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-   -   blk_end_request: add bidi completion interface (take 4) (http://www.linux-archive.org/device-mapper-development/17553-blk_end_request-add-bidi-completion-interface-take-4-a.html)

Kiyoshi Ueda 12-11-2007 09:51 PM

blk_end_request: add bidi completion interface (take 4)
 
This patch adds a variant of the interface, blk_end_bidi_request(),
which completes a bidi request.

Bidi request must be completed as a whole, both rq and rq->next_rq
at once. So the interface has 2 arguments for completion size.

As for ->end_io, only rq->end_io is called (rq->next_rq->end_io is not
called). So if special completion handling is needed, the handler
must be set to rq->end_io.
And the handler must take care of freeing next_rq too, since
the interface doesn't care of it if rq->end_io is not NULL.

Cc: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
---
block/ll_rw_blk.c | 40 +++++++++++++++++++++++++++++++++++-----
include/linux/blkdev.h | 2 ++
2 files changed, 37 insertions(+), 5 deletions(-)

Index: 2.6.24-rc4/block/ll_rw_blk.c
================================================== =================
--- 2.6.24-rc4.orig/block/ll_rw_blk.c
+++ 2.6.24-rc4/block/ll_rw_blk.c
@@ -3799,6 +3799,9 @@ static void complete_request(struct requ
if (blk_queued_rq(rq))
blkdev_dequeue_request(rq);

+ if (blk_bidi_rq(rq) && !rq->end_io)
+ __blk_put_request(rq->next_rq->q, rq->next_rq);
+
end_that_request_last(rq, uptodate);
}

@@ -3806,14 +3809,15 @@ static void complete_request(struct requ
* blk_end_io - Generic end_io function to complete a request.
* @rq: the request being processed
* @error: 0 for success, < 0 for error
- * @nr_bytes: number of bytes to complete
+ * @nr_bytes: number of bytes to complete @rq
+ * @bidi_bytes: number of bytes to complete @rq->next_rq
* @drv_callback: function called between completion of bios in the request
* and completion of the request.
* If the callback returns non 0, this helper returns without
* completion of the request.
*
* Description:
- * Ends I/O on a number of bytes attached to @rq.
+ * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
* If @rq has leftover, sets it up for the next range of segments.
*
* Return:
@@ -3821,7 +3825,7 @@ static void complete_request(struct requ
* 1 - this request is not freed yet, it still has pending buffers.
**/
static int blk_end_io(struct request *rq, int error, int nr_bytes,
- int (drv_callback)(struct request *))
+ int bidi_bytes, int (drv_callback)(struct request *))
{
struct request_queue *q = rq->q;
unsigned long flags = 0UL;
@@ -3836,6 +3840,11 @@ static int blk_end_io(struct request *rq
if (blk_fs_request(rq) || blk_pc_request(rq)) {
if (__end_that_request_first(rq, uptodate, nr_bytes))
return 1;
+
+ /* Bidi request must be completed as a whole */
+ if (blk_bidi_rq(rq) &&
+ __end_that_request_first(rq->next_rq, uptodate, bidi_bytes))
+ return 1;
}

/* Special feature for tricky drivers */
@@ -3867,7 +3876,7 @@ static int blk_end_io(struct request *rq
**/
int blk_end_request(struct request *rq, int error, int nr_bytes)
{
- return blk_end_io(rq, error, nr_bytes, NULL);
+ return blk_end_io(rq, error, nr_bytes, 0, NULL);
}
EXPORT_SYMBOL_GPL(blk_end_request);

@@ -3908,6 +3917,27 @@ int __blk_end_request(struct request *rq
EXPORT_SYMBOL_GPL(__blk_end_request);

/**
+ * blk_end_bidi_request - Helper function for drivers to complete bidi request.
+ * @rq: the bidi request being processed
+ * @error: 0 for success, < 0 for error
+ * @nr_bytes: number of bytes to complete @rq
+ * @bidi_bytes: number of bytes to complete @rq->next_rq
+ *
+ * Description:
+ * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
+ *
+ * Return:
+ * 0 - we are done with this request
+ * 1 - still buffers pending for this request
+ **/
+int blk_end_bidi_request(struct request *rq, int error, int nr_bytes,
+ int bidi_bytes)
+{
+ return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
+}
+EXPORT_SYMBOL_GPL(blk_end_bidi_request);
+
+/**
* blk_end_request_callback - Special helper function for tricky drivers
* @rq: the request being processed
* @error: 0 for success, < 0 for error
@@ -3935,7 +3965,7 @@ EXPORT_SYMBOL_GPL(__blk_end_request);
int blk_end_request_callback(struct request *rq, int error, int nr_bytes,
int (drv_callback)(struct request *))
{
- return blk_end_io(rq, error, nr_bytes, drv_callback);
+ return blk_end_io(rq, error, nr_bytes, 0, drv_callback);
}
EXPORT_SYMBOL_GPL(blk_end_request_callback);

Index: 2.6.24-rc4/include/linux/blkdev.h
================================================== =================
--- 2.6.24-rc4.orig/include/linux/blkdev.h
+++ 2.6.24-rc4/include/linux/blkdev.h
@@ -730,6 +730,8 @@ static inline void blk_run_address_space
*/
extern int blk_end_request(struct request *rq, int error, int nr_bytes);
extern int __blk_end_request(struct request *rq, int error, int nr_bytes);
+extern int blk_end_bidi_request(struct request *rq, int error, int nr_bytes,
+ int bidi_bytes);
extern int end_that_request_first(struct request *, int, int);
extern int end_that_request_chunk(struct request *, int, int);
extern void end_that_request_last(struct request *, int);

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