[patch 097/104] ext4: Mark the buffer_heads as dirty and uptodateafter prepare_write

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>

(cherry picked from commit ed9b3e3379731e9f9d2f73f3d7fd9e7d2ce3df4a)

We need to make sure we mark the buffer_heads as dirty and uptodate
so that block_write_full_page write them correctly.

This fixes mmap corruptions that can occur in low memory situations.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/ext4/inode.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2242,6 +2242,8 @@ static int ext4_da_writepage(struct page
 			unlock_page(page);
 			return 0;
 		}
+		/* now mark the buffer_heads as dirty and uptodate */
+		block_commit_write(page, 0, PAGE_CACHE_SIZE);
 	}
 
 	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))

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