3.0-stable review patch. If anyone has any objections, please let us know.
------------------
From: Theodore Ts'o <ty...@mit.edu>
commit 9dd75f1f1a02d656a11a7b9b9e6c2759b9c1e946 upstream.
Bug discovered by Jan Kara:
Finally, commit 1449032be17abb69116dbc393f67ceb8bd034f92 returned back
the old IO submission code but apparently it forgot to return the old
handling of uninitialized buffers so we unconditionnaly call
block_write_full_page() without specifying end_io function. So AFAICS
we never convert unwritten extents to written in some cases. For
example when I mount the fs as: mount -t ext4 -o
nomblk_io_submit,dioread_nolock /dev/ubdb /mnt and do
int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0600);
char buf[1024];
memset(buf, 'a', sizeof(buf));
fallocate(fd, 0, 0, 16384);
write(fd, buf, sizeof(buf));
I get a file full of zeros (after remounting the filesystem so that
pagecache is dropped) instead of seeing the first KB contain 'a's.
Signed-off-by: "Theodore Ts'o" <ty...@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
fs/ext4/inode.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2156,7 +2156,12 @@ static int mpage_da_submit_io(struct mpa
else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
err = ext4_bio_write_page(&io_submit, page,
len, mpd->wbc);
- else
+ else if (buffer_uninit(page_bufs)) {
+ ext4_set_bh_endio(page_bufs, inode);
+ err = block_write_full_page_endio(page,
+ noalloc_get_block_write,
+ mpd->wbc, ext4_end_io_buffer_write);
+ } else
err = block_write_full_page(page,
noalloc_get_block_write, mpd->wbc);
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