[PATCH 13/32] block: Rework bio_for_each_folio_all()

Kent Overstreet
2023-05-09T16:58:42Z

This reimplements bio_for_each_folio_all() on top of the newly-reworked
bvec_iter_all, and since it's now trivial we also provide
bio_for_each_folio.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: linux-block@vger.kernel.org
---
fs/crypto/bio.c | 9 +++--
fs/iomap/buffered-io.c | 14 ++++---
fs/verity/verify.c | 9 +++--
include/linux/bio.h | 91 +++++++++++++++++++++---------------------
include/linux/bvec.h | 15 +++++--
5 files changed, 75 insertions(+), 63 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index d57d0a020f..6469861add 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -30,11 +30,12 @@
*/
bool fscrypt_decrypt_bio(struct bio *bio)
{
- struct folio_iter fi;
+ struct bvec_iter_all iter;
+ struct folio_vec fv;

- bio_for_each_folio_all(fi, bio) {
- int err = fscrypt_decrypt_pagecache_blocks(fi.folio, fi.length,
- fi.offset);
+ bio_for_each_folio_all(fv, bio, iter) {
+ int err = fscrypt_decrypt_pagecache_blocks(fv.fv_folio, fv.fv_len,
+ fv.fv_offset);

if (err) {
bio->bi_status = errno_to_blk_status(err);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 6f4c97a6d7..60661c87d5 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -187,10 +187,11 @@ static void iomap_finish_folio_read(struct folio *folio, size_t offset,
static void iomap_read_end_io(struct bio *bio)
{
int error = blk_status_to_errno(bio->bi_status);
- struct folio_iter fi;
+ struct bvec_iter_all iter;
+ struct folio_vec fv;

- bio_for_each_folio_all(fi, bio)
- iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
+ bio_for_each_folio_all(fv, bio, iter)
+ iomap_finish_folio_read(fv.fv_folio, fv.fv_offset, fv.fv_len, error);
bio_put(bio);
}

@@ -1328,7 +1329,8 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
u32 folio_count = 0;

for (bio = &ioend->io_inline_bio; bio; bio = next) {
- struct folio_iter fi;
+ struct bvec_iter_all iter;
+ struct folio_vec fv;

/*
* For the last bio, bi_private points to the ioend, so we
@@ -1340,8 +1342,8 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
next = bio->bi_private;

/* walk all folios in bio, ending page IO on them */
- bio_for_each_folio_all(fi, bio) {
- iomap_finish_folio_write(inode, fi.folio, fi.length,
+ bio_for_each_folio_all(fv, bio, iter) {
+ iomap_finish_folio_write(inode, fv.fv_folio, fv.fv_len,
error);
folio_count++;
}
diff --git a/fs/verity/verify.c b/fs/verity/verify.c
index e250822275..b111ab0102 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -340,7 +340,8 @@ void fsverity_verify_bio(struct bio *bio)
struct inode *inode = bio_first_page_all(bio)->mapping->host;
struct fsverity_info *vi = inode->i_verity_info;
struct ahash_request *req;
- struct folio_iter fi;
+ struct bvec_iter_all iter;
+ struct folio_vec fv;
unsigned long max_ra_pages = 0;

/* This allocation never fails, since it's mempool-backed. */
@@ -359,9 +360,9 @@ void fsverity_verify_bio(struct bio *bio)
max_ra_pages = bio->bi_iter.bi_size >> (PAGE_SHIFT + 2);
}

- bio_for_each_folio_all(fi, bio) {
- if (!verify_data_blocks(inode, vi, req, fi.folio, fi.length,
- fi.offset, max_ra_pages)) {
+ bio_for_each_folio_all(fv, bio, iter) {
+ if (!verify_data_blocks(inode, vi, req, fv.fv_folio, fv.fv_len,
+ fv.fv_offset, max_ra_pages)) {
bio->bi_status = BLK_STS_IOERR;
break;
}
diff --git a/include/linux/bio.h b/include/linux/bio.h
index f86c7190c3..7ced281734 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -169,6 +169,42 @@ static inline void bio_advance(struct bio *bio, unsigned int nbytes)
#define bio_for_each_segment(bvl, bio, iter) \
__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)

+struct folio_vec {
+ struct folio *fv_folio;
+ size_t fv_offset;
+ size_t fv_len;
+};
+
+static inline struct folio_vec biovec_to_foliovec(struct bio_vec bv)
+{
+
+ struct folio *folio = page_folio(bv.bv_page);
+ size_t offset = (folio_page_idx(folio, bv.bv_page) << PAGE_SHIFT) +
+ bv.bv_offset;
+ size_t len = min_t(size_t, folio_size(folio) - offset, bv.bv_len);
+
+ return (struct folio_vec) {
+ .fv_folio = folio,
+ .fv_offset = offset,
+ .fv_len = len,
+ };
+}
+
+static inline struct folio_vec bio_iter_iovec_folio(struct bio *bio,
+ struct bvec_iter iter)
+{
+ return biovec_to_foliovec(bio_iter_iovec(bio, iter));
+}
+
+#define __bio_for_each_folio(bvl, bio, iter, start) \
+ for (iter = (start); \
+ (iter).bi_size && \
+ ((bvl = bio_iter_iovec_folio((bio), (iter))), 1); \
+ bio_advance_iter_single((bio), &(iter), (bvl).fv_len))
+
+#define bio_for_each_folio(bvl, bio, iter) \
+ __bio_for_each_folio(bvl, bio, iter, (bio)->bi_iter)
+
#define __bio_for_each_bvec(bvl, bio, iter, start) \
for (iter = (start); \
(iter).bi_size && \
@@ -277,59 +313,22 @@ 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 */
- struct folio *_next;
- 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->_next = folio_next(fi->folio);
- fi->_i = i;
-}
-
-static inline void bio_next_folio(struct folio_iter *fi, struct bio *bio)
+static inline struct folio_vec bio_folio_iter_all_peek(const struct bio *bio,
+ const struct bvec_iter_all *iter)
{
- fi->_seg_count -= fi->length;
- if (fi->_seg_count) {
- fi->folio = fi->_next;
- fi->offset = 0;
- fi->length = min(folio_size(fi->folio), fi->_seg_count);
- fi->_next = folio_next(fi->folio);
- } else if (fi->_i + 1 < bio->bi_vcnt) {
- bio_first_folio(fi, bio, fi->_i + 1);
- } else {
- fi->folio = NULL;
- }
+ return biovec_to_foliovec(__bvec_iter_all_peek(bio->bi_io_vec, iter));
}

/**
* bio_for_each_folio_all - Iterate over each folio in a bio.
- * @fi: struct folio_iter which is updated for each folio.
+ * @fi: struct bio_folio_iter_all 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))
+#define bio_for_each_folio_all(fv, bio, iter) \
+ for (bvec_iter_all_init(&iter); \
+ iter.idx < bio->bi_vcnt && \
+ ((fv = bio_folio_iter_all_peek(bio, &iter)), true); \
+ bio_iter_all_advance((bio), &iter, fv.fv_len))

enum bip_flags {
BIP_BLOCK_INTEGRITY = 1 << 0, /* block layer owns integrity data */
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 635fb54143..d238f959e3 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -205,18 +205,27 @@ static inline void bvec_iter_all_init(struct bvec_iter_all *iter_all)
iter_all->idx = 0;
}

-static inline struct bio_vec bvec_iter_all_peek(const struct bio_vec *bvec,
- struct bvec_iter_all *iter)
+static inline struct bio_vec __bvec_iter_all_peek(const struct bio_vec *bvec,
+ const struct bvec_iter_all *iter)
{
struct bio_vec bv = bvec[iter->idx];

+ BUG_ON(iter->done >= bv.bv_len);
+
bv.bv_offset += iter->done;
bv.bv_len -= iter->done;

bv.bv_page += bv.bv_offset >> PAGE_SHIFT;
bv.bv_offset &= ~PAGE_MASK;
- bv.bv_len = min_t(unsigned, PAGE_SIZE - bv.bv_offset, bv.bv_len);
+ return bv;
+}
+
+static inline struct bio_vec bvec_iter_all_peek(const struct bio_vec *bvec,
+ const struct bvec_iter_all *iter)
+{
+ struct bio_vec bv = __bvec_iter_all_peek(bvec, iter);

+ bv.bv_len = min_t(unsigned, PAGE_SIZE - bv.bv_offset, bv.bv_len);
return bv;
}

--
2.40.1