[PATCH] md: fix locking problem in r5/r6

bitmap_unplug actually writes data (bits) to storage, so we shouldn't be
holding a spinlock...

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index eae5a35..17d88d9 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -1784,7 +1784,9 @@
 
 		if (conf->seq_flush - conf->seq_write > 0) {
 			int seq = conf->seq_flush;
+			spin_unlock_irq(&conf->device_lock);
 			bitmap_unplug(mddev->bitmap);
+			spin_lock_irq(&conf->device_lock);
 			conf->seq_write = seq;
 			activate_bit_delay(conf);
 		}