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mount: prevent dumping mounts, if they can't be restored (v2)

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Currently we check that all shared mounts have identical set of
children and that Each non-root mount has a proper root mount.

v2: check that nobody is overmounted
    check a tree before trying to restore it.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin 2013-08-13 17:02:51 +04:00 committed by Pavel Emelyanov
parent 6244f943bf
commit 37ffc41863
1 changed files with 71 additions and 0 deletions
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71
mount.c
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@ -27,6 +27,9 @@
static struct mount_info *mntinfo;
int mntns_root = -1;
static DIR *open_mountpoint(struct mount_info *pm);
static int close_mountpoint(DIR *dfd);
static inline int is_root(char *p)
{
return p[0] == '/' && p[1] == '\0';
@ -216,6 +219,68 @@ static void mnt_tree_show(struct mount_info *tree, int off)
pr_info("%*s<--\n", off, "");
}
static int validate_mounts(struct mount_info *info)
{
struct mount_info *m, *t;
for (m = info; m; m = m->next) {
if (m->parent && m->parent->shared_id) {
struct mount_info *ct;
if (list_empty(&m->parent->mnt_share))
continue;
t = list_first_entry(&m->parent->mnt_share, struct mount_info, mnt_share);
list_for_each_entry(ct, &t->children, siblings) {
if (mounts_equal(m, ct, false))
break;
}
if (&ct->siblings == &t->children) {
pr_err("Two shared mounts %d, %d have different sets of children\n",
m->parent->mnt_id, t->mnt_id);
pr_err("%d:%s doesn't have a proper point for %d:%s\n",
t->mnt_id, t->mountpoint,
m->mnt_id, m->mountpoint);
return -1;
}
}
if (m->parent && !fsroot_mounted(m)) {
list_for_each_entry(t, &m->mnt_bind, mnt_bind) {
if (fsroot_mounted(t))
break;
}
if (&t->mnt_bind == &m->mnt_bind) {
pr_err("%d:%s doesn't have a proper root mount\n",
t->mnt_id, t->mountpoint);
return -1;
}
}
if (m->parent == NULL)
continue;
list_for_each_entry(t, &m->parent->children, siblings) {
int tlen, mlen;
if (m == t)
continue;
tlen = strlen(t->mountpoint);
mlen = strlen(m->mountpoint);
if (mlen < tlen)
continue;
if (strncmp(t->mountpoint, m->mountpoint, tlen))
continue;
if (mlen > tlen && m->mountpoint[tlen] != '/')
continue;
pr_err("%d:%s is overmounted", m->mnt_id, m->mountpoint);
return -1;
}
}
return 0;
}
static int collect_shared(struct mount_info *info)
{
struct mount_info *m, *t;
@ -588,6 +653,9 @@ int dump_mnt_ns(int ns_pid, struct cr_fdset *fdset)
if (mnt_build_tree(pm) == NULL)
return -1;
if (validate_mounts(pm))
return -1;
pr_info("Dumping mountpoints\n");
img_fd = fdset_fd(fdset, CR_FD_MNTS);
@ -1110,6 +1178,9 @@ static int populate_mnt_ns(int ns_pid)
if (!pms)
return -1;
if (validate_mounts(pms))
return -1;
return mnt_tree_for_each(pms, do_mount_one);
err:
while (pms) {