Commit fe662860 authored by Nilay Shroff's avatar Nilay Shroff Committed by Jens Axboe
Browse files

block: get rid of request queue ->sysfs_dir_lock 



The request queue uses ->sysfs_dir_lock for protecting the addition/
deletion of kobject entries under sysfs while we register/unregister
blk-mq. However kobject addition/deletion is already protected with
kernfs/sysfs internal synchronization primitives. So use of q->sysfs_
dir_lock seems redundant.

Moreover, q->sysfs_dir_lock is also used at few other callsites along
with q->sysfs_lock for protecting the addition/deletion of kojects.
One such example is when we register with sysfs a set of independent
access ranges for a disk. Here as well we could get rid off q->sysfs_
dir_lock and only use q->sysfs_lock.

The only variable which q->sysfs_dir_lock appears to protect is q->
mq_sysfs_init_done which is set/unset while registering/unregistering
blk-mq with sysfs. But use of q->mq_sysfs_init_done could be easily
replaced using queue registered bit QUEUE_FLAG_REGISTERED.

So with this patch we remove q->sysfs_dir_lock from each callsite
and replace q->mq_sysfs_init_done using QUEUE_FLAG_REGISTERED.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20250128143436.874357-2-nilay@linux.ibm.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5aa21b04

block/blk-core.c

+0 −1
Original line number Diff line number Diff line
@@ -430,7 +430,6 @@ struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id) 
	refcount_set(&q->refs, 1);

	mutex_init(&q->debugfs_mutex);

	mutex_init(&q->sysfs_lock);

	mutex_init(&q->sysfs_dir_lock);

	mutex_init(&q->limits_lock);

	mutex_init(&q->rq_qos_mutex);

	spin_lock_init(&q->queue_lock);

block/blk-ia-ranges.c

+0 −4
Original line number Diff line number Diff line
@@ -111,7 +111,6 @@ int disk_register_independent_access_ranges(struct gendisk *disk) 
	struct request_queue *q = disk->queue;

	int i, ret;



	lockdep_assert_held(&q->sysfs_dir_lock);

	lockdep_assert_held(&q->sysfs_lock);



	if (!iars)
@@ -155,7 +154,6 @@ void disk_unregister_independent_access_ranges(struct gendisk *disk) 
	struct blk_independent_access_ranges *iars = disk->ia_ranges;

	int i;



	lockdep_assert_held(&q->sysfs_dir_lock);

	lockdep_assert_held(&q->sysfs_lock);



	if (!iars)
@@ -289,7 +287,6 @@ void disk_set_independent_access_ranges(struct gendisk *disk, 
{

	struct request_queue *q = disk->queue;



	mutex_lock(&q->sysfs_dir_lock);

	mutex_lock(&q->sysfs_lock);

	if (iars && !disk_check_ia_ranges(disk, iars)) {

		kfree(iars);
@@ -313,6 +310,5 @@ void disk_set_independent_access_ranges(struct gendisk *disk, 
		disk_register_independent_access_ranges(disk);

unlock:

	mutex_unlock(&q->sysfs_lock);

	mutex_unlock(&q->sysfs_dir_lock);

}

EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);

block/blk-mq-sysfs.c

+5 −18
Original line number Diff line number Diff line
@@ -223,8 +223,6 @@ int blk_mq_sysfs_register(struct gendisk *disk) 
	unsigned long i, j;

	int ret;



	lockdep_assert_held(&q->sysfs_dir_lock);



	ret = kobject_add(q->mq_kobj, &disk_to_dev(disk)->kobj, "mq");

	if (ret < 0)

		goto out;
@@ -237,7 +235,6 @@ int blk_mq_sysfs_register(struct gendisk *disk) 
			goto unreg;

	}



	q->mq_sysfs_init_done = true;



out:

	return ret;
@@ -259,15 +256,12 @@ void blk_mq_sysfs_unregister(struct gendisk *disk) 
	struct blk_mq_hw_ctx *hctx;

	unsigned long i;



	lockdep_assert_held(&q->sysfs_dir_lock);



	queue_for_each_hw_ctx(q, hctx, i)

		blk_mq_unregister_hctx(hctx);



	kobject_uevent(q->mq_kobj, KOBJ_REMOVE);

	kobject_del(q->mq_kobj);



	q->mq_sysfs_init_done = false;

}



void blk_mq_sysfs_unregister_hctxs(struct request_queue *q)
@@ -275,15 +269,11 @@ void blk_mq_sysfs_unregister_hctxs(struct request_queue *q) 
	struct blk_mq_hw_ctx *hctx;

	unsigned long i;



	mutex_lock(&q->sysfs_dir_lock);

	if (!q->mq_sysfs_init_done)

		goto unlock;

	if (!blk_queue_registered(q))

		return;



	queue_for_each_hw_ctx(q, hctx, i)

		blk_mq_unregister_hctx(hctx);



unlock:

	mutex_unlock(&q->sysfs_dir_lock);

}



int blk_mq_sysfs_register_hctxs(struct request_queue *q)
@@ -292,9 +282,8 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q) 
	unsigned long i;

	int ret = 0;



	mutex_lock(&q->sysfs_dir_lock);

	if (!q->mq_sysfs_init_done)

		goto unlock;

	if (!blk_queue_registered(q))

		goto out;



	queue_for_each_hw_ctx(q, hctx, i) {

		ret = blk_mq_register_hctx(hctx);
@@ -302,8 +291,6 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q) 
			break;

	}



unlock:

	mutex_unlock(&q->sysfs_dir_lock);



out:

	return ret;

}

block/blk-sysfs.c

+0 −5
Original line number Diff line number Diff line
@@ -764,7 +764,6 @@ int blk_register_queue(struct gendisk *disk) 
	struct request_queue *q = disk->queue;

	int ret;



	mutex_lock(&q->sysfs_dir_lock);

	kobject_init(&disk->queue_kobj, &blk_queue_ktype);

	ret = kobject_add(&disk->queue_kobj, &disk_to_dev(disk)->kobj, "queue");

	if (ret < 0)
@@ -805,7 +804,6 @@ int blk_register_queue(struct gendisk *disk) 
	if (q->elevator)

		kobject_uevent(&q->elevator->kobj, KOBJ_ADD);

	mutex_unlock(&q->sysfs_lock);

	mutex_unlock(&q->sysfs_dir_lock);



	/*

	 * SCSI probing may synchronously create and destroy a lot of
@@ -830,7 +828,6 @@ int blk_register_queue(struct gendisk *disk) 
	mutex_unlock(&q->sysfs_lock);

out_put_queue_kobj:

	kobject_put(&disk->queue_kobj);

	mutex_unlock(&q->sysfs_dir_lock);

	return ret;

}
@@ -861,7 +858,6 @@ void blk_unregister_queue(struct gendisk *disk) 
	blk_queue_flag_clear(QUEUE_FLAG_REGISTERED, q);

	mutex_unlock(&q->sysfs_lock);



	mutex_lock(&q->sysfs_dir_lock);

	/*

	 * Remove the sysfs attributes before unregistering the queue data

	 * structures that can be modified through sysfs.
@@ -878,7 +874,6 @@ void blk_unregister_queue(struct gendisk *disk) 
	/* Now that we've deleted all child objects, we can delete the queue. */

	kobject_uevent(&disk->queue_kobj, KOBJ_REMOVE);

	kobject_del(&disk->queue_kobj);

	mutex_unlock(&q->sysfs_dir_lock);



	blk_debugfs_remove(disk);

}

include/linux/blkdev.h

+0 −3
Original line number Diff line number Diff line
@@ -561,7 +561,6 @@ struct request_queue { 
	struct list_head	flush_list;



	struct mutex		sysfs_lock;

	struct mutex		sysfs_dir_lock;

	struct mutex		limits_lock;



	/*
@@ -605,8 +604,6 @@ struct request_queue { 
	 * Serializes all debugfs metadata operations using the above dentries.

	 */

	struct mutex		debugfs_mutex;



	bool			mq_sysfs_init_done;

};



/* Keep blk_queue_flag_name[] in sync with the definitions below */