Mount doesn't show subvol option for btrfs

Mount doesn't show subvol option for btrfs

[james harvey]

Not sure if this could be a linux-unionfs (btrfs) bug instead...

On arch, /etc/fstab includes:

/dev/sda1   /.snapshots   btrfs
rw,noatime,compress=lzo,ssd,discard,space_cache,subvol=.snapshots   0
 0

But mount includes:

/dev/sda1 on /.snapshots type btrfs
(rw,noatime,compress=lzo,ssd,discard,space_cache)

The subvol option isn't reported in mount.

This happens on all of my btrfs mounts, not just .snapshots.

Re: Mount doesn't show subvol option for btrfs

[Karel Zak]

On Sun, Jun 14, 2015 at 04:50:09PM -0400, james harvey wrote:
> Not sure if this could be a linux-unionfs (btrfs) bug instead...
> 
> On arch, /etc/fstab includes:
> 
> /dev/sda1   /.snapshots   btrfs
> rw,noatime,compress=lzo,ssd,discard,space_cache,subvol=.snapshots   0
>  0
> 
> But mount includes:
> 
> /dev/sda1 on /.snapshots type btrfs
> (rw,noatime,compress=lzo,ssd,discard,space_cache)
> 
> The subvol option isn't reported in mount.


 mount(8) uses /proc/self/mountinfo as source, do you see the subvol=
 mount option there?

 (well, I guess you have system without mtab and recent util-linux.)

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: Mount doesn't show subvol option for btrfs

[Tom Yan]

[tom@localhost ~]$ mount | grep sda2
/dev/sda2 on / type btrfs (rw,relatime,ssd,space_cache)

[tom@localhost ~]$ cat /proc/self/mountinfo | grep sda2
19 0 0:17 /arch / rw,relatime shared:1 - btrfs /dev/sda2 rw,ssd,space_cache

[tom@localhost ~]$ findmnt /dev/sda2
TARGET SOURCE           FSTYPE OPTIONS
/      /dev/sda2[/arch] btrfs  rw,relatime,ssd,space_cache

It won't be shown as a mount option.

On 15 June 2015 at 19:28, Karel Zak <kzak@redhat.com> wrote:
> On Sun, Jun 14, 2015 at 04:50:09PM -0400, james harvey wrote:
>> Not sure if this could be a linux-unionfs (btrfs) bug instead...
>>
>> On arch, /etc/fstab includes:
>>
>> /dev/sda1   /.snapshots   btrfs
>> rw,noatime,compress=lzo,ssd,discard,space_cache,subvol=.snapshots   0
>>  0
>>
>> But mount includes:
>>
>> /dev/sda1 on /.snapshots type btrfs
>> (rw,noatime,compress=lzo,ssd,discard,space_cache)
>>
>> The subvol option isn't reported in mount.
>
>
>  mount(8) uses /proc/self/mountinfo as source, do you see the subvol=
>  mount option there?
>
>  (well, I guess you have system without mtab and recent util-linux.)
>
>     Karel
>
> --
>  Karel Zak  <kzak@redhat.com>
>  http://karelzak.blogspot.com
> --
> To unsubscribe from this list: send the line "unsubscribe util-linux" in
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Re: Mount doesn't show subvol option for btrfs

[Karel Zak]

On Tue, Jun 16, 2015 at 01:42:54PM +0800, Tom Yan wrote:
> [tom@localhost ~]$ mount | grep sda2
> /dev/sda2 on / type btrfs (rw,relatime,ssd,space_cache)
> 
> [tom@localhost ~]$ cat /proc/self/mountinfo | grep sda2
> 19 0 0:17 /arch / rw,relatime shared:1 - btrfs /dev/sda2 rw,ssd,space_cache
> 
> [tom@localhost ~]$ findmnt /dev/sda2
> TARGET SOURCE           FSTYPE OPTIONS
> /      /dev/sda2[/arch] btrfs  rw,relatime,ssd,space_cache
> 
> It won't be shown as a mount option.

Ah, good point. Yes, the subvolume directory is interpreted as FS
mount root, I forgot this btrfs feature.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com