blk-mq-sched: refactor scheduler initialization

Preparation cleanup for the next couple of fixes, push
blk_mq_sched_setup() and e->ops.mq.init_sched() into a helper.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index fc00f00898d34f5338933386eb08831601383f7f..6bd1758ea29b4a071a4cc5addd44318d6b539fee 100644 (file)
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -432,11 +432,45 @@ static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
        }
 }
 
-int blk_mq_sched_setup(struct request_queue *q)
+static int blk_mq_sched_alloc_tags(struct request_queue *q,
+                                  struct blk_mq_hw_ctx *hctx,
+                                  unsigned int hctx_idx)
+{
+       struct blk_mq_tag_set *set = q->tag_set;
+       int ret;
+
+       hctx->sched_tags = blk_mq_alloc_rq_map(set, hctx_idx, q->nr_requests,
+                                              set->reserved_tags);
+       if (!hctx->sched_tags)
+               return -ENOMEM;
+
+       ret = blk_mq_alloc_rqs(set, hctx->sched_tags, hctx_idx, q->nr_requests);
+       if (ret)
+               blk_mq_sched_free_tags(set, hctx, hctx_idx);
+
+       return ret;
+}
+
+void blk_mq_sched_teardown(struct request_queue *q)
 {
        struct blk_mq_tag_set *set = q->tag_set;
        struct blk_mq_hw_ctx *hctx;
-       int ret, i;
+       int i;
+
+       queue_for_each_hw_ctx(q, hctx, i)
+               blk_mq_sched_free_tags(set, hctx, i);
+}
+
+int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
+{
+       struct blk_mq_hw_ctx *hctx;
+       unsigned int i;
+       int ret;
+
+       if (!e) {
+               q->elevator = NULL;
+               return 0;
+       }
 
        /*
         * Default to 256, since we don't split into sync/async like the
@@ -444,49 +478,21 @@ int blk_mq_sched_setup(struct request_queue *q)
         */
        q->nr_requests = 2 * BLKDEV_MAX_RQ;
 
-       /*
-        * We're switching to using an IO scheduler, so setup the hctx
-        * scheduler tags and switch the request map from the regular
-        * tags to scheduler tags. First allocate what we need, so we
-        * can safely fail and fallback, if needed.
-        */
-       ret = 0;
        queue_for_each_hw_ctx(q, hctx, i) {
-               hctx->sched_tags = blk_mq_alloc_rq_map(set, i,
-                               q->nr_requests, set->reserved_tags);
-               if (!hctx->sched_tags) {
-                       ret = -ENOMEM;
-                       break;
-               }
-               ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
+               ret = blk_mq_sched_alloc_tags(q, hctx, i);
                if (ret)
-                       break;
+                       goto err;
        }
 
-       /*
-        * If we failed, free what we did allocate
-        */
-       if (ret) {
-               queue_for_each_hw_ctx(q, hctx, i) {
-                       if (!hctx->sched_tags)
-                               continue;
-                       blk_mq_sched_free_tags(set, hctx, i);
-               }
-
-               return ret;
-       }
+       ret = e->ops.mq.init_sched(q, e);
+       if (ret)
+               goto err;
 
        return 0;
-}
 
-void blk_mq_sched_teardown(struct request_queue *q)
-{
-       struct blk_mq_tag_set *set = q->tag_set;
-       struct blk_mq_hw_ctx *hctx;
-       int i;
-
-       queue_for_each_hw_ctx(q, hctx, i)
-               blk_mq_sched_free_tags(set, hctx, i);
+err:
+       blk_mq_sched_teardown(q);
+       return ret;
 }
 
 int blk_mq_sched_init(struct request_queue *q)

diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index a75b16b123f7aadac672651a7eef5c79f5553e16..873f9af5a35bebd57f9a83555cda6461aa9b6990 100644 (file)
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -32,7 +32,7 @@ void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
                        struct list_head *rq_list,
                        struct request *(*get_rq)(struct blk_mq_hw_ctx *));
 
-int blk_mq_sched_setup(struct request_queue *q);
+int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
 void blk_mq_sched_teardown(struct request_queue *q);
 
 int blk_mq_sched_init(struct request_queue *q);

diff --git a/block/elevator.c b/block/elevator.c
index 01139f549b5be73047f346153f5b8fedcb23b3d0..f236ef1d2be9922dc17450b69a4328dc82c12cbd 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -242,17 +242,12 @@ int elevator_init(struct request_queue *q, char *name)
                }
        }
 
-       if (e->uses_mq) {
-               err = blk_mq_sched_setup(q);
-               if (!err)
-                       err = e->ops.mq.init_sched(q, e);
-       } else
+       if (e->uses_mq)
+               err = blk_mq_init_sched(q, e);
+       else
                err = e->ops.sq.elevator_init_fn(q, e);
-       if (err) {
-               if (e->uses_mq)
-                       blk_mq_sched_teardown(q);
+       if (err)
                elevator_put(e);
-       }
        return err;
 }
 EXPORT_SYMBOL(elevator_init);
@@ -987,21 +982,18 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
        }
 
        /* allocate, init and register new elevator */
-       if (new_e) {
-               if (new_e->uses_mq) {
-                       err = blk_mq_sched_setup(q);
-                       if (!err)
-                               err = new_e->ops.mq.init_sched(q, new_e);
-               } else
-                       err = new_e->ops.sq.elevator_init_fn(q, new_e);
-               if (err)
-                       goto fail_init;
+       if (q->mq_ops)
+               err = blk_mq_init_sched(q, new_e);
+       else
+               err = new_e->ops.sq.elevator_init_fn(q, new_e);
+       if (err)
+               goto fail_init;
 
+       if (new_e) {
                err = elv_register_queue(q);
                if (err)
                        goto fail_register;
-       } else
-               q->elevator = NULL;
+       }
 
        /* done, kill the old one and finish */
        if (old) {