On 04/24/2018 10:40 AM, Kevin Wolf wrote: > Am 15.02.2018 um 20:28 hat Eric Blake geschrieben: >> We are gradually moving away from sector-based interfaces, towards >> byte-based. Add new sector-based aio callbacks for read and write, >> to match the fact that bdrv_aio_pdiscard is already byte-based. >> >> Ideally, drivers should be converted to use coroutine callbacks >> rather than aio; but that is not quite as trivial (if we do that >> conversion, the null-aio driver will disappear), so for the >> short term, converting the signature but keeping things with aio >> is easier. Once all drivers are converted, the sector-based aio >> callbacks will be removed. >> >> Signed-off-by: Eric Blake <[email protected]> >> --- >> include/block/block_int.h | 6 ++++++ >> block/io.c | 37 +++++++++++++++++++++++++++---------- >> 2 files changed, 33 insertions(+), 10 deletions(-) >>
>> +++ b/block/io.c
>> @@ -934,9 +934,11 @@ static int coroutine_fn
>> bdrv_driver_preadv(BlockDriverState *bs,
>> sector_num = offset >> BDRV_SECTOR_BITS;
>> nb_sectors = bytes >> BDRV_SECTOR_BITS;
>>
>> - assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
>> - assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
>> - assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
>> + if (!drv->bdrv_aio_preadv) {
>> + assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
>> + assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
>> + assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
>> + }
>
> Hm, this is kind of ugly. Previously, we handled everything byte-aligned
> in the first section, now we mix both in the second section.
>
> I can see that you do this so you don't have to duplicate the acb and
> coroutine yielding code below, but can we move things into the right
> place in the final patch at least? That is, calculate sector_num and
> nb_sectors only if all the byte-based interfaces weren't available.
Yeah, that's easy enough to squash into patch 6:
diff --git i/block/io.c w/block/io.c
index ba767612931..49fabe8eeb1 100644
--- i/block/io.c
+++ w/block/io.c
@@ -924,16 +924,13 @@ static int coroutine_fn
bdrv_driver_preadv(BlockDriverState *bs,
return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
}
- sector_num = offset >> BDRV_SECTOR_BITS;
- nb_sectors = bytes >> BDRV_SECTOR_BITS;
-
- if (!drv->bdrv_aio_preadv) {
- assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
- assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
- assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
- }
-
if (drv->bdrv_co_readv) {
+ sector_num = offset >> BDRV_SECTOR_BITS;
+ nb_sectors = bytes >> BDRV_SECTOR_BITS;
+
+ assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
+ assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+ assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
} else {
BlockAIOCB *acb;
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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