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Message-ID: <20211117043536.GM24307@magnolia>
Date: Tue, 16 Nov 2021 20:35:36 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
Jens Axboe <axboe@...nel.dk>,
Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2 07/28] fs/buffer: Convert __block_write_begin_int() to
take a folio
On Mon, Nov 08, 2021 at 04:05:30AM +0000, Matthew Wilcox (Oracle) wrote:
> There are no plans to convert buffer_head infrastructure to use multi-page
> folios, but __block_write_begin_int() is called from iomap, and it's
> more convenient and less error-prone if we pass in a folio from iomap.
> It also has a nice saving of almost 200 bytes of code from removing
> repeated calls to compound_head().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Pretty straightforward,
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
--D
> ---
> fs/buffer.c | 22 +++++++++++-----------
> fs/internal.h | 2 +-
> fs/iomap/buffered-io.c | 7 +++++--
> 3 files changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 46bc589b7a03..b1d722b26fe9 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1969,34 +1969,34 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
> }
> }
>
> -int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
> +int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
> get_block_t *get_block, const struct iomap *iomap)
> {
> unsigned from = pos & (PAGE_SIZE - 1);
> unsigned to = from + len;
> - struct inode *inode = page->mapping->host;
> + struct inode *inode = folio->mapping->host;
> unsigned block_start, block_end;
> sector_t block;
> int err = 0;
> unsigned blocksize, bbits;
> struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
>
> - BUG_ON(!PageLocked(page));
> + BUG_ON(!folio_test_locked(folio));
> BUG_ON(from > PAGE_SIZE);
> BUG_ON(to > PAGE_SIZE);
> BUG_ON(from > to);
>
> - head = create_page_buffers(page, inode, 0);
> + head = create_page_buffers(&folio->page, inode, 0);
> blocksize = head->b_size;
> bbits = block_size_bits(blocksize);
>
> - block = (sector_t)page->index << (PAGE_SHIFT - bbits);
> + block = (sector_t)folio->index << (PAGE_SHIFT - bbits);
>
> for(bh = head, block_start = 0; bh != head || !block_start;
> block++, block_start=block_end, bh = bh->b_this_page) {
> block_end = block_start + blocksize;
> if (block_end <= from || block_start >= to) {
> - if (PageUptodate(page)) {
> + if (folio_test_uptodate(folio)) {
> if (!buffer_uptodate(bh))
> set_buffer_uptodate(bh);
> }
> @@ -2016,20 +2016,20 @@ int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
>
> if (buffer_new(bh)) {
> clean_bdev_bh_alias(bh);
> - if (PageUptodate(page)) {
> + if (folio_test_uptodate(folio)) {
> clear_buffer_new(bh);
> set_buffer_uptodate(bh);
> mark_buffer_dirty(bh);
> continue;
> }
> if (block_end > to || block_start < from)
> - zero_user_segments(page,
> + folio_zero_segments(folio,
> to, block_end,
> block_start, from);
> continue;
> }
> }
> - if (PageUptodate(page)) {
> + if (folio_test_uptodate(folio)) {
> if (!buffer_uptodate(bh))
> set_buffer_uptodate(bh);
> continue;
> @@ -2050,14 +2050,14 @@ int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
> err = -EIO;
> }
> if (unlikely(err))
> - page_zero_new_buffers(page, from, to);
> + page_zero_new_buffers(&folio->page, from, to);
> return err;
> }
>
> int __block_write_begin(struct page *page, loff_t pos, unsigned len,
> get_block_t *get_block)
> {
> - return __block_write_begin_int(page, pos, len, get_block, NULL);
> + return __block_write_begin_int(page_folio(page), pos, len, get_block, NULL);
> }
> EXPORT_SYMBOL(__block_write_begin);
>
> diff --git a/fs/internal.h b/fs/internal.h
> index cdd83d4899bb..afc13443392b 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -37,7 +37,7 @@ static inline int emergency_thaw_bdev(struct super_block *sb)
> /*
> * buffer.c
> */
> -int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
> +int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
> get_block_t *get_block, const struct iomap *iomap);
>
> /*
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 1753c26c8e76..4e09ea823148 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -597,6 +597,7 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
> const struct iomap_page_ops *page_ops = iter->iomap.page_ops;
> const struct iomap *srcmap = iomap_iter_srcmap(iter);
> struct page *page;
> + struct folio *folio;
> int status = 0;
>
> BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
> @@ -618,11 +619,12 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
> status = -ENOMEM;
> goto out_no_page;
> }
> + folio = page_folio(page);
>
> if (srcmap->type == IOMAP_INLINE)
> status = iomap_write_begin_inline(iter, page);
> else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
> - status = __block_write_begin_int(page, pos, len, NULL, srcmap);
> + status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
> else
> status = __iomap_write_begin(iter, pos, len, page);
>
> @@ -954,11 +956,12 @@ EXPORT_SYMBOL_GPL(iomap_truncate_page);
> static loff_t iomap_page_mkwrite_iter(struct iomap_iter *iter,
> struct page *page)
> {
> + struct folio *folio = page_folio(page);
> loff_t length = iomap_length(iter);
> int ret;
>
> if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) {
> - ret = __block_write_begin_int(page, iter->pos, length, NULL,
> + ret = __block_write_begin_int(folio, iter->pos, length, NULL,
> &iter->iomap);
> if (ret)
> return ret;
> --
> 2.33.0
>
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