[mirror_ubuntu-artful-kernel.git] / fs / nfsd / nfscache.c

/*
 * Request reply cache. This is currently a global cache, but this may
 * change in the future and be a per-client cache.
 *
 * This code is heavily inspired by the 44BSD implementation, although
 * it does things a bit differently.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/slab.h>
#include <linux/sunrpc/clnt.h>

#include "nfsd.h"
#include "cache.h"

/* Size of reply cache. Common values are:
 * 4.3BSD:	128
 * 4.4BSD:	256
 * Solaris2:	1024
 * DEC Unix:	512-4096
 */
#define CACHESIZE		1024
#define HASHSIZE		64

static struct hlist_head *	cache_hash;
static struct list_head 	lru_head;
static int			cache_disabled = 1;
static struct kmem_cache	*drc_slab;
static unsigned int		num_drc_entries;

/*
 * 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.
 */
static DEFINE_SPINLOCK(cache_lock);

static struct svc_cacherep *
nfsd_reply_cache_alloc(void)
{
	struct svc_cacherep	*rp;

	rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
	if (rp) {
		rp->c_state = RC_UNUSED;
		rp->c_type = RC_NOCACHE;
		INIT_LIST_HEAD(&rp->c_lru);
		INIT_HLIST_NODE(&rp->c_hash);
	}
	return rp;
}

static void
nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
{
	if (rp->c_type == RC_REPLBUFF)
		kfree(rp->c_replvec.iov_base);
	list_del(&rp->c_lru);
	--num_drc_entries;
	kmem_cache_free(drc_slab, rp);
}

int nfsd_reply_cache_init(void)
{
	int			i;
	struct svc_cacherep	*rp;

	drc_slab = kmem_cache_create("nfsd_drc", sizeof(struct svc_cacherep),
					0, 0, NULL);
	if (!drc_slab)
		goto out_nomem;

	INIT_LIST_HEAD(&lru_head);
	i = CACHESIZE;
	num_drc_entries = 0;
	while (i) {
		rp = nfsd_reply_cache_alloc();
		if (!rp)
			goto out_nomem;
		++num_drc_entries;
		list_add(&rp->c_lru, &lru_head);
		i--;
	}

	cache_hash = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL);
	if (!cache_hash)
		goto out_nomem;

	cache_disabled = 0;
	return 0;
out_nomem:
	printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
	nfsd_reply_cache_shutdown();
	return -ENOMEM;
}

void nfsd_reply_cache_shutdown(void)
{
	struct svc_cacherep	*rp;

	while (!list_empty(&lru_head)) {
		rp = list_entry(lru_head.next, struct svc_cacherep, c_lru);
		nfsd_reply_cache_free_locked(rp);
	}

	cache_disabled = 1;

	kfree (cache_hash);
	cache_hash = NULL;

	if (drc_slab) {
		kmem_cache_destroy(drc_slab);
		drc_slab = NULL;
	}
}

/*
 * Move cache entry to end of LRU list
 */
static void
lru_put_end(struct svc_cacherep *rp)
{
	rp->c_timestamp = jiffies;
	list_move_tail(&rp->c_lru, &lru_head);
}

/*
 * Move a cache entry from one hash list to another
 */
static void
hash_refile(struct svc_cacherep *rp)
{
	hlist_del_init(&rp->c_hash);
	hlist_add_head(&rp->c_hash, cache_hash + request_hash(rp->c_xid));
}

static inline bool
nfsd_cache_entry_expired(struct svc_cacherep *rp)
{
	return rp->c_state != RC_INPROG &&
	       time_after(jiffies, rp->c_timestamp + RC_EXPIRE);
}

/*
 * Search the request hash for an entry that matches the given rqstp.
 * Must be called with cache_lock held. Returns the found entry or
 * NULL on failure.
 */
static struct svc_cacherep *
nfsd_cache_search(struct svc_rqst *rqstp)
{
	struct svc_cacherep	*rp;
	struct hlist_node	*hn;
	struct hlist_head 	*rh;
	__be32			xid = rqstp->rq_xid;
	u32			proto =  rqstp->rq_prot,
				vers = rqstp->rq_vers,
				proc = rqstp->rq_proc;

	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 &&
		    proto == rp->c_prot && vers == rp->c_vers &&
		    !nfsd_cache_entry_expired(rp) &&
		    rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) &&
		    rpc_get_port(svc_addr(rqstp)) == rpc_get_port((struct sockaddr *)&rp->c_addr))
			return rp;
	}
	return NULL;
}

/*
 * Try to find an entry matching the current call in the cache. When none
 * is found, we grab the oldest unlocked entry off the LRU list.
 * Note that no operation within the loop may sleep.
 */
int
nfsd_cache_lookup(struct svc_rqst *rqstp)
{
	struct svc_cacherep	*rp;
	__be32			xid = rqstp->rq_xid;
	u32			proto =  rqstp->rq_prot,
				vers = rqstp->rq_vers,
				proc = rqstp->rq_proc;
	unsigned long		age;
	int type = rqstp->rq_cachetype;
	int rtn;

	rqstp->rq_cacherep = NULL;
	if (cache_disabled || type == RC_NOCACHE) {
		nfsdstats.rcnocache++;
		return RC_DOIT;
	}

	spin_lock(&cache_lock);
	rtn = RC_DOIT;

	rp = nfsd_cache_search(rqstp);
	if (rp) {
		nfsdstats.rchits++;
		goto found_entry;
	}
	nfsdstats.rcmisses++;

	/* This loop shouldn't take more than a few iterations normally */
	{
	int	safe = 0;
	list_for_each_entry(rp, &lru_head, c_lru) {
		if (rp->c_state != RC_INPROG)
			break;
		if (safe++ > CACHESIZE) {
			printk("nfsd: loop in repcache LRU list\n");
			cache_disabled = 1;
			goto out;
		}
	}
	}

	/* All entries on the LRU are in-progress. This should not happen */
	if (&rp->c_lru == &lru_head) {
		static int	complaints;

		printk(KERN_WARNING "nfsd: all repcache entries locked!\n");
		if (++complaints > 5) {
			printk(KERN_WARNING "nfsd: disabling repcache.\n");
			cache_disabled = 1;
		}
		goto out;
	}

	rqstp->rq_cacherep = rp;
	rp->c_state = RC_INPROG;
	rp->c_xid = xid;
	rp->c_proc = proc;
	rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
	rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
	rp->c_prot = proto;
	rp->c_vers = vers;

	hash_refile(rp);
	lru_put_end(rp);

	/* release any buffer */
	if (rp->c_type == RC_REPLBUFF) {
		kfree(rp->c_replvec.iov_base);
		rp->c_replvec.iov_base = NULL;
	}
	rp->c_type = RC_NOCACHE;
 out:
	spin_unlock(&cache_lock);
	return rtn;

found_entry:
	/* We found a matching entry which is either in progress or done. */
	age = jiffies - rp->c_timestamp;
	lru_put_end(rp);

	rtn = RC_DROPIT;
	/* Request being processed or excessive rexmits */
	if (rp->c_state == RC_INPROG || age < RC_DELAY)
		goto out;

	/* From the hall of fame of impractical attacks:
	 * Is this a user who tries to snoop on the cache? */
	rtn = RC_DOIT;
	if (!rqstp->rq_secure && rp->c_secure)
		goto out;

	/* Compose RPC reply header */
	switch (rp->c_type) {
	case RC_NOCACHE:
		break;
	case RC_REPLSTAT:
		svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
		rtn = RC_REPLY;
		break;
	case RC_REPLBUFF:
		if (!nfsd_cache_append(rqstp, &rp->c_replvec))
			goto out;	/* should not happen */
		rtn = RC_REPLY;
		break;
	default:
		printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
		rp->c_state = RC_UNUSED;
	}

	goto out;
}

/*
 * Update a cache entry. This is called from nfsd_dispatch when
 * the procedure has been executed and the complete reply is in
 * rqstp->rq_res.
 *
 * We're copying around data here rather than swapping buffers because
 * the toplevel loop requires max-sized buffers, which would be a waste
 * of memory for a cache with a max reply size of 100 bytes (diropokres).
 *
 * If we should start to use different types of cache entries tailored
 * specifically for attrstat and fh's, we may save even more space.
 *
 * Also note that a cachetype of RC_NOCACHE can legally be passed when
 * nfsd failed to encode a reply that otherwise would have been cached.
 * In this case, nfsd_cache_update is called with statp == NULL.
 */
void
nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
{
	struct svc_cacherep *rp;
	struct kvec	*resv = &rqstp->rq_res.head[0], *cachv;
	int		len;

	if (!(rp = rqstp->rq_cacherep) || cache_disabled)
		return;

	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;
		return;
	}

	switch (cachetype) {
	case RC_REPLSTAT:
		if (len != 1)
			printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
		rp->c_replstat = *statp;
		break;
	case RC_REPLBUFF:
		cachv = &rp->c_replvec;
		cachv->iov_base = kmalloc(len << 2, GFP_KERNEL);
		if (!cachv->iov_base) {
			rp->c_state = RC_UNUSED;
			return;
		}
		cachv->iov_len = len << 2;
		memcpy(cachv->iov_base, statp, len << 2);
		break;
	}
	spin_lock(&cache_lock);
	lru_put_end(rp);
	rp->c_secure = rqstp->rq_secure;
	rp->c_type = cachetype;
	rp->c_state = RC_DONE;
	spin_unlock(&cache_lock);
	return;
}

/*
 * Copy cached reply to current reply buffer. Should always fit.
 * FIXME as reply is in a page, we should just attach the page, and
 * keep a refcount....
 */
static int
nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
{
	struct kvec	*vec = &rqstp->rq_res.head[0];

	if (vec->iov_len + data->iov_len > PAGE_SIZE) {
		printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n",
				data->iov_len);
		return 0;
	}
	memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
	vec->iov_len += data->iov_len;
	return 1;
}
Commit	Line	Data
1da177e4	1	/*
1da177e4 LT	2	* Request reply cache. This is currently a global cache, but this may
	3	* change in the future and be a per-client cache.
	4	*
	5	* This code is heavily inspired by the 44BSD implementation, although
	6	* it does things a bit differently.
	7	*
	8	* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
	9	*/
	10
5a0e3ad6	11	#include <linux/slab.h>
7b9e8522	12	#include <linux/sunrpc/clnt.h>
5a0e3ad6	13
9a74af21 BH	14	#include "nfsd.h"
9a74af21 BH	15	#include "cache.h"
1da177e4 LT	16
	17	/* Size of reply cache. Common values are:
	18	* 4.3BSD: 128
	19	* 4.4BSD: 256
	20	* Solaris2: 1024
	21	* DEC Unix: 512-4096
	22	*/
	23	#define CACHESIZE 1024
	24	#define HASHSIZE 64
1da177e4	25
fca4217c	26	static struct hlist_head * cache_hash;
1da177e4 LT	27	static struct list_head lru_head;
1da177e4 LT	28	static int cache_disabled = 1;
8a8bc40d	29	static struct kmem_cache *drc_slab;
0ee0bf7e	30	static unsigned int num_drc_entries;
1da177e4	31
fca4217c GB	32	/*
	33	* Calculate the hash index from an XID.
	34	*/
	35	static inline u32 request_hash(u32 xid)
	36	{
	37	u32 h = xid;
	38	h ^= (xid >> 24);
	39	return h & (HASHSIZE-1);
	40	}
	41
1da177e4 LT	42	static int nfsd_cache_append(struct svc_rqst rqstp, struct kvec vec);
1da177e4 LT	43
fca4217c	44	/*
1da177e4 LT	45	* locking for the reply cache:
	46	* A cache entry is "single use" if c_state == RC_INPROG
	47	* Otherwise, it when accessing _prev or _next, the lock must be held.
	48	*/
	49	static DEFINE_SPINLOCK(cache_lock);
	50
f09841fd JL	51	static struct svc_cacherep *
f09841fd JL	52	nfsd_reply_cache_alloc(void)
1da177e4 LT	53	{
1da177e4 LT	54	struct svc_cacherep *rp;
f09841fd JL	55
	56	rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
	57	if (rp) {
	58	rp->c_state = RC_UNUSED;
	59	rp->c_type = RC_NOCACHE;
	60	INIT_LIST_HEAD(&rp->c_lru);
	61	INIT_HLIST_NODE(&rp->c_hash);
	62	}
	63	return rp;
	64	}
	65
	66	static void
	67	nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
	68	{
25e6b8b0	69	if (rp->c_type == RC_REPLBUFF)
f09841fd JL	70	kfree(rp->c_replvec.iov_base);
f09841fd JL	71	list_del(&rp->c_lru);
0ee0bf7e	72	--num_drc_entries;
f09841fd JL	73	kmem_cache_free(drc_slab, rp);
	74	}
	75
	76	int nfsd_reply_cache_init(void)
	77	{
1da177e4	78	int i;
f09841fd	79	struct svc_cacherep *rp;
1da177e4	80
8a8bc40d JL	81	drc_slab = kmem_cache_create("nfsd_drc", sizeof(struct svc_cacherep),
	82	0, 0, NULL);
	83	if (!drc_slab)
	84	goto out_nomem;
	85
1da177e4 LT	86	INIT_LIST_HEAD(&lru_head);
1da177e4 LT	87	i = CACHESIZE;
0ee0bf7e	88	num_drc_entries = 0;
d5c3428b	89	while (i) {
f09841fd	90	rp = nfsd_reply_cache_alloc();
d5c3428b BF	91	if (!rp)
d5c3428b BF	92	goto out_nomem;
0ee0bf7e	93	++num_drc_entries;
1da177e4	94	list_add(&rp->c_lru, &lru_head);
1da177e4 LT	95	i--;
	96	}
	97
fca4217c GB	98	cache_hash = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL);
fca4217c GB	99	if (!cache_hash)
d5c3428b	100	goto out_nomem;
1da177e4 LT	101
1da177e4 LT	102	cache_disabled = 0;
d5c3428b BF	103	return 0;
	104	out_nomem:
	105	printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
	106	nfsd_reply_cache_shutdown();
	107	return -ENOMEM;
1da177e4 LT	108	}
1da177e4 LT	109
d5c3428b	110	void nfsd_reply_cache_shutdown(void)
1da177e4 LT	111	{
	112	struct svc_cacherep *rp;
	113
	114	while (!list_empty(&lru_head)) {
	115	rp = list_entry(lru_head.next, struct svc_cacherep, c_lru);
f09841fd	116	nfsd_reply_cache_free_locked(rp);
1da177e4 LT	117	}
	118
	119	cache_disabled = 1;
	120
fca4217c GB	121	kfree (cache_hash);
fca4217c GB	122	cache_hash = NULL;
8a8bc40d JL	123
	124	if (drc_slab) {
	125	kmem_cache_destroy(drc_slab);
	126	drc_slab = NULL;
	127	}
1da177e4 LT	128	}
	129
	130	/*
	131	* Move cache entry to end of LRU list
	132	*/
	133	static void
	134	lru_put_end(struct svc_cacherep *rp)
	135	{
56c2548b	136	rp->c_timestamp = jiffies;
f116629d	137	list_move_tail(&rp->c_lru, &lru_head);
1da177e4 LT	138	}
	139
	140	/*
	141	* Move a cache entry from one hash list to another
	142	*/
	143	static void
	144	hash_refile(struct svc_cacherep *rp)
	145	{
	146	hlist_del_init(&rp->c_hash);
fca4217c	147	hlist_add_head(&rp->c_hash, cache_hash + request_hash(rp->c_xid));
1da177e4 LT	148	}
1da177e4 LT	149
d1a0774d JL	150	static inline bool
	151	nfsd_cache_entry_expired(struct svc_cacherep *rp)
	152	{
	153	return rp->c_state != RC_INPROG &&
	154	time_after(jiffies, rp->c_timestamp + RC_EXPIRE);
	155	}
	156
a4a3ec32 JL	157	/*
	158	* Search the request hash for an entry that matches the given rqstp.
	159	* Must be called with cache_lock held. Returns the found entry or
	160	* NULL on failure.
	161	*/
	162	static struct svc_cacherep *
	163	nfsd_cache_search(struct svc_rqst *rqstp)
	164	{
	165	struct svc_cacherep *rp;
	166	struct hlist_node *hn;
	167	struct hlist_head *rh;
	168	__be32 xid = rqstp->rq_xid;
	169	u32 proto = rqstp->rq_prot,
	170	vers = rqstp->rq_vers,
	171	proc = rqstp->rq_proc;
	172
	173	rh = &cache_hash[request_hash(xid)];
	174	hlist_for_each_entry(rp, hn, rh, c_hash) {
	175	if (rp->c_state != RC_UNUSED &&
	176	xid == rp->c_xid && proc == rp->c_proc &&
	177	proto == rp->c_prot && vers == rp->c_vers &&
	178	!nfsd_cache_entry_expired(rp) &&
	179	rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) &&
	180	rpc_get_port(svc_addr(rqstp)) == rpc_get_port((struct sockaddr *)&rp->c_addr))
	181	return rp;
	182	}
	183	return NULL;
	184	}
	185
1da177e4 LT	186	/*
	187	* Try to find an entry matching the current call in the cache. When none
	188	* is found, we grab the oldest unlocked entry off the LRU list.
	189	* Note that no operation within the loop may sleep.
	190	*/
	191	int
1091006c	192	nfsd_cache_lookup(struct svc_rqst *rqstp)
1da177e4	193	{
1da177e4	194	struct svc_cacherep *rp;
c7afef1f AV	195	__be32 xid = rqstp->rq_xid;
c7afef1f AV	196	u32 proto = rqstp->rq_prot,
1da177e4 LT	197	vers = rqstp->rq_vers,
	198	proc = rqstp->rq_proc;
	199	unsigned long age;
1091006c	200	int type = rqstp->rq_cachetype;
1da177e4 LT	201	int rtn;
	202
	203	rqstp->rq_cacherep = NULL;
	204	if (cache_disabled \|\| type == RC_NOCACHE) {
	205	nfsdstats.rcnocache++;
	206	return RC_DOIT;
	207	}
	208
	209	spin_lock(&cache_lock);
	210	rtn = RC_DOIT;
	211
a4a3ec32 JL	212	rp = nfsd_cache_search(rqstp);
	213	if (rp) {
	214	nfsdstats.rchits++;
	215	goto found_entry;
1da177e4 LT	216	}
	217	nfsdstats.rcmisses++;
	218
	219	/* This loop shouldn't take more than a few iterations normally */
	220	{
	221	int safe = 0;
	222	list_for_each_entry(rp, &lru_head, c_lru) {
	223	if (rp->c_state != RC_INPROG)
	224	break;
	225	if (safe++ > CACHESIZE) {
	226	printk("nfsd: loop in repcache LRU list\n");
	227	cache_disabled = 1;
	228	goto out;
	229	}
	230	}
	231	}
	232
cf0a586c GB	233	/* All entries on the LRU are in-progress. This should not happen */
cf0a586c GB	234	if (&rp->c_lru == &lru_head) {
1da177e4 LT	235	static int complaints;
	236
	237	printk(KERN_WARNING "nfsd: all repcache entries locked!\n");
	238	if (++complaints > 5) {
	239	printk(KERN_WARNING "nfsd: disabling repcache.\n");
	240	cache_disabled = 1;
	241	}
	242	goto out;
	243	}
	244
	245	rqstp->rq_cacherep = rp;
	246	rp->c_state = RC_INPROG;
	247	rp->c_xid = xid;
	248	rp->c_proc = proc;
7b9e8522 JL	249	rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
7b9e8522 JL	250	rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
1da177e4 LT	251	rp->c_prot = proto;
1da177e4 LT	252	rp->c_vers = vers;
1da177e4 LT	253
1da177e4 LT	254	hash_refile(rp);
56c2548b	255	lru_put_end(rp);
1da177e4 LT	256
	257	/* release any buffer */
	258	if (rp->c_type == RC_REPLBUFF) {
	259	kfree(rp->c_replvec.iov_base);
	260	rp->c_replvec.iov_base = NULL;
	261	}
	262	rp->c_type = RC_NOCACHE;
	263	out:
	264	spin_unlock(&cache_lock);
	265	return rtn;
	266
	267	found_entry:
	268	/* We found a matching entry which is either in progress or done. */
	269	age = jiffies - rp->c_timestamp;
1da177e4 LT	270	lru_put_end(rp);
	271
	272	rtn = RC_DROPIT;
	273	/* Request being processed or excessive rexmits */
	274	if (rp->c_state == RC_INPROG \|\| age < RC_DELAY)
	275	goto out;
	276
	277	/* From the hall of fame of impractical attacks:
	278	* Is this a user who tries to snoop on the cache? */
	279	rtn = RC_DOIT;
	280	if (!rqstp->rq_secure && rp->c_secure)
	281	goto out;
	282
	283	/* Compose RPC reply header */
	284	switch (rp->c_type) {
	285	case RC_NOCACHE:
	286	break;
	287	case RC_REPLSTAT:
	288	svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
	289	rtn = RC_REPLY;
	290	break;
	291	case RC_REPLBUFF:
	292	if (!nfsd_cache_append(rqstp, &rp->c_replvec))
	293	goto out; /* should not happen */
	294	rtn = RC_REPLY;
	295	break;
	296	default:
	297	printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
	298	rp->c_state = RC_UNUSED;
	299	}
	300
	301	goto out;
	302	}
	303
	304	/*
	305	* Update a cache entry. This is called from nfsd_dispatch when
	306	* the procedure has been executed and the complete reply is in
	307	* rqstp->rq_res.
	308	*
	309	* We're copying around data here rather than swapping buffers because
	310	* the toplevel loop requires max-sized buffers, which would be a waste
	311	* of memory for a cache with a max reply size of 100 bytes (diropokres).
	312	*
	313	* If we should start to use different types of cache entries tailored
	314	* specifically for attrstat and fh's, we may save even more space.
	315	*
	316	* Also note that a cachetype of RC_NOCACHE can legally be passed when
	317	* nfsd failed to encode a reply that otherwise would have been cached.
	318	* In this case, nfsd_cache_update is called with statp == NULL.
	319	*/
	320	void
c7afef1f	321	nfsd_cache_update(struct svc_rqst rqstp, int cachetype, __be32 statp)
1da177e4 LT	322	{
	323	struct svc_cacherep *rp;
	324	struct kvec resv = &rqstp->rq_res.head[0], cachv;
	325	int len;
	326
	327	if (!(rp = rqstp->rq_cacherep) \|\| cache_disabled)
	328	return;
	329
	330	len = resv->iov_len - ((char)statp - (char)resv->iov_base);
	331	len >>= 2;
fca4217c	332
1da177e4 LT	333	/* Don't cache excessive amounts of data and XDR failures */
	334	if (!statp \|\| len > (256 >> 2)) {
	335	rp->c_state = RC_UNUSED;
	336	return;
	337	}
	338
	339	switch (cachetype) {
	340	case RC_REPLSTAT:
	341	if (len != 1)
	342	printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
	343	rp->c_replstat = *statp;
	344	break;
	345	case RC_REPLBUFF:
	346	cachv = &rp->c_replvec;
	347	cachv->iov_base = kmalloc(len << 2, GFP_KERNEL);
	348	if (!cachv->iov_base) {
1da177e4	349	rp->c_state = RC_UNUSED;
1da177e4 LT	350	return;
	351	}
	352	cachv->iov_len = len << 2;
	353	memcpy(cachv->iov_base, statp, len << 2);
	354	break;
	355	}
	356	spin_lock(&cache_lock);
	357	lru_put_end(rp);
	358	rp->c_secure = rqstp->rq_secure;
	359	rp->c_type = cachetype;
	360	rp->c_state = RC_DONE;
1da177e4 LT	361	spin_unlock(&cache_lock);
	362	return;
	363	}
	364
	365	/*
	366	* Copy cached reply to current reply buffer. Should always fit.
	367	* FIXME as reply is in a page, we should just attach the page, and
	368	* keep a refcount....
	369	*/
	370	static int
	371	nfsd_cache_append(struct svc_rqst rqstp, struct kvec data)
	372	{
	373	struct kvec *vec = &rqstp->rq_res.head[0];
	374
	375	if (vec->iov_len + data->iov_len > PAGE_SIZE) {
	376	printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n",
	377	data->iov_len);
	378	return 0;
	379	}
	380	memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
	381	vec->iov_len += data->iov_len;
	382	return 1;
	383	}