[PATCH] Btrfs: use WARN_ON_ONCE instead for btrfs_invalidate_inodes

[Liu Bo <bo.li.liu@oracle.com>]

So after transaction is aborted, we need to cleanup inode resources by
calling btrfs_invalidate_inodes(), and btrfs_invalidate_inodes() hopes
roots' refs to be zero in old times and sets a WARN_ON(), however, this
is not always true within cleaning up transaction, so WARN_ON_ONCE() is
better, and we won't get another syslog message bomb.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f1a7744..ef7f6af 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4761,7 +4761,7 @@ void btrfs_invalidate_inodes(struct btrfs_root *root)
 	struct inode *inode;
 	u64 objectid = 0;
 
-	WARN_ON(btrfs_root_refs(&root->root_item) != 0);
+	WARN_ON_ONCE(btrfs_root_refs(&root->root_item) != 0);
 
 	spin_lock(&root->inode_lock);
 again:
-- 
1.8.2.1