From 66cb45aa41315d1d9972cada354fbdf7870d7714 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 24 Jun 2014 16:22:24 -0600 Subject: block: add support for limiting gaps in SG lists 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 --- include/linux/bio.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/bio.h') diff --git a/include/linux/bio.h b/include/linux/bio.h index f91decbca96b..d2633ee099d9 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -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) /* -- cgit v1.2.3