Re: [PATCH 13/13] External reshape (step 2): Freeze container

[Neil Brown <neilb@suse.de>]

On Thu, 18 Nov 2010 10:23:08 +0100
Krzysztof Wojcik <krzysztof.wojcik@intel.com> wrote:

> From: Dan Williams <dan.j.williams@intel.com>
> 
> When growing the number of raid disks the reshape process will promote
> container-spares to subarray-spares (later the kernel promotes them to
> subarray-members in raid5_start_reshape()).  The automatic spare
> promotion that mdmon performs upon seeing a degraded array must be
> disabled until the reshape process has been initiated.  Otherwise, mdmon
> may start a rebuild before the reshape parameters can be specified.
> 
> In the external case we arrange for the monitor to be blocked, and turn off the safemode delay.
> Mdmon is updated to check sync_action is not frozen before initiating
> recovery.  This introduces a need to check which version of mdmon is
> running to be sure it honors the expected semantics.  Extend
> ping_monitor() to report the version of mdmon.  This also permits
> discrimination of known buggy mdmon implementations in the future.
> Note, it's not enough to know the current version of mdadm because the
> mdmon instance may have originated from the initrd, so there is no
> guaratee that mdadm and mdmon versions are synchronized.

I have applied this, and all the others that I didn't raise explicit issues
with (which I think was only 
    [PATCH 07/13] Grow: add missing raid4 geometries to geo_map()

and I have pushed out a new devel-3.2

Thanks,
NeilBrown


> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  Grow.c |   88 ++++++++++++++++++++++++++++++++++++++++++++++++++--------------
>  1 files changed, 69 insertions(+), 19 deletions(-)
> 
> diff --git a/Grow.c b/Grow.c
> index 59032ef..4139265 100644
> --- a/Grow.c
> +++ b/Grow.c
> @@ -432,29 +432,78 @@ static int child_same_size(int afd, struct mdinfo *sra, unsigned long blocks,
>  			   int disks, int chunk, int level, int layout, int data,
>  			   int dests, int *destfd, unsigned long long *destoffsets);
>  
> -static int freeze_array(struct mdinfo *sra)
> +static int freeze_container(struct supertype *st)
>  {
> -	/* Try to freeze resync on this array.
> +	int container_dev = st->subarray[0] ? st->container_dev : st->devnum;
> +	char *container = devnum2devname(container_dev);
> +
> +	if (!container) {
> +		fprintf(stderr, Name
> +			": could not determine container name, freeze aborted\n");
> +		return -2;
> +	}
> +
> +	if (block_monitor(container, 1)) {
> +		fprintf(stderr, Name ": failed to freeze container\n");
> +		return -2;
> +	}
> +
> +	return 1;
> +}
> +
> +static void unfreeze_container(struct supertype *st)
> +{
> +	int container_dev = st->subarray[0] ? st->container_dev : st->devnum;
> +	char *container = devnum2devname(container_dev);
> +
> +	if (!container) {
> +		fprintf(stderr, Name
> +			": could not determine container name, unfreeze aborted\n");
> +		return;
> +	}
> +
> +	unblock_monitor(container, 1);
> +}
> +
> +static int freeze(struct supertype *st)
> +{
> +	/* Try to freeze resync/rebuild on this array/container.
>  	 * Return -1 if the array is busy,
> +	 * return -2 container cannot be frozen,
>  	 * return 0 if this kernel doesn't support 'frozen'
>  	 * return 1 if it worked.
>  	 */
> -	char buf[20];
> -	if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0)
> -		return 0;
> -	if (strcmp(buf, "idle\n") != 0 &&
> -	    strcmp(buf, "frozen\n") != 0)
> -		return -1;
> -	if (sysfs_set_str(sra, NULL, "sync_action", "frozen") < 0)
> -		return 0;
> -	return 1;
> +	if (st->ss->external)
> +		return freeze_container(st);
> +	else {
> +		struct mdinfo *sra = sysfs_read(-1, st->devnum, GET_VERSION);
> +		int err;
> +
> +		if (!sra)
> +			return -1;
> +		err = sysfs_freeze_array(sra);
> +		sysfs_free(sra);
> +		return err;
> +	}
>  }
>  
> -static void unfreeze_array(struct mdinfo *sra, int frozen)
> +static void unfreeze(struct supertype *st, int frozen)
>  {
>  	/* If 'frozen' is 1, unfreeze the array */
> -	if (frozen > 0)
> -		sysfs_set_str(sra, NULL, "sync_action", "idle");
> +	if (frozen <= 0)
> +		return;
> +
> +	if (st->ss->external)
> +		return unfreeze_container(st);
> +	else {
> +		struct mdinfo *sra = sysfs_read(-1, st->devnum, GET_VERSION);
> +
> +		if (sra)
> +			sysfs_set_str(sra, NULL, "sync_action", "idle");
> +		else
> +			fprintf(stderr, Name ": failed to unfreeze array\n");
> +		sysfs_free(sra);
> +	}
>  }
>  
>  static void wait_reshape(struct mdinfo *sra)
> @@ -818,19 +867,21 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
>  			array.level = LEVEL_CONTAINER;
>  			sra->array.level = LEVEL_CONTAINER;
>  		}
> -		frozen = freeze_array(sra);
>  	} else {
>  		fprintf(stderr, Name ": failed to read sysfs parameters for %s\n",
>  			devname);
>  		return 1;
>  	}
> -	if (frozen < 0) {
> +	frozen = freeze(st);
> +	if (frozen < -1) {
> +		/* freeze() already spewed the reason */
> +		return 1;
> +	} else if (frozen < 0) {
>  		fprintf(stderr, Name ": %s is performing resync/recovery and cannot"
>  			" be reshaped\n", devname);
>  		return 1;
>  	}
>  
> -
>  	/* ========= set size =============== */
>  	if (size >= 0 && (size == 0 || size != array.size)) {
>  		long long orig_size = array.size;
> @@ -1611,8 +1662,7 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
>  		if (c && sysfs_set_str(sra, NULL, "level", c) == 0)
>  			fprintf(stderr, Name ": aborting level change\n");
>  	}
> -	if (sra)
> -		unfreeze_array(sra, frozen);
> +	unfreeze(st, frozen);
>  	return rv;
>  }
>