fs: fix is_mnt_ns_file()

Commit 1fa08aece425 ("nsfs: convert to path_from_stashed() helper") reused
nsfs dentry's d_fsdata, which no longer contains a pointer to
proc_ns_operations.

Fix the remaining use in is_mnt_ns_file().

Fixes: 1fa08aece425 ("nsfs: convert to path_from_stashed() helper")
Cc: stable@vger.kernel.org # v6.9
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20241211121118.85268-1-mszeredi@redhat.com
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index 23e81c2a1e3fee7d97df2a84a69438a677933654..6eec7794f707b343fb4d7daad52fe99b7282456d 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2055,9 +2055,15 @@ SYSCALL_DEFINE1(oldumount, char __user *, name)
 
 static bool is_mnt_ns_file(struct dentry *dentry)
 {
+       struct ns_common *ns;
+
        /* Is this a proxy for a mount namespace? */
-       return dentry->d_op == &ns_dentry_operations &&
-              dentry->d_fsdata == &mntns_operations;
+       if (dentry->d_op != &ns_dentry_operations)
+               return false;
+
+       ns = d_inode(dentry)->i_private;
+
+       return ns->ops == &mntns_operations;
 }
 
 struct ns_common *from_mnt_ns(struct mnt_namespace *mnt)