Re: [PATCH 3/3] xfs: track AGs with reclaimable inodes in per-ag radix tree

[Christoph Hellwig <hch@infradead.org>]

> + */
> +static struct xfs_perag *
> +xfs_inode_ag_iter_next_pag(
> +	struct xfs_mount	*mp,
> +	xfs_agnumber_t		*first,
> +	int			tag)
> +{
> +	struct xfs_perag	*pag = NULL;
> +
> +	if (tag == XFS_ICI_RECLAIM_TAG) {
> +		int found;
> +		int ref;
> +
> +		spin_lock(&mp->m_perag_lock);
> +		found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> +				(void **)&pag, *first, 1, tag);
> +		if (found <= 0) {
> +			spin_unlock(&mp->m_perag_lock);
> +			return NULL;
> +		}
> +		*first = pag->pag_agno + 1;
> +		/* open coded pag reference increment */
> +		ref = atomic_inc_return(&pag->pag_ref);
> +		spin_unlock(&mp->m_perag_lock);
> +		trace_xfs_perag_get_reclaim(mp, pag->pag_agno, ref, _RET_IP_);
> +	} else {
> +		pag = xfs_perag_get(mp, *first);
> +		(*first)++;
> +	}

I wonder if we should just split the AG iterator for inode reclaim vs
the rest.  We now have this difference in addition to taking the per-AG
lock exclusive instead of shared.

Anyway, the patch looks good for now,


Reviewed-by: Christoph Hellwig <hch@lst.de>

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