Hi, On 08 Feb 2011, Zabaluev Mikhail (Nokia-MS/Helsinki) wrote: >> I would use fdatasync(). > > What about ensuring that file metadata are synced as well (e.g. the > file itself cannot be lost on the filesystem)?
Rémi already responded about fdatasync semantics, but I do wonder a bit about directory flushing (or lack of it). Many filesystems implement special-casing for rename() which in practise solves the problem, but current ofono code does not actually call rename but instead 'link(tmp,real);unlink(tmp)'. This is ok for transaction safety, but possibly problematic for data safety. So AFAIU, even if we flush tmp (with the patch I sent today), and hardlink, the directory inode might not be flushed for a long time. And I just noticed that e.g. btrfs (which is the default in e.g. MeeGo) does not special case rename() in case destination is not overwritten (but it does have a special case for the overwriting-rename case -> https://btrfs.wiki.kernel.org/index.php/FAQ). So just using fdatasync+rename won't solve all cases either. Hmm, so fdatasync on the file, rename and fsync on directory should be ok then. _______________________________________________ ofono mailing list ofono@ofono.org http://lists.ofono.org/listinfo/ofono
