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| author | Ming Lei <ming.lei@canonical.com> | 2016-02-26 23:40:50 +0800 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-03-13 13:53:41 -0400 |
| commit | 13dd5b79a6c0c3991ccee05b79722e0a38f3f6ae (patch) | |
| tree | 02feaa904f9b1e209fabe9b255b30eb2d31b52e4 | |
| parent | 8894187f19fd8920f9baee50691ef2f20724bb66 (diff) | |
| download | lwn-13dd5b79a6c0c3991ccee05b79722e0a38f3f6ae.tar.gz lwn-13dd5b79a6c0c3991ccee05b79722e0a38f3f6ae.zip | |
block: bio: introduce helpers to get the 1st and last bvec
[ Upstream commit 7bcd79ac50d9d83350a835bdb91c04ac9e098412 ]
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: Sagi Grimberg <sagig@dev.mellanox.co.il>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | include/linux/bio.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 7347f486ceca..08ce93ede229 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -292,6 +292,43 @@ static inline unsigned bio_segments(struct bio *bio) */ #define bio_get(bio) atomic_inc(&(bio)->bi_cnt) +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 */ |