[deliverable/linux.git] / fs / nfs / pnfs_dev.c

/*
 *  Device operations for the pnfs client.
 *
 *  Copyright (c) 2002
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <dhildebz@umich.edu>
 *  Garth Goodson   <Garth.Goodson@netapp.com>
 *
 *  Permission is granted to use, copy, create derivative works, and
 *  redistribute this software and such derivative works for any purpose,
 *  so long as the name of the University of Michigan is not used in
 *  any advertising or publicity pertaining to the use or distribution
 *  of this software without specific, written prior authorization. If
 *  the above copyright notice or any other identification of the
 *  University of Michigan is included in any copy of any portion of
 *  this software, then the disclaimer below must also be included.
 *
 *  This software is provided as is, without representation or warranty
 *  of any kind either express or implied, including without limitation
 *  the implied warranties of merchantability, fitness for a particular
 *  purpose, or noninfringement.  The Regents of the University of
 *  Michigan shall not be liable for any damages, including special,
 *  indirect, incidental, or consequential damages, with respect to any
 *  claim arising out of or in connection with the use of the software,
 *  even if it has been or is hereafter advised of the possibility of
 *  such damages.
 */

#include "pnfs.h"

#define NFSDBG_FACILITY		NFSDBG_PNFS

/*
 * Device ID RCU cache. A device ID is unique per server and layout type.
 */
#define NFS4_DEVICE_ID_HASH_BITS	5
#define NFS4_DEVICE_ID_HASH_SIZE	(1 << NFS4_DEVICE_ID_HASH_BITS)
#define NFS4_DEVICE_ID_HASH_MASK	(NFS4_DEVICE_ID_HASH_SIZE - 1)

static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
static DEFINE_SPINLOCK(nfs4_deviceid_lock);

void
nfs4_print_deviceid(const struct nfs4_deviceid *id)
{
	u32 *p = (u32 *)id;

	dprintk("%s: device id= [%x%x%x%x]\n", __func__,
		p[0], p[1], p[2], p[3]);
}
EXPORT_SYMBOL_GPL(nfs4_print_deviceid);

static inline u32
nfs4_deviceid_hash(const struct nfs4_deviceid *id)
{
	unsigned char *cptr = (unsigned char *)id->data;
	unsigned int nbytes = NFS4_DEVICEID4_SIZE;
	u32 x = 0;

	while (nbytes--) {
		x *= 37;
		x += *cptr++;
	}
	return x & NFS4_DEVICE_ID_HASH_MASK;
}

/*
 * Lookup a deviceid in cache and get a reference count on it if found
 *
 * @clp nfs_client associated with deviceid
 * @id deviceid to look up
 */
struct nfs4_deviceid_node *
nfs4_find_get_deviceid(const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
	struct nfs4_deviceid_node *d;
	struct hlist_node *n;
	long hash = nfs4_deviceid_hash(id);

	rcu_read_lock();
	hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node) {
		if (d->nfs_client == clp && !memcmp(&d->deviceid, id, sizeof(*id))) {
			if (!atomic_inc_not_zero(&d->ref))
				goto fail;
			rcu_read_unlock();
			return d;
		}
	}
fail:
	rcu_read_unlock();
	return NULL;
}
EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);

void
nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
			const struct nfs_client *nfs_client,
			const struct nfs4_deviceid *id)
{
	d->nfs_client = nfs_client;
	d->deviceid = *id;
}
EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);

/*
 * Uniquely initialize and insert a deviceid node into cache
 *
 * @new new deviceid node
 *      Note that the caller must set up new->nfs_client and new->deviceid
 *
 * @ret the inserted node, if none found, otherwise, the found entry.
 */
struct nfs4_deviceid_node *
nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
{
	struct nfs4_deviceid_node *d;
	long hash;

	spin_lock(&nfs4_deviceid_lock);
	d = nfs4_find_get_deviceid(new->nfs_client, &new->deviceid);
	if (d) {
		spin_unlock(&nfs4_deviceid_lock);
		return d;
	}

	INIT_HLIST_NODE(&new->node);
	atomic_set(&new->ref, 1);
	hash = nfs4_deviceid_hash(&new->deviceid);
	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
	spin_unlock(&nfs4_deviceid_lock);

	return new;
}
EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);

/*
 * Dereference a deviceid node and delete it when its reference count drops
 * to zero.
 *
 * @d deviceid node to put
 *
 * @ret true iff the node was deleted
 */
bool
nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
{
	if (!atomic_dec_and_lock(&d->ref, &nfs4_deviceid_lock))
		return false;
	hlist_del_init_rcu(&d->node);
	spin_unlock(&nfs4_deviceid_lock);
	synchronize_rcu();
	return true;
}
EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
Commit	Line	Data
a1eaecbc BH	1	/*
	2	* Device operations for the pnfs client.
	3	*
	4	* Copyright (c) 2002
	5	* The Regents of the University of Michigan
	6	* All Rights Reserved
	7	*
	8	* Dean Hildebrand <dhildebz@umich.edu>
	9	* Garth Goodson <Garth.Goodson@netapp.com>
	10	*
	11	* Permission is granted to use, copy, create derivative works, and
	12	* redistribute this software and such derivative works for any purpose,
	13	* so long as the name of the University of Michigan is not used in
	14	* any advertising or publicity pertaining to the use or distribution
	15	* of this software without specific, written prior authorization. If
	16	* the above copyright notice or any other identification of the
	17	* University of Michigan is included in any copy of any portion of
	18	* this software, then the disclaimer below must also be included.
	19	*
	20	* This software is provided as is, without representation or warranty
	21	* of any kind either express or implied, including without limitation
	22	* the implied warranties of merchantability, fitness for a particular
	23	* purpose, or noninfringement. The Regents of the University of
	24	* Michigan shall not be liable for any damages, including special,
	25	* indirect, incidental, or consequential damages, with respect to any
	26	* claim arising out of or in connection with the use of the software,
	27	* even if it has been or is hereafter advised of the possibility of
	28	* such damages.
	29	*/
	30
	31	#include "pnfs.h"
	32
	33	#define NFSDBG_FACILITY NFSDBG_PNFS
	34
	35	/*
	36	* Device ID RCU cache. A device ID is unique per server and layout type.
	37	*/
	38	#define NFS4_DEVICE_ID_HASH_BITS 5
	39	#define NFS4_DEVICE_ID_HASH_SIZE (1 << NFS4_DEVICE_ID_HASH_BITS)
	40	#define NFS4_DEVICE_ID_HASH_MASK (NFS4_DEVICE_ID_HASH_SIZE - 1)
	41
	42	static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
	43	static DEFINE_SPINLOCK(nfs4_deviceid_lock);
	44
	45	void
	46	nfs4_print_deviceid(const struct nfs4_deviceid *id)
	47	{
	48	u32 p = (u32 )id;
	49
	50	dprintk("%s: device id= [%x%x%x%x]\n", __func__,
	51	p[0], p[1], p[2], p[3]);
	52	}
	53	EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
	54
	55	static inline u32
	56	nfs4_deviceid_hash(const struct nfs4_deviceid *id)
	57	{
	58	unsigned char cptr = (unsigned char )id->data;
	59	unsigned int nbytes = NFS4_DEVICEID4_SIZE;
	60	u32 x = 0;
	61
	62	while (nbytes--) {
	63	x *= 37;
	64	x += *cptr++;
65	}
66	return x & NFS4_DEVICE_ID_HASH_MASK;
67	}
68
69	/*
70	* Lookup a deviceid in cache and get a reference count on it if found
71	*
72	* @clp nfs_client associated with deviceid
73	* @id deviceid to look up
74	*/
75	struct nfs4_deviceid_node *
76	nfs4_find_get_deviceid(const struct nfs_client clp, const struct nfs4_deviceid id)
77	{
78	struct nfs4_deviceid_node *d;
79	struct hlist_node *n;
80	long hash = nfs4_deviceid_hash(id);
81
82	rcu_read_lock();
83	hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node) {
84	if (d->nfs_client == clp && !memcmp(&d->deviceid, id, sizeof(*id))) {
85	if (!atomic_inc_not_zero(&d->ref))
86	goto fail;
87	rcu_read_unlock();
88	return d;
89	}
90	}
91	fail:
92	rcu_read_unlock();
93	return NULL;
94	}
95	EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
96
97	void
98	nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
99	const struct nfs_client *nfs_client,
100	const struct nfs4_deviceid *id)
101	{
102	d->nfs_client = nfs_client;
103	d->deviceid = *id;
104	}
105	EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);
106
107	/*
108	* Uniquely initialize and insert a deviceid node into cache
109	*
110	* @new new deviceid node
111	* Note that the caller must set up new->nfs_client and new->deviceid
112	*
113	* @ret the inserted node, if none found, otherwise, the found entry.
114	*/
115	struct nfs4_deviceid_node *
116	nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
117	{
118	struct nfs4_deviceid_node *d;
119	long hash;
120
121	spin_lock(&nfs4_deviceid_lock);
122	d = nfs4_find_get_deviceid(new->nfs_client, &new->deviceid);
123	if (d) {
124	spin_unlock(&nfs4_deviceid_lock);
125	return d;
126	}
127
128	INIT_HLIST_NODE(&new->node);
129	atomic_set(&new->ref, 1);
130	hash = nfs4_deviceid_hash(&new->deviceid);
131	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
132	spin_unlock(&nfs4_deviceid_lock);
133
134	return new;
135	}
136	EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
137
138	/*
139	* Dereference a deviceid node and delete it when its reference count drops
140	* to zero.
141	*
142	* @d deviceid node to put
143	*
144	* @ret true iff the node was deleted
145	*/
146	bool
147	nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
148	{
149	if (!atomic_dec_and_lock(&d->ref, &nfs4_deviceid_lock))
150	return false;
151	hlist_del_init_rcu(&d->node);
152	spin_unlock(&nfs4_deviceid_lock);
153	synchronize_rcu();
154	return true;
155	}
156	EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);