[libvirt] [PATCH] storage: More uniquely identify NPIV LUNs

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1657468

Commit be1bb6c95 changed the way volumes were stored from a forward
linked list to a hash table. In doing so, it required that each vol
object would have 3 unique values as keys into tables - key, name,
and path. Due to how vHBA/NPIV LUNs are created/used this resulted
in a failure to utilize all the LUN's found during processing.

The virStorageBackendSCSINewLun uses virStorageBackendSCSISerial
in order to read/return the unique serial number of the LUN to be
used as a key for the volume.

However, for NPIV based LUNs the logic results in usage of the
same serial value for each path to the LUN. For example,

$ lsscsi -tg
...
[4:0:3:13]   disk    fc:0x207800c0ffd79b2a0xeb02ef   /dev/sde   /dev/sg16
[4:0:4:0]    disk    fc:0x50060169446021980xeb1f00   /dev/sdf   /dev/sg17
[4:0:5:0]    disk    fc:0x50060161446021980xeb2000   /dev/sdg   /dev/sg18
...

/lib/udev/scsi_id --replace-whitespace --whitelisted --device /dev/sde
3600c0ff000d7a2965c603e5401000000
/lib/udev/scsi_id --replace-whitespace --whitelisted --device /dev/sdf
350060160c460219850060160c4602198
/lib/udev/scsi_id --replace-whitespace --whitelisted --device /dev/sdg
350060160c460219850060160c4602198

The /dev/sdf and /dev/sdg although separate LUNs would end up with the
same serial number used for the vol->key value. When attempting to add
the LUN via virStoragePoolObjAddVol, the hash table code will indicate
that we have a duplicate:

    virHashAddOrUpdateEntry:341 : internal error: Duplicate key

and thus the LUN is not added to the pool.

Digging deeper into the scsi_id output using the --export option one
will find that the only difference between the two luns is:

    ID_TARGET_PORT=1 for /dev/sdf
    ID_TARGET_PORT=2 for /dev/sdg

So, let's use the ID_TARGET_PORT string value along with the serial
to generate a more unique key using "@serial_PORT at target_port", where
@target_port is just the value of the ID_TARGET_PORT for the LUN.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/storage/storage_util.c | 61 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c
index a84ee5b600..d6d441c06d 100644
--- a/src/storage/storage_util.c
+++ b/src/storage/storage_util.c
@@ -3755,6 +3755,49 @@ virStorageBackendRefreshLocal(virStoragePoolObjPtr pool)
 }
 
 
+static char *
+virStorageBackendSCSITargetPort(const char *dev)
+{
+    char *target_port = NULL;
+    const char *id;
+#ifdef WITH_UDEV
+    virCommandPtr cmd = virCommandNewArgList(
+        "/lib/udev/scsi_id",
+        "--replace-whitespace",
+        "--whitelisted",
+        "--export",
+        "--device", dev,
+        NULL
+        );
+
+    /* Run the program and capture its output */
+    virCommandSetOutputBuffer(cmd, &target_port);
+    if (virCommandRun(cmd, NULL) < 0)
+        goto cleanup;
+#endif
+
+    if (target_port && STRNEQ(target_port, "") &&
+        (id = strstr(target_port, "ID_TARGET_PORT="))) {
+        char *nl = strchr(id, '\n');
+        if (nl)
+            *nl = '\0';
+        id = strrchr(id, '=');
+        memmove(target_port, id + 1, strlen(id));
+    } else {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unable to uniquely identify target port for '%s'"),
+                       dev);
+    }
+
+#ifdef WITH_UDEV
+ cleanup:
+    virCommandFree(cmd);
+#endif
+
+    return target_port;
+}
+
+
 static char *
 virStorageBackendSCSISerial(const char *dev)
 {
@@ -3813,6 +3856,8 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
     virStoragePoolDefPtr def = virStoragePoolObjGetDef(pool);
     virStorageVolDefPtr vol = NULL;
     char *devpath = NULL;
+    char *key = NULL;
+    char *target_port = NULL;
     int retval = -1;
 
     /* Check if the pool is using a stable target path. The call to
@@ -3877,9 +3922,21 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
                                                  VIR_STORAGE_VOL_READ_NOERROR)) < 0)
         goto cleanup;
 
-    if (!(vol->key = virStorageBackendSCSISerial(vol->target.path)))
+    if (!(key = virStorageBackendSCSISerial(vol->target.path)))
         goto cleanup;
 
+    if (def->source.adapter.type == VIR_STORAGE_ADAPTER_TYPE_FC_HOST &&
+        STRNEQ(key, vol->target.path)) {
+        /* NPIV based LUNs use the same "serial" key. In order to distinguish
+         * we need to append a port value */
+        if (!(target_port = virStorageBackendSCSITargetPort(vol->target.path)))
+            goto cleanup;
+        if (virAsprintf(&vol->key, "%s_PORT%s", key, target_port) < 0)
+            goto cleanup;
+    } else {
+        VIR_STEAL_PTR(vol->key, key);
+    }
+
     def->capacity += vol->target.capacity;
     def->allocation += vol->target.allocation;
 
@@ -3892,6 +3949,8 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
  cleanup:
     virStorageVolDefFree(vol);
     VIR_FREE(devpath);
+    VIR_FREE(target_port);
+    VIR_FREE(key);
     return retval;
 }
 
-- 
2.17.2