Viewing: hash.c
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
* Copyright (c) 2011, 2016, Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
*
* Implement a hash class for hash process in lustre system.
*
* Author: YuZhangyong <yzy@clusterfs.com>
*
* 2008-08-15: Brian Behlendorf <behlendorf1@llnl.gov>
* - Simplified API and improved documentation
* - Added per-hash feature flags:
* * CFS_HASH_DEBUG additional validation
* * CFS_HASH_REHASH dynamic rehashing
* - Added per-hash statistics
* - General performance enhancements
*
* 2009-07-31: Liang Zhen <zhen.liang@sun.com>
* - move all stuff to libcfs
* - don't allow cur_bits != max_bits without setting of CFS_HASH_REHASH
* - ignore hs_rwlock if without CFS_HASH_REHASH setting
* - buckets are allocated one by one(instead of contiguous memory),
* to avoid unnecessary cacheline conflict
*
* 2010-03-01: Liang Zhen <zhen.liang@sun.com>
* - "bucket" is a group of hlist_head now, user can specify bucket size
* by bkt_bits of cfs_hash_create(), all hlist_heads in a bucket share
* one lock for reducing memory overhead.
*
* - support lockless hash, caller will take care of locks:
* avoid lock overhead for hash tables that are already protected
* by locking in the caller for another reason
*
* - support both spin_lock/rwlock for bucket:
* overhead of spinlock contention is lower than read/write
* contention of rwlock, so using spinlock to serialize operations on
* bucket is more reasonable for those frequently changed hash tables
*
* - support one-single lock mode:
* one lock to protect all hash operations to avoid overhead of
* multiple locks if hash table is always small
*
* - removed a lot of unnecessary addref & decref on hash element:
* addref & decref are atomic operations in many use-cases which
* are expensive.
*
* - support non-blocking cfs_hash_add() and cfs_hash_findadd():
* some lustre use-cases require these functions to be strictly
* non-blocking, we need to schedule required rehash on a different
* thread on those cases.
*
* - safer rehash on large hash table
* In old implementation, rehash function will exclusively lock the
* hash table and finish rehash in one batch, it's dangerous on SMP
* system because rehash millions of elements could take long time.
* New implemented rehash can release lock and relax CPU in middle
* of rehash, it's safe for another thread to search/change on the
* hash table even it's in rehasing.
*
* - support two different refcount modes
* . hash table has refcount on element
* . hash table doesn't change refcount on adding/removing element
*
* - support long name hash table (for param-tree)
*
* - fix a bug for cfs_hash_rehash_key:
* in old implementation, cfs_hash_rehash_key could screw up the
* hash-table because @key is overwritten without any protection.
* Now we need user to define hs_keycpy for those rehash enabled
* hash tables, cfs_hash_rehash_key will overwrite hash-key
* inside lock by calling hs_keycpy.
*
* - better hash iteration:
* Now we support both locked iteration & lockless iteration of hash
* table. Also, user can break the iteration by return 1 in callback.
*/
#include <linux/seq_file.h>
#include <linux/log2.h>
#include <cfs_hash.h>
#include <obd_class.h>
#if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
static unsigned int warn_on_depth = 8;
module_param(warn_on_depth, uint, 0644);
MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
#endif
static struct workqueue_struct *cfs_rehash_wq;
int cfs_hash_init(void)
{
int rc = 0;
cfs_rehash_wq = alloc_workqueue("cfs_rh", WQ_SYSFS, 4);
if (!cfs_rehash_wq) {
rc = -ENOMEM;
CERROR("obdclass: failed to start rehash workqueue: rc = %d\n",
rc);
}
return rc;
}
void cfs_hash_fini(void)
{
if (cfs_rehash_wq)
destroy_workqueue(cfs_rehash_wq);
}
static inline void
cfs_hash_nl_lock(union cfs_hash_lock *lock, int exclusive) {}
static inline void
cfs_hash_nl_unlock(union cfs_hash_lock *lock, int exclusive) {}
static inline void
cfs_hash_spin_lock(union cfs_hash_lock *lock, int exclusive)
__acquires(&lock->spin)
{
spin_lock(&lock->spin);
}
static inline void
cfs_hash_spin_unlock(union cfs_hash_lock *lock, int exclusive)
__releases(&lock->spin)
{
spin_unlock(&lock->spin);
}
static inline void
cfs_hash_rw_lock(union cfs_hash_lock *lock, int exclusive)
__acquires(&lock->rw)
{
if (!exclusive)
read_lock(&lock->rw);
else
write_lock(&lock->rw);
}
static inline void
cfs_hash_rw_unlock(union cfs_hash_lock *lock, int exclusive)
__releases(&lock->rw)
{
if (!exclusive)
read_unlock(&lock->rw);
else
write_unlock(&lock->rw);
}
static inline void
cfs_hash_rw_sem_lock(union cfs_hash_lock *lock, int exclusive)
__acquires(&lock->rw_sem)
{
if (!exclusive)
down_read(&lock->rw_sem);
else
down_write(&lock->rw_sem);
}
static inline void
cfs_hash_rw_sem_unlock(union cfs_hash_lock *lock, int exclusive)
__releases(&lock->rw_sem)
{
if (!exclusive)
up_read(&lock->rw_sem);
else
up_write(&lock->rw_sem);
}
/** No lock hash */
static struct cfs_hash_lock_ops cfs_hash_nl_lops = {
.hs_lock = cfs_hash_nl_lock,
.hs_unlock = cfs_hash_nl_unlock,
.hs_bkt_lock = cfs_hash_nl_lock,
.hs_bkt_unlock = cfs_hash_nl_unlock,
};
/** no bucket lock, one spinlock to protect everything */
static struct cfs_hash_lock_ops cfs_hash_nbl_lops = {
.hs_lock = cfs_hash_spin_lock,
.hs_unlock = cfs_hash_spin_unlock,
.hs_bkt_lock = cfs_hash_nl_lock,
.hs_bkt_unlock = cfs_hash_nl_unlock,
};
/** spin bucket lock, rehash is enabled */
static struct cfs_hash_lock_ops cfs_hash_bkt_spin_lops = {
.hs_lock = cfs_hash_rw_lock,
.hs_unlock = cfs_hash_rw_unlock,
.hs_bkt_lock = cfs_hash_spin_lock,
.hs_bkt_unlock = cfs_hash_spin_unlock,
};
/** rw bucket lock, rehash is enabled */
static struct cfs_hash_lock_ops cfs_hash_bkt_rw_lops = {
.hs_lock = cfs_hash_rw_lock,
.hs_unlock = cfs_hash_rw_unlock,
.hs_bkt_lock = cfs_hash_rw_lock,
.hs_bkt_unlock = cfs_hash_rw_unlock,
};
/** spin bucket lock, rehash is disabled */
static struct cfs_hash_lock_ops cfs_hash_nr_bkt_spin_lops = {
.hs_lock = cfs_hash_nl_lock,
.hs_unlock = cfs_hash_nl_unlock,
.hs_bkt_lock = cfs_hash_spin_lock,
.hs_bkt_unlock = cfs_hash_spin_unlock,
};
/** rw bucket lock, rehash is disabled */
static struct cfs_hash_lock_ops cfs_hash_nr_bkt_rw_lops = {
.hs_lock = cfs_hash_nl_lock,
.hs_unlock = cfs_hash_nl_unlock,
.hs_bkt_lock = cfs_hash_rw_lock,
.hs_bkt_unlock = cfs_hash_rw_unlock,
};
/** rw_sem bucket lock, rehash is disabled */
static struct cfs_hash_lock_ops cfs_hash_nr_bkt_rw_sem_lops = {
.hs_lock = cfs_hash_nl_lock,
.hs_unlock = cfs_hash_nl_unlock,
.hs_bkt_lock = cfs_hash_rw_sem_lock,
.hs_bkt_unlock = cfs_hash_rw_sem_unlock,
};
/** rw_sem bucket lock, rehash is enabled */
static struct cfs_hash_lock_ops cfs_hash_bkt_rw_sem_lops = {
.hs_lock = cfs_hash_rw_sem_lock,
.hs_unlock = cfs_hash_rw_sem_unlock,
.hs_bkt_lock = cfs_hash_rw_sem_lock,
.hs_bkt_unlock = cfs_hash_rw_sem_unlock,
};
static void
cfs_hash_lock_setup(struct cfs_hash *hs)
{
if (cfs_hash_with_no_lock(hs)) {
hs->hs_lops = &cfs_hash_nl_lops;
} else if (cfs_hash_with_no_bktlock(hs)) {
hs->hs_lops = &cfs_hash_nbl_lops;
spin_lock_init(&hs->hs_lock.spin);
} else if (cfs_hash_with_rehash(hs)) {
if (cfs_hash_with_rw_sem_bktlock(hs)) {
init_rwsem(&hs->hs_lock.rw_sem);
hs->hs_lops = &cfs_hash_bkt_rw_sem_lops;
} else {
rwlock_init(&hs->hs_lock.rw);
if (cfs_hash_with_rw_bktlock(hs))
hs->hs_lops = &cfs_hash_bkt_rw_lops;
else if (cfs_hash_with_spin_bktlock(hs))
hs->hs_lops = &cfs_hash_bkt_spin_lops;
else
LBUG();
}
} else {
if (cfs_hash_with_rw_bktlock(hs))
hs->hs_lops = &cfs_hash_nr_bkt_rw_lops;
else if (cfs_hash_with_spin_bktlock(hs))
hs->hs_lops = &cfs_hash_nr_bkt_spin_lops;
else if (cfs_hash_with_rw_sem_bktlock(hs))
hs->hs_lops = &cfs_hash_nr_bkt_rw_sem_lops;
else
LBUG();
}
}
/**
* Simple hash head without depth tracking
* new element is always added to head of hlist
*/
struct cfs_hash_head {
struct hlist_head hh_head; /**< entries list */
};
static int
cfs_hash_hh_hhead_size(struct cfs_hash *hs)
{
return sizeof(struct cfs_hash_head);
}
static struct hlist_head *
cfs_hash_hh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
{
struct cfs_hash_head *head;
head = (struct cfs_hash_head *)&bd->bd_bucket->hsb_head[0];
return &head[bd->bd_offset].hh_head;
}
static int
cfs_hash_hh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
hlist_add_head(hnode, cfs_hash_hh_hhead(hs, bd));
return -1; /* unknown depth */
}
static int
cfs_hash_hh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
hlist_del_init(hnode);
return -1; /* unknown depth */
}
/**
* Simple hash head with depth tracking
* new element is always added to head of hlist
*/
struct cfs_hash_head_dep {
struct hlist_head hd_head; /**< entries list */
unsigned int hd_depth; /**< list length */
};
static int
cfs_hash_hd_hhead_size(struct cfs_hash *hs)
{
return sizeof(struct cfs_hash_head_dep);
}
static struct hlist_head *
cfs_hash_hd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
{
struct cfs_hash_head_dep *head;
head = (struct cfs_hash_head_dep *)&bd->bd_bucket->hsb_head[0];
return &head[bd->bd_offset].hd_head;
}
static int
cfs_hash_hd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
struct cfs_hash_head_dep *hh;
hh = container_of(cfs_hash_hd_hhead(hs, bd),
struct cfs_hash_head_dep, hd_head);
hlist_add_head(hnode, &hh->hd_head);
return ++hh->hd_depth;
}
static int
cfs_hash_hd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
struct cfs_hash_head_dep *hh;
hh = container_of(cfs_hash_hd_hhead(hs, bd),
struct cfs_hash_head_dep, hd_head);
hlist_del_init(hnode);
return --hh->hd_depth;
}
/**
* double links hash head without depth tracking
* new element is always added to tail of hlist
*/
struct cfs_hash_dhead {
struct hlist_head dh_head; /**< entries list */
struct hlist_node *dh_tail; /**< the last entry */
};
static int
cfs_hash_dh_hhead_size(struct cfs_hash *hs)
{
return sizeof(struct cfs_hash_dhead);
}
static struct hlist_head *
cfs_hash_dh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
{
struct cfs_hash_dhead *head;
head = (struct cfs_hash_dhead *)&bd->bd_bucket->hsb_head[0];
return &head[bd->bd_offset].dh_head;
}
static int
cfs_hash_dh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
struct cfs_hash_dhead *dh;
dh = container_of(cfs_hash_dh_hhead(hs, bd),
struct cfs_hash_dhead, dh_head);
if (dh->dh_tail != NULL) /* not empty */
hlist_add_behind(hnode, dh->dh_tail);
else /* empty list */
hlist_add_head(hnode, &dh->dh_head);
dh->dh_tail = hnode;
return -1; /* unknown depth */
}
static int
cfs_hash_dh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnd)
{
struct cfs_hash_dhead *dh;
dh = container_of(cfs_hash_dh_hhead(hs, bd),
struct cfs_hash_dhead, dh_head);
if (hnd->next == NULL) { /* it's the tail */
dh->dh_tail = (hnd->pprev == &dh->dh_head.first) ? NULL :
container_of(hnd->pprev, struct hlist_node, next);
}
hlist_del_init(hnd);
return -1; /* unknown depth */
}
/**
* double links hash head with depth tracking
* new element is always added to tail of hlist
*/
struct cfs_hash_dhead_dep {
struct hlist_head dd_head; /**< entries list */
struct hlist_node *dd_tail; /**< the last entry */
unsigned int dd_depth; /**< list length */
};
static int
cfs_hash_dd_hhead_size(struct cfs_hash *hs)
{
return sizeof(struct cfs_hash_dhead_dep);
}
static struct hlist_head *
cfs_hash_dd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
{
struct cfs_hash_dhead_dep *head;
head = (struct cfs_hash_dhead_dep *)&bd->bd_bucket->hsb_head[0];
return &head[bd->bd_offset].dd_head;
}
static int
cfs_hash_dd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
struct cfs_hash_dhead_dep *dh;
dh = container_of(cfs_hash_dd_hhead(hs, bd),
struct cfs_hash_dhead_dep, dd_head);
if (dh->dd_tail != NULL) /* not empty */
hlist_add_behind(hnode, dh->dd_tail);
else /* empty list */
hlist_add_head(hnode, &dh->dd_head);
dh->dd_tail = hnode;
return ++dh->dd_depth;
}
static int
cfs_hash_dd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnd)
{
struct cfs_hash_dhead_dep *dh;
dh = container_of(cfs_hash_dd_hhead(hs, bd),
struct cfs_hash_dhead_dep, dd_head);
if (hnd->next == NULL) { /* it's the tail */
dh->dd_tail = (hnd->pprev == &dh->dd_head.first) ? NULL :
container_of(hnd->pprev, struct hlist_node, next);
}
hlist_del_init(hnd);
return --dh->dd_depth;
}
static struct cfs_hash_hlist_ops cfs_hash_hh_hops = {
.hop_hhead = cfs_hash_hh_hhead,
.hop_hhead_size = cfs_hash_hh_hhead_size,
.hop_hnode_add = cfs_hash_hh_hnode_add,
.hop_hnode_del = cfs_hash_hh_hnode_del,
};
static struct cfs_hash_hlist_ops cfs_hash_hd_hops = {
.hop_hhead = cfs_hash_hd_hhead,
.hop_hhead_size = cfs_hash_hd_hhead_size,
.hop_hnode_add = cfs_hash_hd_hnode_add,
.hop_hnode_del = cfs_hash_hd_hnode_del,
};
static struct cfs_hash_hlist_ops cfs_hash_dh_hops = {
.hop_hhead = cfs_hash_dh_hhead,
.hop_hhead_size = cfs_hash_dh_hhead_size,
.hop_hnode_add = cfs_hash_dh_hnode_add,
.hop_hnode_del = cfs_hash_dh_hnode_del,
};
static struct cfs_hash_hlist_ops cfs_hash_dd_hops = {
.hop_hhead = cfs_hash_dd_hhead,
.hop_hhead_size = cfs_hash_dd_hhead_size,
.hop_hnode_add = cfs_hash_dd_hnode_add,
.hop_hnode_del = cfs_hash_dd_hnode_del,
};
static void
cfs_hash_hlist_setup(struct cfs_hash *hs)
{
if (cfs_hash_with_add_tail(hs)) {
hs->hs_hops = cfs_hash_with_depth(hs) ?
&cfs_hash_dd_hops : &cfs_hash_dh_hops;
} else {
hs->hs_hops = cfs_hash_with_depth(hs) ?
&cfs_hash_hd_hops : &cfs_hash_hh_hops;
}
}
static void
cfs_hash_bd_from_key(struct cfs_hash *hs, struct cfs_hash_bucket **bkts,
unsigned int bits, const void *key, struct cfs_hash_bd *bd)
{
unsigned int index = cfs_hash_id(hs, key, bits);
LASSERT(bits == hs->hs_cur_bits || bits == hs->hs_rehash_bits);
bd->bd_bucket = bkts[index & ((1U << (bits - hs->hs_bkt_bits)) - 1)];
bd->bd_offset = index >> (bits - hs->hs_bkt_bits);
}
void
cfs_hash_bd_get(struct cfs_hash *hs, const void *key, struct cfs_hash_bd *bd)
{
/* NB: caller should hold hs->hs_rwlock if REHASH is set */
if (likely(hs->hs_rehash_buckets == NULL)) {
cfs_hash_bd_from_key(hs, hs->hs_buckets,
hs->hs_cur_bits, key, bd);
} else {
LASSERT(hs->hs_rehash_bits != 0);
cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
hs->hs_rehash_bits, key, bd);
}
}
EXPORT_SYMBOL(cfs_hash_bd_get);
static inline void
cfs_hash_bd_dep_record(struct cfs_hash *hs, struct cfs_hash_bd *bd, int dep_cur)
{
if (likely(dep_cur <= bd->bd_bucket->hsb_depmax))
return;
bd->bd_bucket->hsb_depmax = dep_cur;
# if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
if (likely(warn_on_depth == 0 ||
max(warn_on_depth, hs->hs_dep_max) >= dep_cur))
return;
spin_lock(&hs->hs_dep_lock);
hs->hs_dep_max = dep_cur;
hs->hs_dep_bkt = bd->bd_bucket->hsb_index;
hs->hs_dep_off = bd->bd_offset;
hs->hs_dep_bits = hs->hs_cur_bits;
spin_unlock(&hs->hs_dep_lock);
queue_work(cfs_rehash_wq, &hs->hs_dep_work);
# endif
}
void
cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
int rc;
rc = hs->hs_hops->hop_hnode_add(hs, bd, hnode);
cfs_hash_bd_dep_record(hs, bd, rc);
bd->bd_bucket->hsb_version++;
if (unlikely(bd->bd_bucket->hsb_version == 0))
bd->bd_bucket->hsb_version++;
bd->bd_bucket->hsb_count++;
if (cfs_hash_with_counter(hs))
atomic_inc(&hs->hs_count);
if (!cfs_hash_with_no_itemref(hs))
cfs_hash_get(hs, hnode);
}
EXPORT_SYMBOL(cfs_hash_bd_add_locked);
void
cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode)
{
hs->hs_hops->hop_hnode_del(hs, bd, hnode);
LASSERT(bd->bd_bucket->hsb_count > 0);
bd->bd_bucket->hsb_count--;
bd->bd_bucket->hsb_version++;
if (unlikely(bd->bd_bucket->hsb_version == 0))
bd->bd_bucket->hsb_version++;
if (cfs_hash_with_counter(hs)) {
LASSERT(atomic_read(&hs->hs_count) > 0);
atomic_dec(&hs->hs_count);
}
if (!cfs_hash_with_no_itemref(hs))
cfs_hash_put_locked(hs, hnode);
}
EXPORT_SYMBOL(cfs_hash_bd_del_locked);
void
cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
struct cfs_hash_bd *bd_new, struct hlist_node *hnode)
{
struct cfs_hash_bucket *obkt = bd_old->bd_bucket;
struct cfs_hash_bucket *nbkt = bd_new->bd_bucket;
int rc;
if (cfs_hash_bd_compare(bd_old, bd_new) == 0)
return;
/* use cfs_hash_bd_hnode_add/del, to avoid atomic & refcount ops
* in cfs_hash_bd_del/add_locked */
hs->hs_hops->hop_hnode_del(hs, bd_old, hnode);
rc = hs->hs_hops->hop_hnode_add(hs, bd_new, hnode);
cfs_hash_bd_dep_record(hs, bd_new, rc);
LASSERT(obkt->hsb_count > 0);
obkt->hsb_count--;
obkt->hsb_version++;
if (unlikely(obkt->hsb_version == 0))
obkt->hsb_version++;
nbkt->hsb_count++;
nbkt->hsb_version++;
if (unlikely(nbkt->hsb_version == 0))
nbkt->hsb_version++;
}
enum {
/** always set, for sanity (avoid ZERO intent) */
CFS_HS_LOOKUP_MASK_FIND = BIT(0),
/** return entry with a ref */
CFS_HS_LOOKUP_MASK_REF = BIT(1),
/** add entry if not existing */
CFS_HS_LOOKUP_MASK_ADD = BIT(2),
/** delete entry, ignore other masks */
CFS_HS_LOOKUP_MASK_DEL = BIT(3),
};
enum cfs_hash_lookup_intent {
/** return item w/o refcount */
CFS_HS_LOOKUP_IT_PEEK = CFS_HS_LOOKUP_MASK_FIND,
/** return item with refcount */
CFS_HS_LOOKUP_IT_FIND = (CFS_HS_LOOKUP_MASK_FIND |
CFS_HS_LOOKUP_MASK_REF),
/** return item w/o refcount if existed, otherwise add */
CFS_HS_LOOKUP_IT_ADD = (CFS_HS_LOOKUP_MASK_FIND |
CFS_HS_LOOKUP_MASK_ADD),
/** return item with refcount if existed, otherwise add */
CFS_HS_LOOKUP_IT_FINDADD = (CFS_HS_LOOKUP_IT_FIND |
CFS_HS_LOOKUP_MASK_ADD),
/** delete if existed */
CFS_HS_LOOKUP_IT_FINDDEL = (CFS_HS_LOOKUP_MASK_FIND |
CFS_HS_LOOKUP_MASK_DEL)
};
static struct hlist_node *
cfs_hash_bd_lookup_intent(struct cfs_hash *hs, struct cfs_hash_bd *bd,
const void *key, struct hlist_node *hnode,
enum cfs_hash_lookup_intent intent)
{
struct hlist_head *hhead = cfs_hash_bd_hhead(hs, bd);
struct hlist_node *ehnode;
struct hlist_node *match;
int intent_add = (intent & CFS_HS_LOOKUP_MASK_ADD) != 0;
/* with this function, we can avoid a lot of useless refcount ops,
* which are expensive atomic operations most time. */
match = intent_add ? NULL : hnode;
hlist_for_each(ehnode, hhead) {
if (!cfs_hash_keycmp(hs, key, ehnode))
continue;
if (match != NULL && match != ehnode) /* can't match */
continue;
/* match and ... */
if ((intent & CFS_HS_LOOKUP_MASK_DEL) != 0) {
cfs_hash_bd_del_locked(hs, bd, ehnode);
return ehnode;
}
/* caller wants refcount? */
if ((intent & CFS_HS_LOOKUP_MASK_REF) != 0)
cfs_hash_get(hs, ehnode);
return ehnode;
}
/* no match item */
if (!intent_add)
return NULL;
LASSERT(hnode != NULL);
cfs_hash_bd_add_locked(hs, bd, hnode);
return hnode;
}
struct hlist_node *
cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
const void *key)
{
return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
CFS_HS_LOOKUP_IT_FIND);
}
EXPORT_SYMBOL(cfs_hash_bd_lookup_locked);
struct hlist_node *
cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
const void *key)
{
return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
CFS_HS_LOOKUP_IT_PEEK);
}
EXPORT_SYMBOL(cfs_hash_bd_peek_locked);
static void
cfs_hash_multi_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
unsigned n, int excl)
{
struct cfs_hash_bucket *prev = NULL;
int i;
/**
* bds must be ascendantly ordered by bd->bd_bucket->hsb_index.
* NB: it's possible that several bds point to the same bucket but
* have different bd::bd_offset, so need take care of deadlock.
*/
cfs_hash_for_each_bd(bds, n, i) {
if (prev == bds[i].bd_bucket)
continue;
LASSERT(prev == NULL ||
prev->hsb_index < bds[i].bd_bucket->hsb_index);
cfs_hash_bd_lock(hs, &bds[i], excl);
prev = bds[i].bd_bucket;
}
}
static void
cfs_hash_multi_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
unsigned n, int excl)
{
struct cfs_hash_bucket *prev = NULL;
int i;
cfs_hash_for_each_bd(bds, n, i) {
if (prev != bds[i].bd_bucket) {
cfs_hash_bd_unlock(hs, &bds[i], excl);
prev = bds[i].bd_bucket;
}
}
}
static struct hlist_node *
cfs_hash_multi_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
unsigned n, const void *key)
{
struct hlist_node *ehnode;
unsigned i;
cfs_hash_for_each_bd(bds, n, i) {
ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, NULL,
CFS_HS_LOOKUP_IT_FIND);
if (ehnode != NULL)
return ehnode;
}
return NULL;
}
static struct hlist_node *
cfs_hash_multi_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
unsigned n, const void *key,
struct hlist_node *hnode, int noref)
{
struct hlist_node *ehnode;
int intent;
unsigned i;
LASSERT(hnode != NULL);
intent = CFS_HS_LOOKUP_IT_PEEK | (!noref * CFS_HS_LOOKUP_MASK_REF);
cfs_hash_for_each_bd(bds, n, i) {
ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key,
NULL, intent);
if (ehnode != NULL)
return ehnode;
}
if (i == 1) { /* only one bucket */
cfs_hash_bd_add_locked(hs, &bds[0], hnode);
} else {
struct cfs_hash_bd mybd;
cfs_hash_bd_get(hs, key, &mybd);
cfs_hash_bd_add_locked(hs, &mybd, hnode);
}
return hnode;
}
static struct hlist_node *
cfs_hash_multi_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
unsigned n, const void *key,
struct hlist_node *hnode)
{
struct hlist_node *ehnode;
unsigned i;
cfs_hash_for_each_bd(bds, n, i) {
ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, hnode,
CFS_HS_LOOKUP_IT_FINDDEL);
if (ehnode != NULL)
return ehnode;
}
return NULL;
}
static void
cfs_hash_bd_order(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
{
int rc;
if (bd2->bd_bucket == NULL)
return;
if (bd1->bd_bucket == NULL) {
*bd1 = *bd2;
bd2->bd_bucket = NULL;
return;
}
rc = cfs_hash_bd_compare(bd1, bd2);
if (rc == 0) {
bd2->bd_bucket = NULL;
} else if (rc > 0) {
swap(*bd1, *bd2); /* swab bd1 and bd2 */
}
}
void
cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
struct cfs_hash_bd *bds)
{
/* NB: caller should hold hs_lock.rw if REHASH is set */
cfs_hash_bd_from_key(hs, hs->hs_buckets,
hs->hs_cur_bits, key, &bds[0]);
if (likely(hs->hs_rehash_buckets == NULL)) {
/* no rehash or not rehashing */
bds[1].bd_bucket = NULL;
return;
}
LASSERT(hs->hs_rehash_bits != 0);
cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
hs->hs_rehash_bits, key, &bds[1]);
cfs_hash_bd_order(&bds[0], &bds[1]);
}
void
cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
{
cfs_hash_multi_bd_lock(hs, bds, 2, excl);
}
void
cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
{
cfs_hash_multi_bd_unlock(hs, bds, 2, excl);
}
struct hlist_node *
cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
const void *key)
{
return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key);
}
struct hlist_node *
cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
const void *key, struct hlist_node *hnode,
int noref)
{
return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key,
hnode, noref);
}
struct hlist_node *
cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
const void *key, struct hlist_node *hnode)
{
return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode);
}
static void
cfs_hash_buckets_free(struct cfs_hash_bucket **buckets,
int bkt_size, int prev_size, int size)
{
int i;
for (i = prev_size; i < size; i++)
LIBCFS_FREE(buckets[i], bkt_size);
LIBCFS_FREE(buckets, sizeof(buckets[0]) * size);
}
/*
* Create or grow bucket memory. Return old_buckets if no allocation was
* needed, the newly allocated buckets if allocation was needed and
* successful, and NULL on error.
*/
static struct cfs_hash_bucket **
cfs_hash_buckets_realloc(struct cfs_hash *hs, struct cfs_hash_bucket **old_bkts,
unsigned int old_size, unsigned int new_size)
{
struct cfs_hash_bucket **new_bkts;
int i;
LASSERT(old_size == 0 || old_bkts != NULL);
if (old_bkts != NULL && old_size == new_size)
return old_bkts;
LIBCFS_ALLOC(new_bkts, sizeof(new_bkts[0]) * new_size);
if (new_bkts == NULL)
return NULL;
if (old_bkts != NULL) {
memcpy(new_bkts, old_bkts,
min(old_size, new_size) * sizeof(*old_bkts));
}
for (i = old_size; i < new_size; i++) {
struct hlist_head *hhead;
struct cfs_hash_bd bd;
LIBCFS_ALLOC(new_bkts[i], cfs_hash_bkt_size(hs));
if (new_bkts[i] == NULL) {
cfs_hash_buckets_free(new_bkts, cfs_hash_bkt_size(hs),
old_size, new_size);
return NULL;
}
new_bkts[i]->hsb_index = i;
new_bkts[i]->hsb_version = 1; /* shouldn't be zero */
new_bkts[i]->hsb_depmax = -1; /* unknown */
bd.bd_bucket = new_bkts[i];
cfs_hash_bd_for_each_hlist(hs, &bd, hhead)
INIT_HLIST_HEAD(hhead);
if (cfs_hash_with_no_lock(hs) ||
cfs_hash_with_no_bktlock(hs))
continue;
if (cfs_hash_with_rw_bktlock(hs))
rwlock_init(&new_bkts[i]->hsb_lock.rw);
else if (cfs_hash_with_spin_bktlock(hs))
spin_lock_init(&new_bkts[i]->hsb_lock.spin);
else if (cfs_hash_with_rw_sem_bktlock(hs))
init_rwsem(&new_bkts[i]->hsb_lock.rw_sem);
else
LBUG(); /* invalid use-case */
}
return new_bkts;
}
/**
* Initialize new libcfs hash, where:
* @name - Descriptive hash name
* @cur_bits - Initial hash table size, in bits
* @max_bits - Maximum allowed hash table resize, in bits
* @ops - Registered hash table operations
* @flags - CFS_HASH_REHASH enable synamic hash resizing
* - CFS_HASH_SORT enable chained hash sort
*/
static void cfs_hash_rehash_worker(struct work_struct *work);
#if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
static void cfs_hash_dep_print(struct work_struct *work)
{
struct cfs_hash *hs = container_of(work, struct cfs_hash, hs_dep_work);
int dep;
int bkt;
int off;
int bits;
spin_lock(&hs->hs_dep_lock);
dep = hs->hs_dep_max;
bkt = hs->hs_dep_bkt;
off = hs->hs_dep_off;
bits = hs->hs_dep_bits;
spin_unlock(&hs->hs_dep_lock);
LCONSOLE_WARN("#### HASH %s (bits: %d): max depth %d at bucket %d/%d\n",
hs->hs_name, bits, dep, bkt, off);
spin_lock(&hs->hs_dep_lock);
hs->hs_dep_bits = 0; /* mark as workitem done */
spin_unlock(&hs->hs_dep_lock);
return 0;
}
static void cfs_hash_depth_wi_init(struct cfs_hash *hs)
{
spin_lock_init(&hs->hs_dep_lock);
INIT_WORK(&hs->hs_dep_work, cfs_hash_dep_print);
}
static void cfs_hash_depth_wi_cancel(struct cfs_hash *hs)
{
cancel_work_sync(&hs->hs_dep_work);
}
#else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
static inline void cfs_hash_depth_wi_init(struct cfs_hash *hs) {}
static inline void cfs_hash_depth_wi_cancel(struct cfs_hash *hs) {}
#endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */
struct cfs_hash *
cfs_hash_create(const char *name, unsigned cur_bits, unsigned max_bits,
unsigned bkt_bits, unsigned extra_bytes,
unsigned min_theta, unsigned max_theta,
struct cfs_hash_ops *ops, unsigned flags)
{
struct cfs_hash *hs;
int len;
ENTRY;
BUILD_BUG_ON(CFS_HASH_THETA_BITS >= 15);
LASSERT(name != NULL);
LASSERT(ops != NULL);
LASSERT(ops->hs_key);
LASSERT(ops->hs_hash);
LASSERT(ops->hs_object);
LASSERT(ops->hs_keycmp);
LASSERT(ops->hs_get != NULL);
LASSERT(ops->hs_put != NULL || ops->hs_put_locked != NULL);
if ((flags & CFS_HASH_REHASH) != 0)
flags |= CFS_HASH_COUNTER; /* must have counter */
LASSERT(cur_bits > 0);
LASSERT(cur_bits >= bkt_bits);
LASSERT(max_bits >= cur_bits && max_bits < 31);
LASSERT(ergo((flags & CFS_HASH_REHASH) == 0, cur_bits == max_bits));
LASSERT(ergo((flags & CFS_HASH_REHASH) != 0,
(flags & CFS_HASH_NO_LOCK) == 0));
LASSERT(ergo((flags & CFS_HASH_REHASH_KEY) != 0,
ops->hs_keycpy != NULL));
len = (flags & CFS_HASH_BIGNAME) == 0 ?
CFS_HASH_NAME_LEN : CFS_HASH_BIGNAME_LEN;
LIBCFS_ALLOC(hs, sizeof(struct cfs_hash) + len);
if (hs == NULL)
RETURN(NULL);
strscpy(hs->hs_name, name, len);
hs->hs_flags = flags;
kref_init(&hs->hs_refcount);
atomic_set(&hs->hs_count, 0);
cfs_hash_lock_setup(hs);
cfs_hash_hlist_setup(hs);
hs->hs_cur_bits = (__u8)cur_bits;
hs->hs_min_bits = (__u8)cur_bits;
hs->hs_max_bits = (__u8)max_bits;
hs->hs_bkt_bits = (__u8)bkt_bits;
hs->hs_ops = ops;
hs->hs_extra_bytes = extra_bytes;
hs->hs_rehash_bits = 0;
INIT_WORK(&hs->hs_rehash_work, cfs_hash_rehash_worker);
cfs_hash_depth_wi_init(hs);
if (cfs_hash_with_rehash(hs))
__cfs_hash_set_theta(hs, min_theta, max_theta);
hs->hs_buckets = cfs_hash_buckets_realloc(hs, NULL, 0,
CFS_HASH_NBKT(hs));
if (hs->hs_buckets != NULL)
return hs;
LIBCFS_FREE(hs, sizeof(struct cfs_hash) + len);
RETURN(NULL);
}
EXPORT_SYMBOL(cfs_hash_create);
/**
* Cleanup libcfs hash @hs.
*/
static void
cfs_hash_destroy(struct kref *kref)
{
struct cfs_hash *hs = container_of(kref, struct cfs_hash, hs_refcount);
struct hlist_node *hnode;
struct hlist_node *pos;
struct cfs_hash_bd bd;
int i;
ENTRY;
LASSERT(hs != NULL);
LASSERT(!cfs_hash_is_exiting(hs) &&
!cfs_hash_is_iterating(hs));
/**
* prohibit further rehashes, don't need any lock because
* I'm the only (last) one can change it.
*/
hs->hs_exiting = 1;
if (cfs_hash_with_rehash(hs))
cfs_hash_rehash_cancel(hs);
cfs_hash_depth_wi_cancel(hs);
/* rehash should be done/canceled */
LASSERT(hs->hs_buckets != NULL &&
hs->hs_rehash_buckets == NULL);
cfs_hash_for_each_bucket(hs, &bd, i) {
struct hlist_head *hhead;
LASSERT(bd.bd_bucket != NULL);
/* no need to take this lock, just for consistent code */
cfs_hash_bd_lock(hs, &bd, 1);
cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
hlist_for_each_safe(hnode, pos, hhead) {
LASSERTF(!cfs_hash_with_assert_empty(hs),
"hash %s bucket %u(%u) is not "
" empty: %u items left\n",
hs->hs_name, bd.bd_bucket->hsb_index,
bd.bd_offset, bd.bd_bucket->hsb_count);
/* can't assert key valicate, because we
* can interrupt rehash */
cfs_hash_bd_del_locked(hs, &bd, hnode);
cfs_hash_exit(hs, hnode);
}
}
LASSERT(bd.bd_bucket->hsb_count == 0);
cfs_hash_bd_unlock(hs, &bd, 1);
cond_resched();
}
LASSERT(atomic_read(&hs->hs_count) == 0);
cfs_hash_buckets_free(hs->hs_buckets, cfs_hash_bkt_size(hs),
0, CFS_HASH_NBKT(hs));
i = cfs_hash_with_bigname(hs) ?
CFS_HASH_BIGNAME_LEN : CFS_HASH_NAME_LEN;
LIBCFS_FREE(hs, sizeof(struct cfs_hash) + i);
EXIT;
}
struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs)
{
if (kref_get_unless_zero(&hs->hs_refcount))
return hs;
return NULL;
}
EXPORT_SYMBOL(cfs_hash_getref);
void cfs_hash_putref(struct cfs_hash *hs)
{
kref_put(&hs->hs_refcount, cfs_hash_destroy);
}
EXPORT_SYMBOL(cfs_hash_putref);
static inline int
cfs_hash_rehash_bits(struct cfs_hash *hs)
{
if (cfs_hash_with_no_lock(hs) ||
!cfs_hash_with_rehash(hs))
return -EOPNOTSUPP;
if (unlikely(cfs_hash_is_exiting(hs)))
return -ESRCH;
if (unlikely(cfs_hash_is_rehashing(hs)))
return -EALREADY;
if (unlikely(cfs_hash_is_iterating(hs)))
return -EAGAIN;
/* XXX: need to handle case with max_theta != 2.0
* and the case with min_theta != 0.5 */
if ((hs->hs_cur_bits < hs->hs_max_bits) &&
(__cfs_hash_theta(hs) > hs->hs_max_theta))
return hs->hs_cur_bits + 1;
if (!cfs_hash_with_shrink(hs))
return 0;
if ((hs->hs_cur_bits > hs->hs_min_bits) &&
(__cfs_hash_theta(hs) < hs->hs_min_theta))
return hs->hs_cur_bits - 1;
return 0;
}
/**
* don't allow inline rehash if:
* - user wants non-blocking change (add/del) on hash table
* - too many elements
*/
static inline int
cfs_hash_rehash_inline(struct cfs_hash *hs)
{
return !cfs_hash_with_nblk_change(hs) &&
atomic_read(&hs->hs_count) < CFS_HASH_LOOP_HOG;
}
/**
* Add item @hnode to libcfs hash @hs using @key. The registered
* ops->hs_get function will be called when the item is added.
*/
void
cfs_hash_add(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
{
struct cfs_hash_bd bd;
int bits;
LASSERT(hlist_unhashed(hnode));
cfs_hash_lock(hs, 0);
cfs_hash_bd_get_and_lock(hs, key, &bd, 1);
cfs_hash_key_validate(hs, key, hnode);
cfs_hash_bd_add_locked(hs, &bd, hnode);
cfs_hash_bd_unlock(hs, &bd, 1);
bits = cfs_hash_rehash_bits(hs);
cfs_hash_unlock(hs, 0);
if (bits > 0)
cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
}
EXPORT_SYMBOL(cfs_hash_add);
static struct hlist_node *
cfs_hash_find_or_add(struct cfs_hash *hs, const void *key,
struct hlist_node *hnode, int noref)
{
struct hlist_node *ehnode;
struct cfs_hash_bd bds[2];
int bits = 0;
LASSERTF(hlist_unhashed(hnode), "hnode = %px\n", hnode);
cfs_hash_lock(hs, 0);
cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
cfs_hash_key_validate(hs, key, hnode);
ehnode = cfs_hash_dual_bd_findadd_locked(hs, bds, key,
hnode, noref);
cfs_hash_dual_bd_unlock(hs, bds, 1);
if (ehnode == hnode) /* new item added */
bits = cfs_hash_rehash_bits(hs);
cfs_hash_unlock(hs, 0);
if (bits > 0)
cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
return ehnode;
}
/**
* Add item @hnode to libcfs hash @hs using @key. The registered
* ops->hs_get function will be called if the item was added.
* Returns 0 on success or -EALREADY on key collisions.
*/
int
cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
struct hlist_node *hnode)
{
return cfs_hash_find_or_add(hs, key, hnode, 1) != hnode ?
-EALREADY : 0;
}
EXPORT_SYMBOL(cfs_hash_add_unique);
/**
* Add item @hnode to libcfs hash @hs using @key. If this @key
* already exists in the hash then ops->hs_get will be called on the
* conflicting entry and that entry will be returned to the caller.
* Otherwise ops->hs_get is called on the item which was added.
*/
void *
cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
struct hlist_node *hnode)
{
hnode = cfs_hash_find_or_add(hs, key, hnode, 0);
return cfs_hash_object(hs, hnode);
}
EXPORT_SYMBOL(cfs_hash_findadd_unique);
/**
* Delete item @hnode from the libcfs hash @hs using @key. The @key
* is required to ensure the correct hash bucket is locked since there
* is no direct linkage from the item to the bucket. The object
* removed from the hash will be returned and obs->hs_put is called
* on the removed object.
*/
void *
cfs_hash_del(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
{
void *obj = NULL;
int bits = 0;
struct cfs_hash_bd bds[2];
cfs_hash_lock(hs, 0);
cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
/* NB: do nothing if @hnode is not in hash table */
if (hnode == NULL || !hlist_unhashed(hnode)) {
if (bds[1].bd_bucket == NULL && hnode != NULL) {
cfs_hash_bd_del_locked(hs, &bds[0], hnode);
} else {
hnode = cfs_hash_dual_bd_finddel_locked(hs, bds,
key, hnode);
}
}
if (hnode != NULL) {
obj = cfs_hash_object(hs, hnode);
bits = cfs_hash_rehash_bits(hs);
}
cfs_hash_dual_bd_unlock(hs, bds, 1);
cfs_hash_unlock(hs, 0);
if (bits > 0)
cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
return obj;
}
EXPORT_SYMBOL(cfs_hash_del);
/**
* Delete item given @key in libcfs hash @hs. The first @key found in
* the hash will be removed, if the key exists multiple times in the hash
* @hs this function must be called once per key. The removed object
* will be returned and ops->hs_put is called on the removed object.
*/
void *
cfs_hash_del_key(struct cfs_hash *hs, const void *key)
{
return cfs_hash_del(hs, key, NULL);
}
EXPORT_SYMBOL(cfs_hash_del_key);
/**
* Lookup an item using @key in the libcfs hash @hs and return it.
* If the @key is found in the hash hs->hs_get() is called and the
* matching objects is returned. It is the callers responsibility
* to call the counterpart ops->hs_put using the cfs_hash_put() macro
* when when finished with the object. If the @key was not found
* in the hash @hs NULL is returned.
*/
void *
cfs_hash_lookup(struct cfs_hash *hs, const void *key)
{
void *obj = NULL;
struct hlist_node *hnode;
struct cfs_hash_bd bds[2];
cfs_hash_lock(hs, 0);
cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
hnode = cfs_hash_dual_bd_lookup_locked(hs, bds, key);
if (hnode != NULL)
obj = cfs_hash_object(hs, hnode);
cfs_hash_dual_bd_unlock(hs, bds, 0);
cfs_hash_unlock(hs, 0);
return obj;
}
EXPORT_SYMBOL(cfs_hash_lookup);
static void
cfs_hash_for_each_enter(struct cfs_hash *hs)
{
LASSERT(!cfs_hash_is_exiting(hs));
if (!cfs_hash_with_rehash(hs))
return;
/*
* NB: it's race on cfs_has_t::hs_iterating, but doesn't matter
* because it's just an unreliable signal to rehash-thread,
* rehash-thread will try to finish rehash ASAP when seeing this.
*/
hs->hs_iterating = 1;
cfs_hash_lock(hs, 1);
hs->hs_iterators++;
cfs_hash_unlock(hs, 1);
/* NB: iteration is mostly called by service thread,
* we tend to cancel pending rehash-request, instead of
* blocking service thread, we will relaunch rehash request
* after iteration
*/
if (cfs_hash_is_rehashing(hs))
cfs_hash_rehash_cancel(hs);
}
static void
cfs_hash_for_each_exit(struct cfs_hash *hs)
{
int remained;
int bits;
if (!cfs_hash_with_rehash(hs))
return;
cfs_hash_lock(hs, 1);
remained = --hs->hs_iterators;
bits = cfs_hash_rehash_bits(hs);
cfs_hash_unlock(hs, 1);
/* NB: it's race on cfs_has_t::hs_iterating, see above */
if (remained == 0)
hs->hs_iterating = 0;
if (bits > 0) {
cfs_hash_rehash(hs, atomic_read(&hs->hs_count) <
CFS_HASH_LOOP_HOG);
}
}
/**
* For each item in the libcfs hash @hs call the passed callback @func
* and pass to it as an argument each hash item and the private @data.
*
* a) the function may sleep!
* b) during the callback:
* . the bucket lock is held so the callback must never sleep.
* . if @removal_safe is true, use can remove current item by
* cfs_hash_bd_del_locked
*/
static __u64
cfs_hash_for_each_tight(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
void *data, int remove_safe)
{
struct hlist_node *hnode;
struct hlist_node *pos;
struct cfs_hash_bd bd;
__u64 count = 0;
int excl = !!remove_safe;
int loop = 0;
int i;
ENTRY;
cfs_hash_for_each_enter(hs);
cfs_hash_lock(hs, 0);
LASSERT(!cfs_hash_is_rehashing(hs));
cfs_hash_for_each_bucket(hs, &bd, i) {
struct hlist_head *hhead;
cfs_hash_bd_lock(hs, &bd, excl);
if (func == NULL) { /* only glimpse size */
count += bd.bd_bucket->hsb_count;
cfs_hash_bd_unlock(hs, &bd, excl);
continue;
}
cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
hlist_for_each_safe(hnode, pos, hhead) {
cfs_hash_bucket_validate(hs, &bd, hnode);
count++;
loop++;
if (func(hs, &bd, hnode, data)) {
cfs_hash_bd_unlock(hs, &bd, excl);
goto out;
}
}
}
cfs_hash_bd_unlock(hs, &bd, excl);
if (loop < CFS_HASH_LOOP_HOG)
continue;
loop = 0;
cfs_hash_unlock(hs, 0);
cond_resched();
cfs_hash_lock(hs, 0);
}
out:
cfs_hash_unlock(hs, 0);
cfs_hash_for_each_exit(hs);
RETURN(count);
}
struct cfs_hash_cond_arg {
cfs_hash_cond_opt_cb_t func;
void *arg;
};
static int
cfs_hash_cond_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode, void *data)
{
struct cfs_hash_cond_arg *cond = data;
if (cond->func(cfs_hash_object(hs, hnode), cond->arg))
cfs_hash_bd_del_locked(hs, bd, hnode);
return 0;
}
/**
* Delete item from the libcfs hash @hs when @func return true.
* The write lock being hold during loop for each bucket to avoid
* any object be reference.
*/
void
cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t func, void *data)
{
struct cfs_hash_cond_arg arg = {
.func = func,
.arg = data,
};
cfs_hash_for_each_tight(hs, cfs_hash_cond_del_locked, &arg, 1);
}
EXPORT_SYMBOL(cfs_hash_cond_del);
void
cfs_hash_for_each(struct cfs_hash *hs,
cfs_hash_for_each_cb_t func, void *data)
{
cfs_hash_for_each_tight(hs, func, data, 0);
}
EXPORT_SYMBOL(cfs_hash_for_each);
void
cfs_hash_for_each_safe(struct cfs_hash *hs,
cfs_hash_for_each_cb_t func, void *data)
{
cfs_hash_for_each_tight(hs, func, data, 1);
}
EXPORT_SYMBOL(cfs_hash_for_each_safe);
static int
cfs_hash_peek(struct cfs_hash *hs, struct cfs_hash_bd *bd,
struct hlist_node *hnode, void *data)
{
*(int *)data = 0;
return 1; /* return 1 to break the loop */
}
int
cfs_hash_is_empty(struct cfs_hash *hs)
{
int empty = 1;
cfs_hash_for_each_tight(hs, cfs_hash_peek, &empty, 0);
return empty;
}
EXPORT_SYMBOL(cfs_hash_is_empty);
__u64
cfs_hash_size_get(struct cfs_hash *hs)
{
return cfs_hash_with_counter(hs) ?
atomic_read(&hs->hs_count) :
cfs_hash_for_each_tight(hs, NULL, NULL, 0);
}
EXPORT_SYMBOL(cfs_hash_size_get);
/*
* cfs_hash_for_each_relax:
* Iterate the hash table and call @func on each item without
* any lock. This function can't guarantee to finish iteration
* if these features are enabled:
*
* a. if rehash_key is enabled, an item can be moved from
* one bucket to another bucket
* b. user can remove non-zero-ref item from hash-table,
* so the item can be removed from hash-table, even worse,
* it's possible that user changed key and insert to another
* hash bucket.
* there's no way for us to finish iteration correctly on previous
* two cases, so iteration has to be stopped on change.
*/
static int
cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
void *data, int *pstart)
{
struct hlist_node *hnode;
struct hlist_node *next = NULL;
struct cfs_hash_bd bd;
__u32 version;
int count = 0;
int stop_on_change;
int has_put_locked;
int rc = 0;
int i, end = -1;
ENTRY;
stop_on_change = cfs_hash_with_rehash_key(hs) ||
!cfs_hash_with_no_itemref(hs);
has_put_locked = hs->hs_ops->hs_put_locked != NULL;
cfs_hash_lock(hs, 0);
again:
LASSERT(!cfs_hash_is_rehashing(hs));
cfs_hash_for_each_bucket(hs, &bd, i) {
struct hlist_head *hhead;
if (pstart && i < *pstart)
continue;
else if (end > 0 && i >= end)
break;
cfs_hash_bd_lock(hs, &bd, 0);
version = cfs_hash_bd_version_get(&bd);
cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
hnode = hhead->first;
if (hnode == NULL)
continue;
cfs_hash_get(hs, hnode);
for (; hnode != NULL; hnode = next) {
cfs_hash_bucket_validate(hs, &bd, hnode);
next = hnode->next;
if (next != NULL)
cfs_hash_get(hs, next);
cfs_hash_bd_unlock(hs, &bd, 0);
cfs_hash_unlock(hs, 0);
rc = func(hs, &bd, hnode, data);
if (stop_on_change || !has_put_locked)
cfs_hash_put(hs, hnode);
cond_resched();
count++;
cfs_hash_lock(hs, 0);
cfs_hash_bd_lock(hs, &bd, 0);
if (stop_on_change) {
if (version !=
cfs_hash_bd_version_get(&bd))
rc = -EINTR;
} else if (has_put_locked) {
cfs_hash_put_locked(hs, hnode);
}
if (rc) /* callback wants to break iteration */
break;
}
if (next != NULL) {
if (has_put_locked) {
cfs_hash_put_locked(hs, next);
next = NULL;
}
break;
} else if (rc != 0) {
break;
}
}
cfs_hash_bd_unlock(hs, &bd, 0);
if (next != NULL && !has_put_locked) {
cfs_hash_put(hs, next);
next = NULL;
}
if (rc) /* callback wants to break iteration */
break;
}
if (pstart && *pstart > 0 && rc == 0) {
end = *pstart;
*pstart = 0;
goto again;
}
cfs_hash_unlock(hs, 0);
if (pstart)
*pstart = i;
return count;
}
int
cfs_hash_for_each_nolock(struct cfs_hash *hs,
cfs_hash_for_each_cb_t func, void *data, int start)
{
ENTRY;
if (cfs_hash_with_no_lock(hs) ||
cfs_hash_with_rehash_key(hs) ||
!cfs_hash_with_no_itemref(hs))
RETURN(-EOPNOTSUPP);
if (hs->hs_ops->hs_get == NULL ||
(hs->hs_ops->hs_put == NULL &&
hs->hs_ops->hs_put_locked == NULL))
RETURN(-EOPNOTSUPP);
cfs_hash_for_each_enter(hs);
cfs_hash_for_each_relax(hs, func, data, &start);
cfs_hash_for_each_exit(hs);
RETURN(0);
}
EXPORT_SYMBOL(cfs_hash_for_each_nolock);
/**
* For each hash bucket in the libcfs hash @hs call the passed callback
* @func until all the hash buckets are empty. The passed callback @func
* or the previously registered callback hs->hs_put must remove the item
* from the hash. You may either use the cfs_hash_del() or hlist_del()
* functions. No rwlocks will be held during the callback @func it is
* safe to sleep if needed. This function will not terminate until the
* hash is empty. Note it is still possible to concurrently add new
* items in to the hash. It is the callers responsibility to ensure
* the required locking is in place to prevent concurrent insertions.
*/
int
cfs_hash_for_each_empty(struct cfs_hash *hs,
cfs_hash_for_each_cb_t func, void *data)
{
unsigned i = 0;
int start = 0;
ENTRY;
if (cfs_hash_with_no_lock(hs))
return -EOPNOTSUPP;
if (hs->hs_ops->hs_get == NULL ||
(hs->hs_ops->hs_put == NULL &&
hs->hs_ops->hs_put_locked == NULL))
return -EOPNOTSUPP;
cfs_hash_for_each_enter(hs);
while (cfs_hash_for_each_relax(hs, func, data, &start)) {
CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
hs->hs_name, i++);
}
cfs_hash_for_each_exit(hs);
RETURN(0);
}
EXPORT_SYMBOL(cfs_hash_for_each_empty);
void
cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
cfs_hash_for_each_cb_t func, void *data)
{
struct hlist_head *hhead;
struct hlist_node *hnode;
struct cfs_hash_bd bd;
cfs_hash_for_each_enter(hs);
cfs_hash_lock(hs, 0);
if (hindex >= CFS_HASH_NHLIST(hs))
goto out;
cfs_hash_bd_index_set(hs, hindex, &bd);
cfs_hash_bd_lock(hs, &bd, 0);
hhead = cfs_hash_bd_hhead(hs, &bd);
hlist_for_each(hnode, hhead) {
if (func(hs, &bd, hnode, data))
break;
}
cfs_hash_bd_unlock(hs, &bd, 0);
out:
cfs_hash_unlock(hs, 0);
cfs_hash_for_each_exit(hs);
}
EXPORT_SYMBOL(cfs_hash_hlist_for_each);
/*
* For each item in the libcfs hash @hs which matches the @key call
* the passed callback @func and pass to it as an argument each hash
* item and the private @data. During the callback the bucket lock
* is held so the callback must never sleep.
*/
void
cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
cfs_hash_for_each_cb_t func, void *data)
{
struct hlist_node *hnode;
struct cfs_hash_bd bds[2];
unsigned i;
cfs_hash_lock(hs, 0);
cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
cfs_hash_for_each_bd(bds, 2, i) {
struct hlist_head *hlist = cfs_hash_bd_hhead(hs, &bds[i]);
hlist_for_each(hnode, hlist) {
cfs_hash_bucket_validate(hs, &bds[i], hnode);
if (cfs_hash_keycmp(hs, key, hnode)) {
if (func(hs, &bds[i], hnode, data))
break;
}
}
}
cfs_hash_dual_bd_unlock(hs, bds, 0);
cfs_hash_unlock(hs, 0);
}
EXPORT_SYMBOL(cfs_hash_for_each_key);
/**
* Rehash the libcfs hash @hs to the given @bits. This can be used
* to grow the hash size when excessive chaining is detected, or to
* shrink the hash when it is larger than needed. When the CFS_HASH_REHASH
* flag is set in @hs the libcfs hash may be dynamically rehashed
* during addition or removal if the hash's theta value exceeds
* either the hs->hs_min_theta or hs->max_theta values. By default
* these values are tuned to keep the chained hash depth small, and
* this approach assumes a reasonably uniform hashing function. The
* theta thresholds for @hs are tunable via cfs_hash_set_theta().
*/
void
cfs_hash_rehash_cancel(struct cfs_hash *hs)
{
LASSERT(hs->hs_iterators > 0 || hs->hs_exiting);
while (cfs_hash_is_rehashing(hs)) {
if (cancel_work_sync(&hs->hs_rehash_work)) {
cfs_hash_lock(hs, 1);
hs->hs_rehash_bits = 0;
cfs_hash_unlock(hs, 1);
}
cond_resched();
}
}
void
cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
{
int rc;
LASSERT(cfs_hash_with_rehash(hs) && !cfs_hash_with_no_lock(hs));
cfs_hash_lock(hs, 1);
rc = cfs_hash_rehash_bits(hs);
if (rc <= 0) {
cfs_hash_unlock(hs, 1);
return;
}
hs->hs_rehash_bits = rc;
if (!do_rehash) {
/* launch and return */
queue_work(cfs_rehash_wq, &hs->hs_rehash_work);
cfs_hash_unlock(hs, 1);
return;
}
/* rehash right now */
cfs_hash_unlock(hs, 1);
cfs_hash_rehash_worker(&hs->hs_rehash_work);
}
static int
cfs_hash_rehash_bd(struct cfs_hash *hs, struct cfs_hash_bd *old)
{
struct cfs_hash_bd new;
struct hlist_head *hhead;
struct hlist_node *hnode;
struct hlist_node *pos;
void *key;
int c = 0;
/* hold cfs_hash_lock(hs, 1), so don't need any bucket lock */
cfs_hash_bd_for_each_hlist(hs, old, hhead) {
hlist_for_each_safe(hnode, pos, hhead) {
key = cfs_hash_key(hs, hnode);
LASSERT(key != NULL);
/* Validate hnode is in the correct bucket. */
cfs_hash_bucket_validate(hs, old, hnode);
/*
* Delete from old hash bucket; move to new bucket.
* ops->hs_key must be defined.
*/
cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
hs->hs_rehash_bits, key, &new);
cfs_hash_bd_move_locked(hs, old, &new, hnode);
c++;
}
}
return c;
}
static void
cfs_hash_rehash_worker(struct work_struct *work)
{
struct cfs_hash *hs = container_of(work, struct cfs_hash,
hs_rehash_work);
struct cfs_hash_bucket **bkts;
struct cfs_hash_bd bd;
unsigned int old_size;
unsigned int new_size;
int bsize;
int count = 0;
int rc = 0;
int i;
LASSERT(hs != NULL && cfs_hash_with_rehash(hs));
cfs_hash_lock(hs, 0);
LASSERT(cfs_hash_is_rehashing(hs));
old_size = CFS_HASH_NBKT(hs);
new_size = CFS_HASH_RH_NBKT(hs);
cfs_hash_unlock(hs, 0);
/*
* don't need hs::hs_rwlock for hs::hs_buckets,
* because nobody can change bkt-table except me.
*/
bkts = cfs_hash_buckets_realloc(hs, hs->hs_buckets,
old_size, new_size);
cfs_hash_lock(hs, 1);
if (bkts == NULL) {
rc = -ENOMEM;
goto out;
}
if (bkts == hs->hs_buckets) {
bkts = NULL; /* do nothing */
goto out;
}
rc = __cfs_hash_theta(hs);
if ((rc >= hs->hs_min_theta) && (rc <= hs->hs_max_theta)) {
/* free the new allocated bkt-table */
old_size = new_size;
new_size = CFS_HASH_NBKT(hs);
rc = -EALREADY;
goto out;
}
LASSERT(hs->hs_rehash_buckets == NULL);
hs->hs_rehash_buckets = bkts;
rc = 0;
cfs_hash_for_each_bucket(hs, &bd, i) {
if (cfs_hash_is_exiting(hs)) {
rc = -ESRCH;
/* someone wants to destroy the hash, abort now */
if (old_size < new_size) /* OK to free old bkt-table */
break;
/* it's shrinking, need free new bkt-table */
hs->hs_rehash_buckets = NULL;
old_size = new_size;
new_size = CFS_HASH_NBKT(hs);
goto out;
}
count += cfs_hash_rehash_bd(hs, &bd);
if (count < CFS_HASH_LOOP_HOG ||
cfs_hash_is_iterating(hs)) { /* need to finish ASAP */
continue;
}
count = 0;
cfs_hash_unlock(hs, 1);
cond_resched();
cfs_hash_lock(hs, 1);
}
hs->hs_rehash_count++;
bkts = hs->hs_buckets;
hs->hs_buckets = hs->hs_rehash_buckets;
hs->hs_rehash_buckets = NULL;
hs->hs_cur_bits = hs->hs_rehash_bits;
out:
hs->hs_rehash_bits = 0;
bsize = cfs_hash_bkt_size(hs);
cfs_hash_unlock(hs, 1);
/* can't refer to @hs anymore because it could be destroyed */
if (bkts != NULL)
cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
if (rc != 0)
CDEBUG(D_INFO, "early quit of rehashing: %d\n", rc);
}
/**
* Rehash the object referenced by @hnode in the libcfs hash @hs. The
* @old_key must be provided to locate the objects previous location
* in the hash, and the @new_key will be used to reinsert the object.
* Use this function instead of a cfs_hash_add() + cfs_hash_del()
* combo when it is critical that there is no window in time where the
* object is missing from the hash. When an object is being rehashed
* the registered cfs_hash_get() and cfs_hash_put() functions will
* not be called.
*/
void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
void *new_key, struct hlist_node *hnode)
{
struct cfs_hash_bd bds[3];
struct cfs_hash_bd old_bds[2];
struct cfs_hash_bd new_bd;
LASSERT(!hlist_unhashed(hnode));
cfs_hash_lock(hs, 0);
cfs_hash_dual_bd_get(hs, old_key, old_bds);
cfs_hash_bd_get(hs, new_key, &new_bd);
bds[0] = old_bds[0];
bds[1] = old_bds[1];
bds[2] = new_bd;
/* NB: bds[0] and bds[1] are ordered already */
cfs_hash_bd_order(&bds[1], &bds[2]);
cfs_hash_bd_order(&bds[0], &bds[1]);
cfs_hash_multi_bd_lock(hs, bds, 3, 1);
if (likely(old_bds[1].bd_bucket == NULL)) {
cfs_hash_bd_move_locked(hs, &old_bds[0], &new_bd, hnode);
} else {
cfs_hash_dual_bd_finddel_locked(hs, old_bds, old_key, hnode);
cfs_hash_bd_add_locked(hs, &new_bd, hnode);
}
/* overwrite key inside locks, otherwise may screw up with
* other operations, i.e: rehash */
cfs_hash_keycpy(hs, hnode, new_key);
cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
cfs_hash_unlock(hs, 0);
}
EXPORT_SYMBOL(cfs_hash_rehash_key);
