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authorTejun Heo <htejun@gmail.com>2008-02-19 05:36:53 -0500
committerJens Axboe <jens.axboe@oracle.com>2008-02-19 05:36:53 -0500
commit2fb98e8414c42cb14698833aac640b143b9ade4f (patch)
treeab241305b5ce3ea5ef3e76df7abe04b831cd9e34 /block
parent6b00769fe1502b4ad97bb327ef7ac971b208bfb5 (diff)
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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-merge.c2
-rw-r--r--block/blk-settings.c7
2 files changed, 6 insertions, 3 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:
220 bvprv = bvec; 220 bvprv = bvec;
221 } /* segments in rq */ 221 } /* segments in rq */
222 222
223 if (q->dma_drain_size) { 223 if (q->dma_drain_size && q->dma_drain_needed(rq)) {
224 sg->page_link &= ~0x02; 224 sg->page_link &= ~0x02;
225 sg = sg_next(sg); 225 sg = sg_next(sg);
226 sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 226 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);
296 * blk_queue_dma_drain - Set up a drain buffer for excess dma. 296 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
297 * 297 *
298 * @q: the request queue for the device 298 * @q: the request queue for the device
299 * @dma_drain_needed: fn which returns non-zero if drain is necessary
299 * @buf: physically contiguous buffer 300 * @buf: physically contiguous buffer
300 * @size: size of the buffer in bytes 301 * @size: size of the buffer in bytes
301 * 302 *
@@ -315,14 +316,16 @@ EXPORT_SYMBOL(blk_queue_stack_limits);
315 * device can support otherwise there won't be room for the drain 316 * device can support otherwise there won't be room for the drain
316 * buffer. 317 * buffer.
317 */ 318 */
318int blk_queue_dma_drain(struct request_queue *q, void *buf, 319extern int blk_queue_dma_drain(struct request_queue *q,
319 unsigned int size) 320 dma_drain_needed_fn *dma_drain_needed,
321 void *buf, unsigned int size)
320{ 322{
321 if (q->max_hw_segments < 2 || q->max_phys_segments < 2) 323 if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
322 return -EINVAL; 324 return -EINVAL;
323 /* make room for appending the drain */ 325 /* make room for appending the drain */
324 --q->max_hw_segments; 326 --q->max_hw_segments;
325 --q->max_phys_segments; 327 --q->max_phys_segments;
328 q->dma_drain_needed = dma_drain_needed;
326 q->dma_drain_buffer = buf; 329 q->dma_drain_buffer = buf;
327 q->dma_drain_size = size; 330 q->dma_drain_size = size;
328 331