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authorMike Snitzer <snitzer@redhat.com>2015-05-27 15:25:27 -0400
committerMike Snitzer <snitzer@redhat.com>2015-05-27 17:37:23 -0400
commit45714fbed4556149d7f1730f5bae74f81d5e2cd5 (patch)
tree7bebdecc13511fc03de8b4d08e98d967c45d5d3b
parent4c6dd53dd3674c310d7379c6b3273daa9fd95c79 (diff)
downloadlinux-stericsson-45714fbed4556149d7f1730f5bae74f81d5e2cd5.tar.gz
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 <hch@lst.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r--drivers/md/dm.c10
1 files 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;