Unverified Commit 3b0cdba4 authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: record sequence number of origin mount namespace 

Store the sequence number of the mount namespace the anonymous mount
namespace has been created from. This information will be used in
follow-up patches.

Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-1-dbcfcb98c676@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 822c1159

fs/mount.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ struct mnt_namespace { 
		wait_queue_head_t	poll;

		struct rcu_head		mnt_ns_rcu;

	};

	u64			seq_origin; /* Sequence number of origin mount namespace */

	u64 event;

	unsigned int		nr_mounts; /* # of mounts in the namespace */

	unsigned int		pending_mounts;

fs/namespace.c

+17 −2
Original line number Diff line number Diff line
@@ -2853,15 +2853,30 @@ static int do_loopback(struct path *path, const char *old_name, 


static struct file *open_detached_copy(struct path *path, bool recursive)

{

	struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;

	struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true);

	struct mnt_namespace *ns, *mnt_ns = current->nsproxy->mnt_ns, *src_mnt_ns;

	struct user_namespace *user_ns = mnt_ns->user_ns;

	struct mount *mnt, *p;

	struct file *file;



	ns = alloc_mnt_ns(user_ns, true);

	if (IS_ERR(ns))

		return ERR_CAST(ns);



	namespace_lock();



	/*

	 * Record the sequence number of the source mount namespace.

	 * This needs to hold namespace_sem to ensure that the mount

	 * doesn't get attached.

	 */

	if (is_mounted(path->mnt)) {

		src_mnt_ns = real_mount(path->mnt)->mnt_ns;

		if (is_anon_ns(src_mnt_ns))

			ns->seq_origin = src_mnt_ns->seq_origin;

		else

			ns->seq_origin = src_mnt_ns->seq;

	}



	mnt = __do_loopback(path, recursive);

	if (IS_ERR(mnt)) {

		namespace_unlock();