[lxc-devel] [PATCH] c/r: tell CRIU about all external mounts in the config
Tycho Andersen
tycho.andersen at canonical.com
Fri Apr 3 22:29:22 UTC 2015
On Fri, Apr 03, 2015 at 09:41:03PM +0000, Serge Hallyn wrote:
> Quoting Tycho Andersen (tycho.andersen at canonical.com):
> > Signed-off-by: Tycho Andersen <tycho.andersen at canonical.com>
> > ---
> > src/lxc/conf.c | 18 +++++++++++---
> > src/lxc/conf.h | 2 ++
> > src/lxc/list.h | 11 +++++++++
> > src/lxc/lxccontainer.c | 67 +++++++++++++++++++++++++++++++++++++++++++-------
> > 4 files changed, 85 insertions(+), 13 deletions(-)
> >
> > diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> > index 2868708..f9c7e37 100644
> > --- a/src/lxc/conf.c
> > +++ b/src/lxc/conf.c
> > @@ -2040,18 +2040,16 @@ static int setup_mount(const struct lxc_rootfs *rootfs, const char *fstab,
> > return ret;
> > }
> >
> > -static int setup_mount_entries(const struct lxc_rootfs *rootfs, struct lxc_list *mount,
> > - const char *lxc_name)
> > +FILE *write_mount_file(struct lxc_list *mount)
> > {
> > FILE *file;
> > struct lxc_list *iterator;
> > char *mount_entry;
> > - int ret;
> >
> > file = tmpfile();
> > if (!file) {
> > ERROR("tmpfile error: %m");
> > - return -1;
> > + return NULL;
> > }
> >
> > lxc_list_for_each(iterator, mount) {
> > @@ -2060,6 +2058,18 @@ static int setup_mount_entries(const struct lxc_rootfs *rootfs, struct lxc_list
> > }
> >
> > rewind(file);
> > + return file;
> > +}
> > +
> > +static int setup_mount_entries(const struct lxc_rootfs *rootfs, struct lxc_list *mount,
> > + const char *lxc_name)
> > +{
> > + FILE *file;
> > + int ret;
> > +
> > + file = write_mount_file(mount);
> > + if (!file)
> > + return -1;
> >
> > ret = mount_file_entries(rootfs, file, lxc_name);
> >
> > diff --git a/src/lxc/conf.h b/src/lxc/conf.h
> > index 334ea70..4b66045 100644
> > --- a/src/lxc/conf.h
> > +++ b/src/lxc/conf.h
> > @@ -25,6 +25,7 @@
> >
> > #include "config.h"
> >
> > +#include <stdio.h>
> > #include <netinet/in.h>
> > #include <net/if.h>
> > #include <sys/param.h>
> > @@ -422,4 +423,5 @@ extern int parse_mntopts(const char *mntopts, unsigned long *mntflags,
> > extern void tmp_proc_unmount(struct lxc_conf *lxc_conf);
> > void remount_all_slave(void);
> > extern void suggest_default_idmap(void);
> > +FILE *write_mount_file(struct lxc_list *mount);
> > #endif
> > diff --git a/src/lxc/list.h b/src/lxc/list.h
> > index 0882da0..f16af54 100644
> > --- a/src/lxc/list.h
> > +++ b/src/lxc/list.h
> > @@ -99,4 +99,15 @@ static inline void lxc_list_del(struct lxc_list *list)
> > prev->next = next;
> > }
> >
> > +static inline int lxc_list_len(struct lxc_list *list)
> > +{
> > + int i = 0;
> > + struct lxc_list *iter;
> > + lxc_list_for_each(iter, list) {
> > + i++;
> > + }
> > +
> > + return i;
> > +}
> > +
> > #endif
> > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> > index d84543f..7e50372 100644
> > --- a/src/lxc/lxccontainer.c
> > +++ b/src/lxc/lxccontainer.c
> > @@ -35,6 +35,8 @@
> > #include <libgen.h>
> > #include <stdint.h>
> > #include <grp.h>
> > +#include <stdio.h>
> > +#include <mntent.h>
> > #include <sys/syscall.h>
> >
> > #include <lxc/lxccontainer.h>
> > @@ -3513,11 +3515,15 @@ struct criu_opts {
> >
> > static void exec_criu(struct criu_opts *opts)
> > {
> > - char **argv, log[PATH_MAX], buf[257];
> > + char **argv, log[PATH_MAX];
> > int static_args = 14, argc = 0, i, ret;
> > int netnr = 0;
> > struct lxc_list *it;
> >
> > + struct mntent mntent;
> > + char buf[4096];
> > + FILE *mnts = NULL;
> > +
> > /* The command line always looks like:
> > * criu $(action) --tcp-established --file-locks --link-remap --force-irmap \
> > * --manage-cgroups action-script foo.sh -D $(directory) \
> > @@ -3592,6 +3598,21 @@ static void exec_criu(struct criu_opts *opts)
> > if (opts->verbose)
> > DECLARE_ARG("-vvvvvv");
> >
> > +#define RESIZE_ARGS(additional) \
>
> This seems to want to be reused, however it doesn't bump argc,
> so if it is used twice in a row it wont' have the desired effect.
Right, argc is supposedly where the current pointer is, so it
shouldn't bump argc. RESIZE_ARGS has an implicit assumption that
you're out of space when you call it, so you shouldn't call it twice
in a row. I can re-send a patch with a comment to that effect if you
like, or do something else. This whole function is kind of messy now
(and long), so it may be time to rethink it.
Tycho
> > + do { \
> > + void *m; \
> > + if (additional < 0) { \
> > + ERROR("resizing by negative amount"); \
> > + goto err; \
> > + } else if (additional == 0) \
> > + continue; \
> > + \
> > + m = realloc(argv, (argc + additional + 1) * sizeof(*argv)); \
> > + if (!m) \
> > + goto err; \
> > + argv = m; \
> > + } while (0)
> > +
> > if (strcmp(opts->action, "dump") == 0) {
> > char pid[32];
> >
> > @@ -3623,9 +3644,10 @@ static void exec_criu(struct criu_opts *opts)
> > DECLARE_ARG("--cgroup-root");
> > DECLARE_ARG(opts->cgroup_path);
> >
> > + RESIZE_ARGS(lxc_list_len(&opts->c->lxc_conf->network) * 2);
> > +
> > lxc_list_for_each(it, &opts->c->lxc_conf->network) {
> > char eth[128], *veth;
> > - void *m;
> > struct lxc_netdev *n = it->elem;
> >
> > if (n->name) {
> > @@ -3641,18 +3663,42 @@ static void exec_criu(struct criu_opts *opts)
> > if (ret < 0 || ret >= sizeof(buf))
> > goto err;
> >
> > - /* final NULL and --veth-pair eth0=vethASDF */
> > - m = realloc(argv, (argc + 1 + 2) * sizeof(*argv));
> > - if (!m)
> > - goto err;
> > - argv = m;
> > -
> > DECLARE_ARG("--veth-pair");
> > DECLARE_ARG(buf);
> > - argv[argc] = NULL;
> > + }
> > + }
> > +
> > + // CRIU wants to know about any external bind mounts the
> > + // container has.
> > + mnts = write_mount_file(&opts->c->lxc_conf->mount_list);
> > + if (!mnts)
> > + goto err;
> > +
> > + RESIZE_ARGS(lxc_list_len(&opts->c->lxc_conf->mount_list) * 2);
> > +
> > + while (getmntent_r(mnts, &mntent, buf, sizeof(buf))) {
> > + char arg[2048], *key, *val;
> > + int ret;
> >
> > + if (strcmp(opts->action, "dump") == 0) {
> > + key = mntent.mnt_fsname;
> > + val = mntent.mnt_dir;
> > + } else {
> > + key = mntent.mnt_dir;
> > + val = mntent.mnt_fsname;
> > }
> > +
> > + ret = snprintf(arg, sizeof(arg), "%s:%s", key, val);
> > + if (ret < 0 || ret >= sizeof(arg)) {
> > + goto err;
> > + }
> > +
> > + DECLARE_ARG("--ext-mount-map");
> > + DECLARE_ARG(arg);
> > }
> > + fclose(mnts);
> > +
> > + argv[argc] = NULL;
> >
> > netnr = 0;
> > lxc_list_for_each(it, &opts->c->lxc_conf->network) {
> > @@ -3688,8 +3734,11 @@ static void exec_criu(struct criu_opts *opts)
> > }
> >
> > #undef DECLARE_ARG
> > +#undef RESIZE_ARGS
> > execv(argv[0], argv);
> > err:
> > + if (mnts)
> > + fclose(mnts);
> > for (i = 0; argv[i]; i++)
> > free(argv[i]);
> > free(argv);
> > --
> > 2.1.0
> >
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
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