Commit 140a8ff7 authored by Ioannis Angelakopoulos's avatar Ioannis Angelakopoulos Committed by David Sterba
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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: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarIoannis Angelakopoulos <iangelak@fb.com>
[ update changelog ]
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent e55958c8

fs/btrfs/sysfs.c

+43 −1
Original line number Diff line number Diff line
@@ -991,6 +991,48 @@ static ssize_t btrfs_sectorsize_show(struct kobject *kobj, 


BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);



static ssize_t btrfs_commit_stats_show(struct kobject *kobj,

				       struct kobj_attribute *a, char *buf)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);



	return sysfs_emit(buf,

		"commits %llu\n"

		"last_commit_ms %llu\n"

		"max_commit_ms %llu\n"

		"total_commit_ms %llu\n",

		fs_info->commit_stats.commit_count,

		div_u64(fs_info->commit_stats.last_commit_dur, NSEC_PER_MSEC),

		div_u64(fs_info->commit_stats.max_commit_dur, NSEC_PER_MSEC),

		div_u64(fs_info->commit_stats.total_commit_dur, NSEC_PER_MSEC));

}



static ssize_t btrfs_commit_stats_store(struct kobject *kobj,

					struct kobj_attribute *a,

					const char *buf, size_t len)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);

	unsigned long val;

	int ret;



	if (!fs_info)

		return -EPERM;



	if (!capable(CAP_SYS_RESOURCE))

		return -EPERM;



	ret = kstrtoul(buf, 10, &val);

	if (ret)

		return ret;

	if (val)

		return -EINVAL;



	WRITE_ONCE(fs_info->commit_stats.max_commit_dur, 0);



	return len;

}

BTRFS_ATTR_RW(, commit_stats, btrfs_commit_stats_show, btrfs_commit_stats_store);



static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,

				struct kobj_attribute *a, char *buf)

{
@@ -1230,6 +1272,7 @@ static const struct attribute *btrfs_attrs[] = { 
	BTRFS_ATTR_PTR(, generation),

	BTRFS_ATTR_PTR(, read_policy),

	BTRFS_ATTR_PTR(, bg_reclaim_threshold),

	BTRFS_ATTR_PTR(, commit_stats),

	NULL,

};
@@ -2236,4 +2279,3 @@ void __cold btrfs_exit_sysfs(void) 
#endif

	kset_unregister(btrfs_kset);

}