Unverified Commit 2f576220 authored Feb 21, 2025 by Christian Brauner

fs: add mnt_ns_empty() helper

Add a helper that checks whether a give mount namespace is empty instead
of open-coding the specific data structure check. This also be will be
used in follow-up patches.

Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-2-dbcfcb98c676@kernel.org

Signed-off-by: Christian Brauner <brauner@kernel.org>

parent 3b0cdba4

fs/mount.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -157,6 +157,11 @@ static inline bool mnt_ns_attached(const struct mount *mnt)
		return !RB_EMPTY_NODE(&mnt->mnt_node);
		}

		static inline bool mnt_ns_empty(const struct mnt_namespace *ns)
		{
		return RB_EMPTY_ROOT(&ns->mounts);
		}

		static inline void move_from_ns(struct mount mnt, struct list_head dt_list)
		{
		struct mnt_namespace *ns = mnt->mnt_ns;

fs/namespace.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -5315,7 +5315,7 @@ static int grab_requested_root(struct mnt_namespace ns, struct path root)
		* We have to find the first mount in our ns and use that, however it
		* may not exist, so handle that properly.
		*/
		if (RB_EMPTY_ROOT(&ns->mounts))
		if (mnt_ns_empty(ns))
		return -ENOENT;

		first = child = ns->root;
		@@ -5340,7 +5340,7 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
		int err;

		/* Has the namespace already been emptied? */
		if (mnt_ns_id && RB_EMPTY_ROOT(&ns->mounts))
		if (mnt_ns_id && mnt_ns_empty(ns))
		return -ENOENT;

		s->mnt = lookup_mnt_in_ns(mnt_id, ns);