Commit e78faefb authored by Zhihao Cheng's avatar Zhihao Cheng Committed by Liu Shixin
Browse files

ext4: Fix WARNON in generic write begin path for iomap mode 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAHY3K



--------------------------------

Since commit 9aac777aaf94 ("filemap: Convert generic_perform_write() to
support large folios"), write_begin() could get a range of data cross two
pages, which triggers the WARNON in ext4_iomap_write_begin():
 WARN_ON_ONCE(pos + len > folio_pos(folio) + folio_size(folio))

Since generic_perform_write() will cut the copy length within a
page, fix the problem by cutting the data length within a page
in ext4_iomap_write_begin(),

Fixes: 9aac777aaf94 ("filemap: Convert generic_perform_write() to support large folios")
Signed-off-by: default avatarZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent df42d7a5

fs/ext4/inode.c

+5 −4
Original line number Diff line number Diff line
@@ -3976,18 +3976,19 @@ static int ext4_iomap_write_begin(struct file *file, 
	*fsdata = delalloc ? (void *)0 : (void *)FALL_BACK_TO_NONDELALLOC;



retry:

	iter.pos = pos;

	iter.len = len;



	folio = iomap_get_folio(&iter, pos, len);

	if (IS_ERR(folio))

		return PTR_ERR(folio);



	WARN_ON_ONCE(pos + len > folio_pos(folio) + folio_size(folio));

	if (pos + len > folio_pos(folio) + folio_size(folio))

		len = folio_pos(folio) + folio_size(folio) - pos;



	if (iomap_is_fully_dirty(folio, offset_in_folio(folio, pos), len))

		goto out;



	iter.pos = pos;

	iter.len = len;



	do {

		int length;