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  1. 27 Sep, 2016 23 commits
  3. 23 Sep, 2016 3 commits
    • Daniel Wagner's avatar
      xprtrdma: use complete() instead complete_all() · 5690a22d
      Daniel Wagner authored 
      There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

The usage pattern of the completion is:

waiter context                          waker context

frwr_op_unmap_sync()
  reinit_completion()
  ib_post_send()
  wait_for_completion()

					frwr_wc_localinv_wake()
					  complete()
Signed-off-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: linux-nfs@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      5690a22d
    • Daniel Wagner's avatar
      NFS: cache_lib: use complete() instead of complete_all() · 2a446a5d
      Daniel Wagner authored 
      There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

The generic caching code from sunrpc is calling revisit() only once.

The usage pattern of the completion is:

waiter context                          waker context

do_cache_lookup_wait()
  nfs_cache_defer_req_alloc()
    init_completion()
  do_cache_lookup()
  nfs_cache_wait_for_upcall()
    wait_for_completion_timeout()

					nfs_dns_cache_revisit()
					  complete()

  nfs_cache_defer_req_put()
Signed-off-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      2a446a5d
    • Daniel Wagner's avatar
      NFS: direct: use complete() instead of complete_all() · 024de8f1
      Daniel Wagner authored 
      There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

nfs_file_direct_write() or nfs_file_direct_read() allocated a request
object via nfs_direct_req_alloc(), which initializes the
completion. The request object then is freed later in the exit path.
Between the initialization and the release either
nfs_direct_write_schedule_iovec() resp
nfs_direct_read_schedule_iovec() are called which will asynchronously
process the request. The calling function waits via nfs_direct_wait()
till the async work has been done. Thus there is only one waiter on
the completion.

nfs_direct_pgio_init() and nfs_direct_read_completion() are passed via
function pointers to nfs pageio. The first function does a ref
counting (get_dreq() and put_dreq()) which ensures that
nfs_direct_read_completion() and nfs_direct_read_schedule_iovec() only
call the completion path once.

The usage pattern of the completion is:

waiter context                          waker context

nfs_file_direct_write()
  dreq = nfs_direct_req_alloc()
    init_completion()
  nfs_direct_write_schedule_iovec()
  nfs_direct_wait()
    wait_for_completion_killable()

                                        nfs_direct_write_schedule_work()
                                          nfs_direct_complete()
                                            complete()

nfs_file_direct_read()
  dreq = nfs_direct_req_all()
    init_completion()
  nfs_direct_read_schedule_iovec()
  nfs_direct_wait()
    wait_for_completion_killable()
                                        nfs_direct_read_schedule_iovec()
                                          nfs_direct_complete()
                                            complete()

                                        nfs_direct_read_completion()
                                          nfs_direct_complete()
                                            complete()
Signed-off-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      024de8f1
  5. 22 Sep, 2016 12 commits
  7. 20 Sep, 2016 1 commit
  9. 19 Sep, 2016 1 commit
    • David Vrabel's avatar
      sunrpc: fix write space race causing stalls · d48f9ce7
      David Vrabel authored 
      Write space becoming available may race with putting the task to sleep
in xprt_wait_for_buffer_space().  The existing mechanism to avoid the
race does not work.

This (edited) partial trace illustrates the problem:

   [1] rpc_task_run_action: task:43546@5 ... action=call_transmit
   [2] xs_write_space <-xs_tcp_write_space
   [3] xprt_write_space <-xs_write_space
   [4] rpc_task_sleep: task:43546@5 ...
   [5] xs_write_space <-xs_tcp_write_space

[1] Task 43546 runs but is out of write space.

[2] Space becomes available, xs_write_space() clears the
    SOCKWQ_ASYNC_NOSPACE bit.

[3] xprt_write_space() attemts to wake xprt->snd_task (== 43546), but
    this has not yet been queued and the wake up is lost.

[4] xs_nospace() is called which calls xprt_wait_for_buffer_space()
    which queues task 43546.

[5] The call to sk->sk_write_space() at the end of xs_nospace() (which
    is supposed to handle the above race) does not call
    xprt_write_space() as the SOCKWQ_ASYNC_NOSPACE bit is clear and
    thus the task is not woken.

Fix the race by resetting the SOCKWQ_ASYNC_NOSPACE bit in xs_nospace()
so the second call to sk->sk_write_space() calls xprt_write_space().
Suggested-by: default avatarTrond Myklebust <trondmy@primarydata.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
cc: stable@vger.kernel.org # 4.4
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      d48f9ce7
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