On Thu, Nov 15, 2018 at 04:05:10PM -0500, Mike Snitzer wrote: > On Thu, Nov 15 2018 at 3:20pm -0500, > Omar Sandoval <[email protected]> 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 <[email protected]> > > > Cc: Kent Overstreet <[email protected]> > > > Cc: Mike Snitzer <[email protected]> > > > Cc: [email protected] > > > Cc: Alexander Viro <[email protected]> > > > Cc: [email protected] > > > Cc: Shaohua Li <[email protected]> > > > Cc: [email protected] > > > Cc: [email protected] > > > Cc: David Sterba <[email protected]> > > > Cc: [email protected] > > > Cc: Darrick J. Wong <[email protected]> > > > Cc: [email protected] > > > Cc: Gao Xiang <[email protected]> > > > Cc: Christoph Hellwig <[email protected]> > > > Cc: Theodore Ts'o <[email protected]> > > > Cc: [email protected] > > > Cc: Coly Li <[email protected]> > > > Cc: [email protected] > > > Cc: Boaz Harrosh <[email protected]> > > > Cc: Bob Peterson <[email protected]> > > > Cc: [email protected] > > > Signed-off-by: Ming Lei <[email protected]> > > > --- > > > 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.
My only reason to prefer unsigned int is consistency. unsigned int is much more common in the kernel: $ ag --cc -s 'unsigned\s+int' | wc -l 129632 $ ag --cc -s 'unsigned\s+(?!char|short|int|long)' | wc -l 22435 checkpatch also warns on plain unsigned.
