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btrfs-progs: docs: update sysfs descriptions
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[ci skip]

Issue: #374
Signed-off-by: David Sterba <dsterba@suse.com>
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kdave committed Jul 30, 2024
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57 changes: 51 additions & 6 deletions Documentation/ch-sysfs.rst
Original file line number Diff line number Diff line change
Expand Up @@ -49,11 +49,23 @@ clone_alignment
commit_stats
(RW, since: 6.0)

The performance statistics for btrfs transaction commit.
Mostly for debug purposes.
The performance statistics for btrfs transaction commit since the first
mount. Mostly for debugging purposes.

Writing into this file will reset the maximum commit duration
(*max_commit_ms*) to 0. The file looks like:

.. code-block:: none
commits 70649
last_commit_ms 2
max_commit_ms 131
total_commit_ms 170840
Writing into this file will reset the maximum commit duration to
the input value.
* *commits* - number of transaction commits since the first mount
* *last_commit_ms* - duration in miliseconds of the last commit
* *max_commit_ms* - maximum time a transaction commit took since first mount or last reset
* *total_commit_ms* - sum of all transaction commit times

exclusive_operation
(RO, since: 5.10)
Expand Down Expand Up @@ -103,6 +115,12 @@ sectorsize
Shows the sectorsize of the mounted filesystem.


temp_fsid
(RO, since 6.7)

Indicate that this filesystem got assigned a temporary FSID at mount time,
making possible to mount devices with the same FSID.

Files and directories in :file:`/sys/fs/btrfs/<UUID>/allocations` directory are:

global_rsv_reserved
Expand Down Expand Up @@ -130,18 +148,45 @@ bg_reclaim_threshold
permanently unusable space) to reclaim the block group.
Can be used on regular or zoned devices.

bytes_*
(RO)

Values of the corresponding data structures for the given block group
type and profile.

chunk_size
(RW, since: 6.0)

Shows the chunk size. Can be changed for data and metadata.
Cannot be set for zoned devices.

size_classes
(RO, since: 6.3)

Numbers of block groups of a given classes based on heuristics that
measure extent length, age and fragmentation.

.. code-block:: none
none 136
small 374
medium 282
large 93
Files in :file:`/sys/fs/btrfs/<UUID>/devinfo/<DEVID>` directory are:

error_stats:
(RO, since: 5.14)

Shows all the history error numbers of the device.
Shows device stats of this device, same as :command:`btrfs device stats` (:doc:`btrfs-device`).

.. code-block:: none
write_errs 0
read_errs 0
flush_errs 0
corruption_errs 0
generation_errs 0
fsid:
(RO, since: 5.17)
Expand Down Expand Up @@ -171,7 +216,7 @@ scrub_speed_max
(RW, since: 5.14)

Shows the scrub speed limit for this device. The unit is Bytes/s.
0 means no limit.
0 means no limit. The value can be set but is not persisent.

writeable
(RO, since: 5.6)
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