@@ -219,4 +219,29 @@ 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 */
BTRFS and guard_bio_eod() need to get the last singlepage segment from one multipage bvec, so introduce this helper to make them happy. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- include/linux/bvec.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)