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From: Dave Chinner <david@fromorbit.com>
To: Alex Lyakas <alex@zadarastorage.com>
Cc: Brian Foster <bfoster@redhat.com>, xfs@oss.sgi.com
Subject: Re: use-after-free on log replay failure
Date: Wed, 13 Aug 2014 10:03:12 +1000	[thread overview]
Message-ID: <20140813000312.GC20518@dastard> (raw)
In-Reply-To: <DC407F6E8F8C4EE1AF7117D7D6ABF282@alyakaslap>

On Tue, Aug 12, 2014 at 03:39:02PM +0300, Alex Lyakas wrote:
> Then I set up the following Device Mapper target onto /dev/vde:
> dmsetup create VDE --table "0 41943040 linear-custom /dev/vde 0"
> I am attaching the code (and Makefile) of dm-linear-custom target.
> It is exact copy of dm-linear, except that it has a module
> parameter. With the parameter set to 0, this is an identity mapping
> onto /dev/vde. If the parameter is set to non-0, all WRITE bios are
> failed with ENOSPC. There is a workqueue to fail them in a different
> context (not sure if really needed, but that's what our "real"
> custom
> block device does).

FWIW, now I've looked at the dm module, this could easily be added
to the dm-flakey driver by adding a "queue_write_error" option
to it (i.e. similar to the current drop_writes and corrupt_bio_byte
options).

If we add the code there, then we could add a debug-only XFS sysfs
variable to trigger the log recovery sleep, and then use dm-flakey
to queue and error out writes. That gives us a reproducable xfstest
for this condition. Brian, does that sound like a reasonable plan to
you?

Thanks for describing the method you've been using to reproduce the
bug so clearly, Alex.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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  parent reply	other threads:[~2014-08-13  0:03 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-18 18:37 Questions about XFS discard and xfs_free_extent() code (newbie) Alex Lyakas
2013-12-18 23:06 ` Dave Chinner
2013-12-19  9:24   ` Alex Lyakas
2013-12-19 10:55     ` Dave Chinner
2013-12-19 19:24       ` Alex Lyakas
2013-12-21 17:03         ` Chris Murphy
2013-12-24 18:21       ` Alex Lyakas
2013-12-26 23:00         ` Dave Chinner
2014-01-08 18:13           ` Alex Lyakas
2014-01-13  3:02             ` Dave Chinner
2014-01-13 17:44               ` Alex Lyakas
2014-01-13 20:43                 ` Dave Chinner
2014-01-14 13:48                   ` Alex Lyakas
2014-01-15  1:45                     ` Dave Chinner
2014-01-19  9:38                       ` Alex Lyakas
2014-01-19 23:17                         ` Dave Chinner
2014-07-01 15:06                           ` xfs_growfs_data_private memory leak Alex Lyakas
2014-07-01 21:56                             ` Dave Chinner
2014-07-02 12:27                               ` Alex Lyakas
2014-08-04 18:15                                 ` Eric Sandeen
2014-08-06  8:56                                   ` Alex Lyakas
2014-08-04 11:00                             ` use-after-free on log replay failure Alex Lyakas
2014-08-04 14:12                               ` Brian Foster
2014-08-04 23:07                               ` Dave Chinner
2014-08-06 10:05                                 ` Alex Lyakas
2014-08-06 12:32                                   ` Dave Chinner
2014-08-06 14:43                                     ` Alex Lyakas
2014-08-10 16:26                                     ` Alex Lyakas
2014-08-06 12:52                                 ` Alex Lyakas
2014-08-06 15:20                                   ` Brian Foster
2014-08-06 15:28                                     ` Alex Lyakas
2014-08-10 12:20                                     ` Alex Lyakas
2014-08-11 13:20                                       ` Brian Foster
2014-08-11 21:52                                         ` Dave Chinner
2014-08-12 12:03                                           ` Brian Foster
2014-08-12 12:39                                             ` Alex Lyakas
2014-08-12 19:31                                               ` Brian Foster
2014-08-12 23:56                                               ` Dave Chinner
2014-08-13 12:59                                                 ` Brian Foster
2014-08-13 20:59                                                   ` Dave Chinner
2014-08-13 23:21                                                     ` Brian Foster
2014-08-14  6:14                                                       ` Dave Chinner
2014-08-14 19:05                                                         ` Brian Foster
2014-08-14 22:27                                                           ` Dave Chinner
2014-08-13 17:07                                                 ` Alex Lyakas
2014-08-13  0:03                                               ` Dave Chinner [this message]
2014-08-13 13:11                                                 ` Brian Foster

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