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Re: [Qemu-devel] [Qemu-block] [PATCH for-2.6 2/2] block: Fix blk_aio_wri
Re: [Qemu-devel] [Qemu-block] [PATCH for-2.6 2/2] block: Fix blk_aio_write_zeroes()
Fri, 15 Apr 2016 01:30:09 +0200
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On 13.04.2016 13:06, Kevin Wolf wrote:
> Commit 57d6a428 broke blk_aio_write_zeroes() because in some write
> functions in the call path don't have an explicit length argument but
> reuse qiov->size instead. Which is great, except that write_zeroes
> doesn't have a qiov, which this commit interprets as 0 bytes.
> Consequently, blk_aio_write_zeroes() didn't effectively do anything.
You mean it has written null data? :-)
Alternative version: So it has written zero bytes? Works as intended, then.
> This patch introduces an explicit acb->bytes in BlkAioEmAIOCB and uses
> that instead of acb->rwco.size.
> The synchronous version of the function is okay because it does pass a
> qiov (with the right size and a NULL pointer as its base).
> Signed-off-by: Kevin Wolf <address@hidden>
> block/block-backend.c | 20 +++++++----
> tests/qemu-iotests/033 | 8 +++--
> tests/qemu-iotests/033.out | 82
> 3 files changed, 100 insertions(+), 10 deletions(-)
> diff --git a/block/block-backend.c b/block/block-backend.c
> index d74f670..140c3f7 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -937,7 +940,8 @@ BlockAIOCB *blk_aio_write_zeroes(BlockBackend *blk,
> int64_t sector_num,
> return blk_abort_aio_request(blk, cb, opaque, -EINVAL);
> - return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, NULL,
> + return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS,
> + nb_sectors << BDRV_SECTOR_BITS, NULL,
> blk_aio_write_entry, BDRV_REQ_ZERO_WRITE, cb,
Another thing about blk_aio_write_zeroes() that might need fixing is
that it completely ignores its flags parameter.
That can be done in a seperate patch, however (and is probably not
critical, as this currently just means that a potential REQ_MAY_UNMAP
from scsi-disk is ignored), so:
Reviewed-by: Max Reitz <address@hidden>
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