diff options
Diffstat (limited to 'drivers/staging/lustre/lustre/libcfs/hash.c')
| -rw-r--r-- | drivers/staging/lustre/lustre/libcfs/hash.c | 2123 |
1 files changed, 2123 insertions, 0 deletions
diff --git a/drivers/staging/lustre/lustre/libcfs/hash.c b/drivers/staging/lustre/lustre/libcfs/hash.c new file mode 100644 index 000000000000..98c76dfac3dd --- /dev/null +++ b/drivers/staging/lustre/lustre/libcfs/hash.c @@ -0,0 +1,2123 @@ +/* + * GPL HEADER START + * + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 only, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License version 2 for more details (a copy is included + * in the LICENSE file that accompanied this code). + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; If not, see + * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + * GPL HEADER END + */ +/* + * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved. + * Use is subject to license terms. + * + * Copyright (c) 2011, 2012, Intel Corporation. + */ +/* + * This file is part of Lustre, http://www.lustre.org/ + * Lustre is a trademark of Sun Microsystems, Inc. + * + * libcfs/libcfs/hash.c + * + * 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(intead 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 speicify 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/libcfs/libcfs.h> +#include <linux/seq_file.h> + +#if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 +static unsigned int warn_on_depth = 8; +CFS_MODULE_PARM(warn_on_depth, "i", uint, 0644, + "warning when hash depth is high."); +#endif + +struct cfs_wi_sched *cfs_sched_rehash; + +static inline void +cfs_hash_nl_lock(cfs_hash_lock_t *lock, int exclusive) {} + +static inline void +cfs_hash_nl_unlock(cfs_hash_lock_t *lock, int exclusive) {} + +static inline void +cfs_hash_spin_lock(cfs_hash_lock_t *lock, int exclusive) +{ + spin_lock(&lock->spin); +} + +static inline void +cfs_hash_spin_unlock(cfs_hash_lock_t *lock, int exclusive) +{ + spin_unlock(&lock->spin); +} + +static inline void +cfs_hash_rw_lock(cfs_hash_lock_t *lock, int exclusive) +{ + if (!exclusive) + read_lock(&lock->rw); + else + write_lock(&lock->rw); +} + +static inline void +cfs_hash_rw_unlock(cfs_hash_lock_t *lock, int exclusive) +{ + if (!exclusive) + read_unlock(&lock->rw); + else + write_unlock(&lock->rw); +} + +/** No lock hash */ +static cfs_hash_lock_ops_t 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 cfs_hash_lock_ops_t 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 cfs_hash_lock_ops_t 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 cfs_hash_lock_ops_t 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 cfs_hash_lock_ops_t 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 cfs_hash_lock_ops_t 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, +}; + +static void +cfs_hash_lock_setup(cfs_hash_t *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)) { + 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 + LBUG(); + } +} + +/** + * Simple hash head without depth tracking + * new element is always added to head of hlist + */ +typedef struct { + struct hlist_head hh_head; /**< entries list */ +} cfs_hash_head_t; + +static int +cfs_hash_hh_hhead_size(cfs_hash_t *hs) +{ + return sizeof(cfs_hash_head_t); +} + +static struct hlist_head * +cfs_hash_hh_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd) +{ + cfs_hash_head_t *head = (cfs_hash_head_t *)&bd->bd_bucket->hsb_head[0]; + + return &head[bd->bd_offset].hh_head; +} + +static int +cfs_hash_hh_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_t *hs, cfs_hash_bd_t *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 + */ +typedef struct { + struct hlist_head hd_head; /**< entries list */ + unsigned int hd_depth; /**< list length */ +} cfs_hash_head_dep_t; + +static int +cfs_hash_hd_hhead_size(cfs_hash_t *hs) +{ + return sizeof(cfs_hash_head_dep_t); +} + +static struct hlist_head * +cfs_hash_hd_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd) +{ + cfs_hash_head_dep_t *head; + + head = (cfs_hash_head_dep_t *)&bd->bd_bucket->hsb_head[0]; + return &head[bd->bd_offset].hd_head; +} + +static int +cfs_hash_hd_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode) +{ + cfs_hash_head_dep_t *hh = container_of(cfs_hash_hd_hhead(hs, bd), + cfs_hash_head_dep_t, hd_head); + hlist_add_head(hnode, &hh->hd_head); + return ++hh->hd_depth; +} + +static int +cfs_hash_hd_hnode_del(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode) +{ + cfs_hash_head_dep_t *hh = container_of(cfs_hash_hd_hhead(hs, bd), + cfs_hash_head_dep_t, 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 + */ +typedef struct { + struct hlist_head dh_head; /**< entries list */ + struct hlist_node *dh_tail; /**< the last entry */ +} cfs_hash_dhead_t; + +static int +cfs_hash_dh_hhead_size(cfs_hash_t *hs) +{ + return sizeof(cfs_hash_dhead_t); +} + +static struct hlist_head * +cfs_hash_dh_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd) +{ + cfs_hash_dhead_t *head; + + head = (cfs_hash_dhead_t *)&bd->bd_bucket->hsb_head[0]; + return &head[bd->bd_offset].dh_head; +} + +static int +cfs_hash_dh_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode) +{ + cfs_hash_dhead_t *dh = container_of(cfs_hash_dh_hhead(hs, bd), + cfs_hash_dhead_t, dh_head); + + if (dh->dh_tail != NULL) /* not empty */ + hlist_add_after(dh->dh_tail, hnode); + 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(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnd) +{ + cfs_hash_dhead_t *dh = container_of(cfs_hash_dh_hhead(hs, bd), + cfs_hash_dhead_t, 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 + */ +typedef struct { + struct hlist_head dd_head; /**< entries list */ + struct hlist_node *dd_tail; /**< the last entry */ + unsigned int dd_depth; /**< list length */ +} cfs_hash_dhead_dep_t; + +static int +cfs_hash_dd_hhead_size(cfs_hash_t *hs) +{ + return sizeof(cfs_hash_dhead_dep_t); +} + +static struct hlist_head * +cfs_hash_dd_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd) +{ + cfs_hash_dhead_dep_t *head; + + head = (cfs_hash_dhead_dep_t *)&bd->bd_bucket->hsb_head[0]; + return &head[bd->bd_offset].dd_head; +} + +static int +cfs_hash_dd_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode) +{ + cfs_hash_dhead_dep_t *dh = container_of(cfs_hash_dd_hhead(hs, bd), + cfs_hash_dhead_dep_t, dd_head); + + if (dh->dd_tail != NULL) /* not empty */ + hlist_add_after(dh->dd_tail, hnode); + 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(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnd) +{ + cfs_hash_dhead_dep_t *dh = container_of(cfs_hash_dd_hhead(hs, bd), + cfs_hash_dhead_dep_t, 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 cfs_hash_hlist_ops_t 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 cfs_hash_hlist_ops_t 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 cfs_hash_hlist_ops_t 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 cfs_hash_hlist_ops_t 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(cfs_hash_t *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(cfs_hash_t *hs, cfs_hash_bucket_t **bkts, + unsigned int bits, const void *key, cfs_hash_bd_t *bd) +{ + unsigned int index = cfs_hash_id(hs, key, (1U << bits) - 1); + + 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(cfs_hash_t *hs, const void *key, cfs_hash_bd_t *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(cfs_hash_t *hs, cfs_hash_bd_t *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); + + cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi); +# endif +} + +void +cfs_hash_bd_add_locked(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_t *hs, cfs_hash_bd_t *bd_old, + cfs_hash_bd_t *bd_new, struct hlist_node *hnode) +{ + cfs_hash_bucket_t *obkt = bd_old->bd_bucket; + cfs_hash_bucket_t *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++; +} +EXPORT_SYMBOL(cfs_hash_bd_move_locked); + +enum { + /** always set, for sanity (avoid ZERO intent) */ + CFS_HS_LOOKUP_MASK_FIND = 1 << 0, + /** return entry with a ref */ + CFS_HS_LOOKUP_MASK_REF = 1 << 1, + /** add entry if not existing */ + CFS_HS_LOOKUP_MASK_ADD = 1 << 2, + /** delete entry, ignore other masks */ + CFS_HS_LOOKUP_MASK_DEL = 1 << 3, +}; + +typedef 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) +} cfs_hash_lookup_intent_t; + +static struct hlist_node * +cfs_hash_bd_lookup_intent(cfs_hash_t *hs, cfs_hash_bd_t *bd, + const void *key, struct hlist_node *hnode, + cfs_hash_lookup_intent_t 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(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_t *hs, cfs_hash_bd_t *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); + +struct hlist_node * +cfs_hash_bd_findadd_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd, + const void *key, struct hlist_node *hnode, + int noref) +{ + return cfs_hash_bd_lookup_intent(hs, bd, key, hnode, + CFS_HS_LOOKUP_IT_ADD | + (!noref * CFS_HS_LOOKUP_MASK_REF)); +} +EXPORT_SYMBOL(cfs_hash_bd_findadd_locked); + +struct hlist_node * +cfs_hash_bd_finddel_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd, + const void *key, struct hlist_node *hnode) +{ + /* hnode can be NULL, we find the first item with @key */ + return cfs_hash_bd_lookup_intent(hs, bd, key, hnode, + CFS_HS_LOOKUP_IT_FINDDEL); +} +EXPORT_SYMBOL(cfs_hash_bd_finddel_locked); + +static void +cfs_hash_multi_bd_lock(cfs_hash_t *hs, cfs_hash_bd_t *bds, + unsigned n, int excl) +{ + cfs_hash_bucket_t *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(cfs_hash_t *hs, cfs_hash_bd_t *bds, + unsigned n, int excl) +{ + cfs_hash_bucket_t *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(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_t *hs, + cfs_hash_bd_t *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 { + cfs_hash_bd_t 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(cfs_hash_t *hs, cfs_hash_bd_t *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(cfs_hash_bd_t *bd1, cfs_hash_bd_t *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) { /* swab bd1 and bd2 */ + cfs_hash_bd_t tmp; + + tmp = *bd2; + *bd2 = *bd1; + *bd1 = tmp; + } +} + +void +cfs_hash_dual_bd_get(cfs_hash_t *hs, const void *key, cfs_hash_bd_t *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]); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_get); + +void +cfs_hash_dual_bd_lock(cfs_hash_t *hs, cfs_hash_bd_t *bds, int excl) +{ + cfs_hash_multi_bd_lock(hs, bds, 2, excl); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_lock); + +void +cfs_hash_dual_bd_unlock(cfs_hash_t *hs, cfs_hash_bd_t *bds, int excl) +{ + cfs_hash_multi_bd_unlock(hs, bds, 2, excl); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_unlock); + +struct hlist_node * +cfs_hash_dual_bd_lookup_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds, + const void *key) +{ + return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_lookup_locked); + +struct hlist_node * +cfs_hash_dual_bd_findadd_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds, + const void *key, struct hlist_node *hnode, + int noref) +{ + return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key, + hnode, noref); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_findadd_locked); + +struct hlist_node * +cfs_hash_dual_bd_finddel_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds, + const void *key, struct hlist_node *hnode) +{ + return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode); +} +EXPORT_SYMBOL(cfs_hash_dual_bd_finddel_locked); + +static void +cfs_hash_buckets_free(cfs_hash_bucket_t **buckets, + int bkt_size, int prev_size, int size) +{ + int i; + + for (i = prev_size; i < size; i++) { + if (buckets[i] != NULL) + 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 cfs_hash_bucket_t ** +cfs_hash_buckets_realloc(cfs_hash_t *hs, cfs_hash_bucket_t **old_bkts, + unsigned int old_size, unsigned int new_size) +{ + cfs_hash_bucket_t **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; + cfs_hash_bd_t 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 + 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 int cfs_hash_rehash_worker(cfs_workitem_t *wi); + +#if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 +static int cfs_hash_dep_print(cfs_workitem_t *wi) +{ + cfs_hash_t *hs = container_of(wi, cfs_hash_t, hs_dep_wi); + 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(cfs_hash_t *hs) +{ + spin_lock_init(&hs->hs_dep_lock); + cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print); +} + +static void cfs_hash_depth_wi_cancel(cfs_hash_t *hs) +{ + if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi)) + return; + + spin_lock(&hs->hs_dep_lock); + while (hs->hs_dep_bits != 0) { + spin_unlock(&hs->hs_dep_lock); + cond_resched(); + spin_lock(&hs->hs_dep_lock); + } + spin_unlock(&hs->hs_dep_lock); +} + +#else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */ + +static inline void cfs_hash_depth_wi_init(cfs_hash_t *hs) {} +static inline void cfs_hash_depth_wi_cancel(cfs_hash_t *hs) {} + +#endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */ + +cfs_hash_t * +cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits, + unsigned bkt_bits, unsigned extra_bytes, + unsigned min_theta, unsigned max_theta, + cfs_hash_ops_t *ops, unsigned flags) +{ + cfs_hash_t *hs; + int len; + + ENTRY; + + CLASSERT(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_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, offsetof(cfs_hash_t, hs_name[len])); + if (hs == NULL) + RETURN(NULL); + + strncpy(hs->hs_name, name, len); + hs->hs_name[len - 1] = '\0'; + hs->hs_flags = flags; + + atomic_set(&hs->hs_refcount, 1); + 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; + cfs_wi_init(&hs->hs_rehash_wi, hs, 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, offsetof(cfs_hash_t, hs_name[len])); + RETURN(NULL); +} +EXPORT_SYMBOL(cfs_hash_create); + +/** + * Cleanup libcfs hash @hs. + */ +static void +cfs_hash_destroy(cfs_hash_t *hs) +{ + struct hlist_node *hnode; + struct hlist_node *pos; + cfs_hash_bd_t 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, offsetof(cfs_hash_t, hs_name[i])); + + EXIT; +} + +cfs_hash_t *cfs_hash_getref(cfs_hash_t *hs) +{ + if (atomic_inc_not_zero(&hs->hs_refcount)) + return hs; + return NULL; +} +EXPORT_SYMBOL(cfs_hash_getref); + +void cfs_hash_putref(cfs_hash_t *hs) +{ + if (atomic_dec_and_test(&hs->hs_refcount)) + cfs_hash_destroy(hs); +} +EXPORT_SYMBOL(cfs_hash_putref); + +static inline int +cfs_hash_rehash_bits(cfs_hash_t *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(cfs_hash_t *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(cfs_hash_t *hs, const void *key, struct hlist_node *hnode) +{ + cfs_hash_bd_t 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(cfs_hash_t *hs, const void *key, + struct hlist_node *hnode, int noref) +{ + struct hlist_node *ehnode; + cfs_hash_bd_t bds[2]; + int bits = 0; + + LASSERT(hlist_unhashed(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(cfs_hash_t *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(cfs_hash_t *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(cfs_hash_t *hs, const void *key, struct hlist_node *hnode) +{ + void *obj = NULL; + int bits = 0; + cfs_hash_bd_t 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(cfs_hash_t *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(cfs_hash_t *hs, const void *key) +{ + void *obj = NULL; + struct hlist_node *hnode; + cfs_hash_bd_t 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(cfs_hash_t *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 finsih rehash ASAP when seeing this. + */ + hs->hs_iterating = 1; + + cfs_hash_lock(hs, 1); + hs->hs_iterators++; + + /* NB: iteration is mostly called by service thread, + * we tend to cancel pending rehash-requst, instead of + * blocking service thread, we will relaunch rehash request + * after iteration */ + if (cfs_hash_is_rehashing(hs)) + cfs_hash_rehash_cancel_locked(hs); + cfs_hash_unlock(hs, 1); +} + +static void +cfs_hash_for_each_exit(cfs_hash_t *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(cfs_hash_t *hs, cfs_hash_for_each_cb_t func, + void *data, int remove_safe) +{ + struct hlist_node *hnode; + struct hlist_node *pos; + cfs_hash_bd_t 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); +} + +typedef struct { + cfs_hash_cond_opt_cb_t func; + void *arg; +} cfs_hash_cond_arg_t; + +static int +cfs_hash_cond_del_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode, void *data) +{ + cfs_hash_cond_arg_t *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(cfs_hash_t *hs, cfs_hash_cond_opt_cb_t func, void *data) +{ + cfs_hash_cond_arg_t 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(cfs_hash_t *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(cfs_hash_t *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(cfs_hash_t *hs, cfs_hash_bd_t *bd, + struct hlist_node *hnode, void *data) +{ + *(int *)data = 0; + return 1; /* return 1 to break the loop */ +} + +int +cfs_hash_is_empty(cfs_hash_t *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(cfs_hash_t *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(cfs_hash_t *hs, cfs_hash_for_each_cb_t func, void *data) +{ + struct hlist_node *hnode; + struct hlist_node *tmp; + cfs_hash_bd_t bd; + __u32 version; + int count = 0; + int stop_on_change; + int rc; + int i; + ENTRY; + + stop_on_change = cfs_hash_with_rehash_key(hs) || + !cfs_hash_with_no_itemref(hs) || + CFS_HOP(hs, put_locked) == NULL; + 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, 0); + version = cfs_hash_bd_version_get(&bd); + + cfs_hash_bd_for_each_hlist(hs, &bd, hhead) { + for (hnode = hhead->first; hnode != NULL;) { + cfs_hash_bucket_validate(hs, &bd, hnode); + cfs_hash_get(hs, hnode); + cfs_hash_bd_unlock(hs, &bd, 0); + cfs_hash_unlock(hs, 0); + + rc = func(hs, &bd, hnode, data); + if (stop_on_change) + cfs_hash_put(hs, hnode); + cond_resched(); + count++; + + cfs_hash_lock(hs, 0); + cfs_hash_bd_lock(hs, &bd, 0); + if (!stop_on_change) { + tmp = hnode->next; + cfs_hash_put_locked(hs, hnode); + hnode = tmp; + } else { /* bucket changed? */ + if (version != + cfs_hash_bd_version_get(&bd)) + break; + /* safe to continue because no change */ + hnode = hnode->next; + } + if (rc) /* callback wants to break iteration */ + break; + } + } + cfs_hash_bd_unlock(hs, &bd, 0); + } + cfs_hash_unlock(hs, 0); + + return count; +} + +int +cfs_hash_for_each_nolock(cfs_hash_t *hs, + cfs_hash_for_each_cb_t func, void *data) +{ + ENTRY; + + if (cfs_hash_with_no_lock(hs) || + cfs_hash_with_rehash_key(hs) || + !cfs_hash_with_no_itemref(hs)) + RETURN(-EOPNOTSUPP); + + if (CFS_HOP(hs, get) == NULL || + (CFS_HOP(hs, put) == NULL && + CFS_HOP(hs, put_locked) == NULL)) + RETURN(-EOPNOTSUPP); + + cfs_hash_for_each_enter(hs); + cfs_hash_for_each_relax(hs, func, data); + 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(cfs_hash_t *hs, + cfs_hash_for_each_cb_t func, void *data) +{ + unsigned i = 0; + ENTRY; + + if (cfs_hash_with_no_lock(hs)) + return -EOPNOTSUPP; + + if (CFS_HOP(hs, get) == NULL || + (CFS_HOP(hs, put) == NULL && + CFS_HOP(hs, put_locked) == NULL)) + return -EOPNOTSUPP; + + cfs_hash_for_each_enter(hs); + while (cfs_hash_for_each_relax(hs, func, data)) { + 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(cfs_hash_t *hs, unsigned hindex, + cfs_hash_for_each_cb_t func, void *data) +{ + struct hlist_head *hhead; + struct hlist_node *hnode; + cfs_hash_bd_t 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(cfs_hash_t *hs, const void *key, + cfs_hash_for_each_cb_t func, void *data) +{ + struct hlist_node *hnode; + cfs_hash_bd_t 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_locked(cfs_hash_t *hs) +{ + int i; + + /* need hold cfs_hash_lock(hs, 1) */ + LASSERT(cfs_hash_with_rehash(hs) && + !cfs_hash_with_no_lock(hs)); + + if (!cfs_hash_is_rehashing(hs)) + return; + + if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) { + hs->hs_rehash_bits = 0; + return; + } + + for (i = 2; cfs_hash_is_rehashing(hs); i++) { + cfs_hash_unlock(hs, 1); + /* raise console warning while waiting too long */ + CDEBUG(IS_PO2(i >> 3) ? D_WARNING : D_INFO, + "hash %s is still rehashing, rescheded %d\n", + hs->hs_name, i - 1); + cond_resched(); + cfs_hash_lock(hs, 1); + } +} +EXPORT_SYMBOL(cfs_hash_rehash_cancel_locked); + +void +cfs_hash_rehash_cancel(cfs_hash_t *hs) +{ + cfs_hash_lock(hs, 1); + cfs_hash_rehash_cancel_locked(hs); + cfs_hash_unlock(hs, 1); +} +EXPORT_SYMBOL(cfs_hash_rehash_cancel); + +int +cfs_hash_rehash(cfs_hash_t *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 rc; + } + + hs->hs_rehash_bits = rc; + if (!do_rehash) { + /* launch and return */ + cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi); + cfs_hash_unlock(hs, 1); + return 0; + } + + /* rehash right now */ + cfs_hash_unlock(hs, 1); + + return cfs_hash_rehash_worker(&hs->hs_rehash_wi); +} +EXPORT_SYMBOL(cfs_hash_rehash); + +static int +cfs_hash_rehash_bd(cfs_hash_t *hs, cfs_hash_bd_t *old) +{ + cfs_hash_bd_t 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 int +cfs_hash_rehash_worker(cfs_workitem_t *wi) +{ + cfs_hash_t *hs = container_of(wi, cfs_hash_t, hs_rehash_wi); + cfs_hash_bucket_t **bkts; + cfs_hash_bd_t 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; + if (rc == -ESRCH) /* never be scheduled again */ + cfs_wi_exit(cfs_sched_rehash, wi); + 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 of rehashing: %d\n", rc); + /* return 1 only if cfs_wi_exit is called */ + return rc == -ESRCH; +} + +/** + * 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(cfs_hash_t *hs, const void *old_key, + void *new_key, struct hlist_node *hnode) +{ + cfs_hash_bd_t bds[3]; + cfs_hash_bd_t old_bds[2]; + cfs_hash_bd_t 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, new_key, hnode); + + cfs_hash_multi_bd_unlock(hs, bds, 3, 1); + cfs_hash_unlock(hs, 0); +} +EXPORT_SYMBOL(cfs_hash_rehash_key); + +int cfs_hash_debug_header(struct seq_file *m) +{ + return seq_printf(m, "%-*s%6s%6s%6s%6s%6s%6s%6s%7s%8s%8s%8s%s\n", + CFS_HASH_BIGNAME_LEN, + "name", "cur", "min", "max", "theta", "t-min", "t-max", + "flags", "rehash", "count", "maxdep", "maxdepb", + " distribution"); +} +EXPORT_SYMBOL(cfs_hash_debug_header); + +static cfs_hash_bucket_t ** +cfs_hash_full_bkts(cfs_hash_t *hs) +{ + /* NB: caller should hold hs->hs_rwlock if REHASH is set */ + if (hs->hs_rehash_buckets == NULL) + return hs->hs_buckets; + + LASSERT(hs->hs_rehash_bits != 0); + return hs->hs_rehash_bits > hs->hs_cur_bits ? + hs->hs_rehash_buckets : hs->hs_buckets; +} + +static unsigned int +cfs_hash_full_nbkt(cfs_hash_t *hs) +{ + /* NB: caller should hold hs->hs_rwlock if REHASH is set */ + if (hs->hs_rehash_buckets == NULL) + return CFS_HASH_NBKT(hs); + + LASSERT(hs->hs_rehash_bits != 0); + return hs->hs_rehash_bits > hs->hs_cur_bits ? + CFS_HASH_RH_NBKT(hs) : CFS_HASH_NBKT(hs); +} + +int cfs_hash_debug_str(cfs_hash_t *hs, struct seq_file *m) +{ + int dist[8] = { 0, }; + int maxdep = -1; + int maxdepb = -1; + int total = 0; + int theta; + int i; + + cfs_hash_lock(hs, 0); + theta = __cfs_hash_theta(hs); + + seq_printf(m, "%-*s %5d %5d %5d %d.%03d %d.%03d %d.%03d 0x%02x %6d ", + CFS_HASH_BIGNAME_LEN, hs->hs_name, + 1 << hs->hs_cur_bits, 1 << hs->hs_min_bits, + 1 << hs->hs_max_bits, + __cfs_hash_theta_int(theta), __cfs_hash_theta_frac(theta), + __cfs_hash_theta_int(hs->hs_min_theta), + __cfs_hash_theta_frac(hs->hs_min_theta), + __cfs_hash_theta_int(hs->hs_max_theta), + __cfs_hash_theta_frac(hs->hs_max_theta), + hs->hs_flags, hs->hs_rehash_count); + + /* + * The distribution is a summary of the chained hash depth in + * each of the libcfs hash buckets. Each buckets hsb_count is + * divided by the hash theta value and used to generate a + * histogram of the hash distribution. A uniform hash will + * result in all hash buckets being close to the average thus + * only the first few entries in the histogram will be non-zero. + * If you hash function results in a non-uniform hash the will + * be observable by outlier bucks in the distribution histogram. + * + * Uniform hash distribution: 128/128/0/0/0/0/0/0 + * Non-Uniform hash distribution: 128/125/0/0/0/0/2/1 + */ + for (i = 0; i < cfs_hash_full_nbkt(hs); i++) { + cfs_hash_bd_t bd; + + bd.bd_bucket = cfs_hash_full_bkts(hs)[i]; + cfs_hash_bd_lock(hs, &bd, 0); + if (maxdep < bd.bd_bucket->hsb_depmax) { + maxdep = bd.bd_bucket->hsb_depmax; + maxdepb = ffz(~maxdep); + } + total += bd.bd_bucket->hsb_count; + dist[min(__cfs_fls(bd.bd_bucket->hsb_count/max(theta,1)),7)]++; + cfs_hash_bd_unlock(hs, &bd, 0); + } + + seq_printf(m, "%7d %7d %7d ", total, maxdep, maxdepb); + for (i = 0; i < 8; i++) + seq_printf(m, "%d%c", dist[i], (i == 7) ? '\n' : '/'); + + cfs_hash_unlock(hs, 0); + + return 0; +} +EXPORT_SYMBOL(cfs_hash_debug_str); |