util: Add helper to get the scsi host name by iterating over sysfs

The helper iterates over sysfs, to find out the matched scsi host
name by comparing the wwnn,wwpn pair. It will be used by checkPool
and refreshPool of storage scsi backend. New helper getAdapterName
is introduced in storage_backend_scsi.c, which uses the new util
helper virGetFCHostNameByWWN to get the fc_host adapter name.

src/libvirt_private.syms

@@ -1856,6 +1856,7 @@ virFindFileInPath;
 virFormatIntDecimal;
 virGetDeviceID;
 virGetDeviceUnprivSGIO;
+virGetFCHostNameByWWN;
 virGetGroupID;
 virGetGroupName;
 virGetHostname;

src/storage/storage_backend_scsi.c

@@ -603,6 +603,8 @@ getHostNumber(const char *adapter_name,
      */
     if (STRPREFIX(host, "scsi_host")) {
         host += strlen("scsi_host");
+    } else if (STRPREFIX(host, "fc_host")) {
+        host += strlen("fc_host");
     } else if (STRPREFIX(host, "host")) {
         host += strlen("host");
     } else {
@@ -622,42 +624,73 @@ getHostNumber(const char *adapter_name,
     return 0;
 }
 
+static char *
+getAdapterName(virStoragePoolSourceAdapter adapter)
+{
+    char *name = NULL;
+
+    if (adapter.type != VIR_STORAGE_POOL_SOURCE_ADAPTER_TYPE_FC_HOST)
+        return strdup(adapter.data.name);
+
+    if (!(name = virGetFCHostNameByWWN(NULL,
+                                       adapter.data.fchost.wwnn,
+                                       adapter.data.fchost.wwpn))) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("Failed to find SCSI host with wwnn='%s', "
+                         "wwpn='%s'"), adapter.data.fchost.wwnn,
+                       adapter.data.fchost.wwpn);
+    }
+
+    return name;
+}
+
 static int
 virStorageBackendSCSICheckPool(virConnectPtr conn ATTRIBUTE_UNUSED,
                                virStoragePoolObjPtr pool,
                                bool *isActive)
 {
-    char *path;
+    char *path = NULL;
+    char *name = NULL;
     unsigned int host;
+    int ret = -1;
 
     *isActive = false;
 
-    if (getHostNumber(pool->def->source.adapter.data.name, &host) < 0)
+    if (!(name = getAdapterName(pool->def->source.adapter)))
         return -1;
 
+    if (getHostNumber(name, &host) < 0)
+        goto cleanup;
+
     if (virAsprintf(&path, "/sys/class/scsi_host/host%d", host) < 0) {
         virReportOOMError();
-        return -1;
+        goto cleanup;
     }
 
     if (access(path, F_OK) == 0)
         *isActive = true;
 
+    ret = 0;
+cleanup:
     VIR_FREE(path);
-
-    return 0;
+    VIR_FREE(name);
+    return ret;
 }
 
 static int
 virStorageBackendSCSIRefreshPool(virConnectPtr conn ATTRIBUTE_UNUSED,
                                  virStoragePoolObjPtr pool)
 {
-    int ret = -1;
+    char *name = NULL;
     unsigned int host;
+    int ret = -1;
 
     pool->def->allocation = pool->def->capacity = pool->def->available = 0;
 
-    if (getHostNumber(pool->def->source.adapter.data.name, &host) < 0)
+    if (!(name = getAdapterName(pool->def->source.adapter)))
+        return -1;
+
+    if (getHostNumber(name, &host) < 0)
         goto out;
 
     VIR_DEBUG("Scanning host%u", host);
@@ -669,6 +702,7 @@ virStorageBackendSCSIRefreshPool(virConnectPtr conn ATTRIBUTE_UNUSED,
 
     ret = 0;
 out:
+    VIR_FREE(name);
     return ret;
 }
 

src/util/virutil.c

@@ -26,6 +26,7 @@
 
 #include <config.h>
 
+#include <dirent.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdlib.h>
@@ -3570,6 +3571,105 @@ cleanup:
     VIR_FREE(operation_path);
     return ret;
 }
+
+/* virGetHostNameByWWN:
+ *
+ * Iterate over the sysfs tree to get SCSI host name (e.g. scsi_host5)
+ * by wwnn,wwpn pair.
+ */
+char *
+virGetFCHostNameByWWN(const char *sysfs_prefix,
+                      const char *wwnn,
+                      const char *wwpn)
+{
+    const char *prefix = sysfs_prefix ? sysfs_prefix : SYSFS_FC_HOST_PATH;
+    struct dirent *entry = NULL;
+    DIR *dir = NULL;
+    char *wwnn_path = NULL;
+    char *wwpn_path = NULL;
+    char *wwnn_buf = NULL;
+    char *wwpn_buf = NULL;
+    char *p;
+    char *ret = NULL;
+
+    if (!(dir = opendir(prefix))) {
+        virReportSystemError(errno,
+                             _("Failed to opendir path '%s'"),
+                             prefix);
+        return NULL;
+    }
+
+# define READ_WWN(wwn_path, buf)                      \
+    do {                                              \
+        if (virFileReadAll(wwn_path, 1024, &buf) < 0) \
+            goto cleanup;                             \
+        if ((p = strchr(buf, '\n')))                  \
+            *p = '\0';                                \
+        if (STRPREFIX(buf, "0x"))                     \
+            p = buf + strlen("0x");                   \
+        else                                          \
+            p = buf;                                  \
+    } while (0)
+
+    while ((entry = readdir(dir))) {
+        if (entry->d_name[0] == '.')
+            continue;
+
+        if (virAsprintf(&wwnn_path, "%s%s/node_name", prefix,
+                        entry->d_name) < 0) {
+            virReportOOMError();
+            goto cleanup;
+        }
+
+        if (!virFileExists(wwnn_path)) {
+            VIR_FREE(wwnn_path);
+            continue;
+        }
+
+        READ_WWN(wwnn_path, wwnn_buf);
+
+        if (STRNEQ(wwnn, p)) {
+            VIR_FREE(wwnn_buf);
+            VIR_FREE(wwnn_path);
+            continue;
+        }
+
+        if (virAsprintf(&wwpn_path, "%s%s/port_name", prefix,
+                        entry->d_name) < 0) {
+            virReportOOMError();
+            goto cleanup;
+        }
+
+        if (!virFileExists(wwpn_path)) {
+            VIR_FREE(wwnn_buf);
+            VIR_FREE(wwnn_path);
+            VIR_FREE(wwpn_path);
+            continue;
+        }
+
+        READ_WWN(wwpn_path, wwpn_buf);
+
+        if (STRNEQ(wwpn, p)) {
+            VIR_FREE(wwnn_path);
+            VIR_FREE(wwpn_path);
+            VIR_FREE(wwnn_buf);
+            VIR_FREE(wwpn_buf);
+            continue;
+        }
+
+        ret = strdup(entry->d_name);
+        break;
+    }
+
+cleanup:
+# undef READ_WWN
+    closedir(dir);
+    VIR_FREE(wwnn_path);
+    VIR_FREE(wwpn_path);
+    VIR_FREE(wwnn_buf);
+    VIR_FREE(wwpn_buf);
+    return ret;
+}
 #else
 int
 virReadFCHost(const char *sysfs_prefix ATTRIBUTE_UNUSED,
@@ -3607,4 +3707,13 @@ virManageVport(const int parent_host ATTRIBUTE_UNUSED,
     return -1;
 }
 
+char *
+virGetFCHostNameByWWN(const char *sysfs_prefix ATTRIBUTE_UNUSED,
+                      const char *wwnn ATTRIBUTE_UNUSED,
+                      const char *wwpn ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
+    return NULL;
+}
+
 #endif /* __linux__ */

src/util/virutil.h

@@ -295,7 +295,7 @@ int virSetDeviceUnprivSGIO(const char *path,
 int virGetDeviceUnprivSGIO(const char *path,
                            const char *sysfs_dir,
                            int *unpriv_sgio);
-char * virGetUnprivSGIOSysfsPath(const char *path,
+char *virGetUnprivSGIOSysfsPath(const char *path,
                                 const char *sysfs_dir);
 int virReadFCHost(const char *sysfs_prefix,
                   int host,
@@ -317,4 +317,9 @@ int virManageVport(const int parent_host,
                    int operation)
     ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 
+char *virGetFCHostNameByWWN(const char *sysfs_prefix,
+                            const char *wwnn,
+                            const char *wwpn)
+    ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
+
 #endif /* __VIR_UTIL_H__ */