[CRIU] [PATCH] cgroup: don't look up existing mount point
Andrew Vagin
avagin at openvz.org
Tue Jul 15 05:06:41 PDT 2014
A mount point, which is mounted by someone else, may be umounted in any moment.
For example the test system executes tests concurrently and sometimes one
test looks up a mount point, which has been mounted by another test.
==================================== ERROR ====================================
Test: zdtm/live/static/inotify00, Namespace: 1
Dump log : /var/lib/jenkins/jobs/CRIU-dump/workspace/test/dump/inotify00/15535/1/dump.log
--------------------------------- grep Error ---------------------------------
(00.021951) Error (cgroup.c:409): cg: failed walking /var/lib/jenkins/jobs/CRIU-dump/workspace/test/dump/signalfd00/15538/1/.criu.cgmounts.UGj28v/ for empty cgroups
(00.021967) Error (cr-dump.c:1601): Dump core (pid: 15535) failed with -1
(00.025509) Error (cr-dump.c:1914): Dumping FAILED.
------------------------------------- END -------------------------------------
================================= ERROR OVER =================================
Reported-by: Jenkins Criuovich
Cc: Tycho Andersen <tycho.andersen at canonical.com>
Signed-off-by: Andrew Vagin <avagin at openvz.org>
---
cgroup.c | 123 ++++++++++++++-------------------------------------------------
1 file changed, 26 insertions(+), 97 deletions(-)
diff --git a/cgroup.c b/cgroup.c
index 5114935..9ee54d3 100644
--- a/cgroup.c
+++ b/cgroup.c
@@ -14,6 +14,7 @@
#include "proc_parse.h"
#include "util.h"
#include "fdset.h"
+#include "util-pie.h"
#include "protobuf.h"
#include "protobuf/core.pb-c.h"
#include "protobuf/cgroup.pb-c.h"
@@ -44,7 +45,6 @@ static u32 cg_set_ids = 1;
static LIST_HEAD(cgroups);
static unsigned int n_cgroups;
-static struct mount_info *cg_mntinfo;
static CgSetEntry *find_rst_set_by_id(u32 id)
{
@@ -161,53 +161,9 @@ int parse_cg_info(void)
if (parse_cgroups(&cgroups, &n_cgroups) < 0)
return -1;
- cg_mntinfo = parse_mountinfo(getpid(), NULL);
-
- if (!cg_mntinfo)
- return -1;
return 0;
}
-static int get_cgroup_mount_point(const char *controller, char *path)
-{
- struct mount_info *m;
- char name[1024];
-
- for (m = cg_mntinfo; m != NULL; m = m->next) {
- if (strcmp(m->fstype->name, "cgroup") == 0) {
- char *start, *end;
-
- start = strstr(m->options, "name=");
- if (start) {
- /* strlen("name=") == 5 */
- start = start + 5;
-
- end = strstr(start, ",");
- if (end) {
- strncpy(name, start, end - start);
- name[end - start] = '\0';
- } else
- strcpy(name, start);
- } else {
- start = strrchr(m->mountpoint, '/');
- if (!start) {
- pr_err("bad path %s\n", m->mountpoint);
- return -1;
- }
- strcpy(name, start+1);
- }
-
- if (strcmp(name, controller) == 0) {
- /* skip the leading '.' in mountpoint */
- strcpy(path, m->mountpoint + 1);
- return 0;
- }
- }
- }
-
- return -1;
-}
-
/* Check that co-mounted controllers from /proc/cgroups (e.g. cpu and cpuacct)
* are contained in a name from /proc/self/cgroup (e.g. cpu,cpuacct). */
bool cgroup_contains(char **controllers, unsigned int n_controllers, char *name)
@@ -274,7 +230,6 @@ static int add_cgroup(const char *fpath, const struct stat *sb, int typeflag)
if (typeflag == FTW_D) {
int mtype;
- struct mount_info *mi;
strncpy(pbuf, fpath, PATH_MAX);
@@ -287,27 +242,11 @@ static int add_cgroup(const char *fpath, const struct stat *sb, int typeflag)
}
ncd->path = NULL;
- for (mi = cg_mntinfo; mi != NULL; mi = mi->next) {
- if (is_path_prefix(fpath, mi->mountpoint + 1)) {
- ncd->path = xstrdup(fpath + strlen(mi->mountpoint));
- if (!ncd->path) {
- ret = -1;
- goto out;
- }
- break;
- }
- }
-
+ /* chop off the first strlen(".criu.cgmounts.XXXXXX") */
+ ncd->path = xstrdup(fpath + 21);
if (!ncd->path) {
- /* We couldn't find fpath in mountinfo, which means we
- * mounted it ourselves, so we just chop off the first
- * strlen(".criu.cgmounts.XXXXXX").
- */
- ncd->path = xstrdup(fpath + 21);
- if (!ncd->path) {
- ret = -1;
- goto out;
- }
+ ret = -1;
+ goto out;
}
mtype = find_dir(ncd->path, ¤t_controller->heads, &match);
@@ -346,11 +285,11 @@ static int collect_cgroups(struct list_head *ctls)
{
struct cg_ctl *cc;
int ret = 0;
+ int fd = -1;
list_for_each_entry(cc, ctls, l) {
- char path[PATH_MAX];
- char *name, mount_point[PATH_MAX], prefix[] = ".criu.cgmounts.XXXXXX";
- bool temp_mount = false;
+ char path[PATH_MAX], opts[1024];
+ char *name, prefix[] = ".criu.cgmounts.XXXXXX";
struct cg_controller *cg;
if (strstartswith(cc->name, "name="))
@@ -358,34 +297,27 @@ static int collect_cgroups(struct list_head *ctls)
else
name = cc->name;
- if (get_cgroup_mount_point(name, mount_point) < 0) {
- /* Someone is trying to dump a process that is in
- * a controller that isn't mounted, so we mount it for
- * them.
- */
- char opts[1024];
- temp_mount = true;
-
- if (mkdtemp(prefix) == NULL) {
- pr_perror("can't make dir for cg mounts\n");
- return -1;
- }
-
- if (name == cc->name)
- sprintf(opts, "%s", name);
- else
- sprintf(opts, "none,%s", cc->name);
+ if (mkdtemp(prefix) == NULL) {
+ pr_perror("can't make dir for cg mounts\n");
+ return -1;
+ }
- if (mount("none", prefix, "cgroup", 0, opts) < 0) {
- pr_perror("couldn't mount %s\n", opts);
- rmdir(prefix);
- return -1;
- }
+ if (name == cc->name)
+ sprintf(opts, "%s", name);
+ else
+ sprintf(opts, "none,%s", cc->name);
- strcpy(mount_point, prefix);
+ if (mount("none", prefix, "cgroup", 0, opts) < 0) {
+ pr_perror("couldn't mount %s\n", opts);
+ rmdir(prefix);
+ return -1;
}
- snprintf(path, PATH_MAX, "%s/%s", mount_point, cc->path);
+ fd = open_detach_mount(prefix);
+ if (fd < 0)
+ return -1;
+
+ snprintf(path, PATH_MAX, "/proc/self/fd/%d/%s", fd, cc->path);
current_controller = NULL;
@@ -420,10 +352,7 @@ static int collect_cgroups(struct list_head *ctls)
}
out:
- if (temp_mount) {
- umount(prefix);
- rmdir(prefix);
- }
+ close_safe(&fd);
if (ret < 0)
return ret;
--
1.9.3
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