Re: Unable to mount multiple subvolumes of a single disk

[Sam Thursfield <sam.thursfield@codethink.co.uk>]

On 15/09/14 17:42, Anand Jain wrote:
>
>   Logs from Sam, tells the problem clearly.  mount is using
>   /dev/sda, but mount error message and kernel is using /dev/vda.
>
> ----------------------
> $ mount /dev/sda /home -t btrfs -o subvol=/state/home,defaults,rw,noatime
> mount: /dev/vda is already mounted or /home busy
>         /dev/vda is already mounted on /

Sorry for the confusion here. I typed in the shell commands into the log 
manually and obviously put /dev/sda when I meant /dev/vda.

I've retested with /dev/vda and the same error occurs.

> On 15/09/2014 23:13, Sam Thursfield wrote:
>> Hi!
>>
>> I'm having an issue with the 3.17rc5 kernel which prevents having
>> multiple subvolumes of the same disk mounted.
>>
>> I'm not sure exactly the cause. I thought it might be because in my
>> system the root file system is itself a subvolume of the disk I'm trying
>> to mount. But if I create a second disk image with two subvolumes, the
>> same thing occurs -- I can only mount one of them at a time.
>>
>> I've attached the output of a few commands, please let me know if you
>> want more info (I'm not subscribed to the list, please keep me in To:).
>>
>> We've bisected and found that the exact commit that changed the
>> behaviour is this one:
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b96de000bc8bc9688b3a2abea4332bd57648a49f
>>
>>
>>
>> I'm afraid I'm not familiar with the Btrfs code base and so I don't
>> understand the exact meaning of the comments in that commit.
>>
>> Thanks
>> Sam
>>


-- 
Sam Thursfield, Codethink Ltd.
Office telephone: +44 161 236 5575