Re: Unable to mount multiple subvolumes of a single disk

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

Hi Anand

On 15/09/14 17:09, Anand Jain wrote:
>
> Sam,
>
>   Thanks for reporting. Can you apply the following diff
>   on top of 3.17rc5 and check if it helps.

The patch fixes the issue, although it took a little tweaking to get it 
to apply cleanly.

> -------
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index e9676a4..1224b61 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -533,7 +533,7 @@ static noinline int device_list_add(const char *path,
>                   * the btrfs dev scan cli, after FS has been mounted.
>                   */
>                  if (fs_devices->opened) {
> -                       return -EBUSY;
> +                       goto out;
>                  } else {
>                          /*
>                           * That is if the FS is _not_ mounted and if you
> @@ -566,6 +566,7 @@ static noinline int device_list_add(const char *path,
>          if (!fs_devices->opened)
>                  device->generation = found_transid;
>
> +out:
>          *fs_devices_ret = fs_devices;
>
>          return ret;
> -------
>
>
>
>
> Anand
>
>
>
> On 15/09/2014 23:54, Chris Mason wrote:
>> On 09/15/2014 11:13 AM, Sam Thursfield wro:
>>> 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://urldefense.proofpoint.com/v1/url?u=https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id%3Db96de000bc8bc9688b3a2abea4332bd57648a49f&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=6%2FL0lzzDhu0Y1hL9xm%2BQyA%3D%3D%0A&m=qVtp3yxxUd8uElAkp118K4Bd0oZfeUOC%2BKUy3e6rRlA%3D%0A&s=0d2623956de100adc1185d2b75e9114384572b88c0330e74924baa1a2bce8d02
>>>
>>>
>>>
>>> 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.
>>
>> Anand Jain is working on this in a separate thread.  I'll make sure the
>> fix goes into the next rc, thanks for all the time spent bisecting.
>>
>> -chris
>>
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-- 
Sam Thursfield, Codethink Ltd.
Office telephone: +44 161 236 5575