Subject: linux-next: manual merge of the vfs tree with the vfs-brauner tree

From: Mark Brown <[email-masked]>
Date: Mon, 22 Sep 2025 09:58:45 +0100

Hi all,

Today's linux-next merge of the vfs tree got a conflict in:

  fs/namespace.c

between commit:

  be5f21d3985f0 ("ns: add ns_common_free()")

from the vfs-brauner tree and commit:

  7bb4c851dcb7a ("copy_mnt_ns(): use the regular mechanism for freeing empty mnt_ns on failure")

from the vfs tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

diff --cc fs/namespace.c
index 880cbabe6f957,b9430a5cc987f..0000000000000
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@@ -90,7 -80,16 +90,15 @@@ static DECLARE_RWSEM(namespace_sem)
  static HLIST_HEAD(unmounted);	/* protected by namespace_sem */
  static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */
  static struct mnt_namespace *emptied_ns; /* protected by namespace_sem */
 -static DEFINE_SEQLOCK(mnt_ns_tree_lock);
  
+ static inline void namespace_lock(void);
+ static void namespace_unlock(void);
+ DEFINE_LOCK_GUARD_0(namespace_excl, namespace_lock(), namespace_unlock())
+ DEFINE_LOCK_GUARD_0(namespace_shared, down_read(&namespace_sem),
+ 				      up_read(&namespace_sem))
+ 
+ DEFINE_FREE(mntput, struct vfsmount *, if (!IS_ERR(_T)) mntput(_T))
+ 
  #ifdef CONFIG_FSNOTIFY
  LIST_HEAD(notify_list); /* protected by namespace_sem */
  #endif
@@@ -3229,7 -3304,7 +3244,7 @@@ static int do_reconfigure_mnt(const str
   * If you've mounted a non-root directory somewhere and want to do remount
   * on it - tough luck.
   */
- static int do_remount(struct path *path, int sb_flags,
 -static int do_remount(const struct path *path, int ms_flags, int sb_flags,
++static int do_remount(const struct path *path, int sb_flags,
  		      int mnt_flags, void *data)
  {
  	int err;
@@@ -4164,10 -4204,7 +4133,8 @@@ struct mnt_namespace *copy_mnt_ns(u64 f
  		copy_flags |= CL_SLAVE;
  	new = copy_tree(old, old->mnt.mnt_root, copy_flags);
  	if (IS_ERR(new)) {
+ 		emptied_ns = new_ns;
 +		namespace_unlock();
- 		ns_common_free(ns);
- 		dec_mnt_namespaces(new_ns->ucounts);
- 		mnt_ns_release(new_ns);
  		return ERR_CAST(new);
  	}
  	if (user_ns != ns->user_ns) {
@@@ -4205,14 -4241,7 +4171,7 @@@
  		while (p->mnt.mnt_root != q->mnt.mnt_root)
  			p = next_mnt(skip_mnt_tree(p), old);
  	}
- 	namespace_unlock();
- 
- 	if (rootmnt)
- 		mntput(rootmnt);
- 	if (pwdmnt)
- 		mntput(pwdmnt);
- 
 -	mnt_ns_tree_add(new_ns);
 +	ns_tree_add_raw(new_ns);
  	return new_ns;
  }
  
@@@ -6095,14 -6093,12 +6027,12 @@@ void __init mnt_init(void
  
  void put_mnt_ns(struct mnt_namespace *ns)
  {
 -	if (!refcount_dec_and_test(&ns->ns.count))
 +	if (!ns_ref_put(ns))
  		return;
- 	namespace_lock();
+ 	guard(namespace_excl)();
  	emptied_ns = ns;
- 	lock_mount_hash();
+ 	guard(mount_writer)();
  	umount_tree(ns->root, 0);
- 	unlock_mount_hash();
- 	namespace_unlock();
  }
  
  struct vfsmount *kern_mount(struct file_system_type *type)