Print the total zone_unusable size in the summary for 'fi usage' for a
filesystem in zoned mode. It's a sum of all the zone_unusable values
from 'fi df'. Per-device stats are not implemented and would need more
complicated calculations from raw data, kernel does not export that (but
it could).
As of 5.12, the zone_unusable is stored only in memory so we'd have to
map raw block device zones to the block groups and the live extents in
the associated block groups to get the exact numbers.
Example:
# btrfs fi usage /mnt
Overall:
Device size: 2.00GiB
Device allocated: 768.00MiB
Device unallocated: 1.25GiB
Device missing: 0.00B
Device zone unusable: 320.00KiB
Used: 128.00KiB
Free (estimated): 1.50GiB (min: 1.50GiB)
Free (statfs, df): 1.50GiB
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 3.25MiB (used: 32.00KiB)
Multiple profiles: no
Data,single: Size:256.00MiB, Used:0.00B (0.00%)
/dev/nullb0 256.00MiB
Metadata,single: Size:256.00MiB, Used:112.00KiB (0.04%)
/dev/nullb0 256.00MiB
System,single: Size:256.00MiB, Used:16.00KiB (0.01%)
/dev/nullb0 256.00MiB
Unallocated:
/dev/nullb0 1.25GiB
# btrfs fi df
Data, single: total=256.00MiB, used=0.00B, zone_unusable=0.00B
System, single: total=256.00MiB, used=16.00KiB, zone_unusable=160.00KiB
Metadata, single: total=256.00MiB, used=112.00KiB, zone_unusable=160.00KiB
GlobalReserve, single: total=3.25MiB, used=32.00KiB
Signed-off-by: David Sterba <dsterba@suse.com>
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