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Message-ID: <20210715215105.GM22357@magnolia>
Date: Thu, 15 Jul 2021 14:51:05 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v14 102/138] iomap: Convert iomap_write_begin and
iomap_write_end to folios
On Thu, Jul 15, 2021 at 04:36:28AM +0100, Matthew Wilcox (Oracle) wrote:
> These functions still only work in PAGE_SIZE chunks, but there are
> fewer conversions from head to tail pages as a result of this patch.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
> fs/iomap/buffered-io.c | 68 ++++++++++++++++++++++--------------------
> 1 file changed, 36 insertions(+), 32 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index a3fe0d36c739..5e0aa23d4693 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -541,9 +541,8 @@ static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
>
> static int
> __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
> - struct page *page, struct iomap *srcmap)
> + struct folio *folio, struct iomap *srcmap)
> {
> - struct folio *folio = page_folio(page);
> struct iomap_page *iop = iomap_page_create(inode, folio);
> loff_t block_size = i_blocksize(inode);
> loff_t block_start = round_down(pos, block_size);
> @@ -583,12 +582,14 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
> return 0;
> }
>
> -static int
> -iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> - struct page **pagep, struct iomap *iomap, struct iomap *srcmap)
> +static int iomap_write_begin(struct inode *inode, loff_t pos, size_t len,
> + unsigned flags, struct folio **foliop, struct iomap *iomap,
> + struct iomap *srcmap)
> {
> const struct iomap_page_ops *page_ops = iomap->page_ops;
> + struct folio *folio;
> struct page *page;
> + unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
> int status = 0;
>
> BUG_ON(pos + len > iomap->offset + iomap->length);
> @@ -604,30 +605,31 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> return status;
> }
>
> - page = grab_cache_page_write_begin(inode->i_mapping, pos >> PAGE_SHIFT,
> - AOP_FLAG_NOFS);
> - if (!page) {
> + folio = __filemap_get_folio(inode->i_mapping, pos >> PAGE_SHIFT, fgp,
Ah, ok, so we're moving the file_get_pages flags up to iomap now.
> + mapping_gfp_mask(inode->i_mapping));
> + if (!folio) {
> status = -ENOMEM;
> goto out_no_page;
> }
>
> + page = folio_file_page(folio, pos >> PAGE_SHIFT);
> if (srcmap->type == IOMAP_INLINE)
> iomap_read_inline_data(inode, page, srcmap);
> else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
> status = __block_write_begin_int(page, pos, len, NULL, srcmap);
> else
> - status = __iomap_write_begin(inode, pos, len, flags, page,
> + status = __iomap_write_begin(inode, pos, len, flags, folio,
> srcmap);
>
> if (unlikely(status))
> goto out_unlock;
>
> - *pagep = page;
> + *foliop = folio;
> return 0;
>
> out_unlock:
> - unlock_page(page);
> - put_page(page);
> + folio_unlock(folio);
> + folio_put(folio);
> iomap_write_failed(inode, pos, len);
>
> out_no_page:
> @@ -637,11 +639,10 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> }
>
> static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> - size_t copied, struct page *page)
> + size_t copied, struct folio *folio)
> {
> - struct folio *folio = page_folio(page);
> struct iomap_page *iop = to_iomap_page(folio);
> - flush_dcache_page(page);
> + flush_dcache_folio(folio);
>
> /*
> * The blocks that were entirely written will now be uptodate, so we
> @@ -654,10 +655,10 @@ static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> * uptodate page as a zero-length write, and force the caller to redo
> * the whole thing.
> */
> - if (unlikely(copied < len && !PageUptodate(page)))
> + if (unlikely(copied < len && !folio_test_uptodate(folio)))
> return 0;
> iomap_set_range_uptodate(folio, iop, offset_in_folio(folio, pos), len);
> - __set_page_dirty_nobuffers(page);
> + filemap_dirty_folio(inode->i_mapping, folio);
> return copied;
> }
>
> @@ -680,9 +681,10 @@ static size_t iomap_write_end_inline(struct inode *inode, struct page *page,
>
> /* Returns the number of bytes copied. May be 0. Cannot be an errno. */
> static size_t iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> - size_t copied, struct page *page, struct iomap *iomap,
> + size_t copied, struct folio *folio, struct iomap *iomap,
> struct iomap *srcmap)
> {
> + struct page *page = folio_file_page(folio, pos / PAGE_SIZE);
pos >> PAGE_SHIFT ?
(There's a few more of these elsewhere...)
--D
> const struct iomap_page_ops *page_ops = iomap->page_ops;
> loff_t old_size = inode->i_size;
> size_t ret;
> @@ -693,7 +695,7 @@ static size_t iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
> page, NULL);
> } else {
> - ret = __iomap_write_end(inode, pos, len, copied, page);
> + ret = __iomap_write_end(inode, pos, len, copied, folio);
> }
>
> /*
> @@ -705,13 +707,13 @@ static size_t iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> i_size_write(inode, pos + ret);
> iomap->flags |= IOMAP_F_SIZE_CHANGED;
> }
> - unlock_page(page);
> + folio_unlock(folio);
>
> if (old_size < pos)
> pagecache_isize_extended(inode, old_size, pos);
> if (page_ops && page_ops->page_done)
> page_ops->page_done(inode, pos, ret, page, iomap);
> - put_page(page);
> + folio_put(folio);
>
> if (ret < len)
> iomap_write_failed(inode, pos, len);
> @@ -727,6 +729,7 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> ssize_t written = 0;
>
> do {
> + struct folio *folio;
> struct page *page;
> unsigned long offset; /* Offset into pagecache page */
> unsigned long bytes; /* Bytes to write to page */
> @@ -750,18 +753,19 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> break;
> }
>
> - status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap,
> + status = iomap_write_begin(inode, pos, bytes, 0, &folio, iomap,
> srcmap);
> if (unlikely(status))
> break;
>
> + page = folio_file_page(folio, pos / PAGE_SIZE);
> if (mapping_writably_mapped(inode->i_mapping))
> flush_dcache_page(page);
>
> copied = copy_page_from_iter_atomic(page, offset, bytes, i);
>
> - status = iomap_write_end(inode, pos, bytes, copied, page, iomap,
> - srcmap);
> + status = iomap_write_end(inode, pos, bytes, copied, folio,
> + iomap, srcmap);
>
> if (unlikely(copied != status))
> iov_iter_revert(i, copied - status);
> @@ -825,14 +829,14 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> do {
> unsigned long offset = offset_in_page(pos);
> unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
> - struct page *page;
> + struct folio *folio;
>
> status = iomap_write_begin(inode, pos, bytes,
> - IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap);
> + IOMAP_WRITE_F_UNSHARE, &folio, iomap, srcmap);
> if (unlikely(status))
> return status;
>
> - status = iomap_write_end(inode, pos, bytes, bytes, page, iomap,
> + status = iomap_write_end(inode, pos, bytes, bytes, folio, iomap,
> srcmap);
> if (WARN_ON_ONCE(status == 0))
> return -EIO;
> @@ -871,19 +875,19 @@ EXPORT_SYMBOL_GPL(iomap_file_unshare);
> static s64 iomap_zero(struct inode *inode, loff_t pos, u64 length,
> struct iomap *iomap, struct iomap *srcmap)
> {
> - struct page *page;
> + struct folio *folio;
> int status;
> unsigned offset = offset_in_page(pos);
> unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);
>
> - status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap);
> + status = iomap_write_begin(inode, pos, bytes, 0, &folio, iomap, srcmap);
> if (status)
> return status;
>
> - zero_user(page, offset, bytes);
> - mark_page_accessed(page);
> + zero_user(folio_file_page(folio, pos / PAGE_SIZE), offset, bytes);
> + folio_mark_accessed(folio);
>
> - return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap);
> + return iomap_write_end(inode, pos, bytes, bytes, folio, iomap, srcmap);
> }
>
> static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos,
> --
> 2.30.2
>
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