NVMeoF multi-path setup

[mlin@kernel.org (Ming Lin)]

On Thu, 2016-06-30@14:08 -0700, Ming Lin wrote:
> Hi Mike,
> 
> I'm trying to test NVMeoF multi-path.
> 
> root at host:~# lsmod |grep dm_multipath
> dm_multipath           24576  0
> root at host:~# ps aux |grep multipath
> root     13183  0.0  0.1 238452  4972 ?        SLl  13:41   0:00
> /sbin/multipathd
> 
> I have nvme0 and nvme1 that are 2 paths to the same NVMe subsystem.
> 
> root at host:/sys/class/nvme# grep . nvme*/address
> nvme0/address:traddr=192.168.3.2,trsvcid=1023
> nvme1/address:traddr=192.168.2.2,trsvcid=1023
> 
> root at host:/sys/class/nvme# grep . nvme*/subsysnqn
> nvme0/subsysnqn:nqn.testiqn
> nvme1/subsysnqn:nqn.testiqn
> 
> root at host:~# /lib/udev/scsi_id --export --whitelisted -d /dev/nvme1n1
> ID_SCSI=1
> ID_VENDOR=NVMe
> ID_VENDOR_ENC=NVMe\x20\x20\x20\x20
> ID_MODEL=Linux
> ID_MODEL_ENC=Linux
> ID_REVISION=0-rc
> ID_TYPE=disk
> ID_SERIAL=SNVMe_Linux
> ID_SERIAL_SHORT=
> ID_SCSI_SERIAL=1122334455667788
> 
> root at host:~# /lib/udev/scsi_id --export --whitelisted -d /dev/nvme0n1
> ID_SCSI=1
> ID_VENDOR=NVMe
> ID_VENDOR_ENC=NVMe\x20\x20\x20\x20
> ID_MODEL=Linux
> ID_MODEL_ENC=Linux
> ID_REVISION=0-rc
> ID_TYPE=disk
> ID_SERIAL=SNVMe_Linux
> ID_SERIAL_SHORT=
> ID_SCSI_SERIAL=1122334455667788
> 
> But seems multipathd didn't recognize these 2 devices.
> 
> What else I'm missing?

There are two problems:

1. there is no "/block/" in the path

/sys/devices/virtual/nvme-fabrics/block/nvme0/nvme0n1

2. nvme was blacklisted.

I added below quick hack to just make it work.

root at host:~# cat /proc/partitions

 259        0  937692504 nvme0n1
 252        0  937692504 dm-0
 259        1  937692504 nvme1n1

diff --git a/libmultipath/blacklist.c b/libmultipath/blacklist.c
index 2400eda..a143383 100644
--- a/libmultipath/blacklist.c
+++ b/libmultipath/blacklist.c
@@ -190,9 +190,11 @@ setup_default_blist (struct config * conf)
 	if (store_ble(conf->blist_devnode, str, ORIGIN_DEFAULT))
 		return 1;
 
+#if 0
 	str = STRDUP("^nvme.*");
 	if (!str)
 		return 1;
+#endif
 	if (store_ble(conf->blist_devnode, str, ORIGIN_DEFAULT))
 		return 1;
 
diff --git a/multipathd/main.c b/multipathd/main.c
index c0ca571..1364070 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -1012,6 +1012,7 @@ uxsock_trigger (char * str, char ** reply, int * len, void * trigger_data)
 static int
 uev_discard(char * devpath)
 {
+#if 0
 	char *tmp;
 	char a[11], b[11];
 
@@ -1028,6 +1029,7 @@ uev_discard(char * devpath)
 		condlog(4, "discard event on %s", devpath);
 		return 1;
 	}
+#endif
 	return 0;
 }