ext4 dio RWF_NOWAIT change

[Murphy Zhou <jencce.kernel@xxxxxxxxx>]

Hi,

Kernel commit 378f32bab3714f04c4e0c3aee4129f6703805550
Author: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
Date:   Tue Nov 5 23:02:39 2019 +1100

    ext4: introduce direct I/O write using iomap infrastructure


Changed the logic of dio+RWF_NOWAIT

from:

-       if (!inode_trylock(inode)) {
-               if (iocb->ki_flags & IOCB_NOWAIT)
-                       return -EAGAIN;
-               inode_lock(inode);
-       }


to:

+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (!inode_trylock(inode))
+                       return -EAGAIN;
+       } else {
+               inode_lock(inode);
+       }


fstests generic/471 expecet EAGAIN on this situation, so it started to
fail since than.

The current logic is similar with other filesystems, but only ext4 fails
on geneirc/471.

Any thoughts how to fix this?

Thanks,
Murphy