Save ~650 bytes here.

add/remove: 4/0 grow/shrink: 0/7 up/down: 430/-1088 (-658)
function                                     old     new   delta
__copy_fs_struct                               -     202    +202
__put_fs_struct                                -     112    +112
__exit_fs                                      -      58     +58
__exit_files                                   -      58     +58
exit_files                                    58       2     -56
put_fs_struct                                112       5    -107
exit_fs                                      161       2    -159
sys_unshare                                  774     590    -184
copy_process                                4031    3840    -191
do_exit                                     1791    1597    -194
copy_fs_struct                               202       5    -197

No difference in lmbench lat_proc tests on 2-way Opteron 246.
Smaaaal degradation on UP P4 (within errors).

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>