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block: Add bio_for_each_folio_all()

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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>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-01-04 10:58:17 -05:00
parent 85f5a74c2b
commit 640d1930be
2 changed files with 53 additions and 1 deletions
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1
Documentation/core-api/kernel-api.rst
View file

@ -279,6 +279,7 @@ Accounting Framework
Block Devices
=============
.. kernel-doc:: include/linux/bio.h
.. kernel-doc:: block/blk-core.c
:export:

53
include/linux/bio.h
View file

@ -166,7 +166,7 @@ static inline void bio_advance(struct bio *bio, unsigned int nbytes)
*/
#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)
@ -260,6 +260,57 @@ 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 */