[libvirt] [PATCH 8/8] storage: Guess the parent if it's not specified for vHBA

[Osier Yang]

This finds the parent for vHBA by iterating over all the HBA
which supports vport_ops capability on the host, and return
the first one which is online, not saturated (vports in use
is less than max_vports).
---
 docs/formatstorage.html.in         |    3 +-
 src/libvirt_private.syms           |    1 +
 src/storage/storage_backend_scsi.c |   10 +++--
 src/util/virutil.c                 |   83 ++++++++++++++++++++++++++++++++++++
 src/util/virutil.h                 |    2 +
 5 files changed, 93 insertions(+), 6 deletions(-)

diff --git a/docs/formatstorage.html.in b/docs/formatstorage.html.in
index af42fed..7315865 100644
--- a/docs/formatstorage.html.in
+++ b/docs/formatstorage.html.in
@@ -99,8 +99,7 @@
         <code>wwpn</code> (<span class="since">1.0.2</span>) indicates
         the (v)HBA. The optional attribute <code>parent</code>
         (<span class="since">1.0.2</span>) specifies the parent device of
-        the (v)HBA. It's optional for HBA, but required for vHBA.
-        <span class="since">Since 0.6.2</span></dd>
+        the (v)HBA. <span class="since">Since 0.6.2</span></dd>
       <dt><code>host</code></dt>
       <dd>Provides the source for pools backed by storage from a
         remote server. Will be used in combination with a <code>directory</code>
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 7334e15..759d630 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1841,6 +1841,7 @@ virFileStripSuffix;
 virFileUnlock;
 virFileWaitForDevices;
 virFileWriteStr;
+virFindFCHostCapableVport;
 virFindFileInPath;
 virFormatIntDecimal;
 virGetDeviceID;
diff --git a/src/storage/storage_backend_scsi.c b/src/storage/storage_backend_scsi.c
index a9b96a3..59abeb0 100644
--- a/src/storage/storage_backend_scsi.c
+++ b/src/storage/storage_backend_scsi.c
@@ -646,10 +646,12 @@ createVport(virStoragePoolSourceAdapter adapter)
                               adapter.data.fchost.wwpn))
         return 0;
 
-    if (!adapter.data.fchost.parent) {
-        virReportError(VIR_ERR_XML_ERROR, "%s",
-                       _("'parent' for vHBA must be specified"));
-        return -1;
+    if (!adapter.data.fchost.parent &&
+        !(adapter.data.fchost.parent = virFindFCHostCapableVport(NULL))) {
+         virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("'parent' for vHBA not specified, and "
+                         "cannot find one on this host"));
+         return -1;
     }
 
     if ((parent_host = getHostNumber(adapter.data.fchost.parent)) < 0)
diff --git a/src/util/virutil.c b/src/util/virutil.c
index 3073337..b9a6166 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -3555,6 +3555,82 @@ cleanup:
     VIR_FREE(wwpn_buf);
     return ret;
 }
+
+# define PORT_STATE_ONLINE "Online"
+
+/* virFindFCHostCapableVport:
+ *
+ * Iterate over the sysfs and find out the first online HBA which
+ * supports vport, and not saturated,.
+ */
+char *
+virFindFCHostCapableVport(const char *sysfs_prefix)
+{
+    const char *prefix = sysfs_prefix ? sysfs_prefix : SYSFS_FC_HOST_PATH;
+    DIR *dir = NULL;
+    struct dirent *entry = NULL;
+    char *max_vports = NULL;
+    char *vports = NULL;
+    char *state = NULL;
+    char *ret = NULL;
+
+    if (!(dir = opendir(prefix))) {
+        virReportSystemError(errno,
+                             _("Failed to opendir path '%s'"),
+                             prefix);
+        return NULL;
+    }
+
+    while ((entry = readdir(dir))) {
+        if (STREQ(entry->d_name, ".") || STREQ(entry->d_name, ".."))
+            continue;
+
+        int host;
+
+        ignore_value(sscanf(entry->d_name, "host%d", &host));
+        if (!virIsCapableVport(NULL, host))
+            continue;
+
+        if (virReadFCHost(NULL, host, "port_state", &state) < 0) {
+             VIR_DEBUG("Failed to read port_state for host%d", host);
+             continue;
+        }
+
+        /* Skip the not online FC host */
+        if (!STREQ(state, PORT_STATE_ONLINE)) {
+            VIR_FREE(state);
+            continue;
+        }
+        VIR_FREE(state);
+
+        if (virReadFCHost(NULL, host, "max_npiv_vports", &max_vports) < 0) {
+             VIR_DEBUG("Failed to read max_npiv_vports for host%d", host);
+             continue;
+        }
+
+        if (virReadFCHost(NULL, host, "npiv_vports_inuse", &vports) < 0) {
+             VIR_DEBUG("Failed to read npiv_vports_inuse for host%d", host);
+             VIR_FREE(max_vports);
+             continue;
+        }
+
+        if ((strlen(max_vports) > strlen(vports)) ||
+            ((strlen(max_vports) == strlen(vports)) &&
+             strcmp(max_vports, vports) > 0)) {
+            ret = strdup(entry->d_name);
+            goto cleanup;
+        }
+
+        VIR_FREE(max_vports);
+        VIR_FREE(vports);
+    }
+
+cleanup:
+    closedir(dir);
+    VIR_FREE(max_vports);
+    VIR_FREE(vports);
+    return ret;
+}
 #else
 int
 virReadFCHost(const char *sysfs_prefix ATTRIBUTE_UNUSED,
@@ -3600,4 +3676,11 @@ virGetFCHostNameByWWN(const char *sysfs_prefix ATTRIBUTE_UNUSED,
     return NULL;
 }
 
+char *
+virFindFCHostCapableVport(const char *sysfs_prefix ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
+    return NULL;
+}
+
 #endif /* __linux__ */
diff --git a/src/util/virutil.h b/src/util/virutil.h
index 78b50a8..3a68134 100644
--- a/src/util/virutil.h
+++ b/src/util/virutil.h
@@ -320,4 +320,6 @@ char * virGetFCHostNameByWWN(const char *sysfs_prefix,
                              const char *wwpn)
     ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 
+char * virFindFCHostCapableVport(const char *sysfs_prefix );
+
 #endif /* __VIR_UTIL_H__ */
-- 
1.7.7.6