[libvirt] [PATCH 1/3] Revert "storage: For FS pool check for properly formatted target volume"

[John Ferlan]

On 01/12/2017 09:41 AM, Peter Krempa wrote:
> On Thu, Jan 12, 2017 at 09:36:01 -0500, John Ferlan wrote:
>>
>>
>> On 01/12/2017 09:24 AM, Peter Krempa wrote:
>>> The check does not work properly (crashes) with netfs filesystems and
>>> also checking that a device is not empty when attempting to mount a
>>> filesystem is not very usefull since the mount will fail anyways.
>>>
>>> As the code would improve only a very minor corner case I don't really
>>> see a reason to have this code at all.
>>>
>>> This code would also fail if libvirt is compiled without support for
>>> blkid and without parted.
>>>
>>> This reverts commit a11fd69735e6951cda9bf256d8e423696a441aa4.
>>> ---
>>>  src/storage/storage_backend_fs.c | 13 ++-----------
>>>  1 file changed, 2 insertions(+), 11 deletions(-)
>>>
>>
>> Instead of reverting why not just fix the issue.
> 
> Because I think the whole check is pointless. It's valid only when
> mounting a local filesystem, and in that case basically the same check
> is done when mounting the filesystem by the kernel.
> 

Here's the difference between the check and removing the check (not
withstanding the no PARTED and no BLKID available)...

Create a pool using ext4, start it - life is happy.  Destroy the pool.
Define a pool using xfs.  Start it

w/ my change:

# virsh pool-start fs
error: Failed to start pool fs
error: Storage pool already built: Device '/dev/sde' formatted cannot
overwrite using 'xfs', requires build --overwrite

w/o my change (e.g. if the change is reverted):

# virsh pool-start fs
error: Failed to start pool fs
error: internal error: Child process (/usr/bin/mount -t xfs /dev/sde
/home/vm-images/fs) unexpected exit status 32: mount: wrong fs type, bad
option, bad superblock on /dev/sde,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.


----

I personally like the former, but I do understand/agree that the latter
will also work.

John