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From: Kent Overstreet <kent.overstreet@gmail.com>
To: Josef Bacik <jbacik@fb.com>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"david@fromorbit.com" <david@fromorbit.com>,
	"hch@lst.de" <hch@lst.de>
Subject: Re: Simulating disk failure with a writeback cache
Date: Mon, 19 Dec 2016 11:55:14 -0900	[thread overview]
Message-ID: <20161219205514.dntaogt3vjos37w2@kmo-pixel> (raw)
In-Reply-To: <1482161254.17731.2@smtp.office365.com>

On Mon, Dec 19, 2016 at 10:27:34AM -0500, Josef Bacik wrote:
> Oh sorry for some reason I only saw this reply but not your previous one
> about seeing the last version of the file.  Yeah that's kind of annoying,
> I'll make a note to fix the test to do a wipefs before doing the log replay.
> Does using wipefs work as well as dd'ing the first bit of the disk for you?
> Thanks,

That worked for the short test, but it won't work in general - the issue is that
in bcache/bcachefs, btree nodes are also log structured, so if we just blow away
the journal we'll still find btree node entries from the future (and it'll
complain loudly on finding btree node entries far in the future of the most
recent journal entry).

For the bug I'm hunting now I'm gonna see if I can reproduce it with a small
enough filesystem that I can just dd over the entire device between replays.

  reply	other threads:[~2016-12-19 20:55 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-15  2:26 Simulating disk failure with a writeback cache Kent Overstreet
2016-12-15  4:15 ` Josef Bacik
2016-12-18 20:12   ` Kent Overstreet
2016-12-18 20:38     ` Josef Bacik
2016-12-18 20:46       ` Kent Overstreet
2016-12-18 21:19         ` Josef Bacik
2016-12-19  2:51           ` Kent Overstreet
2016-12-19  3:07             ` Kent Overstreet
2016-12-19 12:58               ` Josef Bacik
2016-12-19 15:27               ` Josef Bacik
2016-12-19 20:55                 ` Kent Overstreet [this message]
2016-12-19 21:00                   ` Josef Bacik
2016-12-19 21:53                     ` Kent Overstreet
2016-12-20  1:01                       ` Josef Bacik
2016-12-20  1:30                         ` Kent Overstreet

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