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Message-Id: <20071211.174030.10291764.k-ueda@ct.jp.nec.com>
Date: Tue, 11 Dec 2007 17:40:30 -0500 (EST)
From: Kiyoshi Ueda <k-ueda@...jp.nec.com>
To: jens.axboe@...cle.com
Cc: linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
linux-ide@...r.kernel.org, dm-devel@...hat.com,
j-nomura@...jp.nec.com, k-ueda@...jp.nec.com
Subject: [PATCH 01/30] blk_end_request: add new request completion
interface (take 4)
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
blk_end_request takes 'error' as an argument instead of 'uptodate',
which current end_that_request_* take.
The meanings of values are below and the value is used when bio is
completed.
0 : success
< 0 : error
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 interfaces as a part of
generic request completion.
So all device drivers become to call above functions.
To decide whether to call blkdev_dequeue_request(), blk_end_request
uses list_empty(&rq->queuelist) (blk_queued_rq() macro is added for it).
So drivers must re-initialize it using list_init() or so before calling
blk_end_request if drivers use it for its specific purpose.
(Currently, there is no driver which completes request without
re-initializing the queuelist after used it. So rq->queuelist
can be used for the purpose above.)
"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) spin_lock_irqsave()
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> blk_end_request() or spin_lock_irqsave()
__blk_end_request()
spin_unlock_irqrestore()
Signed-off-by: Kiyoshi Ueda <k-ueda@...jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@...jp.nec.com>
---
block/ll_rw_blk.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 4 ++
2 files changed, 100 insertions(+)
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
@@ -3769,6 +3769,102 @@ void end_request(struct request *req, in
}
EXPORT_SYMBOL(end_request);
+static void complete_request(struct request *rq, int error)
+{
+ /*
+ * REMOVEME: This conversion is transitional and will be removed
+ * when old end_that_request_* are unexported.
+ */
+ int uptodate = 1;
+ if (error)
+ uptodate = (error == -EIO) ? 0 : error;
+
+ if (blk_rq_tagged(rq))
+ blk_queue_end_tag(rq->q, rq);
+
+ if (blk_queued_rq(rq))
+ 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
+ * @error: 0 for success, < 0 for 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 error, int nr_bytes)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags = 0UL;
+ /*
+ * REMOVEME: This conversion is transitional and will be removed
+ * when old end_that_request_* are unexported.
+ */
+ int uptodate = 1;
+ if (error)
+ uptodate = (error == -EIO) ? 0 : error;
+
+ 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, error);
+ 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.
+ * @rq: the request being processed
+ * @error: 0 for success, < 0 for error
+ * @nr_bytes: number of bytes to complete
+ *
+ * Description:
+ * Must be called with queue lock held unlike blk_end_request().
+ *
+ * Return:
+ * 0 - we are done with this request
+ * 1 - still buffers pending for this request
+ **/
+int __blk_end_request(struct request *rq, int error, int nr_bytes)
+{
+ /*
+ * REMOVEME: This conversion is transitional and will be removed
+ * when old end_that_request_* are unexported.
+ */
+ int uptodate = 1;
+ if (error)
+ uptodate = (error == -EIO) ? 0 : error;
+
+ 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, error);
+
+ 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-rc4/include/linux/blkdev.h
===================================================================
--- 2.6.24-rc4.orig/include/linux/blkdev.h
+++ 2.6.24-rc4/include/linux/blkdev.h
@@ -539,6 +539,8 @@ enum {
#define blk_fua_rq(rq) ((rq)->cmd_flags & REQ_FUA)
#define blk_bidi_rq(rq) ((rq)->next_rq != NULL)
#define blk_empty_barrier(rq) (blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors)
+/* rq->queuelist of dequeued request must be list_empty() */
+#define blk_queued_rq(rq) (!list_empty(&(rq)->queuelist))
#define list_entry_rq(ptr) list_entry((ptr), struct request, queuelist)
@@ -726,6 +728,8 @@ 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 error, int nr_bytes);
+extern int __blk_end_request(struct request *rq, int error, 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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