generic: test file fsync after rename operation

generic: test file fsync after rename operation

Test that if we have a file F1 with two links, one in a directory A and
the other in directory B, if we remove the link in directory B, move some
other file F2 from directory B into directory C, fsync inode F1, power
fail and remount the filesystem, file F2 exists and is located only in
directory C.

This is motivated by a bug found in btrfs, which is fixed by the patch
(for the linux kernel) titled:

   "Btrfs: fix file loss on log replay after renaming a file and fsync"

Tested against ext3, ext4, xfs, f2fs and reiserfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>