[PATCH V5 08/33] block: introduce segment_last_page()
From: Ming Lei <hidden>
Date: 2018-05-24 09:01:13
Subsystem:
the rest · Maintainer:
Linus Torvalds
BTRFS and guard_bio_eod() need to get the last page from one segment, so introduce this helper to make them happy. Signed-off-by: Ming Lei <redacted> --- include/linux/bvec.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 84c395feed49..217afcd83a15 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h@@ -219,4 +219,26 @@ static inline bool bvec_iter_seg_advance(const struct bio_vec *bv, .bi_bvec_done = 0, \ } +/* get the last page from the multipage bvec and store it in @pg */ +static inline void segment_last_page(const struct bio_vec *seg, + struct bio_vec *pg) +{ + unsigned total = seg->bv_offset + seg->bv_len; + unsigned last_page = total / PAGE_SIZE; + + if (last_page * PAGE_SIZE == total) + last_page--; + + pg->bv_page = nth_page(seg->bv_page, last_page); + + /* the whole segment is inside the last page */ + if (seg->bv_offset >= last_page * PAGE_SIZE) { + pg->bv_offset = seg->bv_offset % PAGE_SIZE; + pg->bv_len = seg->bv_len; + } else { + pg->bv_offset = 0; + pg->bv_len = total - last_page * PAGE_SIZE; + } +} + #endif /* __LINUX_BVEC_ITER_H */
--
2.9.5