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mnt_ns_tree_remove(): DTRT if mnt_ns had never been added to mnt_ns_list

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Actual removal is done under the lock, but for checking if need to bother
the lockless RB_EMPTY_NODE() is safe - either that namespace had never
been added to mnt_ns_tree, in which case the the node will stay empty, or
whoever had allocated it has called mnt_ns_tree_add() and it has already
run to completion.  After that point RB_EMPTY_NODE() will become false and
will remain false, no matter what we do with other nodes in the tree.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-08-26 16:35:55 -04:00
parent b320789d68
commit 38f4885088
1 changed files with 1 additions and 1 deletions
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2
fs/namespace.c
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@ -187,7 +187,7 @@ static void mnt_ns_release_rcu(struct rcu_head *rcu)
static void mnt_ns_tree_remove(struct mnt_namespace *ns)
{
/* remove from global mount namespace list */
if (!is_anon_ns(ns)) {
if (!RB_EMPTY_NODE(&ns->mnt_ns_tree_node)) {
mnt_ns_tree_write_lock();
rb_erase(&ns->mnt_ns_tree_node, &mnt_ns_tree);
list_bidir_del_rcu(&ns->mnt_ns_list);