Re: [ndctl PATCH 3/3] ndctl/namespace: add a --continue option to create namespaces greedily

[jane.chu@oracle.com]

Hi, Vishal,


On 8/28/19 5:17 PM, Vishal Verma wrote:
> Add a --continue option to ndctl-create-namespaces to allow the creation
> of as many namespaces as possible, that meet the given filter
> restrictions.
> 
> The creation loop will be aborted if a failure is encountered at any
> point.

Just wondering what is the motivation behind providing this option?

thanks!
-jane

> 
> Link: https://github.com/pmem/ndctl/issues/106
> Reported-by: Steve Scargal <steve.scargall@intel.com>
> Cc: Jeff Moyer <jmoyer@redhat.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>   .../ndctl/ndctl-create-namespace.txt          |  7 ++++++
>   ndctl/namespace.c                             | 25 +++++++++++++++----
>   2 files changed, 27 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/ndctl/ndctl-create-namespace.txt b/Documentation/ndctl/ndctl-create-namespace.txt
> index c9ae27c..55a8581 100644
> --- a/Documentation/ndctl/ndctl-create-namespace.txt
> +++ b/Documentation/ndctl/ndctl-create-namespace.txt
> @@ -215,6 +215,13 @@ include::xable-region-options.txt[]
>   --bus=::
>   include::xable-bus-options.txt[]
>   
> +-c::
> +--continue::
> +	Do not stop after creating one namespace. Instead, greedily create as
> +	many namespaces as possible within the given --bus and --region filter
> +	restrictions. This will abort if any creation attempt results in an
> +	error.
> +
>   include::../copyright.txt[]
>   
>   SEE ALSO
> diff --git a/ndctl/namespace.c b/ndctl/namespace.c
> index af20a42..8d6b249 100644
> --- a/ndctl/namespace.c
> +++ b/ndctl/namespace.c
> @@ -41,6 +41,7 @@ static struct parameters {
>   	bool do_scan;
>   	bool mode_default;
>   	bool autolabel;
> +	bool greedy;
>   	const char *bus;
>   	const char *map;
>   	const char *type;
> @@ -114,7 +115,9 @@ OPT_STRING('t', "type", &param.type, "type", \
>   OPT_STRING('a', "align", &param.align, "align", \
>   	"specify the namespace alignment in bytes (default: 2M)"), \
>   OPT_BOOLEAN('f', "force", &force, "reconfigure namespace even if currently active"), \
> -OPT_BOOLEAN('L', "autolabel", &param.autolabel, "automatically initialize labels")
> +OPT_BOOLEAN('L', "autolabel", &param.autolabel, "automatically initialize labels"), \
> +OPT_BOOLEAN('c', "continue", &param.greedy, \
> +	"continue creating namespaces as long as the filter criteria are met")
>   
>   #define CHECK_OPTIONS() \
>   OPT_BOOLEAN('R', "repair", &repair, "perform metadata repairs"), \
> @@ -1365,8 +1368,11 @@ static int do_xaction_namespace(const char *namespace,
>   				rc = namespace_create(region);
>   				if (rc == -EAGAIN)
>   					continue;
> -				if (rc == 0)
> -					*processed = 1;
> +				if (rc == 0) {
> +					(*processed)++;
> +					if (param.greedy)
> +						continue;
> +				}
>   				return rc;
>   			}
>   			ndctl_namespace_foreach_safe(region, ndns, _n) {
> @@ -1427,9 +1433,15 @@ static int do_xaction_namespace(const char *namespace,
>   		/*
>   		 * Namespace creation searched through all candidate
>   		 * regions and all of them said "nope, I don't have
> -		 * enough capacity", so report -ENOSPC
> +		 * enough capacity", so report -ENOSPC. Except during
> +		 * greedy namespace creation using --continue as we
> +		 * may have created some namespaces already, and the
> +		 * last one in the region search may preexist.
>   		 */
> -		rc = -ENOSPC;
> +		if (param.greedy && (*processed) > 0)
> +			rc = 0;
> +		else
> +			rc = -ENOSPC;
>   	}
>   
>   	return rc;
> @@ -1487,6 +1499,9 @@ int cmd_create_namespace(int argc, const char **argv, struct ndctl_ctx *ctx)
>   		rc = do_xaction_namespace(NULL, ACTION_CREATE, ctx, &created);
>   	}
>   
> +	if (param.greedy)
> +		fprintf(stderr, "created %d namespace%s\n", created,
> +			created == 1 ? "" : "s");
>   	if (rc < 0 || (!namespace && created < 1)) {
>   		fprintf(stderr, "failed to %s namespace: %s\n", namespace
>   				? "reconfigure" : "create", strerror(-rc));
> 
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