On Tue, Apr 26, 2016 at 09:49:46AM +1000, Dave Chinner wrote: > Why not just transparently fall back to buffered IO if direct IO > cannot be done? Saves people from wondering why applications fail > on one ext4 filesystem and not another.... I've been doing an audit of our direct I/O implementations, and most of them does some form of transparent fallback, including some that only pretend to support O_DIRECT, but do anything special for it at all, while at the same time we go through greast efforts to check a file system actualy supports direct I/O, leading to nasty no-op ->direct_IO implementations as we even got that abstraction wrong. At this point I wonder if we should simply treat O_DIRECT as a hint and always allow it, and just let the file system optimize for it (skip buffering, require alignment, relaxed Posix atomicy requirements) if it is set. -- 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
