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Date: Sun, 05 Mar 2023 16:48:32 +0530
From: Ritesh Harjani (IBM) <ritesh.list@...il.com>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
Theodore Tso <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 03/31] ext4: Convert ext4_bio_write_page() to use a folio
"Matthew Wilcox (Oracle)" <willy@...radead.org> writes:
> Remove several calls to compound_head() and the last caller of
> set_page_writeback_keepwrite(), so remove the wrapper too.
Straight forward conversion.
Looks good to me. Please feel free to add -
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
> fs/ext4/page-io.c | 58 ++++++++++++++++++--------------------
> include/linux/page-flags.h | 5 ----
> 2 files changed, 27 insertions(+), 36 deletions(-)
>
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index beaec6d81074..982791050892 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -409,11 +409,9 @@ static void io_submit_init_bio(struct ext4_io_submit *io,
>
> static void io_submit_add_bh(struct ext4_io_submit *io,
> struct inode *inode,
> - struct page *page,
> + struct folio *folio,
> struct buffer_head *bh)
> {
> - int ret;
> -
> if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
> !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
> submit_and_retry:
> @@ -421,10 +419,9 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
> }
> if (io->io_bio == NULL)
> io_submit_init_bio(io, bh);
> - ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
> - if (ret != bh->b_size)
> + if (!bio_add_folio(io->io_bio, folio, bh->b_size, bh_offset(bh)))
> goto submit_and_retry;
> - wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size);
> + wbc_account_cgroup_owner(io->io_wbc, &folio->page, bh->b_size);
> io->io_next_block++;
> }
>
> @@ -432,8 +429,9 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> struct page *page,
> int len)
> {
> - struct page *bounce_page = NULL;
> - struct inode *inode = page->mapping->host;
> + struct folio *folio = page_folio(page);
> + struct folio *io_folio = folio;
> + struct inode *inode = folio->mapping->host;
> unsigned block_start;
> struct buffer_head *bh, *head;
> int ret = 0;
> @@ -441,30 +439,30 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> struct writeback_control *wbc = io->io_wbc;
> bool keep_towrite = false;
>
> - BUG_ON(!PageLocked(page));
> - BUG_ON(PageWriteback(page));
> + BUG_ON(!folio_test_locked(folio));
> + BUG_ON(folio_test_writeback(folio));
>
> - ClearPageError(page);
> + folio_clear_error(folio);
>
> /*
> * Comments copied from block_write_full_page:
> *
> - * The page straddles i_size. It must be zeroed out on each and every
> + * The folio straddles i_size. It must be zeroed out on each and every
> * writepage invocation because it may be mmapped. "A file is mapped
> * in multiples of the page size. For a file that is not a multiple of
> * the page size, the remaining memory is zeroed when mapped, and
> * writes to that region are not written out to the file."
> */
> - if (len < PAGE_SIZE)
> - zero_user_segment(page, len, PAGE_SIZE);
> + if (len < folio_size(folio))
> + folio_zero_segment(folio, len, folio_size(folio));
> /*
> * In the first loop we prepare and mark buffers to submit. We have to
> - * mark all buffers in the page before submitting so that
> - * end_page_writeback() cannot be called from ext4_end_bio() when IO
> + * mark all buffers in the folio before submitting so that
> + * folio_end_writeback() cannot be called from ext4_end_bio() when IO
> * on the first buffer finishes and we are still working on submitting
> * the second buffer.
> */
> - bh = head = page_buffers(page);
> + bh = head = folio_buffers(folio);
> do {
> block_start = bh_offset(bh);
> if (block_start >= len) {
> @@ -479,14 +477,14 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> clear_buffer_dirty(bh);
> /*
> * Keeping dirty some buffer we cannot write? Make sure
> - * to redirty the page and keep TOWRITE tag so that
> - * racing WB_SYNC_ALL writeback does not skip the page.
> + * to redirty the folio and keep TOWRITE tag so that
> + * racing WB_SYNC_ALL writeback does not skip the folio.
> * This happens e.g. when doing writeout for
> * transaction commit.
> */
> if (buffer_dirty(bh)) {
> - if (!PageDirty(page))
> - redirty_page_for_writepage(wbc, page);
> + if (!folio_test_dirty(folio))
> + folio_redirty_for_writepage(wbc, folio);
> keep_towrite = true;
> }
> continue;
> @@ -498,11 +496,11 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> nr_to_submit++;
> } while ((bh = bh->b_this_page) != head);
>
> - /* Nothing to submit? Just unlock the page... */
> + /* Nothing to submit? Just unlock the folio... */
> if (!nr_to_submit)
> goto unlock;
>
> - bh = head = page_buffers(page);
> + bh = head = folio_buffers(folio);
>
> /*
> * If any blocks are being written to an encrypted file, encrypt them
> @@ -514,6 +512,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
> gfp_t gfp_flags = GFP_NOFS;
> unsigned int enc_bytes = round_up(len, i_blocksize(inode));
> + struct page *bounce_page;
>
> /*
> * Since bounce page allocation uses a mempool, we can only use
> @@ -540,7 +539,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> }
>
> printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
> - redirty_page_for_writepage(wbc, page);
> + folio_redirty_for_writepage(wbc, folio);
> do {
> if (buffer_async_write(bh)) {
> clear_buffer_async_write(bh);
> @@ -550,21 +549,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
> } while (bh != head);
> goto unlock;
> }
> + io_folio = page_folio(bounce_page);
> }
>
> - if (keep_towrite)
> - set_page_writeback_keepwrite(page);
> - else
> - set_page_writeback(page);
> + __folio_start_writeback(folio, keep_towrite);
>
> /* Now submit buffers to write */
> do {
> if (!buffer_async_write(bh))
> continue;
> - io_submit_add_bh(io, inode,
> - bounce_page ? bounce_page : page, bh);
> + io_submit_add_bh(io, inode, io_folio, bh);
> } while ((bh = bh->b_this_page) != head);
> unlock:
> - unlock_page(page);
> + folio_unlock(folio);
> return ret;
> }
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 0425f22a9c82..bba2a32031a2 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -766,11 +766,6 @@ bool set_page_writeback(struct page *page);
> #define folio_start_writeback_keepwrite(folio) \
> __folio_start_writeback(folio, true)
>
> -static inline void set_page_writeback_keepwrite(struct page *page)
> -{
> - folio_start_writeback_keepwrite(page_folio(page));
> -}
> -
> static inline bool test_set_page_writeback(struct page *page)
> {
> return set_page_writeback(page);
> --
> 2.35.1
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