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From: Adam Borowski <kilobyte@angband.pl>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH URGENT v1.1 0/2] btrfs-progs: Fix the nobarrier behavior of write
Date: Wed, 27 Mar 2019 15:07:48 +0100	[thread overview]
Message-ID: <20190327140748.GA30466@angband.pl> (raw)
In-Reply-To: <20190327094652.16078-1-wqu@suse.com>

On Wed, Mar 27, 2019 at 05:46:50PM +0800, Qu Wenruo wrote:
> This urgent patchset can be fetched from github:
> https://github.com/adam900710/btrfs-progs/tree/flush_super
> Which is based on v4.20.2.
> 
> Before this patch, btrfs-progs writes to the fs has no barrier at all.
> All metadata and superblock are just buffered write, no barrier between
> super blocks and metadata writes at all.
> 
> No wonder why even clear space cache can cause serious transid
> corruption to the originally good fs.
> 
> Please merge this fix as soon as possible as I really don't want to see
> btrfs-progs corrupting any fs any more.

How often does this happen in practice?  I'm slightly incredulous about
btrfs-progs crashing often.   Especially that pwrite() is buffered on the
kernel side, so we'd need a _kernel_ crash (usually a power loss) to break
consistency.  Obviously, a potential data loss bug is always something that
needs fixing, I'm just wondering about severity.

Or do I understand this wrong?

Asking because Dimitri John Ledkov stepped down as Debian's maintainer of
this package, and I'm taking up the mantle (with Nicholas D Steeves being
around) -- modulo any updates other than important bug fixes being on hold
because of Debian's freeze.  Thus, I wonder if this is important enough to
ask for a freeze exception.


Meow!
-- 
⢀⣴⠾⠻⢶⣦⠀
⣾⠁⢠⠒⠀⣿⡁ Did ya know that typing "test -j8" instead of "ctest -j8"
⢿⡄⠘⠷⠚⠋⠀ will make your testsuite pass much faster, and fix bugs?
⠈⠳⣄⠀⠀⠀⠀

  parent reply	other threads:[~2019-03-27 14:07 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-27  9:46 [PATCH URGENT v1.1 0/2] btrfs-progs: Fix the nobarrier behavior of write Qu Wenruo
2019-03-27  9:46 ` [PATCH URGENT v1.1 1/2] btrfs-progs: disk-io: Make super block write error easier to read Qu Wenruo
2019-03-27 11:34   ` Nikolay Borisov
2019-03-27  9:46 ` [PATCH URGENT v1.1 2/2] btrfs-progs: disk-io: Flush to ensure super block write is FUA Qu Wenruo
2019-03-27 14:07 ` Adam Borowski [this message]
2019-03-27 14:17   ` [PATCH URGENT v1.1 0/2] btrfs-progs: Fix the nobarrier behavior of write Hugo Mills
2019-03-27 14:39   ` Qu Wenruo
2019-03-27 14:42     ` Qu Wenruo
2019-03-27 14:48   ` Qu Wenruo
2019-03-31 14:42     ` Qu Wenruo

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