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| author | Johannes Thumshirn <johannes.thumshirn@wdc.com> | 2021-04-19 10:41:02 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2021-04-20 21:46:31 +0300 |
| commit | 18bb8bbf13c1839b43c9e09e76d397b753989af2 (patch) | |
| tree | 129cbdd4389bbaa1dc598da8a40138729f26f77b /fs/btrfs/zoned.h | |
| parent | f33720657d29d6b7282dd2e5e8634e0a39ad372e (diff) | |
| download | linux-18bb8bbf13c1839b43c9e09e76d397b753989af2.tar.xz | |
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>
Diffstat (limited to 'fs/btrfs/zoned.h')
| -rw-r--r-- | fs/btrfs/zoned.h | 6 |
1 files changed, 6 insertions, 0 deletions
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 |