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Date: Wed, 24 Jun 2026 16:07:42 +0200
From: Christoph Hellwig <hch@lst.de>
To: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>,
	Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, Carlos Maiolino <cem@kernel.org>,
	linux-xfs@vger.kernel.org, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org,
	Theodore Ts'o <tytso@mit.edu>, linux-ext4@vger.kernel.org,
	Gao Xiang <xiang@kernel.org>, linux-erofs@lists.ozlabs.org
Subject: Re: [PATCH RFC v2 17/18] fs: look up the superblock via the device
 table in user_get_super()
Message-ID: <20260624140742.GD7692@lst.de>
References: <20260616-work-super-bdev_holder_global-v2-0-7df6b864028e@kernel.org> <20260616-work-super-bdev_holder_global-v2-17-7df6b864028e@kernel.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Tue, Jun 16, 2026 at 04:08:33PM +0200, Christian Brauner wrote:
> user_get_super() still finds the superblock for a device number by
> walking the global super_blocks list under sb_lock. Every superblock is
> registered in the device table under its s_dev since sget_fc() inserts
> it there, including superblocks on anonymous devices, so use the table
> instead.

So what is the benefit of this?  It's not like any of these are heavily
used fast paths.