path: root/savevm.c
diff options
authorStefan Hajnoczi <stefanha@redhat.com>2013-05-25 11:09:42 +0800
committerKevin Wolf <kwolf@redhat.com>2013-06-04 13:56:29 +0200
commit29d782710f87f01991bfc85cd9bef7d15280a5e2 (patch)
tree87fce82d0ff664d7f06e23e3f66a9276c5fc58dd /savevm.c
parent2499a096a2427f0a5c71750c9f79cf2d2d2d60f4 (diff)
block: drop bs_snapshots global variable
The bs_snapshots global variable points to the BlockDriverState which will be used to save vmstate. This is really a savevm.c concept but was moved into block.c:bdrv_snapshots() when it became clear that hotplug could result in a dangling pointer. While auditing the block layer's global state I came upon bs_snapshots and realized that a variable is not necessary here. Simply find the first BlockDriverState capable of internal snapshots each time this is needed. The behavior of bdrv_snapshots() is preserved across hotplug because new drives are always appended to the bdrv_states list. This means that calling the new find_vmstate_bs() function is idempotent - it returns the same BlockDriverState unless it was hot-unplugged. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'savevm.c')
1 files changed, 15 insertions, 4 deletions
diff --git a/savevm.c b/savevm.c
index 4e0fab6cd6..b11dbf6210 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2262,6 +2262,17 @@ out:
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;
static int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
const char *name)
@@ -2338,7 +2349,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
- bs = bdrv_snapshots();
+ bs = find_vmstate_bs();
if (!bs) {
monitor_printf(mon, "No block device can accept snapshots\n");
@@ -2440,7 +2451,7 @@ int load_vmstate(const char *name)
QEMUFile *f;
int ret;
- bs_vm_state = bdrv_snapshots();
+ bs_vm_state = find_vmstate_bs();
if (!bs_vm_state) {
error_report("No block device supports snapshots");
return -ENOTSUP;
@@ -2519,7 +2530,7 @@ void do_delvm(Monitor *mon, const QDict *qdict)
int ret;
const char *name = qdict_get_str(qdict, "name");
- bs = bdrv_snapshots();
+ bs = find_vmstate_bs();
if (!bs) {
monitor_printf(mon, "No block device supports snapshots\n");
@@ -2551,7 +2562,7 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
int *available_snapshots;
char buf[256];
- bs = bdrv_snapshots();
+ bs = find_vmstate_bs();
if (!bs) {
monitor_printf(mon, "No available block device supports snapshots\n");