btrfs: check link counter overflow in link(2)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4822b31..04babaf 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4837,6 +4837,9 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
        if (root->objectid != BTRFS_I(inode)->root->objectid)
                return -EXDEV;
 
+       if (inode->i_nlink == ~0U)
+               return -EMLINK;
+
        btrfs_inc_nlink(inode);
        inode->i_ctime = CURRENT_TIME;