On Thu, Sep 28, 2017 at 3:07 PM, J. Bruce Fields <bfields@xxxxxxxxxx> wrote: > 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. ok thanks. will work on that. -- 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
