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Date: Mon, 8 Aug 2016 12:08:18 -0400
From: Theodore Ts'o <tytso@....edu>
To: "Darrick J. Wong" <darrick.wong@...cle.com>
Cc: Johannes Stezenbach <js@...21.net>,
Török Edwin <edwin@...rok.net>,
linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: 4.7.0-rc7 ext4 error in dx_probe
On Sun, Aug 07, 2016 at 11:28:10PM -0700, Darrick J. Wong wrote:
>
> I have one lingering concern -- is it a bug that two processes could be
> computing the checksum of a buffer simultaneously? I would have thought ext4
> would serialize that kind of buffer_head access...
Do we know how this is happening? We've always depended on the VFS to
provide this exclusion. The only way we should be modifying the
buffer_head at the same time if two CPU's are trying to modify the
directory at the same time, and that should _never_ be happening, even
with the new directory parallism code, unless the file system has
given permission and intends to do its own fine-grained locking.
- Ted
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