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Commit 7bcd79ac authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: bio: introduce helpers to get the 1st and last bvec 



The bio passed to bio_will_gap() may be fast cloned from upper
layer(dm, md, bcache, fs, ...), or from bio splitting in block
core.

Unfortunately bio_will_gap() just figures out the last bvec via
'bi_io_vec[prev->bi_vcnt - 1]' directly, and this way is obviously
wrong.

This patch introduces two helpers for getting the first and last
bvec of one bio for fixing the issue.

Cc: stable@vger.kernel.org
Reported-by: default avatarSagi Grimberg <sagig@dev.mellanox.co.il>
Reviewed-by: default avatarSagi Grimberg <sagig@mellanox.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent e3c2ef41

include/linux/bio.h

+37 −0
Original line number Diff line number Diff line
@@ -310,6 +310,43 @@ static inline void bio_clear_flag(struct bio *bio, unsigned int bit) 
	bio->bi_flags &= ~(1U << bit);

}



static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)

{

	*bv = bio_iovec(bio);

}



static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)

{

	struct bvec_iter iter = bio->bi_iter;

	int idx;



	if (!bio_flagged(bio, BIO_CLONED)) {

		*bv = bio->bi_io_vec[bio->bi_vcnt - 1];

		return;

	}



	if (unlikely(!bio_multiple_segments(bio))) {

		*bv = bio_iovec(bio);

		return;

	}



	bio_advance_iter(bio, &iter, iter.bi_size);



	if (!iter.bi_bvec_done)

		idx = iter.bi_idx - 1;

	else	/* in the middle of bvec */

		idx = iter.bi_idx;



	*bv = bio->bi_io_vec[idx];



	/*

	 * iter.bi_bvec_done records actual length of the last bvec

	 * if this bio ends in the middle of one io vector

	 */

	if (iter.bi_bvec_done)

		bv->bv_len = iter.bi_bvec_done;

}



enum bip_flags {

	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */

	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */