From b5bd357cf8b65d31e32b1668293cbeedb6c06334 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Fri, 19 Jun 2020 20:47:23 +0000 Subject: block: add docs for gendisk / request_queue refcount helpers This adds documentation for the gendisk / request_queue refcount helpers. Signed-off-by: Luis Chamberlain Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- block/blk-core.c | 13 +++++++++++++ block/genhd.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 62 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 03252af8c82c..13777c0c97f0 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -321,6 +321,13 @@ void blk_clear_pm_only(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_clear_pm_only); +/** + * blk_put_queue - decrement the request_queue refcount + * @q: the request_queue structure to decrement the refcount for + * + * Decrements the refcount of the request_queue kobject. When this reaches 0 + * we'll have blk_release_queue() called. + */ void blk_put_queue(struct request_queue *q) { kobject_put(&q->kobj); @@ -598,6 +605,12 @@ struct request_queue *blk_alloc_queue(make_request_fn make_request, int node_id) } EXPORT_SYMBOL(blk_alloc_queue); +/** + * blk_get_queue - increment the request_queue refcount + * @q: the request_queue structure to increment the refcount for + * + * Increment the refcount of the request_queue kobject. + */ bool blk_get_queue(struct request_queue *q) { if (likely(!blk_queue_dying(q))) { diff --git a/block/genhd.c b/block/genhd.c index 1a7659327664..f741613d731f 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -876,6 +876,20 @@ static void invalidate_partition(struct gendisk *disk, int partno) bdput(bdev); } +/** + * del_gendisk - remove the gendisk + * @disk: the struct gendisk to remove + * + * Removes the gendisk and all its associated resources. This deletes the + * partitions associated with the gendisk, and unregisters the associated + * request_queue. + * + * This is the counter to the respective __device_add_disk() call. + * + * The final removal of the struct gendisk happens when its refcount reaches 0 + * with put_disk(), which should be called after del_gendisk(), if + * __device_add_disk() was used. + */ void del_gendisk(struct gendisk *disk) { struct disk_part_iter piter; @@ -1514,6 +1528,23 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno) return 0; } +/** + * disk_release - releases all allocated resources of the gendisk + * @dev: the device representing this disk + * + * This function releases all allocated resources of the gendisk. + * + * The struct gendisk refcount is incremented with get_gendisk() or + * get_disk_and_module(), and its refcount is decremented with + * put_disk_and_module() or put_disk(). Once the refcount reaches 0 this + * function is called. + * + * Drivers which used __device_add_disk() have a gendisk with a request_queue + * assigned. Since the request_queue sits on top of the gendisk for these + * drivers we also call blk_put_queue() for them, and we expect the + * request_queue refcount to reach 0 at this point, and so the request_queue + * will also be freed prior to the disk. + */ static void disk_release(struct device *dev) { struct gendisk *disk = dev_to_disk(dev); @@ -1727,6 +1758,13 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) } EXPORT_SYMBOL(__alloc_disk_node); +/** + * get_disk_and_module - increments the gendisk and gendisk fops module refcount + * @disk: the struct gendisk to to increment the refcount for + * + * This increments the refcount for the struct gendisk, and the gendisk's + * fops module owner. + */ struct kobject *get_disk_and_module(struct gendisk *disk) { struct module *owner; @@ -1747,6 +1785,13 @@ struct kobject *get_disk_and_module(struct gendisk *disk) } EXPORT_SYMBOL(get_disk_and_module); +/** + * put_disk - decrements the gendisk refcount + * @disk: the struct gendisk to to decrement the refcount for + * + * This decrements the refcount for the struct gendisk. When this reaches 0 + * we'll have disk_release() called. + */ void put_disk(struct gendisk *disk) { if (disk) @@ -1754,7 +1799,10 @@ void put_disk(struct gendisk *disk) } EXPORT_SYMBOL(put_disk); -/* +/** + * put_disk_and_module - decrements the module and gendisk refcount + * @disk: the struct gendisk to to decrement the refcount for + * * This is a counterpart of get_disk_and_module() and thus also of * get_gendisk(). */ -- cgit v1.2.3