Re: [Qemu-devel] [PATCH 1/1] qemu-img: Cannot create fixed vhdx image

Re: [Qemu-devel] [PATCH 1/1] qemu-img: Cannot create fixed vhdx image

[Michael Tokarev]

18.09.2014 19:17, Adelina Tuvenie wrote:
> 
> When trying to create a fixed vhd image qemu-img will return the
> following error:
> 
> qemu-img: test.vhdx: Could not create image: Cannot allocate memory
> 
> This happens because of a incorrect check in vhdx.c. Specifficaly,
> in vhdx_create_bat(), after allocating memory for the BAT entry,
> there is a check to determine if the allocation was unsuccsessful.
> The error comes from the fact that it checks if s->bat isn't NULL,
> which is true in case of succsessful allocation,  and exits with
> error ENOMEM.

Applying to -trivial, as it is an obvious trivial one-liner, hopefully
it's okay for kwolf@ and stefanha@.  But please,

 - Cc qemu-devel and the subsystem maintainers (Cc'ed)
 - do not send an "intro" email for single patches
 - do not attach the patch, place it inline if possible

(Since the original patch was in an attachment, I copy it here for
completness:

diff --git a/block/vhdx.c b/block/vhdx.c
index 796b7bd..5bf292e 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1593,7 +1593,7 @@ static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
                 bdrv_has_zero_init(bs) == 0) {
         /* for a fixed file, the default BAT entry is not zero */
         s->bat = g_try_malloc0(length);
-        if (length && s->bat != NULL) {
+        if (length && s->bat == NULL) {
             ret = -ENOMEM;
             goto exit;
         }
)

I also modified the subject line, to read:

  block: allow creation of fixed vhdx images

Thanks,

/mjt

Re: [Qemu-devel] [PATCH 1/1] qemu-img: Cannot create fixed vhdx image

[Kevin Wolf]

Am 20.09.2014 um 15:53 hat Michael Tokarev geschrieben:
> 18.09.2014 19:17, Adelina Tuvenie wrote:
> > 
> > When trying to create a fixed vhd image qemu-img will return the
> > following error:
> > 
> > qemu-img: test.vhdx: Could not create image: Cannot allocate memory
> > 
> > This happens because of a incorrect check in vhdx.c. Specifficaly,
> > in vhdx_create_bat(), after allocating memory for the BAT entry,
> > there is a check to determine if the allocation was unsuccsessful.
> > The error comes from the fact that it checks if s->bat isn't NULL,
> > which is true in case of succsessful allocation,  and exits with
> > error ENOMEM.
> 
> Applying to -trivial, as it is an obvious trivial one-liner, hopefully
> it's okay for kwolf@ and stefanha@.  But please,
> 
>  - Cc qemu-devel and the subsystem maintainers (Cc'ed)
>  - do not send an "intro" email for single patches
>  - do not attach the patch, place it inline if possible
> 
> (Since the original patch was in an attachment, I copy it here for
> completness:
> 
> diff --git a/block/vhdx.c b/block/vhdx.c
> index 796b7bd..5bf292e 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -1593,7 +1593,7 @@ static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
>                  bdrv_has_zero_init(bs) == 0) {
>          /* for a fixed file, the default BAT entry is not zero */
>          s->bat = g_try_malloc0(length);
> -        if (length && s->bat != NULL) {
> +        if (length && s->bat == NULL) {
>              ret = -ENOMEM;
>              goto exit;
>          }
> )

Whoops, this is what happens when you make mechanical changes manually.
And I fooled two reviewers with this code. :-)

Acked-by: Kevin Wolf <kwolf@redhat.com>