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dm: distinquish old .request_fn (dm-old) vs dm-mq request-based DM
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Rename various methods to have either a "dm_old" or "dm_mq" prefix.
Improve code comments to assist with understanding the duality of code
that handles both "dm_old" and "dm_mq" cases.

It is no much easier to quickly look at the code and _know_ that a given
method is either 1) "dm_old" only 2) "dm_mq" only 3) common to both.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Mike Snitzer committed Feb 23, 2016
1 parent c5248f7 commit eca7ee6
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Showing 2 changed files with 58 additions and 50 deletions.
6 changes: 5 additions & 1 deletion drivers/md/dm-mpath.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -426,7 +426,11 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
} else {
/* blk-mq request-based interface */
/*
* blk-mq request-based interface; used by both:
* .request_fn stacked on blk-mq path(s) and
* blk-mq stacked on blk-mq path(s).
*/
*__clone = blk_get_request(bdev_get_queue(bdev),
rq_data_dir(rq), GFP_ATOMIC);
if (IS_ERR(*__clone)) {
Expand Down
102 changes: 53 additions & 49 deletions drivers/md/dm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -333,7 +333,7 @@ static int __init local_init(void)
if (!_rq_tio_cache)
goto out_free_io_cache;

_rq_cache = kmem_cache_create("dm_clone_request", sizeof(struct request),
_rq_cache = kmem_cache_create("dm_old_clone_request", sizeof(struct request),
__alignof__(struct request), 0, NULL);
if (!_rq_cache)
goto out_free_rq_tio_cache;
Expand Down Expand Up @@ -652,24 +652,24 @@ static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
bio_put(&tio->clone);
}

static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
gfp_t gfp_mask)
static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md,
gfp_t gfp_mask)
{
return mempool_alloc(md->io_pool, gfp_mask);
}

static void free_rq_tio(struct dm_rq_target_io *tio)
static void free_old_rq_tio(struct dm_rq_target_io *tio)
{
mempool_free(tio, tio->md->io_pool);
}

static struct request *alloc_clone_request(struct mapped_device *md,
gfp_t gfp_mask)
static struct request *alloc_old_clone_request(struct mapped_device *md,
gfp_t gfp_mask)
{
return mempool_alloc(md->rq_pool, gfp_mask);
}

static void free_clone_request(struct mapped_device *md, struct request *rq)
static void free_old_clone_request(struct mapped_device *md, struct request *rq)
{
mempool_free(rq, md->rq_pool);
}
Expand Down Expand Up @@ -1140,10 +1140,10 @@ static void free_rq_clone(struct request *clone)
tio->ti->type->release_clone_rq(clone);
else if (!md->queue->mq_ops)
/* request_fn queue stacked on request_fn queue(s) */
free_clone_request(md, clone);
free_old_clone_request(md, clone);

if (!md->queue->mq_ops)
free_rq_tio(tio);
free_old_rq_tio(tio);
}

/*
Expand Down Expand Up @@ -1193,13 +1193,13 @@ static void dm_unprep_request(struct request *rq)
if (clone)
free_rq_clone(clone);
else if (!tio->md->queue->mq_ops)
free_rq_tio(tio);
free_old_rq_tio(tio);
}

/*
* Requeue the original request of a clone.
*/
static void old_requeue_request(struct request *rq)
static void dm_old_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
unsigned long flags;
Expand Down Expand Up @@ -1231,14 +1231,14 @@ static void dm_requeue_original_request(struct mapped_device *md,

rq_end_stats(md, rq);
if (!rq->q->mq_ops)
old_requeue_request(rq);
dm_old_requeue_request(rq);
else
dm_mq_requeue_request(rq);

rq_completed(md, rw, false);
}

static void old_stop_queue(struct request_queue *q)
static void dm_old_stop_queue(struct request_queue *q)
{
unsigned long flags;

Expand All @@ -1252,15 +1252,15 @@ static void old_stop_queue(struct request_queue *q)
spin_unlock_irqrestore(q->queue_lock, flags);
}

static void stop_queue(struct request_queue *q)
static void dm_stop_queue(struct request_queue *q)
{
if (!q->mq_ops)
old_stop_queue(q);
dm_old_stop_queue(q);
else
blk_mq_stop_hw_queues(q);
}

static void old_start_queue(struct request_queue *q)
static void dm_old_start_queue(struct request_queue *q)
{
unsigned long flags;

Expand All @@ -1270,10 +1270,10 @@ static void old_start_queue(struct request_queue *q)
spin_unlock_irqrestore(q->queue_lock, flags);
}

static void start_queue(struct request_queue *q)
static void dm_start_queue(struct request_queue *q)
{
if (!q->mq_ops)
old_start_queue(q);
dm_old_start_queue(q);
else {
blk_mq_start_stopped_hw_queues(q, true);
blk_mq_kick_requeue_list(q);
Expand Down Expand Up @@ -1328,7 +1328,7 @@ static void dm_softirq_done(struct request *rq)
if (!rq->q->mq_ops) {
blk_end_request_all(rq, tio->error);
rq_completed(tio->md, rw, false);
free_rq_tio(tio);
free_old_rq_tio(tio);
} else {
blk_mq_end_request(rq, tio->error);
rq_completed(tio->md, rw, false);
Expand Down Expand Up @@ -1370,7 +1370,7 @@ static void dm_kill_unmapped_request(struct request *rq, int error)
}

/*
* Called with the clone's queue lock held (for non-blk-mq)
* Called with the clone's queue lock held (in the case of .request_fn)
*/
static void end_clone_request(struct request *clone, int error)
{
Expand Down Expand Up @@ -1857,22 +1857,22 @@ static int setup_clone(struct request *clone, struct request *rq,
return 0;
}

static struct request *clone_rq(struct request *rq, struct mapped_device *md,
struct dm_rq_target_io *tio, gfp_t gfp_mask)
static struct request *clone_old_rq(struct request *rq, struct mapped_device *md,
struct dm_rq_target_io *tio, gfp_t gfp_mask)
{
/*
* Create clone for use with .request_fn request_queue
*/
struct request *clone;

clone = alloc_clone_request(md, gfp_mask);
clone = alloc_old_clone_request(md, gfp_mask);
if (!clone)
return NULL;

blk_rq_init(NULL, clone);
if (setup_clone(clone, rq, tio, gfp_mask)) {
/* -ENOMEM */
free_clone_request(md, clone);
free_old_clone_request(md, clone);
return NULL;
}

Expand All @@ -1894,24 +1894,29 @@ static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
init_kthread_work(&tio->work, map_tio_request);
}

static struct dm_rq_target_io *prep_tio(struct request *rq,
struct mapped_device *md, gfp_t gfp_mask)
static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq,
struct mapped_device *md,
gfp_t gfp_mask)
{
struct dm_rq_target_io *tio;
int srcu_idx;
struct dm_table *table;

tio = alloc_rq_tio(md, gfp_mask);
tio = alloc_old_rq_tio(md, gfp_mask);
if (!tio)
return NULL;

init_tio(tio, rq, md);

table = dm_get_live_table(md, &srcu_idx);
/*
* Must clone a request if this .request_fn DM device
* is stacked on .request_fn device(s).
*/
if (!dm_table_mq_request_based(table)) {
if (!clone_rq(rq, md, tio, gfp_mask)) {
if (!clone_old_rq(rq, md, tio, gfp_mask)) {
dm_put_live_table(md, srcu_idx);
free_rq_tio(tio);
free_old_rq_tio(tio);
return NULL;
}
}
Expand All @@ -1923,7 +1928,7 @@ static struct dm_rq_target_io *prep_tio(struct request *rq,
/*
* Called with the queue lock held.
*/
static int dm_prep_fn(struct request_queue *q, struct request *rq)
static int dm_old_prep_fn(struct request_queue *q, struct request *rq)
{
struct mapped_device *md = q->queuedata;
struct dm_rq_target_io *tio;
Expand All @@ -1933,7 +1938,7 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
return BLKPREP_KILL;
}

tio = prep_tio(rq, md, GFP_ATOMIC);
tio = dm_old_prep_tio(rq, md, GFP_ATOMIC);
if (!tio)
return BLKPREP_DEFER;

Expand Down Expand Up @@ -2236,7 +2241,7 @@ static void dm_init_md_queue(struct mapped_device *md)
md->queue->backing_dev_info.congested_data = md;
}

static void dm_init_old_md_queue(struct mapped_device *md)
static void dm_init_normal_md_queue(struct mapped_device *md)
{
md->use_blk_mq = false;
dm_init_md_queue(md);
Expand Down Expand Up @@ -2503,7 +2508,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
* because request-based dm may be run just after the setting.
*/
if (dm_table_request_based(t)) {
stop_queue(q);
dm_stop_queue(q);
/*
* Leverage the fact that request-based DM targets are
* immutable singletons and establish md->immutable_target
Expand Down Expand Up @@ -2600,7 +2605,7 @@ struct queue_limits *dm_get_queue_limits(struct mapped_device *md)
}
EXPORT_SYMBOL_GPL(dm_get_queue_limits);

static void init_rq_based_worker_thread(struct mapped_device *md)
static void dm_old_init_rq_based_worker_thread(struct mapped_device *md)
{
/* Initialize the request-based DM worker thread */
init_kthread_worker(&md->kworker);
Expand All @@ -2609,9 +2614,9 @@ static void init_rq_based_worker_thread(struct mapped_device *md)
}

/*
* Fully initialize a request-based queue (->elevator, ->request_fn, etc).
* Fully initialize a .request_fn request-based queue.
*/
static int dm_init_request_based_queue(struct mapped_device *md)
static int dm_old_init_request_queue(struct mapped_device *md)
{
struct request_queue *q = NULL;

Expand All @@ -2624,11 +2629,11 @@ static int dm_init_request_based_queue(struct mapped_device *md)
md->seq_rq_merge_deadline_usecs = 0;

md->queue = q;
dm_init_old_md_queue(md);
dm_init_normal_md_queue(md);
blk_queue_softirq_done(md->queue, dm_softirq_done);
blk_queue_prep_rq(md->queue, dm_prep_fn);
blk_queue_prep_rq(md->queue, dm_old_prep_fn);

init_rq_based_worker_thread(md);
dm_old_init_rq_based_worker_thread(md);

elv_register_queue(md->queue);

Expand Down Expand Up @@ -2699,9 +2704,8 @@ static struct blk_mq_ops dm_mq_ops = {
.init_request = dm_mq_init_request,
};

static int dm_init_request_based_blk_mq_queue(struct mapped_device *md)
static int dm_mq_init_request_queue(struct mapped_device *md)
{
unsigned md_type = dm_get_md_type(md);
struct request_queue *q;
int err;

Expand Down Expand Up @@ -2766,21 +2770,21 @@ int dm_setup_md_queue(struct mapped_device *md)

switch (md_type) {
case DM_TYPE_REQUEST_BASED:
r = dm_init_request_based_queue(md);
r = dm_old_init_request_queue(md);
if (r) {
DMWARN("Cannot initialize queue for request-based mapped device");
DMERR("Cannot initialize queue for request-based mapped device");
return r;
}
break;
case DM_TYPE_MQ_REQUEST_BASED:
r = dm_init_request_based_blk_mq_queue(md);
r = dm_mq_init_request_queue(md);
if (r) {
DMWARN("Cannot initialize queue for request-based blk-mq mapped device");
DMERR("Cannot initialize queue for request-based dm-mq mapped device");
return r;
}
break;
case DM_TYPE_BIO_BASED:
dm_init_old_md_queue(md);
dm_init_normal_md_queue(md);
blk_queue_make_request(md->queue, dm_make_request);
/*
* DM handles splitting bios as needed. Free the bio_split bioset
Expand Down Expand Up @@ -3123,7 +3127,7 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
* dm defers requests to md->wq from md->queue.
*/
if (dm_request_based(md)) {
stop_queue(md->queue);
dm_stop_queue(md->queue);
if (md->kworker_task)
flush_kthread_worker(&md->kworker);
}
Expand All @@ -3147,7 +3151,7 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
dm_queue_flush(md);

if (dm_request_based(md))
start_queue(md->queue);
dm_start_queue(md->queue);

unlock_fs(md);
dm_table_presuspend_undo_targets(map);
Expand Down Expand Up @@ -3226,7 +3230,7 @@ static int __dm_resume(struct mapped_device *md, struct dm_table *map)
* Request-based dm is queueing the deferred I/Os in its request_queue.
*/
if (dm_request_based(md))
start_queue(md->queue);
dm_start_queue(md->queue);

unlock_fs(md);

Expand Down

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