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From: "Theodore Ts'o" <tytso@mit.edu>
To: Nix <nix@esperi.org.uk>
Cc: Eric Sandeen <sandeen@redhat.com>,
	linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Bryan Schumaker <bjschuma@netapp.com>,
	Peng Tao <bergwolf@gmail.com>,
	Trond.Myklebust@netapp.com, gregkh@linuxfoundation.org,
	linux-nfs@vger.kernel.org
Subject: Re: Apparent serious progressive ext4 data corruption bug in 3.6.3 (and other stable branches?)
Date: Fri, 26 Oct 2012 16:56:18 -0400	[thread overview]
Message-ID: <20121026205618.GC8614@thunk.org> (raw)
In-Reply-To: <87wqydx957.fsf@spindle.srvr.nix>

On Fri, Oct 26, 2012 at 09:37:08PM +0100, Nix wrote:
> 
> I can reproduce this on a small filesystem and stick the image somewhere
> if that would be of any use to anyone. (If I'm very lucky, merely making
> this offer will make the problem go away. :} )

I'm not sure the image is going to be that useful.  What we really
need to do is to get a reliable reproduction of what _you_ are seeing.

It's clear from Eric's experiments that journal_checksum is dangerous.
In fact, I will likely put it under an #ifdef EXT4_EXPERIMENTAL to try
to discourage people from using it in the future.  There are things
I've been planning on doing to make it be safer, but there's a very
good *reason* that both journal_checksum and journal_async_commit are
not on by default.

That's why one of the things I asked you to do when you had time was
to see if you could reproduce the problem you are seeing w/o
nobarrier,journal_checksum,journal_async_commit.

The other experiment that would be really useful if you could do is to
try to apply these two patches which I sent earlier this week:

[PATCH 1/2] ext4: revert "jbd2: don't write superblock when if its empty
[PATCH 2/2] ext4: fix I/O error when unmounting an ro file system

... and see if they make a difference.

If they don't make a difference, I don't want to apply patches just
for placebo/PR reasons.  And for Eric at least, he can reproduce the
journal checksum error followed by fairly significant corruption
reported by e2fsck with journal_checksum, and the presence or absense
of these patches make no difference for him.  So I really don't want
to push these patches to Linus until I get confirmation that they make
a difference to *somebody*.

Regards,

						- Ted

  reply	other threads:[~2012-10-26 20:56 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-22 16:17 Heads-up: 3.6.2 / 3.6.3 NFS server panic: 3.6.2+ regression? Nix
2012-10-23  1:33 ` J. Bruce Fields
2012-10-23 14:07   ` Nix
2012-10-23 14:30     ` J. Bruce Fields
2012-10-23 16:32       ` Heads-up: 3.6.2 / 3.6.3 NFS server oops: 3.6.2+ regression? (also an unrelated ext4 data loss bug) Nix
2012-10-23 16:46         ` J. Bruce Fields
2012-10-23 16:54           ` J. Bruce Fields
2012-10-23 16:56           ` Myklebust, Trond
2012-10-23 17:05             ` Nix
2012-10-23 17:36               ` Nix
2012-10-23 17:43                 ` J. Bruce Fields
2012-10-23 17:44                 ` Myklebust, Trond
2012-10-23 17:57                   ` Myklebust, Trond
     [not found]                   ` <1351015039.4622.23.camel@lade.trondhjem.org>
2012-10-23 18:23                     ` Myklebust, Trond
2012-10-23 19:49                       ` Nix
2012-10-24 10:18                         ` [PATCH] lockd: fix races in per-net NSM client handling Stanislav Kinsbursky
2012-10-23 20:57         ` Apparent serious progressive ext4 data corruption bug in 3.6.3 (and other stable branches?) Nix
2012-10-23 22:19           ` Theodore Ts'o
2012-10-23 22:47             ` Nix
2012-10-23 23:16               ` Theodore Ts'o
2012-10-23 23:06             ` Nix
2012-10-23 23:28               ` Theodore Ts'o
2012-10-23 23:34                 ` Nix
2012-10-24  0:57             ` Eric Sandeen
2012-10-24 20:17               ` Jan Kara
2012-10-26 15:25                 ` Eric Sandeen
2012-10-24 19:13             ` Jannis Achstetter
2012-10-24 21:31               ` Theodore Ts'o
2012-10-24 22:05                 ` Jannis Achstetter
2012-10-24 23:47                 ` Nix
2012-10-25 17:02                 ` Felipe Contreras
2012-10-24 21:04             ` Jannis Achstetter
2012-10-24  1:13           ` Eric Sandeen
2012-10-24  4:15             ` Nix
2012-10-24  4:27               ` Eric Sandeen
2012-10-24  5:23                 ` Theodore Ts'o
2012-10-24  7:00                   ` Hugh Dickins
2012-10-24 11:46                     ` Nix
2012-10-24 11:45                   ` Nix
2012-10-24 17:22                   ` Eric Sandeen
2012-10-24 19:49                   ` Nix
2012-10-24 19:54                     ` Nix
2012-10-24 20:30                     ` Eric Sandeen
2012-10-24 20:34                       ` Nix
2012-10-24 20:45                     ` Nix
2012-10-24 21:08                     ` Theodore Ts'o
2012-10-24 23:27                       ` Apparent serious progressive ext4 data corruption bug in 3.6 (when rebooting during umount) Nix
2012-10-24 23:42                         ` Nix
2012-10-25  1:10                         ` Theodore Ts'o
2012-10-25  1:45                           ` Nix
2012-10-25 14:12                             ` Theodore Ts'o
2012-10-25 14:15                               ` Nix
2012-10-25 17:39                                 ` Nix
2012-10-25 11:06                           ` Nix
2012-10-26  0:22                           ` Apparent serious progressive ext4 data corruption bug in 3.6 (when rebooting during umount) (possibly blockdev / arcmsr at fault??) Nix
2012-10-26  0:11               ` Apparent serious progressive ext4 data corruption bug in 3.6.3 (and other stable branches?) Ric Wheeler
2012-10-26  0:43                 ` Theodore Ts'o
2012-10-26 12:12                   ` Nix
2012-10-26 20:35           ` Eric Sandeen
2012-10-26 20:37             ` Nix
2012-10-26 20:56               ` Theodore Ts'o [this message]
2012-10-26 20:59                 ` Nix
2012-10-26 21:15                   ` Theodore Ts'o
2012-10-26 21:19                     ` Nix
2012-10-27  0:22                       ` Theodore Ts'o
2012-10-27 12:45                         ` Nix
2012-10-27 17:55                           ` Theodore Ts'o
2012-10-27 18:47                             ` Nix
2012-10-27 21:19                               ` Eric Sandeen
2012-10-27 22:42                                 ` Eric Sandeen
2012-10-29  1:00                                   ` Theodore Ts'o
2012-10-29  1:04                                     ` Nix
2012-10-29  2:24                                     ` Eric Sandeen
2012-10-29  2:34                                       ` Theodore Ts'o
2012-10-29  2:35                                         ` Eric Sandeen
2012-10-29  2:42                                           ` Theodore Ts'o
2012-10-27 18:30                           ` Eric Sandeen
2012-10-27  3:11                     ` Jim Rees
2012-10-28  4:23           ` [PATCH] ext4: fix unjournaled inode bitmap modification Eric Sandeen
2012-10-28 13:59             ` Nix
2012-10-29  2:30             ` [PATCH -v3] " Theodore Ts'o
2012-10-29  3:24               ` Eric Sandeen
2012-10-29 17:08               ` Darrick J. Wong
     [not found] <jXsTo-5lW-13@gated-at.bofh.it>
     [not found] ` <jXBDk-7vn-13@gated-at.bofh.it>
     [not found]   ` <jXNl8-5m5-13@gated-at.bofh.it>
     [not found]     ` <jXNOa-5MR-23@gated-at.bofh.it>
     [not found]       ` <jXPGh-87s-5@gated-at.bofh.it>
     [not found]         ` <jXTJW-4CH-55@gated-at.bofh.it>
     [not found]           ` <jXUZj-6mo-13@gated-at.bofh.it>
     [not found]             ` <jXVLH-7kO-5@gated-at.bofh.it>
     [not found]               ` <jXW53-7CC-5@gated-at.bofh.it>
     [not found]                 ` <jXWeJ-7Lk-1@gated-at.bofh.it>
2012-10-24 17:38                   ` Apparent serious progressive ext4 data corruption bug in 3.6.3 (and other stable branches?) Martin
2012-10-26 20:13                     ` Martin
2012-10-26 20:24                       ` Nix
2012-10-26 20:44                         ` Martin
2012-10-26 20:47                           ` Nix
2012-10-26 21:10                       ` Theodore Ts'o
2012-10-26 23:15                         ` Martin

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