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authorMoger, Babu <Babu.Moger@netapp.com>2012-03-27 20:55:49 +0000
committerJames Bottomley <JBottomley@Parallels.com>2012-04-23 19:28:07 +0100
commit4335d092a1f28e17c5bafa6170bbf9599ca29c6a (patch)
treeb72bf29f5c241ef53a342dd9c926edd0b1b3074a /drivers/scsi/device_handler
parent8643b32f275466f0b706e829150b7db49c11419c (diff)
downloadlinux-4335d092a1f28e17c5bafa6170bbf9599ca29c6a.tar.bz2
[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>
Diffstat (limited to 'drivers/scsi/device_handler')
-rw-r--r--drivers/scsi/device_handler/scsi_dh_alua.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 04c5cea47a22..506206ae5755 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -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,
};