[PATCH v14 091/138] block: Add bio_for_each_folio_all()

Matthew Wilcox (Oracle)
2021-07-15T04:50:07Z

Allow callers to iterate over each folio instead of each page. The
bio need not have been constructed using folios originally.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/bio.h | 43 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index ade93e2de6a1..d462bbc95c4b 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -189,7 +189,7 @@ static inline void bio_advance_iter_single(const struct bio *bio,
*/
#define bio_for_each_bvec_all(bvl, bio, i) \
for (i = 0, bvl = bio_first_bvec_all(bio); \
- i < (bio)->bi_vcnt; i++, bvl++) \
+ i < (bio)->bi_vcnt; i++, bvl++)

#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)

@@ -314,6 +314,47 @@ static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
return &bio->bi_io_vec[bio->bi_vcnt - 1];
}

+struct folio_iter {
+ struct folio *folio;
+ size_t offset;
+ size_t length;
+ size_t _seg_count;
+ int _i;
+};
+
+static inline
+void bio_first_folio(struct folio_iter *fi, struct bio *bio, int i)
+{
+ struct bio_vec *bvec = bio_first_bvec_all(bio) + i;
+
+ fi->folio = page_folio(bvec->bv_page);
+ fi->offset = bvec->bv_offset +
+ PAGE_SIZE * (bvec->bv_page - &fi->folio->page);
+ fi->_seg_count = bvec->bv_len;
+ fi->length = min(folio_size(fi->folio) - fi->offset, fi->_seg_count);
+ fi->_i = i;
+}
+
+static inline void bio_next_folio(struct folio_iter *fi, struct bio *bio)
+{
+ fi->_seg_count -= fi->length;
+ if (fi->_seg_count) {
+ fi->folio = folio_next(fi->folio);
+ fi->offset = 0;
+ fi->length = min(folio_size(fi->folio), fi->_seg_count);
+ } else if (fi->_i + 1 < bio->bi_vcnt) {
+ bio_first_folio(fi, bio, fi->_i + 1);
+ } else {
+ fi->folio = NULL;
+ }
+}
+
+/*
+ * Iterate over each folio in a bio.
+ */
+#define bio_for_each_folio_all(fi, bio) \
+ for (bio_first_folio(&fi, bio, 0); fi.folio; bio_next_folio(&fi, bio))
+
enum bip_flags {
BIP_BLOCK_INTEGRITY = 1 << 0, /* block layer owns integrity data */
BIP_MAPPED_INTEGRITY = 1 << 1, /* ref tag has been remapped */
--
2.30.2