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From: Bart Van Assche <>
To: Jens Axboe <>
Cc:, Christoph Hellwig <>,
	Bart Van Assche <>,
	Ming Lei <>, Hannes Reinecke <>
Subject: [PATCH] block: Update blk_update_request() documentation
Date: Wed, 19 May 2021 10:52:26 -0700	[thread overview]
Message-ID: <> (raw)

Although the original intent was to use blk_update_request() in stacking
block drivers only, it is used much more widely today. Reflect this in the
documentation block above this function. See also:
* commit 32fab448e5e8 ("block: add request update interface").
* commit 2e60e02297cf ("block: clean up request completion API").
* commit ed6565e73424 ("block: handle partial completions for special
  payload requests").

Cc: Christoph Hellwig <>
Cc: Ming Lei <>
Cc: Hannes Reinecke <>
Signed-off-by: Bart Van Assche <>
 block/blk-core.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 689aac2625d2..b65da5a33e20 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1385,26 +1385,22 @@ void blk_steal_bios(struct bio_list *list, struct request *rq)
- * blk_update_request - Special helper function for request stacking drivers
+ * blk_update_request - Complete multiple bytes without completing the request
  * @req:      the request being processed
  * @error:    block status code
- * @nr_bytes: number of bytes to complete @req
+ * @nr_bytes: number of bytes to complete for @req
  * Description:
  *     Ends I/O on a number of bytes attached to @req, but doesn't complete
  *     the request structure even if @req doesn't have leftover.
  *     If @req has leftover, sets it up for the next range of segments.
- *     This special helper function is only for request stacking drivers
- *     (e.g. request-based dm) so that they can handle partial completion.
- *     Actual device drivers should use blk_mq_end_request instead.
- *
  *     Passing the result of blk_rq_bytes() as @nr_bytes guarantees
  *     %false return from this function.
  * Note:
- *	The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
- *	blk_rq_bytes() and in blk_update_request().
+ *	The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in this function
+ *      except in the consistency check at the end of this function.
  * Return:
  *     %false - this request doesn't have any more data

             reply	other threads:[~2021-05-19 17:52 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 17:52 Bart Van Assche [this message]
2021-06-03 20:03 ` [PATCH] block: Update blk_update_request() documentation Bart Van Assche
2021-06-03 20:37 ` Jens Axboe

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