| Message ID | 20181115085306.9910-6-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: support multi-page bvec | expand |
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 <dchinner@redhat.com> > Cc: Kent Overstreet <kent.overstreet@gmail.com> > Cc: Mike Snitzer <snitzer@redhat.com> > Cc: dm-devel@redhat.com > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: linux-fsdevel@vger.kernel.org > Cc: Shaohua Li <shli@kernel.org> > Cc: linux-raid@vger.kernel.org > Cc: linux-erofs@lists.ozlabs.org > Cc: David Sterba <dsterba@suse.com> > Cc: linux-btrfs@vger.kernel.org > Cc: Darrick J. Wong <darrick.wong@oracle.com> > Cc: linux-xfs@vger.kernel.org > Cc: Gao Xiang <gaoxiang25@huawei.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Theodore Ts'o <tytso@mit.edu> > Cc: linux-ext4@vger.kernel.org > Cc: Coly Li <colyli@suse.de> > Cc: linux-bcache@vger.kernel.org > Cc: Boaz Harrosh <ooo@electrozaur.com> > Cc: Bob Peterson <rpeterso@redhat.com> > Cc: cluster-devel@redhat.com Reviewed-by: Omar Sandoval <osandov@fb.com> Minor comments below. > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > 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 >
> + unsigned last_page = total / PAGE_SIZE; > + > + if (last_page * PAGE_SIZE == total) Not sure it matters much with modern compilers, but generally we shit by PAGE_SHIFT instead of multiplying with or dividing by PAGE_SIZE.
On Thu, Nov 15, 2018 at 03:23:56PM -0800, Omar Sandoval wrote: > 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 <dchinner@redhat.com> > > Cc: Kent Overstreet <kent.overstreet@gmail.com> > > Cc: Mike Snitzer <snitzer@redhat.com> > > Cc: dm-devel@redhat.com > > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > > Cc: linux-fsdevel@vger.kernel.org > > Cc: Shaohua Li <shli@kernel.org> > > Cc: linux-raid@vger.kernel.org > > Cc: linux-erofs@lists.ozlabs.org > > Cc: David Sterba <dsterba@suse.com> > > Cc: linux-btrfs@vger.kernel.org > > Cc: Darrick J. Wong <darrick.wong@oracle.com> > > Cc: linux-xfs@vger.kernel.org > > Cc: Gao Xiang <gaoxiang25@huawei.com> > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Theodore Ts'o <tytso@mit.edu> > > Cc: linux-ext4@vger.kernel.org > > Cc: Coly Li <colyli@suse.de> > > Cc: linux-bcache@vger.kernel.org > > Cc: Boaz Harrosh <ooo@electrozaur.com> > > Cc: Bob Peterson <rpeterso@redhat.com> > > Cc: cluster-devel@redhat.com > > Reviewed-by: Omar Sandoval <osandov@fb.com> > > Minor comments below. > > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > 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. Will fix it. > > > +{ > > + 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; This way is really elegant. Thanks, Ming
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) +{ + unsigned total = bvec->bv_offset + bvec->bv_len; + unsigned last_page = total / PAGE_SIZE; + + if (last_page * PAGE_SIZE == total) + last_page--; + + 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 */
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 <dchinner@redhat.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: dm-devel@redhat.com Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Shaohua Li <shli@kernel.org> Cc: linux-raid@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org Cc: David Sterba <dsterba@suse.com> Cc: linux-btrfs@vger.kernel.org Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: linux-xfs@vger.kernel.org Cc: Gao Xiang <gaoxiang25@huawei.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Theodore Ts'o <tytso@mit.edu> Cc: linux-ext4@vger.kernel.org Cc: Coly Li <colyli@suse.de> Cc: linux-bcache@vger.kernel.org Cc: Boaz Harrosh <ooo@electrozaur.com> Cc: Bob Peterson <rpeterso@redhat.com> Cc: cluster-devel@redhat.com Signed-off-by: Ming Lei <ming.lei@redhat.com> --- include/linux/bvec.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)