[lxc-devel] lxc-clone outputs some logs

[Serge Hallyn]

Quoting KATOH Yasufumi (karma at jazz.email.ne.jp):
> Hi,
> 
> >>> On Thu, 30 Oct 2014 14:35:16 +0000
>     in message   "Re: [lxc-devel] lxc-clone outputs some logs"
>                   Serge Hallyn-san wrote:
> 
> > > > > After applying commit edf7734 "overlay and aufs clone_paths: be more
> > > > > robust", clone was completed successfully but lxc-clone on unpriv env
> > > > > is now output the following log:
> > > 
> > > > >   $ lxc-clone -o ct02 -n test -s -B overlayfs
> > > > >   lxc_container: conf.c: chown_mapped_root: 3649 Error stat /home/karma/.local/share/lxc/test/delta0
> > > > >   Created container test as snapshot of ct02
> > > > >   lxc_container: lxccontainer.c: copy_file: 2303 copy destination /home/karma/.local/share/lxc/test/lxc_rdepends exists
> > > > >   Created container test as snapshot of ct02
> > > 
> > > > ct02 is the cloned container with overlayfs.
> > > 
> > > I find out other problem. After applying that patch, in part of the
> > > beginning of overlayfs_clonepath function, new->dest variable is,
> > > for example:
> > >   "overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local/share/lxc/ct02/delta0"
> > > 
> > > So, as the result, run "mkdir_p(new->dest, 0755)", and create dir in
> > > current dir.
> > > 
> > > $ lxc-clone -o ct02 -n test -s -B overlayfs
> > > lxc_container: conf.c: chown_mapped_root: 3649 Error stat /home/karma/.local/share/lxc/test/delta0
> > > Created container test as snapshot of ct02
> > > lxc_container: lxccontainer.c: copy_file: 2303 copy destination /home/karma/.local/share/lxc/test/lxc_rdepends exists
> > > Created container test as snapshot of ct02
> > > $ find overlayfs\:/
> > > overlayfs:/
> > > overlayfs:/home
> > > overlayfs:/home/karma
> > > overlayfs:/home/karma/.local
> > > overlayfs:/home/karma/.local/share
> > > overlayfs:/home/karma/.local/share/lxc
> > > overlayfs:/home/karma/.local/share/lxc/ct01
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local/share
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local/share/lxc
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local/share/lxc/test
> > > overlayfs:/home/karma/.local/share/lxc/ct01/rootfs:/home/karma/.local/share/lxc/test/delta0
> 
> > Sorry, I'm not really following, and I guess I haven't been using overlayfs
> > clones much lately.  Do you how to fix it, and can you send a patch?
> 
> This problem is also caused when clone by aufs. (between aufs/olfs)
> 
> This problem is caused by passing invalid argument as bdev *new to
> (aufs|overlayfs)_clonepath.
> 
> I don't understand your patch edf7734 well. But how about revert a
> part of the commit edf7734? as following:
> 

Hm.  I see.  Ok, then we will have to fix the 'dir' case by actually
creating des if it doesn't exist.  Else in the case of

lxc-clone -o x1 -n x2

where x1's config has

lxc.rootfs = /var/lib/lxc/x1/x

the clone will fail again, because dir_mount() tries to mount on a
nonexistant directory.  Can you send the patch to fix that?

> ---
>  src/lxc/bdev.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lxc/bdev.c b/src/lxc/bdev.c
> index ae5c77c..a9f100c 100644
> --- a/src/lxc/bdev.c
> +++ b/src/lxc/bdev.c
> @@ -3338,12 +3338,28 @@ struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
>                 return NULL;
>         }
>  
> -       orig = bdev_init(c0->lxc_conf, src, src, NULL);
> +       orig = bdev_init(c0->lxc_conf, src, NULL, NULL);
>         if (!orig) {
>                 ERROR("failed to detect blockdev type for %s", src);
>                 return NULL;
>         }
>  
> +       if (!orig->dest) {
> +               int ret;
> +               orig->dest = malloc(MAXPATHLEN);
> +               if (!orig->dest) {
> +                       ERROR("out of memory");
> +                       bdev_put(orig);
> +                       return NULL;
> +               }
> +               ret = snprintf(orig->dest, MAXPATHLEN, "%s/%s/rootfs", oldpath, oldname);
> +               if (ret < 0 || ret >= MAXPATHLEN) {
> +                       ERROR("rootfs path too long");
> +                       bdev_put(orig);
> +                       return NULL;
> +               }
> +       }
> +
>         /*
>          * special case for snapshot - if caller requested maybe_snapshot and
>          * keepbdevtype and backing store is directory, then proceed with a copy
> -- 
> 2.1.1
> 
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