path: root/include/trace
diff options
authorJohannes Thumshirn <>2021-04-19 16:41:02 +0900
committerDavid Sterba <>2021-04-20 20:46:31 +0200
commit18bb8bbf13c1839b43c9e09e76d397b753989af2 (patch)
tree129cbdd4389bbaa1dc598da8a40138729f26f77b /include/trace
parentf33720657d29d6b7282dd2e5e8634e0a39ad372e (diff)
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 <>
Diffstat (limited to 'include/trace')
1 files changed, 12 insertions, 0 deletions
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index 0551ea65374f..a41dd8a0c730 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -1903,6 +1903,18 @@ DEFINE_EVENT(btrfs__block_group, btrfs_add_unused_block_group,
+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),