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authorMing Lei <ming.lei@canonical.com>2016-02-26 23:40:50 +0800
committerJens Axboe <axboe@fb.com>2016-03-03 14:42:49 -0700
commit7bcd79ac50d9d83350a835bdb91c04ac9e098412 (patch)
treeb8161854b8ec9825e7b9fabf2299231130eaf574 /include
parente3c2ef41f88e50c8557270868600d3132028af3b (diff)
downloadlwn-7bcd79ac50d9d83350a835bdb91c04ac9e098412.tar.gz
lwn-7bcd79ac50d9d83350a835bdb91c04ac9e098412.zip
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: 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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/bio.h37
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 5349e6816cbb..cb6888824108 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -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 */