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From: "Theodore Ts'o" <tytso@mit.edu>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: "Johannes Stezenbach" <js@sig21.net>,
	"Török Edwin" <edwin@etorok.net>,
	linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: 4.7.0-rc7 ext4 error in dx_probe
Date: Mon, 8 Aug 2016 12:08:18 -0400	[thread overview]
Message-ID: <20160808160818.GA9515@thunk.org> (raw)
In-Reply-To: <20160808062810.GC8590@birch.djwong.org>

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

  reply	other threads:[~2016-08-08 16:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-18 10:57 4.7.0-rc7 ext4 error in dx_probe Johannes Stezenbach
2016-07-18 13:38 ` Theodore Ts'o
2016-07-18 14:17   ` Johannes Stezenbach
2016-07-27 11:58     ` Johannes Stezenbach
2016-08-03 14:50     ` Török Edwin
2016-08-05 10:35       ` Johannes Stezenbach
2016-08-05 17:02         ` Darrick J. Wong
2016-08-05 18:11           ` Johannes Stezenbach
2016-08-05 19:15             ` Darrick J. Wong
2016-08-08  3:56               ` Theodore Ts'o
2016-08-08  6:28                 ` Darrick J. Wong
2016-08-08 16:08                   ` Theodore Ts'o [this message]
2016-08-08 16:55                     ` Darrick J. Wong
2016-08-08 21:13                       ` Török Edwin
2016-08-09  2:37                         ` Darrick J. Wong
2016-08-09  7:12                           ` Török Edwin
2016-08-17 14:27                   ` Török Edwin
2016-08-17 23:28                     ` Darrick J. Wong
2016-08-22  7:33                       ` Török Edwin
2016-09-01 16:40                         ` Darrick J. Wong
2016-08-17 20:02             ` Johannes Stezenbach
2016-08-18  7:44               ` Török Edwin

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