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From:   Yang Shi <shy828301@gmail.com>
Date:   Wed, 6 May 2020 10:59:23 -0700
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Subject: Re: [PATCH v3 02/25] mm: Introduce thp_size
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Apr 29, 2020 at 6:37 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> This is like page_size(), but compiles down to just PAGE_SIZE if THP
> are disabled.  Convert the users of hpage_nr_pages() which would prefer
> this interface.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  drivers/nvdimm/btt.c    | 4 +---
>  drivers/nvdimm/pmem.c   | 6 ++----
>  include/linux/huge_mm.h | 7 +++++++
>  mm/internal.h           | 2 +-
>  mm/page_io.c            | 2 +-
>  mm/page_vma_mapped.c    | 4 ++--
>  6 files changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index 3b09419218d6..78e8d972d45a 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -1488,10 +1488,8 @@ static int btt_rw_page(struct block_device *bdev, sector_t sector,
>  {
>         struct btt *btt = bdev->bd_disk->private_data;
>         int rc;
> -       unsigned int len;
>
> -       len = hpage_nr_pages(page) * PAGE_SIZE;
> -       rc = btt_do_bvec(btt, NULL, page, len, 0, op, sector);
> +       rc = btt_do_bvec(btt, NULL, page, thp_size(page), 0, op, sector);
>         if (rc == 0)
>                 page_endio(page, op_is_write(op), 0);
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 2df6994acf83..184c8b516543 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -235,11 +235,9 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
>         blk_status_t rc;
>
>         if (op_is_write(op))
> -               rc = pmem_do_write(pmem, page, 0, sector,
> -                                  hpage_nr_pages(page) * PAGE_SIZE);
> +               rc = pmem_do_write(pmem, page, 0, sector, tmp_size(page));

s/tmp_size/thp_size

>         else
> -               rc = pmem_do_read(pmem, page, 0, sector,
> -                                  hpage_nr_pages(page) * PAGE_SIZE);
> +               rc = pmem_do_read(pmem, page, 0, sector, thp_size(page));
>         /*
>          * The ->rw_page interface is subtle and tricky.  The core
>          * retries on any error, so we can only invoke page_endio() in
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 6bec4b5b61e1..e944f9757349 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -271,6 +271,11 @@ static inline int hpage_nr_pages(struct page *page)
>         return compound_nr(page);
>  }
>
> +static inline unsigned long thp_size(struct page *page)
> +{
> +       return page_size(page);
> +}
> +
>  struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
>                 pmd_t *pmd, int flags, struct dev_pagemap **pgmap);
>  struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
> @@ -329,6 +334,8 @@ static inline int hpage_nr_pages(struct page *page)
>         return 1;
>  }
>
> +#define thp_size(x)            PAGE_SIZE
> +
>  static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
>  {
>         return false;
> diff --git a/mm/internal.h b/mm/internal.h
> index f762a34b0c57..5efb13d5c226 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -386,7 +386,7 @@ vma_address(struct page *page, struct vm_area_struct *vma)
>         unsigned long start, end;
>
>         start = __vma_address(page, vma);
> -       end = start + PAGE_SIZE * (hpage_nr_pages(page) - 1);
> +       end = start + thp_size(page) - PAGE_SIZE;
>
>         /* page should be within @vma mapping range */
>         VM_BUG_ON_VMA(end < vma->vm_start || start >= vma->vm_end, vma);
> diff --git a/mm/page_io.c b/mm/page_io.c
> index 76965be1d40e..dd935129e3cb 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -41,7 +41,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
>                 bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
>                 bio->bi_end_io = end_io;
>
> -               bio_add_page(bio, page, PAGE_SIZE * hpage_nr_pages(page), 0);
> +               bio_add_page(bio, page, thp_size(page), 0);
>         }
>         return bio;
>  }
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index 719c35246cfa..e65629c056e8 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -227,7 +227,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>                         if (pvmw->address >= pvmw->vma->vm_end ||
>                             pvmw->address >=
>                                         __vma_address(pvmw->page, pvmw->vma) +
> -                                       hpage_nr_pages(pvmw->page) * PAGE_SIZE)
> +                                       thp_size(pvmw->page))
>                                 return not_found(pvmw);
>                         /* Did we cross page table boundary? */
>                         if (pvmw->address % PMD_SIZE == 0) {
> @@ -268,7 +268,7 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
>         unsigned long start, end;
>
>         start = __vma_address(page, vma);
> -       end = start + PAGE_SIZE * (hpage_nr_pages(page) - 1);
> +       end = start + thp_size(page) - PAGE_SIZE;
>
>         if (unlikely(end < vma->vm_start || start >= vma->vm_end))
>                 return 0;
> --
> 2.26.2
>
>