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>
criu
====
An utility to checkpoint/restore tasks. Using this tool, you can
freeze a running application (or part of it) and checkpoint it to
a hard drive as a collection of files. You can then use the files
to restore and run the application from the point it was frozen
at. The distinctive feature of the CRIU project is that it is
mainly implemented in user space.
The project home is at http://criu.org
Pages worth starting with are
* Kernel configuration, compilation, etc: http://criu.org/Installation
* A simple example of usage: http://criu.org/Simple_loop
* More sophisticated example with graphical app: http://criu.org/VNC
1cf5168cab