NFSD introduce async copy feature

Upon receiving a request for async copy, create a new kthread.  If we
get asynchronous request, make sure to copy the needed arguments/state
from the stack before starting the copy. Then start the thread and reply
back to the client indicating copy is asynchronous.

nfsd_copy_file_range() will copy in a loop over the total number of
bytes is needed to copy. In case a failure happens in the middle, we
ignore the error and return how much we copied so far. Once done
creating a workitem for the callback workqueue and send CB_OFFLOAD with
the results.

The lifetime of the copy stateid is bound to the vfs copy. This way we
don't need to keep the nfsd_net structure for the callback.  We could
keep it around longer so that an OFFLOAD_STATUS that came late would
still get results, but clients should be able to deal without that.

We handle OFFLOAD_CANCEL by sending a signal to the copy thread and
calling kthread_stop.

A client should cancel any ongoing copies before calling DESTROY_CLIENT;
if not, we return a CLIENT_BUSY error.

If the client is destroyed for some other reason (lease expiration, or
server shutdown), we must clean up any ongoing copies ourselves.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
[colin.king@canonical.com: fix leak in error case]
[bfields@fieldses.org: remove signalling, merge patches]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 7fb9f7c667b1..6384c9b94898 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1242,6 +1242,7 @@ static __net_init int nfsd_init_net(struct net *net)
 	nn->somebody_reclaimed = false;
 	nn->clverifier_counter = prandom_u32();
 	nn->clientid_counter = prandom_u32();
+	nn->s2s_cp_cl_id = nn->clientid_counter++;
 
 	atomic_set(&nn->ntf_refcnt, 0);
 	init_waitqueue_head(&nn->ntf_wq);