migration: implement bdrv_all_find_vmstate_bs helper

The patch also ensures proper locking for the operation.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/block/snapshot.c b/block/snapshot.c
index 75d0b968f66df50d739c5b09b26f9cd6297ca146..6e9fa8da989139457f5902fd9c24e39920ccfa24 100644 (file)
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -469,3 +469,18 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
     *first_bad_bs = bs;
     return err;
 }
+
+BlockDriverState *bdrv_all_find_vmstate_bs(void)
+{
+    bool not_found = true;
+    BlockDriverState *bs = NULL;
+
+    while (not_found && (bs = bdrv_next(bs))) {
+        AioContext *ctx = bdrv_get_aio_context(bs);
+
+        aio_context_acquire(ctx);
+        not_found = !bdrv_can_snapshot(bs);
+        aio_context_release(ctx);
+    }
+    return bs;
+}

diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 55e995a3fecfa1912630899479cfd26f5d122159..c6910da63a43ae1983f2103795a0f96b7982c090 100644 (file)
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -91,4 +91,6 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
                              uint64_t vm_state_size,
                              BlockDriverState **first_bad_bs);
 
+BlockDriverState *bdrv_all_find_vmstate_bs(void);
+
 #endif

diff --git a/migration/savevm.c b/migration/savevm.c
index 98f9a8c6946220dfe281e228e213a6997cb0d6ff..a845e69db15d860fa9f5cdc90509c656ad5abfd3 100644 (file)
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1905,17 +1905,6 @@ int qemu_loadvm_state(QEMUFile *f)
     return ret;
 }
 
-static BlockDriverState *find_vmstate_bs(void)
-{
-    BlockDriverState *bs = NULL;
-    while ((bs = bdrv_next(bs))) {
-        if (bdrv_can_snapshot(bs)) {
-            return bs;
-        }
-    }
-    return NULL;
-}
-
 void hmp_savevm(Monitor *mon, const QDict *qdict)
 {
     BlockDriverState *bs, *bs1;
@@ -1944,8 +1933,8 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
         return;
     }
 
-    bs = find_vmstate_bs();
-    if (!bs) {
+    bs = bdrv_all_find_vmstate_bs();
+    if (bs == NULL) {
         monitor_printf(mon, "No block device can accept snapshots\n");
         return;
     }
@@ -2054,7 +2043,7 @@ int load_vmstate(const char *name)
         return ret;
     }
 
-    bs_vm_state = find_vmstate_bs();
+    bs_vm_state = bdrv_all_find_vmstate_bs();
     if (!bs_vm_state) {
         error_report("No block device supports snapshots");
         return -ENOTSUP;
@@ -2123,7 +2112,7 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
     int total;
     int *available_snapshots;
 
-    bs = find_vmstate_bs();
+    bs = bdrv_all_find_vmstate_bs();
     if (!bs) {
         monitor_printf(mon, "No available block device supports snapshots\n");
         return;