On Mon, Nov 26, 2018 at 10:17:16AM +0800, Ming Lei wrote:
> This patch pulls the trigger for multi-page bvecs.

Reviewed-by: Omar Sandoval <osan...@fb.com>

> Signed-off-by: Ming Lei <ming....@redhat.com>
> ---
>  block/bio.c         | 22 +++++++++++++++-------
>  fs/iomap.c          |  4 ++--
>  fs/xfs/xfs_aops.c   |  4 ++--
>  include/linux/bio.h |  2 +-
>  4 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 75fde30af51f..8bf9338d4783 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -753,6 +753,8 @@ EXPORT_SYMBOL(bio_add_pc_page);
>   * @page: page to add
>   * @len: length of the data to add
>   * @off: offset of the data in @page
> + * @same_page: if %true only merge if the new data is in the same physical
> + *           page as the last segment of the bio.
>   *
>   * Try to add the data at @page + @off to the last bvec of @bio.  This is a
>   * a useful optimisation for file systems with a block size smaller than the
> @@ -761,19 +763,25 @@ EXPORT_SYMBOL(bio_add_pc_page);
>   * Return %true on success or %false on failure.
>   */
>  bool __bio_try_merge_page(struct bio *bio, struct page *page,
> -             unsigned int len, unsigned int off)
> +             unsigned int len, unsigned int off, bool same_page)
>  {
>       if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
>               return false;
>  
>       if (bio->bi_vcnt > 0) {
>               struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
> +             phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
> +                     bv->bv_offset + bv->bv_len;
> +             phys_addr_t page_addr = page_to_phys(page);
>  
> -             if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) {
> -                     bv->bv_len += len;
> -                     bio->bi_iter.bi_size += len;
> -                     return true;
> -             }
> +             if (vec_end_addr != page_addr + off)
> +                     return false;
> +             if (same_page && ((vec_end_addr - 1) & PAGE_MASK) != page_addr)
> +                     return false;
> +
> +             bv->bv_len += len;
> +             bio->bi_iter.bi_size += len;
> +             return true;
>       }
>       return false;
>  }
> @@ -819,7 +827,7 @@ EXPORT_SYMBOL_GPL(__bio_add_page);
>  int bio_add_page(struct bio *bio, struct page *page,
>                unsigned int len, unsigned int offset)
>  {
> -     if (!__bio_try_merge_page(bio, page, len, offset)) {
> +     if (!__bio_try_merge_page(bio, page, len, offset, false)) {
>               if (bio_full(bio))
>                       return 0;
>               __bio_add_page(bio, page, len, offset);
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 1f648d098a3b..ec5527b0fba4 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -313,7 +313,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, 
> loff_t length, void *data,
>        */
>       sector = iomap_sector(iomap, pos);
>       if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
> -             if (__bio_try_merge_page(ctx->bio, page, plen, poff))
> +             if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
>                       goto done;
>               is_contig = true;
>       }
> @@ -344,7 +344,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, 
> loff_t length, void *data,
>               ctx->bio->bi_end_io = iomap_read_end_io;
>       }
>  
> -     __bio_add_page(ctx->bio, page, plen, poff);
> +     bio_add_page(ctx->bio, page, plen, poff);
>  done:
>       /*
>        * Move the caller beyond our range so that it keeps making progress.
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 1f1829e506e8..b9fd44168f61 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -616,12 +616,12 @@ xfs_add_to_ioend(
>                               bdev, sector);
>       }
>  
> -     if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff)) {
> +     if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
>               if (iop)
>                       atomic_inc(&iop->write_count);
>               if (bio_full(wpc->ioend->io_bio))
>                       xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
> -             __bio_add_page(wpc->ioend->io_bio, page, len, poff);
> +             bio_add_page(wpc->ioend->io_bio, page, len, poff);
>       }
>  
>       wpc->ioend->io_size += len;
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index c35997dd02c2..5505f74aef8b 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -441,7 +441,7 @@ extern int bio_add_page(struct bio *, struct page *, 
> unsigned int,unsigned int);
>  extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page 
> *,
>                          unsigned int, unsigned int);
>  bool __bio_try_merge_page(struct bio *bio, struct page *page,
> -             unsigned int len, unsigned int off);
> +             unsigned int len, unsigned int off, bool same_page);
>  void __bio_add_page(struct bio *bio, struct page *page,
>               unsigned int len, unsigned int off);
>  int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
> -- 
> 2.9.5
> 

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