block: move blk_mq_sched_assign_ioc to blk-ioc.c

Move blk_mq_sched_assign_ioc so that many interfaces from the file can
be marked static.  Rename the function to ioc_find_get_icq as well and
return the icq to simplify the interface.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-8-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-iosched.c

@@ -6666,7 +6666,7 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
  */
 static void bfq_prepare_request(struct request *rq)
 {
-	blk_mq_sched_assign_ioc(rq);
+	rq->elv.icq = ioc_find_get_icq(rq->q);
 
 	/*
 	 * Regardless of whether we have an icq attached, we have to

block/blk-ioc.c

@@ -24,7 +24,7 @@ static struct kmem_cache *iocontext_cachep;
  *
  * Increment reference count to @ioc.
  */
-void get_io_context(struct io_context *ioc)
+static void get_io_context(struct io_context *ioc)
 {
 	BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
 	atomic_long_inc(&ioc->refcount);
@@ -248,7 +248,8 @@ void ioc_clear_queue(struct request_queue *q)
 	__ioc_clear_queue(&icq_list);
 }
 
-int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
+static int create_task_io_context(struct task_struct *task, gfp_t gfp_flags,
+		int node)
 {
 	struct io_context *ioc;
 	int ret;
@@ -397,8 +398,8 @@ EXPORT_SYMBOL(ioc_lookup_icq);
  * The caller is responsible for ensuring @ioc won't go away and @q is
  * alive and will stay alive until this function returns.
  */
-struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
-			     gfp_t gfp_mask)
+static struct io_cq *ioc_create_icq(struct io_context *ioc,
+		struct request_queue *q, gfp_t gfp_mask)
 {
 	struct elevator_type *et = q->elevator->type;
 	struct io_cq *icq;
@@ -441,6 +442,36 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 	return icq;
 }
 
+struct io_cq *ioc_find_get_icq(struct request_queue *q)
+{
+	struct io_context *ioc;
+	struct io_cq *icq;
+
+	/* create task io_context, if we don't have one already */
+	if (unlikely(!current->io_context))
+		create_task_io_context(current, GFP_ATOMIC, q->node);
+
+	/*
+	 * May not have an IO context if it's a passthrough request
+	 */
+	ioc = current->io_context;
+	if (!ioc)
+		return NULL;
+
+	spin_lock_irq(&q->queue_lock);
+	icq = ioc_lookup_icq(ioc, q);
+	spin_unlock_irq(&q->queue_lock);
+
+	if (!icq) {
+		icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
+		if (!icq)
+			return NULL;
+	}
+	get_io_context(icq->ioc);
+	return icq;
+}
+EXPORT_SYMBOL_GPL(ioc_find_get_icq);
+
 static int __init blk_ioc_init(void)
 {
 	iocontext_cachep = kmem_cache_create("blkdev_ioc",

block/blk-mq-sched.c

@@ -18,37 +18,6 @@
 #include "blk-mq-tag.h"
 #include "blk-wbt.h"
 
-void blk_mq_sched_assign_ioc(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-	struct io_context *ioc;
-	struct io_cq *icq;
-
-	/* create task io_context, if we don't have one already */
-	if (unlikely(!current->io_context))
-		create_task_io_context(current, GFP_ATOMIC, q->node);
-
-	/*
-	 * May not have an IO context if it's a passthrough request
-	 */
-	ioc = current->io_context;
-	if (!ioc)
-		return;
-
-	spin_lock_irq(&q->queue_lock);
-	icq = ioc_lookup_icq(ioc, q);
-	spin_unlock_irq(&q->queue_lock);
-
-	if (!icq) {
-		icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
-		if (!icq)
-			return;
-	}
-	get_io_context(icq->ioc);
-	rq->elv.icq = icq;
-}
-EXPORT_SYMBOL_GPL(blk_mq_sched_assign_ioc);
-
 /*
  * Mark a hardware queue as needing a restart. For shared queues, maintain
  * a count of how many hardware queues are marked for restart.

block/blk-mq-sched.h

@@ -8,8 +8,6 @@
 
 #define MAX_SCHED_RQ (16 * BLKDEV_DEFAULT_RQ)
 
-void blk_mq_sched_assign_ioc(struct request *rq);
-
 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
 		unsigned int nr_segs, struct request **merged_request);
 bool blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,

block/blk.h

@@ -363,14 +363,10 @@ static inline unsigned int bio_aligned_discard_max_sectors(
 /*
  * Internal io_context interface
  */
-void get_io_context(struct io_context *ioc);
+struct io_cq *ioc_find_get_icq(struct request_queue *q);
 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
-struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
-			     gfp_t gfp_mask);
 void ioc_clear_queue(struct request_queue *q);
 
-int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
-
 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
 extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,