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Subject[PATCH 01/28] blk_end_request: add new request completion interface (take 3)
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This patch adds 2 new interfaces for request completion:
o blk_end_request() : called without queue lock
o __blk_end_request() : called with queue lock held

Some device drivers call some generic functions below between
end_that_request_{first/chunk} and end_that_request_last().
o add_disk_randomness()
o blk_queue_end_tag()
o blkdev_dequeue_request()
These are called in the blk_end_request() as a part of generic
request completion.
So all device drivers become to call above functions.
"Normal" drivers can be converted to use blk_end_request()
in a standard way shown below.

a) end_that_request_{chunk/first}
spin_lock_irqsave()
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> blk_end_request()
b) spin_lock_irqsave()
end_that_request_{chunk/first}
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> spin_lock_irqsave()
__blk_end_request()
spin_unlock_irqsave()
c) end_that_request_last()
=> __blk_end_request()

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 | 67 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 2 +
2 files changed, 69 insertions(+)
Index: 2.6.24-rc3-mm2/block/ll_rw_blk.c
===================================================================
--- 2.6.24-rc3-mm2.orig/block/ll_rw_blk.c
+++ 2.6.24-rc3-mm2/block/ll_rw_blk.c
@@ -3769,6 +3769,73 @@ void end_request(struct request *req, in
}
EXPORT_SYMBOL(end_request);

+static void complete_request(struct request *rq, int uptodate)
+{
+ if (blk_rq_tagged(rq))
+ blk_queue_end_tag(rq->q, rq);
+
+ /* rq->queuelist of dequeued request should be list_empty() */
+ if (!list_empty(&rq->queuelist))
+ blkdev_dequeue_request(rq);
+
+ end_that_request_last(rq, uptodate);
+}
+
+/**
+ * blk_end_request - Helper function for drivers to complete the request.
+ * @rq: the request being processed
+ * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
+ * @nr_bytes: number of bytes to complete
+ *
+ * Description:
+ * Ends I/O on a number of bytes attached to @rq.
+ * If @rq has leftover, sets it up for the next range of segments.
+ *
+ * Return:
+ * 0 - we are done with this request
+ * 1 - still buffers pending for this request
+ **/
+int blk_end_request(struct request *rq, int uptodate, int nr_bytes)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags = 0UL;
+
+ if (blk_fs_request(rq) || blk_pc_request(rq)) {
+ if (__end_that_request_first(rq, uptodate, nr_bytes))
+ return 1;
+ }
+
+ add_disk_randomness(rq->rq_disk);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ complete_request(rq, uptodate);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(blk_end_request);
+
+/**
+ * __blk_end_request - Helper function for drivers to complete the request.
+ *
+ * Description:
+ * Must be called with queue lock held unlike blk_end_request().
+ **/
+int __blk_end_request(struct request *rq, int uptodate, int nr_bytes)
+{
+ if (blk_fs_request(rq) || blk_pc_request(rq)) {
+ if (__end_that_request_first(rq, uptodate, nr_bytes))
+ return 1;
+ }
+
+ add_disk_randomness(rq->rq_disk);
+
+ complete_request(rq, uptodate);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__blk_end_request);
+
static void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio)
{
Index: 2.6.24-rc3-mm2/include/linux/blkdev.h
===================================================================
--- 2.6.24-rc3-mm2.orig/include/linux/blkdev.h
+++ 2.6.24-rc3-mm2/include/linux/blkdev.h
@@ -725,6 +725,8 @@ static inline void blk_run_address_space
* for parts of the original function. This prevents
* code duplication in drivers.
*/
+extern int blk_end_request(struct request *rq, int uptodate, int nr_bytes);
+extern int __blk_end_request(struct request *rq, int uptodate, int nr_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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