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Date:   Tue, 15 Nov 2022 15:26:27 -0800
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Dave Chinner <david@fromorbit.com>, 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
Message-ID: <Y3QgI9CM1oEKMEE/@magnolia>
References: <20221115013043.360610-1-david@fromorbit.com>
 <20221115013043.360610-9-david@fromorbit.com>
 <Y3NSrSxq/nC4u8ws@infradead.org>
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On Tue, Nov 15, 2022 at 12:49:49AM -0800, Christoph Hellwig wrote:
> 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?

xfs_xattr_iomap_begin for FIEMAP, if I'm not mistaken.

> 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);

I was thinking that too.

--D