From: Christoph Hellwig <hch@infradead.org>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: Mikulas Patocka <mpatocka@redhat.com>,
Dave Chinner <david@fromorbit.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org, David Teigland <teigland@redhat.com>
Subject: Re: dm-writecache issue
Date: Tue, 18 Sep 2018 08:29:35 -0700 [thread overview]
Message-ID: <20180918152935.GA13016@infradead.org> (raw)
In-Reply-To: <128a77fc-dbcb-278f-115c-da4a3d63e58f@sandeen.net>
On Tue, Sep 18, 2018 at 10:27:20AM -0500, Eric Sandeen wrote:
> (this may be a bit uninformed on my part, Darrick reminds me that jbd2's
> careful use of cache flushing & FUA probably means that it won't get burned
> by a partial 4k metadata update if the power fails.)
cache flushing and FUA is never going to help you with torn writes.
>
> I'll stop for now and see if Dave wants to chime in on xfs's reliance on
> the actual atomic IO size for metadata IO. ;)
What helps todays XFS (and probably ext4) is checksums on all metadata
blocks, as that way we can check if we wrote the full "block". This
doesn't help applications that rely on the sector size unless they have
similar protections of their own.
next prev parent reply other threads:[~2018-09-18 21:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180911221147.GA23308@redhat.com>
2018-09-18 11:46 ` dm-writecache issue Mikulas Patocka
2018-09-18 12:32 ` Dave Chinner
2018-09-18 12:48 ` Eric Sandeen
2018-09-18 14:09 ` Mikulas Patocka
2018-09-18 14:16 ` Eric Sandeen
2018-09-18 14:19 ` Eric Sandeen
2018-09-18 14:29 ` Mikulas Patocka
2018-09-18 14:36 ` Eric Sandeen
2018-09-18 14:42 ` Mikulas Patocka
2018-09-18 15:04 ` Eric Sandeen
2018-09-18 15:27 ` Eric Sandeen
2018-09-18 15:29 ` Christoph Hellwig [this message]
2018-09-18 17:15 ` Mikulas Patocka
2018-09-18 14:20 ` David Teigland
2018-09-18 14:23 ` Eric Sandeen
2018-09-18 14:22 ` Mikulas Patocka
2018-09-18 15:33 ` Christoph Hellwig
2018-09-18 17:39 ` Mikulas Patocka
2018-09-18 22:52 ` Dave Chinner
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