This patch reduces scheduling latency in shrink_dcache_sb()
noticed during remounting of big partitions with many cached dentries.
The same latency fix was applied to select_parent() long ago.

Signed-Off-By: Denis Lunev <den@sw.ru>
Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@openvz.org>

Thanks,
Kirill