block: don't protect generic_make_request_checks with blk_queue_enter

Now a063057d7c73 ("block: Fix a race between request queue removal and
the block cgroup controller") has been reverted, and blkcg_exit_queue()
won't be called in blk_cleanup_queue() any more.

So don't need to protect generic_make_request_checks() with
blk_queue_enter(), then the total mess can be cleaned.

37f9579f4c31 ("blk-mq: Avoid that submitting a bio concurrently with device
removal triggers a crash") is reverted.

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

diff --git a/block/blk-core.c b/block/blk-core.c
index 25faab0..e6a273d 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -957,22 +957,8 @@ blk_qc_t generic_make_request(struct bio *bio)
         * yet.
         */
        struct bio_list bio_list_on_stack[2];
-       blk_mq_req_flags_t flags = 0;
-       struct request_queue *q = bio->bi_disk->queue;
        blk_qc_t ret = BLK_QC_T_NONE;
 
-       if (bio->bi_opf & REQ_NOWAIT)
-               flags = BLK_MQ_REQ_NOWAIT;
-       if (bio_flagged(bio, BIO_QUEUE_ENTERED))
-               blk_queue_enter_live(q);
-       else if (blk_queue_enter(q, flags) < 0) {
-               if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
-                       bio_wouldblock_error(bio);
-               else
-                       bio_io_error(bio);
-               return ret;
-       }
-
        if (!generic_make_request_checks(bio))
                goto out;
 
@@ -1009,22 +995,11 @@ blk_qc_t generic_make_request(struct bio *bio)
        bio_list_init(&bio_list_on_stack[0]);
        current->bio_list = bio_list_on_stack;
        do {
-               bool enter_succeeded = true;
-
-               if (unlikely(q != bio->bi_disk->queue)) {
-                       if (q)
-                               blk_queue_exit(q);
-                       q = bio->bi_disk->queue;
-                       flags = 0;
-                       if (bio->bi_opf & REQ_NOWAIT)
-                               flags = BLK_MQ_REQ_NOWAIT;
-                       if (blk_queue_enter(q, flags) < 0) {
-                               enter_succeeded = false;
-                               q = NULL;
-                       }
-               }
+               struct request_queue *q = bio->bi_disk->queue;
+               blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ?
+                       BLK_MQ_REQ_NOWAIT : 0;
 
-               if (enter_succeeded) {
+               if (likely(blk_queue_enter(q, flags) == 0)) {
                        struct bio_list lower, same;
 
                        /* Create a fresh bio_list for all subordinate requests */
@@ -1032,6 +1007,8 @@ blk_qc_t generic_make_request(struct bio *bio)
                        bio_list_init(&bio_list_on_stack[0]);
                        ret = q->make_request_fn(q, bio);
 
+                       blk_queue_exit(q);
+
                        /* sort new bios into those for a lower level
                         * and those for the same level
                         */
@@ -1058,8 +1035,6 @@ blk_qc_t generic_make_request(struct bio *bio)
        current->bio_list = NULL; /* deactivate */
 
 out:
-       if (q)
-               blk_queue_exit(q);
        return ret;
 }
 EXPORT_SYMBOL(generic_make_request);