[Qemu-devel] [PATCH v7 13/24] block: Allow recursive "file"s

[Max Reitz <mreitz@redhat.com>]

It should be possible to use a format as a driver for a file which in
turn requires another file, i.e., nesting file formats.

Allowing nested file formats results in e.g. qcow2 BlockDriverStates
never being directly passed to bdrv_open_common() from bdrv_file_open(),
but instead being handed through bdrv_open(). This changes the error
message when trying to give a filename to qcow2, i.e. trying to use it
as a driver for the protocol level. Therefore, change the reference
output of I/O test 051 accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                    | 9 +++++++--
 tests/qemu-iotests/051.out | 2 +-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index 9e4e85f..6af5f6e 100644
--- a/block.c
+++ b/block.c
@@ -948,14 +948,19 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
         goto fail;
     }
 
-    ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
+    if (!drv->bdrv_file_open) {
+        ret = bdrv_open(bs, filename, options, flags, drv, &local_err);
+        options = NULL;
+    } else {
+        ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
+    }
     if (ret < 0) {
         error_propagate(errp, local_err);
         goto fail;
     }
 
     /* Check if any unknown options were used */
-    if (qdict_size(options) != 0) {
+    if (options && (qdict_size(options) != 0)) {
         const QDictEntry *entry = qdict_first(options);
         error_setg(errp, "Block protocol '%s' doesn't support the option '%s'",
                    drv->format_name, entry->key);
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index c2cadba..d0c5173 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -222,7 +222,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) q^[[K^[[Dqu^[[K^[[D^[[Dqui^[[K^[[D^[[D^[[Dquit^[[K
 
 Testing: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2
-QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2: could not open disk image TEST_DIR/t.qcow2: Can't use 'qcow2' as a block driver for the protocol level
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2: could not open disk image TEST_DIR/t.qcow2: Block format 'qcow2' used by device '' doesn't support the option 'filename'
 
 
 === Parsing protocol from file name ===
-- 
1.8.5.1