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From: Dave Chinner <david@fromorbit.com>
To: David Howells <dhowells@redhat.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
	linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com,
	viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] VFS: Kill use of O_LARGEFILE inside the kernel
Date: Wed, 23 Sep 2015 07:45:07 +1000	[thread overview]
Message-ID: <20150922214507.GK19114@dastard> (raw)
In-Reply-To: <1458.1442938362@warthog.procyon.org.uk>

On Tue, Sep 22, 2015 at 05:12:42PM +0100, David Howells wrote:
> Theodore Ts'o <tytso@mit.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@fromorbit.com

WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <david@fromorbit.com>
To: David Howells <dhowells@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Theodore Ts'o <tytso@mit.edu>,
	viro@zeniv.linux.org.uk, xfs@oss.sgi.com
Subject: Re: [RFC PATCH 1/2] VFS: Kill use of O_LARGEFILE inside the kernel
Date: Wed, 23 Sep 2015 07:45:07 +1000	[thread overview]
Message-ID: <20150922214507.GK19114@dastard> (raw)
In-Reply-To: <1458.1442938362@warthog.procyon.org.uk>

On Tue, Sep 22, 2015 at 05:12:42PM +0100, David Howells wrote:
> Theodore Ts'o <tytso@mit.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@fromorbit.com

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  parent reply	other threads:[~2015-09-22 21:45 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-22 15:24 [RFC PATCH 1/2] VFS: Kill use of O_LARGEFILE inside the kernel David Howells
2015-09-22 15:24 ` David Howells
2015-09-22 15:25 ` [RFC PATCH 2/2] VFS: Don't pass O_LARGEFILE when opening a file internally David Howells
2015-09-22 15:25   ` David Howells
2015-09-22 15:51 ` [RFC PATCH 1/2] VFS: Kill use of O_LARGEFILE inside the kernel Theodore Ts'o
2015-09-22 15:51   ` Theodore Ts'o
2015-09-22 16:12 ` David Howells
2015-09-22 16:12   ` David Howells
2015-09-22 19:25   ` Theodore Ts'o
2015-09-22 19:25     ` Theodore Ts'o
2015-09-22 21:45   ` Dave Chinner [this message]
2015-09-22 21:45     ` Dave Chinner

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