weed/shell: resolve collection from topology when ec.decode is given only volumeId (#12424)

* weed/shell: resolve collection from topology when ec.decode is given only volumeId

When ec.decode is invoked with -volumeId for a volume that belongs to a named collection without explicitly specifying -collection, DoEcDecode was called with an empty collection string. Target volume servers then rejected VolumeEcShardsCopy with 'CopyFile not found ec volume id <vid>' because they looked under the default collection.

This commit introduces FindEcVolumeCollection to discover the collection name directly from topology metadata (checking EC shard info and regular volume info), ensuring DoEcDecode receives the accurate collection.

* ec.decode: resolve every batch volume's collection from the topology

The batch passed -collection through unless it looked like a regex, so a
comma list (a,b), a {n} quantifier, ALL or _default_ reached the volume
servers as a collection name and the copy found no shards. The selector
only picks the volumes; each one is decoded in its own collection.

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

* ec.decode: take the collection only from the volume's ec shards

The lookup returned the first record per disk, so a regular volume on an
earlier node answered before the ec shards on a later one. A decode needs
the shards anyway, so their records are the only ones to read.

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

* ec.decode: leave the -volumeId lookup to DoEcDecode

DoEcDecode already resolves an empty collection from the topology.

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

---------

Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

weed/ec/ec_decode.go

@@ -26,6 +26,12 @@ func DoEcDecode(env *Env, topoInfo *master_pb.TopologyInfo, collection string, v
 		return fmt.Errorf("lock is lost")
 	}
 
+	if collection == "" {
+		if c, found := FindEcVolumeCollection(topoInfo, vid); found {
+			collection = c
+		}
+	}
+
 	// find volume location
 	nodeToEcShardsInfo, dataShards := collectEcNodeShardsInfo(topoInfo, vid)
 
@@ -376,6 +382,33 @@ func CollectEcShardIds(topoInfo *master_pb.TopologyInfo, collectionMatcher *wild
 	return
 }
 
+// FindEcVolumeCollection returns the collection of the ec volume's shards.
+func FindEcVolumeCollection(topoInfo *master_pb.TopologyInfo, vid needle.VolumeId) (string, bool) {
+	if topoInfo == nil {
+		return "", false
+	}
+	var collection string
+	var found bool
+	EachDataNode(topoInfo, func(dc DataCenterId, rack RackId, dn *master_pb.DataNodeInfo) {
+		if found {
+			return
+		}
+		for _, diskInfo := range dn.DiskInfos {
+			if diskInfo == nil {
+				continue
+			}
+			for _, v := range diskInfo.EcShardInfos {
+				if v.Id == uint32(vid) {
+					collection = v.Collection
+					found = true
+					return
+				}
+			}
+		}
+	})
+	return collection, found
+}
+
 func collectEcNodeShardsInfo(topoInfo *master_pb.TopologyInfo, vid needle.VolumeId) (map[pb.ServerAddress]*erasure_coding.ShardsInfo, int) {
 	res := make(map[pb.ServerAddress]*erasure_coding.ShardsInfo)
 	EachDataNode(topoInfo, func(dc DataCenterId, rack RackId, dn *master_pb.DataNodeInfo) {

weed/ec/ec_decode_test.go

@@ -4,7 +4,9 @@ import (
 	"testing"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
 	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
 )
 
 // shardsOn builds one holder's inventory.
@@ -89,3 +91,99 @@ func TestMissingDataShard(t *testing.T) {
 		})
 	}
 }
+
+func TestFindEcVolumeCollection(t *testing.T) {
+	topo := &master_pb.TopologyInfo{
+		DataCenterInfos: []*master_pb.DataCenterInfo{
+			{
+				Id: "dc1",
+				RackInfos: []*master_pb.RackInfo{
+					{
+						Id: "rack1",
+						DataNodeInfos: []*master_pb.DataNodeInfo{
+							{
+								Id: "node1",
+								DiskInfos: map[string]*master_pb.DiskInfo{
+									"hdd": {
+										EcShardInfos: []*master_pb.VolumeEcShardInformationMessage{
+											{
+												Id:         10,
+												Collection: "s3bucket",
+											},
+											{
+												Id:         30,
+												Collection: "",
+											},
+										},
+										VolumeInfos: []*master_pb.VolumeInformationMessage{
+											{
+												Id:         20,
+												Collection: "regular_col",
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	tests := []struct {
+		name      string
+		topo      *master_pb.TopologyInfo
+		vid       needle.VolumeId
+		wantCol   string
+		wantFound bool
+	}{
+		{
+			name:      "nil topology",
+			topo:      nil,
+			vid:       10,
+			wantCol:   "",
+			wantFound: false,
+		},
+		{
+			name:      "ec volume with named collection",
+			topo:      topo,
+			vid:       10,
+			wantCol:   "s3bucket",
+			wantFound: true,
+		},
+		{
+			name:      "ec volume with empty collection",
+			topo:      topo,
+			vid:       30,
+			wantCol:   "",
+			wantFound: true,
+		},
+		{
+			name:      "regular volume record is not an ec volume",
+			topo:      topo,
+			vid:       20,
+			wantCol:   "",
+			wantFound: false,
+		},
+		{
+			name:      "not found",
+			topo:      topo,
+			vid:       999,
+			wantCol:   "",
+			wantFound: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			col, found := FindEcVolumeCollection(tt.topo, tt.vid)
+			if found != tt.wantFound {
+				t.Fatalf("FindEcVolumeCollection() found = %v, want %v", found, tt.wantFound)
+			}
+			if col != tt.wantCol {
+				t.Errorf("FindEcVolumeCollection() col = %q, want %q", col, tt.wantCol)
+			}
+		})
+	}
+}

weed/shell/command_ec_decode.go

@@ -113,7 +113,9 @@ func (c *commandEcDecode) Do(args []string, commandEnv *CommandEnv, writer io.Wr
 			fmt.Printf("ec decode batch %d/%d: %v\n", i+1, len(batches), batch)
 		}
 		for _, vid := range batch {
-			if err = ec.DoEcDecode(env, topologyInfo, *collection, vid, diskType, *checkMinFreeSpace, diskUsageState); err != nil {
+			// -collection is a selector, not the volume's collection
+			volumeCollection, _ := ec.FindEcVolumeCollection(topologyInfo, vid)
+			if err = ec.DoEcDecode(env, topologyInfo, volumeCollection, vid, diskType, *checkMinFreeSpace, diskUsageState); err != nil {
 				return err
 			}
 		}