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authorKiyoshi Ueda <k-ueda@ct.jp.nec.com>2007-12-11 17:51:02 -0500
committerJens Axboe <jens.axboe@oracle.com>2008-01-28 10:37:04 +0100
commite19a3ab058fe91c8c54d43dc56dccf7eb386478e (patch)
treef62d5af2338484e8a3eec1dc453dec4f949024a7
parentblk_end_request: changing ide normal caller (take 4) (diff)
downloadlinux-dev-e19a3ab058fe91c8c54d43dc56dccf7eb386478e.tar.xz
linux-dev-e19a3ab058fe91c8c54d43dc56dccf7eb386478e.zip
blk_end_request: add callback feature (take 4)
This patch adds a variant of the interface, blk_end_request_callback(), which has driver callback feature. Drivers may need to do special works between end_that_request_first() and end_that_request_last(). For such drivers, blk_end_request_callback() allows it to pass a callback function which is called between end_that_request_first() and end_that_request_last(). This interface is only for fallback of other blk_end_request interfaces. Drivers should avoid their tricky behaviors and use other interfaces as much as possible. Currently, only one driver, ide-cd, needs this interface. So this interface should/will be removed, after the driver removes such tricky behaviors. o ide-cd (cdrom_newpc_intr()) In PIO mode, cdrom_newpc_intr() needs to defer end_that_request_last() until the device clears DRQ_STAT and raises an interrupt after end_that_request_first(). So end_that_request_first() and end_that_request_last() are called separately in cdrom_newpc_intr(). This means blk_end_request_callback() has to return without completing request even if no leftover in the request. To satisfy the requirement, callback function has return value so that drivers can tell blk_end_request_callback() to return without completing request. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r--block/ll_rw_blk.c72
-rw-r--r--include/linux/blkdev.h2
2 files changed, 68 insertions, 6 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index fb951198c70e..919e4baf478b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3825,10 +3825,14 @@ static void complete_request(struct request *rq, int error)
}
/**
- * 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
+ * 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
+ * @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.
@@ -3836,9 +3840,10 @@ static void complete_request(struct request *rq, int error)
*
* Return:
* 0 - we are done with this request
- * 1 - still buffers pending for this request
+ * 1 - this request is not freed yet, it still has pending buffers.
**/
-int blk_end_request(struct request *rq, int error, int nr_bytes)
+static int blk_end_io(struct request *rq, int error, int nr_bytes,
+ int (drv_callback)(struct request *))
{
struct request_queue *q = rq->q;
unsigned long flags = 0UL;
@@ -3855,6 +3860,10 @@ int blk_end_request(struct request *rq, int error, int nr_bytes)
return 1;
}
+ /* Special feature for tricky drivers */
+ if (drv_callback && drv_callback(rq))
+ return 1;
+
add_disk_randomness(rq->rq_disk);
spin_lock_irqsave(q->queue_lock, flags);
@@ -3863,6 +3872,25 @@ int blk_end_request(struct request *rq, int error, int nr_bytes)
return 0;
}
+
+/**
+ * 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)
+{
+ return blk_end_io(rq, error, nr_bytes, NULL);
+}
EXPORT_SYMBOL_GPL(blk_end_request);
/**
@@ -3901,6 +3929,38 @@ int __blk_end_request(struct request *rq, int error, int nr_bytes)
}
EXPORT_SYMBOL_GPL(__blk_end_request);
+/**
+ * blk_end_request_callback - Special helper function for tricky drivers
+ * @rq: the request being processed
+ * @error: 0 for success, < 0 for error
+ * @nr_bytes: number of bytes to complete
+ * @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.
+ * If @rq has leftover, sets it up for the next range of segments.
+ *
+ * This special helper function is used only for existing tricky drivers.
+ * (e.g. cdrom_newpc_intr() of ide-cd)
+ * This interface will be removed when such drivers are rewritten.
+ * Don't use this interface in other places anymore.
+ *
+ * Return:
+ * 0 - we are done with this request
+ * 1 - this request is not freed yet.
+ * this request still has pending buffers or
+ * the driver doesn't want to finish this request yet.
+ **/
+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);
+}
+EXPORT_SYMBOL_GPL(blk_end_request_callback);
+
static void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio)
{
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index aa2341df7932..63fe7542b3fa 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -734,6 +734,8 @@ extern void end_that_request_last(struct request *, int);
extern void end_request(struct request *, int);
extern void end_queued_request(struct request *, int);
extern void end_dequeued_request(struct request *, int);
+extern int blk_end_request_callback(struct request *rq, int error, int nr_bytes,
+ int (drv_callback)(struct request *));
extern void blk_complete_request(struct request *);
/*