---
 drivers/md/persistent-data/dm-transaction-manager.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

Index: linux-3.0/drivers/md/persistent-data/dm-transaction-manager.c
===================================================================
--- linux-3.0.orig/drivers/md/persistent-data/dm-transaction-manager.c
+++ linux-3.0/drivers/md/persistent-data/dm-transaction-manager.c
@@ -35,6 +35,7 @@ struct dm_transaction_manager {
 	struct dm_block_manager *bm;
 	struct dm_space_map *sm;
 
+	spinlock_t lock;
 	struct hlist_head buckets[HASH_SIZE];
 };
 
@@ -45,12 +46,18 @@ static int is_shadow(struct dm_transacti
 	unsigned bucket = dm_hash_block(b, HASH_MASK);
 	struct shadow_info *si;
 	struct hlist_node *n;
+	unsigned long flags;
+	int r = 0;
+
+	spin_lock_irqsave(&tm->lock, flags);
 
 	hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
 		if (si->where == b)
-			return 1;
+			r = 1;
 
-	return 0;
+	spin_unlock_irqrestore(&tm->lock, flags);
+
+	return r;
 }
 
 /*
@@ -61,12 +68,16 @@ static void insert_shadow(struct dm_tran
 {
 	unsigned bucket;
 	struct shadow_info *si;
+	unsigned long flags;
 
 	si = kmalloc(sizeof(*si), GFP_NOIO);
 	if (si) {
 		si->where = b;
 		bucket = dm_hash_block(b, HASH_MASK);
+
+		spin_lock_irqsave(&tm->lock, flags);
 		hlist_add_head(&si->hlist, tm->buckets + bucket);
+		spin_unlock_irqrestore(&tm->lock, flags);
 	}
 }
 
@@ -75,8 +86,10 @@ static void wipe_shadow_table(struct dm_
 	struct shadow_info *si;
 	struct hlist_node *n, *tmp;
 	struct hlist_head *bucket;
+	unsigned long flags;
 	int i;
 
+	spin_lock_irqsave(&tm->lock, flags);
 	for (i = 0; i < HASH_SIZE; i++) {
 		bucket = tm->buckets + i;
 		hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
@@ -84,6 +97,7 @@ static void wipe_shadow_table(struct dm_
 
 		INIT_HLIST_HEAD(bucket);
 	}
+	spin_unlock_irqrestore(&tm->lock, flags);
 }
 
 /*----------------------------------------------------------------*/
@@ -103,6 +117,7 @@ static struct dm_transaction_manager *dm
 	tm->bm = bm;
 	tm->sm = sm;
 
+	spin_lock_init(&tm->lock);
 	for (i = 0; i < HASH_SIZE; i++)
 		INIT_HLIST_HEAD(tm->buckets + i);