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@xxxxxxxxxxxxx>
---
Documentation/core-api/kernel-api.rst | 1 +
include/linux/bio.h | 53 ++++++++++++++++++++++++++-
2 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst
index 2a7444e3a4c2..b804605f705e 100644
--- a/Documentation/core-api/kernel-api.rst
+++ b/Documentation/core-api/kernel-api.rst
@@ -279,6 +279,7 @@ Accounting Framework
Block Devices
=============
+.. kernel-doc:: include/linux/bio.h
.. kernel-doc:: block/blk-core.c
:export:
diff --git a/include/linux/bio.h b/include/linux/bio.h
index ade93e2de6a1..a90a79ad7bd1 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 +314,57 @@ static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
return &bio->bi_io_vec[bio->bi_vcnt - 1];
}
+/**
+ * struct folio_iter - State for iterating all folios in a bio.
+ * @folio: The current folio we're iterating. NULL after the last folio.
+ * @offset: The byte offset within the current folio.
+ * @length: The number of bytes in this iteration (will not cross folio
+ * boundary).
+ */
+struct folio_iter {
+ struct folio *folio;
+ size_t offset;
+ size_t length;
+ /* private: for use by the iterator */
+ 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;
+ }
+}
+
+/**
+ * bio_for_each_folio_all - Iterate over each folio in a bio.
+ * @fi: struct folio_iter which is updated for each folio.
+ * @bio: struct bio to iterate over.
+ */
+#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
