linux-kernel - Re: [PATCH 1/3] fs: allow short direct-io reads to be completed via buffered IO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 4 May 2010 10:14:18 +1000
From:	Dave Chinner <david@...morbit.com>
To:	Josef Bacik <josef@...hat.com>
Cc:	linux-btrfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...r.kernel.org
Subject: Re: [PATCH 1/3] fs: allow short direct-io reads to be completed
 via buffered IO

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@...morbit.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/