From 0e267c44c3a402d35111d1935be1167240b5b79f Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Tue, 2 Jul 2013 10:38:02 -0400 Subject: [PATCH] Btrfs: wait ordered range before doing direct io My recent truncate patch uncovered this bug, but I can reproduce it without the truncate patch. If you mount with -o compress-force, do a direct write to some area, do a buffered write to some other area, and then do a direct read you will get the wrong data for where you did the buffered write. This is because the generic direct io helpers only call filemap_write_and_wait once, and for compression we need it twice. So to be safe add the btrfs_wait_ordered_range to the start of the direct io function to make sure any compressed writes have truly been written. This patch makes xfstests 130 pass when you mount with -o compress-force=lzo. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/inode.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0a43d42268f7..55dda871437f 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7270,8 +7270,16 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, atomic_inc(&inode->i_dio_count); smp_mb__after_atomic_inc(); + /* + * The generic stuff only does filemap_write_and_wait_range, which isn't + * enough if we've written compressed pages to this area, so we need to + * call btrfs_wait_ordered_range to make absolutely sure that any + * outstanding dirty pages are on disk. + */ + count = iov_length(iov, nr_segs); + btrfs_wait_ordered_range(inode, offset, count); + if (rw & WRITE) { - count = iov_length(iov, nr_segs); /* * If the write DIO is beyond the EOF, we need update * the isize, but it is protected by i_mutex. So we can