text-based mount.nfs: Fix mounthost= processing

The 'mounthost=' option names a host where the mountd service is running.
The option is used to direct clients to use a different host for the mountd
procotol than the host where the NFS service is running.

The nfs(5) man page shows that the 'mounthost=' option takes a name, not
an address.  The kernel's text-based mount option parsing logic expects an
IPv4 address.  This is necessary because the kernel cannot itself resolve
hostnames to addresses.

Resolve the hostname and pass in a new mount option that contains the
resolved address, 'mountaddr=', to the kernel.

This requires a patch to the kernel to recognize the new 'mountaddr='
option, and to change the 'mounthost=' parsing logic to treat the value of
this option as a simple string.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Neil Brown <neilb@suse.de>

diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index e3a3ac941d322c55950f7347a0b3f26154d71941..b31b3a28e20cc7a0ed9a7c2422f7d33ce19364aa 100644 (file)
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -190,6 +190,30 @@ static int append_clientaddr_option(struct sockaddr_in *saddr,
        return 0;
 }
 
+/*
+ * Called to resolve the 'mounthost=' hostname and append a new
+ * option using an IPv4 address.
+ */
+static int fix_up_mounthost_opt(struct mount_options *options)
+{
+       struct sockaddr_in maddr;
+       char *mounthost, new_option[32];
+
+       mounthost = po_get(options, "mounthost");
+       if (!mounthost)
+               return 1;
+
+       if (!fill_ipv4_sockaddr(mounthost, &maddr))
+               return 0;
+
+       snprintf(new_option, sizeof(new_option) - 1,
+                       "mountaddr=%s", inet_ntoa(maddr.sin_addr));
+
+       if (po_append(options, new_option) == PO_SUCCEEDED)
+               return 1;
+       return 0;
+}
+
 /*
  * nfsmount_s - Mount an NFSv2 or v3 file system using C string options
  *
@@ -227,6 +251,9 @@ int nfsmount_s(const char *spec, const char *node, int flags,
        if (!append_addr_option(&saddr, options))
                goto out;
 
+       if (!fix_up_mounthost_opt(options))
+               goto out;
+
        if (po_join(options, extra_opts) == PO_FAILED) {
                nfs_error(_("%s: internal option parsing error"), progname);
                goto out;