[dm-devel] [2.6.22-rc1 PATCH] dm-hp-sw: HP Active/Passive hardware handler baseline

[Mike Christie]

Dave Wysochanski wrote:
> +#include <scsi/scsi.h>
> +#include <scsi/scsi_cmnd.h>
> +#include <scsi/scsi_dbg.h>
> +#include <scsi/scsi_device.h>
> +#include <scsi/scsi_host.h>
> +#include <scsi/scsi_transport_fc.h>
> +#include <linux/list.h>
> +#include <linux/types.h>

you should do linux includes then scsi ones. Do you even need the fc,
host or cmnd includes?

> +
> +#include "dm.h"
> +#include "dm-hw-handler.h"
> +
> +#define DM_MSG_PREFIX "multipath hp"
> +
> +struct hp_sw_context {
> +	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
> +};
> +
> +
> +/**
> + * hp_sw_end_io - Completion handler for HP path activation.
> + * @req: failover request
> + * @error: scsi-ml error
> + *
> + *  Check sense data, free request structure, and notify dm that
> + *  pg initialization has completed.
> + *
> + * Context: scsi-ml softirq
> + *
> + * Possible optimizations
> + * 1. Actually check sense data for retryable error (e.g. NOT_READY)
> + */
> +static void hp_sw_end_io(struct request *req, int error)
> +{
> +	struct dm_path *path = req->end_io_data;
> +	unsigned err_flags;
> +
> +	if (!error) {
> +		err_flags = 0;
> +		DMDEBUG("hp_sw: path activation command on %s - success",
> +		       	path->dev->name);
> +	}
> +	else {

else should be on the same line as "{"


I also think we should handle the NOT_READY case that was reported before.


> +		DMWARN("hp_sw: path activation command on %s - error=0x%x",
> +		       path->dev->name, error);
> +		err_flags = MP_FAIL_PATH;
> +	}
> +
> +	req->end_io_data = NULL;
> +	__blk_put_request(req->q, req);
> +	dm_pg_init_complete(path, err_flags);
> +}
> +
> +/**
> + * hp_sw_get_request - Allocate an HP specific path activation request
> + * @path: path on which request will be sent (needed for request queue)
> + *
> + * The START command is used for path activation request.
> + * These arrays are controller-based failover, not LUN based.
> + * One START command issued to a single path will fail over all
> + * LUNs for the same controller.
> + *
> + * Possible optimizations
> + * 1. Make timeout configurable
> + * 2. Preallocate request
> + */
> +static struct request *hp_sw_get_request(struct dm_path *path)
> +{
> +	struct request *req=NULL;
> +	struct block_device *bdev = path->dev->bdev;
> +	struct request_queue *q = bdev_get_queue(bdev);
> +	struct hp_sw_context *h = path->hwhcontext;
> +
> +	req = blk_get_request(q, WRITE, GFP_ATOMIC);
> +	if (req == NULL)
> +		goto exit;
> +
> +	req->timeout = 60*HZ;
> +
> +	req->errors = 0;
> +	req->cmd_type = REQ_TYPE_BLOCK_PC;
> +	req->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
> +	req->end_io = hp_sw_end_io;
> +	req->end_io_data = path;
> +	req->sense = h->sense;
> +	memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE);
> +
> +	memset(&req->cmd, 0, BLK_MAX_CDB);
> +	req->cmd[0] = START_STOP;
> +	req->cmd[4] = 1;
> +	req->cmd_len = COMMAND_SIZE(req->cmd[0]);
> +exit:
> +	return req;
> +}
> +
> +/**
> + * hp_sw_pg_init - HP path activation implementation.
> + * @hwh: hardware handler specific data
> + * @bypassed: unused; is the path group bypassed? (see dm-mpath.c)
> + * @path: path to send initialization command
> + *
> + * Send an HP-specific path activation command on 'path'.
> + * Do not try to optimize in any way, just send the activation command.
> + * More than one path activation command may be sent to the same controller.
> + * This seems to work fine for basic failover support.
> + *
> + * Possible optimizations
> + * 1. Detect an in-progress activation request and avoid submitting another one
> + * 2. Model the controller and only send a single activation request at a time
> + * 3. Determine the state of a path before sending an activation request
> + *
> + * Context: kmpathd (see process_queued_ios() in dm-mpath.c)
> + */
> +static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed,
> +			  struct dm_path *path)
> +{
> +	struct request *req;
> +	struct hp_sw_context *h;
> +	unsigned err_flags;
> +
> +	path->hwhcontext = hwh->context;
> +	h = (struct hp_sw_context *) hwh->context;
> +

you do not need the case do you?