[PATCH v2 22/51] block: introduce bio_for_each_segment_mp()

Ming Lei
2017-06-26T12:10:05Z

This helper is used to iterate multipage bvec and it is
required in bio_clone().

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/bio.h | 39 ++++++++++++++++++++++++++++++++++-----
include/linux/bvec.h | 37 ++++++++++++++++++++++++++++++++-----
2 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index d425be4d1ced..bdbc9480229d 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -68,6 +68,9 @@
#define bio_data_dir(bio) \
(op_is_write(bio_op(bio)) ? WRITE : READ)

+#define bio_iter_iovec_mp(bio, iter) \
+ bvec_iter_bvec_mp((bio)->bi_io_vec, (iter))
+
/*
* Check whether this bio carries any data or not. A NULL bio is allowed.
*/
@@ -163,15 +166,31 @@ static inline void *bio_data(struct bio *bio)
#define bio_for_each_segment_all(bvl, bio, i) \
for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)

-static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
- unsigned bytes)
+static inline void __bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
+ unsigned bytes, bool mp)
{
iter->bi_sector += bytes >> 9;

- if (bio_no_advance_iter(bio))
+ if (bio_no_advance_iter(bio)) {
iter->bi_size -= bytes;
- else
- bvec_iter_advance(bio->bi_io_vec, iter, bytes);
+ } else {
+ if (!mp)
+ bvec_iter_advance(bio->bi_io_vec, iter, bytes);
+ else
+ bvec_iter_advance_mp(bio->bi_io_vec, iter, bytes);
+ }
+}
+
+static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
+ unsigned bytes)
+{
+ __bio_advance_iter(bio, iter, bytes, false);
+}
+
+static inline void bio_advance_iter_mp(struct bio *bio, struct bvec_iter *iter,
+ unsigned bytes)
+{
+ __bio_advance_iter(bio, iter, bytes, true);
}

#define __bio_for_each_segment(bvl, bio, iter, start) \
@@ -187,6 +206,16 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
#define bio_for_each_segment(bvl, bio, iter) \
__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)

+#define __bio_for_each_segment_mp(bvl, bio, iter, start) \
+ for (iter = (start); \
+ (iter).bi_size && \
+ ((bvl = bio_iter_iovec_mp((bio), (iter))), 1); \
+ bio_advance_iter_mp((bio), &(iter), (bvl).bv_len))
+
+/* returns one real segment(multipage bvec) each time */
+#define bio_for_each_segment_mp(bvl, bio, iter) \
+ __bio_for_each_segment_mp(bvl, bio, iter, (bio)->bi_iter)
+
#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)

static inline unsigned bio_segments(struct bio *bio)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 61632e9db3b8..5c51c58fe202 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -128,16 +128,29 @@ struct bvec_iter {
.bv_offset = bvec_iter_offset((bvec), (iter)), \
})

-static inline void bvec_iter_advance(const struct bio_vec *bv,
- struct bvec_iter *iter,
- unsigned bytes)
+#define bvec_iter_bvec_mp(bvec, iter) \
+((struct bio_vec) { \
+ .bv_page = bvec_iter_page_mp((bvec), (iter)), \
+ .bv_len = bvec_iter_len_mp((bvec), (iter)), \
+ .bv_offset = bvec_iter_offset_mp((bvec), (iter)), \
+})
+
+static inline void __bvec_iter_advance(const struct bio_vec *bv,
+ struct bvec_iter *iter,
+ unsigned bytes, bool mp)
{
WARN_ONCE(bytes > iter->bi_size,
"Attempted to advance past end of bvec iter\n");

while (bytes) {
- unsigned iter_len = bvec_iter_len(bv, *iter);
- unsigned len = min(bytes, iter_len);
+ unsigned len;
+
+ if (mp)
+ len = bvec_iter_len_mp(bv, *iter);
+ else
+ len = bvec_iter_len_sp(bv, *iter);
+
+ len = min(bytes, len);

bytes -= len;
iter->bi_size -= len;
@@ -150,6 +163,20 @@ static inline void bvec_iter_advance(const struct bio_vec *bv,
}
}

+static inline void bvec_iter_advance(const struct bio_vec *bv,
+ struct bvec_iter *iter,
+ unsigned bytes)
+{
+ __bvec_iter_advance(bv, iter, bytes, false);
+}
+
+static inline void bvec_iter_advance_mp(const struct bio_vec *bv,
+ struct bvec_iter *iter,
+ unsigned bytes)
+{
+ __bvec_iter_advance(bv, iter, bytes, true);
+}
+
#define for_each_bvec(bvl, bio_vec, iter, start) \
for (iter = (start); \
(iter).bi_size && \
--
2.9.4