@@ -1361,6 +1361,36 @@ enum umount_tree_flags {
UMOUNT_PROPAGATE = 2,
UMOUNT_CONNECTED = 4,
};
+
+static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)
+{
+ /* Leaving mounts connected is only valid for lazy umounts */
+ if (how & UMOUNT_SYNC)
+ return true;
+
+ /* A mount without a parent has nothing to be connected to */
+ if (!mnt_has_parent(mnt))
+ return true;
+
+ /* Because the reference counting rules change when mounts are
+ * unmounted and connected, umounted mounts may not be
+ * connected to mounted mounts.
+ */
+ if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT))
+ return true;
+
+ /* Has it been requested that the mount remain connected? */
+ if (how & UMOUNT_CONNECTED)
+ return false;
+
+ /* Is the mount locked such that it needs to remain connected? */
+ if (IS_MNT_LOCKED(mnt))
+ return false;
+
+ /* By default disconnect the mount */
+ return true;
+}
+
/*
* mount_lock must be held
* namespace_sem must be held for write
@@ -1398,10 +1428,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
if (how & UMOUNT_SYNC)
p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
- disconnect = !(((how & UMOUNT_CONNECTED) &&
- mnt_has_parent(p) &&
- (p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) ||
- IS_MNT_LOCKED_AND_LAZY(p));
+ disconnect = disconnect_mount(p, how);
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
disconnect ? &unmounted : NULL);
@@ -1538,11 +1565,8 @@ void __detach_mounts(struct dentry *dentry)
while (!hlist_empty(&mp->m_list)) {
mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
- struct mount *p, *tmp;
- list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) {
- hlist_add_head(&p->mnt_umount.s_list, &unmounted);
- umount_mnt(p);
- }
+ hlist_add_head(&mnt->mnt_umount.s_list, &unmounted);
+ umount_mnt(mnt);
}
else umount_tree(mnt, UMOUNT_CONNECTED);
}
@@ -20,8 +20,6 @@
#define SET_MNT_MARK(m) ((m)->mnt.mnt_flags |= MNT_MARKED)
#define CLEAR_MNT_MARK(m) ((m)->mnt.mnt_flags &= ~MNT_MARKED)
#define IS_MNT_LOCKED(m) ((m)->mnt.mnt_flags & MNT_LOCKED)
-#define IS_MNT_LOCKED_AND_LAZY(m) \
- (((m)->mnt.mnt_flags & (MNT_LOCKED|MNT_SYNC_UMOUNT)) == MNT_LOCKED)
#define CL_EXPIRE 0x01
#define CL_SLAVE 0x02
Linus, Please pull the for-linus branch from the git tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus HEAD: fe78fcc85a2046c51f1535710996860557eeec20 mnt: In detach_mounts detach the appropriate unmounted mount While reading through the code of detach_mounts I realized the code was a slightly off. Testing it revealed two buggy corner cases that can send the code of detach_mounts into an infinite loop. Fixing the code to do the right thing removes the possibility of these user triggered infinite loops in the code. Eric W. Biederman (2): mnt: Clarify and correct the disconnect logic in umount_tree mnt: In detach_mounts detach the appropriate unmounted mount fs/namespace.c | 42 +++++++++++++++++++++++++++++++++--------- fs/pnode.h | 2 -- 2 files changed, 33 insertions(+), 11 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html