From cc97923a5bccc776851c242b61015faf288d5c22 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 14 Apr 2020 09:42:24 +0200
Subject: block: move dma drain handling to scsi
Don't burden the common block code with with specifics of the libata DMA
draining mechanism. Instead move most of the code to the scsi midlayer.
That also means the nr_phys_segments adjustments in the blk-mq fast path
can go away entirely, given that SCSI never looks at nr_phys_segments
after mapping the request to a scatterlist.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-merge.c | 14 --------------
1 file changed, 14 deletions(-)
(limited to 'block/blk-merge.c')
diff --git a/block/blk-merge.c b/block/blk-merge.c
index ee618cdb141e..25f5a5e00ee6 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -539,20 +539,6 @@ int __blk_rq_map_sg(struct request_queue *q, struct request *rq,
rq->extra_len += pad_len;
}
- if (q->dma_drain_size && q->dma_drain_needed(rq)) {
- if (op_is_write(req_op(rq)))
- memset(q->dma_drain_buffer, 0, q->dma_drain_size);
-
- sg_unmark_end(*last_sg);
- *last_sg = sg_next(*last_sg);
- sg_set_page(*last_sg, virt_to_page(q->dma_drain_buffer),
- q->dma_drain_size,
- ((unsigned long)q->dma_drain_buffer) &
- (PAGE_SIZE - 1));
- nsegs++;
- rq->extra_len += q->dma_drain_size;
- }
-
if (*last_sg)
sg_mark_end(*last_sg);
--
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