NILFS2: 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: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/nilfs2/namei.c

@@ -496,8 +496,7 @@ static struct dentry *nilfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 {
 	struct nilfs_fid *fid = (struct nilfs_fid *)fh;
 
-	if ((fh_len != NILFS_FID_SIZE_NON_CONNECTABLE &&
-	     fh_len != NILFS_FID_SIZE_CONNECTABLE) ||
+	if (fh_len < NILFS_FID_SIZE_NON_CONNECTABLE ||
 	    (fh_type != FILEID_NILFS_WITH_PARENT &&
 	     fh_type != FILEID_NILFS_WITHOUT_PARENT))
 		return NULL;
@@ -510,7 +509,7 @@ static struct dentry *nilfs_fh_to_parent(struct super_block *sb, struct fid *fh,
 {
 	struct nilfs_fid *fid = (struct nilfs_fid *)fh;
 
-	if (fh_len != NILFS_FID_SIZE_CONNECTABLE ||
+	if (fh_len < NILFS_FID_SIZE_CONNECTABLE ||
 	    fh_type != FILEID_NILFS_WITH_PARENT)
 		return NULL;