Am 26.10.2015 um 07:24 hat Fam Zheng geschrieben:
> Both bdrv_discard and bdrv_aio_discard will call into bdrv_co_discard,
> so add tracked_request_begin/end calls around the loop.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> block/io.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/block/io.c b/block/io.c
> index 223c4e9..abb3aaa 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -2415,7 +2415,8 @@ static void coroutine_fn bdrv_discard_co_entry(void
> *opaque)
> int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
> int nb_sectors)
> {
> - int max_discard, ret;
> + BdrvTrackedRequest req;
> + int max_discard, ret = 0;
>
> if (!bs->drv) {
> return -ENOMEDIUM;
> @@ -2437,6 +2438,8 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs,
> int64_t sector_num,
> return 0;
> }
>
> + tracked_request_begin(&req, bs, sector_num, nb_sectors,
> + BDRV_TRACKED_DISCARD);
> bdrv_set_dirty(bs, sector_num, nb_sectors);
>
> max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS);
> @@ -2470,20 +2473,23 @@ int coroutine_fn bdrv_co_discard(BlockDriverState
> *bs, int64_t sector_num,
> acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
> bdrv_co_io_em_complete, &co);
> if (acb == NULL) {
> - return -EIO;
> + ret = -EIO;
> + goto out;
> } else {
> qemu_coroutine_yield();
> ret = co.ret;
> }
> }
> if (ret && ret != -ENOTSUP) {
> - return ret;
> + goto out;
> }
>
> sector_num += num;
> nb_sectors -= num;
> }
> - return 0;
> +out:
> + tracked_request_end(&req);
> + return ret;
> }
I would prefer an explicit ret = 0 before the out label because
otherwise you're relying on the previous value that has been set
somewhere in the loop. As far as I can tell, it's still correct, but it
makes it needlessly hard to tell whether success is 0 or >= 0.
Kevin
