dm era: Fix bitset memory leaks

Deallocate the memory allocated for the in-core bitsets when destroying
the target and in error paths.

Fixes: eec40579 ("dm: add era target")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Reviewed-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-era-target.c

@@ -47,6 +47,7 @@ struct writeset {
 static void writeset_free(struct writeset *ws)
 {
 	vfree(ws->bits);
+	ws->bits = NULL;
 }
 
 static int setup_on_disk_bitset(struct dm_disk_bitset *info,
@@ -811,6 +812,8 @@ static struct era_metadata *metadata_open(struct block_device *bdev,
 
 static void metadata_close(struct era_metadata *md)
 {
+	writeset_free(&md->writesets[0]);
+	writeset_free(&md->writesets[1]);
 	destroy_persistent_data_objects(md);
 	kfree(md);
 }
@@ -848,6 +851,7 @@ static int metadata_resize(struct era_metadata *md, void *arg)
 	r = writeset_alloc(&md->writesets[1], *new_size);
 	if (r) {
 		DMERR("%s: writeset_alloc failed for writeset 1", __func__);
+		writeset_free(&md->writesets[0]);
 		return r;
 	}
 
@@ -858,6 +862,8 @@ static int metadata_resize(struct era_metadata *md, void *arg)
 			    &value, &md->era_array_root);
 	if (r) {
 		DMERR("%s: dm_array_resize failed", __func__);
+		writeset_free(&md->writesets[0]);
+		writeset_free(&md->writesets[1]);
 		return r;
 	}