From a43cde94feded0f65fce36330614691c650ae8fe Mon Sep 17 00:00:00 2001 From: Ricardo Labiaga Date: Wed, 1 Apr 2009 09:23:08 -0400 Subject: nfs41: Implement NFSv4.1 callback service process. nfs41_callback_up() initializes the necessary queues and creates the new nfs41_callback_svc thread. This thread executes the callback service which waits for requests to arrive on the svc_serv->sv_cb_list. NFS41_BC_MIN_CALLBACKS is set to 1 because we expect callbacks to not cause substantial latency. The actual processing of the callback will be implemented as a separate patch. There is only one NFSv4.1 callback service. The first caller of nfs4_callback_up() creates the service, subsequent callers increment a reference count on the service. The service is destroyed when the last caller invokes nfs_callback_down(). The transport needs to hold a reference to the callback service in order to invoke it during callback processing. Currently this reference is only obtained when the service is first created. This is incorrect, since subsequent registrations for other transports will leave the xprt->serv pointer uninitialized, leading to an oops when a callback arrives on the "unreferenced" transport. This patch fixes the problem by ensuring that a reference to the service is saved in xprt->serv, either because the service is created by this invocation to nfs4_callback_up() or by a prior invocation. Signed-off-by: Ricardo Labiaga Signed-off-by: Benny Halevy [nfs41: Add a reference to svc_serv during callback service bring up] Signed-off-by: Ricardo Labiaga Signed-off-by: Benny Halevy [Type check arguments of nfs_callback_up] Signed-off-by: Ricardo Labiaga Signed-off-by: Benny Halevy [nfs41: save svc_serv in nfs_callback_info] Signed-off-by: Benny Halevy [Removal of ugly #ifdefs] [nfs41: Update to removal of ugly #ifdefs] Signed-off-by: Ricardo Labiaga Signed-off-by: Benny Halevy --- fs/nfs/callback.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/nfs/callback.h') diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h index 9b907f408b8..29123b5604f 100644 --- a/fs/nfs/callback.h +++ b/fs/nfs/callback.h @@ -70,6 +70,13 @@ extern void nfs_callback_down(void); #define nfs_callback_down() do {} while(0) #endif +/* + * nfs41: Callbacks are expected to not cause substantial latency, + * so we limit their concurrency to 1 by setting up the maximum number + * of slots for the backchannel. + */ +#define NFS41_BC_MIN_CALLBACKS 1 + extern unsigned int nfs_callback_set_tcpport; extern unsigned short nfs_callback_tcpport; extern unsigned short nfs_callback_tcpport6; -- cgit v1.2.3