dm thin: fix the error path for the thin device constructor

dm_pool_close_thin_device() must be called if dm_set_target_max_io_len()
fails in thin_ctr().  Otherwise __pool_destroy() will fail because the
pool will still have an open thin device:

 device-mapper: thin metadata: attempt to close pmd when 1 device(s) are still open
 device-mapper: thin: __pool_destroy: dm_pool_metadata_close() failed.

Also, must establish error code if failing thin_ctr() because the pool
is in fail_io mode.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Cc: stable@vger.kernel.org

drivers/md/dm-thin.c

@@ -2895,6 +2895,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	if (get_pool_mode(tc->pool) == PM_FAIL) {
 		ti->error = "Couldn't open thin device, Pool is in fail mode";
+		r = -EINVAL;
 		goto bad_thin_open;
 	}
 
@@ -2906,7 +2907,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	r = dm_set_target_max_io_len(ti, tc->pool->sectors_per_block);
 	if (r)
-		goto bad_thin_open;
+		goto bad_target_max_io_len;
 
 	ti->num_flush_bios = 1;
 	ti->flush_supported = true;
@@ -2927,6 +2928,8 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	return 0;
 
+bad_target_max_io_len:
+	dm_pool_close_thin_device(tc->td);
 bad_thin_open:
 	__pool_dec(tc->pool);
 bad_pool_lookup: