Re: [PATCH] btrfs: harden identification of the stale device

[Anand Jain <anand.jain@oracle.com>]

On 08/12/2021 22:29, Josef Bacik wrote:
> On Wed, Dec 08, 2021 at 10:05:29PM +0800, Anand Jain wrote:
>> Identifying and removing the stale device from the fs_uuids list is done
>> by the function btrfs_free_stale_devices().
>> btrfs_free_stale_devices() in turn depends on the function
>> device_path_matched() to check if the device repeats in more than one
>> btrfs_device structure.
>>
>> The matching of the device happens by its path, the device path. However,
>> when dm mapper is in use, the dm device paths are nothing but a link to
>> the actual block device, which leads to the device_path_matched() failing
>> to match.
>>
>> Fix this by matching the dev_t as provided by lookup_bdev() instead of
>> plain strcmp() the device paths.
>>
>> Reported-by: Josef Bacik <josef@toxicpanda.com>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> 
> We already have the bdev for the device in most of the callers here, the only
> exception is btrfs_forget_devices.  Can we change this up to pass in the dev_t
> of the device we're trying to remove, that way we don't have to do the lookup
> over and over for the path of the device we're trying to forget?  Thanks,

Right. I have made the related changes and, in v2, this change is on top 
of this patch.

Thanks, Anand


> 
> Josef