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Date:   Tue, 29 Aug 2023 03:06:14 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Jens Axboe <axboe@kernel.dk>,
        "Darrick J. Wong" <djwong@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] block: open code __generic_file_write_iter for
 blkdev writes
Message-ID: <20230829020614.GB325446@ZenIV>
References: <20230801172201.1923299-1-hch@lst.de>
 <20230801172201.1923299-4-hch@lst.de>
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On Tue, Aug 01, 2023 at 07:21:58PM +0200, Christoph Hellwig wrote:
> @@ -569,7 +594,23 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		iov_iter_truncate(from, size);
>  	}
>  
> -	ret = __generic_file_write_iter(iocb, from);
> +	ret = file_remove_privs(file);
> +	if (ret)
> +		return ret;

That chunk is a bit of a WTF generator...  Thankfully,

static int __file_remove_privs(struct file *file, unsigned int flags)
{
        struct dentry *dentry = file_dentry(file);
	struct inode *inode = file_inode(file);
	int error = 0;
	int kill;

	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
		return 0;

means that it's really a no-op.  But I'd still suggest
removing it, just to reduce the amount of head-scratching
for people who'll be reading that code later...