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restore: rework logic about temporary proc

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We need proc for restoring processes. The existent /proc may be not suitable.
E.g. If processes are in pidns.

crtools mounts procfs in a temporary directory, but it should be
umounted at the end. Before this patch crtools did that, but
it doesn't work if processes in a mount namespace.

Actually this logic can be simplified and this patch does that.
* create a tmp dir
* mount procfs
* open this directory and save a file descriptor.
* detach procfs
* remove the tmp dir
* access to proc via openat, statat and so on.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin 2012-08-01 15:01:13 +04:00 • committed by Pavel Emelyanov
parent 2f272fa187
commit 2e9ddccdb9
1 changed files with 23 additions and 36 deletions
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59
cr-restore.c
View file

@ -632,40 +632,33 @@ static void restore_pgid(void)
}
}
static char proc_mountpoint[PATH_MAX] = "/proc";
static int prepare_proc(void)
{
snprintf(proc_mountpoint, sizeof(proc_mountpoint), "/tmp/crtools-proc.XXXXXX");
if (mkdtemp(proc_mountpoint) == NULL) {
pr_err("mkdtemp failed %m");
return -1;
}
return 0;
}
static void umount_proc(void)
{
int err;
err = umount(proc_mountpoint);
if (err == -1)
pr_err("Can't umount %s\n", proc_mountpoint);
err = rmdir(proc_mountpoint);
if (err == -1)
pr_err("Can't delete %s\n", proc_mountpoint);
}
static void mount_proc(void)
{
int ret;
char proc_mountpoint[PATH_MAX];
mkdir("/tmp/", 0777);
snprintf(proc_mountpoint, sizeof(proc_mountpoint), "crtools-proc.XXXXXX");
if (mkdtemp(proc_mountpoint) == NULL) {
pr_err("mkdtemp failed %m");
exit(1);
}
pr_info("Mount procfs in %s\n", proc_mountpoint);
ret = mount("proc", proc_mountpoint, "proc", MS_MGC_VAL, NULL);
if (ret == -1) {
pr_err("mount failed");
exit(1);
}
set_proc_mountpoint(proc_mountpoint);
if (umount2(proc_mountpoint, MNT_DETACH) == -1) {
pr_err("Can't umount %s\n", proc_mountpoint);
exit(1);
}
if (rmdir(proc_mountpoint) == -1) {
pr_err("Can't remove %s\n", proc_mountpoint);
exit(1);
}
}
static int restore_task_with_children(void *_arg)
@ -699,6 +692,12 @@ static int restore_task_with_children(void *_arg)
if (ret)
exit(-1);
/*
* We need non /proc proc mount for restoring pid and mount
* namespaces and do not care for the rest of the cases.
* Thus -- mount proc at custom location for any new namespace
*/
mount_proc();
}
@ -777,15 +776,6 @@ static int restore_root_task(struct pstree_item *init, struct cr_options *opts)
return -1;
}
/*
* We need non /proc proc mount for restoring pid and mount namespaces
* and do not care for the rest of the cases. Thus -- mount proc at
* custom location for any new namespace
*/
if (opts->namespaces_flags && prepare_proc())
return -1;
/*
* FIXME -- currently we assume that all the tasks live
* in the same set of namespaces. This is done to debug
@ -832,9 +822,6 @@ static int restore_root_task(struct pstree_item *init, struct cr_options *opts)
ret = (int)futex_get(&task_entries->nr_in_progress);
out:
if (opts->namespaces_flags)
umount_proc();
if (ret < 0) {
struct pstree_item *pi;
pr_err("Someone can't be restored\n");