From 45714fbed4556149d7f1730f5bae74f81d5e2cd5 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 27 May 2015 15:25:27 -0400 Subject: [PATCH] dm: requeue from blk-mq dm_mq_queue_rq() using BLK_MQ_RQ_QUEUE_BUSY Use BLK_MQ_RQ_QUEUE_BUSY to requeue a blk-mq request directly from the DM blk-mq device's .queue_rq. This cleans up the previous convoluted handling of request requeueing that would return BLK_MQ_RQ_QUEUE_OK (even though it wasn't) and then run blk_mq_requeue_request() followed by blk_mq_kick_requeue_list(). Also, document that DM blk-mq ontop of old request_fn devices cannot fail in clone_rq() since the clone request is preallocated as part of the pdu. Reported-by: Christoph Hellwig Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 1c62ed8d09f4..1badfb250a18 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2754,13 +2754,15 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, if (dm_table_get_type(map) == DM_TYPE_REQUEST_BASED) { /* clone request is allocated at the end of the pdu */ tio->clone = (void *)blk_mq_rq_to_pdu(rq) + sizeof(struct dm_rq_target_io); - if (!clone_rq(rq, md, tio, GFP_ATOMIC)) - return BLK_MQ_RQ_QUEUE_BUSY; + (void) clone_rq(rq, md, tio, GFP_ATOMIC); queue_kthread_work(&md->kworker, &tio->work); } else { /* Direct call is fine since .queue_rq allows allocations */ - if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) - dm_requeue_unmapped_original_request(md, rq); + if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) { + /* Undo dm_start_request() before requeuing */ + rq_completed(md, rq_data_dir(rq), false); + return BLK_MQ_RQ_QUEUE_BUSY; + } } return BLK_MQ_RQ_QUEUE_OK; -- 2.20.1