From 8423ae3d7a3cfe084865262cfaeba1359d405182 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Mon, 10 Feb 2014 17:45:50 -0800 Subject: [PATCH] block: Fix cloning of discard/write same bios Immutable biovecs changed the way bio segments are treated in such a way that bio_for_each_segment() cannot now do what we want for discard/write same bios, since bi_size means something completely different for them. Fortunately discard and write same bios never have more than a single biovec, so bio_for_each_segment() is unnecessary and not terribly meaningful for them, but we still have to special case them in a few places. Signed-off-by: Kent Overstreet Tested-by: Richard W.M. Jones Signed-off-by: Jens Axboe --- fs/bio.c | 15 ++++++++++----- include/linux/bio.h | 11 +++++++++++ 2 files changed, 21 insertions(+), 5 deletions(-) diff --git a/fs/bio.c b/fs/bio.c index 75c49a382239..8754e7b6eb49 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -611,7 +611,6 @@ EXPORT_SYMBOL(bio_clone_fast); struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, struct bio_set *bs) { - unsigned nr_iovecs = 0; struct bvec_iter iter; struct bio_vec bv; struct bio *bio; @@ -638,10 +637,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, * __bio_clone_fast() anyways. */ - bio_for_each_segment(bv, bio_src, iter) - nr_iovecs++; - - bio = bio_alloc_bioset(gfp_mask, nr_iovecs, bs); + bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs); if (!bio) return NULL; @@ -650,9 +646,18 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; + if (bio->bi_rw & REQ_DISCARD) + goto integrity_clone; + + if (bio->bi_rw & REQ_WRITE_SAME) { + bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0]; + goto integrity_clone; + } + bio_for_each_segment(bv, bio_src, iter) bio->bi_io_vec[bio->bi_vcnt++] = bv; +integrity_clone: if (bio_integrity(bio_src)) { int ret; diff --git a/include/linux/bio.h b/include/linux/bio.h index d6791bba8264..5a4d39b4686b 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -250,6 +250,17 @@ static inline unsigned bio_segments(struct bio *bio) struct bio_vec bv; struct bvec_iter iter; + /* + * We special case discard/write same, because they interpret bi_size + * differently: + */ + + if (bio->bi_rw & REQ_DISCARD) + return 1; + + if (bio->bi_rw & REQ_WRITE_SAME) + return 1; + bio_for_each_segment(bv, bio, iter) segs++;