[PATCH] Reduce sched latency in shrink_dcache_sb()

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: NDenis Lunev <den@sw.ru>
Signed-off-by: NPavel Emelianov <xemul@sw.ru>
Signed-off-by: NKirill Korotaev <dev@openvz.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

fs/dcache.c

@@ -489,6 +489,7 @@ void shrink_dcache_sb(struct super_block * sb)
 			continue;
 		}
 		prune_one_dentry(dentry);
+		cond_resched_lock(&dcache_lock);
 		goto repeat;
 	}
 	spin_unlock(&dcache_lock);