[PATCH v3 05/12] block/cgroup: Inline blkg_conf_{open,close}_bdev_frozen()

[Bart Van Assche <bvanassche@acm.org>]

The blkg_conf_open_bdev_frozen() calling convention is not compatible
with lock context annotations. Inline both blkg_conf_open_bdev_frozen()
and blkg_conf_close_bdev_frozen() because these functions only have a
single caller. This patch prepares for enabling lock context analysis.

The type of 'memflags' has been changed from unsigned long into unsigned
int to match the type of current->flags. See also <linux/sched.h>.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-cgroup.c | 46 ----------------------------------------------
 block/blk-cgroup.h |  4 ----
 block/blk-iocost.c | 29 +++++++++++++++++++++++------
 3 files changed, 23 insertions(+), 56 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 86513c54c217..de0f753b8fe5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -812,39 +812,6 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 }
 EXPORT_SYMBOL_GPL(blkg_conf_open_bdev);
 
-/*
- * Similar to blkg_conf_open_bdev, but additionally freezes the queue,
- * ensures the correct locking order between freeze queue and q->rq_qos_mutex.
- *
- * This function returns negative error on failure. On success it returns
- * memflags which must be saved and later passed to
- * blkg_conf_close_bdev_frozen() for restoring the memalloc scope.
- */
-unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
-{
-	int ret;
-	unsigned long memflags;
-
-	if (ctx->bdev)
-		return -EINVAL;
-
-	ret = blkg_conf_open_bdev(ctx);
-	if (ret < 0)
-		return ret;
-	/*
-	 * At this point, we haven’t started protecting anything related to QoS,
-	 * so we release q->rq_qos_mutex here, which was first acquired in blkg_
-	 * conf_open_bdev. Later, we re-acquire q->rq_qos_mutex after freezing
-	 * the queue to maintain the correct locking order.
-	 */
-	mutex_unlock(&ctx->bdev->bd_queue->rq_qos_mutex);
-
-	memflags = blk_mq_freeze_queue(ctx->bdev->bd_queue);
-	mutex_lock(&ctx->bdev->bd_queue->rq_qos_mutex);
-
-	return memflags;
-}
-
 /**
  * blkg_conf_prep - parse and prepare for per-blkg config update
  * @blkcg: target block cgroup
@@ -991,19 +958,6 @@ void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
 }
 EXPORT_SYMBOL_GPL(blkg_conf_close_bdev);
 
-/*
- * Similar to blkg_close_bdev, but also unfreezes the queue. Should be used
- * when blkg_conf_open_bdev_frozen is used to open the bdev.
- */
-void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
-				 unsigned long memflags)
-{
-	struct request_queue *q = ctx->bdev->bd_queue;
-
-	blkg_conf_close_bdev(ctx);
-	blk_mq_unfreeze_queue(q, memflags);
-}
-
 static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src)
 {
 	int i;
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index f0a3af520c55..f25fecb87c43 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -220,7 +220,6 @@ struct blkg_conf_ctx {
 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
 int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 	__cond_acquires(0, &ctx->bdev->bd_queue->rq_qos_mutex);
-unsigned long blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx);
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		   struct blkg_conf_ctx *ctx)
 	__cond_acquires(0, &ctx->bdev->bd_disk->queue->queue_lock);
@@ -228,9 +227,6 @@ void blkg_conf_unprep(struct blkg_conf_ctx *ctx)
 	__releases(ctx->bdev->bd_disk->queue->queue_lock);
 void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
 	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
-void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
-				 unsigned long memflags)
-	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
 
 /**
  * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index e611dd63d712..353c165c5cd4 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3233,19 +3233,30 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 			     size_t nbytes, loff_t off)
 {
 	struct blkg_conf_ctx ctx;
+	struct request_queue *q;
 	struct gendisk *disk;
 	struct ioc *ioc;
 	u32 qos[NR_QOS_PARAMS];
 	bool enable, user;
 	char *body, *p;
-	unsigned long memflags;
+	unsigned int memflags;
 	int ret;
 
 	blkg_conf_init(&ctx, input);
 
-	memflags = blkg_conf_open_bdev_frozen(&ctx);
-	if (IS_ERR_VALUE(memflags))
-		return memflags;
+	ret = blkg_conf_open_bdev(&ctx);
+	if (ret)
+		return ret;
+	/*
+	 * At this point, we haven’t started protecting anything related to QoS,
+	 * so we release q->rq_qos_mutex here, which was first acquired in blkg_
+	 * conf_open_bdev. Later, we re-acquire q->rq_qos_mutex after freezing
+	 * the queue to maintain the correct locking order.
+	 */
+	mutex_unlock(&ctx.bdev->bd_queue->rq_qos_mutex);
+
+	memflags = blk_mq_freeze_queue(ctx.bdev->bd_queue);
+	mutex_lock(&ctx.bdev->bd_queue->rq_qos_mutex);
 
 	body = ctx.body;
 	disk = ctx.bdev->bd_disk;
@@ -3362,14 +3373,20 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 
 	blk_mq_unquiesce_queue(disk->queue);
 
-	blkg_conf_close_bdev_frozen(&ctx, memflags);
+	q = ctx.bdev->bd_queue;
+	blkg_conf_close_bdev(&ctx);
+	blk_mq_unfreeze_queue(q, memflags);
+
 	return nbytes;
+
 einval:
 	spin_unlock_irq(&ioc->lock);
 	blk_mq_unquiesce_queue(disk->queue);
 	ret = -EINVAL;
 err:
-	blkg_conf_close_bdev_frozen(&ctx, memflags);
+	q = ctx.bdev->bd_queue;
+	blkg_conf_close_bdev(&ctx);
+	blk_mq_unfreeze_queue(q, memflags);
 	return ret;
 }