[Qemu-block] [PATCH RFC v2 1/1] block: pass the right options for BlockDriver.bdrv_open

[Dong Jia Shi]

raw_open() expects the caller always passing in the right actual
@options parameter. But when trying to applying snapshot on a RBD
image, bdrv_snapshot_goto() calls raw_open() (by calling the
bdrv_open callback on the BlockDriver) with a NULL @options, and
that will result in a Segmentation fault.

For the other non-raw format drivers, it also make sense to passing
in the actual options, althought they don't trigger the problem so
far.

Let's prepare a @options by adding the "file" key-value pair to a
copy of the actual options that were given for the node (i.e.
bs->options), and pass it to the callback.

Signed-off-by: Dong Jia Shi <address@hidden>
---
 block/snapshot.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index bf5c2ca..dfec139 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -27,6 +27,7 @@
 #include "block/block_int.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
+#include "qapi/qmp/qstring.h"
 
 QemuOptsList internal_snapshot_opts = {
     .name = "snapshot",
@@ -189,9 +190,14 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
     }
 
     if (bs->file) {
+        QDict *options = qdict_clone_shallow(bs->options);
+        qdict_put(options, "file",
+                  qstring_from_str(bdrv_get_node_name(bs->file->bs)));
+
         drv->bdrv_close(bs);
         ret = bdrv_snapshot_goto(bs->file->bs, snapshot_id);
-        open_ret = drv->bdrv_open(bs, NULL, bs->open_flags, NULL);
+        open_ret = drv->bdrv_open(bs, options, bs->open_flags, NULL);
+        QDECREF(options);
         if (open_ret < 0) {
             bdrv_unref(bs->file->bs);
             bs->drv = NULL;
-- 
2.8.4