BTRFS and guard_bio_eod() need to get the last singlepage segment from one multipage bvec, so introduce this helper to make them happy.
Cc: Dave Chinner <[email protected]> Cc: Kent Overstreet <[email protected]> Cc: Mike Snitzer <[email protected]> Cc: [email protected] Cc: Alexander Viro <[email protected]> Cc: [email protected] Cc: Shaohua Li <[email protected]> Cc: [email protected] Cc: [email protected] Cc: David Sterba <[email protected]> Cc: [email protected] Cc: Darrick J. Wong <[email protected]> Cc: [email protected] Cc: Gao Xiang <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Theodore Ts'o <[email protected]> Cc: [email protected] Cc: Coly Li <[email protected]> Cc: [email protected] Cc: Boaz Harrosh <[email protected]> Cc: Bob Peterson <[email protected]> Cc: [email protected] Signed-off-by: Ming Lei <[email protected]> --- include/linux/bvec.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 3d61352cd8cf..01616a0b6220 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -216,4 +216,29 @@ static inline bool mp_bvec_iter_advance(const struct bio_vec *bv, .bi_bvec_done = 0, \ } +/* + * Get the last singlepage segment from the multipage bvec and store it + * in @seg + */ +static inline void bvec_last_segment(const struct bio_vec *bvec, + struct bio_vec *seg) +{ + unsigned total = bvec->bv_offset + bvec->bv_len; + unsigned last_page = total / PAGE_SIZE; + + if (last_page * PAGE_SIZE == total) + last_page--; + + seg->bv_page = nth_page(bvec->bv_page, last_page); + + /* the whole segment is inside the last page */ + if (bvec->bv_offset >= last_page * PAGE_SIZE) { + seg->bv_offset = bvec->bv_offset % PAGE_SIZE; + seg->bv_len = bvec->bv_len; + } else { + seg->bv_offset = 0; + seg->bv_len = total - last_page * PAGE_SIZE; + } +} + #endif /* __LINUX_BVEC_ITER_H */ -- 2.9.5
