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 <dchin...@redhat.com>
Cc: Kent Overstreet <kent.overstr...@gmail.com>
Cc: Mike Snitzer <snit...@redhat.com>
Cc: dm-de...@redhat.com
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: linux-fsde...@vger.kernel.org
Cc: Shaohua Li <s...@kernel.org>
Cc: linux-r...@vger.kernel.org
Cc: linux-er...@lists.ozlabs.org
Cc: David Sterba <dste...@suse.com>
Cc: linux-bt...@vger.kernel.org
Cc: Darrick J. Wong <darrick.w...@oracle.com>
Cc: linux-...@vger.kernel.org
Cc: Gao Xiang <gaoxian...@huawei.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Theodore Ts'o <ty...@mit.edu>
Cc: linux-e...@vger.kernel.org
Cc: Coly Li <col...@suse.de>
Cc: linux-bca...@vger.kernel.org
Cc: Boaz Harrosh <o...@electrozaur.com>
Cc: Bob Peterson <rpete...@redhat.com>
Cc: cluster-devel@redhat.com
Signed-off-by: Ming Lei <ming....@redhat.com>
---
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
