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[PATCH v1 2/4] block: check virt boundary in bio_will_gap()

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  [PATCH v1 2/4] block: check virt boundary in bio_will_gap() Ming Lei <ming.lei@canonical.com> - 2016-02-19 04:30 +0100
    Re: [PATCH v1 2/4] block: check virt boundary in bio_will_gap() Sagi Grimberg <sagig@dev.mellanox.co.il> - 2016-02-21 19:20 +0100
    Re: [PATCH v1 2/4] block: check virt boundary in bio_will_gap() Christoph Hellwig <hch@infradead.org> - 2016-02-22 10:10 +0100

#1337863 — [PATCH v1 2/4] block: check virt boundary in bio_will_gap()

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.

Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 include/linux/blkdev.h | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4571ef1..5023401 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1372,6 +1372,13 @@ static inline void put_dev_sector(Sector p)
 	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.
@@ -1381,14 +1388,13 @@ static inline bool bvec_gap_to_prev(struct request_queue *q,
 {
 	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],
-- 
1.9.1

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#1338924

Looks fine,

Reviewed-by: Sagi Grimberg <sagig@mellanox.com>

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#1339233

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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