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Commit 4335d092 authored by Moger, Babu's avatar Moger, Babu Committed by James Bottomley
Browse files

[SCSI] scsi_dh_alua: Inroduce the set_params interface scsi_dh_alua handler 



Handler expects only one parameter to set the flag ALUA_OPTIMIZE_STPG.
This flag is used to optimize the STPG behaviour. There is no change in
behaviour by default.

For example, to set the flag pass the following parameters from multipath.conf
hardware_handler        "2 alua 1"

Signed-off-by: default avatarBabu Moger <babu.moger@netapp.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 8643b32f

drivers/scsi/device_handler/scsi_dh_alua.c

+36 −0
Original line number Diff line number Diff line
@@ -55,11 +55,15 @@ 
#define ALUA_FAILOVER_TIMEOUT		(60 * HZ)

#define ALUA_FAILOVER_RETRIES		5



/* flags passed from user level */

#define ALUA_OPTIMIZE_STPG		1



struct alua_dh_data {

	int			group_id;

	int			rel_port;

	int			tpgs;

	int			state;

	unsigned		flags; /* used for optimizing STPG */

	unsigned char		inq[ALUA_INQUIRY_SIZE];

	unsigned char		*buff;

	int			bufflen;
@@ -621,6 +625,37 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) 
out:

	return err;

}

/*

 * alua_set_params - set/unset the optimize flag

 * @sdev: device on the path to be activated

 * params - parameters in the following format

 *      "no_of_params\0param1\0param2\0param3\0...\0"

 * For example, to set the flag pass the following parameters

 * from multipath.conf

 *     hardware_handler        "2 alua 1"

 */

static int alua_set_params(struct scsi_device *sdev, const char *params)

{

	struct alua_dh_data *h = get_alua_data(sdev);

	unsigned int optimize = 0, argc;

	const char *p = params;

	int result = SCSI_DH_OK;



	if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))

		return -EINVAL;



	while (*p++)

		;

	if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))

		return -EINVAL;



	if (optimize)

		h->flags |= ALUA_OPTIMIZE_STPG;

	else

		h->flags &= ~ALUA_OPTIMIZE_STPG;



	return result;

}



/*

 * alua_activate - activate a path
@@ -698,6 +733,7 @@ static struct scsi_device_handler alua_dh = { 
	.prep_fn = alua_prep_fn,

	.check_sense = alua_check_sense,

	.activate = alua_activate,

	.set_params = alua_set_params,

	.match = alua_match,

};