nfsd: add notifier to handle mount/unmount of rpc_pipefs sb

In the event that rpc_pipefs isn't mounted when nfsd starts, we
must register a notifier to handle creating the dentry once it
is mounted, and to remove the dentry on unmount.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index cec62ed2a064..6f13281635ba 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -38,6 +38,7 @@
 #include <linux/crypto.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
+#include <linux/module.h>
 #include <net/net_namespace.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
 #include <linux/sunrpc/clnt.h>
@@ -982,3 +983,46 @@ nfsd4_record_grace_done(struct net *net, time_t boot_time)
         if (client_tracking_ops)
                 client_tracking_ops->grace_done(net, boot_time);
 }
+
+static int
+rpc_pipefs_event(struct notifier_block *nb, unsigned long event, void *ptr)
+{
+        struct super_block *sb = ptr;
+        struct net *net = sb->s_fs_info;
+        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+        struct cld_net *cn = nn->cld_net;
+        struct dentry *dentry;
+        int ret = 0;
+
+        if (!try_module_get(THIS_MODULE))
+                return 0;
+
+        if (!cn) {
+                module_put(THIS_MODULE);
+                return 0;
+        }
+
+        switch (event) {
+        case RPC_PIPEFS_MOUNT:
+                dentry = nfsd4_cld_register_sb(sb, cn->cn_pipe);
+                if (IS_ERR(dentry)) {
+                        ret = PTR_ERR(dentry);
+                        break;
+                }
+                cn->cn_pipe->dentry = dentry;
+                break;
+        case RPC_PIPEFS_UMOUNT:
+                if (cn->cn_pipe->dentry)
+                        nfsd4_cld_unregister_sb(cn->cn_pipe);
+                break;
+        default:
+                ret = -ENOTSUPP;
+                break;
+        }
+        module_put(THIS_MODULE);
+        return ret;
+}
+
+struct notifier_block nfsd4_cld_block = {
+        .notifier_call = rpc_pipefs_event,
+};