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>
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>
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>
The proc_parse file turns into a strange pile of homebrew
scanf/fgets/strtok/strchr/etc. combination. I don't like it :(
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Make the proc_mountinfo obtaned after parse form a single linked list.
That's much easier to handle and doesn't have an artificial limitation
of 64 items...
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
What is stored there is the path to mountpoint. The root
is the field previously named "parent root".
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
To restore inotify we need to know the
mount point device numbers, so this helper
parses /proc/pid/mountinfo file for that.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
They are just two next in this file, so extend. This is
required for pgid/sid early read, see next patches for
details.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Since proc_parse.h declares functions which have
list_head as arguments, it should include list.h
and basic types.
Otherwise if included into the files without list support
the compilation might fail as
|
| In file included from cr-check.c:5:
| ./include/proc_parse.h:83: error: expected declaration specifiers or ‘...’ before ‘bool’
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
While we try to seize task it can die and give its pid to
somebody else. This can break pstree consistency. Check for
parent being valid after task is seized.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
This patch tries to introduce lazy and hidden pid_dir support,
meaning one don't have to worry about pid_dir but the optimization
is still there.
The patch relies on the fact that we work with many /proc/pid files for
one pid, then for another pid and so on, i.e. not in a random manner.
The idea is when we call open_proc() with a new pid for the first time,
the appropriate /proc/PID directory is opened and its fd is stored.
Next call to open_proc() with the same PID only need to check that
the PID is not changed. In case PID is changed, we close the old one
and open/store a new one.
Now the code using open_proc() and friends:
- does not need to carry proc_pid around, pid is enough
- does not need to call open_pid_proc()
The only thing that can't be done in that "lazy" mode is closing the last
PID fd, thus close_pid_proc().
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
...and make it correctly print the file name we were unable to open.
Also, error from fdopen[dir]() is now reported with file name as well.
Note that open_proc() and friends need to be macros in order for
pr_perror() to show actual file name and line number where error occured.
Historical note: the original version of this patch was way more radical,
changing openat() to open() and thus removing pid_dir (replacing with pid
when needed) and open_proc_dir(), changing openat() to open(). The word
from Pavel is he wants to keep the openat/pid_dir optimization because
it saves two dentry lookups in kernel code for each open(). Because of
this optimization (and desire to print correct file name in case
of error) we have to carry both pid and pid_dir everywhere.
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
This commit brings the former "Rewrite task/threads stopping engine"
commit back. Handling it separately is too complex so better try
to handle it in-place.
Note some tests might fault, it's expected.
---
Stopping tasks with STOP and proceeding with SEIZE is actually excessive --
the SEIZE if enough. Moreover, just killing a task with STOP is also racy,
since task should be given some time to come to sleep before its proc
can be parsed.
Rewrite all this code to SEIZE task and all its threads from the very beginning.
With this we can distinguish stopped task state and migrate it properly (not
supported now, need to implement).
This thing however has one BIG problem -- after we SEIZE-d a task we should
seize
it's threads, but we should do it in a loop -- reading /proc/pid/task and
seizing
them again and again, until the contents of this dir stops changing (not done
now).
Besides, after we seized a task and all its threads we cannot scan it's children
list once -- task can get reparented to init and any task's child can call clone
with CLONE_PARENT flag thus repopulating the children list of the already seized
task (not done also)
This patch is ugly, yes, but splitting it doesn't help to review it much, sorry
:(
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Stopping tasks with STOP and proceeding with SEIZE is actually excessive --
the SEIZE if enough. Moreover, just killing a task with STOP is also racy,
since task should be given some time to come to sleep before its proc
can be parsed.
Rewrite all this code to SEIZE task and all its threads from the very beginning.
With this we can distinguish stopped task state and migrate it properly (not
supported now, need to implement).
This thing however has one BIG problem -- after we SEIZE-d a task we should seize
it's threads, but we should do it in a loop -- reading /proc/pid/task and seizing
them again and again, until the contents of this dir stops changing (not done now).
Besides, after we seized a task and all its threads we cannot scan it's children
list once -- task can get reparented to init and any task's child can call clone
with CLONE_PARENT flag thus repopulating the children list of the already seized
task (not done also)
This patch is ugly, yes, but splitting it doesn't help to review it much, sorry :(
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
All the IDs and caps are in there. Just read them for future use.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Requires patch #14 (for kernel). Also check for number of entries read be
at least required, not exactly equal for forward compatibility.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
And do not use strcpy, better to stick with strncpy.
Moreover, to be on a safe side make proc internal
buffer big enough even for "(%16s)" format, it's
hardly possible that the kernel ever change stat
format but just to be on a safe side.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
We will later need other fields of this file, so let's parse it right
now in a way, that allows to easily get new fields.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
