mir/criu
2
0
Fork 0
mirror of https://github.com/checkpoint-restore/criu synced 2025-08-30 22:05:36 +00:00
Code Issues Releases Wiki Activity

mount: setup mnt_bind list before using it in mnt_is_external

Browse Source 
Before this patch mnt_is_external() used non-populated mnt_bind list
when called from resolve_shared_mounts(), thus it could work not as
intended.

Let's add separate helper search_bindmounts() for populating mnt_bind
list, and add mnt_bind_is_populated to differentiate between
non-populated list and just empty populated list. This way we can add a
BUG_ON to mnt_is_external to catch such order problems in future.

Cherry-picked from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/e464c1c6d
Cherry-picked from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/8b22b30d5
Cherry-picked one hunk from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/ca9de41e3

Changes: simplify commit message, merge fixups: search bindmounts
earlier so that we have bindmounts info as early as possible, rename
mnt_no_bind to mnt_bind_is_populated and simplify it's logic a bit.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
This commit is contained in:
Pavel Tikhomirov
2019-12-20 17:26:07 +03:00
committed by Andrei Vagin
parent 30261a7515
commit 261b7a8fd4
2 changed files with 50 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
criu/include/mount.h
View File

@@ -73,6 +73,7 @@ struct mount_info {
struct list_head siblings;
struct list_head mnt_bind; /* circular list of derivatives of one real mount */
bool mnt_bind_is_populated; /* indicate that mnt_bind list is ready to use */
struct list_head mnt_share; /* circular list of shared mounts */
struct list_head mnt_slave_list; /* list of slave mounts */
struct list_head mnt_slave; /* slave list entry */

64
criu/mount.c
View File

@@ -571,6 +571,11 @@ static bool mnt_is_external(struct mount_info *m)
if (t->external)
return 1;
/*
* Shouldn't use mnt_bind list before it was populated in search_bindmounts
*/
BUG_ON(!m->mnt_bind_is_populated);
if (m->master_id <= 0 && !list_empty(&m->mnt_bind))
list_for_each_entry(t, &m->mnt_bind, mnt_bind)
if (issubpath(m->root, t->root) && t->external)
@@ -892,6 +897,43 @@ static int same_propagation_group(struct mount_info *a, struct mount_info *b)
return 0;
}
/*
* Note: Only valid if called consequently on all mounts in mntinfo list.
*
* Note: We may want to iterate over all bindmounts of some mount, and we would
* use ->mnt_bind list for this, but iterating over ->mnt_bind list is
* obviously meaningless before search_bindmounts had actually put bindmounts
* in it. That's why we have ->mnt_bind_is_populated to protect from misuse of
* ->mnt_bind. (As ->mnt_bind list can validly be empty when mount has no
* bindmounts we need separate field to indicate population.)
*/
static void __search_bindmounts(struct mount_info *mi)
{
struct mount_info *t;
if (mi->mnt_bind_is_populated)
return;
for (t = mi->next; t; t = t->next) {
if (mounts_sb_equal(mi, t)) {
list_add(&t->mnt_bind, &mi->mnt_bind);
t->mnt_bind_is_populated = true;
pr_debug("\tThe mount %3d is bind for %3d (@%s -> @%s)\n", t->mnt_id, mi->mnt_id, t->mountpoint,
mi->mountpoint);
}
}
mi->mnt_bind_is_populated = true;
}
static void search_bindmounts(void)
{
struct mount_info *mi;
for (mi = mntinfo; mi; mi = mi->next)
__search_bindmounts(mi);
}
static int resolve_shared_mounts(struct mount_info *info, int root_master_id)
{
struct mount_info *m, *t;
@@ -944,21 +986,6 @@ static int resolve_shared_mounts(struct mount_info *info, int root_master_id)
m->mnt_id, m->mountpoint, m->master_id, m->shared_id);
return -1;
}
/* Search bind-mounts */
if (list_empty(&m->mnt_bind)) {
/*
* A first mounted point will be set up as a source point
* for others. Look at propagate_mount()
*/
for (t = m->next; t; t = t->next) {
if (mounts_sb_equal(m, t)) {
list_add(&t->mnt_bind, &m->mnt_bind);
pr_debug("\tThe mount %3d is bind for %3d (@%s -> @%s)\n", t->mnt_id, m->mnt_id,
t->mountpoint, m->mountpoint);
}
}
}
}
/* Search propagation groups */
@@ -1539,6 +1566,7 @@ static __maybe_unused int add_cr_time_mount(struct mount_info *root, char *fsnam
break;
}
mi->mnt_bind_is_populated = true;
mi->nsid = parent->nsid;
mi->parent = parent;
mi->parent_mnt_id = parent->mnt_id;
@@ -3143,6 +3171,9 @@ int read_mnt_ns_img(void)
}
mntinfo = pms;
search_bindmounts();
return 0;
}
@@ -3320,6 +3351,7 @@ static int populate_mnt_ns(void)
root_yard_mp->mountpoint = mnt_roots;
root_yard_mp->mounted = true;
root_yard_mp->mnt_bind_is_populated = true;
if (merge_mount_trees(root_yard_mp))
return -1;
@@ -3756,6 +3788,8 @@ int collect_mnt_namespaces(bool for_dump)
if (ret)
goto err;
search_bindmounts();
#ifdef CONFIG_BINFMT_MISC_VIRTUALIZED
if (for_dump && !opts.has_binfmt_misc) {
unsigned int s_dev = 0;