> > > The criteria for using O_NOMTIME is the same as for using O_NOATIME: > > > owning the file or having the CAP_FOWNER capability. If we're not > > > comfortable allowing owners to prevent mtime/ctime updates then we > > > should add a tunable to allow O_NOMTIME. Maybe a mount option? > > > > I dislike "turn off safety for performance" options because Joe > > SpeedRacer will always select performance over safety. > > Well, for ceph there's no safety concern. They never use cmtime in > these files. > > So are you suggesting not implementing this and making them rework their > IO paths to avoid the fs maintaining mtime so that we don't give Joe > Speedracer more rope? Or are we talking about adding some speed bumps > that ceph can flip on that might give Joe Speedracer pause? Maybe one way to make it less of an attractive nuisance would be to hide it under open_by_handle_at(). Like xfs_open_by_handle() does today but we probably don't want to unconditionally add it to the generic path so we'd have a flag. They want to move to opening by handles anyway to avoid dirent lookups when opening cold files. - z -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
