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    Subject[PATCH v5 1/7] block: add docs for gendisk / request_queue refcount helpers
    Date
    This adds documentation for the gendisk / request_queue refcount
    helpers.

    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Reviewed-by: Bart Van Assche <bvanassche@acm.org>
    Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
    ---
    block/blk-core.c | 13 +++++++++++++
    block/genhd.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++-
    2 files changed, 62 insertions(+), 1 deletion(-)

    diff --git a/block/blk-core.c b/block/blk-core.c
    index 5847993738f1..e438c3b0815b 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 afdb2c3e5b22..af910e6a0233 100644
    --- a/block/genhd.c
    +++ b/block/genhd.c
    @@ -908,6 +908,20 @@ 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;
    @@ -1539,6 +1553,23 @@ 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);
    @@ -1748,6 +1779,13 @@ 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;
    @@ -1768,6 +1806,13 @@ 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)
    @@ -1775,7 +1820,10 @@ 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().
    */
    --
    2.26.2
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