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[SCSI] scsi_dh_alua: Inroduce the set_params interface scsi_dh_alua handler

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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: Babu Moger <babu.moger@netapp.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Moger, Babu 2012-03-27 20:55:49 +00:00 committed by James Bottomley
parent 8643b32f27
commit 4335d092a1
1 changed files with 36 additions and 0 deletions
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36
drivers/scsi/device_handler/scsi_dh_alua.c
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@ -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,
};