diff mbox series

[05/26] block: add blk_alloc_disk and blk_cleanup_disk APIs

Message ID 20210521055116.1053587-6-hch@lst.de (mailing list archive)
State New
Headers show
Series [01/26] block: refactor device number setup in __device_add_disk | expand

Commit Message

Christoph Hellwig May 21, 2021, 5:50 a.m. UTC
Add two new APIs to allocate and free a gendisk including the
request_queue for use with BIO based drivers.  This is to avoid
boilerplate code in drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c         | 35 +++++++++++++++++++++++++++++++++++
 include/linux/genhd.h | 22 ++++++++++++++++++++++
 2 files changed, 57 insertions(+)

Comments

Luis Chamberlain May 21, 2021, 5:44 p.m. UTC | #1
On Fri, May 21, 2021 at 07:50:55AM +0200, Christoph Hellwig wrote:
> Add two new APIs to allocate and free a gendisk including the
> request_queue for use with BIO based drivers.  This is to avoid
> boilerplate code in drivers.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/genhd.c         | 35 +++++++++++++++++++++++++++++++++++
>  include/linux/genhd.h | 22 ++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/block/genhd.c b/block/genhd.c
> index e4974af3d729..6d4ce962866d 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -1302,6 +1302,25 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
>  }
>  EXPORT_SYMBOL(__alloc_disk_node);
>  
> +struct gendisk *__blk_alloc_disk(int node)
> +{
> +	struct request_queue *q;
> +	struct gendisk *disk;
> +
> +	q = blk_alloc_queue(node);
> +	if (!q)
> +		return NULL;
> +
> +	disk = __alloc_disk_node(0, node);
> +	if (!disk) {
> +		blk_cleanup_queue(q);
> +		return NULL;
> +	}
> +	disk->queue = q;
> +	return disk;
> +}
> +EXPORT_SYMBOL(__blk_alloc_disk);

Its not obvious to me why using this new API requires you then to
set minors explicitly to 1, and yet here underneath we see the minors
argument passed is 0.

Nor is it clear from the documentation.

  Luis
Hannes Reinecke May 23, 2021, 7:55 a.m. UTC | #2
On 5/21/21 7:50 AM, Christoph Hellwig wrote:
> Add two new APIs to allocate and free a gendisk including the
> request_queue for use with BIO based drivers.  This is to avoid
> boilerplate code in drivers.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   block/genhd.c         | 35 +++++++++++++++++++++++++++++++++++
>   include/linux/genhd.h | 22 ++++++++++++++++++++++
>   2 files changed, 57 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
Christoph Hellwig May 24, 2021, 7:24 a.m. UTC | #3
On Fri, May 21, 2021 at 05:44:07PM +0000, Luis Chamberlain wrote:
> Its not obvious to me why using this new API requires you then to
> set minors explicitly to 1, and yet here underneath we see the minors
> argument passed is 0.
> 
> Nor is it clear from the documentation.

Basically for all new drivers no one should set minors at all, and the
dynamic dev_t mechanism does all the work.  For converted old drivers
minors is set manually instead of being passed an an argument that
should be 0 for all new drivers.
diff mbox series

Patch

diff --git a/block/genhd.c b/block/genhd.c
index e4974af3d729..6d4ce962866d 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1302,6 +1302,25 @@  struct gendisk *__alloc_disk_node(int minors, int node_id)
 }
 EXPORT_SYMBOL(__alloc_disk_node);
 
+struct gendisk *__blk_alloc_disk(int node)
+{
+	struct request_queue *q;
+	struct gendisk *disk;
+
+	q = blk_alloc_queue(node);
+	if (!q)
+		return NULL;
+
+	disk = __alloc_disk_node(0, node);
+	if (!disk) {
+		blk_cleanup_queue(q);
+		return NULL;
+	}
+	disk->queue = q;
+	return disk;
+}
+EXPORT_SYMBOL(__blk_alloc_disk);
+
 /**
  * put_disk - decrements the gendisk refcount
  * @disk: the struct gendisk to decrement the refcount for
@@ -1319,6 +1338,22 @@  void put_disk(struct gendisk *disk)
 }
 EXPORT_SYMBOL(put_disk);
 
+/**
+ * blk_cleanup_disk - shutdown a gendisk allocated by blk_alloc_disk
+ * @disk: gendisk to shutdown
+ *
+ * Mark the queue hanging off @disk DYING, drain all pending requests, then mark
+ * the queue DEAD, destroy and put it and the gendisk structure.
+ *
+ * Context: can sleep
+ */
+void blk_cleanup_disk(struct gendisk *disk)
+{
+	blk_cleanup_queue(disk->queue);
+	put_disk(disk);
+}
+EXPORT_SYMBOL(blk_cleanup_disk);
+
 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
 {
 	char event[] = "DISK_RO=1";
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index a5443f0b139d..03aa12730634 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -278,6 +278,28 @@  extern void put_disk(struct gendisk *disk);
 
 #define alloc_disk(minors) alloc_disk_node(minors, NUMA_NO_NODE)
 
+/**
+ * blk_alloc_disk - allocate a gendisk structure
+ * @node_id: numa node to allocate on
+ *
+ * Allocate and pre-initialize a gendisk structure for use with BIO based
+ * drivers.
+ *
+ * Context: can sleep
+ */
+#define blk_alloc_disk(node_id)						\
+({									\
+	struct gendisk *__disk = __blk_alloc_disk(node_id);		\
+	static struct lock_class_key __key;				\
+									\
+	if (__disk)							\
+		lockdep_init_map(&__disk->lockdep_map,			\
+			"(bio completion)", &__key, 0);			\
+	__disk;								\
+})
+struct gendisk *__blk_alloc_disk(int node);
+void blk_cleanup_disk(struct gendisk *disk);
+
 int __register_blkdev(unsigned int major, const char *name,
 		void (*probe)(dev_t devt));
 #define register_blkdev(major, name) \