linux-kernel - Re: [PATCH v3 0/3+1] fanotify accounting for fs/splice.c

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Message-ID: <ZJu8OUwWgz1zDVf5@infradead.org>
Date:   Tue, 27 Jun 2023 21:51:05 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Ahelenia Ziemiańska 
        <nabijaczleweli@...ijaczleweli.xyz>
Cc:     Amir Goldstein <amir73il@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jan Kara <jack@...e.cz>,
        Chung-Chiang Cheng <cccheng@...ology.com>, ltp@...r.kernel.org
Subject: Re: [PATCH v3 0/3+1] fanotify accounting for fs/splice.c

Can you please resend this outside this thread?  I really cant't see
what's new or old here if you have a reply-to in the old thread.

On Tue, Jun 27, 2023 at 06:55:22PM +0200, Ahelenia Ziemiańska wrote:
> In 1/3 I've applied if/else if/else tree like you said,
> and expounded a bit in the message.
> 
> This is less pretty now, however, since it turns out that
> iter_file_splice_write() already marks the out fd as written because it
> writes to it via vfs_iter_write(), and that sent a double notification.

It seems like vfs_iter_write is the wrong level to implement
->splice_write given that the the ->splice_write caller has already
checked f_mode, done the equivalent of rw_verify_area and
should do the fsnotify_modify.  I'd suggest to just open code the
relevant parts of vfs_iocb_iter_write in iter_file_splice_write.