[Qemu-devel] [PATCH] block: Use backing format driver during image creation

[Qemu-devel] [PATCH] block: Use backing format driver during image creation

[Stefan Hajnoczi]

The backing format should be honored during image creation.  For some
reason we currently use the image format to open the backing file.  This
fails when the backing file has a different format than the image being
created.  Keep the image and backing format drivers completely separate.

Also print the backing filename if there is an error opening the backing
file instead of the image filename.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 block.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index ff2795b..7ad3ddf 100644
--- a/block.c
+++ b/block.c
@@ -2778,6 +2778,7 @@ int bdrv_img_create(const char *filename, const char *fmt,
     QEMUOptionParameter *backing_fmt, *backing_file;
     BlockDriverState *bs = NULL;
     BlockDriver *drv, *proto_drv;
+    BlockDriver *backing_drv = NULL;
     int ret = 0;
 
     /* Find driver and parse its options */
@@ -2846,7 +2847,8 @@ int bdrv_img_create(const char *filename, const char *fmt,
 
     backing_fmt = get_option_parameter(param, BLOCK_OPT_BACKING_FMT);
     if (backing_fmt && backing_fmt->value.s) {
-        if (!bdrv_find_format(backing_fmt->value.s)) {
+        backing_drv = bdrv_find_format(backing_fmt->value.s);
+        if (!backing_drv) {
             error_report("Unknown backing file format '%s'",
                          backing_fmt->value.s);
             ret = -EINVAL;
@@ -2863,9 +2865,9 @@ int bdrv_img_create(const char *filename, const char *fmt,
 
             bs = bdrv_new("");
 
-            ret = bdrv_open(bs, backing_file->value.s, flags, drv);
+            ret = bdrv_open(bs, backing_file->value.s, flags, backing_drv);
             if (ret < 0) {
-                error_report("Could not open '%s'", filename);
+                error_report("Could not open '%s'", backing_file->value.s);
                 goto out;
             }
             bdrv_get_geometry(bs, &size);
-- 
1.7.2.3

[Qemu-devel] Re: [PATCH] block: Use backing format driver during image creation

[Jes Sorensen]

On 01/24/11 10:32, Stefan Hajnoczi wrote:
> The backing format should be honored during image creation.  For some
> reason we currently use the image format to open the backing file.  This
> fails when the backing file has a different format than the image being
> created.  Keep the image and backing format drivers completely separate.
> 
> Also print the backing filename if there is an error opening the backing
> file instead of the image filename.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
>  block.c |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
> 

Looks good!

Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>

[Qemu-devel] Re: [PATCH] block: Use backing format driver during image creation

[Kevin Wolf]

Am 24.01.2011 10:32, schrieb Stefan Hajnoczi:
> The backing format should be honored during image creation.  For some
> reason we currently use the image format to open the backing file.  This
> fails when the backing file has a different format than the image being
> created.  Keep the image and backing format drivers completely separate.
> 
> Also print the backing filename if there is an error opening the backing
> file instead of the image filename.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Thanks, applied to the block branch.

I think we'll want to have a qemu-iotests case for this kind of regressions.

Kevin