[PATCH v3] libxl: add discard support to libxl_device_disk

[Olaf Hering <olaf@xxxxxxxxx>]

Translate libvirt discard settings into libxl-4.5 discard settings.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
---
v3:
 passing discard= with old libxl is now a fatal error
v2:
 add cast to switch variable to let compiler check if the code handles
 all enum values

 src/libxl/libxl_conf.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 8eeaf82..538cfa4 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -715,6 +715,35 @@ libxlMakeDomBuildInfo(virDomainDefPtr def,
     return -1;
 }
 
+static int
+libxlDiskSetDiscard(libxl_device_disk *x_disk, int discard)
+{
+    if (!x_disk->readwrite)
+        return 0;
+#if defined(LIBXL_HAVE_LIBXL_DEVICE_DISK_DISCARD_ENABLE)
+    switch ((enum virDomainDiskDiscard)discard) {
+    case VIR_DOMAIN_DISK_DISCARD_DEFAULT:
+    case VIR_DOMAIN_DISK_DISCARD_LAST:
+        break;
+    case VIR_DOMAIN_DISK_DISCARD_UNMAP:
+        libxl_defbool_set(&x_disk->discard_enable, true);
+        break;
+    case VIR_DOMAIN_DISK_DISCARD_IGNORE:
+        libxl_defbool_set(&x_disk->discard_enable, false);
+        break;
+    }
+    return 0;
+#else
+    if (discard == VIR_DOMAIN_DISK_DISCARD_DEFAULT)
+        return 0;
+    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                   _("This version of libxenlight does not support "
+                     "disk 'discard' option passing"));
+    return -1;
+#endif
+}
+
+
 int
 libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
 {
@@ -829,6 +858,8 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
     x_disk->removable = 1;
     x_disk->readwrite = !l_disk->readonly;
     x_disk->is_cdrom = l_disk->device == VIR_DOMAIN_DISK_DEVICE_CDROM ? 1 : 0;
+    if (libxlDiskSetDiscard(x_disk, l_disk->discard) < 0)
+        return -1;
     /* An empty CDROM must have the empty format, otherwise libxl fails. */
     if (x_disk->is_cdrom && !x_disk->pdev_path)
         x_disk->format = LIBXL_DISK_FORMAT_EMPTY;

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