ZFS: dedup toggle per pool and dedup option for new datasets

Pool cards show the dedup ratio and can set dedup=on|off on the pool root
dataset (inherited by children); the new-dataset form gets a dedup option.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/web_test.go

@@ -68,12 +68,12 @@ func newTestServer(t *testing.T) (*Server, *sched.Scheduler, *store.Store) {
 		},
 		Pools: []collect.Pool{
 			{Name: "tank", Health: "DEGRADED", Size: 8 << 40, Alloc: 3 << 40, Free: 5 << 40, CapPct: 37, FragPct: 5, Scan: "scrub repaired 0B", LastScrub: &old,
-				Status: "One or more devices could not be opened.", Action: "Attach the missing device", Errors: "No known data errors",
+				Status: "One or more devices could not be opened.", Action: "Attach the missing device", Errors: "No known data errors", DedupRatio: 1.42,
 				Vdevs: []collect.Vdev{{Name: "tank", State: "DEGRADED"}, {Name: "mirror-0", Depth: 1, State: "DEGRADED"}, {Name: "sda", Depth: 2, State: "ONLINE", Cksum: 2}, {Name: "123", Depth: 2, State: "UNAVAIL", Note: "was /dev/sdb1"}}},
 			{Name: "tmp_pool", Health: "ONLINE", Size: 1 << 40, Alloc: 900 << 30, Free: 124 << 30, CapPct: 88, Scrubbing: true, Scan: "scrub in progress"},
 		},
 		Datasets: []collect.Dataset{
-			{Name: "tank", Used: 3 << 40, Avail: 5 << 40, Refer: 1 << 20, Mountpoint: "/tank"},
+			{Name: "tank", Used: 3 << 40, Avail: 5 << 40, Refer: 1 << 20, Mountpoint: "/tank", Dedup: "on"},
 			{Name: "tank/empty", Used: 96 << 10, Avail: 5 << 40, Refer: 96 << 10, Mountpoint: "/tank/empty"},
 			{Name: "tank/data", Used: 3 << 40, Avail: 5 << 40, Refer: 3 << 40, Mountpoint: "/tank/data"},
 			{Name: "tank/parent", Used: 96 << 10, Avail: 5 << 40, Refer: 96 << 10, Mountpoint: "/tank/parent"},
@@ -245,7 +245,7 @@ func TestZfsPageControls(t *testing.T) {
 	rec := httptest.NewRecorder()
 	srv.ServeHTTP(rec, httptest.NewRequest("GET", "/zfs?msg=hello", nil))
 	body := rec.Body.String()
-	for _, want := range []string{"New dataset in tank", "New dataset in tmp_pool", "hello", `value="1000:1000"`, "type tank/empty to confirm"} {
+	for _, want := range []string{"New dataset in tank", "New dataset in tmp_pool", "hello", `value="1000:1000"`, "type tank/empty to confirm", `action="/zfs/dedup"`, "Dedup for tmp_pool", "ratio 1.42x"} {
 		if !strings.Contains(body, want) {
 			t.Errorf("zfs page missing %q", want)
 		}
@@ -274,6 +274,7 @@ func TestZfsCreate(t *testing.T) {
 		{"pool": {"tank"}, "name": {"x"}, "quota": {"lots"}},    // bad quota
 		{"pool": {"tank"}, "name": {"x"}, "owner": {"ansible"}}, // bad owner
 		{"pool": {"tank"}, "name": {"x"}, "compression": {"gzip"}},
+		{"pool": {"tank"}, "name": {"x"}, "dedup": {"verify"}},
 	}
 	for _, form := range bad {
 		f.calls = nil
@@ -289,11 +290,11 @@ func TestZfsCreate(t *testing.T) {
 		}
 	}
 
-	rec := postForm(srv, "/zfs/create", url.Values{"pool": {"tank"}, "name": {"/media/video/"}, "owner": {"1000:1000"}, "compression": {"lz4"}, "quota": {"100g"}})
+	rec := postForm(srv, "/zfs/create", url.Values{"pool": {"tank"}, "name": {"/media/video/"}, "owner": {"1000:1000"}, "compression": {"lz4"}, "dedup": {"on"}, "quota": {"100g"}})
 	if rec.Code != http.StatusSeeOther || !strings.Contains(rec.Header().Get("Location"), "created") {
 		t.Fatalf("status %d location %q body %s", rec.Code, rec.Header().Get("Location"), rec.Body.String())
 	}
-	want := "zfs create -p -o compression=lz4 -o quota=100G tank/media/video"
+	want := "zfs create -p -o compression=lz4 -o dedup=on -o quota=100G tank/media/video"
 	if len(f.calls) != 3 || f.calls[0] != want || f.calls[2] != "chown 1000:1000 /tank/media/video" {
 		t.Errorf("calls = %v", f.calls)
 	}
@@ -307,6 +308,44 @@ func TestZfsCreate(t *testing.T) {
 	}
 }
 
+func TestZfsDedup(t *testing.T) {
+	srv, _, _ := newTestServer(t)
+	f := &fakeRunner{}
+	srv.admin = zfsadm.New(f.run)
+
+	bad := []url.Values{
+		{"pool": {"nope"}, "dedup": {"on"}},      // unknown pool
+		{"pool": {"tank/data"}, "dedup": {"on"}}, // not a pool
+		{"pool": {"tank"}, "dedup": {"verify"}},  // unsupported value
+		{"pool": {"tank"}},                       // missing value
+	}
+	for _, form := range bad {
+		f.calls = nil
+		rec := postForm(srv, "/zfs/dedup", form)
+		if rec.Code != 200 || !strings.Contains(rec.Body.String(), "Dedup not changed") {
+			t.Errorf("%v: status %d, no error shown", form, rec.Code)
+		}
+		if len(f.calls) != 0 {
+			t.Errorf("%v: commands ran: %v", form, f.calls)
+		}
+	}
+
+	rec := postForm(srv, "/zfs/dedup", url.Values{"pool": {"tmp_pool"}, "dedup": {"on"}})
+	if rec.Code != http.StatusSeeOther || !strings.Contains(rec.Header().Get("Location"), "#tmp_pool") {
+		t.Fatalf("status %d location %q", rec.Code, rec.Header().Get("Location"))
+	}
+	if len(f.calls) != 1 || f.calls[0] != "zfs set dedup=on tmp_pool" {
+		t.Errorf("calls = %v", f.calls)
+	}
+
+	f = &fakeRunner{fail: "zfs set"}
+	srv.admin = zfsadm.New(f.run)
+	rec = postForm(srv, "/zfs/dedup", url.Values{"pool": {"tank"}, "dedup": {"off"}})
+	if rec.Code != 200 || !strings.Contains(rec.Body.String(), "cannot do that") {
+		t.Errorf("failure not reported: %d", rec.Code)
+	}
+}
+
 func TestZfsDestroy(t *testing.T) {
 	srv, _, _ := newTestServer(t)
 	f := &fakeRunner{}