[dm-devel] [PATCH] dm: avoid filesystem lookup in dm_get_dev_t()

[Martin Wilck]

On Thu, 2020-12-10 at 18:11 +0100, Martin Wilck wrote:
> On Thu, 2020-12-10 at 10:24 +0100, Hannes Reinecke wrote:
> > dm_get_dev_t() is just used to convert an arbitrary 'path' string
> > into a dev_t. It doesn't presume that the device is present; that
> > check will be done later, as the only caller is dm_get_device(),
> > which does a dm_get_table_device() later on, which will properly
> > open the device.
> > So if the path string already _is_ in major:minor representation
> > we can convert it directly, avoiding a recursion into the
> > filesystem
> > to lookup the block device.
> > This avoids a hang in multipath_message() when the filesystem is
> > inaccessible.
> > 
> > Signed-off-by: Hannes Reinecke <hare at suse.de>
> 
> Ack, although I believe the scsi/__GENKSYMS__ part doesn't belong
> here.
> 
> Note that this is essentially a revert/fix of 644bda6f3460 ("dm
> table:
> fall back to getting device using name_to_dev_t()"). Added the author
> of that patch to CC.

Mike, do you need anything more to apply this one? Do you want a
cleaned-up resend?

Cheers,
Martin