Re: [PATCH v3 05/49] fs/buffer: comment on direct access to bvec table

From	Christoph Hellwig <hch@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 05/49] fs/buffer: comment on direct access to bvec table
Date	2017-08-10 13:20 +0200
Message-ID	<ucTFn-4RQ-3@gated-at.bofh.it> (permalink)
References	<uc8n7-5sU-3@gated-at.bofh.it> <uc8n9-5sU-39@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> +	/*
> +	 * It is safe to truncate the last bvec in the following way
> +	 * even though multipage bvec is supported, but we need to
> +	 * fix the parameters passed to zero_user().
> +	 */
> +	struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];

A 'we need to fix XXX' comment isn't very useful.  Just fix it in the
series (which I suspect you're going to do anyway).

Also a bio_last_vec helper might be nice for something like this and
documents properly converted places much better than these comments.

Thread

[PATCH v3 00/49] block: support multipage bvec Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 10/49] dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
    Re: [PATCH v3 10/49] dm: limit the max bio size as BIO_MAX_PAGES *  PAGE_SIZE Christoph Hellwig <hch@infradead.org> - 2017-08-10 13:30 +0200
  [PATCH v3 13/49] btrfs: comment on direct access bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 08/49] block: comment on bio_alloc_pages() Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 09/49] block: comment on bio_iov_iter_get_pages() Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
    Re: [PATCH v3 09/49] block: comment on bio_iov_iter_get_pages() Christoph Hellwig <hch@infradead.org> - 2017-08-10 13:30 +0200
  [PATCH v3 07/49] bcache: comment on direct access to bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
    Re: [PATCH v3 07/49] bcache: comment on direct access to bvec table Coly Li <i@coly.li> - 2017-08-08 14:40 +0200
    Re: [PATCH v3 07/49] bcache: comment on direct access to bvec table Christoph Hellwig <hch@infradead.org> - 2017-08-10 13:30 +0200
  [PATCH v3 05/49] fs/buffer: comment on direct access to bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
    Re: [PATCH v3 05/49] fs/buffer: comment on direct access to bvec  table Christoph Hellwig <hch@infradead.org> - 2017-08-10 13:20 +0200
  [PATCH v3 12/49] btrfs: avoid to access bvec table directly for a cloned bio Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 03/49] kernel/power/swap.c: comment on direct access to bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 02/49] block: loop: comment on direct access to bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 16/49] block: bounce: don't access bio->bi_io_vec in copy_to_high_bio_irq Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 15/49] bvec_iter: introduce BVEC_ITER_ALL_INIT Ming Lei <ming.lei@redhat.com> - 2017-08-08 10:50 +0200
  [PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp() "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-08 18:40 +0200
  [PATCH v3 48/49] block: enable multipage bvecs Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 33/49] bcache: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 33/49] bcache: convert to bio_for_each_segment_all_sp() Coly Li <i@coly.li> - 2017-08-08 14:40 +0200
  [PATCH v3 49/49] block: bio: pass segments to bio if bio_add_page() is bypassed Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 25/49] block: use bio_for_each_segment_mp() to map sg Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 37/49] fs/mpage: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 37/49] fs/mpage: convert to  bio_for_each_segment_all_sp() Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:20 +0200
  [PATCH v3 28/49] block: introduce bvec_get_last_page() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 34/49] md: raid1: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 26/49] block: introduce bvec_for_each_sp_bvec() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 44/49] exofs: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 35/49] dm-crypt: don't clear bvec->bv_page in crypt_free_buffer_pages() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 42/49] gfs2: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 32/49] block: convert to singe/multi page version of bio_for_each_segment_all() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 39/49] fs/iomap: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 29/49] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 21/49] blk-merge: compute bio->bi_seg_front_size efficiently Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 21/49] blk-merge: compute bio->bi_seg_front_size  efficiently Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:30 +0200
  [PATCH v3 24/49] block: use bio_for_each_segment_mp() to compute segments count Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 43/49] f2fs: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 23/49] block: blk-merge: remove unnecessary check Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 23/49] block: blk-merge: remove unnecessary check Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:20 +0200
  [PATCH v3 27/49] block: bio: introduce single/multi page version of bio_for_each_segment_all() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 46/49] fs/btrfs: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 46/49] fs/btrfs: convert to bio_for_each_segment_all_sp() Filipe Manana <fdmanana@gmail.com> - 2017-08-08 11:10 +0200
  [PATCH v3 38/49] fs/block: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 18/49] block: introduce multipage/single page bvec helpers Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 18/49] block: introduce multipage/single page bvec  helpers Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:10 +0200
  [PATCH v3 47/49] fs/direct-io: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 31/49] block: deal with dirtying pages for multipage bvec Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 20/49] block: introduce bio_for_each_segment_mp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 20/49] block: introduce bio_for_each_segment_mp() Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:30 +0200
  [PATCH v3 45/49] fs: crypto: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 40/49] ext4: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 22/49] block: blk-merge: try to make front segments in full size Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 22/49] block: blk-merge: try to make front segments in  full size Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:30 +0200
  [PATCH v3 30/49] btrfs: use bvec_get_last_page to get bio's last page Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 36/49] dm-crypt: convert to bio_for_each_segment_all_sp() Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
  [PATCH v3 19/49] block: implement sp version of bvec iterator helpers Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:00 +0200
    Re: [PATCH v3 19/49] block: implement sp version of bvec iterator  helpers Christoph Hellwig <hch@infradead.org> - 2017-08-10 14:10 +0200
  [PATCH v3 04/49] mm: page_io.c: comment on direct access to bvec table Ming Lei <ming.lei@redhat.com> - 2017-08-08 11:10 +0200
    Re: [PATCH v3 04/49] mm: page_io.c: comment on direct access to bvec  table Christoph Hellwig <hch@infradead.org> - 2017-08-10 13:20 +0200

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