_info); diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 9988decd5717..e54466fc101f 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -11,6 +11,7 @@ #include #include #include +#include "misc.h" #include "ctree.h" #include "free-space-cache.h" #include "transaction.h" @@ -2539,6 +2540,7 @@ out: static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, u64 bytenr, u64 size, bool used) { + struct btrfs_fs_info *fs_info = block_group->fs_info; struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; u64 offset = bytenr - block_group->start; u64 to_free, to_unusable; @@ -2569,8 +2571,13 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, } /* All the region is now unusable. Mark it as unused and reclaim */ - if (block_group->zone_unusable == block_group->length) + if (block_group->zone_unusable == block_group->length) { btrfs_mark_bg_unused(block_group); + } else if (block_group->zone_unusable >= + div_factor_fine(block_group->length, + fs_info->bg_reclaim_threshold)) { + btrfs_mark_bg_to_reclaim(block_group); + } return 0; } diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index a99d1f415a7f..436ac7b4b334 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -980,6 +980,40 @@ static ssize_t btrfs_read_policy_store(struct kobject *kobj, } BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store); +static ssize_t btrfs_bg_reclaim_threshold_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + ssize_t ret; + + ret = scnprintf(buf, PAGE_SIZE, "%d\n", fs_info->bg_reclaim_threshold); + + return ret; +} + +static ssize_t btrfs_bg_reclaim_threshold_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + int thresh; + int ret; + + ret = kstrtoint(buf, 10, &thresh); + if (ret) + return ret; + + if (thresh <= 50 || thresh > 100) + return -EINVAL; + + fs_info->bg_reclaim_threshold = thresh; + + return len; +} +BTRFS_ATTR_RW(, bg_reclaim_threshold, btrfs_bg_reclaim_threshold_show, + btrfs_bg_reclaim_threshold_store); + static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, label), BTRFS_ATTR_PTR(, nodesize), @@ -991,6 +1025,7 @@ static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, exclusive_operation), BTRFS_ATTR_PTR(, generation), BTRFS_ATTR_PTR(, read_policy), + BTRFS_ATTR_PTR(, bg_reclaim_threshold), NULL, }; diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index c3afea264a3f..77cdb75acc15 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3098,7 +3098,7 @@ out: return ret; } -static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) { struct btrfs_root *root = fs_info->chunk_root; struct btrfs_trans_handle *trans; diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index d4c3e0dd32b8..9c0d84e5ec06 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -484,6 +484,7 @@ void btrfs_describe_block_groups(u64 flags, char *buf, u32 size_buf); int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info); int btrfs_recover_balance(struct btrfs_fs_info *fs_info); int btrfs_pause_balance(struct btrfs_fs_info *fs_info); +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset); int btrfs_cancel_balance(struct btrfs_fs_info *fs_info); int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info); int btrfs_uuid_scan_kthread(void *data); diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h index 61e969652fe1..5e41a74a9cb2 100644 --- a/fs/btrfs/zoned.h +++ b/fs/btrfs/zoned.h @@ -9,6 +9,12 @@ #include "disk-io.h" #include "block-group.h" +/* + * Block groups with more than this value (percents) of unusable space will be + * scheduled for background reclaim. + */ +#define BTRFS_DEFAULT_RECLAIM_THRESH 75 + struct btrfs_zoned_device_info { /* * Number of zones, zone size and types of zones if bdev is a -- cgit v1.2.3