fix(shell): scope volume.fsck filer walk when -volumeId selects one bucketed collection (#9347)

* fix(shell): scope volume.fsck filer walk to the bucket when -volumeId selects one bucketed collection

Closes #9345.

-volumeId only filtered which volume .idx files were pulled; the filer-side
BFS still walked from "/", printing every directory under -v and making it
look like the flag was ignored. When all requested volumes share a single
non-empty collection that maps to an existing <bucketsPath>/<collection>
directory, restrict the BFS root to that bucket. Empty-collection volumes
or multi-collection selections fall back to the full walk, since chunks
for those can live anywhere.

* trim comments

* address review: collapse getCollectFilerFilePath; unshadow receiver in loop

weed/shell/command_volume_fsck.go

@@ -52,6 +52,7 @@ type commandVolumeFsck struct {
 	bucketsPath               string
 	collection                *string
 	volumeIds                 map[uint32]bool
+	scopedFilerPath           string
 	tempFolder                string
 	verbose                   *bool
 	forcePurging              *bool
@@ -185,6 +186,11 @@ func (c *commandVolumeFsck) Do(args []string, commandEnv *CommandEnv, writer io.
 		}
 	}
 
+	c.scopedFilerPath = c.resolveScopedFilerPath(dataNodeVolumeIdToVInfo)
+	if *c.verbose && c.scopedFilerPath != "/" {
+		fmt.Fprintf(c.writer, "scoping filer walk to %s\n", c.scopedFilerPath)
+	}
+
 	var collectCutoffFromAtNs int64 = 0
 	if cutoffTimeAgo.Seconds() != 0 {
 		collectCutoffFromAtNs = time.Now().Add(-*cutoffTimeAgo).UnixNano()
@@ -854,10 +860,65 @@ func (c *commandVolumeFsck) purgeFileIdsForOneVolume(volumeId uint32, fileIds []
 }
 
 func (c *commandVolumeFsck) getCollectFilerFilePath() string {
+	return c.scopedFilerPath
+}
+
+func (c *commandVolumeFsck) resolveScopedFilerPath(dataNodeVolumeIdToVInfo map[string]map[uint32]VInfo) string {
 	if *c.collection != "" {
 		return fmt.Sprintf("%s/%s", c.bucketsPath, *c.collection)
 	}
-	return "/"
+	if len(c.volumeIds) == 0 {
+		return "/"
+	}
+	collections := make(map[string]struct{})
+	for _, vidMap := range dataNodeVolumeIdToVInfo {
+		for vid, vinfo := range vidMap {
+			if _, ok := c.volumeIds[vid]; !ok {
+				continue
+			}
+			// empty collection: volume can be referenced from anywhere
+			if vinfo.collection == "" {
+				return "/"
+			}
+			collections[vinfo.collection] = struct{}{}
+			if len(collections) > 1 {
+				return "/"
+			}
+		}
+	}
+	if len(collections) != 1 {
+		return "/"
+	}
+	var collection string
+	for col := range collections {
+		collection = col
+	}
+	exists, err := c.bucketDirExists(collection)
+	if err != nil || !exists {
+		return "/"
+	}
+	return fmt.Sprintf("%s/%s", c.bucketsPath, collection)
+}
+
+func (c *commandVolumeFsck) bucketDirExists(name string) (bool, error) {
+	var found bool
+	err := c.env.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
+		resp, err := client.LookupDirectoryEntry(context.Background(), &filer_pb.LookupDirectoryEntryRequest{
+			Directory: c.bucketsPath,
+			Name:      name,
+		})
+		if err != nil {
+			if strings.Contains(err.Error(), filer_pb.ErrNotFound.Error()) {
+				return nil
+			}
+			return err
+		}
+		if resp.Entry != nil && resp.Entry.IsDirectory {
+			found = true
+		}
+		return nil
+	})
+	return found, err
 }
 
 func getVolumeFileIdFile(tempFolder string, dataNodeid string, vid uint32) string {