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block: add support for limiting gaps in SG lists

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Another restriction inherited for NVMe - those devices don't support
SG lists that have "gaps" in them. Gaps refers to cases where the
previous SG entry doesn't end on a page boundary. For NVMe, all SG
entries must start at offset 0 (except the first) and end on a page
boundary (except the last).

Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2014-06-24 16:22:24 -06:00
commit 66cb45aa41
4 changed files with 28 additions and 0 deletions
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9
include/linux/bio.h
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@ -186,6 +186,15 @@ static inline void *bio_data(struct bio *bio)
#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_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.
*/
static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
{
return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
}
#define bio_io_error(bio) bio_endio((bio), -EIO)
/*