[lvm-devel] [PATCH 4/6] Add vg_read_error and vg_might_exist.

[Dave Wysochanski]

On Thu, 2009-01-15 at 11:34 +0100, Petr Rockai wrote:
> Thu Jan 15 10:55:43 CET 2009  Petr Rockai <me at mornfall.net>
>   * Add vg_read_error and vg_might_exist.
> diff -rN -u -p old-temp.23590/lib/metadata/metadata.c new-temp.23590/lib/metadata/metadata.c
> --- old-temp.23590/lib/metadata/metadata.c	2009-01-15 11:27:12.171749221 +0100
> +++ new-temp.23590/lib/metadata/metadata.c	2009-01-15 11:27:12.223751222 +0100
> @@ -2663,6 +2663,40 @@ vg_t *vg_read_for_update(struct cmd_cont
>  }
>  
>  /*
> + * Check whether a vg_read (or vg_read_for_update) operation resulted in an
> + * error, or completed successfully. If EXISTENCE_CHECK has been given to
> + * vg_read, we do not consider nonexistence of the volume group an error. The
> + * caller is responsible for using vg_might_exist:
> + * - !vg_read_error(vg) && vg_might_exist(vg) -> vg is a valid handle
> + * - vg_read_error(vg) && vg_might_exist(vg) -> vg is not valid, but the VG in
> + *   question probably exists, it just cannot be opened (consult vg_read_error
> + *   return code for reason).
> + * - !vg_read_error(vg) && !vg_might_exist(vg) -> the VG does not exist
> + * - vg_read_error(vg) && !vg_might_exist(vg) -> cannot happen
> + */
> +uint32_t vg_read_error(vg_t *vg)
> +{
> +	if (!vg)
> +		return FAILED_ALLOCATION;
> +	if (vg->read_failed & EXISTENCE_CHECK)
> +		return vg->read_failed & ~(EXISTENCE_CHECK | FAILED_NOTFOUND);
> +	return vg->read_failed;
> +}
> +
> +/*
> + * Returns true if the volume group already exists. If unsure, it will return
> + * true (it might exist, but we are not sure, as the read failed for some other
> + * reason).
> + */
> +uint32_t vg_might_exist(vg_t *vg) {
> +	if (!vg)
> +		return 1;
> +	if (vg->read_failed == (FAILED_NOTFOUND | EXISTENCE_CHECK))
> +		return 0;
> +	return 1;
> +}
> +
> +/*
>   * Gets/Sets for external LVM library
>   */
>  struct id pv_id(const pv_t *pv)
> diff -rN -u -p old-temp.23590/lib/metadata/metadata-exported.h new-temp.23590/lib/metadata/metadata-exported.h
> --- old-temp.23590/lib/metadata/metadata-exported.h	2009-01-15 11:27:12.171749221 +0100
> +++ new-temp.23590/lib/metadata/metadata-exported.h	2009-01-15 11:27:12.223751222 +0100
> @@ -399,6 +399,10 @@ vg_t *vg_read(struct cmd_context *cmd, c
>  vg_t *vg_read_for_update(struct cmd_context *cmd, const char *vg_name,
>                           const char *vgid, uint32_t flags);
>  
> +/* Queries on a (possibly error-indicating) VG handle. */
> +uint32_t vg_read_error(vg_t *vg);
> +uint32_t vg_might_exist(vg_t *vg);
> +
>  /* pe_start and pe_end relate to any existing data so that new metadata
>  * areas can avoid overlap */
>  pv_t *pv_create(const struct cmd_context *cmd,
> 

This second hunk doesn't apply, probably because this patch is out of
sequence from the original sequence of 11 (comes after the
vg_read_for_update patch in this sequence).