UDF: support NFSv2 export

The "fh_len" passed to ->fh_to_* is not guaranteed to be that same as
that returned by encode_fh - it may be larger.

With NFSv2, the filehandle is fixed length, so it may appear longer
than expected and be zero-padded.

So we must test that fh_len is at least some value, not exactly equal
to it.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/namei.c

@@ -1272,7 +1272,7 @@ static struct dentry *udf_nfs_get_inode(struct super_block *sb, u32 block,
 static struct dentry *udf_fh_to_dentry(struct super_block *sb,
 				       struct fid *fid, int fh_len, int fh_type)
 {
-	if ((fh_len != 3 && fh_len != 5) ||
+	if (fh_len < 3 ||
 	    (fh_type != FILEID_UDF_WITH_PARENT &&
 	     fh_type != FILEID_UDF_WITHOUT_PARENT))
 		return NULL;
@@ -1284,7 +1284,7 @@ static struct dentry *udf_fh_to_dentry(struct super_block *sb,
 static struct dentry *udf_fh_to_parent(struct super_block *sb,
 				       struct fid *fid, int fh_len, int fh_type)
 {
-	if (fh_len != 5 || fh_type != FILEID_UDF_WITH_PARENT)
+	if (fh_len < 5 || fh_type != FILEID_UDF_WITH_PARENT)
 		return NULL;
 
 	return udf_nfs_get_inode(sb, fid->udf.parent_block,