NFS add session back channel draining

Currently session draining only drains the fore channel.
The back channel processing must also be drained.

Use the back channel highest_slot_used to indicate that a callback is being
processed by the callback thread.  Move the session complete to be per channel.

When the session is draininig, wait for any current back channel processing
to complete and stop all new back channel processing by returning NFS4ERR_DELAY
to the back channel client.

Drain the back channel, then the fore channel.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 25e8802a51d..b678e3e15bd 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -138,6 +138,8 @@ extern __be32 nfs4_callback_recallslot(struct cb_recallslotargs *args,
                                          void *dummy,
                                          struct cb_process_state *cps);
 
+extern void nfs4_check_drain_bc_complete(struct nfs4_session *ses);
+extern void nfs4_cb_take_slot(struct nfs_client *clp);
 #endif /* CONFIG_NFS_V4_1 */
 
 extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
@@ -145,7 +147,6 @@ extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
                                     struct cb_process_state *cps);
 extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy,
                                    struct cb_process_state *cps);
-
 #ifdef CONFIG_NFS_V4
 extern int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt);
 extern void nfs_callback_down(int minorversion);