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>
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@@ -259,6 +259,7 @@ struct bio_vec;
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typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *);
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typedef void (prepare_flush_fn) (struct request_queue *, struct request *);
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typedef void (softirq_done_fn)(struct request *);
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typedef int (dma_drain_needed_fn)(struct request *);
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enum blk_queue_state {
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Queue_down,
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@@ -295,6 +296,7 @@ struct request_queue
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merge_bvec_fn *merge_bvec_fn;
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prepare_flush_fn *prepare_flush_fn;
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softirq_done_fn *softirq_done_fn;
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dma_drain_needed_fn *dma_drain_needed;
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/*
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* Dispatch queue sorting
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@@ -699,8 +701,9 @@ extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
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extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
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extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);
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extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
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extern int blk_queue_dma_drain(struct request_queue *q, void *buf,
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unsigned int size);
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extern int blk_queue_dma_drain(struct request_queue *q,
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dma_drain_needed_fn *dma_drain_needed,
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void *buf, unsigned int size);
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extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
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extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
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extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
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