diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index eec33b9..8938174 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2192,7 +2192,14 @@
 				continue;
 			}
 			nr_truncate++;
+			/*
+			 * Need to hold the imutex for reservation purposes, not
+			 * a huge deal here but I have a WARN_ON in
+			 * btrfs_delalloc_reserve_space to catch offenders.
+			 */
+			mutex_lock(&inode->i_mutex);
 			ret = btrfs_truncate(inode);
+			mutex_unlock(&inode->i_mutex);
 		} else {
 			nr_unlink++;
 		}
@@ -6342,7 +6349,10 @@
 	u64 page_start;
 	u64 page_end;
 
+	/* Need this to keep space reservations serialized */
+	mutex_lock(&inode->i_mutex);
 	ret  = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE);
+	mutex_unlock(&inode->i_mutex);
 	if (!ret)
 		ret = btrfs_update_time(vma->vm_file);
 	if (ret) {