[libvirt] [PATCH 1/1] storage: Fix a vol-clone bug for ppc64
Li Zhang
zhlcindy at gmail.com
Fri Nov 8 05:25:39 UTC 2013
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 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.
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/block/ioctl.c#n363
> https://lkml.org/lkml/2013/11/1/620
Ah, you are right, should be int. :)
>
>> 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.
Got it, thanks.
>
> Jan
>
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