This is a note to let you know that I've just added the patch titled ext4: fix data corruption in data=journal mode to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-fix-data-corruption-in-data-journal-mode.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 3b136499e906460919f0d21a49db1aaccf0ae963 Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@xxxxxxx> Date: Fri, 27 Jan 2017 14:35:38 -0500 Subject: ext4: fix data corruption in data=journal mode From: Jan Kara <jack@xxxxxxx> commit 3b136499e906460919f0d21a49db1aaccf0ae963 upstream. ext4_journalled_write_end() did not propely handle all the cases when generic_perform_write() did not copy all the data into the target page and could mark buffers with uninitialized contents as uptodate and dirty leading to possible data corruption (which would be quickly fixed by generic_perform_write() retrying the write but still). Fix the problem by carefully handling the case when the page that is written to is not uptodate. Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inode.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1220,7 +1220,9 @@ errout: * set the buffer to be dirty, since in data=journalled mode we need * to call ext4_handle_dirty_metadata() instead. */ -static void zero_new_buffers(struct page *page, unsigned from, unsigned to) +static void ext4_journalled_zero_new_buffers(handle_t *handle, + struct page *page, + unsigned from, unsigned to) { unsigned int block_start = 0, block_end; struct buffer_head *head, *bh; @@ -1237,7 +1239,7 @@ static void zero_new_buffers(struct page size = min(to, block_end) - start; zero_user(page, start, size); - set_buffer_uptodate(bh); + write_end_fn(handle, bh); } clear_buffer_new(bh); } @@ -1269,15 +1271,16 @@ static int ext4_journalled_write_end(str if (ext4_has_inline_data(inode)) copied = ext4_write_inline_data_end(inode, pos, len, copied, page); - else { - if (copied < len) { - if (!PageUptodate(page)) - copied = 0; - zero_new_buffers(page, from+copied, to); - } - + else if (unlikely(copied < len) && !PageUptodate(page)) { + copied = 0; + ext4_journalled_zero_new_buffers(handle, page, from, to); + } else { + if (unlikely(copied < len)) + ext4_journalled_zero_new_buffers(handle, page, + from + copied, to); ret = ext4_walk_page_buffers(handle, page_buffers(page), from, - to, &partial, write_end_fn); + from + copied, &partial, + write_end_fn); if (!partial) SetPageUptodate(page); } Patches currently in stable-queue which might be from jack@xxxxxxx are queue-4.4/ext4-fix-data-corruption-in-data-journal-mode.patch queue-4.4/ext4-trim-allocation-requests-to-group-size.patch