On Wed, Apr 05, 2017 at 10:35:26AM +0800, Eryu Guan wrote: > > Test fails with ext3/2 when driving with ext4 driver, fiemap changed > after umount/mount cycle, then changed back to original result after > sleeping some time. An ext4 bug? (cc'ed linux-ext4 list.) I haven't had time to look at this, but I'm not sure this test is a reasonable one on the face of it. A file system may choose to optimize a file's extent tree for whatever reason it wants, whenever it wants, including on an unmount --- and that would not be an invalid thing to do. So to have an xfstests that causes a test failure if a file system were to, say, do some cleanup at mount or unmount time, or when the file is next opened, to merge adjacent extents together (and hence change what is returned by FIEMAP) might be strange, or even weird --- but is this any of user space's business? Or anything we want to enforce as wrong wrong wrong by xfstests? - Ted
