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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 <snitzer@redhat.com>
hifive-unleashed-5.1
Mike Snitzer 2016-02-20 14:02:49 -05:00
parent 818c5f3bef
commit c5248f79f3
2 changed files with 20 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/md/dm-mpath.c
View File

@ -418,7 +418,10 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
spin_unlock_irq(&m->lock);
if (clone) {
/* Old request-based interface: allocated clone is passed in */
/*
* Old request-based interface: allocated clone is passed in.
* Used by: .request_fn stacked on .request_fn path(s).
*/
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;

55
drivers/md/dm.c
View File

@ -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: