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 <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index bbb5a6e..aa57bdc 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 3ecc337..7b92742 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 1f0005e..278e0cb 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 e52b89a..c9a3036 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 9988dec..e54466f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -11,6 +11,7 @@
#include <linux/ratelimit.h>
#include <linux/error-injection.h>
#include <linux/sched/mm.h>
+#include "misc.h"
#include "ctree.h"
#include "free-space-cache.h"
#include "transaction.h"
@@ -2539,6 +2540,7 @@ int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
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 a99d1f4..436ac7b4 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 c3afea2..77cdb75 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3098,7 +3098,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
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 d4c3e0d..9c0d84e 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 61e9696..5e41a74 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
