[PATCH] percpu_counter: fix irq restore in __percpu_counter_add

[Christoph Hellwig <hch@infradead.org>]

The current version of "percpu_counter: make APIs irq safe" in the blk-mq
tree doesn't properly restore irqs, thus causing the boot of the blk-multique
tree to fail with various irqs_disabled() BUGs and related issues.
     
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 1ae43a7..7473ee3 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -82,7 +82,7 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
 		unsigned long flags;
 		raw_spin_lock_irqsave(&fbc->lock, flags);
 		fbc->count += count;
-		raw_spin_unlock(&fbc->lock);
+		raw_spin_unlock_irqrestore(&fbc->lock, flags);
 		__this_cpu_write(*fbc->counters, 0);
 	} else {
 		__this_cpu_write(*fbc->counters, count);