[PATCH 4.4 69/74] block: check virt boundary in bio_will_gap()

Greg Kroah-Hartman
2016-03-08T00:05:18Z

From: Ming Lei <ming.lei@canonical.com>

commit e0af29171aa8912e1ca95023b75ef336cd70d661 upstream.

In the following patch, the way for figuring out
the last bvec will be changed with a bit cost introduced,
so return immediately if the queue doesn't have virt
boundary limit. Actually most of devices have not
this limit.

Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/blkdev.h | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1367,6 +1367,13 @@ static inline void put_dev_sector(Sector
page_cache_release(p.v);
}

+static inline bool __bvec_gap_to_prev(struct request_queue *q,
+ struct bio_vec *bprv, unsigned int offset)
+{
+ return offset ||
+ ((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
+}
+
/*
* Check if adding a bio_vec after bprv with offset would create a gap in
* the SG list. Most drivers don't care about this, but some do.
@@ -1376,18 +1383,17 @@ static inline bool bvec_gap_to_prev(stru
{
if (!queue_virt_boundary(q))
return false;
- return offset ||
- ((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
+ return __bvec_gap_to_prev(q, bprv, offset);
}

static inline bool bio_will_gap(struct request_queue *q, struct bio *prev,
struct bio *next)
{
- if (!bio_has_data(prev))
+ if (!bio_has_data(prev) || !queue_virt_boundary(q))
return false;

- return bvec_gap_to_prev(q, &prev->bi_io_vec[prev->bi_vcnt - 1],
- next->bi_io_vec[0].bv_offset);
+ return __bvec_gap_to_prev(q, &prev->bi_io_vec[prev->bi_vcnt - 1],
+ next->bi_io_vec[0].bv_offset);
}

static inline bool req_gap_back_merge(struct request *req, struct bio *bio)