linux-kernel - [PATCH 3.12 73/78] mnt: Move the clear of MNT_LOCKED from copy

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Date:	Fri, 22 Apr 2016 13:05:56 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 73/78] mnt: Move the clear of MNT_LOCKED from copy_tree to it's callers.

From: "Eric W. Biederman" <ebiederm@...ssion.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 8486a7882b5ba906992fd78bbfcefaae7fe285cc upstream.

Clear MNT_LOCKED in the callers of copy_tree except copy_mnt_ns, and
collect_mounts.  In copy_mnt_ns it is necessary to create an exact
copy of a mount tree, so not clearing MNT_LOCKED is important.
Similarly collect_mounts is used to take a snapshot of the mount tree
for audit logging purposes and auditing using a faithful copy of the
tree is important.

This becomes particularly significant when we start setting MNT_LOCKED
on rootfs to prevent it from being unmounted.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Acked-by: NeilBrown <neilb@...e.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 fs/namespace.c | 1 -
 fs/pnode.c     | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index d727b0ce11df..f67473272010 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1416,7 +1416,6 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
 	if (IS_ERR(q))
 		return q;

-	q->mnt.mnt_flags &= ~MNT_LOCKED;
 	q->mnt_mountpoint = mnt->mnt_mountpoint;

 	p = mnt;
diff --git a/fs/pnode.c b/fs/pnode.c
index 9af0df15256e..509d046e2b3e 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -249,6 +249,7 @@ int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
 			list_splice(tree_list, tmp_list.prev);
 			goto out;
 		}
+		child->mnt.mnt_flags &= ~MNT_LOCKED;

 		if (is_subdir(dest_mp->m_dentry, m->mnt.mnt_root)) {
 			mnt_set_mountpoint(m, dest_mp, child);
-- 
2.8.1