nfs_common: prepare for the NFS client to use nfsd_file for LOCALIO

The next commit will introduce nfsd_open_local_fh() which returns an
nfsd_file structure.  This commit exposes LOCALIO's required NFSD
symbols to the NFS client:

- Make nfsd_open_local_fh() symbol and other required NFSD symbols
  available to NFS in a global 'nfs_to' nfsd_localio_operations
  struct (global access suggested by Trond, nfsd_localio_operations
  suggested by NeilBrown).  The next commit will also introduce
  nfsd_localio_ops_init() that init_nfsd() will call to initialize
  'nfs_to'.

- Introduce nfsd_file_file() that provides access to nfsd_file's
  backing file.  Keeps nfsd_file structure opaque to NFS client (as
  suggested by Jeff Layton).

- Introduce nfsd_file_put_local() that will put the reference to the
  nfsd_file's associated nn->nfsd_serv and then put the reference to
  the nfsd_file (as suggested by NeilBrown).

Suggested-by: Trond Myklebust <trond.myklebust@hammerspace.com> # nfs_to
Suggested-by: NeilBrown <neilb@suse.de> # nfsd_localio_operations
Suggested-by: Jeff Layton <jlayton@kernel.org> # nfsd_file_file
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

1 files changed, 26 insertions, 1 deletions

diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h
index 4165ff8390c1..1a39d7d727bd 100644
--- a/include/linux/nfslocalio.h
+++ b/include/linux/nfslocalio.h
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/uuid.h>
+#include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/svcauth.h>
 #include <linux/nfs.h>
 #include <net/net_namespace.h>
@@ -22,7 +23,7 @@
 typedef struct {
 	uuid_t uuid;
 	struct list_head list;
-	struct net *net; /* nfsd's network namespace */
+	struct net __rcu *net; /* nfsd's network namespace */
 	struct auth_domain *dom; /* auth_domain for localio */
 } nfs_uuid_t;
 
@@ -33,4 +34,28 @@ void nfs_uuid_is_local(const uuid_t *, struct list_head *,
 void nfs_uuid_invalidate_clients(struct list_head *list);
 void nfs_uuid_invalidate_one_client(nfs_uuid_t *nfs_uuid);
 
+struct nfsd_file;
+
+/* localio needs to map filehandle -> struct nfsd_file */
+extern struct nfsd_file *
+nfsd_open_local_fh(struct net *, struct auth_domain *, struct rpc_clnt *,
+		   const struct cred *, const struct nfs_fh *,
+		   const fmode_t) __must_hold(rcu);
+
+struct nfsd_localio_operations {
+	bool (*nfsd_serv_try_get)(struct net *);
+	void (*nfsd_serv_put)(struct net *);
+	struct nfsd_file *(*nfsd_open_local_fh)(struct net *,
+						struct auth_domain *,
+						struct rpc_clnt *,
+						const struct cred *,
+						const struct nfs_fh *,
+						const fmode_t);
+	void (*nfsd_file_put_local)(struct nfsd_file *);
+	struct file *(*nfsd_file_file)(struct nfsd_file *);
+} ____cacheline_aligned;
+
+extern void nfsd_localio_ops_init(void);
+extern const struct nfsd_localio_operations *nfs_to;
+
 #endif  /* __LINUX_NFSLOCALIO_H */