[libvirt] [PATCH 1/1] storage: Fix a vol-clone bug for ppc64

[Ján Tomko]

On 11/07/2013 09:35 AM, Li Zhang wrote:
> From: Li Zhang <zhlcindy at linux.vnet.ibm.com>
> 
> vol-clone reports out of memory error with disk type on ppc64.
> 
> Currently, wbytes is defined as size_t type which is 8 bytes on ppc64, 
> but args's value in ioctl(fd, args..) in kernel is unsigned int. 
> So it will read more 4 bytes by ioctl() with size_t from memory which 
> gets a large number and causes out of memory error.

On x86_64 size_t is 8 bytes and int is 4 bytes, I guess this is an endianness issue.

> 
> This patch changes size_t to unsigned int to synchronize with kernel.

The type in the kernel seems to be int:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/block/ioctl.c#n363
https://lkml.org/lkml/2013/11/1/620

> 
> Signed-off-by: Li Zhang <zhlcindy at linux.vnet.ibm.com>
> ---
>  src/storage/storage_backend.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index 4b1b00d..f510080 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -135,7 +135,7 @@ virStorageBackendCopyToFD(virStorageVolDefPtr vol,
>      int amtread = -1;
>      int ret = 0;
>      size_t rbytes = READ_BLOCK_SIZE_DEFAULT;
> -    size_t wbytes = 0;
> +    unsigned int wbytes = 0;
>      int interval;
>      char *zerobuf = NULL;
>      char *buf = NULL;
> 

I'll push this with s/unsigned // later, unless someone has a different opinion.

Jan

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