btrfs: sysfs: show temp_fsid feature
This adds sysfs objects to indicate temp_fsid feature support and
its status.
/sys/fs/btrfs/features/temp_fsid
/sys/fs/btrfs/<UUID>/temp_fsid
For example:
Consider two cloned and mounted devices.
$ blkid /dev/sdc[1-2]
/dev/sdc1: UUID="
509ad44b-ad2a-4a8a-bc8d-
fe69db7220d5" ..
/dev/sdc2: UUID="
509ad44b-ad2a-4a8a-bc8d-
fe69db7220d5" ..
One gets actual fsid, and the other gets the temp_fsid when
mounted.
$ btrfs filesystem show -m
Label: none uuid:
509ad44b-ad2a-4a8a-bc8d-
fe69db7220d5
Total devices 1 FS bytes used 54.14MiB
devid 1 size 300.00MiB used 144.00MiB path /dev/sdc1
Label: none uuid:
33bad74e-c91b-43a5-aef8-
b3cab97ae63a
Total devices 1 FS bytes used 54.14MiB
devid 1 size 300.00MiB used 144.00MiB path /dev/sdc2
Their sysfs as below.
$ cat /sys/fs/btrfs/features/temp_fsid
0
$ cat /sys/fs/btrfs/
509ad44b-ad2a-4a8a-bc8d-
fe69db7220d5/temp_fsid
0
$ cat /sys/fs/btrfs/
33bad74e-c91b-43a5-aef8-
b3cab97ae63a/temp_fsid
1
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>