--- /dev/null
+/*
+ * 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(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 "../../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;
+module_param(warn_on_depth, uint, 0644);
+MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
+#endif
+
+struct cfs_wi_sched *cfs_sched_rehash;
+
+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);
+}
+
+/** 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(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)) {
+ 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(struct cfs_hash *hs)
+{
+ return sizeof(cfs_hash_head_t);
+}
+
+static struct hlist_head *
+cfs_hash_hh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *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(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
+ */
+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(struct cfs_hash *hs)
+{
+ return sizeof(cfs_hash_head_dep_t);
+}
+
+static struct hlist_head *
+cfs_hash_hd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs)
+{
+ return sizeof(cfs_hash_dhead_t);
+}
+
+static struct hlist_head *
+cfs_hash_dh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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_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)
+{
+ 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(struct cfs_hash *hs)
+{
+ return sizeof(cfs_hash_dhead_dep_t);
+}
+
+static struct hlist_head *
+cfs_hash_dd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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_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)
+{
+ 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(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, (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(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);
+
+ cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
+# 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++;
+}
+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(struct cfs_hash *hs, struct cfs_hash_bd *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(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);
+
+struct hlist_node *
+cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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(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) { /* swab bd1 and bd2 */
+ struct cfs_hash_bd tmp;
+
+ tmp = *bd2;
+ *bd2 = *bd1;
+ *bd1 = tmp;
+ }
+}
+
+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]);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_get);
+
+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);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_lock);
+
+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);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_unlock);
+
+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);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_lookup_locked);
+
+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);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_findadd_locked);
+
+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);
+}
+EXPORT_SYMBOL(cfs_hash_dual_bd_finddel_locked);
+
+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++) {
+ 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 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
+ 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)
+{
+ struct cfs_hash *hs = container_of(wi, struct cfs_hash, 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(struct cfs_hash *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(struct cfs_hash *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(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(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)
+{
+ struct cfs_hash *hs;
+ int len;
+
+ 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(struct cfs_hash, 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(struct cfs_hash, hs_name[len]));
+ return NULL;
+}
+EXPORT_SYMBOL(cfs_hash_create);
+
+/**
+ * Cleanup libcfs hash @hs.
+ */
+static void
+cfs_hash_destroy(struct cfs_hash *hs)
+{
+ struct hlist_node *hnode;
+ struct hlist_node *pos;
+ struct cfs_hash_bd bd;
+ int i;
+
+ 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(struct cfs_hash, hs_name[i]));
+}
+
+struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs)
+{
+ if (atomic_inc_not_zero(&hs->hs_refcount))
+ return hs;
+ return NULL;
+}
+EXPORT_SYMBOL(cfs_hash_getref);
+
+void cfs_hash_putref(struct cfs_hash *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(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;
+
+ 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(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++;
+
+ /* 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_locked(hs);
+ cfs_hash_unlock(hs, 1);
+}
+
+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;
+
+ 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(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *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(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) {
+ struct hlist_node *hnode;
+ struct hlist_node *tmp;
+ struct cfs_hash_bd bd;
+ __u32 version;
+ int count = 0;
+ int stop_on_change;
+ int rc;
+ int i;
+
+ stop_on_change = cfs_hash_with_rehash_key(hs) ||
+ !cfs_hash_with_no_itemref(hs) ||
+ hs->hs_ops->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(struct cfs_hash *hs,
+ cfs_hash_for_each_cb_t func, void *data) {
+ 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);
+ 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;
+
+ 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)) {
+ 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_locked(struct cfs_hash *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(struct cfs_hash *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(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 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(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 int
+cfs_hash_rehash_worker(cfs_workitem_t *wi)
+{
+ struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_rehash_wi);
+ 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;
+ 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 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(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, new_key, hnode);
+
+ cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
+ cfs_hash_unlock(hs, 0);
+}
+EXPORT_SYMBOL(cfs_hash_rehash_key);
+
+void cfs_hash_debug_header(struct seq_file *m)
+{
+ seq_printf(m, "%-*s cur min max theta t-min t-max flags rehash count maxdep maxdepb distribution\n",
+ CFS_HASH_BIGNAME_LEN, "name");
+}
+EXPORT_SYMBOL(cfs_hash_debug_header);
+
+static struct cfs_hash_bucket **
+cfs_hash_full_bkts(struct cfs_hash *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(struct cfs_hash *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);
+}
+
+void cfs_hash_debug_str(struct cfs_hash *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++) {
+ struct cfs_hash_bd 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(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);
+}
+EXPORT_SYMBOL(cfs_hash_debug_str);
Code Review / kvmfornfv.git / blobdiff