linux-kernel - Re: [PATCH 3/6] block: open code __generic_file_write

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Message-ID: <20230829130327.GA26482@lst.de>
Date:   Tue, 29 Aug 2023 15:03:27 +0200
From:   Christoph Hellwig <hch@....de>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Christian Brauner <christian@...uner.io>,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] block: open code __generic_file_write_iter for
 blkdev writes

On Tue, Aug 29, 2023 at 03:06:14AM +0100, Al Viro wrote:
> 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...

I'll send an incremental patch to remove it once the changes hit
Linus' tree.