From: Christian Brauner <brauner@kernel.org>
Date: Thu, 22 Jan 2026 10:48:46 +0000 (+0100)
Subject: mount: start iterating from start of rbtree
X-Git-Tag: v7.1-rc1~172^2~8^2~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0c0b046392b5b6e2402bf75215ab0c3a242d7af5;p=thirdparty%2Fkernel%2Flinux.git

mount: start iterating from start of rbtree

If the root of the namespace has an id that's greater than the child
we'd not find it. Handle that case.

Link: https://patch.msgid.link/20260122-work-fsmount-namespace-v1-1-5ef0a886e646@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/namespace.c b/fs/namespace.c
index 854f4fc664697..9fd5114e5eb71 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5649,14 +5649,14 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root)
 	if (mnt_ns_empty(ns))
 		return -ENOENT;
 
-	first = child = ns->root;
-	for (;;) {
-		child = listmnt_next(child, false);
-		if (!child)
-			return -ENOENT;
-		if (child->mnt_parent == first)
+	first = ns->root;
+	for (child = node_to_mount(ns->mnt_first_node); child;
+	     child = listmnt_next(child, false)) {
+		if (child != first && child->mnt_parent == first)
 			break;
 	}
+	if (!child)
+		return -ENOENT;
 
 	root->mnt = mntget(&child->mnt);
 	root->dentry = dget(root->mnt->mnt_root);