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dm: fix request-based DM to not bounce through indirect dm_submit_bio

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It is unnecessary to force request-based DM to call into bio-based
dm_submit_bio (via indirect disk->fops->submit_bio) only to have it then
call blk_mq_submit_bio().

Fix this by establishing a request-based DM block_device_operations
(dm_rq_blk_dops, which doesn't have .submit_bio) and update
dm_setup_md_queue() to set md->disk->fops to it for
DM_TYPE_REQUEST_BASED.

Remove DM_TYPE_REQUEST_BASED conditional in dm_submit_bio and unexport
blk_mq_submit_bio.

Fixes: c62b37d96b ("block: move ->make_request_fn to struct block_device_operations")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2020-10-07 16:41:01 -04:00
parent 9c37de297f
commit 681cc5e866
2 changed files with 12 additions and 14 deletions
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1
block/blk-mq.c
View File

@ -2265,7 +2265,6 @@ queue_exit:
blk_queue_exit(q);
return BLK_QC_T_NONE;
}
EXPORT_SYMBOL_GPL(blk_mq_submit_bio); /* only for request based dm */
void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx)

25
drivers/md/dm.c
View File

@ -1633,18 +1633,6 @@ static blk_qc_t dm_submit_bio(struct bio *bio)
int srcu_idx;
struct dm_table *map;
if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {
/*
* We are called with a live reference on q_usage_counter, but
* that one will be released as soon as we return. Grab an
* extra one as blk_mq_submit_bio expects to be able to consume
* a reference (which lives until the request is freed in case a
* request is allocated).
*/
percpu_ref_get(&bio->bi_disk->queue->q_usage_counter);
return blk_mq_submit_bio(bio);
}
map = dm_get_live_table(md, &srcu_idx);
if (unlikely(!map)) {
DMERR_LIMIT("%s: mapping table unavailable, erroring io",
@ -1727,6 +1715,7 @@ static int next_free_minor(int *minor)
}
static const struct block_device_operations dm_blk_dops;
static const struct block_device_operations dm_rq_blk_dops;
static const struct dax_operations dm_dax_ops;
static void dm_wq_work(struct work_struct *work);
@ -2113,9 +2102,10 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
switch (type) {
case DM_TYPE_REQUEST_BASED:
md->disk->fops = &dm_rq_blk_dops;
r = dm_mq_init_request_queue(md, t);
if (r) {
DMERR("Cannot initialize queue for request-based dm-mq mapped device");
DMERR("Cannot initialize queue for request-based dm mapped device");
return r;
}
break;
@ -3095,6 +3085,15 @@ static const struct block_device_operations dm_blk_dops = {
.owner = THIS_MODULE
};
static const struct block_device_operations dm_rq_blk_dops = {
.open = dm_blk_open,
.release = dm_blk_close,
.ioctl = dm_blk_ioctl,
.getgeo = dm_blk_getgeo,
.pr_ops = &dm_pr_ops,
.owner = THIS_MODULE
};
static const struct dax_operations dm_dax_ops = {
.direct_access = dm_dax_direct_access,
.dax_supported = dm_dax_supported,