nfsd41: control nfsv4.1 svc via /proc/fs/nfsd/versions

Support enabling and disabling nfsv4.1 via /proc/fs/nfsd/versions
by writing the strings "+4.1" or "-4.1" correspondingly.

Use user mode nfs-utils (rpc.nfsd option) to enable.
This will allow us to get rid of CONFIG_NFSD_V4_1

[nfsd41: disable support for minorversion by default]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 23 insertions, 3 deletions

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 4adebb6312c4..a9b8c75bf0bf 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -792,8 +792,9 @@ out_free:
 static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 {
         char *mesg = buf;
-        char *vers, sign;
+        char *vers, *minorp, sign;
         int len, num;
+        unsigned minor;
         ssize_t tlen = 0;
         char *sep;
 
@@ -814,9 +815,20 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
                 do {
                         sign = *vers;
                         if (sign == '+' || sign == '-')
-                                num = simple_strtol((vers+1), NULL, 0);
+                                num = simple_strtol((vers+1), &minorp, 0);
                         else
-                                num = simple_strtol(vers, NULL, 0);
+                                num = simple_strtol(vers, &minorp, 0);
+                        if (*minorp == '.') {
+                                if (num < 4)
+                                        return -EINVAL;
+                                minor = simple_strtoul(minorp+1, NULL, 0);
+                                if (minor == 0)
+                                        return -EINVAL;
+                                if (nfsd_minorversion(minor, sign == '-' ?
+                                                     NFSD_CLEAR : NFSD_SET) < 0)
+                                        return -EINVAL;
+                                goto next;
+                        }
                         switch(num) {
                         case 2:
                         case 3:
@@ -826,6 +838,7 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
                         default:
                                 return -EINVAL;
                         }
+                next:
                         vers += len + 1;
                         tlen += len;
                 } while ((len = qword_get(&mesg, vers, size)) > 0);
@@ -844,6 +857,13 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
                                        num);
                         sep = " ";
                 }
+        if (nfsd_vers(4, NFSD_AVAIL))
+                for (minor = 1; minor <= NFSD_SUPPORTED_MINOR_VERSION; minor++)
+                        len += sprintf(buf+len, " %c4.%u",
+                                        (nfsd_vers(4, NFSD_TEST) &&
+                                         nfsd_minorversion(minor, NFSD_TEST)) ?
+                                                '+' : '-',
+                                        minor);
         len += sprintf(buf+len, "\n");
         return len;
 }