ext3: add support for .read_iter and .write_iter

ext3 uses the generic .read_iter and .write_iter functions.

ext3_direct_IO() is refactored in to helpers which are called by the
.direct_IO{,bvec}() methods which call __blockdev_direct_IO{,_bvec}().

Signed-off-by: Zach Brown <zach.brown@oracle.com>
(cherry picked from commit 7033fac02ea52fe425545c70f260abaf667f7093)
2 files changed