staging: erofs: cannot set EROFS_V_Z_INITED_BIT if fill_inode_lazy fails

As reported by erofs-utils fuzzer, unsupported compressed
clustersize will make fill_inode_lazy fail, for such case
we cannot set EROFS_V_Z_INITED_BIT since we need return
failure for each z_erofs_map_blocks_iter().

Fixes: 152a333a ("staging: erofs: add compacted compression indexes support")
Cc: <stable@vger.kernel.org> # 5.3+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190819103426.87579-3-gaoxiang25@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/zmap.c

@@ -85,12 +85,11 @@ static int fill_inode_lazy(struct inode *inode)
 
 	vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits +
 					((h->h_clusterbits >> 5) & 7);
+	set_bit(EROFS_V_Z_INITED_BIT, &vi->flags);
 unmap_done:
 	kunmap_atomic(kaddr);
 	unlock_page(page);
 	put_page(page);
-
-	set_bit(EROFS_V_Z_INITED_BIT, &vi->flags);
 out_unlock:
 	clear_and_wake_up_bit(EROFS_V_BL_Z_BIT, &vi->flags);
 	return err;