[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 2a99a0b..a0871b3 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},