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

[Dan Williams <dan.j.williams@intel.com>]

On Wed, Aug 28, 2019 at 5:17 PM Vishal Verma <vishal.l.verma@intel.com> 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.
>
> 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

I like the "greedy" terminology here because it makes the option seem
a bit off-putting. "Do you really want to be greedy?"

> +       many namespaces as possible within the given --bus and --region filter
> +       restrictions. This will abort if any creation attempt results in an
> +       error.

Hmm, should "--continue --force" override that policy?

Otherwise this looks good to me.

> +
>  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));
> --
> 2.20.1
>
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