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Date: Wed, 21 Aug 2024 15:14:28 +0200
From: Christoph Hellwig <hch@lst.de>
To: Brian Foster <bfoster@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Christian Brauner <brauner@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Chandan Babu R <chandan.babu@oracle.com>,
	Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Theodore Ts'o <tytso@mit.edu>, linux-block@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-ext4@vger.kernel.org
Subject: Re: [PATCH 3/6] fs: sort out the fallocate mode vs flag mess
Message-ID: <20240821131428.GA22423@lst.de>
References: <20240821063108.650126-1-hch@lst.de> <20240821063108.650126-4-hch@lst.de> <ZsXg4mUWsTya0dNu@bfoster>
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In-Reply-To: <ZsXg4mUWsTya0dNu@bfoster>
User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Aug 21, 2024 at 08:43:14AM -0400, Brian Foster wrote:
> > -	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
> > +	if (mode != FALLOC_FL_ALLOCATE_RANGE && IS_APPEND(inode))
> >  		return -EPERM;
> 
> Unless I'm misreading, this changes semantics by enforcing that we
> cannot use KEEP_SIZE on append only files. That means one can no longer
> do a post-eof prealloc without actually changing the file size, which on
> a quick test seems to work today.

No, I think it was me misreading the old code.  And I'm a little worried
that no test cought it.