From 2ccbfd8f528f6fff2ad95f2581812cbcd04ad493 Mon Sep 17 00:00:00 2001
From: Jean-Marc Saffroy <jean.marc.saffroy@scality.com>
Date: Tue, 15 Jan 2013 00:27:42 +0100
Subject: Add a volume driver in Nova for Scality SOFS

Scality SOFS is a network filesystem mounted with FUSE, with most
options given in a configuration file. Given a mount point and a SOFS
configuration file as driver options, the Scality volume driver mounts
SOFS, and then creates, accesses and deletes volumes as regular
(sparse) files on SOFS.

Change-Id: I84bf268e5a2c5c33b8706830e8067914fae44aed
Implements: blueprint scality-volume-driver
---
 nova/virt/libvirt/driver.py |  4 ++-
 nova/virt/libvirt/volume.py | 79 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)

(limited to 'nova/virt')

diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 6f1cfef6f..57e364115 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -166,7 +166,9 @@ libvirt_opts = [
                   'glusterfs='
                       'nova.virt.libvirt.volume.LibvirtGlusterfsVolumeDriver',
                   'fibre_channel=nova.virt.libvirt.volume.'
-                      'LibvirtFibreChannelVolumeDriver'
+                      'LibvirtFibreChannelVolumeDriver',
+                  'scality='
+                      'nova.virt.libvirt.volume.LibvirtScalityVolumeDriver',
                   ],
                 help='Libvirt handlers for remote volumes.'),
     cfg.StrOpt('libvirt_disk_prefix',
diff --git a/nova/virt/libvirt/volume.py b/nova/virt/libvirt/volume.py
index a5bd2dd43..577cfee2c 100644
--- a/nova/virt/libvirt/volume.py
+++ b/nova/virt/libvirt/volume.py
@@ -21,6 +21,8 @@
 import hashlib
 import os
 import time
+import urllib2
+import urlparse
 
 from oslo.config import cfg
 
@@ -63,6 +65,12 @@ volume_opts = [
     cfg.BoolOpt('libvirt_iscsi_use_multipath',
                 default=False,
                 help='use multipath connection of the iSCSI volume'),
+    cfg.StrOpt('scality_sofs_config',
+               default=None,
+               help='Path or URL to Scality SOFS configuration file'),
+    cfg.StrOpt('scality_sofs_mount_point',
+               default='$state_path/scality',
+               help='Base dir where Scality SOFS shall be mounted'),
     ]
 
 CONF = cfg.CONF
@@ -749,3 +757,74 @@ class LibvirtFibreChannelVolumeDriver(LibvirtBaseVolumeDriver):
         # all of them
         for device in devices:
             linuxscsi.remove_device(device)
+
+
+class LibvirtScalityVolumeDriver(LibvirtBaseVolumeDriver):
+    """Scality SOFS Nova driver. Provide hypervisors with access
+    to sparse files on SOFS. """
+
+    def __init__(self, connection):
+        """Create back-end to SOFS and check connection."""
+        super(LibvirtScalityVolumeDriver,
+              self).__init__(connection, is_block_dev=False)
+
+    def connect_volume(self, connection_info, disk_info):
+        """Connect the volume. Returns xml for libvirt."""
+        self._check_prerequisites()
+        self._mount_sofs()
+        conf = super(LibvirtScalityVolumeDriver,
+                     self).connect_volume(connection_info, disk_info)
+        path = os.path.join(CONF.scality_sofs_mount_point,
+                            connection_info['data']['sofs_path'])
+        conf.source_type = 'file'
+        conf.source_path = path
+
+        # The default driver cache policy is 'none', and this causes
+        # qemu/kvm to open the volume file with O_DIRECT, which is
+        # rejected by FUSE (on kernels older than 3.3). Scality SOFS
+        # is FUSE based, so we must provide a more sensible default.
+        conf.driver_cache = 'writethrough'
+
+        return conf
+
+    def _check_prerequisites(self):
+        """Sanity checks before attempting to mount SOFS."""
+
+        # config is mandatory
+        config = CONF.scality_sofs_config
+        if not config:
+            msg = _("Value required for 'scality_sofs_config'")
+            LOG.warn(msg)
+            raise exception.NovaException(msg)
+
+        # config can be a file path or a URL, check it
+        if urlparse.urlparse(config).scheme == '':
+            # turn local path into URL
+            config = 'file://%s' % config
+        try:
+            urllib2.urlopen(config, timeout=5).close()
+        except urllib2.URLError as e:
+            msg = _("Cannot access 'scality_sofs_config': %s") % e
+            LOG.warn(msg)
+            raise exception.NovaException(msg)
+
+        # mount.sofs must be installed
+        if not os.access('/sbin/mount.sofs', os.X_OK):
+            msg = _("Cannot execute /sbin/mount.sofs")
+            LOG.warn(msg)
+            raise exception.NovaException(msg)
+
+    def _mount_sofs(self):
+        config = CONF.scality_sofs_config
+        mount_path = CONF.scality_sofs_mount_point
+        sysdir = os.path.join(mount_path, 'sys')
+
+        if not os.path.isdir(mount_path):
+            utils.execute('mkdir', '-p', mount_path)
+        if not os.path.isdir(sysdir):
+            utils.execute('mount', '-t', 'sofs', config, mount_path,
+                          run_as_root=True)
+        if not os.path.isdir(sysdir):
+            msg = _("Cannot mount Scality SOFS, check syslog for errors")
+            LOG.warn(msg)
+            raise exception.NovaException(msg)
-- 
cgit