Re: [RFC v4+ hot_track 03/19] vfs: add I/O frequency update function

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On Mon, 2012-10-29 at 12:30 +0800, zwu.kernel@gmail.com wrote:
> From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
> 
>   Add some util helpers to update access frequencies
> for one file or its range.
> 
> Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
> ---
>  fs/hot_tracking.c            |  179 ++++++++++++++++++++++++++++++++++++++++++
>  fs/hot_tracking.h            |    7 ++
>  include/linux/hot_tracking.h |    2 +
>  3 files changed, 188 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
> index 68591f0..0a7d9a3 100644
> --- a/fs/hot_tracking.c
> +++ b/fs/hot_tracking.c
> @@ -172,6 +172,137 @@ static void hot_inode_tree_exit(struct hot_info *root)
>  	}
>  }
>  
> +struct hot_inode_item
> +*hot_inode_item_find(struct hot_info *root, u64 ino)
> +{
> +	struct hot_inode_item *he;
> +	int ret;
> +
> +again:
> +	spin_lock(&root->lock);
> +	he = radix_tree_lookup(&root->hot_inode_tree, ino);
> +	if (he) {
> +		kref_get(&he->hot_inode.refs);
> +		spin_unlock(&root->lock);
> +		return he;
> +	}
> +	spin_unlock(&root->lock);
> +
> +	he = kmem_cache_zalloc(hot_inode_item_cachep,
> +				GFP_KERNEL | GFP_NOFS);
This doesn't look quite right... which of these two did you mean? I
assume probably just GFP_NOFS

> +	if (!he)
> +		return ERR_PTR(-ENOMEM);
> +
> +	hot_inode_item_init(he, ino, &root->hot_inode_tree);
> +
> +	ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
> +	if (ret) {
> +		kmem_cache_free(hot_inode_item_cachep, he);
> +		return ERR_PTR(ret);
> +	}
> +
> +	spin_lock(&root->lock);
> +	ret = radix_tree_insert(&root->hot_inode_tree, ino, he);
> +	if (ret == -EEXIST) {
> +		kmem_cache_free(hot_inode_item_cachep, he);
> +		spin_unlock(&root->lock);
> +		radix_tree_preload_end();
> +		goto again;
> +	}
> +	spin_unlock(&root->lock);
> +	radix_tree_preload_end();
> +
> +	kref_get(&he->hot_inode.refs);
> +	return he;
> +}
> +EXPORT_SYMBOL_GPL(hot_inode_item_find);
> +
> +static struct hot_range_item
> +*hot_range_item_find(struct hot_inode_item *he,
> +			u32 start)
> +{
> +	struct hot_range_item *hr;
> +	int ret;
> +
> +again:
> +	spin_lock(&he->lock);
> +	hr = radix_tree_lookup(&he->hot_range_tree, start);
> +	if (hr) {
> +		kref_get(&hr->hot_range.refs);
> +		spin_unlock(&he->lock);
> +		return hr;
> +	}
> +	spin_unlock(&he->lock);
> +
> +	hr = kmem_cache_zalloc(hot_range_item_cachep,
> +				GFP_KERNEL | GFP_NOFS);
Likewise, here too.

Steve.