[PATCH] knfsd: Allow run-time selection of NFS versions to export

Provide a file in the NFSD filesystem that allows setting and querying of
which version of NFS are being exported.  Changes are only allowed while no
server is running.

Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 2a99a0bf54f6..a0871b3efeb7 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -23,6 +23,7 @@
 #include <linux/seq_file.h>
 #include <linux/pagemap.h>
 #include <linux/init.h>
+#include <linux/string.h>
 
 #include <linux/nfs.h>
 #include <linux/nfsd_idmap.h>
@@ -35,6 +36,8 @@
 
 #include <asm/uaccess.h>
 
+unsigned int nfsd_versbits = ~0;
+
 /*
  *      We have a single directory with 9 nodes in it.
  */
@@ -50,8 +53,15 @@ enum {
         NFSD_List,
         NFSD_Fh,
         NFSD_Threads,
+        NFSD_Versions,
+        /*
+         * The below MUST come last.  Otherwise we leave a hole in nfsd_files[]
+         * with !CONFIG_NFSD_V4 and simple_fill_super() goes oops
+         */
+#ifdef CONFIG_NFSD_V4
         NFSD_Leasetime,
         NFSD_RecoveryDir,
+#endif
 };
 
 /*
@@ -66,8 +76,11 @@ static ssize_t write_getfd(struct file *file, char *buf, size_t size);
 static ssize_t write_getfs(struct file *file, char *buf, size_t size);
 static ssize_t write_filehandle(struct file *file, char *buf, size_t size);
 static ssize_t write_threads(struct file *file, char *buf, size_t size);
+static ssize_t write_versions(struct file *file, char *buf, size_t size);
+#ifdef CONFIG_NFSD_V4
 static ssize_t write_leasetime(struct file *file, char *buf, size_t size);
 static ssize_t write_recoverydir(struct file *file, char *buf, size_t size);
+#endif
 
 static ssize_t (*write_op[])(struct file *, char *, size_t) = {
         [NFSD_Svc] = write_svc,
@@ -79,8 +92,11 @@ static ssize_t (*write_op[])(struct file *, char *, size_t) = {
         [NFSD_Getfs] = write_getfs,
         [NFSD_Fh] = write_filehandle,
         [NFSD_Threads] = write_threads,
+        [NFSD_Versions] = write_versions,
+#ifdef CONFIG_NFSD_V4
         [NFSD_Leasetime] = write_leasetime,
         [NFSD_RecoveryDir] = write_recoverydir,
+#endif
 };
 
 static ssize_t nfsctl_transaction_write(struct file *file, const char __user *buf, size_t size, loff_t *pos)
@@ -343,6 +359,70 @@ static ssize_t write_threads(struct file *file, char *buf, size_t size)
         return strlen(buf);
 }
 
+static ssize_t write_versions(struct file *file, char *buf, size_t size)
+{
+        /*
+         * Format:
+         *   [-/+]vers [-/+]vers ...
+         */
+        char *mesg = buf;
+        char *vers, sign;
+        int len, num;
+        ssize_t tlen = 0;
+        char *sep;
+
+        if (size>0) {
+                if (nfsd_serv)
+                        return -EBUSY;
+                if (buf[size-1] != '\n')
+                        return -EINVAL;
+                buf[size-1] = 0;
+
+                vers = mesg;
+                len = qword_get(&mesg, vers, size);
+                if (len <= 0) return -EINVAL;
+                do {
+                        sign = *vers;
+                        if (sign == '+' || sign == '-')
+                                num = simple_strtol((vers+1), NULL, 0);
+                        else
+                                num = simple_strtol(vers, NULL, 0);
+                        switch(num) {
+                        case 2:
+                        case 3:
+                        case 4:
+                                if (sign != '-')
+                                        NFSCTL_VERSET(nfsd_versbits, num);
+                                else
+                                        NFSCTL_VERUNSET(nfsd_versbits, num);
+                                break;
+                        default:
+                                return -EINVAL;
+                        }
+                        vers += len + 1;
+                        tlen += len;
+                } while ((len = qword_get(&mesg, vers, size)) > 0);
+                /* If all get turned off, turn them back on, as
+                 * having no versions is BAD
+                 */
+                if ((nfsd_versbits & NFSCTL_VERALL)==0)
+                        nfsd_versbits = NFSCTL_VERALL;
+        }
+        /* Now write current state into reply buffer */
+        len = 0;
+        sep = "";
+        for (num=2 ; num <= 4 ; num++)
+                if (NFSCTL_VERISSET(NFSCTL_VERALL, num)) {
+                        len += sprintf(buf+len, "%s%c%d", sep,
+                                       NFSCTL_VERISSET(nfsd_versbits, num)?'+':'-',
+                                       num);
+                        sep = " ";
+                }
+        len += sprintf(buf+len, "\n");
+        return len;
+}
+
+#ifdef CONFIG_NFSD_V4
 extern time_t nfs4_leasetime(void);
 
 static ssize_t write_leasetime(struct file *file, char *buf, size_t size)
@@ -384,6 +464,7 @@ static ssize_t write_recoverydir(struct file *file, char *buf, size_t size)
         status = nfs4_reset_recoverydir(recdir);
         return strlen(buf);
 }
+#endif
 
 /*----------------------------------------------------------------------------*/
 /*
@@ -403,6 +484,7 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent)
                 [NFSD_List] = {"exports", &exports_operations, S_IRUGO},
                 [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR},
                 [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
+                [NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
 #ifdef CONFIG_NFSD_V4
                 [NFSD_Leasetime] = {"nfsv4leasetime", &transaction_ops, S_IWUSR|S_IRUSR},
                 [NFSD_RecoveryDir] = {"nfsv4recoverydir", &transaction_ops, S_IWUSR|S_IRUSR},