Re: [PATCH RFC v2 17/18] fs: look up the superblock via the device table in user_get_super()

Christoph Hellwig <[email protected]> Wed, 24 Jun 2026 16:07:42 +0200
Newsgroups org.ozlabs.lists.linux-erofs,org.kernel.vger.linux-block,org.kernel.vger.linux-btrfs,org.kernel.vger.linux-ext4,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-xfs
Message-ID <[email protected]>
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.