[PATCH 0/7] More filesystem folio conversions for 6.6

[PATCH 0/7] More filesystem folio conversions for 6.6

[Matthew Wilcox (Oracle)]

Remove the only spots in affs which actually use a struct page; there
are a few places where one is mentioned, but it's part of the interface.

The rest of this is removing the remaining calls to set_bh_page(),
and then removing the function before any new users show up.

Matthew Wilcox (Oracle) (7):
  highmem: Add memcpy_to_folio() and memcpy_from_folio()
  affs: Convert affs_symlink_read_folio() to use the folio
  affs: Convert data read and write to use folios
  migrate: Use folio_set_bh() instead of set_bh_page()
  ntfs3: Convert ntfs_get_block_vbo() to use a folio
  jbd2: Use a folio in jbd2_journal_write_metadata_buffer()
  buffer: Remove set_bh_page()

 fs/affs/file.c              | 77 ++++++++++++++++++-------------------
 fs/affs/symlink.c           | 12 +++---
 fs/buffer.c                 | 15 --------
 fs/jbd2/journal.c           | 35 ++++++++---------
 fs/ntfs3/inode.c            | 10 ++---
 include/linux/buffer_head.h |  2 -
 include/linux/highmem.h     | 44 +++++++++++++++++++++
 mm/migrate.c                |  2 +-
 8 files changed, 109 insertions(+), 88 deletions(-)

-- 
2.39.2

[PATCH 1/7] highmem: Add memcpy_to_folio() and memcpy_from_folio()

[Matthew Wilcox (Oracle)]

These are the folio equivalent of memcpy_to_page() and memcpy_from_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/highmem.h | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 68da30625a6c..0280f57d4744 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -439,6 +439,50 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len)
 	kunmap_local(addr);
 }
 
+static inline void memcpy_from_folio(char *to, struct folio *folio,
+		size_t offset, size_t len)
+{
+	VM_BUG_ON(offset + len > folio_size(folio));
+
+	do {
+		char *from = kmap_local_folio(folio, offset);
+		size_t chunk = len;
+
+		if (folio_test_highmem(folio) &&
+		    (chunk > (PAGE_SIZE - offset_in_page(offset))))
+			chunk = PAGE_SIZE - offset_in_page(offset);
+		memcpy(to, from, len);
+		kunmap_local(from);
+
+		from += chunk;
+		offset += chunk;
+		len -= chunk;
+	} while (len > 0);
+}
+
+static inline void memcpy_to_folio(struct folio *folio, size_t offset,
+		const char *from, size_t len)
+{
+	VM_BUG_ON(offset + len > folio_size(folio));
+
+	do {
+		char *to = kmap_local_folio(folio, offset);
+		size_t chunk = len;
+
+		if (folio_test_highmem(folio) &&
+		    (chunk > (PAGE_SIZE - offset_in_page(offset))))
+			chunk = PAGE_SIZE - offset_in_page(offset);
+		memcpy(to, from, len);
+		kunmap_local(to);
+
+		from += chunk;
+		offset += chunk;
+		len -= chunk;
+	} while (len > 0);
+
+	flush_dcache_folio(folio);
+}
+
 /**
  * memcpy_from_file_folio - Copy some bytes from a file folio.
  * @to: The destination buffer.
-- 
2.39.2

[PATCH 2/7] affs: Convert affs_symlink_read_folio() to use the folio

[Matthew Wilcox (Oracle)]

Remove use of the old page APIs.  That includes use of setting PageError
on error; simply not setting the uptodate flag is sufficient.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/affs/symlink.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/affs/symlink.c b/fs/affs/symlink.c
index 31d6446dc166..094aec8d17b8 100644
--- a/fs/affs/symlink.c
+++ b/fs/affs/symlink.c
@@ -13,10 +13,9 @@
 
 static int affs_symlink_read_folio(struct file *file, struct folio *folio)
 {
-	struct page *page = &folio->page;
 	struct buffer_head *bh;
-	struct inode *inode = page->mapping->host;
-	char *link = page_address(page);
+	struct inode *inode = folio->mapping->host;
+	char *link = folio_address(folio);
 	struct slink_front *lf;
 	int			 i, j;
 	char			 c;
@@ -58,12 +57,11 @@ static int affs_symlink_read_folio(struct file *file, struct folio *folio)
 	}
 	link[i] = '\0';
 	affs_brelse(bh);
-	SetPageUptodate(page);
-	unlock_page(page);
+	folio_mark_uptodate(folio);
+	folio_unlock(folio);
 	return 0;
 fail:
-	SetPageError(page);
-	unlock_page(page);
+	folio_unlock(folio);
 	return -EIO;
 }
 
-- 
2.39.2

[PATCH 3/7] affs: Convert data read and write to use folios

[Matthew Wilcox (Oracle)]

We still need to convert to/from folios in write_begin & write_end
to fit the API, but this removes a lot of calls to old page-based
functions, removing many hidden calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/affs/file.c | 77 +++++++++++++++++++++++++-------------------------
 1 file changed, 38 insertions(+), 39 deletions(-)

diff --git a/fs/affs/file.c b/fs/affs/file.c
index e43f2f007ac1..705e227ff63d 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -520,21 +520,20 @@ affs_getemptyblk_ino(struct inode *inode, int block)
 	return ERR_PTR(err);
 }
 
-static int
-affs_do_readpage_ofs(struct page *page, unsigned to, int create)
+static int affs_do_read_folio_ofs(struct folio *folio, size_t to, int create)
 {
-	struct inode *inode = page->mapping->host;
+	struct inode *inode = folio->mapping->host;
 	struct super_block *sb = inode->i_sb;
 	struct buffer_head *bh;
-	unsigned pos = 0;
-	u32 bidx, boff, bsize;
+	size_t pos = 0;
+	size_t bidx, boff, bsize;
 	u32 tmp;
 
-	pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
-		 page->index, to);
-	BUG_ON(to > PAGE_SIZE);
+	pr_debug("%s(%lu, %ld, 0, %zu)\n", __func__, inode->i_ino,
+		 folio->index, to);
+	BUG_ON(to > folio_size(folio));
 	bsize = AFFS_SB(sb)->s_data_blksize;
-	tmp = page->index << PAGE_SHIFT;
+	tmp = folio_pos(folio);
 	bidx = tmp / bsize;
 	boff = tmp % bsize;
 
@@ -544,7 +543,7 @@ affs_do_readpage_ofs(struct page *page, unsigned to, int create)
 			return PTR_ERR(bh);
 		tmp = min(bsize - boff, to - pos);
 		BUG_ON(pos + tmp > to || tmp > bsize);
-		memcpy_to_page(page, pos, AFFS_DATA(bh) + boff, tmp);
+		memcpy_to_folio(folio, pos, AFFS_DATA(bh) + boff, tmp);
 		affs_brelse(bh);
 		bidx++;
 		pos += tmp;
@@ -624,25 +623,23 @@ affs_extent_file_ofs(struct inode *inode, u32 newsize)
 	return PTR_ERR(bh);
 }
 
-static int
-affs_read_folio_ofs(struct file *file, struct folio *folio)
+static int affs_read_folio_ofs(struct file *file, struct folio *folio)
 {
-	struct page *page = &folio->page;
-	struct inode *inode = page->mapping->host;
-	u32 to;
+	struct inode *inode = folio->mapping->host;
+	size_t to;
 	int err;
 
-	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
-	to = PAGE_SIZE;
-	if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
-		to = inode->i_size & ~PAGE_MASK;
-		memset(page_address(page) + to, 0, PAGE_SIZE - to);
+	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, folio->index);
+	to = folio_size(folio);
+	if (folio_pos(folio) + to > inode->i_size) {
+		to = inode->i_size - folio_pos(folio);
+		folio_zero_segment(folio, to, folio_size(folio));
 	}
 
-	err = affs_do_readpage_ofs(page, to, 0);
+	err = affs_do_read_folio_ofs(folio, to, 0);
 	if (!err)
-		SetPageUptodate(page);
-	unlock_page(page);
+		folio_mark_uptodate(folio);
+	folio_unlock(folio);
 	return err;
 }
 
@@ -651,7 +648,7 @@ static int affs_write_begin_ofs(struct file *file, struct address_space *mapping
 				struct page **pagep, void **fsdata)
 {
 	struct inode *inode = mapping->host;
-	struct page *page;
+	struct folio *folio;
 	pgoff_t index;
 	int err = 0;
 
@@ -667,19 +664,20 @@ static int affs_write_begin_ofs(struct file *file, struct address_space *mapping
 	}
 
 	index = pos >> PAGE_SHIFT;
-	page = grab_cache_page_write_begin(mapping, index);
-	if (!page)
-		return -ENOMEM;
-	*pagep = page;
+	folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
+			mapping_gfp_mask(mapping));
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
+	*pagep = &folio->page;
 
-	if (PageUptodate(page))
+	if (folio_test_uptodate(folio))
 		return 0;
 
 	/* XXX: inefficient but safe in the face of short writes */
-	err = affs_do_readpage_ofs(page, PAGE_SIZE, 1);
+	err = affs_do_read_folio_ofs(folio, folio_size(folio), 1);
 	if (err) {
-		unlock_page(page);
-		put_page(page);
+		folio_unlock(folio);
+		folio_put(folio);
 	}
 	return err;
 }
@@ -688,6 +686,7 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned copied,
 				struct page *page, void *fsdata)
 {
+	struct folio *folio = page_folio(page);
 	struct inode *inode = mapping->host;
 	struct super_block *sb = inode->i_sb;
 	struct buffer_head *bh, *prev_bh;
@@ -701,18 +700,18 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 	to = from + len;
 	/*
 	 * XXX: not sure if this can handle short copies (len < copied), but
-	 * we don't have to, because the page should always be uptodate here,
+	 * we don't have to, because the folio should always be uptodate here,
 	 * due to write_begin.
 	 */
 
 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
 		 pos + len);
 	bsize = AFFS_SB(sb)->s_data_blksize;
-	data = page_address(page);
+	data = folio_address(folio);
 
 	bh = NULL;
 	written = 0;
-	tmp = (page->index << PAGE_SHIFT) + from;
+	tmp = (folio->index << PAGE_SHIFT) + from;
 	bidx = tmp / bsize;
 	boff = tmp % bsize;
 	if (boff) {
@@ -804,11 +803,11 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 		from += tmp;
 		bidx++;
 	}
-	SetPageUptodate(page);
+	folio_mark_uptodate(folio);
 
 done:
 	affs_brelse(bh);
-	tmp = (page->index << PAGE_SHIFT) + from;
+	tmp = (folio->index << PAGE_SHIFT) + from;
 	if (tmp > inode->i_size)
 		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
 
@@ -819,8 +818,8 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 	}
 
 err_first_bh:
-	unlock_page(page);
-	put_page(page);
+	folio_unlock(folio);
+	folio_put(folio);
 
 	return written;
 
-- 
2.39.2

[PATCH 4/7] migrate: Use folio_set_bh() instead of set_bh_page()

[Matthew Wilcox (Oracle)]

This function was converted before folio_set_bh() existed.  Catch
up to the new API.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index af8557d78549..1363053894ce 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -773,7 +773,7 @@ static int __buffer_migrate_folio(struct address_space *mapping,
 
 	bh = head;
 	do {
-		set_bh_page(bh, &dst->page, bh_offset(bh));
+		folio_set_bh(bh, dst, bh_offset(bh));
 		bh = bh->b_this_page;
 	} while (bh != head);
 
-- 
2.39.2

[PATCH 5/7] ntfs3: Convert ntfs_get_block_vbo() to use a folio

[Matthew Wilcox (Oracle)]

Remove a user of set_bh_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/ntfs3/inode.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index dc7e7ab701c6..8ae572aacc69 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -554,7 +554,7 @@ static noinline int ntfs_get_block_vbo(struct inode *inode, u64 vbo,
 	struct super_block *sb = inode->i_sb;
 	struct ntfs_sb_info *sbi = sb->s_fs_info;
 	struct ntfs_inode *ni = ntfs_i(inode);
-	struct page *page = bh->b_page;
+	struct folio *folio = bh->b_folio;
 	u8 cluster_bits = sbi->cluster_bits;
 	u32 block_size = sb->s_blocksize;
 	u64 bytes, lbo, valid;
@@ -569,7 +569,7 @@ static noinline int ntfs_get_block_vbo(struct inode *inode, u64 vbo,
 
 	if (is_resident(ni)) {
 		ni_lock(ni);
-		err = attr_data_read_resident(ni, page);
+		err = attr_data_read_resident(ni, &folio->page);
 		ni_unlock(ni);
 
 		if (!err)
@@ -642,17 +642,17 @@ static noinline int ntfs_get_block_vbo(struct inode *inode, u64 vbo,
 		 */
 		bytes = block_size;
 
-		if (page) {
+		if (folio) {
 			u32 voff = valid - vbo;
 
 			bh->b_size = block_size;
 			off = vbo & (PAGE_SIZE - 1);
-			set_bh_page(bh, page, off);
+			folio_set_bh(bh, folio, off);
 
 			err = bh_read(bh, 0);
 			if (err < 0)
 				goto out;
-			zero_user_segment(page, off + voff, off + block_size);
+			folio_zero_segment(folio, off + voff, off + block_size);
 		}
 	}
 
-- 
2.39.2

[PATCH 6/7] jbd2: Use a folio in jbd2_journal_write_metadata_buffer()

[Matthew Wilcox (Oracle)]

The primary goal here is removing the use of set_bh_page().
Take the opportunity to switch from kmap_atomic() to kmap_local().
This simplifies the function as the offset is already added to
the pointer.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/jbd2/journal.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index fbce16fedaa4..1b5a45ab62b0 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -341,7 +341,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	int do_escape = 0;
 	char *mapped_data;
 	struct buffer_head *new_bh;
-	struct page *new_page;
+	struct folio *new_folio;
 	unsigned int new_offset;
 	struct buffer_head *bh_in = jh2bh(jh_in);
 	journal_t *journal = transaction->t_journal;
@@ -370,14 +370,14 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	 */
 	if (jh_in->b_frozen_data) {
 		done_copy_out = 1;
-		new_page = virt_to_page(jh_in->b_frozen_data);
-		new_offset = offset_in_page(jh_in->b_frozen_data);
+		new_folio = virt_to_folio(jh_in->b_frozen_data);
+		new_offset = offset_in_folio(new_folio, jh_in->b_frozen_data);
 	} else {
-		new_page = jh2bh(jh_in)->b_page;
-		new_offset = offset_in_page(jh2bh(jh_in)->b_data);
+		new_folio = jh2bh(jh_in)->b_folio;
+		new_offset = offset_in_folio(new_folio, jh2bh(jh_in)->b_data);
 	}
 
-	mapped_data = kmap_atomic(new_page);
+	mapped_data = kmap_local_folio(new_folio, new_offset);
 	/*
 	 * Fire data frozen trigger if data already wasn't frozen.  Do this
 	 * before checking for escaping, as the trigger may modify the magic
@@ -385,18 +385,17 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	 * data in the buffer.
 	 */
 	if (!done_copy_out)
-		jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
+		jbd2_buffer_frozen_trigger(jh_in, mapped_data,
 					   jh_in->b_triggers);
 
 	/*
 	 * Check for escaping
 	 */
-	if (*((__be32 *)(mapped_data + new_offset)) ==
-				cpu_to_be32(JBD2_MAGIC_NUMBER)) {
+	if (*((__be32 *)mapped_data) == cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 		need_copy_out = 1;
 		do_escape = 1;
 	}
-	kunmap_atomic(mapped_data);
+	kunmap_local(mapped_data);
 
 	/*
 	 * Do we need to do a data copy?
@@ -417,12 +416,10 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 		}
 
 		jh_in->b_frozen_data = tmp;
-		mapped_data = kmap_atomic(new_page);
-		memcpy(tmp, mapped_data + new_offset, bh_in->b_size);
-		kunmap_atomic(mapped_data);
+		memcpy_from_folio(tmp, new_folio, new_offset, bh_in->b_size);
 
-		new_page = virt_to_page(tmp);
-		new_offset = offset_in_page(tmp);
+		new_folio = virt_to_folio(tmp);
+		new_offset = offset_in_folio(new_folio, tmp);
 		done_copy_out = 1;
 
 		/*
@@ -438,12 +435,12 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	 * copying, we can finally do so.
 	 */
 	if (do_escape) {
-		mapped_data = kmap_atomic(new_page);
-		*((unsigned int *)(mapped_data + new_offset)) = 0;
-		kunmap_atomic(mapped_data);
+		mapped_data = kmap_local_folio(new_folio, new_offset);
+		*((unsigned int *)mapped_data) = 0;
+		kunmap_local(mapped_data);
 	}
 
-	set_bh_page(new_bh, new_page, new_offset);
+	folio_set_bh(new_bh, new_folio, new_offset);
 	new_bh->b_size = bh_in->b_size;
 	new_bh->b_bdev = journal->j_dev;
 	new_bh->b_blocknr = blocknr;
-- 
2.39.2

[PATCH 7/7] buffer: Remove set_bh_page()

[Matthew Wilcox (Oracle)]

With all users converted to folio_set_bh(), remove this function.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/buffer.c                 | 15 ---------------
 include/linux/buffer_head.h |  2 --
 2 files changed, 17 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 587e4d4af9de..f0563ebae75f 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1539,21 +1539,6 @@ void invalidate_bh_lrus_cpu(void)
 	bh_lru_unlock();
 }
 
-void set_bh_page(struct buffer_head *bh,
-		struct page *page, unsigned long offset)
-{
-	bh->b_page = page;
-	BUG_ON(offset >= PAGE_SIZE);
-	if (PageHighMem(page))
-		/*
-		 * This catches illegal uses and preserves the offset:
-		 */
-		bh->b_data = (char *)(0 + offset);
-	else
-		bh->b_data = page_address(page) + offset;
-}
-EXPORT_SYMBOL(set_bh_page);
-
 void folio_set_bh(struct buffer_head *bh, struct folio *folio,
 		  unsigned long offset)
 {
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index a7377877ff4e..06566aee94ca 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -194,8 +194,6 @@ void buffer_check_dirty_writeback(struct folio *folio,
 void mark_buffer_dirty(struct buffer_head *bh);
 void mark_buffer_write_io_error(struct buffer_head *bh);
 void touch_buffer(struct buffer_head *bh);
-void set_bh_page(struct buffer_head *bh,
-		struct page *page, unsigned long offset);
 void folio_set_bh(struct buffer_head *bh, struct folio *folio,
 		  unsigned long offset);
 bool try_to_free_buffers(struct folio *);
-- 
2.39.2

Re: [PATCH 3/7] affs: Convert data read and write to use folios

[Pankaj Raghav]

On 2023-07-13 05:55, Matthew Wilcox (Oracle) wrote:
> We still need to convert to/from folios in write_begin & write_end
> to fit the API, but this removes a lot of calls to old page-based
> functions, removing many hidden calls to compound_head().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Looks good to me except one minor nit!

Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>

> @@ -624,25 +623,23 @@ affs_extent_file_ofs(struct inode *inode, u32 newsize)
>  	return PTR_ERR(bh);
>  }
>  
> -static int
> -affs_read_folio_ofs(struct file *file, struct folio *folio)
> +static int affs_read_folio_ofs(struct file *file, struct folio *folio)
>  {
> -	struct page *page = &folio->page;
> -	struct inode *inode = page->mapping->host;
> -	u32 to;
> +	struct inode *inode = folio->mapping->host;
> +	size_t to;
>  	int err;
>  
> -	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
> -	to = PAGE_SIZE;
> -	if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
> -		to = inode->i_size & ~PAGE_MASK;
> -		memset(page_address(page) + to, 0, PAGE_SIZE - to);
> +	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, folio->index);
> +	to = folio_size(folio);
> +	if (folio_pos(folio) + to > inode->i_size) {
> +		to = inode->i_size - folio_pos(folio);
> +		folio_zero_segment(folio, to, folio_size(folio));

This change makes the code more readable!

>  	}
>  
> -	err = affs_do_readpage_ofs(page, to, 0);
> +	err = affs_do_read_folio_ofs(folio, to, 0);
>  	if (!err)
> @@ -688,6 +686,7 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
>  				loff_t pos, unsigned len, unsigned copied,
>  				struct page *page, void *fsdata)
>  {
> +	struct folio *folio = page_folio(page);
>  	struct inode *inode = mapping->host;
>  	struct super_block *sb = inode->i_sb;
>  	struct buffer_head *bh, *prev_bh;
> @@ -701,18 +700,18 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
>  	to = from + len;
>  	/*
>  	 * XXX: not sure if this can handle short copies (len < copied), but
> -	 * we don't have to, because the page should always be uptodate here,
> +	 * we don't have to, because the folio should always be uptodate here,
>  	 * due to write_begin.
>  	 */
>  
>  	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
>  		 pos + len);
>  	bsize = AFFS_SB(sb)->s_data_blksize;
> -	data = page_address(page);
> +	data = folio_address(folio);
>  
>  	bh = NULL;
>  	written = 0;
> -	tmp = (page->index << PAGE_SHIFT) + from;
> +	tmp = (folio->index << PAGE_SHIFT) + from;

Can this be made to:

tmp = folio_pos(folio) + from;

Similar to what is being done in affs_do_read_folio_ofs()

>  	bidx = tmp / bsize;
>  	boff = tmp % bsize;
>  	if (boff) {
> @@ -804,11 +803,11 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
>  		from += tmp;
>  		bidx++;
>  	}
> -	SetPageUptodate(page);
> +	folio_mark_uptodate(folio);
>  
>  done:
>  	affs_brelse(bh);
> -	tmp = (page->index << PAGE_SHIFT) + from;
> +	tmp = (folio->index << PAGE_SHIFT) + from;

Same as the previous comment.

>  	if (tmp > inode->i_size)
>  		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
>  
> @@ -819,8 +818,8 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
>  	}
>  
>  err_first_bh:
> -	unlock_page(page);
> -	put_page(page);
> +	folio_unlock(folio);
> +	folio_put(folio);
>  
>  	return written;
>  

Re: [PATCH 2/7] affs: Convert affs_symlink_read_folio() to use the folio

[David Sterba]

On Thu, Jul 13, 2023 at 04:55:07AM +0100, Matthew Wilcox (Oracle) wrote:
> Remove use of the old page APIs.  That includes use of setting PageError
> on error; simply not setting the uptodate flag is sufficient.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Acked-by: David Sterba <dsterba@suse.com>

Re: [PATCH 3/7] affs: Convert data read and write to use folios

[David Sterba]

On Thu, Jul 13, 2023 at 04:55:08AM +0100, Matthew Wilcox (Oracle) wrote:
> We still need to convert to/from folios in write_begin & write_end
> to fit the API, but this removes a lot of calls to old page-based
> functions, removing many hidden calls to compound_head().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Acked-by: David Sterba <dsterba@suse.com>

Re: [PATCH 1/7] highmem: Add memcpy_to_folio() and memcpy_from_folio()

[Andreas Grünbacher]

Am Do., 13. Juli 2023 um 06:04 Uhr schrieb Matthew Wilcox (Oracle)
<willy@infradead.org>:
> These are the folio equivalent of memcpy_to_page() and memcpy_from_page().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  include/linux/highmem.h | 44 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index 68da30625a6c..0280f57d4744 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -439,6 +439,50 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len)
>         kunmap_local(addr);
>  }
>
> +static inline void memcpy_from_folio(char *to, struct folio *folio,
> +               size_t offset, size_t len)
> +{
> +       VM_BUG_ON(offset + len > folio_size(folio));
> +
> +       do {
> +               char *from = kmap_local_folio(folio, offset);
> +               size_t chunk = len;
> +
> +               if (folio_test_highmem(folio) &&
> +                   (chunk > (PAGE_SIZE - offset_in_page(offset))))
> +                       chunk = PAGE_SIZE - offset_in_page(offset);
> +               memcpy(to, from, len);

We want memcpy(to, from, chunk) here.

> +               kunmap_local(from);
> +
> +               from += chunk;
> +               offset += chunk;
> +               len -= chunk;
> +       } while (len > 0);
> +}
> +
> +static inline void memcpy_to_folio(struct folio *folio, size_t offset,
> +               const char *from, size_t len)
> +{
> +       VM_BUG_ON(offset + len > folio_size(folio));
> +
> +       do {
> +               char *to = kmap_local_folio(folio, offset);
> +               size_t chunk = len;
> +
> +               if (folio_test_highmem(folio) &&
> +                   (chunk > (PAGE_SIZE - offset_in_page(offset))))
> +                       chunk = PAGE_SIZE - offset_in_page(offset);
> +               memcpy(to, from, len);

And also here.

> +               kunmap_local(to);
> +
> +               from += chunk;
> +               offset += chunk;
> +               len -= chunk;
> +       } while (len > 0);
> +
> +       flush_dcache_folio(folio);
> +}
> +
>  /**
>   * memcpy_from_file_folio - Copy some bytes from a file folio.
>   * @to: The destination buffer.
> --
> 2.39.2
>

Thanks,
Andreas

Re: [PATCH 6/7] jbd2: Use a folio in jbd2_journal_write_metadata_buffer()

[Jan Kara]

On Thu 13-07-23 04:55:11, Matthew Wilcox (Oracle) wrote:
> The primary goal here is removing the use of set_bh_page().
> Take the opportunity to switch from kmap_atomic() to kmap_local().
> This simplifies the function as the offset is already added to
> the pointer.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

							Honza

> ---
>  fs/jbd2/journal.c | 35 ++++++++++++++++-------------------
>  1 file changed, 16 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index fbce16fedaa4..1b5a45ab62b0 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -341,7 +341,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
>  	int do_escape = 0;
>  	char *mapped_data;
>  	struct buffer_head *new_bh;
> -	struct page *new_page;
> +	struct folio *new_folio;
>  	unsigned int new_offset;
>  	struct buffer_head *bh_in = jh2bh(jh_in);
>  	journal_t *journal = transaction->t_journal;
> @@ -370,14 +370,14 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
>  	 */
>  	if (jh_in->b_frozen_data) {
>  		done_copy_out = 1;
> -		new_page = virt_to_page(jh_in->b_frozen_data);
> -		new_offset = offset_in_page(jh_in->b_frozen_data);
> +		new_folio = virt_to_folio(jh_in->b_frozen_data);
> +		new_offset = offset_in_folio(new_folio, jh_in->b_frozen_data);
>  	} else {
> -		new_page = jh2bh(jh_in)->b_page;
> -		new_offset = offset_in_page(jh2bh(jh_in)->b_data);
> +		new_folio = jh2bh(jh_in)->b_folio;
> +		new_offset = offset_in_folio(new_folio, jh2bh(jh_in)->b_data);
>  	}
>  
> -	mapped_data = kmap_atomic(new_page);
> +	mapped_data = kmap_local_folio(new_folio, new_offset);
>  	/*
>  	 * Fire data frozen trigger if data already wasn't frozen.  Do this
>  	 * before checking for escaping, as the trigger may modify the magic
> @@ -385,18 +385,17 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
>  	 * data in the buffer.
>  	 */
>  	if (!done_copy_out)
> -		jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
> +		jbd2_buffer_frozen_trigger(jh_in, mapped_data,
>  					   jh_in->b_triggers);
>  
>  	/*
>  	 * Check for escaping
>  	 */
> -	if (*((__be32 *)(mapped_data + new_offset)) ==
> -				cpu_to_be32(JBD2_MAGIC_NUMBER)) {
> +	if (*((__be32 *)mapped_data) == cpu_to_be32(JBD2_MAGIC_NUMBER)) {
>  		need_copy_out = 1;
>  		do_escape = 1;
>  	}
> -	kunmap_atomic(mapped_data);
> +	kunmap_local(mapped_data);
>  
>  	/*
>  	 * Do we need to do a data copy?
> @@ -417,12 +416,10 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
>  		}
>  
>  		jh_in->b_frozen_data = tmp;
> -		mapped_data = kmap_atomic(new_page);
> -		memcpy(tmp, mapped_data + new_offset, bh_in->b_size);
> -		kunmap_atomic(mapped_data);
> +		memcpy_from_folio(tmp, new_folio, new_offset, bh_in->b_size);
>  
> -		new_page = virt_to_page(tmp);
> -		new_offset = offset_in_page(tmp);
> +		new_folio = virt_to_folio(tmp);
> +		new_offset = offset_in_folio(new_folio, tmp);
>  		done_copy_out = 1;
>  
>  		/*
> @@ -438,12 +435,12 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
>  	 * copying, we can finally do so.
>  	 */
>  	if (do_escape) {
> -		mapped_data = kmap_atomic(new_page);
> -		*((unsigned int *)(mapped_data + new_offset)) = 0;
> -		kunmap_atomic(mapped_data);
> +		mapped_data = kmap_local_folio(new_folio, new_offset);
> +		*((unsigned int *)mapped_data) = 0;
> +		kunmap_local(mapped_data);
>  	}
>  
> -	set_bh_page(new_bh, new_page, new_offset);
> +	folio_set_bh(new_bh, new_folio, new_offset);
>  	new_bh->b_size = bh_in->b_size;
>  	new_bh->b_bdev = journal->j_dev;
>  	new_bh->b_blocknr = blocknr;
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH 4/7] migrate: Use folio_set_bh() instead of set_bh_page()

[Jan Kara]

On Thu 13-07-23 04:55:09, Matthew Wilcox (Oracle) wrote:
> This function was converted before folio_set_bh() existed.  Catch
> up to the new API.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  mm/migrate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index af8557d78549..1363053894ce 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -773,7 +773,7 @@ static int __buffer_migrate_folio(struct address_space *mapping,
>  
>  	bh = head;
>  	do {
> -		set_bh_page(bh, &dst->page, bh_offset(bh));
> +		folio_set_bh(bh, dst, bh_offset(bh));
>  		bh = bh->b_this_page;
>  	} while (bh != head);
>  
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH 7/7] buffer: Remove set_bh_page()

[Jan Kara]

On Thu 13-07-23 04:55:12, Matthew Wilcox (Oracle) wrote:
> With all users converted to folio_set_bh(), remove this function.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Sure. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/buffer.c                 | 15 ---------------
>  include/linux/buffer_head.h |  2 --
>  2 files changed, 17 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 587e4d4af9de..f0563ebae75f 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1539,21 +1539,6 @@ void invalidate_bh_lrus_cpu(void)
>  	bh_lru_unlock();
>  }
>  
> -void set_bh_page(struct buffer_head *bh,
> -		struct page *page, unsigned long offset)
> -{
> -	bh->b_page = page;
> -	BUG_ON(offset >= PAGE_SIZE);
> -	if (PageHighMem(page))
> -		/*
> -		 * This catches illegal uses and preserves the offset:
> -		 */
> -		bh->b_data = (char *)(0 + offset);
> -	else
> -		bh->b_data = page_address(page) + offset;
> -}
> -EXPORT_SYMBOL(set_bh_page);
> -
>  void folio_set_bh(struct buffer_head *bh, struct folio *folio,
>  		  unsigned long offset)
>  {
> diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
> index a7377877ff4e..06566aee94ca 100644
> --- a/include/linux/buffer_head.h
> +++ b/include/linux/buffer_head.h
> @@ -194,8 +194,6 @@ void buffer_check_dirty_writeback(struct folio *folio,
>  void mark_buffer_dirty(struct buffer_head *bh);
>  void mark_buffer_write_io_error(struct buffer_head *bh);
>  void touch_buffer(struct buffer_head *bh);
> -void set_bh_page(struct buffer_head *bh,
> -		struct page *page, unsigned long offset);
>  void folio_set_bh(struct buffer_head *bh, struct folio *folio,
>  		  unsigned long offset);
>  bool try_to_free_buffers(struct folio *);
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR