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Date: Wed, 25 Mar 2026 09:00:21 +0100
From: Christoph Hellwig <hch@lst.de>
To: Andrey Albershteyn <aalbersh@kernel.org>
Cc: linux-xfs@vger.kernel.org, fsverity@lists.linux.dev,
	linux-fsdevel@vger.kernel.org, ebiggers@kernel.org, hch@lst.de,
	linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
	linux-btrfs@vger.kernel.org, djwong@kernel.org
Subject: Re: [PATCH v5 07/25] iomap: introduce IOMAP_F_FSVERITY and teach
 writeback to handle fsverity
Message-ID: <20260325080021.GF952@lst.de>
References: <20260319170231.1455553-1-aalbersh@kernel.org> <20260319170231.1455553-8-aalbersh@kernel.org>
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In-Reply-To: <20260319170231.1455553-8-aalbersh@kernel.org>
User-Agent: Mutt/1.5.17 (2007-11-01)

> @@ -353,9 +353,16 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
>  {
>  	const struct iomap *srcmap = iomap_iter_srcmap(iter);
>  
> -	return srcmap->type != IOMAP_MAPPED ||
> -		(srcmap->flags & IOMAP_F_NEW) ||
> -		pos >= i_size_read(iter->inode);
> +	if (srcmap->type != IOMAP_MAPPED)
> +		return true;
> +
> +	if (srcmap->flags & IOMAP_F_NEW)
> +		return true;
> +
> +	if (srcmap->flags & IOMAP_F_FSVERITY)
> +		return false;
> +
> +	return pos >= i_size_read(iter->inode);

This might be a good time to document the various reasons for needing
zeroing.

> +/*
> + * IO happens beyond inode EOF, fsverity metadata is stored there
> + */
> +#define IOMAP_F_FSVERITY	(1U << 10)

This comment feels a bit too sparse.  Here is my interpretation of what
this flag does:

/*
 * Indicates reads and writes of fsverity metadata.
 *
 * Fsverity metadata is stored after the regular file data and thus beyond
 * i_size.
 */