knfsd: clean up nfsd filesystem interfaces

Several of the nfsd filesystem interfaces allow changes to parameters
that don't have any effect on a running nfsd service. They are only ever
checked when nfsd is started. This patch fixes it so that changes to
those procfiles return -EBUSY if nfsd is already running to make it
clear that changes on the fly don't work.

The patch should also close some relatively harmless races between
changing the info in those interfaces and starting nfsd, since these
variables are being moved under the protection of the nfsd_mutex.

Finally, the nfsv4recoverydir file always returns -EINVAL if read. This
patch fixes it to return the recoverydir path as expected.

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

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 5c97d47676ae..bf11d6879ab4 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3249,12 +3249,14 @@ nfs4_state_shutdown(void)
 	nfs4_unlock_state();
 }
 
+/*
+ * user_recovery_dirname is protected by the nfsd_mutex since it's only
+ * accessed when nfsd is starting.
+ */
 static void
 nfs4_set_recdir(char *recdir)
 {
-	nfs4_lock_state();
 	strcpy(user_recovery_dirname, recdir);
-	nfs4_unlock_state();
 }
 
 /*
@@ -3278,6 +3280,12 @@ nfs4_reset_recoverydir(char *recdir)
 	return status;
 }
 
+char *
+nfs4_recoverydir(void)
+{
+	return user_recovery_dirname;
+}
+
 /*
  * Called when leasetime is changed.
  *
@@ -3286,11 +3294,12 @@ nfs4_reset_recoverydir(char *recdir)
  * we start to register any changes in lease time.  If the administrator
  * really wants to change the lease time *now*, they can go ahead and bring
  * nfsd down and then back up again after changing the lease time.
+ *
+ * user_lease_time is protected by nfsd_mutex since it's only really accessed
+ * when nfsd is starting
  */
 void
 nfs4_reset_lease(time_t leasetime)
 {
-	lock_kernel();
 	user_lease_time = leasetime;
-	unlock_kernel();
 }