From aed434ada68573549d9f5106cde26b94c48e51c2 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 12 May 2015 12:22:47 -0400 Subject: [PATCH] namei: be careful with mountpoint crossings in follow_dotdot_rcu() Otherwise we are risking a hard error where nonlazy restart would be the right thing to do; it's a very narrow race with mount --move and most of the time it ends up being completely harmless, but it's possible to construct a case when we'll get a bogus hard error instead of falling back to non-lazy walk... For one thing, when crossing _into_ overmount of parent we need to check for mount_lock bumps when we get NULL from __lookup_mnt() as well. For another, and less exotically, we need to make sure that the data fetched in follow_up_rcu() had been consistent. ->mnt_mountpoint is pinned for as long as it is a mountpoint, but we need to check mount_lock after fetching to verify that. Signed-off-by: Al Viro --- Reading git-format-patch failed