[PATCH 01/10] nfsd: persist nfsd filesystem across mounts

["J. Bruce Fields" <bfields@redhat.com>]

From: "J. Bruce Fields" <bfields@redhat.com>

Keep around one internal mount of the nfsd filesystem so that we can
e.g. add stuff to it when clients come and go, regardless of whether
anyone has it mounted.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/netns.h  |  3 +++
 fs/nfsd/nfsctl.c | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 32cb8c027483..cce335e1ec98 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -55,6 +55,9 @@ struct nfsd_net {
 	bool grace_ended;
 	time_t boot_time;
 
+	/* internal mount of the "nfsd" pseudofilesystem: */
+	struct vfsmount *nfsd_mnt;
+
 	/*
 	 * reclaim_str_hashtbl[] holds known client info from previous reset/reboot
 	 * used in reboot/reset lease grace period processing
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index f2feb2d11bae..8d2062428569 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1231,6 +1231,7 @@ unsigned int nfsd_net_id;
 static __net_init int nfsd_init_net(struct net *net)
 {
 	int retval;
+	struct vfsmount *mnt;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
 	retval = nfsd_export_init(net);
@@ -1248,8 +1249,17 @@ static __net_init int nfsd_init_net(struct net *net)
 
 	atomic_set(&nn->ntf_refcnt, 0);
 	init_waitqueue_head(&nn->ntf_wq);
+
+	mnt =  vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);
+	if (IS_ERR(mnt)) {
+		retval = PTR_ERR(mnt);
+		goto out_mount_err;
+	}
+	nn->nfsd_mnt = mnt;
 	return 0;
 
+out_mount_err:
+	nfsd_idmap_shutdown(net);
 out_idmap_error:
 	nfsd_export_shutdown(net);
 out_export_error:
@@ -1258,6 +1268,9 @@ static __net_init int nfsd_init_net(struct net *net)
 
 static __net_exit void nfsd_exit_net(struct net *net)
 {
+	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+
+	mntput(nn->nfsd_mnt);
 	nfsd_idmap_shutdown(net);
 	nfsd_export_shutdown(net);
 }
-- 
2.20.1