On 12/6/18 3:28 PM, Mike Snitzer wrote: > On Thu, Dec 06 2018 at 5:20pm -0500, > Jens Axboe <[email protected]> wrote: > >> After the direct dispatch corruption fix, we permanently disallow direct >> dispatch of non read/write requests. This works fine off the normal IO >> path, as they will be retried like any other failed direct dispatch >> request. But for the blk_insert_cloned_request() that only DM uses to >> bypass the bottom level scheduler, we always first attempt direct >> dispatch. For some types of requests, that's now a permanent failure, >> and no amount of retrying will make that succeed. >> >> Don't use direct dispatch off the cloned insert path, always just use >> bypass inserts. This still bypasses the bottom level scheduler, which is >> what DM wants. >> >> Fixes: ffe81d45322c ("blk-mq: fix corruption with direct issue") >> Signed-off-by: Jens Axboe <[email protected]> >> >> --- >> >> diff --git a/block/blk-core.c b/block/blk-core.c >> index deb56932f8c4..4c44e6fa0d08 100644 >> --- a/block/blk-core.c >> +++ b/block/blk-core.c >> @@ -2637,7 +2637,8 @@ blk_status_t blk_insert_cloned_request(struct >> request_queue *q, struct request * >> * bypass a potential scheduler on the bottom device for >> * insert. >> */ >> - return blk_mq_request_issue_directly(rq); >> + blk_mq_request_bypass_insert(rq, true); >> + return BLK_STS_OK; >> } >> >> spin_lock_irqsave(q->queue_lock, flags); > > Not sure what this trailing spin_lock_irqsave(q->queue_lock, flags) is > about.. but this looks good.
It's because it's against current -git, that is gone from the 4.21 branch. > I'll cleanup dm-rq.c to do away with the > extra STS_RESOURCE checks for its call to blk_insert_cloned_request() > once this lands. That is indeed a nice benefit, all source based failure cases can be removed from the caller after this. -- Jens Axboe
