package fs

type PendingFS interface {
   FS
   TrackPending(on bool)               // turn on/off tracking; callable by multiple packages
   ListPending(kind uint) []PendingOp  // return recently pending ops
                                       // takes a set of |'d values, e.g. OpKindTop | OpKindFile
   Interrupt(op ...PendingOp) error    // interrupt one or more ops, if still pending
}

type PendingFile interface {
   File
   ListPending() []PendingOp           // return recently pending ops on the file
}

type PendingOp interface {
   Fn() string                         // "Open" etc
   Params() []interface{}              // all arguments
   Pathname() string                   // empty if not applicable
   String() string                     // summary suitable for logging
}

type InterruptError struct {...}       // returned by interrupted ops

const (
   OpKindFile uint = 1 << iota
   ...
)

package context // elsewhere?

type FS interface {
   fs.PendingFS
   WithContext(c Context, kind uint)   // cancellation interrupts all ops of 'kind'
}

type File interface {
   fs.PendingFile
   WithContext(c Context)              // cancellation interrupts all ops on the File
                                       // the context is preset if FS.WithContext got fs.OpKindFile | ...
}

afs := NewMyFs()
afs.TrackPending(true)
...
afl, err := afs.Open("myfile")
...
if problems {
   afs.Interrupt(afl.ListPending()...)
}