Subject: addstorage: Return to using qcow2 sparse by default
From: Cole Robinson crobinso@redhat.com Sat Sep 19 18:06:45 2020 -0400
Date: Sun Sep 20 10:11:36 2020 -0400:
Git: ba08f84b3408744e9aa9763d100e8aa217c1f5ff

https://bugzilla.redhat.com/show_bug.cgi?id=1759454

See 15a6a7e2105440df528f75c4df4d2471df28bd1e

The idea behind virt-manager's sparse vs nonsparse default, is that if
the user selected 'raw' for as the default image format, assume they
want to maximize performance, so fully allocate the disk.

qcow2 didn't support anything except sparse, so the sparse=True vs
sparse=False made no difference. So we always set sparse=False

Then qcow2 grows non-sparse support, and virt-manager is suddenly
defaulting to it, which is not the intention.

Default to sparse when requested format isn't raw

Signed-off-by: Cole Robinson <crobinso@redhat.com>

Index: virt-manager-3.0.0/tests/uitests/test_addhardware.py
===================================================================
--- virt-manager-3.0.0.orig/tests/uitests/test_addhardware.py
+++ virt-manager-3.0.0/tests/uitests/test_addhardware.py
@@ -152,11 +152,8 @@ class AddHardware(lib.testcase.UITestCas
         tab.combo_select("Cache mode:", "none")
         tab.combo_select("Discard mode:", "ignore")
         tab.combo_select("Detect zeroes:", "unmap")
-        # Size too big
-        tab.find("GiB", "spin button").set_text("2000")
-        self._finish(addhw, check=None)
-        self.app.click_alert_button("not enough free space", "Close")
-        tab.find("GiB", "spin button").set_text("1.5")
+        # High number but we are non-sparse by default so it won't complain
+        tab.find("GiB", "spin button").set_text("200000")
         self._finish(addhw, check=details)
 
         # USB disk with removable setting
Index: virt-manager-3.0.0/tests/uitests/test_createvm.py
===================================================================
--- virt-manager-3.0.0.orig/tests/uitests/test_createvm.py
+++ virt-manager-3.0.0/tests/uitests/test_createvm.py
@@ -201,12 +201,11 @@ class NewVM(lib.testcase.UITestCase):
         self.forward(newvm)
         self.forward(newvm)
 
-        # Trigger size validation failure
+        # qcow2 default shouldn't trigger size error
         sizetext = newvm.find(None, "spin button", "GiB")
         sizetext.set_text("10000000")
-        self.forward(newvm, check=False)
-        self.app.click_alert_button("Storage parameter error", "OK")
-        sizetext.set_text("1")
+        _forward(newvm)
+        _back(newvm)
 
         # Use the storage browser to select a local file
         storagetext = newvm.find("storage-entry")
Index: virt-manager-3.0.0/virtManager/device/addstorage.py
===================================================================
--- virt-manager-3.0.0.orig/virtManager/device/addstorage.py
+++ virt-manager-3.0.0/virtManager/device/addstorage.py
@@ -251,14 +251,18 @@ class vmmAddStorage(vmmGObjectUI):
         if disk.wants_storage_creation():
             pool = disk.get_parent_pool()
             size = uiutil.spin_get_helper(self.widget("storage-size"))
-            sparse = False
+            fmt = self.conn.get_default_storage_format()
+
+            # If the user changed the default disk format to raw, assume
+            # they want to maximize performance, so fully allocate the
+            # disk image. Otherwise use sparse
+            sparse = fmt != 'raw'
 
             vol_install = virtinst.DeviceDisk.build_vol_install(
                 disk.conn, os.path.basename(disk.path), pool,
                 size, sparse)
             disk.set_vol_install(vol_install)
 
-            fmt = self.conn.get_default_storage_format()
             if disk.get_vol_install().supports_format():
                 log.debug("Using default prefs format=%s for path=%s",
                     fmt, disk.path)