[PATCH 1/2] block: handle the null_mapped flag correctly in blk_rq_map_user_iov

From: Christoph Hellwig
Date: Wed Feb 11 2015 - 08:09:26 EST

The tape drivers (and the sg driver in a special case that doesn't matter
here) use the null_mapped flag to tell blk_rq_map_user to not copy around
any data into or out of the bounce buffers. blk_rq_map_user_iov never
got that treatment, which didn't matter until I refactored blk_rq_map_user
to be implemented in terms of blk_rq_map_user_iov.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
block/blk-map.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/block/blk-map.c b/block/blk-map.c
index 0f22911..b8d2725 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -93,6 +93,9 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
if (IS_ERR(bio))
return PTR_ERR(bio);

+ if (map_data && map_data->null_mapped)
+ bio->bi_flags |= (1 << BIO_NULL_MAPPED);
if (bio->bi_iter.bi_size != iter->count) {
* Grab an extra reference to this bio, as bio_unmap_user()

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