When we are doing pre-dump, we splice pages in pipes and only then open
images and dump pages. But when we are splicing pages, we need to know
about existence of parent images. This patch adds a new call to determin
existence of parent images.

In addition this patch fixes a following issue:
CID 83244 (#1 of 1): Uninitialized pointer read (UNINIT)
14. uninit_use: Using uninitialized value xfer.parent.

v2: initialize unused field of struct page_server_iov, because it sends
in network.

CID 83451 (#1 of 1): Uninitialized scalar variable (UNINIT)
2. uninit_use_in_call: Using uninitialized value pi. Field pi.nr_pages
is uninitialized when calling write.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

For stream sockets it's possiable and we should not fail in this case.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Need to print a mask of events for UNKNOWN event in inotify_system_nodel.c
and inotify_system.c tests. The current error message in this case is too vague:
inotify_system_nodel.c:266: got unexpected event UNKNOWN
Signed-off-by: vkonyashkin <vkonyashkin@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

It is in mainline and required for proper CRIU work.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

And move the 2nd piece lower to avoid fwd declaration and
keep similar calls close to each other.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Reported-by: Mr Jenkins
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Here is an example from a fedora container:
65 64 252:0 /vz/private/1 / rw,relatime shared:29 - ext4 /dev/mapper/centos_pcs-root rw,data=ordered
77 65 252:0 /vz/private/1/var/tmp/systemd-httpd.service-XLnJPNc/tmp /var/tmp rw,relatime shared:41 - ext4 /dev/mapper/centos_pcs-root rw,data=ordered

We can see non-root shared mount, which is mounted to the root
mount from the same shared group. The test emulates this situation.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Fedora bind-mounts a part of the root mount to itself. Currently we
don't allow to mount children of a shared mount, if other mount from
this shared group are not mounted.

This patch adds an exclusion for cases, when a child has the same
group. We allow to mount a child, if wider mounts are mounted.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Currently we connect roots of sub-namespaces to the root of the root
mount namespace. And we get problems, if the root of the root mntns is
shared, because all children of a shared mount must be propagated to
other mounts in this group.

Actually we mount tmpfs in mnt_roots and here is nothing wrong to add it
in a tree.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

And use the expression for it, it's quite short. This
makes the amount of variables in the code fit into brains.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Do paths conversions and checks step-by-step and add many comments
what we do in each step and why.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

When we check whether a submount of a mount is visible in another
mount (shared peer of the latter), we can and should use the new
issubpath helper.

Should because the used strncmp may scan beyond ct_mpnt_rpath if
its length is smaller (no checks for this in the code).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

These are constant for given m, so calculate them outside
of the loop. Also rename them to reflect what they are.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

The path lenght is zero for the "/" one and strlen(path)
for all the others. This is done so to make it possible
to use this length to get tail-paths: if path_1 starts
with path_2 and both are absolute, then

   path_1 + path_length(path_2)

would give the tail of the tail of path_1 relative to
path_2 even if the path_2 is just "/".
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

A problem which is solved in this path is that some children can be
unaccessiable (unvisiable) for non-root bind-mounts

root	mount point
-------------------
/	/a (shared:1)
/	/a/x
/	/a/x/y
/	/a/z
/x	/b (shared:1)
/	/b/y

/b is a non-root bind-mount of /a
/y is visiable to both mounts
/z is vidiable only for /a

Before this patch we checked that the set of children is the same for
all mount in a shared group. Now we check that a visiable set of mounts
is the same for all mounts in a shared group.

Now we take the next mount in the shared group, which is wider or equal
to current and compare children between them.

Before this patch validate_shared(m) validates the m->parent mount.
Now it validates the "m" mount. So you can find following lines in the
patch:
-               if (m->parent->shared_id && validate_shared(m))
+               if (m->shared_id && validate_shared(m))

We doesn't support shared mounts with different set of children.
Here is an example of such case can be created:
mount tmpfs a /a
mount --make-shared /a
mkdir /a/b
mount tmpfs b /a/b
mount --bind /a /c

In this case /c doesn't have the /b child. To support such cases,
we need to sort all shared mounts accoding with a set of children.

v2: If root is equal to "/", its len should be zero. We expect that the
last symbol in a path is not "/".
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

expr ns/user/static/env00 ns/user
expr: syntax error
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Make their name look similar.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

We have sanity check for zombie-with kids below, no
need in additional.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

We scan threads and children list several times while freezing
the tree, this is done to avoid race with new threads/kids
appearing.

Factor out the iterations code.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

To make the threads collect code be structured similar to
children collect. This will also help in further patching.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Keeping the whole stat buf it too much information.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Right now it returns the whole struct stat which is excessive.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Not to spoil the global namespace and unify the kerndat
data names.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Currently this test creates one process and wait it. So most part of the
time this test has only one process without children.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

For other tests set of file descriptors can be changed
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>