From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>
Subject: Re: don't use ->bd_inode to access the block device size v3
Date: Mon, 18 Oct 2021 11:16:08 -0600
Message-ID: <4a8c3a39-9cd3-5b2f-6d0f-a16e689755e6@kernel.dk>
References: <20211018101130.1838532-1-hch@lst.de>
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To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Cc: Coly Li <colyli-l3A5Bk7waGM@public.gmane.org>, Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Song Liu <song-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, David Sterba <dsterba-IBi9RG/b67k@public.gmane.org>, Josef Bacik <josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org>, Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>, OGAWA Hirofumi <hirofumi-UIVanBePwB70ZhReMnHkpc8NsWr+9BEh@public.gmane.org>, Dave Kleikamp <shaggy-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Ryusuke Konishi <konishi.ryusuke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Anton Altaparmakov <anton-yrGDUoBaLx3QT0dZR+AlfA@public.gmane.org>, Konstantin Komarov <almaz.alexandrovich-m5I1DM4ARimttCpgsWEBFlaTQe2KTcn/@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Phillip Lougher <phillip-Y7wUz+saRi+tmTQ+vhA3Yw@public.gmane.org>, Jan Kara <jack-IBi9RG/b67k@public.gmane.org>, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, drbd-dev-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org, linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

On 10/18/21 4:11 AM, Christoph Hellwig wrote:
> Hi Jens,
> 
> various drivers currently poke directy at the block device inode, which
> is a bit of a mess.  This series cleans up the places that read the
> block device size to use the proper helpers.  I have separate patches
> for many of the other bd_inode uses, but this series is already big
> enough as-is,

This looks good to me. Followup question, as it's related - I've got a
hacky patch that caches the inode size in the bdev:

https://git.kernel.dk/cgit/linux-block/commit/?h=perf-wip&id=c754951eb7193258c35a574bd1ccccb7c4946ee4

so we don't have to dip into the inode itself for the fast path. While
it's obviously not something being proposed for inclusion right now, is
there a world in which we can make something like that work?

-- 
Jens Axboe