On Thu, Sep 28, 2017 at 03:04:13PM -0400, Olga Kornievskaia wrote: > > > On Sep 28, 2017, at 2:55 PM, J. Bruce Fields <bfields@xxxxxxxxxx> wrote: > > > > On Thu, Sep 28, 2017 at 02:44:42PM -0400, Olga Kornievskaia wrote: > >> > >>> On Sep 28, 2017, at 2:07 PM, J. Bruce Fields <bfields@xxxxxxxxxx> wrote: > >>> > >>> On Thu, Sep 28, 2017 at 01:29:40PM -0400, Olga Kornievskaia wrote: > >>>> Asynchronous copies are handled by a single threaded workqueue. > >>>> If we get asynchronous request, make sure to copy the needed > >>>> arguments/state from the stack before starting the copy. Then > >>>> queue work and reply back to the client indicating copy is > >>>> asynchronous. > >>>> > >>>> nfsd_copy_file_range() will copy in 4MBchunk so do a loop over > >>>> the total number of bytes need to copy. > >>> > >>> I don't think you need to do this--just call vfs_copy_file_range() > >>> directly, as nfsd_copy_file_range does. > >>> > >>> The 4MB chunking was only there to prevent a synchronous copy from > >>> taking too long, which isn't an issue in the async case. > >>> > >> > >> One reason is to allow for the copy to be cancelled in the “middle”. > >> Otherwise, we have no control over once we call into the vfs_copy_file_range > >> to stop the on-going copy. At least this way we check every 4MB chunks. > > > > Yes, see my other email, I think we should signal the thread to stop it. > > > > Even with copying in chunks--we'd like to be able to cancel the copy > > mid-chunk. > > > > Talking this over here with Jeff and Trond.... I don't *think* there's > > an easy way to cancel a long-running work item. > > Yes I believe I was looking into signaling but couldn’t figure out how to do it > with the current code... > > > So probably you want to create your own thread for the copy instead. It > > looks like kthread_create/kthread_stop/kthread_should_stop are what you > > want? You can see some examples if you "git grep kthread net/sunrpc”. > > Ok so should I instead create a dedicated thread to do all copies and have > a way to give this thread work? Or are you ok with creating a thread for > each individual copy which would be much simpler? I'd be in favor of a thread per copy. That should make the cancelling either as well. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
