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authorMaxim Patlasov <mpatlasov@virtuozzo.com>2016-02-16 11:45:33 -0800
committerSasha Levin <sasha.levin@oracle.com>2016-05-17 17:41:38 -0400
commit66f0487aecd2515b550abc31ede08215cc3279e8 (patch)
treeafb4449a96fd7ac327cf762ac77ca3a87d3997eb /fs
parent12de322789aabf55f41ce73eb5b6a5c33fc4313e (diff)
downloadlinux-linaro-stable-66f0487aecd2515b550abc31ede08215cc3279e8.tar.gz
fs/pnode.c: treat zero mnt_group_id-s as unequal
[ Upstream commit 7ae8fd0351f912b075149a1e03a017be8b903b9a ] propagate_one(m) calculates "type" argument for copy_tree() like this: > if (m->mnt_group_id == last_dest->mnt_group_id) { > type = CL_MAKE_SHARED; > } else { > type = CL_SLAVE; > if (IS_MNT_SHARED(m)) > type |= CL_MAKE_SHARED; > } The "type" argument then governs clone_mnt() behavior with respect to flags and mnt_master of new mount. When we iterate through a slave group, it is possible that both current "m" and "last_dest" are not shared (although, both are slaves, i.e. have non-NULL mnt_master-s). Then the comparison above erroneously makes new mount shared and sets its mnt_master to last_source->mnt_master. The patch fixes the problem by handling zero mnt_group_id-s as though they are unequal. The similar problem exists in the implementation of "else" clause above when we have to ascend upward in the master/slave tree by calling: > last_source = last_source->mnt_master; > last_dest = last_source->mnt_parent; proper number of times. The last step is governed by "n->mnt_group_id != last_dest->mnt_group_id" condition that may lie if both are zero. The patch fixes this case in the same way as the former one. [AV: don't open-code an obvious helper...] Signed-off-by: Maxim Patlasov <mpatlasov@virtuozzo.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/pnode.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/pnode.c b/fs/pnode.c
index aae331a5d03b..97bb597f0b9e 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -202,6 +202,11 @@ static struct mount *last_dest, *last_source, *dest_master;
static struct mountpoint *mp;
static struct hlist_head *list;
+static inline bool peers(struct mount *m1, struct mount *m2)
+{
+ return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id;
+}
+
static int propagate_one(struct mount *m)
{
struct mount *child;
@@ -212,7 +217,7 @@ static int propagate_one(struct mount *m)
/* skip if mountpoint isn't covered by it */
if (!is_subdir(mp->m_dentry, m->mnt.mnt_root))
return 0;
- if (m->mnt_group_id == last_dest->mnt_group_id) {
+ if (peers(m, last_dest)) {
type = CL_MAKE_SHARED;
} else {
struct mount *n, *p;
@@ -223,7 +228,7 @@ static int propagate_one(struct mount *m)
last_source = last_source->mnt_master;
last_dest = last_source->mnt_parent;
}
- if (n->mnt_group_id != last_dest->mnt_group_id) {
+ if (!peers(n, last_dest)) {
last_source = last_source->mnt_master;
last_dest = last_source->mnt_parent;
}