linux-kernel - Re: [RFC PATCH 1/2] VFS: Kill use of O

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Date:	Wed, 23 Sep 2015 07:45:07 +1000
From:	Dave Chinner <david@...morbit.com>
To:	David Howells <dhowells@...hat.com>
Cc:	Theodore Ts'o <tytso@....edu>, linux-fsdevel@...r.kernel.org,
	xfs@....sgi.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] VFS: Kill use of O_LARGEFILE inside the kernel

On Tue, Sep 22, 2015 at 05:12:42PM +0100, David Howells wrote:
> Theodore Ts'o <tytso@....edu> wrote:
> 
> > So what this means is that on 32-bit systems, if we have a userspace
> > program which isn't using the Largefile-enabled, and it opens a file
> > which is larger than can be addressed with a 32-bit off_t, it can get
> > surprised and possibly cause data loss.
> 
> Good point.  I was initially thinking that 32-bit userspace on a 64-bit system
> would have O_LARGEFILE automatically enabled - but I guess it'll trap through
> the compat entry points which avoid that.
> 
> That said, fanotify and xfs_open_by_handle() will both automatically set
> O_LARGEFILE irrespectively of the 32-bitness of the original caller.

Any binaries that use xfs_open_by_handle() and then don't support
greater than 32bit file offsets are simply broken. No ifs or buts -
if you are using low level XFS specific file access ioctls, you need
to build binaries that support 64 bit offsets.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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