diff options
| author | Christoph Hellwig <hch@lst.de> | 2020-04-25 09:53:36 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-04-25 09:45:44 -0600 |
| commit | 8cf7961dab42c9177a556b719c15f5b9449c24d1 (patch) | |
| tree | cf0e7e5d0b7f6f0ee665629b61fc91cc56ed77c7 /block | |
| parent | ae3cc8d8ff061d3ffca96665685550e70a86472a (diff) | |
block: bypass ->make_request_fn for blk-mq drivers
Call blk_mq_make_request when no ->make_request_fn is set. This is
safe now that blk_alloc_queue always sets up the pointer for make_request
based drivers. This avoids an indirect call in the blk-mq driver I/O
fast path, which is rather expensive due to spectre mitigations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-core.c | 26 | ||||
| -rw-r--r-- | block/blk-mq.c | 4 |
2 files changed, 19 insertions, 11 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 38e984d95e84..dffff2100888 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1073,7 +1073,10 @@ blk_qc_t generic_make_request(struct bio *bio) /* Create a fresh bio_list for all subordinate requests */ bio_list_on_stack[1] = bio_list_on_stack[0]; bio_list_init(&bio_list_on_stack[0]); - ret = q->make_request_fn(q, bio); + if (q->make_request_fn) + ret = q->make_request_fn(q, bio); + else + ret = blk_mq_make_request(q, bio); blk_queue_exit(q); @@ -1113,9 +1116,7 @@ EXPORT_SYMBOL(generic_make_request); * * This function behaves like generic_make_request(), but does not protect * against recursion. Must only be used if the called driver is known - * to not call generic_make_request (or direct_make_request) again from - * its make_request function. (Calling direct_make_request again from - * a workqueue is perfectly fine as that doesn't recurse). + * to be blk-mq based. */ blk_qc_t direct_make_request(struct bio *bio) { @@ -1123,20 +1124,27 @@ blk_qc_t direct_make_request(struct bio *bio) bool nowait = bio->bi_opf & REQ_NOWAIT; blk_qc_t ret; + if (WARN_ON_ONCE(q->make_request_fn)) + goto io_error; if (!generic_make_request_checks(bio)) return BLK_QC_T_NONE; if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { if (nowait && !blk_queue_dying(q)) - bio_wouldblock_error(bio); - else - bio_io_error(bio); - return BLK_QC_T_NONE; + goto would_block; + goto io_error; } - ret = q->make_request_fn(q, bio); + ret = blk_mq_make_request(q, bio); blk_queue_exit(q); return ret; + +would_block: + bio_wouldblock_error(bio); + return BLK_QC_T_NONE; +io_error: + bio_io_error(bio); + return BLK_QC_T_NONE; } EXPORT_SYMBOL_GPL(direct_make_request); diff --git a/block/blk-mq.c b/block/blk-mq.c index 71d0894ce1c5..bcc3a2397d4a 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1984,7 +1984,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq) * * Returns: Request queue cookie. */ -static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) +blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) { const int is_sync = op_is_sync(bio->bi_opf); const int is_flush_fua = op_is_flush(bio->bi_opf); @@ -2096,6 +2096,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) return cookie; } +EXPORT_SYMBOL_GPL(blk_mq_make_request); /* 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) @@ -2955,7 +2956,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, INIT_LIST_HEAD(&q->requeue_list); spin_lock_init(&q->requeue_lock); - q->make_request_fn = blk_mq_make_request; q->nr_requests = set->queue_depth; /* |