From 29d782710f87f01991bfc85cd9bef7d15280a5e2 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Sat, 25 May 2013 11:09:42 +0800 Subject: 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 Reviewed-by: Eric Blake Reviewed-by: Wenchao Xia Signed-off-by: Wenchao Xia Signed-off-by: Kevin Wolf --- savevm.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'savevm.c') diff --git a/savevm.c b/savevm.c index 4e0fab6..b11dbf6 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"); return; @@ -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"); return; @@ -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"); return; -- cgit v1.1