On 10/10/16 17:34, Eric Blake wrote:
> On 10/09/2016 11:43 AM, Mark Cave-Ayland wrote:
>> The hard-coded default alignment is BDRV_SECTOR_SIZE, however this is not
>> necessarily the case for all platforms. Use this as the default alignment for
>> all current callers.
>>
>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk>
>> ---
>
>> @@ -160,8 +161,8 @@ static void dma_blk_cb(void *opaque, int ret)
>> return;
>> }
>>
>> - if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
>> - qemu_iovec_discard_back(&dbs->iov, dbs->iov.size &
>> ~BDRV_SECTOR_MASK);
>> + if (dbs->iov.size & (dbs->align - 1)) {
>> + qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & (dbs->align -
>> 1));
>
> Would it be any smarter to use osdep.h's QEMU_IS_ALIGNED(dbs->iov.size,
> dbs->align) and QEMU_ALIGN_DOWN(dbs->iov.size, dbs->align)?
> Semantically it is the same, but the macros make it obvious what the
> bit-twiddling is doing.
>
> Unless you think that needs a tweak,
> Reviewed-by: Eric Blake <ebl...@redhat.com>
I can't say I feel too strongly about it since there are plenty of other
examples of this style in the codebase, so I'm happy to go with whatever
John/Paolo are most happy with.
ATB,
Mark.
