block: check bdrv_in_use() before blockdev operations

Long-running block operations like block migration and image streaming
must have continual access to their block device.  It is not safe to
perform operations like hotplug, eject, change, resize, commit, or
external snapshot while a long-running operation is in progress.

This patch adds the missing bdrv_in_use() checks so that block migration
and image streaming never have the rug pulled out from underneath them.

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

diff --git a/block.c b/block.c
index 3f072f62748ba1676d8a3263d21a4e03c5e96d36..43f648437d148eb50b4c75d37c38145dca8a6a0d 100644 (file)
--- a/block.c
+++ b/block.c
@@ -1020,6 +1020,10 @@ int bdrv_commit(BlockDriverState *bs)
         return -EACCES;
     }
 
+    if (bdrv_in_use(bs) || bdrv_in_use(bs->backing_hd)) {
+        return -EBUSY;
+    }
+
     backing_drv = bs->backing_hd->drv;
     ro = bs->backing_hd->read_only;
     strncpy(filename, bs->backing_hd->filename, sizeof(filename));

diff --git a/blockdev.c b/blockdev.c
index 1f83c888e7fe96773c4f0b298154a863f1f75940..0499ee6aea5f67cd461006e5ac59675eae8715b2 100644 (file)
--- a/blockdev.c
+++ b/blockdev.c
@@ -592,12 +592,18 @@ void do_commit(Monitor *mon, const QDict *qdict)
     if (!strcmp(device, "all")) {
         bdrv_commit_all();
     } else {
+        int ret;
+
         bs = bdrv_find(device);
         if (!bs) {
             qerror_report(QERR_DEVICE_NOT_FOUND, device);
             return;
         }
-        bdrv_commit(bs);
+        ret = bdrv_commit(bs);
+        if (ret == -EBUSY) {
+            qerror_report(QERR_DEVICE_IN_USE, device);
+            return;
+        }
     }
 }
 
@@ -616,6 +622,10 @@ void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
         error_set(errp, QERR_DEVICE_NOT_FOUND, device);
         return;
     }
+    if (bdrv_in_use(bs)) {
+        error_set(errp, QERR_DEVICE_IN_USE, device);
+        return;
+    }
 
     pstrcpy(old_filename, sizeof(old_filename), bs->filename);
 
@@ -667,6 +677,10 @@ void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
 
 static void eject_device(BlockDriverState *bs, int force, Error **errp)
 {
+    if (bdrv_in_use(bs)) {
+        error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
+        return;
+    }
     if (!bdrv_dev_has_removable_media(bs)) {
         error_set(errp, QERR_DEVICE_NOT_REMOVABLE, bdrv_get_device_name(bs));
         return;