linux/fs/nfs/pnfs_dev.c
Trond Myklebust 1d92a08da2 NFSv4.1: Fix a refcounting issue in the pNFS device id cache
When we add something to the global device id cache, we need to bump the
reference count, so that the cache itself holds a reference.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-06-15 11:24:29 -04:00

278 lines
7.2 KiB
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;
}
static struct nfs4_deviceid_node *
_lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id,
long hash)
{
struct nfs4_deviceid_node *d;
struct hlist_node *n;
hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
if (d->ld == ld && d->nfs_client == clp &&
!memcmp(&d->deviceid, id, sizeof(*id))) {
if (atomic_read(&d->ref))
return d;
else
continue;
}
return NULL;
}
/*
* 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 *
_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id,
long hash)
{
struct nfs4_deviceid_node *d;
rcu_read_lock();
d = _lookup_deviceid(ld, clp, id, hash);
if (d && !atomic_inc_not_zero(&d->ref))
d = NULL;
rcu_read_unlock();
return d;
}
struct nfs4_deviceid_node *
nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
return _find_get_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
}
EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
/*
* Unhash and put deviceid
*
* @clp nfs_client associated with deviceid
* @id the deviceid to unhash
*
* @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
*/
struct nfs4_deviceid_node *
nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
struct nfs4_deviceid_node *d;
spin_lock(&nfs4_deviceid_lock);
rcu_read_lock();
d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
rcu_read_unlock();
if (!d) {
spin_unlock(&nfs4_deviceid_lock);
return NULL;
}
hlist_del_init_rcu(&d->node);
spin_unlock(&nfs4_deviceid_lock);
synchronize_rcu();
/* balance the initial ref set in pnfs_insert_deviceid */
if (atomic_dec_and_test(&d->ref))
return d;
return NULL;
}
EXPORT_SYMBOL_GPL(nfs4_unhash_put_deviceid);
/*
* Delete a deviceid from cache
*
* @clp struct nfs_client qualifying the deviceid
* @id deviceid to delete
*/
void
nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
struct nfs4_deviceid_node *d;
d = nfs4_unhash_put_deviceid(ld, clp, id);
if (!d)
return;
d->ld->free_deviceid_node(d);
}
EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
void
nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *nfs_client,
const struct nfs4_deviceid *id)
{
INIT_HLIST_NODE(&d->node);
INIT_HLIST_NODE(&d->tmpnode);
d->ld = ld;
d->nfs_client = nfs_client;
d->deviceid = *id;
atomic_set(&d->ref, 1);
}
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 the following members:
* new->ld
* new->nfs_client
* 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);
hash = nfs4_deviceid_hash(&new->deviceid);
d = _find_get_deviceid(new->ld, new->nfs_client, &new->deviceid, hash);
if (d) {
spin_unlock(&nfs4_deviceid_lock);
return d;
}
hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
spin_unlock(&nfs4_deviceid_lock);
atomic_inc(&new->ref);
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();
d->ld->free_deviceid_node(d);
return true;
}
EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
static void
_deviceid_purge_client(const struct nfs_client *clp, long hash)
{
struct nfs4_deviceid_node *d;
struct hlist_node *n;
HLIST_HEAD(tmp);
spin_lock(&nfs4_deviceid_lock);
rcu_read_lock();
hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
if (d->nfs_client == clp && atomic_read(&d->ref)) {
hlist_del_init_rcu(&d->node);
hlist_add_head(&d->tmpnode, &tmp);
}
rcu_read_unlock();
spin_unlock(&nfs4_deviceid_lock);
if (hlist_empty(&tmp))
return;
synchronize_rcu();
while (!hlist_empty(&tmp)) {
d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
hlist_del(&d->tmpnode);
if (atomic_dec_and_test(&d->ref))
d->ld->free_deviceid_node(d);
}
}
void
nfs4_deviceid_purge_client(const struct nfs_client *clp)
{
long h;
if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
return;
for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
_deviceid_purge_client(clp, h);
}