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Date: Tue, 12 Oct 2021 23:29:39 -0700
From: Kees Cook <keescook@chromium.org>
To: Christoph Hellwig <hch@lst.de>
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	<20211013051042.1065752-26-hch@lst.de>
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Cc: Dave Kleikamp <shaggy@kernel.org>, jfs-discussion@lists.sourceforge.net,
	Mike Snitzer <snitzer@redhat.com>, linux-nvme@lists.infradead.org,
	Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
	Song Liu <song@kernel.org>, dm-devel@redhat.com,
	target-devel@vger.kernel.org, linux-mtd@lists.infradead.org,
	reiserfs-devel@vger.kernel.org, drbd-dev@lists.linbit.com,
	linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org,
	OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
	linux-ext4@vger.kernel.org, Josef Bacik <josef@toxicpanda.com>,
	Coly Li <colyli@suse.de>, linux-raid@vger.kernel.org,
	linux-bcache@vger.kernel.org, David Sterba <dsterba@suse.com>,
	Ryusuke Konishi <konishi.ryusuke@gmail.com>,
	Anton Altaparmakov <anton@tuxera.com>,
	Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
	linux-nfs@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
	linux-ntfs-dev@lists.sourceforge.net, Jan Kara <jack@suse.com>,
	linux-fsdevel@vger.kernel.org,
	Phillip Lougher <phillip@squashfs.org.uk>, ntfs3@lists.linux.dev,
	linux-btrfs@vger.kernel.org
Subject: Re: [Drbd-dev] [PATCH 25/29] ext4: use sb_bdev_nr_blocks
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On Wed, Oct 13, 2021 at 07:10:38AM +0200, Christoph Hellwig wrote:
> Use the sb_bdev_nr_blocks helper instead of open coding it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/ext4/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 0775950ee84e3..3dde8be5df490 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4468,7 +4468,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  		goto cantfind_ext4;
>  
>  	/* check blocks count against device size */
> -	blocks_count = sb->s_bdev->bd_inode->i_size >> sb->s_blocksize_bits;
> +	blocks_count = sb_bdev_nr_blocks(sb);

Is s_blocksize_bits always 9 here? If not, this isn't equivalent.

-Kees

>  	if (blocks_count && ext4_blocks_count(es) > blocks_count) {
>  		ext4_msg(sb, KERN_WARNING, "bad geometry: block count %llu "
>  		       "exceeds size of device (%llu blocks)",
> -- 
> 2.30.2
> 

-- 
Kees Cook