Am 10.04.2017 um 17:05 hat Fam Zheng geschrieben:
> bdrv_inc_in_flight and bdrv_dec_in_flight are mandatory for
> BDRV_POLL_WHILE to work, even for the shortcut case where flush is
> unnecessary. Move the if block to below bdrv_dec_in_flight, and BTW fix
> the variable declaration position.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> block/io.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/block/io.c b/block/io.c
> index 00e45ca..bae6947 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -2278,16 +2278,17 @@ static void coroutine_fn bdrv_flush_co_entry(void
> *opaque)
>
> int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
> {
> - int ret;
> -
> - if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
> - bdrv_is_sg(bs)) {
> - return 0;
> - }
> + int current_gen;
> + int ret = 0;
>
> bdrv_inc_in_flight(bs);
As Coverity points out, we're now using bs...
> - int current_gen = bs->write_gen;
> + if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
...before doing the NULL check.
I'm not sure if we even need to have a NULL check here, but we would have
to check all callers to make sure that it's unnecessary. Before commit
29cdb251, it only checked bs->drv and I don't see how that commit
introduced a NULL caller, but maybe one was added later.
In any case, bdrv_co_flush() needs a fix, either remove the NULL check
or do it first.
> + bdrv_is_sg(bs)) {
> + goto early_exit;
> + }
Kevin
