On 11/12/18 2:06 AM, Marc Olson via Qemu-devel wrote:
> If 'once' is specified, the rule should execute just once, regardless if
> it is supposed to return an error or not. Take the example where you
> want the first IO to an LBA to succeed, but subsequent IOs to fail. You
> could either use state transitions, or create two rules, one with
> error = 0 and once set to true, and one with a non-zero error.
>
> Signed-off-by: Marc Olson <marco...@amazon.com>
> ---
> block/blkdebug.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 0759452..327049b 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -488,7 +488,7 @@ static int rule_check(BlockDriverState *bs, uint64_t
> offset, uint64_t bytes)
> }
> }
>
> - if (!rule || !rule->options.inject.error) {
> + if (!rule) {
> return 0;
> }
>
This gets rid of the early return so that later we check to see if
'once' was set and remove the rule, regardless of if it did anything or not,
> @@ -500,7 +500,7 @@ static int rule_check(BlockDriverState *bs, uint64_t
> offset, uint64_t bytes)
> remove_rule(rule);
> }
>
> - if (!immediately) {
> + if (error && !immediately) {
And then we modify this to only trigger if we have an error to inject.
> aio_co_schedule(qemu_get_current_aio_context(),
> qemu_coroutine_self());
> qemu_coroutine_yield();
> }
>
[down here, we return -error, but that should still be zero.]
This changes the mechanism of 'once' slightly, but only when errno was
set to zero. I'm not sure we make use of that anywhere, so I think this
should be a safe change. Certainly we don't stipulate that we only
respect once if you bothered to set errno to a non-zero value.
I thiink this is probably fine.
Reviewed-by: John Snow <js...@redhat.com>
