blk-mq: remove blk_mq_put_ctx()

No code that occurs between blk_mq_get_ctx() and blk_mq_put_ctx() depends
on preemption being disabled for its correctness. Since removing the CPU
preemption calls does not measurably affect performance, simplify the
blk-mq code by removing the blk_mq_put_ctx() function and also by not
disabling preemption in blk_mq_get_ctx().

Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 4 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 956a7aa9a637..c9d183d6c499 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -330,10 +330,8 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
         bool ret = false;
         enum hctx_type type;
 
-        if (e && e->type->ops.bio_merge) {
-                blk_mq_put_ctx(ctx);
+        if (e && e->type->ops.bio_merge)
                 return e->type->ops.bio_merge(hctx, bio, nr_segs);
-        }
 
         type = hctx->type;
         if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
@@ -344,7 +342,6 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
                 spin_unlock(&ctx->lock);
         }
 
-        blk_mq_put_ctx(ctx);
         return ret;
 }