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From: Theodore Ts'o <tytso@mit.edu>
To: Lukas Czerner <lczerner@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	xfs@oss.sgi.com
Subject: Re: [PATCH 3/3 v2] fs: move falloc collapse range check into the filesystem methods
Date: Tue, 15 Apr 2014 22:55:21 -0400	[thread overview]
Message-ID: <20140416025521.GC21807@thunk.org> (raw)
In-Reply-To: <1397580076-19826-3-git-send-email-lczerner@redhat.com>

On Tue, Apr 15, 2014 at 06:41:16PM +0200, Lukas Czerner wrote:
> Currently in do_fallocate in collapse range case we're checking whether
> offset + len is not bigger than i_size. However there is nothing which
> would prevent i_size from changing so the check is pointless. It should
> be done in the file system itself and the file system needs to make sure
> that i_size is not going to change. The i_size check for the other
> fallocate modes are also done in the filesystems.
> 
> As it is now we can easily crash kernel by having two processes doing
> truncate and fallocate collapse range at the same time. This can be
> reproduced on ext4 and it is theoretically possible on xfs even though I
> was not able to trigger it with this simple test.
> 
> This commit removes the check from do_fallocate and adds it to the file
> system.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> Acked-by: Dave Chinner <david@fromorbit.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Thanks, updated.

						- Ted

WARNING: multiple messages have this Message-ID (diff)
From: Theodore Ts'o <tytso@mit.edu>
To: Lukas Czerner <lczerner@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	xfs@oss.sgi.com
Subject: Re: [PATCH 3/3 v2] fs: move falloc collapse range check into the filesystem methods
Date: Tue, 15 Apr 2014 22:55:21 -0400	[thread overview]
Message-ID: <20140416025521.GC21807@thunk.org> (raw)
In-Reply-To: <1397580076-19826-3-git-send-email-lczerner@redhat.com>

On Tue, Apr 15, 2014 at 06:41:16PM +0200, Lukas Czerner wrote:
> Currently in do_fallocate in collapse range case we're checking whether
> offset + len is not bigger than i_size. However there is nothing which
> would prevent i_size from changing so the check is pointless. It should
> be done in the file system itself and the file system needs to make sure
> that i_size is not going to change. The i_size check for the other
> fallocate modes are also done in the filesystems.
> 
> As it is now we can easily crash kernel by having two processes doing
> truncate and fallocate collapse range at the same time. This can be
> reproduced on ext4 and it is theoretically possible on xfs even though I
> was not able to trigger it with this simple test.
> 
> This commit removes the check from do_fallocate and adds it to the file
> system.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> Acked-by: Dave Chinner <david@fromorbit.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Thanks, updated.

						- Ted

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  reply	other threads:[~2014-04-16  2:55 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-15 16:41 [PATCH 1/3 v2] ext4: Remove unnecessary check for APPEND and IMMUTABLE Lukas Czerner
2014-04-15 16:41 ` [PATCH 2/3 v2] fs: Prevent doing FALLOC_FL_ZERO_RANGE on append only file Lukas Czerner
2014-04-15 22:02   ` Dave Chinner
2014-04-15 22:02     ` Dave Chinner
2014-04-16  2:51     ` Theodore Ts'o
2014-04-16  2:51       ` Theodore Ts'o
2014-04-16  8:29     ` Lukáš Czerner
2014-04-15 16:41 ` [PATCH 3/3 v2] fs: move falloc collapse range check into the filesystem methods Lukas Czerner
2014-04-16  2:55   ` Theodore Ts'o [this message]
2014-04-16  2:55     ` Theodore Ts'o

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