util: Introduce virStorageFileGetNPIVKey

The vHBA/NPIV LUNs created via the udev processing of the
VPORT_CREATE command end up using the same serial value
as seen/generated by the /lib/udev/scsi_id as returned
during virStorageFileGetSCSIKey. Therefore, in order to
generate a unique enough key to be used when adding the
LUN as a volume during virStoragePoolObjAddVol a more
unique key needs to be generated for an NPIV volume.

The problem is illustrated by the following example, where
scsi_host5 is a vHBA used with the following LUNs:

$ lsscsi -tg
...
[5:0:4:0]    disk    fc:0x5006016844602198,0x101f00  /dev/sdh   /dev/sg23
[5:0:5:0]    disk    fc:0x5006016044602198,0x102000  /dev/sdi   /dev/sg24
...

Calling virStorageFileGetSCSIKey would return:

/lib/udev/scsi_id --device /dev/sdh --whitelisted --replace-whitespace /dev/sdh
350060160c460219850060160c4602198
/lib/udev/scsi_id --device /dev/sdh --whitelisted --replace-whitespace /dev/sdi
350060160c460219850060160c4602198

Note that althrough /dev/sdh and /dev/sdi are separate LUNs, they
end up with the same serial number used for the vol->key value.
When virStoragePoolFCRefreshThread calls virStoragePoolObjAddVol
the second LUN fails to be added with the following message
getting logged:

    virHashAddOrUpdateEntry:341 : internal error: Duplicate key

To resolve this, virStorageFileGetNPIVKey will use a similar call
sequence as virStorageFileGetSCSIKey, except that it will add the
"--export" option to the call. This results in more detailed output
which needs to be parsed in order to formulate a unique enough key
to be used. In order to be unique enough, the returned value will
concatenate the target port as returned in the "ID_TARGET_PORT"
field from the command to the "ID_SERIAL" value.

Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

src/libvirt_private.syms

@@ -2863,6 +2863,7 @@ virStorageFileGetMetadata;
 virStorageFileGetMetadataFromBuf;
 virStorageFileGetMetadataFromFD;
 virStorageFileGetMetadataInternal;
+virStorageFileGetNPIVKey;
 virStorageFileGetRelativeBackingPath;
 virStorageFileGetSCSIKey;
 virStorageFileGetUniqueIdentifier;

src/util/virstoragefile.c

@@ -1492,6 +1492,85 @@ int virStorageFileGetSCSIKey(const char *path,
 #endif
 
 
+#ifdef WITH_UDEV
+/* virStorageFileGetNPIVKey
+ * @path: Path to the NPIV device
+ * @key: Unique key to be returned
+ *
+ * Using a udev specific function, query the @path to get and return a
+ * unique @key for the caller to use. Unlike the GetSCSIKey method, an
+ * NPIV LUN is uniquely identified by its ID_TARGET_PORT value.
+ *
+ * Returns:
+ *     0 On success, with the @key filled in or @key=NULL if the
+ *       returned output string didn't have the data we need to
+ *       formulate a unique key value
+ *    -1 When WITH_UDEV is undefined and a system error is reported
+ *    -2 When WITH_UDEV is defined, but calling virCommandRun fails
+ */
+# define ID_SERIAL "ID_SERIAL="
+# define ID_TARGET_PORT "ID_TARGET_PORT="
+int
+virStorageFileGetNPIVKey(const char *path,
+                         char **key)
+{
+    int status;
+    VIR_AUTOFREE(char *) outbuf = NULL;
+    const char *serial;
+    const char *port;
+    virCommandPtr cmd = virCommandNewArgList("/lib/udev/scsi_id",
+                                             "--replace-whitespace",
+                                             "--whitelisted",
+                                             "--export",
+                                             "--device", path,
+                                             NULL
+                                             );
+    int ret = -2;
+
+    *key = NULL;
+
+    /* Run the program and capture its output */
+    virCommandSetOutputBuffer(cmd, &outbuf);
+    if (virCommandRun(cmd, &status) < 0)
+        goto cleanup;
+
+    /* Explicitly check status == 0, rather than passing NULL
+     * to virCommandRun because we don't want to raise an actual
+     * error in this scenario, just return a NULL key.
+     */
+    if (status == 0 && *outbuf &&
+        (serial = strstr(outbuf, ID_SERIAL)) &&
+        (port = strstr(outbuf, ID_TARGET_PORT))) {
+        char *tmp;
+
+        serial += strlen(ID_SERIAL);
+        port += strlen(ID_TARGET_PORT);
+
+        if ((tmp = strchr(serial, '\n')))
+            *tmp = '\0';
+
+        if ((tmp = strchr(port, '\n')))
+            *tmp = '\0';
+
+        if (*serial != '\0' && *port != '\0')
+            ignore_value(virAsprintf(key, "%s_PORT%s", serial, port));
+    }
+
+    ret = 0;
+
+ cleanup:
+    virCommandFree(cmd);
+
+    return ret;
+}
+#else
+int virStorageFileGetNPIVKey(const char *path,
+                             char **key ATTRIBUTE_UNUSED)
+{
+    return -1;
+}
+#endif
+
 /**
  * virStorageFileParseBackingStoreStr:
  * @str: backing store specifier string to parse

src/util/virstoragefile.h

@@ -392,6 +392,8 @@ int virStorageFileGetLVMKey(const char *path,
 int virStorageFileGetSCSIKey(const char *path,
                              char **key,
                              bool ignoreError);
+int virStorageFileGetNPIVKey(const char *path,
+                             char **key);
 
 void virStorageAuthDefFree(virStorageAuthDefPtr def);
 virStorageAuthDefPtr virStorageAuthDefCopy(const virStorageAuthDef *src);