@@ -1485,6 +1485,92 @@ 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 = 0;
+
+ 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 want to 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);
+
+ ret = inc_block_group_ro(bg, 0);
+ up_write(&space_info->groups_sem);
+ if (ret < 0) {
+ ret = 0;
+ goto next;
+ }
+
+ btrfs_info(fs_info, "reclaiming chunk %llu", bg->start);
+ 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 +3532,16 @@ 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,
@@ -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);
@@ -954,10 +954,14 @@ struct btrfs_fs_info {
struct work_struct async_data_reclaim_work;
struct work_struct preempt_reclaim_work;
+ /* Used to reclaim data space in the background */
+ struct work_struct reclaim_bgs_work;
+
spinlock_t unused_bgs_lock;
struct list_head unused_bgs;
struct mutex unused_bg_unpin_mutex;
struct mutex reclaim_bgs_lock;
+ struct list_head reclaim_bgs;
/* Cached block sizes */
u32 nodesize;
@@ -998,6 +1002,8 @@ struct btrfs_fs_info {
spinlock_t treelog_bg_lock;
u64 treelog_bg;
+ int bg_reclaim_threshold;
+
#ifdef CONFIG_BTRFS_FS_REF_VERIFY
spinlock_t ref_verify_lock;
struct rb_root block_tree;
@@ -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 = 75;
+ 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);
@@ -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;
}
@@ -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,
};
@@ -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;
@@ -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);
@@ -1903,6 +1903,18 @@ DEFINE_EVENT(btrfs__block_group, btrfs_add_unused_block_group,
TP_ARGS(bg_cache)
);
+DEFINE_EVENT(btrfs__block_group, btrfs_add_reclaim_block_group,
+ TP_PROTO(const struct btrfs_block_group *bg_cache),
+
+ TP_ARGS(bg_cache)
+);
+
+DEFINE_EVENT(btrfs__block_group, btrfs_reclaim_block_group,
+ TP_PROTO(const struct btrfs_block_group *bg_cache),
+
+ TP_ARGS(bg_cache)
+);
+
DEFINE_EVENT(btrfs__block_group, btrfs_skip_unused_block_group,
TP_PROTO(const struct btrfs_block_group *bg_cache),
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% per 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. Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> --- fs/btrfs/block-group.c | 96 ++++++++++++++++++++++++++++++++++++ fs/btrfs/block-group.h | 3 ++ fs/btrfs/ctree.h | 6 +++ 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 + include/trace/events/btrfs.h | 12 +++++ 9 files changed, 175 insertions(+), 2 deletions(-)