On 11/19/19 8:37 PM, David Sterba wrote:
On Tue, Nov 19, 2019 at 02:44:10PM +0800, Anand Jain wrote:
On 11/18/19 11:45 PM, David Sterba wrote:
On Mon, Nov 18, 2019 at 04:46:41PM +0800, Anand Jain wrote:
Mostly cleanups patches.
Patches 1-7 are renames, code moves patches and there are no
functional changes.
Patch 8 drops unused argument in the function btrfs_sysfs_add_fsid().
Patch 9 merges two small functions which is an extension of the other.
Patches 10,11 and 13 removes unnecessary features in the functions,
originally it was planned to provide sysfs attributes for the scanned
and unmounted devices, as in the un-merged patch in the mailing list [1]
[1] [PATCH] btrfs: Introduce device pool sysfs attributes
We want something like that,
Oh.
Ok then I shall relook at these patches with a mind that we might
introduce the sysfs for non mounted devices.
I don't recall all the past discussions,
No worries. There wasn't any discussions on this specific topic.
There were several patchsets sent adding device information exports, and
commented, eg.
https://lore.kernel.org/linux-btrfs/1423439785-10260-1-git-send-email-anand.jain@xxxxxxxxxx/t/#u
https://lore.kernel.org/linux-btrfs/1416814173-16945-1-git-send-email-anand.jain@xxxxxxxxxx/t/#u
and maybe followups.
Ah I missed those reply as I checked the much later patch.
https://lore.kernel.org/linux-btrfs/1ac04f0d-f33e-8161-4688-eebb42d51a54@xxxxxxxxxx/
but a separate directory for all the new sysfs files should be
introduced. Extending the existing /devices/ that contains just the
sysfs device like should stay as is.
/sys/fs/btrfs/UUID/
devinfo/
1/
uuid
state
...
2/
...
umm how about..
$ btrfs fi show
Label: none uuid: 52ad6beb-524d-4cd8-8979-0890d0b74314
Total devices 4 FS bytes used 384.00KiB
devid 1 size 2.93GiB used 368.00MiB path /dev/sdb
devid 2 size 2.93GiB used 368.00MiB path /dev/sdc
devid 3 size 2.93GiB used 368.00MiB path /dev/sdd
devid 4 size 2.93GiB used 368.00MiB path /dev/sde
# ls -l /sys/fs/btrfs/52ad6beb-524d-4cd8-8979-0890d0b74314/devices/
total 0
drwxr-xr-x 2 root root 0 Nov 19 14:39 1_sdb
Something like that has been suggested in the patchsets, I disagree with
the device id and name being glued together. The sysfs files should
server scripting, the enumeration should be straightforward and not
requiring parsing of the filenames.
Oh right point.
drwxr-xr-x 2 root root 0 Nov 19 14:39 2_sdc
drwxr-xr-x 2 root root 0 Nov 19 14:39 3_sdd
drwxr-xr-x 2 root root 0 Nov 19 14:39 4_sde
lrwxrwxrwx 1 root root 0 Nov 19 14:39 sdb ->
../../../../devices/pci0000:00/0000:00:0d.0/ata2/host1/target1:0:0/1:0:0:0/block/sdb
lrwxrwxrwx 1 root root 0 Nov 19 14:39 sdc ->
../../../../devices/pci0000:00/0000:00:0d.0/ata3/host2/target2:0:0/2:0:0:0/block/sdc
lrwxrwxrwx 1 root root 0 Nov 19 14:39 sdd ->
../../../../devices/pci0000:00/0000:00:0d.0/ata4/host3/target3:0:0/3:0:0:0/block/sdd
lrwxrwxrwx 1 root root 0 Nov 19 14:39 sde ->
../../../../devices/pci0000:00/0000:00:0d.0/ata5/host4/target4:0:0/4:0:0:0/block/sde
If you want to put the directories under /sys/fs/btrfs/UUID/deevices/
then it's probably ok as long as there device node links are plain files
and the directories represent the ids. But just the ids, the actual
device name depends on the assignment by block layer. This is not
persistent.
So two possible layouts:
fs/UUID/devices
sda
sdb
sdc
1/
...
2/
...
3/
...
Will use this layout.
Thanks, Anand
Or the one suggested before, where devices by id are in a separate
directory. This is modelled after /dev/disk/by-id and the like, but I
don't think we need to make it granular like that.
