storage: Add new flag for libvirt_parthelper

https://bugzilla.redhat.com/show_bug.cgi?id=1265694

In order to be able to process disk storage pool's using a multipath
device to handle the partitions, libvirt_parthelper will need a way to
not automatically add a partition separator "p" to the generated device
name for each partition found. This is designed to mimic the multipath
features known as 'user_friendly_names' and custom 'alias' name.

If the part_separator attribute is set to "no", then generation of the
multipath partition name will not include the "p" partition separator
unless the source device path name ends with a number. The generated
partition names that get passed back to libvirt are processed in order
to find the device mapper multipath (dm-#) path device.

For example, device path "/dev/mapper/mpatha" would create partitions
"/dev/mapper/mpatha1", "/dev/mapper/mpatha2", etc. instead of
"/dev/mapper/mpathap1", "/dev/mapper/mpathap2", etc. If the device
path ends with a number "/dev/mapper/mpatha1", then the algorithm
to generate names "/dev/mapper/mpatha1p1", "/dev/mapper/mpatha1p2", etc.
would be utilized.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/storage/parthelper.c

@@ -10,7 +10,7 @@
  * in a reliable fashion if merely after a list of partitions & sizes,
  * though it is fine for creating partitions.
  *
- * Copyright (C) 2007-2008, 2010, 2013 Red Hat, Inc.
+ * Copyright (C) 2007-2008, 2010, 2013, 2016 Red Hat, Inc.
  * Copyright (C) 2007-2008 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -70,6 +70,7 @@ int main(int argc, char **argv)
     const char *path;
     char *canonical_path;
     const char *partsep;
+    bool devmap_nopartsep = false;
 
     if (setlocale(LC_ALL, "") == NULL ||
         bindtextdomain(PACKAGE, LOCALEDIR) == NULL ||
@@ -80,14 +81,22 @@ int main(int argc, char **argv)
 
     if (argc == 3 && STREQ(argv[2], "-g")) {
         cmd = DISK_GEOMETRY;
+    } else if (argc == 3 && STREQ(argv[2], "-p")) {
+        devmap_nopartsep = true;
     } else if (argc != 2) {
-        fprintf(stderr, _("syntax: %s DEVICE [-g]\n"), argv[0]);
+        fprintf(stderr, _("syntax: %s DEVICE [-g]|[-p]\n"), argv[0]);
         return 1;
     }
 
     path = argv[1];
     if (virIsDevMapperDevice(path)) {
-        partsep = "p";
+        /* The 'devmap_nopartsep' option will not append the partsep of "p"
+         * onto the name unless the 'path' ends in a number
+         */
+        if (c_isdigit(path[strlen(path)-1]) || !devmap_nopartsep)
+            partsep = "p";
+        else
+            partsep = "";
         if (VIR_STRDUP_QUIET(canonical_path, path) < 0)
             return 2;
     } else {

src/storage/storage_backend_disk.c

 /*
  * storage_backend_disk.c: storage backend for disk handling
  *
- * Copyright (C) 2007-2014 Red Hat, Inc.
+ * Copyright (C) 2007-2016 Red Hat, Inc.
  * Copyright (C) 2007-2008 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -325,6 +325,15 @@ virStorageBackendDiskReadPartitions(virStoragePoolObjPtr pool,
                                pool->def->source.devices[0].path,
                                NULL);
 
+    /* Check for the presence of the part_separator='no'. Pass this
+     * along to the libvirt_parthelper as option '-p'. This will cause
+     * libvirt_parthelper to not append the "p" partition separator to
+     * the generated device name, unless the name ends with a number.
+     */
+    if (pool->def->source.devices[0].part_separator ==
+        VIR_TRISTATE_BOOL_NO)
+        virCommandAddArg(cmd, "-p");
+
     /* If a volume is passed, virStorageBackendDiskMakeVol only updates the
      * pool allocation for that single volume.
      */