[Qemu-devel] [PATCH RFC 2/2] snapshot: create bdrv_snapshot_all_del_snapshot helper

["Denis V. Lunev" <den@openvz.org>]

to delete snapshots from all loaded block drivers.

The patch also ensures proper locking.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Juan Quintela <quintela@redhat.com>
---
 block/snapshot.c         | 27 ++++++++++++++++++++++++
 include/block/snapshot.h |  2 ++
 migration/savevm.c       | 54 +++++++++---------------------------------------
 3 files changed, 39 insertions(+), 44 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 6b5ce4e..9d1aa9b 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -391,3 +391,30 @@ bool bdrv_snapshot_all_can_snapshot(BlockDriverState **first_bad_bs)
     *first_bad_bs = NULL;
     return true;
 }
+
+int bdrv_snapshot_all_del_snapshot(const char *name,
+            BlockDriverState **first_bad_bs, Error **err)
+{
+    BlockDriverState *bs;
+    AioContext *ctx;
+    QEMUSnapshotInfo sn1, *snapshot = &sn1;
+
+    bs = NULL;
+    while ((bs = bdrv_next(bs))) {
+        ctx = bdrv_get_aio_context(bs);
+
+        aio_context_acquire(ctx);
+        if (bdrv_can_snapshot(bs) &&
+                bdrv_snapshot_find(bs, snapshot, name) >= 0) {
+            bdrv_snapshot_delete_by_id_or_name(bs, name, err);
+        }
+        aio_context_release(ctx);
+
+        if (*err) {
+            *first_bad_bs = bs;
+            return -1;
+        }
+    }
+
+    return 0;
+}
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 61b4b5d..4b883e5 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -84,4 +84,6 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
  */
 bool bdrv_snapshot_all_can_snapshot(BlockDriverState **first_bad_bs);
 
+int bdrv_snapshot_all_del_snapshot(const char *name,
+            BlockDriverState **first_bsd_bs, Error **err);
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 91ba0bf..4608811 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1248,35 +1248,6 @@ static BlockDriverState *find_vmstate_bs(void)
     return NULL;
 }
 
-/*
- * Deletes snapshots of a given name in all opened images.
- */
-static int del_existing_snapshots(Monitor *mon, const char *name)
-{
-    BlockDriverState *bs;
-    QEMUSnapshotInfo sn1, *snapshot = &sn1;
-    Error *err = NULL;
-
-    bs = NULL;
-    while ((bs = bdrv_next(bs))) {
-        if (bdrv_can_snapshot(bs) &&
-            bdrv_snapshot_find(bs, snapshot, name) >= 0) {
-            bdrv_snapshot_delete_by_id_or_name(bs, name, &err);
-            if (err) {
-                monitor_printf(mon,
-                               "Error while deleting snapshot on device '%s':"
-                               " %s\n",
-                               bdrv_get_device_name(bs),
-                               error_get_pretty(err));
-                error_free(err);
-                return -1;
-            }
-        }
-    }
-
-    return 0;
-}
-
 void hmp_savevm(Monitor *mon, const QDict *qdict)
 {
     BlockDriverState *bs, *bs1;
@@ -1334,7 +1305,11 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
     }
 
     /* Delete old snapshots of the same name */
-    if (name && del_existing_snapshots(mon, name) < 0) {
+    if (name && bdrv_snapshot_all_del_snapshot(name, &bs1, &local_err) < 0) {
+        monitor_printf(mon,
+                       "Error while deleting snapshot on device '%s': %s\n",
+                       bdrv_get_device_name(bs1), error_get_pretty(local_err));
+        error_free(local_err);
         goto the_end;
     }
 
@@ -1494,20 +1469,11 @@ void hmp_delvm(Monitor *mon, const QDict *qdict)
         return;
     }
 
-    bs = NULL;
-    while ((bs = bdrv_next(bs))) {
-        if (bdrv_can_snapshot(bs)) {
-            err = NULL;
-            bdrv_snapshot_delete_by_id_or_name(bs, name, &err);
-            if (err) {
-                monitor_printf(mon,
-                               "Error while deleting snapshot on device '%s':"
-                               " %s\n",
-                               bdrv_get_device_name(bs),
-                               error_get_pretty(err));
-                error_free(err);
-            }
-        }
+    if (bdrv_snapshot_all_del_snapshot(name, &bs, &err) < 0) {
+        monitor_printf(mon,
+                       "Error while deleting snapshot on device '%s': %s\n",
+                       bdrv_get_device_name(bs), error_get_pretty(err));
+        error_free(err);
     }
 }
 
-- 
2.5.0