Re: [libvirt] [PATCH 1/1] storage: Fix a vol-clone bug for ppc64
On 2013年11月07日 18:41, Ján Tomko wrote:
On 11/07/2013 09:35 AM, Li Zhang wrote:
> From: Li Zhang <zhlcindy(a)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.
It doesn't look like the endianness issue.
It appends more 32 0s to the value.
I need to trace kernel to see how this happens.
Here is what I get on PPC64.
blksz = 0x1000000000000, pbsz = 0x20000000000
Actually, they should be :
blksz = 0x10000, pbsz = 0x200
On x86_64, they can get right value.
> 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/bloc...
https://lkml.org/lkml/2013/11/1/620
Ah, you are right, should be int. :)
> Signed-off-by: Li Zhang <zhlcindy(a)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.
Got it, thanks.
Jan