docker volume plugin: add support for ChunkStreams VFS option and add options note

cmd/mountlib/mount.go

@@ -169,6 +169,7 @@ func init() {
 
 // Options for creating the mount
 type Options struct {
+	// when modifying these options, please make sure to update getMountOption in cmd/serve/docker/options.go
 	DebugFUSE          bool          `config:"debug_fuse"`
 	AllowNonEmpty      bool          `config:"allow_non_empty"`
 	AllowRoot          bool          `config:"allow_root"`

cmd/serve/docker/options.go

@@ -268,6 +268,9 @@ func getVFSOption(vfsOpt *vfscommon.Options, opt rc.Params, key string) (ok bool
 		vfsOpt.FastFingerprint, err = opt.GetBool(key)
 	case "vfs-disk-space-total-size":
 		err = getFVarP(&vfsOpt.DiskSpaceTotalSize, opt, key)
+	case "vfs-read-chunk-streams":
+		intVal, err = opt.GetInt64(key)
+		vfsOpt.ChunkStreams = int(intVal)
 
 	// unprefixed vfs options
 	case "no-modtime":

vfs/vfscommon/options.go

@@ -162,6 +162,7 @@ func init() {
 
 // Options is options for creating the vfs
 type Options struct {
+	// when modifying these options, please make sure to update getVFSOption in cmd/serve/docker/options.go
 	NoSeek             bool          `config:"no_seek"`        // don't allow seeking if set
 	NoChecksum         bool          `config:"no_checksum"`    // don't check checksums if set
 	ReadOnly           bool          `config:"read_only"`      // if set VFS is read only