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/handlers.go

@@ -124,7 +124,9 @@ type zfsVM struct {
 	S        sched.Status
 	Th       config.Thresholds
 	Datasets []datasetRow
-	Form     createForm // last submitted values (re-rendered after an error)
+	// PoolDedup maps a pool to the dedup property of its root dataset.
+	PoolDedup map[string]string
+	Form      createForm // last submitted values (re-rendered after an error)
 }
 
 type datasetRow struct {
@@ -134,15 +136,18 @@ type datasetRow struct {
 }
 
 type createForm struct {
-	Pool, Name, Owner, Compression, Quota string
+	Pool, Name, Owner, Compression, Dedup, Quota string
 }
 
 func (s *Server) zfsView(st sched.Status, form createForm) zfsVM {
-	vm := zfsVM{S: st, Th: s.cfg.Get().Thresholds, Form: form}
+	vm := zfsVM{S: st, Th: s.cfg.Get().Thresholds, Form: form, PoolDedup: map[string]string{}}
 	if vm.Form.Owner == "" {
 		vm.Form.Owner = defaultOwner
 	}
 	for _, d := range st.Datasets {
+		if !strings.Contains(d.Name, "/") {
+			vm.PoolDedup[d.Name] = d.Dedup
+		}
 		row := datasetRow{Dataset: d, DomID: strings.NewReplacer("/", "-", ".", "_", ":", "_").Replace(d.Name)}
 		row.CanDestroy = strings.Contains(d.Name, "/") && d.Refer < zfsadm.EmptyRefer
 		for _, o := range st.Datasets {
@@ -170,6 +175,7 @@ func (s *Server) zfsCreate(w http.ResponseWriter, r *http.Request) {
 		Name:        strings.Trim(strings.TrimSpace(r.FormValue("name")), "/"),
 		Owner:       strings.TrimSpace(r.FormValue("owner")),
 		Compression: r.FormValue("compression"),
+		Dedup:       r.FormValue("dedup"),
 		Quota:       strings.ToUpper(strings.TrimSpace(r.FormValue("quota"))),
 	}
 	st := s.sch.Status()
@@ -191,20 +197,20 @@ func (s *Server) zfsCreate(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 	}
-	for _, err := range []error{zfsadm.ValidateOwner(f.Owner), zfsadm.ValidateCompression(f.Compression), zfsadm.ValidateSize(f.Quota)} {
+	for _, err := range []error{zfsadm.ValidateOwner(f.Owner), zfsadm.ValidateCompression(f.Compression), zfsadm.ValidateDedup(f.Dedup), zfsadm.ValidateSize(f.Quota)} {
 		if err != nil {
 			fail(err.Error())
 			return
 		}
 	}
-	err := s.admin.Create(full, zfsadm.CreateOpts{Compression: f.Compression, Quota: f.Quota, Owner: f.Owner})
+	err := s.admin.Create(full, zfsadm.CreateOpts{Compression: f.Compression, Dedup: f.Dedup, Quota: f.Quota, Owner: f.Owner})
 	s.sch.RefreshStorage()
 	if err != nil {
 		log.Printf("zfs create %s: %v", full, err)
 		fail(err.Error())
 		return
 	}
-	log.Printf("dataset %s created (owner %s, compression %q, quota %q)", full, f.Owner, f.Compression, f.Quota)
+	log.Printf("dataset %s created (owner %s, compression %q, dedup %q, quota %q)", full, f.Owner, f.Compression, f.Dedup, f.Quota)
 	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dataset "+full+" created")+"#"+url.PathEscape(f.Pool), http.StatusSeeOther)
 }
 
@@ -243,6 +249,37 @@ func (s *Server) zfsDestroy(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dataset "+name+" destroyed"), http.StatusSeeOther)
 }
 
+// zfsDedup turns dedup on/off on a pool's root dataset (inherited by children).
+func (s *Server) zfsDedup(w http.ResponseWriter, r *http.Request) {
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	pool := strings.TrimSpace(r.FormValue("pool"))
+	value := r.FormValue("dedup")
+	st := s.sch.Status()
+	fail := func(msg string) {
+		s.render(w, r, "zfs", pageData{Title: "ZFS", Data: s.zfsView(st, createForm{}), Alerts: len(st.Alerts), Error: "Dedup not changed: " + msg})
+	}
+	if !hasPool(st, pool) {
+		fail("unknown pool " + pool)
+		return
+	}
+	if value != "on" && value != "off" {
+		fail("dedup must be on or off")
+		return
+	}
+	err := s.admin.SetDedup(pool, value)
+	s.sch.RefreshStorage()
+	if err != nil {
+		log.Printf("zfs set dedup=%s %s: %v", value, pool, err)
+		fail(err.Error())
+		return
+	}
+	log.Printf("dedup=%s set on pool %s", value, pool)
+	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dedup "+value+" for "+pool)+"#"+url.PathEscape(pool), http.StatusSeeOther)
+}
+
 func hasPool(st sched.Status, name string) bool {
 	for _, p := range st.Pools {
 		if p.Name == name {