Re: [patch 13/29] knfsd: reply cache cleanups

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Apr 01, 2009 at 07:28:13AM +1100, Greg Banks wrote:
> Make REQHASH() an inline function.  Rename hash_list to cache_hash.
> Fix an obsolete comment.

OK--applying for 2.6.31.--b.

> 
> Signed-off-by: Greg Banks <gnb@sgi.com>
> ---
> 
>  fs/nfsd/nfscache.c         |   29 +++++++++++++++++++----------
>  include/linux/nfsd/cache.h |    3 +--
>  2 files changed, 20 insertions(+), 12 deletions(-)
> 
> Index: bfields/fs/nfsd/nfscache.c
> ===================================================================
> --- bfields.orig/fs/nfsd/nfscache.c
> +++ bfields/fs/nfsd/nfscache.c
> @@ -29,15 +29,24 @@
>   */
>  #define CACHESIZE		1024
>  #define HASHSIZE		64
> -#define REQHASH(xid)		(((((__force __u32)xid) >> 24) ^ ((__force __u32)xid)) & (HASHSIZE-1))
>  
> -static struct hlist_head *	hash_list;
> +static struct hlist_head *	cache_hash;
>  static struct list_head 	lru_head;
>  static int			cache_disabled = 1;
>  
> +/*
> + * Calculate the hash index from an XID.
> + */
> +static inline u32 request_hash(u32 xid)
> +{
> +	u32 h = xid;
> +	h ^= (xid >> 24);
> +	return h & (HASHSIZE-1);
> +}
> +
>  static int	nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
>  
> -/* 
> +/*
>   * locking for the reply cache:
>   * A cache entry is "single use" if c_state == RC_INPROG
>   * Otherwise, it when accessing _prev or _next, the lock must be held.
> @@ -62,8 +71,8 @@ int nfsd_reply_cache_init(void)
>  		i--;
>  	}
>  
> -	hash_list = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL);
> -	if (!hash_list)
> +	cache_hash = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL);
> +	if (!cache_hash)
>  		goto out_nomem;
>  
>  	cache_disabled = 0;
> @@ -88,8 +97,8 @@ void nfsd_reply_cache_shutdown(void)
>  
>  	cache_disabled = 1;
>  
> -	kfree (hash_list);
> -	hash_list = NULL;
> +	kfree (cache_hash);
> +	cache_hash = NULL;
>  }
>  
>  /*
> @@ -108,7 +117,7 @@ static void
>  hash_refile(struct svc_cacherep *rp)
>  {
>  	hlist_del_init(&rp->c_hash);
> -	hlist_add_head(&rp->c_hash, hash_list + REQHASH(rp->c_xid));
> +	hlist_add_head(&rp->c_hash, cache_hash + request_hash(rp->c_xid));
>  }
>  
>  /*
> @@ -138,7 +147,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp
>  	spin_lock(&cache_lock);
>  	rtn = RC_DOIT;
>  
> -	rh = &hash_list[REQHASH(xid)];
> +	rh = &cache_hash[request_hash(xid)];
>  	hlist_for_each_entry(rp, hn, rh, c_hash) {
>  		if (rp->c_state != RC_UNUSED &&
>  		    xid == rp->c_xid && proc == rp->c_proc &&
> @@ -264,7 +273,7 @@ nfsd_cache_update(struct svc_rqst *rqstp
>  
>  	len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
>  	len >>= 2;
> -	
> +
>  	/* Don't cache excessive amounts of data and XDR failures */
>  	if (!statp || len > (256 >> 2)) {
>  		rp->c_state = RC_UNUSED;
> Index: bfields/include/linux/nfsd/cache.h
> ===================================================================
> --- bfields.orig/include/linux/nfsd/cache.h
> +++ bfields/include/linux/nfsd/cache.h
> @@ -14,8 +14,7 @@
>  #include <linux/uio.h>
>  
>  /*
> - * Representation of a reply cache entry. The first two members *must*
> - * be hash_next and hash_prev.
> + * Representation of a reply cache entry.
>   */
>  struct svc_cacherep {
>  	struct hlist_node	c_hash;
> 
> --
> Greg