Re: [PATCH 15/17] Monitor: more accurate size check when looking for spares

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

On 10/29/2010 7:26 AM, Czarnowska, Anna wrote:
>  From 1e6de2b744115224be88da674e633c33934e5cb6 Mon Sep 17 00:00:00 2001
> From: Anna Czarnowska<anna.czarnowska@intel.com>
> Date: Wed, 27 Oct 2010 12:06:42 +0100
> Subject: [PATCH 15/17] Monitor: more accurate size check when looking for spares
>
> Signed-off-by: Anna Czarnowska<anna.czarnowska@intel.com>
> ---
>   Monitor.c     |   23 ++++++++++++++++++++++-
>   mdadm.h       |    1 +
>   super-intel.c |   32 ++++++++++++++++++++++++++++++++
>   3 files changed, 55 insertions(+), 1 deletions(-)
>
> diff --git a/Monitor.c b/Monitor.c
> index aa2856e..efe36eb 100644
> --- a/Monitor.c
> +++ b/Monitor.c
> @@ -766,6 +766,27 @@ unsigned long long min_active_disk_size_in_array(struct state *st)
>   	return min;
>   }
>
> +unsigned long long min_spare_size_required(struct state *st,
> +					   struct supertype *sty)
> +{
> +	int fd;
> +	unsigned long long rv = 0;
> +
> +	if (!sty)
> +		return rv;
> +	if (sty->ss->min_acceptable_spare_size) {
> +		fd = open(st->devname, O_RDONLY);
> +		if (fd<  0)
> +			return 0;
> +		sty->ss->load_super(sty, fd, st->devname);
> +		close(fd);
> +		rv = sty->ss->min_acceptable_spare_size(sty);
> +		sty->ss->free_super(sty);
> +	} else
> +		rv = min_active_disk_size_in_array(st);
> +	return rv;
> +}
> +
>   struct state *get_parent(struct state *st)
>   {
>   	if (is_external(st->metadata_version))
> @@ -892,7 +913,7 @@ static void spare_sharing(struct state *statelist, char *mailaddr,
>   			dprintf("no sra for device: %s\n", stp->devname);
>   			continue;
>   		}
> -		min_size = min_active_disk_size_in_array(st);
> +		min_size = min_spare_size_required(stp, super);
>   		if (min_size == 0)
>   			continue;
>   		for (i = 0; i<  stp->total; i++)
> diff --git a/mdadm.h b/mdadm.h
> index 4ef3ee5..7047fdf 100644
> --- a/mdadm.h
> +++ b/mdadm.h
> @@ -605,6 +605,7 @@ extern struct superswitch {
>   	int (*load_super)(struct supertype *st, int fd, char *devname);
>   	struct supertype * (*match_metadata_desc)(char *arg);
>   	__u64 (*avail_size)(struct supertype *st, __u64 size);
> +	unsigned long long (*min_acceptable_spare_size)(struct supertype *st);
>   	int (*add_internal_bitmap)(struct supertype *st, int *chunkp,
>   				   int delay, int write_behind,
>   				   unsigned long long size, int may_change, int major);
> diff --git a/super-intel.c b/super-intel.c
> index bcc202e..77c9d7f 100644
> --- a/super-intel.c
> +++ b/super-intel.c
> @@ -646,6 +646,37 @@ static int is_failed(struct imsm_disk *disk)
>   	return (disk->status&  FAILED_DISK) == FAILED_DISK;
>   }
>
> +/* Return minimum size of a spare that can be used in this array*/
> +static unsigned long long min_acceptable_spare_size_imsm(struct supertype *st)
> +{
> +	struct intel_super *super = st->sb;
> +	struct dl *dl;
> +	struct extent *e;
> +	int i;
> +	unsigned long long rv = 0;
> +
> +	if (!super)
> +		return rv;
> +	/* find first active disk in array */
> +	dl = super->disks;
> +	while (dl&&  (is_failed(&dl->disk) || dl->index == -1))
> +		dl = dl->next;
> +	if (!dl)
> +		return rv;
> +	/* find last lba used by subarrays */
> +	e = get_extents(super, dl);
> +	if (!e)
> +		return rv;
> +	for (i = 0; e[i].size; i++)
> +		continue;
> +	if (i>  0)
> +		rv = e[i-1].start + e[i-1].size;
> +	free(e);
> +	/* add the amount of space needed for metadata */
> +	rv = rv + MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS;
> +	return rv * 512;
> +}
> +
>   #ifndef MDASSEMBLE
>   static __u64 blocks_per_migr_unit(struct imsm_dev *dev);
>
> @@ -5629,6 +5660,7 @@ struct superswitch super_imsm = {
>   	.update_super	= update_super_imsm,
>
>   	.avail_size	= avail_size_imsm,
> +	.min_acceptable_spare_size = min_acceptable_spare_size_imsm,

Neil wondered if we can repurpose validate_geometry for this case?  It 
is already charged with checking if a disk is suitable to be added to an 
array.