[CRIU] [PATCH] mount: resolve parent mount of symbolic link correctly

[Pavel Emelyanov]

On 07/28/2016 12:11 AM, Katerina Koukiou wrote:
> 
> 
> On Wed, Jul 27, 2016 at 1:39 AM, Andrew Vagin <avagin at virtuozzo.com <mailto:avagin at virtuozzo.com>> wrote:
> 
>     On Tue, Jul 26, 2016 at 04:15:35PM +0300, Pavel Emelyanov wrote:
>     > On 07/26/2016 01:42 AM, Andrew Vagin wrote:
>     > > On Mon, Jul 25, 2016 at 02:26:01PM +0000, Katerina Koukiou wrote:
>     > >> When using --root option in criu dump, when the mountpoint passed
>     > >> contains a symbolic link, criu does not resolve its parent correctly.
>     > >> e.g when passing --root /run/rootfs, dump finishes successfully;
>     > >> but when /var/run/rootfs is passed, where /var/run is symbolic link to
>     > >> /run it exits with error "New root and old root are the same".
>     > >>
>     > >> Signed-off-by: Katerina Koukiou <k.koukiou at gmail.com <mailto:k.koukiou at gmail.com>>
>     > >> ---
>     > >>  criu/mount.c | 10 +++++++++-
>     > >>  1 file changed, 9 insertions(+), 1 deletion(-)
>     > >>
>     > >> diff --git a/criu/mount.c b/criu/mount.c
>     > >> index 7c280c0..0cd83af 100644
>     > >> --- a/criu/mount.c
>     > >> +++ b/criu/mount.c
>     > >> @@ -3420,6 +3420,8 @@ int prepare_mnt_ns(void)
>     > >>                    return -1;
>     > >>    } else {
>     > >>            struct mount_info *mi;
>     > >> +          char *ret;
>     > >> +          char path[PATH_MAX + 1];
>     > >
>     > > PATH_MAX is enough, it includes '\0'
>     > >>
>     > >>            /*
>     > >>             * The whole tree of mountpoints is to be moved into one
>     > >> @@ -3428,8 +3430,14 @@ int prepare_mnt_ns(void)
>     > >>             * with a single umount call later.
>     > >>             */
>     > >>
>     > >> +          ret = realpath(opts.root, path);
>     > >
>     > > realpath returns a string, but a type of ret is int.
>     >
>     > No, there's new char *ret in this block :)
> 
>     Sorry, I haven't noticed this. Thanks.
> 
> 
> It's ugly indeed. I can send a v2 without using ret for the check if needed.

No worries, I can fix this right in the patch :)

> Btw, any idea why the test suite currently fails on zdtm/static/helper_zombie_child
> test on restore?
> 
>     >
>     > >> +          if (!ret) {
>     > >> +                  pr_err("Unable to find real path for %s\n", opts.root);
>     > >> +                  return -1;
>     > >> +          }
>     > >> +
>     > >>            /* moving a mount residing under a shared mount is invalid. */
>     > >> -          mi = mount_resolve_path(ns.mnt.mntinfo_tree, opts.root);
>     > >> +          mi = mount_resolve_path(ns.mnt.mntinfo_tree, path);
>     > >>            if (mi == NULL) {
>     > >>                    pr_err("Unable to find mount point for %s\n", opts.root);
>     > >>                    return -1;
>     > >> --
>     > >> 2.7.3
>     > >>
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>     > > .
>     > >
>     >
> 
> 
> 
> 
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