On Tue, May 04, 2010 at 11:27:50AM -0400, Josef Bacik wrote: > On Tue, May 04, 2010 at 10:14:18AM +1000, Dave Chinner wrote: > > On Mon, May 03, 2010 at 01:27:02PM -0400, Josef Bacik wrote: > > > This is similar to what already happens in the write case. If we have a short > > > read while doing O_DIRECT, instead of just returning, fallthrough and try to > > > read the rest via buffered IO. BTRFS needs this because if we encounter a > > > compressed or inline extent during DIO, we need to fallback on buffered. If the > > > extent is compressed we need to read the entire thing into memory and > > > de-compress it into the users pages. I have tested this with fsx and everything > > > works great. Thanks, > > > > Won't this mean that any direct IO read that spans EOF (i.e. get a > > short read) now attempt a buffered IO (that will fail) before returning? > > > > Hmm yeah you are right. What would be an acceptable way to avoid this, do a > > if (retval || !count || ppos >= i_size_read(inode)) > goto out; > > type thing? Thanks, Yes, that looks like it would work to me. Might be worth a comment, though. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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
