/*
* 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);
