From c5248f79f39e5254977a3916b2149c3ccffa2722 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Sat, 20 Feb 2016 14:02:49 -0500 Subject: dm: remove support for stacking dm-mq on .request_fn device(s) Remove all fiddley code that propped up this support for a blk-mq request-queue ontop of all .request_fn devices. Testing has proven this niche request-based dm-mq mode to be buggy, when testing fault tolerance with DM multipath, and there is no point trying to preserve it. Should help improve efficiency of pure dm-mq code and make code maintenance less delicate. Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 55 ++++++++++++++++--------------------------------------- 1 file changed, 16 insertions(+), 39 deletions(-) (limited to 'drivers/md/dm.c') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 8a62e43..26fedd9 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1141,11 +1141,6 @@ static void free_rq_clone(struct request *clone) else if (!md->queue->mq_ops) /* request_fn queue stacked on request_fn queue(s) */ free_clone_request(md, clone); - /* - * NOTE: for the blk-mq queue stacked on request_fn queue(s) case: - * no need to call free_clone_request() because we leverage blk-mq by - * allocating the clone at the end of the blk-mq pdu (see: clone_rq) - */ if (!md->queue->mq_ops) free_rq_tio(tio); @@ -1866,24 +1861,18 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md, struct dm_rq_target_io *tio, gfp_t gfp_mask) { /* - * Do not allocate a clone if tio->clone was already set - * (see: dm_mq_queue_rq). + * Create clone for use with .request_fn request_queue */ - bool alloc_clone = !tio->clone; struct request *clone; - if (alloc_clone) { - clone = alloc_clone_request(md, gfp_mask); - if (!clone) - return NULL; - } else - clone = tio->clone; + clone = alloc_clone_request(md, gfp_mask); + if (!clone) + return NULL; blk_rq_init(NULL, clone); if (setup_clone(clone, rq, tio, gfp_mask)) { /* -ENOMEM */ - if (alloc_clone) - free_clone_request(md, clone); + free_clone_request(md, clone); return NULL; } @@ -2692,22 +2681,12 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, */ tio->ti = ti; - /* - * Both the table and md type cannot change after initial table load - */ - if (dm_get_md_type(md) == 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); - (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) { - /* Undo dm_start_request() before requeuing */ - rq_end_stats(md, rq); - rq_completed(md, rq_data_dir(rq), false); - return BLK_MQ_RQ_QUEUE_BUSY; - } + /* Direct call is fine since .queue_rq allows allocations */ + if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) { + /* Undo dm_start_request() before requeuing */ + rq_end_stats(md, rq); + rq_completed(md, rq_data_dir(rq), false); + return BLK_MQ_RQ_QUEUE_BUSY; } return BLK_MQ_RQ_QUEUE_OK; @@ -2726,6 +2705,11 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) struct request_queue *q; int err; + if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) { + DMERR("request-based dm-mq may only be stacked on blk-mq device(s)"); + return -EINVAL; + } + md->tag_set = kzalloc(sizeof(struct blk_mq_tag_set), GFP_KERNEL); if (!md->tag_set) return -ENOMEM; @@ -2738,10 +2722,6 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) md->tag_set->driver_data = md; md->tag_set->cmd_size = sizeof(struct dm_rq_target_io); - if (md_type == DM_TYPE_REQUEST_BASED) { - /* put the memory for non-blk-mq clone at the end of the pdu */ - md->tag_set->cmd_size += sizeof(struct request); - } err = blk_mq_alloc_tag_set(md->tag_set); if (err) @@ -2758,9 +2738,6 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) /* backfill 'mq' sysfs registration normally done in blk_register_queue */ blk_mq_register_disk(md->disk); - if (md_type == DM_TYPE_REQUEST_BASED) - init_rq_based_worker_thread(md); - return 0; out_tag_set: -- cgit v1.1