On Thu, Nov 15, 2018 at 04:52:52PM +0800, Ming Lei wrote: > BTRFS and guard_bio_eod() need to get the last singlepage segment > from one multipage bvec, so introduce this helper to make them happy. > > 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]
Reviewed-by: Omar Sandoval <[email protected]> Minor comments below. > Signed-off-by: Ming Lei <[email protected]> > --- > include/linux/bvec.h | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/include/linux/bvec.h b/include/linux/bvec.h > index 3d61352cd8cf..01616a0b6220 100644 > --- a/include/linux/bvec.h > +++ b/include/linux/bvec.h > @@ -216,4 +216,29 @@ static inline bool mp_bvec_iter_advance(const struct > bio_vec *bv, > .bi_bvec_done = 0, \ > } > > +/* > + * Get the last singlepage segment from the multipage bvec and store it > + * in @seg > + */ > +static inline void bvec_last_segment(const struct bio_vec *bvec, > + struct bio_vec *seg) Indentation is all messed up here. > +{ > + unsigned total = bvec->bv_offset + bvec->bv_len; > + unsigned last_page = total / PAGE_SIZE; > + > + if (last_page * PAGE_SIZE == total) > + last_page--; I think this could just be unsigned int last_page = (total - 1) / PAGE_SIZE; > + seg->bv_page = nth_page(bvec->bv_page, last_page); > + > + /* the whole segment is inside the last page */ > + if (bvec->bv_offset >= last_page * PAGE_SIZE) { > + seg->bv_offset = bvec->bv_offset % PAGE_SIZE; > + seg->bv_len = bvec->bv_len; > + } else { > + seg->bv_offset = 0; > + seg->bv_len = total - last_page * PAGE_SIZE; > + } > +} > + > #endif /* __LINUX_BVEC_ITER_H */ > -- > 2.9.5 >
