nfsd: formally deprecate legacy nfsd syscall interface

The syscall interface is has been replaced by a more flexible
interface since 2.6.0.  It is time to work towards discarding
the old interface.

So add a entry in feature-removal-schedule.txt and print a warning
when the interface is used.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 842aa9de84a6..076a2c02adaf 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -564,3 +564,13 @@ Who:	FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 
 ----------------------------
 
+What:   access to nfsd auth cache through sys_nfsservctl or '.' files
+        in the 'nfsd' filesystem.
+When:   2.6.40
+Why:    This is a legacy interface which have been replaced by a more
+        dynamic cache.  Continuing to maintain this interface is an
+        unnecessary burden.
+Who:    NeilBrown <neilb@suse.de>
+
+----------------------------
+        
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index b53b1d042f1f..7f0fc8861b85 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -121,6 +121,16 @@ static ssize_t nfsctl_transaction_write(struct file *file, const char __user *bu
 
 static ssize_t nfsctl_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
 {
+        static int warned;
+        if (file->f_dentry->d_name.name[0] == '.' && !warned) {
+                char name[sizeof(current->comm)];
+                printk(KERN_INFO
+                       "Warning: \"%s\" uses deprecated NFSD interface: %s."
+                       "  This will be removed in 2.6.40\n",
+                       get_task_comm(name, current),
+                       file->f_dentry->d_name.name);
+                warned = 1;
+        }
         if (! file->private_data) {
                 /* An attempt to read a transaction file without writing
                  * causes a 0-byte write so that the file can return