From e19a3ab058fe91c8c54d43dc56dccf7eb386478e Mon Sep 17 00:00:00 2001 From: Kiyoshi Ueda Date: Tue, 11 Dec 2007 17:51:02 -0500 Subject: [PATCH] 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 Signed-off-by: Jun'ichi Nomura Signed-off-by: Jens Axboe --- block/ll_rw_blk.c | 72 ++++++++++++++++++++++++++++++++++++++---- include/linux/blkdev.h | 2 ++ 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 *); /*