On Thu, Feb 14, 2008 at 08:19:19AM +1100, NeilBrown wrote: > On Thu, February 14, 2008 7:26 am, J. Bruce Fields wrote: > > > It's not OK to update it only sometimes. If updates are made while nfsd > > isn't running, those needed to be reflected in the change attribute, so > > the changes aren't missed when nfsd comes back up. > > For NFSD's needs, it is only necessary that changes in i_version that are > potentially visible over NFS actually be stored on disk. > > You could come up with an interface where NFSD sets a flag when it reads > i_version, and changes to the file only change i_version if the flag is > set (at which point the flag is cleared). > > This would give fully correct NFS semantics, and no overhead when NFS access > is not in use > > This flag would need to be stored in stable storage too, so probably easiest > to make it the least significant bit of i_version. > > Of course then the semantics of the new i_version are very different to > the old i_version, so maybe we need two fields in the inode.... Sure. I'd rather have a per-superblock "use i_version" bit than a per-inode "use i_version" bit, just for simplicity's sake, unless there's a really convincing case that it helps. --b. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
