linux-ext4 - Re: [PATCH 4/5] afs: Zero bytes after 'oldsize' if we're expanding the file

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Message-ID: <Y/y5rFX2koj2W6Wa@casper.infradead.org>
Date:   Mon, 27 Feb 2023 14:09:48 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-afs@...ts.infradead.org,
        linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-mm@...ck.org, Hugh Dickins <hughd@...gle.com>,
        linux-kernel@...r.kernel.org, fstests@...r.kernel.org
Subject: Re: [PATCH 4/5] afs: Zero bytes after 'oldsize' if we're expanding
 the file

On Mon, Feb 27, 2023 at 01:49:27PM +0000, David Howells wrote:
> Matthew Wilcox (Oracle) <willy@...radead.org> wrote:
> 
> > POSIX requires that "If the file size is increased, the extended area
> > shall appear as if it were zero-filled".  It is possible to use mmap to
> > write past EOF and that data will become visible instead of zeroes.
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> 
> That seems to work.  Do you want me to pass it on to Linus?  If not:
> 
> Acked-by: David Howells <dhowells@...hat.com>

I'll send a patch series with all of this; it doesn't seem terribly
urgent.  Do you think there's a similar problem for AFS that Brian
noted with the generic patch?