On Thu, Nov 15 2018 at 3:20pm -0500, Omar Sandoval <osan...@osandov.com> wrote:
> On Thu, Nov 15, 2018 at 04:52:50PM +0800, Ming Lei wrote: > > First it is more efficient to use bio_for_each_bvec() in both > > blk_bio_segment_split() and __blk_recalc_rq_segments() to compute how > > many multi-page bvecs there are in the bio. > > > > Secondly once bio_for_each_bvec() is used, the bvec may need to be > > splitted because its length can be very longer than max segment size, > > so we have to split the big bvec into several segments. > > > > Thirdly when splitting multi-page bvec into segments, the max segment > > limit may be reached, so the bio split need to be considered under > > this situation too. > > > > Cc: Dave Chinner <dchin...@redhat.com> > > Cc: Kent Overstreet <kent.overstr...@gmail.com> > > Cc: Mike Snitzer <snit...@redhat.com> > > Cc: dm-devel@redhat.com > > Cc: Alexander Viro <v...@zeniv.linux.org.uk> > > Cc: linux-fsde...@vger.kernel.org > > Cc: Shaohua Li <s...@kernel.org> > > Cc: linux-r...@vger.kernel.org > > Cc: linux-er...@lists.ozlabs.org > > Cc: David Sterba <dste...@suse.com> > > Cc: linux-bt...@vger.kernel.org > > Cc: Darrick J. Wong <darrick.w...@oracle.com> > > Cc: linux-...@vger.kernel.org > > Cc: Gao Xiang <gaoxian...@huawei.com> > > Cc: Christoph Hellwig <h...@lst.de> > > Cc: Theodore Ts'o <ty...@mit.edu> > > Cc: linux-e...@vger.kernel.org > > Cc: Coly Li <col...@suse.de> > > Cc: linux-bca...@vger.kernel.org > > Cc: Boaz Harrosh <o...@electrozaur.com> > > Cc: Bob Peterson <rpete...@redhat.com> > > Cc: cluster-de...@redhat.com > > Signed-off-by: Ming Lei <ming....@redhat.com> > > --- > > block/blk-merge.c | 90 > > ++++++++++++++++++++++++++++++++++++++++++++++--------- > > 1 file changed, 76 insertions(+), 14 deletions(-) > > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 91b2af332a84..6f7deb94a23f 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -160,6 +160,62 @@ static inline unsigned get_max_io_size(struct > > request_queue *q, > > return sectors; > > } > > > > +/* > > + * Split the bvec @bv into segments, and update all kinds of > > + * variables. > > + */ > > +static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, > > + unsigned *nsegs, unsigned *last_seg_size, > > + unsigned *front_seg_size, unsigned *sectors) > > +{ > > + bool need_split = false; > > + unsigned len = bv->bv_len; > > + unsigned total_len = 0; > > + unsigned new_nsegs = 0, seg_size = 0; > > "unsigned int" here and everywhere else. Curious why? I've wondered what govens use of "unsigned" vs "unsigned int" recently and haven't found _the_ reason to pick one over the other. Thanks, Mike -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel