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block: check virt boundary in bio_will_gap()

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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>
This commit is contained in:
Ming Lei 2016-02-26 23:40:51 +08:00 committed by Jens Axboe
parent 7bcd79ac50
commit e0af29171a
1 changed files with 11 additions and 5 deletions
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16
include/linux/blkdev.h
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@ -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.
@ -1381,18 +1388,17 @@ 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],
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)