block/snapshot: remove bdrv_snapshot_delete_by_id_or_name

After the previous patch, the only instance of this function left
is inside qemu-img.c.

qemu-img is using it inside the 'img_snapshot' function to delete
snapshots in the SNAPSHOT_DELETE case, based on a "snapshot_name"
string that refers to the tag, not ID, of the QEMUSnapshotInfo struct.
This can be verified by checking the SNAPSHOT_CREATE case that
comes shortly before SNAPSHOT_DELETE. In that case, the same
"snapshot_name" variable is being strcpy to the 'name' field
of the QEMUSnapshotInfo struct sn:

pstrcpy(sn.name, sizeof(sn.name), snapshot_name);

Based on that, it is unlikely that "snapshot_name" might contain
an "id" in SNAPSHOT_DELETE.

This patch changes SNAPSHOT_DELETE to use snapshot_find() and
snapshot_delete() instead of bdrv_snapshot_delete_by_id_or_name.
After that, there is no instances left of bdrv_snapshot_delete_by_id_or_name
in the code, so it is safe to remove it entirely.

Suggested-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/snapshot.c

@@ -301,26 +301,6 @@ int bdrv_snapshot_delete(BlockDriverState *bs,
     return ret;
 }
 
-int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
-                                       const char *id_or_name,
-                                       Error **errp)
-{
-    int ret;
-    Error *local_err = NULL;
-
-    ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
-    if (ret == -ENOENT || ret == -EINVAL) {
-        error_free(local_err);
-        local_err = NULL;
-        ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
-    }
-
-    if (ret < 0) {
-        error_propagate(errp, local_err);
-    }
-    return ret;
-}
-
 int bdrv_snapshot_list(BlockDriverState *bs,
                        QEMUSnapshotInfo **psn_info)
 {

include/block/snapshot.h

@@ -61,9 +61,6 @@ int bdrv_snapshot_delete(BlockDriverState *bs,
                          const char *snapshot_id,
                          const char *name,
                          Error **errp);
-int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
-                                       const char *id_or_name,
-                                       Error **errp);
 int bdrv_snapshot_list(BlockDriverState *bs,
                        QEMUSnapshotInfo **psn_info);
 int bdrv_snapshot_load_tmp(BlockDriverState *bs,

qemu-img.c

@@ -3123,11 +3123,18 @@ static int img_snapshot(int argc, char **argv)
         break;
 
     case SNAPSHOT_DELETE:
-        bdrv_snapshot_delete_by_id_or_name(bs, snapshot_name, &err);
-        if (err) {
-            error_reportf_err(err, "Could not delete snapshot '%s': ",
-                              snapshot_name);
+        ret = bdrv_snapshot_find(bs, &sn, snapshot_name);
+        if (ret < 0) {
+            error_report("Could not delete snapshot '%s': snapshot not "
+                         "found", snapshot_name);
             ret = 1;
+        } else {
+            ret = bdrv_snapshot_delete(bs, sn.id_str, sn.name, &err);
+            if (ret < 0) {
+                error_reportf_err(err, "Could not delete snapshot '%s': ",
+                                  snapshot_name);
+                ret = 1;
+            }
         }
         break;
     }