From: Christoph Hellwig <hch@lst.de>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Chris Mason <clm@fb.com>, Christoph Hellwig <hch@lst.de>,
Jan Kara <jack@suse.cz>,
josef@toxicpanda.com, dsterba@suse.com,
linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] btrfs: remove btrfs_writepage_cow_fixup
Date: Wed, 29 Jun 2022 10:40:08 +0200 [thread overview]
Message-ID: <20220629084008.GA25536@lst.de> (raw)
In-Reply-To: <b29ee79c-e0d9-7ebe-a563-ca7f33130fc9@gmx.com>
On Wed, Jun 29, 2022 at 09:20:59AM +0800, Qu Wenruo wrote:
> In fact, COW is not that special, even before btrfs or all the other
> fses supporting COW, all those old fses has to do something like COW,
> when they are writing into holes.
>
> What makes btrfs special is its csum, and in fact csum requires more
> stable page status.
>
> If someone can modify a page without waiting for its writeback to
> finish, btrfs csum can easily be stale and cause -EIO for future read.
And the writepage time fixup does not help with this at all, as it
just allocates the ordered extent at writepage time, long after the
data has been modified.
next prev parent reply other threads:[~2022-06-29 8:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 12:23 [PATCH] btrfs: remove btrfs_writepage_cow_fixup Christoph Hellwig
2022-06-24 12:30 ` Qu Wenruo
2022-06-24 12:51 ` Christoph Hellwig
2022-06-24 13:07 ` Jan Kara
2022-06-24 13:19 ` Qu Wenruo
2022-06-24 13:40 ` Jan Kara
2022-06-24 13:56 ` Qu Wenruo
2022-06-27 10:15 ` Jan Kara
2022-06-25 9:11 ` Christoph Hellwig
2022-06-27 10:19 ` Jan Kara
2022-06-28 0:24 ` Qu Wenruo
2022-06-28 8:00 ` Jan Kara
2022-06-29 1:33 ` Qu Wenruo
2022-06-29 10:03 ` Jan Kara
2022-06-28 11:53 ` David Sterba
2022-06-29 7:58 ` Christoph Hellwig
2022-07-05 14:21 ` Gerald Schaefer
2022-06-28 11:46 ` David Sterba
2022-06-28 14:29 ` Chris Mason
2022-06-29 1:20 ` Qu Wenruo
2022-06-29 8:40 ` Christoph Hellwig [this message]
2022-06-29 8:38 ` Christoph Hellwig
2022-06-29 9:45 ` Jan Kara
2022-06-29 13:59 ` Christoph Hellwig
2022-06-24 12:49 ` David Sterba
2022-06-24 13:12 ` Qu Wenruo
2022-06-24 13:27 ` David Sterba
2022-06-24 13:50 ` Qu Wenruo
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