Re: [PATCH 1/2] block: add initial kdoc over the request_queue
From: Damien Le Moal <hidden>
Date: 2020-06-24 00:34:02
Also in:
lkml
On 2020/06/24 7:03, Luis Chamberlain wrote:
quoted hunk ↗ jump to hunk
We start off with an initial description of the request_queue data structure, followed by describing the purpose of the debugfs_mutex debugfs_dir, and blk_trace. Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- include/linux/blkdev.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 70461b347169..ea319c2b0593 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h@@ -394,6 +394,26 @@ static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev, #endif /* CONFIG_BLK_DEV_ZONED */ +/** + * struct request_queue - block device driver request queue + * @debugfs_mutex: used to protect access to the @debugfs_dir + * @blk_trace: used by blktrace to keep track of setup / tracing + * @debugfs_dir: directory created to place debugfs information. This is always + * created for make_request and request-based block drivers upon + * initialization. blktrace requires for this directory to be created,
s/requires for/requires/ (may be, not sure of my English grammar on this one :))
+ * and so it will be created on demand if its block driver type does not + * create it opon initialization.
s/opon/upon/
+ * + * The request_queue is used to manage incoming block layer device driver + * requests. We have three main type of block driver types which end up making
We have three main types of block drivers which...
+ * use of the request_queue: + * + * o make_request block drivers (multiqueue) + * o request-based block drivers
Isn't this second one BIO based drivers, like device-mapper BIO targets ?
+ * o custom solutions such as scsi-generic
The SG driver does not create a request queue, it uses the one of the scsi device created by the scsi stack. Is this what you mean here ? Saying scsi-generic kind of implies sg driver.
+ *
+ * All partitions share the same request_queue data structure.
+ */
struct request_queue {
struct request *last_merge;
struct elevator_queue *elevator;-- Damien Le Moal Western Digital Research