| Message ID | 20180609123014.8861-13-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> +static inline unsigned bio_chunks(struct bio *bio) > +{ > + unsigned chunks = 0; > + struct bio_vec bv; > + struct bvec_iter iter; > > - return segs; > + /* > + * We special case discard/write same/write zeroes, because they > + * interpret bi_size differently: > + */ > + switch (bio_op(bio)) { > + case REQ_OP_DISCARD: > + case REQ_OP_SECURE_ERASE: > + case REQ_OP_WRITE_ZEROES: > + return 0; > + case REQ_OP_WRITE_SAME: > + return 1; > + default: > + bio_for_each_chunk(bv, bio, iter) > + chunks++; > + return chunks; Shouldn't this just return bio->bi_vcnt?
On Wed, Jun 13, 2018 at 07:47:41AM -0700, Christoph Hellwig wrote: > > +static inline unsigned bio_chunks(struct bio *bio) > > +{ > > + unsigned chunks = 0; > > + struct bio_vec bv; > > + struct bvec_iter iter; > > > > - return segs; > > + /* > > + * We special case discard/write same/write zeroes, because they > > + * interpret bi_size differently: > > + */ > > + switch (bio_op(bio)) { > > + case REQ_OP_DISCARD: > > + case REQ_OP_SECURE_ERASE: > > + case REQ_OP_WRITE_ZEROES: > > + return 0; > > + case REQ_OP_WRITE_SAME: > > + return 1; > > + default: > > + bio_for_each_chunk(bv, bio, iter) > > + chunks++; > > + return chunks; > > Shouldn't this just return bio->bi_vcnt? No. bio->bi_vcnt is only for the owner of a bio (the code that originally allocated it and filled it out) to use, and really the only legit use is bio_for_each_segment_all() (iterating over segments without using bi_iter because it's already been iterated to the end), and as a convenience thing for bio_add_page. Code that has a bio submitted to it can _not_ use bio->bi_vcnt, it's perfectly legal for it to be 0 (and it is for e.g. bio splits).
diff --git a/include/linux/bio.h b/include/linux/bio.h index c17b8f80d650..13fd7bc30390 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -242,7 +242,6 @@ static inline unsigned bio_segments(struct bio *bio) * We special case discard/write same/write zeroes, because they * interpret bi_size differently: */ - switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: @@ -251,13 +250,34 @@ static inline unsigned bio_segments(struct bio *bio) case REQ_OP_WRITE_SAME: return 1; default: - break; + bio_for_each_segment(bv, bio, iter) + segs++; + return segs; } +} - bio_for_each_segment(bv, bio, iter) - segs++; +static inline unsigned bio_chunks(struct bio *bio) +{ + unsigned chunks = 0; + struct bio_vec bv; + struct bvec_iter iter; - return segs; + /* + * We special case discard/write same/write zeroes, because they + * interpret bi_size differently: + */ + switch (bio_op(bio)) { + case REQ_OP_DISCARD: + case REQ_OP_SECURE_ERASE: + case REQ_OP_WRITE_ZEROES: + return 0; + case REQ_OP_WRITE_SAME: + return 1; + default: + bio_for_each_chunk(bv, bio, iter) + chunks++; + return chunks; + } } /*
There are still cases in which we need to use bio_chunks() for get the number of multipage segment, so introduce it. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- include/linux/bio.h | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-)