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

[Olga Kornievskaia <kolga@netapp.com>]

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(-)

-- 
1.8.3.1