On Fri, Jan 5, 2018 at 5:43 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > On Thu, Jan 04, 2018 at 06:40:01PM +0200, Amir Goldstein wrote: >> Introduce the "verify" config, module and mount options. >> >> If the "verify" feature is enabled then overlay filesystems will use >> the inodes index dir to verify layers consistency. >> >> It is possible to enable consistency verification by default during >> build time with the OVERLAY_FS_VERIFY config option, during runtime >> with the "verify=on" module option or on a filesystem instance basis >> with the "verify=on" mount option. >> >> The "verify" feature will prevent multiple redirects to the same lower >> dir and will prevent broken hardlinks from using the same inode number. > > So how does one end up with multiple redirects to same lower dir. > > Also what's the issue with broken hardlinks using same inode number. You > mean lower and upper are on different fs and upper can use same inode > number? With index=on, broken hardlink issue is taken care of so. So > why would somebody use verify=on, which looks like will create index > for all kind of files/dir. > > I have not followed this development and there is not much background > in patch descrition or header patch, so asking all these basic questions. > I have a ready answer for you :) This is how it can happen and this is what can go wrong: https://github.com/amir73il/xfstests/commit/f3c18125539660329195f142973ea620d6899418 The test duplicates a redirect dir offline with cp -a, but the same thing can be done with a dir with origin. In both cases, 'diff' will wrongly report that the files/dir are the same even though they may differ (after being copied). Amir. -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
