mount: Allocate mountinfo strings dynamically

On the restore path this structure will be used and it
will be better to have them char * rather than char[64].

When scanning proc use the %ms specifier for this.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Rename struct proc_mountinfo into mount_info

This structure will be used on restore and will be created
from the image, thus the name proc_ is not suitable.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Basic mount points dumping

Dumping is straightforward -- just copy all the mount_info
fields into the new image file. Dump everything but fstype,
this one will come in a separate patch.

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

Encode it in u32 since we have to check filesystem name anyway
(not everyone ie easily migratable).

Dump _any_ root fs as we need the root entry on restore though
do not mount it then -- it should be provided before crtools
restore start.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Build mount points tree out of a plain list

Build a tree of mountpoins that can be (u)mounted in a straight
(forward or backward) order without EBUSY errors.

The tree is built in two steps -- first create hierarchy based
on mount iDs. Next -- resort siblings in the path depth order.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
util: Helper for reading a string from image

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Core for creating mount namespace

Namespace restore goes in two steps -- first, clean old mountpoints
(except root) that are left after clone(CLONE_NEWNS) call. Next,
repopulate the namespace with new mountpoints (except root) read
from the image file.

This patch adds the skeleton for the above -- reading the mountpoints
from current proc and image and calling for mount/umount. The real
action will come in further patches.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Tree walking functions

Two walkers -- in forward and reverse directions -- are required
for correct (u)mounting of subtrees. Implement them using a helper
macro which walks the tree in both directions.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Umount a mountpoint when iterating

The tree should already be sorted, thus the call for umount shouldn't fail.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mount: Mounting code core

Only support virtual filesystems mount. No bindmounts or disk fs
due to non trivial resolving of devices names and binmount sources.
Will be implemented later.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
rst: Create custom proc every time we restore a namespace

We need own proc for restoring mount namespace, since the proc should
be umounted and mounted back diring namespace restore and I don't want
to introduce a special kludge for this.

One more notice -- the temp proc is mounted _after_ namespaces recreation
for the same reason (it will be umounted by prepare_mnt_ns).

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: Basic test for mount points in mount namespace

Test with sysfs and proc as no other fs-s are currently supported.
Will be fixed later.

Note, that the original /proc mount is kept as the dumping code requires
it for reading pagemap file with RSS info. Worth fixing it some day?

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
rst: Close standard descriptors before fds restore

Strictly speaking we have to close all fds before reopening them from the
image. This can be done using not yet merged nextfd syscall, but it's not
yet merged :( By now just close std and 255 (bash's) descriptors. This is
ugly, but I prefer to wait for the nextfd syscall.

But skip the init tasks' stds becase the existing zdtm implementation
uses system() in such tasks which doesn't work when all fds are closed.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: Add task_waiter_ helpers v3

Sometime we need sync points in testee program flow,
for this reason task_waiter_ introduced.

The call semantics is the following

        Parent                  Child
        ------                  -----
        task_waiter_init
                                task_waiter_wait4
        task_waiter_complete
                                task_waiter_wait4
        task_waiter_complete

                ...

Thus initially task_waiter_init should be called
to initialize all internals guts needed.

Then one become waitee and calls for task_waiter_wait4,
where lockid should be provided as an argument. Since
it should be unique values the best option might be
gettid().

The same applies to a waiter side -- it should call
for task_waiter_complete and provide a lockid.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrey Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: Convert caps00 test to use task_waiters

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrey Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: make zdtm.sh faster in two times

It requered 1m19s for executing all tests.
Now it requires 38s.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: don't print useless numbers

expr prints a substing length. This patch redirects output of expr to /dev/null

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
pstree: move all code about pstree in a separate file

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Looks-cool-to: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: allow for 0 timer growth in uptime_grow

It may occur that the loop spins faster than clock ticks.

Signed-off-by: Evgeny Antyshev <eantyshev@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
img: Move all the img files management code to image.c

And clean util.c and crtools.c from image manupulation code.

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