On Fri, Aug 21, 2009 at 03:45:18PM -0700, Joel Becker wrote: > On Fri, Aug 21, 2009 at 06:08:52PM -0400, Theodore Tso wrote: > > http://ext4.wiki.kernel.org/index.php/Clarifying_Direct_IO's_Semantics > > > > Comments are welcome, either on the wiki's talk page, or directly to > > me, or to the linux-fsdevel or linux-ext4. > > In the section on perhaps not waiting for buffered fallback, we > need to clarify that O_DIRECT reads need to know to look in the > pagecache. That is, if we decide that extending O_DIRECT writes without > fsync can return before the data hits the storage, the caller shouldn't > also have to call fsync() just to call read() of data they just wrote! Yeah, I guess we can only do that if the filesystem guarantees coherence between the page cache and O_DIRECT reads; it's been a long while since I've studied that code, so I'm not sure whether all filesystems that support O_DIRECT provide this coherency (since I thought it was provided in the generic O_DIRECT routines, isn't it?) or not. - Ted -- 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
