This is a repost of an old patch (~2017). At the time it din't received
any feedback. I repost it hoping that it still be interesting.
This patch is the kernel related one; another one related to the
btrfs-progs is send separately.
v2:
- Remove the goto from copy_chunk_info()
V1:
- First issue
----
This patch set creates a new ioctl BTRFS_IOC_GET_CHUNK_INFO.
The aim is to replace the BTRFS_IOC_TREE_SEARCH ioctl
used by "btrfs fi usage" to obtain information about the
chunks/block groups.
The problems in using the BTRFS_IOC_TREE_SEARCH is that it access
the very low data structure of BTRFS. This means:
1) this would be complicated a possible change of the disk format
2) it requires the root privileges
The BTRFS_IOC_GET_CHUNK_INFO ioctl can be called even from a not root
user: I think that the data exposed are not sensibile data.
These patches allow to use "btrfs fi usage" without root privileges.
before:
-------------------------------------------
$ btrfs fi us /
WARNING: cannot read detailed chunk info, per-device usage will not be shown, run as root
Overall:
Device size: 100.00GiB
Device allocated: 26.03GiB
Device unallocated: 73.97GiB
Device missing: 0.00B
Used: 17.12GiB
Free (estimated): 80.42GiB (min: 80.42GiB)
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 53.12MiB (used: 0.00B)
Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
after:
-----------------------------------------------
$ ./btrfs fi us /
Overall:
Device size: 100.00GiB
Device allocated: 26.03GiB
Device unallocated: 73.97GiB
Device missing: 0.00B
Used: 17.12GiB
Free (estimated): 80.42GiB (min: 80.42GiB)
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 53.12MiB (used: 0.00B)
Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
/dev/sdd3 23.00GiB
Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
/dev/sdd3 3.00GiB
System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
/dev/sdd3 32.00MiB
Unallocated:
/dev/sdd3 73.97GiB
Comments are welcome
BR
G.Baroncelli
--
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