[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: Babu Moger <babu.moger@netapp.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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@ -55,11 +55,15 @@
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#define ALUA_FAILOVER_TIMEOUT (60 * HZ)
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#define ALUA_FAILOVER_RETRIES 5
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/* flags passed from user level */
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#define ALUA_OPTIMIZE_STPG 1
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struct alua_dh_data {
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int group_id;
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int rel_port;
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int tpgs;
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int state;
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unsigned flags; /* used for optimizing STPG */
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unsigned char inq[ALUA_INQUIRY_SIZE];
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unsigned char *buff;
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int bufflen;
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@ -621,6 +625,37 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
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out:
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return err;
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}
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/*
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* alua_set_params - set/unset the optimize flag
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* @sdev: device on the path to be activated
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* params - parameters in the following format
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* "no_of_params\0param1\0param2\0param3\0...\0"
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* For example, to set the flag pass the following parameters
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* from multipath.conf
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* hardware_handler "2 alua 1"
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*/
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static int alua_set_params(struct scsi_device *sdev, const char *params)
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{
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struct alua_dh_data *h = get_alua_data(sdev);
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unsigned int optimize = 0, argc;
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const char *p = params;
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int result = SCSI_DH_OK;
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if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
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return -EINVAL;
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while (*p++)
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;
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if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
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return -EINVAL;
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if (optimize)
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h->flags |= ALUA_OPTIMIZE_STPG;
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else
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h->flags &= ~ALUA_OPTIMIZE_STPG;
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return result;
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}
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/*
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* alua_activate - activate a path
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@ -698,6 +733,7 @@ static struct scsi_device_handler alua_dh = {
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.prep_fn = alua_prep_fn,
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.check_sense = alua_check_sense,
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.activate = alua_activate,
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.set_params = alua_set_params,
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.match = alua_match,
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};
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