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| author |   Mikulas Patocka <mpatocka@redhat.com> | 2018-11-06 22:34:59 +0100 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@redhat.com> | 2018-12-18 09:02:25 -0500 |
| commit | 24113d4878439baf1f23c1a33dfcc340fba66e97 (patch) | |
| tree | 8a5111ada71d026b290b7c009e79b28c99fbcdf5 /drivers/md/dm.c | |
| parent | blk-mq: enable IO poll if .nr_queues of type poll > 0 (diff) | |
| download | linux-dev-24113d4878439baf1f23c1a33dfcc340fba66e97.tar.xz linux-dev-24113d4878439baf1f23c1a33dfcc340fba66e97.zip | |
dm: avoid indirect call in __dm_make_request
Indirect calls are inefficient because of retpolines that are used for
spectre workaround. This patch replaces an indirect call with a condition
(that can be predicted by the branch predictor).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 29 |
1 files changed, 6 insertions, 23 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index dddbca63e140..fa70c90e6757 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1696,10 +1696,7 @@ out: return ret; } -typedef blk_qc_t (process_bio_fn)(struct mapped_device *, struct dm_table *, struct bio *); - -static blk_qc_t __dm_make_request(struct request_queue *q, struct bio *bio, - process_bio_fn process_bio) +static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio) { struct mapped_device *md = q->queuedata; blk_qc_t ret = BLK_QC_T_NONE; @@ -1719,26 +1716,15 @@ static blk_qc_t __dm_make_request(struct request_queue *q, struct bio *bio, return ret; } - ret = process_bio(md, map, bio); + if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED) + ret = __process_bio(md, map, bio); + else + ret = __split_and_process_bio(md, map, bio); dm_put_live_table(md, srcu_idx); return ret; } -/* - * The request function that remaps the bio to one target and - * splits off any remainder. - */ -static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio) -{ - return __dm_make_request(q, bio, __split_and_process_bio); -} - -static blk_qc_t dm_make_request_nvme(struct request_queue *q, struct bio *bio) -{ - return __dm_make_request(q, bio, __process_bio); -} - static int dm_any_congested(void *congested_data, int bdi_bits) { int r = bdi_bits; @@ -2229,12 +2215,9 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) break; case DM_TYPE_BIO_BASED: case DM_TYPE_DAX_BIO_BASED: - dm_init_normal_md_queue(md); - blk_queue_make_request(md->queue, dm_make_request); - break; case DM_TYPE_NVME_BIO_BASED: dm_init_normal_md_queue(md); - blk_queue_make_request(md->queue, dm_make_request_nvme); + blk_queue_make_request(md->queue, dm_make_request); break; case DM_TYPE_NONE: WARN_ON_ONCE(true); |