locks: Remove unused arg from dump_one_file_lock

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Parse lock kind earlier

Currently we keep the lock type (posix/flock) till the
time we dump it, then "decode" it into binary value.
I will need the easy-to-check one early, so parse the
kind in proc_parse.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Parse lock type earlier

Same reason as for previous patch.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Don't dump locks in per-task manner (v3)

We have a problem with file locks (bug #2512) -- the /proc/locks
file shows the ID of lock creator, not the owner. Thus, if the
creator died, but holder is still alive, criu fails to dump the
lock held by latter task.

The proposal is to find who _might_ hold the lock by checking
for dev:inode pairs on lock vs file descriptors being dumped.
If the creator of the lock is still alive, then he will take
the priority.

One thing to note about flocks -- these belong to file entries,
not to tasks. Thus, when we meet one, we should check whether
the flock is really held by task's FD by trying to set yet
another one. In case of success -- lock really belongs to fd
we dump, in case it doesn't trylock should fail.

At the very end -- walk the list of locks and dump them all at
once, which is possible by merge of per-task file-locks images
into one global one.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: Check that shared locks work

Shared here means that a flock is visible from two tasks -- the
owner one and its child.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: Check that inherited flocks work

Inherited flock is the one that a task got from its parent.
In case parent closes the corresponding fd, the /proc/locks
still shows the parent pid, while the lock is owned by child.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: Check that overlapping locks work

If we open a file, lock one, fork, then close and
open the file in parent again, lock should 'slide'
to the child process anyway.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: Check that criu's donwgrading quirk works

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
dump: Don't allocate dfds in case we dump shared fdtable

After patches, that dump locks w/o dfds array, we can even
not allocate one when we don't need it.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
fsnotify: fix exit code of dump_inotify_entry()

Return 0 in a success case

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Split lock-in-fd check in a helper

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: When checking for lock being ours handle mand-locks

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: Don't compare PIDs when searching for our locks

Criu may re-lock the lock, thus spoiling the pid, so compare
the file inode number instead.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Don't skip out-of-tree flocks

These guys may have pids that are not met in pstree.
This is not the reason for skipping those, try to
resolve flocks anyway.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
locks: Check for --file-locks option when real locks are found

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
plugin: Beautify criu-plugin.h

 - use custom multiline comments style
 - ending #endif comment

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
plugin: Rework plugins API, v2

Here we define new api to be used in plugins.

 - Plugin should provide a descriptor with help of
   CR_PLUGIN_REGISTER macro, or in case if plugin require
   no init/exit functions -- with CR_PLUGIN_REGISTER_DUMMY.

 - Plugin should define a plugin hook with help of
   CR_PLUGIN_REGISTER_HOOK macro.

 - Now init/exit functions of plugins takes @stage
   argument which tells plugin which stage of criu
   it's been called on dump/restore. For exit it
   also takes @ret which allows plugin to know if
   something went wrong and it needs to cleanup
   own resources.

The idea behind is to not limit plugins authors with names
of functions they might need to use for particular hook.

Such new API deprecates olds plugins structure but to keep
backward compatibility we will provide a tiny layer of
additional code to support old plugins for at least a couple
of release cycles.

For example a trivial plugin might look like

 | #include <sys/types.h>
 | #include <sys/stat.h>
 | #include <fcntl.h>
 | #include <libgen.h>
 | #include <errno.h>
 |
 | #include <sys/socket.h>
 | #include <linux/un.h>
 |
 | #include <stdio.h>
 | #include <stdlib.h>
 | #include <string.h>
 | #include <unistd.h>
 |
 | #include "criu-plugin.h"
 | #include "criu-log.h"
 |
 | static int dump_ext_file(int fd, int id)
 | {
 |	pr_info("dump_ext_file: fd %d id %d\n", fd, id);
 |	return 0;
 | }
 |
 | CR_PLUGIN_REGISTER_DUMMY("trivial")
 | CR_PLUGIN_REGISTER_HOOK(CR_PLUGIN_HOOK__DUMP_EXT_FILE, dump_ext_file)

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
service: Add ability to inherit page server socket

The swrk action is turning out to be a cool thing. We can
spawn criu with swrk action with some FD being open, then
ask for dump/pre-dump/page-server telling it that some
descriptor it needs is "out there".

This patch lets us specify that the page server communication
channel is already in criu's fdtable.

TODO: teach regular service to accept fd via service socket.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
fsnotify: merge inotify wd image into inotify image (v4)

All watch descriptors are collected in a list and then
they are written in inotify image as a repeated field.

This images merge reduces the amount of image files criu
generates and may simplify the fix of mentioned above issue.

v2: use free_inotify_wd_entry() instead of xfree in dump_one_inotify()
v3: don't leak ie.wd_entry
v4: save the original order of watchers
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
fsnotify: merge fanotify mark image into fanotify image (v3)

All marks are collected in a list and then they are written in
the fanotify image as a repeated field.

This images merge reduces the amount of image files criu
generates and may simplify the fix of mentioned above issue

v2: don't leak fe.mark_entry
v3: save the original order of marks
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>