block: handle -EBUSY in bdrv_commit_all()

Monitor operations that manipulate image files must not execute while a
background job (like image streaming) is in progress.  This prevents
corruptions from happening when two pieces of code are manipulating the
image file without knowledge of each other.

The monitor "commit" command raises QERR_DEVICE_IN_USE when
bdrv_commit() returns -EBUSY but "commit all" has no error handling.
This is easy to fix, although note that we do not deliver a detailed
error about which device was busy in the "commit all" case.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/blockdev.c b/blockdev.c
index 96a893bed..0e8666a87 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -627,12 +627,15 @@ void do_commit(Monitor *mon, const QDict *qdict)
 {
     const char *device = qdict_get_str(qdict, "device");
     BlockDriverState *bs;
+    int ret;
 
     if (!strcmp(device, "all")) {
-        bdrv_commit_all();
+        ret = bdrv_commit_all();
+        if (ret == -EBUSY) {
+            qerror_report(QERR_DEVICE_IN_USE, device);
+            return;
+        }
     } else {
-        int ret;
-
         bs = bdrv_find(device);
         if (!bs) {
             qerror_report(QERR_DEVICE_NOT_FOUND, device);