Re: dm-persistent-data: free sm_metadata on failed create

[Mike Snitzer <snitzer@redhat.com>]

Staged for 4.10 inclusion with a revised header, see:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.10&id=b34af3050734ba53a7afa4f3ab9fe9d6bbfbf802

On Thu, Dec 01 2016 at  5:58am -0500,
Edward Thornber <thornber@redhat.com> wrote:

> ack
> 
> On Wed, Nov 30, 2016 at 05:56:14PM -0600, Benjamin Marzinski wrote:
> > In dm_sm_metadata_create we temporarily change the dm_space_map
> > operations from ops, whose destroy function deallocates the
> > sm_metadata, to bootstrap_ops, whose destroy function doesn't. If we
> > fail in dm_ll_new_metadata or sm_ll_extend, we exit back to
> > dm_tm_create_internal, which calls dm_sm_destroy with the intention
> > of freeing the sm_metadata, but it doesn't.
> > 
> > This patch sets the dm_space_map operations back to ops if
> > dm_sm_metadata_create fails when it is set to bootstrap_ops.
> > 
> > Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> > ---
> >  drivers/md/persistent-data/dm-space-map-metadata.c | 14 ++++++--------
> >  1 file changed, 6 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
> > index 7e44005..20557e2 100644
> > --- a/drivers/md/persistent-data/dm-space-map-metadata.c
> > +++ b/drivers/md/persistent-data/dm-space-map-metadata.c
> > @@ -775,17 +775,15 @@ int dm_sm_metadata_create(struct dm_space_map *sm,
> >  	memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
> >  
> >  	r = sm_ll_new_metadata(&smm->ll, tm);
> > +	if (!r) {
> > +		if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
> > +			nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
> > +		r = sm_ll_extend(&smm->ll, nr_blocks);
> > +	}
> > +	memcpy(&smm->sm, &ops, sizeof(smm->sm));
> >  	if (r)
> >  		return r;
> >  
> > -	if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
> > -		nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
> > -	r = sm_ll_extend(&smm->ll, nr_blocks);
> > -	if (r)
> > -		return r;
> > -
> > -	memcpy(&smm->sm, &ops, sizeof(smm->sm));
> > -
> >  	/*
> >  	 * Now we need to update the newly created data structures with the
> >  	 * allocated blocks that they were built from.
> > -- 
> > 2.1.0
> > 
> 
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