Re: [PATCH 1/3] fs: allow short direct-io reads to be completedvia buffered IO

[Dave Chinner]

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?

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx
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