nfsd4: don't sleep in lease-break callback

The NFSv4 server's fl_break callback can sleep (dropping the BKL), in
order to allocate a new rpc task to send a recall to the client.

As far as I can tell this doesn't cause any races in the current code,
but the analysis is difficult.  Also, the sleep here may complicate the
move away from the BKL.

So, just schedule some work to do the job for us instead.  The work will
later also prove useful for restarting a call after the callback
information is changed.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index b85437982a8..c4c92aea8f3 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -77,6 +77,7 @@ struct nfs4_rpc_args {
 
 struct nfsd4_callback {
         struct nfs4_rpc_args cb_args;
+        struct work_struct cb_work;
 };
 
 struct nfs4_delegation {
@@ -391,7 +392,11 @@ extern void put_nfs4_client(struct nfs4_client *clp);
 extern void nfs4_free_stateowner(struct kref *kref);
 extern int set_callback_cred(void);
 extern void nfsd4_probe_callback(struct nfs4_client *clp);
+extern void nfsd4_do_callback_rpc(struct work_struct *);
 extern void nfsd4_cb_recall(struct nfs4_delegation *dp);
+extern int nfsd4_create_callback_queue(void);
+extern void nfsd4_destroy_callback_queue(void);
+extern void nfsd4_set_callback_client(struct nfs4_client *, struct rpc_clnt *);
 extern void nfs4_put_delegation(struct nfs4_delegation *dp);
 extern __be32 nfs4_make_rec_clidname(char *clidname, struct xdr_netobj *clname);
 extern void nfsd4_init_recdir(char *recdir_name);