generic: fsync after file rename

generic: fsync after file rename

Test that if we rename a file, without changing its parent
directory, create a new file that has the old name of the file we
renamed, doing an fsync against the file we renamed works correctly
and after a power failure both files exists.

This is motivated by an issue found in btrfs, introduced in the
linux kernel 4.8-rc2, that caused lockdep to report a deadlock
scenario. The btrfs issue is fixed by the patch titled:

  "Btrfs: fix lockdep warning on deadlock against an inode's log mutex"

Tested against ext3/4, xfs, f2fs and reiserfs as well.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>