From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz,
Askar Safin <safinaskar@gmail.com>
Subject: Re: [PATCH RFC 2/2] fs: fully sync all fses even for an emergency sync
Date: Mon, 3 Nov 2025 03:56:22 -0800 [thread overview]
Message-ID: <aQiYZqX5aGn-FW56@infradead.org> (raw)
In-Reply-To: <7b7fd40c5fe440b633b6c0c741d96ce93eb5a89a.1762142636.git.wqu@suse.com>
The emergency sync being non-blocking goes back to day 1. I think the
idea behind it is to not lock up a already messed up system by
blocking forever, even if it is in workqueue. Changing this feels
a bit risky to me.
On Mon, Nov 03, 2025 at 02:37:29PM +1030, Qu Wenruo wrote:
> At this stage, btrfs is only one super block update away to be fully committed.
> I believe it's the more or less the same for other fses too.
Most file systems do not need a superblock update to commit data.
> The problem is the next step, sync_bdevs().
> Normally other fses have their super block already updated in the page
> cache of the block device, but btrfs only updates the super block during
> full transaction commit.
>
> So sync_bdevs() may work for other fses, but not for btrfs, btrfs is
> still using its older super block, all pointing back to the old metadata
> and data.
>
At least for XFS, no metadata is written through the block device
mapping anyway.
next prev parent reply other threads:[~2025-11-03 11:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-03 4:07 [PATCH RFC 0/2] fs: fully sync all fsese even for an emergency sync Qu Wenruo
2025-11-03 4:07 ` [PATCH RFC 1/2] fs: do not pass a parameter for sync_inodes_one_sb() Qu Wenruo
2025-11-03 11:51 ` Christoph Hellwig
2025-11-04 8:42 ` Jan Kara
2025-11-05 18:50 ` Daniel Vacek
2025-11-03 4:07 ` [PATCH RFC 2/2] fs: fully sync all fses even for an emergency sync Qu Wenruo
2025-11-03 11:56 ` Christoph Hellwig [this message]
2025-11-03 12:04 ` Christoph Hellwig
2025-11-03 20:46 ` Qu Wenruo
2025-11-03 20:55 ` Qu Wenruo
2025-11-04 8:28 ` Jan Kara
2025-11-04 8:39 ` Jan Kara
2025-11-05 11:32 ` Christian Brauner
2025-11-04 8:43 ` Qu Wenruo
2025-11-04 12:42 ` Jan Kara
2025-11-04 15:48 ` Christoph Hellwig
2025-11-03 16:00 ` [PATCH RFC 0/2] fs: fully sync all fsese " Askar Safin
2025-11-05 11:31 ` Christian Brauner
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