Re: [PATCH 8/9] xfs: use iomap_valid method to detect stale cached iomaps

From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 8/9] xfs: use iomap_valid method to detect stale cached iomaps
Date: Tue, 15 Nov 2022 00:49:49 -0800	[thread overview]
Message-ID: <Y3NSrSxq/nC4u8ws@infradead.org> (raw)
In-Reply-To: <20221115013043.360610-9-david@fromorbit.com>

On Tue, Nov 15, 2022 at 12:30:42PM +1100, Dave Chinner wrote:
> +/*
> + * Check that the iomap passed to us is still valid for the given offset and
> + * length.
> + */
> +static bool
> +xfs_iomap_valid(
> +	struct inode		*inode,
> +	const struct iomap	*iomap)
> +{
> +	struct xfs_inode	*ip = XFS_I(inode);
> +	u64			cookie = 0;
> +
> +	if (iomap->flags & IOMAP_F_XATTR) {
> +		cookie = READ_ONCE(ip->i_af.if_seq);
> +	} else {
> +		if ((iomap->flags & IOMAP_F_SHARED) && ip->i_cowfp)
> +			cookie = (u64)READ_ONCE(ip->i_cowfp->if_seq) << 32;
> +		cookie |= READ_ONCE(ip->i_df.if_seq);
> +	}
> +	return cookie == iomap->validity_cookie;

How can this be called with IOMAP_F_XATTR set?

Also the code seems to duplicate xfs_iomap_inode_sequence, so
we just call that:

	return cookie == xfs_iomap_inode_sequence(XFS_I(inode), iomap->flags);