A few sentences, which are required for understanging this patch
2a) A shared mount can be replicated to as many mountpoints and all the
replicas continue to be exactly same.
2b) A slave mount is like a shared mount except that mount and umount
events only propagate towards it.
2c) A private mount does not forward or receive propagation.
All rules is there Documentation/filesystems/sharedsubtree.txt
If it's a first mount in a group, all group members should be
bind-mounted from this one.
Each mount propagates to all members of parent's group. The group can
contains a few slaves.
Mounts, which have propagated to slaves, are unmounted, because we can't
be sure, that they propagated in real life. For example:
mount --bind --make-slave /share /slave1
mount --bind --make-slave /share /slave2
mount /share/test
umount /slave2/test
mount --make-share /slave1/test
mount --bind --make-share /slave1/test /slave2/test
41 40 0:33 / /share rw,relatime shared:28 - tmpfs xxx rw
42 40 0:33 / /slave1 rw,relatime master:28 - tmpfs xxx rw
43 40 0:33 / /slave2 rw,relatime master:28 - tmpfs xxx rw
44 41 0:34 / /share/test rw,relatime shared:29 - tmpfs xxx rw
46 42 0:34 / /slave1/test rw,relatime shared:30 master:29 - tmpfs xxx rw
45 43 0:34 / /slave2/test rw,relatime shared:30 master:29 - tmpfs xxx rw
/slave1/test and /slave2/test depend on each other and minimum one of them
doesn't propagate from /share/test
v2: use false and true for bool
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Try to restore mounts while a postpone list isn't empty and check
that each iteration has some progress, otherwice it will fails for
preventing infinite loops
v2: rework logic about postpone list
add more comments
v3: one more attempt to make it more readable
v4: Here is a master class from Pavel how to write self-documented code.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
They are required for restoring shared and slave mounts
v2: use the same names of variables in image and in code
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
All shared mounts from one group are connected to circular list.
All slave are added into the proper master list.
v2: change variable name and fix a bug about adding shared mounts in a
circular list.
v3: handle errors of collect_shared
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
It's a special case, because if we've split the stack vma,
only the lowest one has the guard page.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
In /proc/pid/maps grow-down VMA-s are shown without guard pages, but
sometime these "guard" pages can contain usefull data. For example if
a real guard page has been remmaped by another VMA. Let's call such
pages as fake guard pages.
So when a grow-down VMA is mmaped on restore, it should be mapped with
one more guard page to restore content of the fake guard page.
https://bugzilla.openvz.org/show_bug.cgi?id=2715
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The kernel logic is described in v2.6.36-rc1-161-g7798330:
"If we've split the stack vma, only the lowest one has the guard page."
https://bugzilla.openvz.org/show_bug.cgi?id=2715
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The current scheme is racy. It use open_detache_mount in a current
name-space. If a mount namespace is created by someone else between
mount and umount(detach) in open_detache_mount, the mount will be
propagated in the new mntns, then it is detached in a current ns and
rmdir fails, because it's still mounted in athother mntns.
This patch creates a new mount namespace for mounting sysfs.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Currently pos has type unsigned long, so its size depends on
architecture. pos is saved as 64-bit value in the image file and it
isn't restored, if it is equal to -1. Due to convertation on 32-bit
platforms -1 is converted into UINT_MAX and we get error on restore.
$ zdtm.sh ns/static/tun
...
(00.398513) 5: Error (files-reg.c:534): Can't restore file pos: Illegal seek
(00.398888) 5: Error (files-reg.c:489): Can't open file /dev/net/tun: Illegal seek
...
id: 0x15 flags: 0x2 pos: 0x000000ffffffff fown: { uid: 0 euid: 0 signum: 0 pid_type: 0 pid: 0 } name: "/dev/net/tun"
crtools is compiled with _FILE_OFFSET_BITS=64, so off_t is always 64-bit.
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
We will need to reuse this code in criu library, where libc calls
are present thus we will be compiling it in shared mode.
Because internal syscalls library won't be needed we wrap them
with __sys macro which would hide the details of invocation depending
on CR_NOGLIBC preprocessor variable passed from command line.
Original-patch-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
It's not a problem now but in future we might need
some special flags to be passed here.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Tun files are attached to tun links, thus we need the latter to
be dumped together with the former.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Reading from NetDeviceEntry directly is not safe
and may cause buffer overflow. Use stlcpy helper.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Same as kernel provides, adopted from Linux sources.
strlcpy is similar to strncpy but _always_ adds \0
at the end of string even if destination is shorter.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The kernel was compiled without the tun driver.
This reverts commit 889a21292f.
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
setuid and setgid drops the dumpable flag, so it should be set back.
Otherwise proccesses will not able to read a few files in proc (e.g.
/proc/pid/pagemap).
This patch affects cow01:
11:50:04.429: 4: ERR: cow01.c:99: Unable to read data (errno = 13 (No such file or directory))
v2: typo fix
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This reverts commit 21d94e0086.
This patch was created for investigating
https://bugzilla.openvz.org/show_bug.cgi?id=2676
The bug is fixed and this patch does nothing useful, because tcpdump
starts too late.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This patch fixes running into loop and data loss, when dumping
semi-closed unix stream connection.
patchv2 has error check, that was missed in v1.
Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
We have generic do_pb_show() call and tons of show_foo
routines, that just call one with proper args. Compact
the code by putting the args into array and calling
the do_pb_show() in one place.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The recv-fd stage is only required if we created any transport fd.
The post-open one is only required if there's at least one fdtype
with post-open callback in ops.
Both things can be evaluated in advance and unneeded stages can
be skipped.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
These contain linkage between number, data type and routines
for pb messages we write/read to/from image files. Most of them
have simple number-type-routines mapping, so introduce a generating
script for that.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
There's some strange setup on Jenkins boxes, so that /dev/net/tun
is inaccessible. Need to check this after holidays :(
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This thing is pretty straightforward -- on netns creation
populate it with tun-s, after this collect tun files, open
and attach them with regular fd-s engine.
One tricky thing -- when populating namespace with tun links
make them all persistent and drop this flag (if required)
later, when the first alive opened appears.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The major issue with dump is -- some info id get via netlink,
some via sysfs and some (!) via opened and attached tun file.
But the latter cannot be created, if there's another one attached
(or the mq device is full with threads).
Thus we have to dump this info via existing tun file and keep one
in memory till the link dump code takes place.
Opposite situation is also possible -- we can have a persistent
unattached device. In this case we have to attach to it, dump
things and detach back.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
There will be two entities handled:
1. tun file -- an opened char device with misc major and tun minor
that can be attached to item #2
2. tun netdevice -- another type of links
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
TUN devices are created with ioctl, but their parameters (e.g.
flags with state, mtu, etc.) are to be restored with generic
RTM_SETLINK message.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
It's not quite clean, but on dump non-seekable files dump 0xff...ff into
64-bit pos field of the image. Thus on restore we'd face an error in the
do_open_reg. In order not to have separate helper for non-seekable files
just skip the position restore for such.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Some information about network devices may hide in sysfs, thus
it's required to have one at hands while dumping the netns.
Create the detached mount for that.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Some (most) network devices would like to have NetDeviceEntry with
more fields, than currently present (and enough for lo and veth).
Prepare for that by allowing them to define their own callback that
would fill the resor of the pb entry and call write_netdev_img().
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The option can run test with specified name directly without check
or match.
It can be used to run experimental test that is not in TEST_LIST.
Signed-off-by: Yicheng Qin <yichengq@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
