On Wed, 2024-12-11 at 13:11 +0100, Miklos Szeredi wrote:

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

---

Came across this while getting the mnt_ns in fsnotify_mark(), tested the fix in that context. I don't have a test for mainline, though.

fs/namespace.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c index 23e81c2a1e3f..6eec7794f707 100644 --- 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)

Took me a min to figure out how i_private gets set, but this looks correct.

Reviewed-by: Jeff Layton jlayton@kernel.org