diff mbox

[v8,3/5] block: support passing 'backing': '' to 'blockdev-add'

Message ID c8b36cdf353e0a6b2b98b5750a2236f6e377e6f3.1445861886.git.berto@igalia.com
State New
Headers show

Commit Message

Alberto Garcia Oct. 26, 2015, 12:27 p.m. UTC 
Passing an empty string allows opening an image but not its backing
file. This was already described in the API documentation, only the
implementation was missing.

This is useful for creating snapshots using images opened with
blockdev-add, since they are not supposed to have a backing image
before the operation.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
---
 block.c | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox

Patch

diff --git a/block.c b/block.c
index e9f40dc..132719d 100644
--- a/block.c
+++ b/block.c
@@ -1394,6 +1394,7 @@  static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
     BlockDriverState *bs;
     BlockDriver *drv = NULL;
     const char *drvname;
+    const char *backing;
     Error *local_err = NULL;
     int snapshot_flags = 0;
 
@@ -1461,6 +1462,12 @@  static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
 
     assert(drvname || !(flags & BDRV_O_PROTOCOL));
 
+    backing = qdict_get_try_str(options, "backing");
+    if (backing && *backing == '\0') {
+        flags |= BDRV_O_NO_BACKING;
+        qdict_del(options, "backing");
+    }
+
     bs->open_flags = flags;
     bs->options = options;
     options = qdict_clone_shallow(options);