From: Jan Kara <jack@suse.cz>
Date: Thu, 1 Dec 2016 16:46:40 +0000 (-0500)
Subject: ext4: warn when page is dirtied without buffers
X-Git-Tag: v4.10-rc1~130^2~21
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=6dcc693bc57f;p=linux.git

ext4: warn when page is dirtied without buffers

Warn when a page is dirtied without buffers (as that will likely lead to
a crash in ext4_writepages()) or when it gets newly dirtied without the
page being locked (as there is nothing that prevents buffers to get
stripped just before calling set_page_dirty() under memory pressure).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 861f848159e8..7d95b6174980 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3714,6 +3714,13 @@ static int ext4_journalled_set_page_dirty(struct page *page)
 	return __set_page_dirty_nobuffers(page);
 }
 
+static int ext4_set_page_dirty(struct page *page)
+{
+	WARN_ON_ONCE(!PageLocked(page) && !PageDirty(page));
+	WARN_ON_ONCE(!page_has_buffers(page));
+	return __set_page_dirty_buffers(page);
+}
+
 static const struct address_space_operations ext4_aops = {
 	.readpage		= ext4_readpage,
 	.readpages		= ext4_readpages,
@@ -3721,6 +3728,7 @@ static const struct address_space_operations ext4_aops = {
 	.writepages		= ext4_writepages,
 	.write_begin		= ext4_write_begin,
 	.write_end		= ext4_write_end,
+	.set_page_dirty		= ext4_set_page_dirty,
 	.bmap			= ext4_bmap,
 	.invalidatepage		= ext4_invalidatepage,
 	.releasepage		= ext4_releasepage,
@@ -3753,6 +3761,7 @@ static const struct address_space_operations ext4_da_aops = {
 	.writepages		= ext4_writepages,
 	.write_begin		= ext4_da_write_begin,
 	.write_end		= ext4_da_write_end,
+	.set_page_dirty		= ext4_set_page_dirty,
 	.bmap			= ext4_bmap,
 	.invalidatepage		= ext4_da_invalidatepage,
 	.releasepage		= ext4_releasepage,