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

[Andrew Vagin]

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>
> ---
>  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.

> +		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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