Re: [PATCH v6 00/10] NFSD support for asynchronous COPY

[Olga Kornievskaia <aglo@umich.edu>]

On Tue, Oct 24, 2017 at 1:47 PM, Olga Kornievskaia <kolga@netapp.com> wrote:
> To do asynchronous copies, NFSD creates a new kthread to handle the request.
> Upon receiving the COPY, it generates a unique copy stateid (stored in a
> global list for keeping track of state for OFFLOAD_STATUS to be queried by),
> starts the thread, and replies back to the client. nfsd4_copy arguments that
> are allocated on the stack are copies for the kthread.
>
> For the async copy handler, copy is done in the loop for the requested
> number of bytes. If an error is encountered and partial copy has happened,
> a successful partial copy is returned in the CB_OFFLOAD. vfs_copy_file_range
> is called with 4MB chunks for both async and sync, allowing for 4MB
> granularity of OFFLOAD_STATUS queiry. Once copy is done, the results are
> queued for the callback workqueue and sent via CB_OFFLOAD.
>
> When the server received an OFFLOAD_CANCEL, it will find the kthread running
> the copy and will send a SIGPENDING and kthread_stop() and it will interrupt
> the ongoing do_splice() and once vfs returns we are choosing not to send
> the CB_OFFLOAD back to the client.
>
> When the server receives an OFFLOAD_STATUS, it will find the kthread running
> the copy and will locate within the copy state the current number of bytes
> copied so far.
>
> v6:
> 1. if an error occured and partial bytes were copied, don't return the error
> and instead return the successful partial copy.
> 2. OFFLOAD_STATUS locates the on-going copy and looks up the number of bytes
> copied so far.
>
> Olga Kornievskaia (10):
>   NFSD CB_OFFLOAD xdr
>   NFSD OFFLOAD_STATUS xdr
>   NFSD OFFLOAD_CANCEL xdr
>   NFSD xdr callback stateid in async COPY reply
>   NFSD first draft of async copy
>   NFSD return nfs4_stid in nfs4_preprocess_stateid_op
>   NFSD create new stateid for async copy
>   NFSD handle OFFLOAD_CANCEL op
>   NFSD support OFFLOAD_STATUS
>   NFSD stop queued async copies on client shutdown
>
>  fs/nfsd/netns.h        |   8 ++
>  fs/nfsd/nfs4callback.c |  97 +++++++++++++++
>  fs/nfsd/nfs4proc.c     | 316 ++++++++++++++++++++++++++++++++++++++++++++-----
>  fs/nfsd/nfs4state.c    |  77 +++++++++++-
>  fs/nfsd/nfs4xdr.c      |  50 ++++++--
>  fs/nfsd/nfsctl.c       |   1 +
>  fs/nfsd/state.h        |  21 +++-
>  fs/nfsd/xdr4.h         |  28 +++++
>  fs/nfsd/xdr4cb.h       |  10 ++
>  9 files changed, 571 insertions(+), 37 deletions(-)

Bruce, any comments on this version?