Re: [PATCH] btrfs: allow single disk devices to mount with older generations

[Nikolay Borisov <nborisov@suse.com>]

On 2.09.20 г. 0:19 ч., Josef Bacik wrote:
> We have this check to make sure we don't accidentally add older devices
> that may have disappeared and re-appeared with an older generation from
> being added to an fs_devices.  This makes sense, we don't want stale
> disks in our file system.  However for single disks this doesn't really
> make sense.  I've seen this in testing, but I was provided a reproducer
> from a project that builds btrfs images on loopback devices.  The
> loopback device gets cached with the new generation, and then if it is
> re-used to generate a new file system we'll fail to mount it because the
> new fs is "older" than what we have in cache.
> 
> Fix this by simply ignoring this check if we're a single disk file
> system, as we're not going to cause problems for the fs by allowing the
> disk to be mounted with an older generation than what is in our cache.
> 
> I've also added a error message for this case, as it was kind of
> annoying to find originally.
> 
> Reported-by: Daan De Meyer <daandemeyer@fb.com>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---

Since you've got a reproducer is it possible to turn this into an fstests?