btrfs: sysfs: export commit stats

Export commit stats in file

  /sys/fs/btrfs/UUID/commit_stats

with example output like:

  commits 123
  last_commit_ms 11
  max_commit_ms 150
  total_commit_ms 2000

The values are in one file so reading them at a single time will give a
more consistent view. The stats are internally tracked in nanoseconds so
the cumulative values should not suffer from rounding errors.

Writing 0 to the file 'commit_stats' will reset max_commit_ms.
Initial values are set at first mount of the filesystem.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Ioannis Angelakopoulos <[email protected]>
[ update changelog ]
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

0 files changed, 0 insertions, 0 deletions