/*
* Handle NFS version and transport protocol
* autonegotiation.
*
* When no version or protocol is specified on the
* command line, mount.nfs negotiates with the server
* to determine appropriate settings for the new
* mount point.
*
* Returns TRUE if successful, otherwise FALSE.
* "errno" is set to reflect the individual error.
*/
static int nfs_autonegotiate(struct nfsmount_info *mi)
{
int result;
result = nfs_try_mount_v4(mi);
if (result)
return result;
switch (errno) {
case EPROTONOSUPPORT:
/* A clear indication that the server or our
* client does not support NFS version 4. */
goto fall_back;
case ENOENT:
/* Legacy Linux servers don't export an NFS
* version 4 pseudoroot. */
goto fall_back;
case EPERM:
/* Linux servers prior to 2.6.25 may return
* EPERM when NFS version 4 is not supported. */
goto fall_back;
default:
return result;
}
fall_back:
return nfs_try_mount_v3v2(mi);
}
/*
* Handle NFS version and transport protocol
* autonegotiation.
*
* When no version or protocol is specified on the
* command line, mount.nfs negotiates with the server
* to determine appropriate settings for the new
* mount point.
*
* Returns TRUE if successful, otherwise FALSE.
* "errno" is set to reflect the individual error.
*/
static int nfs_autonegotiate(struct nfsmount_info *mi)
{
int result;
result = nfs_try_mount_v4(mi);
if (result)
return result;
check_errno:
switch (errno) {
case EPROTONOSUPPORT:
/* A clear indication that the server or our
* client does not support NFS version 4. */
goto fall_back;
case ENOENT:
/* Legacy Linux servers don't export an NFS
* version 4 pseudoroot. */
goto fall_back;
case EPERM:
/* Linux servers prior to 2.6.25 may return
* EPERM when NFS version 4 is not supported. */
goto fall_back;
case ECONNREFUSED:
/* UDP-Only servers won't support v4, but maybe it
* just isn't ready yet. So try v3, but double-check
* with rpcbind for v4. */
result = nfs_try_mount_v3v2(mi, TRUE);
if (result == 0 && errno == EAGAIN) {
/* v4 server seems to be registered now. */
result = nfs_try_mount_v4(mi);
if (result == 0 && errno != ECONNREFUSED)
goto check_errno;
}
return result;
default:
return result;
}
fall_back:
return nfs_try_mount_v3v2(mi, FALSE);
}
/*
* This is a single pass through the fg/bg loop.
*
* Returns TRUE if successful, otherwise FALSE.
* "errno" is set to reflect the individual error.
*/
static int nfs_try_mount(struct nfsmount_info *mi)
{
int result = 0;
switch (mi->version) {
case 0:
result = nfs_autonegotiate(mi);
break;
case 2:
case 3:
result = nfs_try_mount_v3v2(mi, FALSE);
break;
case 4:
result = nfs_try_mount_v4(mi);
break;
default:
errno = EIO;
}
return result;
}