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| author | Tejun Heo <htejun@gmail.com> | 2008-02-19 11:36:53 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-02-19 11:36:53 +0100 |
| commit | 2fb98e8414c42cb14698833aac640b143b9ade4f (patch) | |
| tree | ab241305b5ce3ea5ef3e76df7abe04b831cd9e34 | |
| parent | 6b00769fe1502b4ad97bb327ef7ac971b208bfb5 (diff) | |
| download | lwn-2fb98e8414c42cb14698833aac640b143b9ade4f.tar.gz lwn-2fb98e8414c42cb14698833aac640b143b9ade4f.zip | |
block: implement request_queue->dma_drain_needed
Draining shouldn't be done for commands where overflow may indicate
data integrity issues. Add dma_drain_needed callback to
request_queue. Drain buffer is appened iff this function returns
non-zero.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | block/blk-merge.c | 2 | ||||
| -rw-r--r-- | block/blk-settings.c | 7 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 7 |
3 files changed, 11 insertions, 5 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 39f2e077a014..bef1b4d0fc02 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -220,7 +220,7 @@ new_segment: bvprv = bvec; } /* segments in rq */ - if (q->dma_drain_size) { + if (q->dma_drain_size && q->dma_drain_needed(rq)) { sg->page_link &= ~0x02; sg = sg_next(sg); sg_set_page(sg, virt_to_page(q->dma_drain_buffer), diff --git a/block/blk-settings.c b/block/blk-settings.c index 13536a388d27..9a8ffdd0ce3d 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -296,6 +296,7 @@ EXPORT_SYMBOL(blk_queue_stack_limits); * blk_queue_dma_drain - Set up a drain buffer for excess dma. * * @q: the request queue for the device + * @dma_drain_needed: fn which returns non-zero if drain is necessary * @buf: physically contiguous buffer * @size: size of the buffer in bytes * @@ -315,14 +316,16 @@ EXPORT_SYMBOL(blk_queue_stack_limits); * device can support otherwise there won't be room for the drain * buffer. */ -int blk_queue_dma_drain(struct request_queue *q, void *buf, - unsigned int size) +extern int blk_queue_dma_drain(struct request_queue *q, + dma_drain_needed_fn *dma_drain_needed, + void *buf, unsigned int size) { if (q->max_hw_segments < 2 || q->max_phys_segments < 2) return -EINVAL; /* make room for appending the drain */ --q->max_hw_segments; --q->max_phys_segments; + q->dma_drain_needed = dma_drain_needed; q->dma_drain_buffer = buf; q->dma_drain_size = size; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index f1fe9fbf1c0e..6fe67d1939c2 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -259,6 +259,7 @@ struct bio_vec; typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *); typedef void (prepare_flush_fn) (struct request_queue *, struct request *); typedef void (softirq_done_fn)(struct request *); +typedef int (dma_drain_needed_fn)(struct request *); enum blk_queue_state { Queue_down, @@ -295,6 +296,7 @@ struct request_queue merge_bvec_fn *merge_bvec_fn; prepare_flush_fn *prepare_flush_fn; softirq_done_fn *softirq_done_fn; + dma_drain_needed_fn *dma_drain_needed; /* * Dispatch queue sorting @@ -699,8 +701,9 @@ extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short); extern void blk_queue_max_segment_size(struct request_queue *, unsigned int); extern void blk_queue_hardsect_size(struct request_queue *, unsigned short); extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b); -extern int blk_queue_dma_drain(struct request_queue *q, void *buf, - unsigned int size); +extern int blk_queue_dma_drain(struct request_queue *q, + dma_drain_needed_fn *dma_drain_needed, + void *buf, unsigned int size); extern void blk_queue_segment_boundary(struct request_queue *, unsigned long); extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn); extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *); |