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, 28 insertions, 0 deletions

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index caeffc43ca4b..414b5bf738df 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -390,6 +390,34 @@ nfsd_file_put(struct nfsd_file *nf)
 		nfsd_file_free(nf);
 }
 
+/**
+ * nfsd_file_put_local - put the reference to nfsd_file and local nfsd_serv
+ * @nf: nfsd_file of which to put the references
+ *
+ * First put the reference of the nfsd_file and then put the
+ * reference to the associated nn->nfsd_serv.
+ */
+void
+nfsd_file_put_local(struct nfsd_file *nf)
+{
+	struct net *net = nf->nf_net;
+
+	nfsd_file_put(nf);
+	nfsd_serv_put(net);
+}
+
+/**
+ * nfsd_file_file - get the backing file of an nfsd_file
+ * @nf: nfsd_file of which to access the backing file.
+ *
+ * Return backing file for @nf.
+ */
+struct file *
+nfsd_file_file(struct nfsd_file *nf)
+{
+	return nf->nf_file;
+}
+
 static void
 nfsd_file_dispose_list(struct list_head *dispose)
 {