[PATCH 04/11] block: Add bio_for_each_thp_segment_all

[Matthew Wilcox (Oracle)]

Iterate once for each THP instead of once for each base page.

Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
---
 include/linux/bio.h  | 13 +++++++++++++
 include/linux/bvec.h | 27 +++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index c6d765382926..a0e104910097 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -129,12 +129,25 @@ static inline bool bio_next_segment(const struct bio *bio,
        return true;
 }
 
+static inline bool bio_next_thp_segment(const struct bio *bio,
+                                   struct bvec_iter_all *iter)
+{
+       if (iter->idx >= bio->bi_vcnt)
+               return false;
+
+       bvec_thp_advance(&bio->bi_io_vec[iter->idx], iter);
+       return true;
+}
+
 /*
  * drivers should _never_ use the all version - the bio may have been split
  * before it got to the driver and the driver won't own all of it
  */
 #define bio_for_each_segment_all(bvl, bio, iter) \
        for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
+#define bio_for_each_thp_segment_all(bvl, bio, iter) \
+       for (bvl = bvec_init_iter_all(&iter); \
+            bio_next_thp_segment((bio), &iter); )
 
 static inline void bio_advance_iter(const struct bio *bio,
                                    struct bvec_iter *iter, unsigned int bytes)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index ac0c7299d5b8..ea8a37a7515b 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -162,4 +162,31 @@ static inline void bvec_advance(const struct bio_vec *bvec,
        }
 }
 
+static inline void bvec_thp_advance(const struct bio_vec *bvec,
+                               struct bvec_iter_all *iter_all)
+{
+       struct bio_vec *bv = &iter_all->bv;
+       unsigned int page_size;
+
+       if (iter_all->done) {
+               bv->bv_page += thp_nr_pages(bv->bv_page);
+               page_size = thp_size(bv->bv_page);
+               bv->bv_offset = 0;
+       } else {
+               bv->bv_page = thp_head(bvec->bv_page +
+                               (bvec->bv_offset >> PAGE_SHIFT));
+               page_size = thp_size(bv->bv_page);
+               bv->bv_offset = bvec->bv_offset -
+                               (bv->bv_page - bvec->bv_page) * PAGE_SIZE;
+               BUG_ON(bv->bv_offset >= page_size);
+       }
+       bv->bv_len = min(page_size - bv->bv_offset,
+                        bvec->bv_len - iter_all->done);
+       iter_all->done += bv->bv_len;
+
+       if (iter_all->done == bvec->bv_len) {
+               iter_all->idx++;
+               iter_all->done = 0;
+       }
+}
 #endif /* __LINUX_BVEC_ITER_H */
-- 
2.28.0