Commit 8318e667 authored Dec 24, 2014 by Eric W. Biederman

mnt: Don't propagate umounts in __detach_mounts



Invoking mount propagation from __detach_mounts is inefficient and
wrong.

It is inefficient because __detach_mounts already walks the list of
mounts that where something needs to be done, and mount propagation
walks some subset of those mounts again.

It is actively wrong because if the dentry that is passed to
__detach_mounts is not part of the path to a mount that mount should
not be affected.

change_mnt_propagation(p,MS_PRIVATE) modifies the mount propagation
tree of a master mount so it's slaves are connected to another master
if possible.  Which means even removing a mount from the middle of a
mount tree with __detach_mounts will not deprive any mount propagated
mount events.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

parent e819f152

fs/namespace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1485,7 +1485,7 @@ void __detach_mounts(struct dentry *dentry)
		lock_mount_hash();
		while (!hlist_empty(&mp->m_list)) {
		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
		umount_tree(mnt, UMOUNT_PROPAGATE);
		umount_tree(mnt, 0);
		}
		unlock_mount_hash();
		put_mountpoint(mp);

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