virt-install --disk discard= support

(crobinso: Remove default overriding, add test cases)

man/virt-install.pod

@@ -573,6 +573,13 @@ The cache value can be 'none', 'writethrough', or 'writeback'.
 'writethrough' provides read caching. 'writeback' provides
 read and write caching.
 
+=item B<discard>
+
+Whether discard (also known as "trim" or "unmap") requests are ignored
+or passed to the filesystem. The value can be either "unmap" (allow
+the discard request to be passed) or "ignore" (ignore the discard
+request). Since 1.0.6 (QEMU and KVM only)
+
 =item B<format>
 
 Disk image format. For file volumes, this can be 'raw', 'qcow2', 'vmdk', etc. See format types in L<http://libvirt.org/storage.html> for possible values. This is often mapped to the B<driver_type> value as well.

tests/cli-test-xml/compare/virt-install-many-devices.xml

@@ -52,7 +52,7 @@
       <boot order="2"/>
     </disk>
     <disk type="file" device="disk">
-      <driver error_policy="enospace"/>
+      <driver discard="unmap" error_policy="enospace"/>
       <source file="/dev/default-pool/new1.img"/>
       <target dev="hdb" bus="ide"/>
       <readonly/>
@@ -196,7 +196,7 @@
       <boot order="2"/>
     </disk>
     <disk type="file" device="disk">
-      <driver error_policy="enospace"/>
+      <driver discard="unmap" error_policy="enospace"/>
       <source file="/dev/default-pool/new1.img"/>
       <target dev="hdb" bus="ide"/>
       <readonly/>

tests/cli-test-xml/compare/virt-xml-edit-clear-disk.xml

@@ -4,10 +4,10 @@
 -    <disk type="block" device="floppy">
 -      <source dev="/dev/null"/>
 +    <disk device="floppy">
-+      <source file="/foo/bar"/>
        <target dev="fda" bus="fdc"/>
 -      <boot order="5"/>
 -      <address type="drive" controller="0" bus="0" target="0" unit="0"/>
++      <source file="/foo/bar"/>
      </disk>
      <disk type="dir" device="floppy">
        <source dir="/tmp"/>

tests/clitest.py

@@ -554,7 +554,7 @@ c.add_compare("""--hvm --pxe \
 --controller usb,model=ich9-uhci2,address=0:0:4.1,index=0,master=2 \
 --controller usb,model=ich9-uhci3,address=0:0:4.2,index=0,master=4 \
 --disk %(EXISTUPPER)s,cache=writeback,io=threads,perms=sh,serial=WD-WMAP9A966149,boot_order=2 \
---disk %(NEWIMG1)s,sparse=false,size=.001,perms=ro,error_policy=enospace \
+--disk %(NEWIMG1)s,sparse=false,size=.001,perms=ro,error_policy=enospace,discard=unmap \
 --disk device=cdrom,bus=sata,read_bytes_sec=1,read_iops_sec=2,total_bytes_sec=10,total_iops_sec=20,write_bytes_sec=5,write_iops_sec=6 \
 --disk size=1 \
 --serial tcp,host=:2222,mode=bind,protocol=telnet \

tests/xmlparse-xml/change-disk-out.xml

@@ -50,7 +50,7 @@
         <total_iops_sec>5</total_iops_sec>
         <total_bytes_sec>6</total_bytes_sec>
       </iotune>
-      <driver cache="writeback" io="native"/>
+      <driver cache="writeback" discard="unmap" io="native"/>
       <source file="/dev/default-pool/default-vol" startupPolicy="optional"/>
       <shareable/>
     </disk>

tests/xmlparse.py

@@ -331,6 +331,7 @@ class XMLParseTest(unittest.TestCase):
         check("driver_cache", None, "writeback")
         check("driver_io", None, "threads")
         check("driver_io", "threads", "native")
+        check("driver_discard", None, "unmap")
         check("iotune_ris", 1, 0)
         check("iotune_rbs", 2, 0)
         check("iotune_wis", 3, 0)

virtinst/cli.py

@@ -1638,6 +1638,7 @@ class ParserDisk(VirtCLIParser):
         self.set_param("bus", "bus")
         self.set_param("removable", "removable", is_onoff=True)
         self.set_param("driver_cache", "cache")
+        self.set_param("driver_discard", "discard")
         self.set_param("driver_name", "driver_name")
         self.set_param("driver_type", "driver_type")
         self.set_param("driver_io", "io")

virtinst/devicedisk.py

@@ -169,6 +169,10 @@ class VirtualDisk(VirtualDevice):
     cache_types = [CACHE_MODE_NONE, CACHE_MODE_WRITETHROUGH,
         CACHE_MODE_WRITEBACK, CACHE_MODE_DIRECTSYNC, CACHE_MODE_UNSAFE]
 
+    DISCARD_MODE_IGNORE = "ignore"
+    DISCARD_MODE_UNMAP = "unmap"
+    discard_types = [DISCARD_MODE_IGNORE, DISCARD_MODE_UNMAP]
+
     DEVICE_DISK = "disk"
     DEVICE_LUN = "lun"
     DEVICE_CDROM = "cdrom"
@@ -494,7 +498,7 @@ class VirtualDisk(VirtualDevice):
     _XML_PROP_ORDER = [
         "type", "device",
         "driver_name", "driver_type",
-        "driver_cache", "driver_io", "error_policy",
+        "driver_cache", "driver_discard", "driver_io", "error_policy",
         "_xmlpath", "target", "bus",
     ]
 
@@ -607,6 +611,7 @@ class VirtualDisk(VirtualDevice):
     read_only = XMLProperty("./readonly", is_bool=True)
     shareable = XMLProperty("./shareable", is_bool=True)
     driver_cache = XMLProperty("./driver/@cache")
+    driver_discard = XMLProperty("./driver/@discard")
     driver_io = XMLProperty("./driver/@io")
 
     error_policy = XMLProperty("./driver/@error_policy")