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-rw-r--r--fs/namespace.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 044134315f93..77ffdb82f63f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -667,6 +667,41 @@ struct vfsmount *lookup_mnt(struct path *path)
return m;
}
+/*
+ * __is_local_mountpoint - Test to see if dentry is a mountpoint in the
+ * current mount namespace.
+ *
+ * The common case is dentries are not mountpoints at all and that
+ * test is handled inline. For the slow case when we are actually
+ * dealing with a mountpoint of some kind, walk through all of the
+ * mounts in the current mount namespace and test to see if the dentry
+ * is a mountpoint.
+ *
+ * The mount_hashtable is not usable in the context because we
+ * need to identify all mounts that may be in the current mount
+ * namespace not just a mount that happens to have some specified
+ * parent mount.
+ */
+bool __is_local_mountpoint(struct dentry *dentry)
+{
+ struct mnt_namespace *ns = current->nsproxy->mnt_ns;
+ struct mount *mnt;
+ bool is_covered = false;
+
+ if (!d_mountpoint(dentry))
+ goto out;
+
+ down_read(&namespace_sem);
+ list_for_each_entry(mnt, &ns->list, mnt_list) {
+ is_covered = (mnt->mnt_mountpoint == dentry);
+ if (is_covered)
+ break;
+ }
+ up_read(&namespace_sem);
+out:
+ return is_covered;
+}
+
static struct mountpoint *new_mountpoint(struct dentry *dentry)
{
struct hlist_head *chain = mp_hash(dentry);