bio: optimise bvec iteration

__bio_for_each_bvec(), __bio_for_each_segment() and bio_copy_data_iter()
fall under conditions of bvec_iter_advance_single(), which is a faster
and slimmer version of bvec_iter_advance(). Add
bio_advance_iter_single() and convert them.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index ebb1813..1f2cc1f 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1212,8 +1212,8 @@ void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 
                flush_dcache_page(dst_bv.bv_page);
 
-               bio_advance_iter(src, src_iter, bytes);
-               bio_advance_iter(dst, dst_iter, bytes);
+               bio_advance_iter_single(src, src_iter, bytes);
+               bio_advance_iter_single(dst, dst_iter, bytes);
        }
 }
 EXPORT_SYMBOL(bio_copy_data_iter);

diff --git a/include/linux/bio.h b/include/linux/bio.h
index ecf6710..1edda61 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -148,11 +148,24 @@ static inline void bio_advance_iter(const struct bio *bio,
                /* TODO: It is reasonable to complete bio with error here. */
 }
 
+/* @bytes should be less or equal to bvec[i->bi_idx].bv_len */
+static inline void bio_advance_iter_single(const struct bio *bio,
+                                          struct bvec_iter *iter,
+                                          unsigned int bytes)
+{
+       iter->bi_sector += bytes >> 9;
+
+       if (bio_no_advance_iter(bio))
+               iter->bi_size -= bytes;
+       else
+               bvec_iter_advance_single(bio->bi_io_vec, iter, bytes);
+}
+
 #define __bio_for_each_segment(bvl, bio, iter, start)                  \
        for (iter = (start);                                            \
             (iter).bi_size &&                                          \
                ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
-            bio_advance_iter((bio), &(iter), (bvl).bv_len))
+            bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
 
 #define bio_for_each_segment(bvl, bio, iter)                           \
        __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
@@ -161,7 +174,7 @@ static inline void bio_advance_iter(const struct bio *bio,
        for (iter = (start);                                            \
             (iter).bi_size &&                                          \
                ((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
-            bio_advance_iter((bio), &(iter), (bvl).bv_len))
+            bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
 
 /* iterate over multi-page bvec */
 #define bio_for_each_bvec(bvl, bio, iter)                      \