feat(agent): report btrfs filesystems as storage pools (#2315)

Co-authored-by: henrygd <hank@henrygd.me>

internal/entities/zfs/zfs.go

@@ -1,23 +1,47 @@
 // Package zfs defines the ZFS detail data exchanged between agent and hub.
 package zfs
 
+import "strings"
+
 // ZfsData is the detail payload returned by the agent for the GetZfsData action.
 type ZfsData struct {
 	Pools    []*PoolDetail `json:"pools,omitempty"`
 	Complete bool          `json:"complete,omitempty"`
+	// Backends whose inventories are complete, even when another backend failed.
+	CompleteBackends []string `json:"completeBackends,omitempty"`
+}
+
+// CanRefreshPool also governs deletion: missing pools may only be removed
+// after a successful inventory of their backend. Complete supports old agents.
+func (data *ZfsData) CanRefreshPool(name string) bool {
+	if data.Complete {
+		return true
+	}
+	backend := "zfs"
+	if strings.HasPrefix(name, "b:") {
+		backend = "btrfs"
+	}
+	for _, complete := range data.CompleteBackends {
+		if complete == backend {
+			return true
+		}
+	}
+	return false
 }
 
 // PoolDetail holds the verbose state of a single pool: capacity, health,
 // scrub, vdev, and dataset information.
 type PoolDetail struct {
-	Name     string     `json:"name"`
-	Health   string     `json:"health,omitempty"`
-	Size     uint64     `json:"size,omitempty"`  // bytes
-	Alloc    uint64     `json:"alloc,omitempty"` // bytes
-	Free     uint64     `json:"free,omitempty"`  // bytes
-	Scrub    *Scrub     `json:"scrub,omitempty"`
-	Vdevs    []*Vdev    `json:"vdevs,omitempty"`
-	Datasets []*Dataset `json:"datasets,omitempty"`
+	DisplayName string     `json:"displayName,omitempty"`
+	Raw         bool       `json:"raw,omitempty"`
+	Name        string     `json:"name"`
+	Health      string     `json:"health,omitempty"`
+	Size        uint64     `json:"size,omitempty"`  // bytes
+	Alloc       uint64     `json:"alloc,omitempty"` // bytes
+	Free        uint64     `json:"free,omitempty"`  // bytes
+	Scrub       *Scrub     `json:"scrub,omitempty"`
+	Vdevs       []*Vdev    `json:"vdevs,omitempty"`
+	Datasets    []*Dataset `json:"datasets,omitempty"`
 }
 
 // Scrub holds the scrub (or resilver) status of a pool.