storage: Tell people that big mdraids really should have a bitmap

pkg/storaged/mdraid-details.jsx

@@ -27,7 +27,7 @@ import * as utils from "./utils.js";
 import { StdDetailsLayout } from "./details.jsx";
 import { SidePanel } from "./side-panel.jsx";
 import { Block } from "./content-views.jsx";
-import { StorageButton, StorageOnOff } from "./storage-controls.jsx";
+import { StorageButton } from "./storage-controls.jsx";
 import {
     dialog_open, SelectSpaces, BlockingMessage, TeardownMessage,
     init_active_usage_processes
@@ -180,23 +180,6 @@ export class MDRaidDetails extends React.Component {
         if (mdraid.ChunkSize > 0)
             level += ", " + cockpit.format(_("$0 chunk size"), utils.fmt_size(mdraid.ChunkSize));
 
-        function toggle_bitmap(val) {
-            return mdraid.SetBitmapLocation(utils.encode_filename(val ? 'internal' : 'none'), {});
-        }
-
-        let bitmap = null;
-        if (mdraid.BitmapLocation) {
-            const value = utils.decode_filename(mdraid.BitmapLocation) != "none";
-            bitmap = (
-                <DescriptionListGroup>
-                    <DescriptionListTerm>{_("storage", "Bitmap")}</DescriptionListTerm>
-                    <DescriptionListDescription>
-                        <StorageOnOff state={value} aria-label={_("Toggle bitmap")} onChange={toggle_bitmap} />
-                    </DescriptionListDescription>
-                </DescriptionListGroup>
-            );
-        }
-
         let degraded_message = null;
         if (mdraid.Degraded > 0) {
             const text = cockpit.format(
@@ -208,6 +191,24 @@ export class MDRaidDetails extends React.Component {
             );
         }
 
+        function fix_bitmap() {
+            return mdraid.SetBitmapLocation(utils.encode_filename("internal"), { });
+        }
+
+        let bitmap_message = null;
+        if (mdraid.Level != "raid0" &&
+            client.mdraids_members[mdraid.path].some(m => m.Size > 100 * 1024 * 1024 * 1024) &&
+            mdraid.BitmapLocation && utils.decode_filename(mdraid.BitmapLocation) == "none") {
+            bitmap_message = (
+                <Alert isInline variant="warning"
+                       title={_("This RAID array has no write-intent bitmap. Such a bitmap can reduce sychronization times significantly.")}>
+                    <div className="storage_alert_action_buttons">
+                        <StorageButton onClick={fix_bitmap}>{_("Add a bitmap")}</StorageButton>
+                    </div>
+                </Alert>
+            );
+        }
+
         /* Older versions of Udisks/storaged don't have a Running property */
         let running = mdraid.Running;
         if (running === undefined)
@@ -338,9 +339,6 @@ export class MDRaidDetails extends React.Component {
                             <DescriptionListTerm>{_("storage", "RAID level")}</DescriptionListTerm>
                             <DescriptionListDescription>{ level }</DescriptionListDescription>
                         </DescriptionListGroup>
-
-                        { bitmap }
-
                         <DescriptionListGroup>
                             <DescriptionListTerm>{_("storage", "State")}</DescriptionListTerm>
                             <DescriptionListDescription>{ running ? _("Running") : _("Not running") }</DescriptionListDescription>
@@ -355,7 +353,7 @@ export class MDRaidDetails extends React.Component {
         const content = <Block client={this.props.client} block={block} />;
 
         return <StdDetailsLayout client={this.props.client}
-                                 alerts={[degraded_message]}
+                                 alerts={[degraded_message, bitmap_message]}
                                  header={ header }
                                  sidebar={ sidebar }
                                  content={ content }

test/common/storagelib.py

@@ -66,17 +66,22 @@ def add_loopback_disk(self, size=50, name=None):
 
         The disk gets removed automatically when the test ends. This is safe for @nondestructive tests.
 
-        Unlike add_ram_disk(), this can be called multiple times, and is less size constrained.
-        However, loopback devices look quite special to the OS, so they are not a very good
-        simulation of a "real" disk.
+        Unlike add_ram_disk(), this can be called multiple times, and
+        is less size constrained.  The backing file starts out sparse,
+        so this can be used to create massive block devices, as long
+        as you are careful to not actually use much of it.
+
+        However, loopback devices look quite special to the OS, so
+        they are not a very good simulation of a "real" disk.
 
         Return the device name.
+
         """
         # HACK: https://bugzilla.redhat.com/show_bug.cgi?id=1969408
         # It would be nicer to remove $F immediately after the call to
         # losetup, but that will break some versions of lvm2.
         dev = self.machine.execute("F=$(mktemp /var/tmp/loop.XXXX); "
-                                   "dd if=/dev/zero of=$F bs=1000000 count=%s; "
+                                   "truncate --size=%sMB $F; "
                                    "losetup --show %s $F" % (size, name if name else "--find")).strip()
         # If this device had partions in its last incarnation on this
         # machine, they might come back for unknown reasons, in a

test/verify/check-storage-mdraid

@@ -343,6 +343,44 @@ class TestStorageMdRaid(storagelib.StorageCase):
         # The last disk can not be removed
         b.wait_visible('#detail-sidebar .sidepanel-row:contains(DISK2) button:disabled')
 
+    def testBitmap(self):
+        m = self.machine
+        b = self.browser
+
+        self.login_and_go("/storage")
+
+        # Make two huge block devices, so that we can make a array
+        # that is beyond the threshold where Cockpit and mdadm start
+        # to worry about bitmaps.  The backing files are sparse, so
+        # this is okay as long nobody actually writes a lot to these
+        # devices.
+
+        dev1 = self.add_loopback_disk(110000)
+        dev2 = self.add_loopback_disk(110000)
+
+        # We need to use "--assume-clean" so that mdraid doesn't try
+        # to write 110GB to one of the devices during synchronization.
+
+        m.execute(f"mdadm --create md0 --level=1 --assume-clean --run --raid-devices=2 {dev1} {dev2}")
+        m.execute("udevadm trigger")
+
+        b.wait_in_text("#devices", "md0")
+        b.click('#devices .sidepanel-row:contains("md")')
+        b.wait_visible('#storage-detail')
+
+        self.wait_states({dev1: "In sync",
+                          dev2: "In sync"})
+
+        b.wait_not_present('.pf-v5-c-alert:contains("This RAID array has no write-intent bitmap")')
+
+        # Remove the bitmap, Cockpit should complain and let us put it back.
+
+        m.execute("mdadm --grow --bitmap=none /dev/md/md0; udevadm trigger /dev/md/md0")
+
+        b.wait_visible('.pf-v5-c-alert:contains("This RAID array has no write-intent bitmap")')
+        b.click('button:contains("Add a bitmap")')
+        b.wait_not_present('.pf-v5-c-alert:contains("This RAID array has no write-intent bitmap")')
+
 
 if __name__ == '__main__':
     testlib.test_main()