[CRIU] [PATCH 1/3] devmap: Introduce --device-map argument

[Pavel Emelyanov]

On 11/24/2015 01:12 PM, Cyrill Gorcunov wrote:
> We will need it when migration causes device numbers
> being changed and we need to proceed on new hardware.
> 
> At the moment this is needed for block devices.
> 
> https://jira.sw.ru/PSBM-41357
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>  Documentation/criu.txt |  4 ++++
>  crtools.c              | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/cr_options.h   |  2 ++
>  3 files changed, 54 insertions(+)
> 
> diff --git a/Documentation/criu.txt b/Documentation/criu.txt
> index 652706ee1aaa..c5dd4e56746e 100644
> --- a/Documentation/criu.txt
> +++ b/Documentation/criu.txt
> @@ -272,6 +272,10 @@ The '<mode>' may be one of below.
>      These flags enable external shared or slave mounts to be resolved
>      automatically when '*--ext-mount-map auto*' is passed.
>  
> +*--device-map* '<A>'*:*'<B>'[,'<C>'*:*'<D>']::
> +    Specify device mappings when migrating from one environment
> +    to another. Currently used for block devices.

So this is restore-only option, isn't it? Why not make it like --ext-mount-map
that would allow to replace one ID with another on dump too?

> +
>  *--auto-dedup*::
>      As soon as a page is restored it get punched out from image.
>  
> diff --git a/crtools.c b/crtools.c
> index d3812a18f4f0..8a51d205d4d5 100644
> --- a/crtools.c
> +++ b/crtools.c
> @@ -190,6 +190,48 @@ static size_t parse_size(char *optarg)
>  	return (size_t)atol(optarg);
>  }
>  
> +static int parse_device_map(struct cr_options *opts, char *optarg)
> +{
> +	size_t nr_alloc = 0, nr_devmap = 0;
> +	unsigned int *devmap = NULL;
> +	char *p = optarg;
> +	int ret = -1;
> +
> +	if (!optarg)
> +		return -EINVAL;
> +
> +	while (p) {
> +		unsigned int s, d;
> +		char *at;
> +
> +		if (sscanf(p, "%u:%u", &s, &d) != 2)
> +			goto out;
> +
> +		if (nr_alloc <= nr_devmap) {
> +			nr_alloc += 8;
> +			if (xrealloc_safe(&devmap, sizeof(*devmap) * nr_alloc))
> +				goto out;
> +		}
> +
> +		devmap[nr_devmap + 0] = s;
> +		devmap[nr_devmap + 1] = d;
> +
> +		nr_devmap += 2;
> +
> +		at = strchr(p, ',');
> +		p = at ? at + 1 : NULL;
> +	}
> +
> +	opts->devmap = devmap;
> +	opts->nr_devmap = nr_devmap;
> +
> +	devmap = NULL;
> +	ret = 0;
> +out:
> +	xfree(devmap);
> +	return ret;
> +}
> +
>  int main(int argc, char *argv[], char *envp[])
>  {
>  	pid_t pid = 0, tree_id = 0;
> @@ -253,6 +295,7 @@ int main(int argc, char *argv[], char *envp[])
>  		{ "freeze-cgroup",		required_argument,	0, 1068 },
>  		{ "ghost-limit",		required_argument,	0, 1069 },
>  		{ "irmap-scan-path",		required_argument,	0, 1070 },
> +		{ "device-map",			required_argument,	0, 1071 },
>  		{ },
>  	};
>  
> @@ -498,6 +541,10 @@ int main(int argc, char *argv[], char *envp[])
>  			if (irmap_scan_path_add(optarg))
>  				return -1;
>  			break;
> +		case 1071:
> +			if (parse_device_map(&opts, optarg))
> +				goto bad_arg;
> +			break;
>  		case 'M':
>  			{
>  				char *aux;
> @@ -747,6 +794,7 @@ usage:
>  "  --enable-fs FSNAMES   a comma separated list of filesystem names or \"all\".\n"
>  "                        force criu to (try to) dump/restore these filesystem's\n"
>  "                        mountpoints even if fs is not supported.\n"
> +"  --device-map a:b[,..] a comma separated colon splitted device mapping pairs.\n"
>  "\n"
>  "* Logging:\n"
>  "  -o|--log-file FILE    log file name\n"
> diff --git a/include/cr_options.h b/include/cr_options.h
> index eac7283a4821..1451b386cce1 100644
> --- a/include/cr_options.h
> +++ b/include/cr_options.h
> @@ -95,6 +95,8 @@ struct cr_options {
>  	bool			overlayfs;
>  	size_t			ghost_limit;
>  	struct list_head	irmap_scan_paths;
> +	unsigned int		*devmap;
> +	size_t			nr_devmap;
>  };
>  
>  extern struct cr_options opts;
>