On Tue 06-11-07 10:04:47, H. Peter Anvin wrote: > Arjan van de Ven wrote: > >On Tue, 6 Nov 2007 18:19:45 +0100 > >Jan Kara <jack@xxxxxxx> wrote: > > > >>Implement recursive mtime (rtime) feature for ext3. The feature works > >>as follows: In each directory we keep a flag EXT3_RTIME_FL > >>(modifiable by a user) whether rtime should be updated. In case a > >>directory or a file in it is modified and when the flag is set, > >>directory's rtime is updated, the flag is cleared, and we move to the > >>parent. If the flag is set there, we clear it, update rtime and > >>continue upwards upto the root of the filesystem. In case a regular > >>file or symlink is modified, we pick arbitrary of its parents > >>(actually the one that happens to be at the head of i_dentry list) > >>and start the rtime update algorith there. > > > >Ok since mtime (and rtime) are part of the inode and not the dentry... > >how do you deal with hardlinks? And with cases of files that have been > >unlinked? (ok the later is a wash obviously other than not crashing) Unlinked files are easy - you just don't propagate the rtime anywhere. For hardlinks see below. > There is only one possible answer... he only updates the directory path > that was used to touch the particular file involved. Thus, the > semantics gets grotty not just in the presence of hard links, but also > in the presence of bind- and other non-root mounts. Update of recursive mtime does not pass filesystem boundaries (i.e. mountpoints) so bind mounts and such are non-issue (hmm, at least that was my original idea but as I'm looking now I don't handle bind mounts properly so that needs to be fixed). With hardlinks, you are right that the behaviour is undeterministic - I tried to argue in the text of the mail that this does not actually matter - there are not many hardlinks on usual system and so the application can check hardlinked files in the old way - i.e. look at mtime. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
