ext4: Automatically allocate delay allocated blocks on rename

ext4: Automatically allocate delay allocated blocks on rename

(cherry picked from commit 8750c6d5fcbd3342b3d908d157f81d345c5325a7)

When renaming a file such that a link to another inode is overwritten,
force any delay allocated blocks that to be allocated so that if the
filesystem is mounted with data=ordered, the data blocks will be
pushed out to disk along with the journal commit.  Many application
programs expect this, so we do this to avoid zero length files if the
system crashes unexpectedly.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>