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SUNRPC: Clean up the AUTH cache code

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Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2018-10-11 16:11:09 -04:00
parent 86bbd7422a
commit 95cd623250
2 changed files with 87 additions and 62 deletions
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147
net/sunrpc/auth.c
View File

@ -291,25 +291,30 @@ rpcauth_release(struct rpc_auth *auth)
static DEFINE_SPINLOCK(rpc_credcache_lock);
static void
/*
* On success, the caller is responsible for freeing the reference
* held by the hashtable
*/
static bool
rpcauth_unhash_cred_locked(struct rpc_cred *cred)
{
if (!test_and_clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
return false;
hlist_del_rcu(&cred->cr_hash);
smp_mb__before_atomic();
clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
return true;
}
static int
static bool
rpcauth_unhash_cred(struct rpc_cred *cred)
{
spinlock_t *cache_lock;
int ret;
bool ret;
if (!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
return false;
cache_lock = &cred->cr_auth->au_credcache->lock;
spin_lock(cache_lock);
ret = atomic_read(&cred->cr_count) == 0;
if (ret)
rpcauth_unhash_cred_locked(cred);
ret = rpcauth_unhash_cred_locked(cred);
spin_unlock(cache_lock);
return ret;
}
@ -388,6 +393,44 @@ void rpcauth_destroy_credlist(struct list_head *head)
}
}
static void
rpcauth_lru_add_locked(struct rpc_cred *cred)
{
if (!list_empty(&cred->cr_lru))
return;
number_cred_unused++;
list_add_tail(&cred->cr_lru, &cred_unused);
}
static void
rpcauth_lru_add(struct rpc_cred *cred)
{
if (!list_empty(&cred->cr_lru))
return;
spin_lock(&rpc_credcache_lock);
rpcauth_lru_add_locked(cred);
spin_unlock(&rpc_credcache_lock);
}
static void
rpcauth_lru_remove_locked(struct rpc_cred *cred)
{
if (list_empty(&cred->cr_lru))
return;
number_cred_unused--;
list_del_init(&cred->cr_lru);
}
static void
rpcauth_lru_remove(struct rpc_cred *cred)
{
if (list_empty(&cred->cr_lru))
return;
spin_lock(&rpc_credcache_lock);
rpcauth_lru_remove_locked(cred);
spin_unlock(&rpc_credcache_lock);
}
/*
* Clear the RPC credential cache, and delete those credentials
* that are not referenced.
@ -407,13 +450,10 @@ rpcauth_clear_credcache(struct rpc_cred_cache *cache)
head = &cache->hashtable[i];
while (!hlist_empty(head)) {
cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
get_rpccred(cred);
if (!list_empty(&cred->cr_lru)) {
list_del(&cred->cr_lru);
number_cred_unused--;
}
list_add_tail(&cred->cr_lru, &free);
rpcauth_unhash_cred_locked(cred);
/* Note: We now hold a reference to cred */
rpcauth_lru_remove_locked(cred);
list_add_tail(&cred->cr_lru, &free);
}
}
spin_unlock(&cache->lock);
@ -447,7 +487,6 @@ EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
static long
rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
{
spinlock_t *cache_lock;
struct rpc_cred *cred, *next;
unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
long freed = 0;
@ -456,32 +495,24 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
if (nr_to_scan-- == 0)
break;
if (atomic_read(&cred->cr_count) > 1) {
rpcauth_lru_remove_locked(cred);
continue;
}
/*
* Enforce a 60 second garbage collection moratorium
* Note that the cred_unused list must be time-ordered.
*/
if (time_in_range(cred->cr_expire, expired, jiffies) &&
test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
freed = SHRINK_STOP;
break;
}
list_del_init(&cred->cr_lru);
number_cred_unused--;
freed++;
if (atomic_read(&cred->cr_count) != 0)
if (!time_in_range(cred->cr_expire, expired, jiffies))
continue;
if (!rpcauth_unhash_cred(cred))
continue;
cache_lock = &cred->cr_auth->au_credcache->lock;
spin_lock(cache_lock);
if (atomic_read(&cred->cr_count) == 0) {
get_rpccred(cred);
list_add_tail(&cred->cr_lru, free);
rpcauth_unhash_cred_locked(cred);
}
spin_unlock(cache_lock);
rpcauth_lru_remove_locked(cred);
freed++;
list_add_tail(&cred->cr_lru, free);
}
return freed;
return freed ? freed : SHRINK_STOP;
}
static unsigned long
@ -595,6 +626,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
if (cred == NULL) {
cred = new;
set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
atomic_inc(&cred->cr_count);
hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
} else
list_add_tail(&new->cr_lru, &free);
@ -709,36 +741,29 @@ put_rpccred(struct rpc_cred *cred)
{
if (cred == NULL)
return;
/* Fast path for unhashed credentials */
if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
rcu_read_lock();
if (atomic_dec_and_test(&cred->cr_count))
goto destroy;
if (atomic_read(&cred->cr_count) != 1 ||
!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
goto out;
if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
cred->cr_expire = jiffies;
rpcauth_lru_add(cred);
/* Race breaker */
if (unlikely(!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags)))
rpcauth_lru_remove(cred);
} else if (rpcauth_unhash_cred(cred)) {
rpcauth_lru_remove(cred);
if (atomic_dec_and_test(&cred->cr_count))
cred->cr_ops->crdestroy(cred);
return;
goto destroy;
}
if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
return;
if (!list_empty(&cred->cr_lru)) {
number_cred_unused--;
list_del_init(&cred->cr_lru);
}
if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
cred->cr_expire = jiffies;
list_add_tail(&cred->cr_lru, &cred_unused);
number_cred_unused++;
goto out_nodestroy;
}
if (!rpcauth_unhash_cred(cred)) {
/* We were hashed and someone looked us up... */
goto out_nodestroy;
}
}
spin_unlock(&rpc_credcache_lock);
cred->cr_ops->crdestroy(cred);
out:
rcu_read_unlock();
return;
out_nodestroy:
spin_unlock(&rpc_credcache_lock);
destroy:
rcu_read_unlock();
cred->cr_ops->crdestroy(cred);
}
EXPORT_SYMBOL_GPL(put_rpccred);

2
net/sunrpc/auth_null.c
View File

@ -138,6 +138,6 @@ struct rpc_cred null_cred = {
.cr_lru = LIST_HEAD_INIT(null_cred.cr_lru),
.cr_auth = &null_auth,
.cr_ops = &null_credops,
.cr_count = ATOMIC_INIT(1),
.cr_count = ATOMIC_INIT(2),
.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE,
};