If blk_mq_try_issue_directly() returns BLK_STS*_RESOURCE that means that the request has not been queued and that the caller should retry to submit the request. Both blk_mq_request_bypass_insert() and blk_mq_sched_insert_request() guarantee that a request will be processed. Hence return BLK_STS_OK if one of these functions is called. This patch avoids that blk_mq_dispatch_rq_list() crashes when using dm-mpath.
Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: James Smart <[email protected]> Cc: Ming Lei <[email protected]> Cc: Jianchao Wang <[email protected]> Cc: Keith Busch <[email protected]> Cc: Dongli Zhang <[email protected]> Cc: Laurence Oberman <[email protected]> Tested-by: Laurence Oberman <[email protected]> Reviewed-by: Laurence Oberman <[email protected]> Reported-by: Laurence Oberman <[email protected]> Fixes: 7f556a44e61d ("blk-mq: refactor the code of issue request directly") # v5.0. Cc: <[email protected]> Signed-off-by: Bart Van Assche <[email protected]> --- block/blk-mq.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 652d0c6d5945..b2c20dce8a30 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1859,16 +1859,11 @@ blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, case BLK_STS_RESOURCE: if (force) { blk_mq_request_bypass_insert(rq, run_queue); - /* - * We have to return BLK_STS_OK for the DM - * to avoid livelock. Otherwise, we return - * the real result to indicate whether the - * request is direct-issued successfully. - */ - ret = bypass ? BLK_STS_OK : ret; + ret = BLK_STS_OK; } else if (!bypass) { blk_mq_sched_insert_request(rq, false, run_queue, false); + ret = BLK_STS_OK; } break; default: -- 2.21.0.196.g041f5ea1cf98
