[Cluster-devel] [GFS2 PATCH 2/2] GFS2: Use resizable hash table for glocks
Bob Peterson
rpeterso at redhat.com
Thu Jul 9 18:25:45 UTC 2015
This patch changes the glock hash table from a normal hash table to
a resizable hash table, which scales better. This also simplifies
a lot of code.
---
fs/gfs2/glock.c | 282 +++++++++++++++++++++----------------------------------
fs/gfs2/incore.h | 4 +-
2 files changed, 111 insertions(+), 175 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 25e0389..813de00 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -34,6 +34,7 @@
#include <linux/percpu.h>
#include <linux/list_sort.h>
#include <linux/lockref.h>
+#include <linux/rhashtable.h>
#include "gfs2.h"
#include "incore.h"
@@ -51,8 +52,12 @@
struct gfs2_glock_iter {
int hash; /* hash bucket index */
- unsigned nhash; /* Index within current bucket */
struct gfs2_sbd *sdp; /* incore superblock */
+};
+
+struct gfs2_glock_rht_iter {
+ struct gfs2_sbd *sdp; /* incore superblock */
+ struct rhashtable_iter hti; /* rhashtable iterator */
struct gfs2_glock *gl; /* current glock struct */
loff_t last_pos; /* last position */
};
@@ -70,44 +75,20 @@ static DEFINE_SPINLOCK(lru_lock);
#define GFS2_GL_HASH_SHIFT 15
#define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT)
-#define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1)
-
-static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
-static struct dentry *gfs2_root;
-
-/**
- * gl_hash() - Turn glock number into hash bucket number
- * @lock: The glock number
- *
- * Returns: The number of the corresponding hash bucket
- */
-
-static unsigned int gl_hash(const struct gfs2_sbd *sdp,
- const struct lm_lockname *name)
-{
- unsigned int h;
-
- h = jhash(&name->ln_number, sizeof(u64), 0);
- h = jhash(&name->ln_type, sizeof(unsigned int), h);
- h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
- h &= GFS2_GL_HASH_MASK;
-
- return h;
-}
-static inline void spin_lock_bucket(unsigned int hash)
-{
- hlist_bl_lock(&gl_hash_table[hash]);
-}
+struct rhashtable_params ht_parms = {
+ .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
+ .key_len = sizeof(struct lm_lockname),
+ .key_offset = offsetof(struct gfs2_glock, gl_name),
+ .head_offset = offsetof(struct gfs2_glock, gl_node),
+ .hashfn = jhash,
+};
-static inline void spin_unlock_bucket(unsigned int hash)
-{
- hlist_bl_unlock(&gl_hash_table[hash]);
-}
+static struct rhashtable gl_hash_table;
-static void gfs2_glock_dealloc(struct rcu_head *rcu)
+void gfs2_glock_free(struct gfs2_glock *gl)
{
- struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
+ struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
if (gl->gl_ops->go_flags & GLOF_ASPACE) {
kmem_cache_free(gfs2_glock_aspace_cachep, gl);
@@ -115,13 +96,6 @@ static void gfs2_glock_dealloc(struct rcu_head *rcu)
kfree(gl->gl_lksb.sb_lvbptr);
kmem_cache_free(gfs2_glock_cachep, gl);
}
-}
-
-void gfs2_glock_free(struct gfs2_glock *gl)
-{
- struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
-
- call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
if (atomic_dec_and_test(&sdp->sd_glock_disposal))
wake_up(&sdp->sd_glock_wait);
}
@@ -202,9 +176,8 @@ void gfs2_glock_put(struct gfs2_glock *gl)
gfs2_glock_remove_from_lru(gl);
spin_unlock(&gl->gl_lockref.lock);
- spin_lock_bucket(gl->gl_hash);
- hlist_bl_del_rcu(&gl->gl_list);
- spin_unlock_bucket(gl->gl_hash);
+ if (gl->gl_node.next != NULL)
+ rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
trace_gfs2_glock_put(gl);
@@ -212,30 +185,6 @@ void gfs2_glock_put(struct gfs2_glock *gl)
}
/**
- * search_bucket() - Find struct gfs2_glock by lock number
- * @bucket: the bucket to search
- * @name: The lock name
- *
- * Returns: NULL, or the struct gfs2_glock with the requested number
- */
-
-static struct gfs2_glock *search_bucket(unsigned int hash,
- const struct lm_lockname *name)
-{
- struct gfs2_glock *gl;
- struct hlist_bl_node *h;
-
- hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
- if (!lm_name_equal(&gl->gl_name, name))
- continue;
- if (lockref_get_not_dead(&gl->gl_lockref))
- return gl;
- }
-
- return NULL;
-}
-
-/**
* may_grant - check if its ok to grant a new lock
* @gl: The glock
* @gh: The lock request which we wish to grant
@@ -704,14 +653,14 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
struct lm_lockname name = { .ln_number = number,
.ln_type = glops->go_type,
.ln_sbd = sdp };
- struct gfs2_glock *gl, *tmp;
- unsigned int hash = gl_hash(sdp, &name);
+ struct gfs2_glock *gl, *tmp = NULL;
struct address_space *mapping;
struct kmem_cache *cachep;
+ int ret, tries = 0;
- rcu_read_lock();
- gl = search_bucket(hash, &name);
- rcu_read_unlock();
+ gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
+ if (gl && !lockref_get_not_dead(&gl->gl_lockref))
+ gl = NULL;
*glp = gl;
if (gl)
@@ -738,13 +687,13 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
}
atomic_inc(&sdp->sd_glock_disposal);
+ gl->gl_node.next = NULL;
gl->gl_flags = 0;
gl->gl_name = name;
gl->gl_lockref.count = 1;
gl->gl_state = LM_ST_UNLOCKED;
gl->gl_target = LM_ST_UNLOCKED;
gl->gl_demote_state = LM_ST_EXCLUSIVE;
- gl->gl_hash = hash;
gl->gl_ops = glops;
gl->gl_dstamp = ktime_set(0, 0);
preempt_disable();
@@ -769,22 +718,34 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
mapping->writeback_index = 0;
}
- spin_lock_bucket(hash);
- tmp = search_bucket(hash, &name);
- if (tmp) {
- spin_unlock_bucket(hash);
- kfree(gl->gl_lksb.sb_lvbptr);
- kmem_cache_free(cachep, gl);
- atomic_dec(&sdp->sd_glock_disposal);
- gl = tmp;
- } else {
- hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
- spin_unlock_bucket(hash);
+again:
+ ret = rhashtable_lookup_insert_fast(&gl_hash_table, &gl->gl_node,
+ ht_parms);
+ if (ret == 0) {
+ *glp = gl;
+ return 0;
}
- *glp = gl;
+ if (ret == -EEXIST) {
+ ret = 0;
+ tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
+ if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
+ if (++tries < 100) {
+ cond_resched();
+ goto again;
+ }
+ tmp = NULL;
+ ret = -ENOMEM;
+ }
+ } else {
+ WARN_ON_ONCE(ret);
+ }
+ kfree(gl->gl_lksb.sb_lvbptr);
+ kmem_cache_free(cachep, gl);
+ atomic_dec(&sdp->sd_glock_disposal);
+ *glp = tmp;
- return 0;
+ return ret;
}
/**
@@ -1460,31 +1421,24 @@ static struct shrinker glock_shrinker = {
*
*/
-static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
- unsigned int hash)
+static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl;
- struct hlist_bl_head *head = &gl_hash_table[hash];
- struct hlist_bl_node *pos;
+ struct rhash_head *pos, *next;
+ const struct bucket_table *tbl;
+ int i;
- rcu_read_lock();
- hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
- if ((gl->gl_name.ln_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref))
- examiner(gl);
+ tbl = rht_dereference_rcu(gl_hash_table.tbl, &gl_hash_table);
+ for (i = 0; i < tbl->size; i++) {
+ rht_for_each_entry_safe(gl, pos, next, tbl, i, gl_node) {
+ if ((gl->gl_name.ln_sbd == sdp) &&
+ lockref_get_not_dead(&gl->gl_lockref))
+ examiner(gl);
+ }
}
- rcu_read_unlock();
cond_resched();
}
-static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
-{
- unsigned x;
-
- for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
- examine_bucket(examiner, sdp, x);
-}
-
-
/**
* thaw_glock - thaw out a glock which has an unprocessed reply waiting
* @gl: The glock to thaw
@@ -1802,20 +1756,24 @@ static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
int __init gfs2_glock_init(void)
{
- unsigned i;
- for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
- INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
- }
+ int ret;
+
+ ret = rhashtable_init(&gl_hash_table, &ht_parms);
+ if (ret < 0)
+ return ret;
glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
WQ_HIGHPRI | WQ_FREEZABLE, 0);
- if (!glock_workqueue)
+ if (!glock_workqueue) {
+ rhashtable_destroy(&gl_hash_table);
return -ENOMEM;
+ }
gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
WQ_MEM_RECLAIM | WQ_FREEZABLE,
0);
if (!gfs2_delete_workqueue) {
destroy_workqueue(glock_workqueue);
+ rhashtable_destroy(&gl_hash_table);
return -ENOMEM;
}
@@ -1827,72 +1785,36 @@ int __init gfs2_glock_init(void)
void gfs2_glock_exit(void)
{
unregister_shrinker(&glock_shrinker);
+ rhashtable_destroy(&gl_hash_table);
destroy_workqueue(glock_workqueue);
destroy_workqueue(gfs2_delete_workqueue);
}
-static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
+static void gfs2_glock_iter_next(struct gfs2_glock_rht_iter *gi)
{
- return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
- struct gfs2_glock, gl_list);
-}
-
-static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
-{
- return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
- struct gfs2_glock, gl_list);
-}
-
-static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
-{
- struct gfs2_glock *gl;
-
do {
- gl = gi->gl;
- if (gl) {
- gi->gl = glock_hash_next(gl);
- gi->nhash++;
- } else {
- if (gi->hash >= GFS2_GL_HASH_SIZE) {
- rcu_read_unlock();
- return 1;
- }
- gi->gl = glock_hash_chain(gi->hash);
- gi->nhash = 0;
- }
- while (gi->gl == NULL) {
- gi->hash++;
- if (gi->hash >= GFS2_GL_HASH_SIZE) {
- rcu_read_unlock();
- return 1;
- }
- gi->gl = glock_hash_chain(gi->hash);
- gi->nhash = 0;
- }
+ gi->gl = rhashtable_walk_next(&gi->hti);
/* Skip entries for other sb and dead entries */
- } while (gi->sdp != gi->gl->gl_name.ln_sbd ||
- __lockref_is_dead(&gi->gl->gl_lockref));
-
- return 0;
+ } while ((gi->gl) && ((gi->sdp != gi->gl->gl_name.ln_sbd) ||
+ __lockref_is_dead(&gi->gl->gl_lockref)));
}
static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
{
- struct gfs2_glock_iter *gi = seq->private;
+ struct gfs2_glock_rht_iter *gi = seq->private;
loff_t n = *pos;
+ int ret;
if (gi->last_pos <= *pos)
- n = gi->nhash + (*pos - gi->last_pos);
- else
- gi->hash = 0;
+ n = (*pos - gi->last_pos);
- gi->nhash = 0;
- rcu_read_lock();
+ ret = rhashtable_walk_start(&gi->hti);
+ if (ret)
+ return NULL;
do {
- if (gfs2_glock_iter_next(gi))
- return NULL;
- } while (n--);
+ gfs2_glock_iter_next(gi);
+ } while (gi->gl && n--);
gi->last_pos = *pos;
return gi->gl;
@@ -1901,23 +1823,20 @@ static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
loff_t *pos)
{
- struct gfs2_glock_iter *gi = seq->private;
+ struct gfs2_glock_rht_iter *gi = seq->private;
(*pos)++;
gi->last_pos = *pos;
- if (gfs2_glock_iter_next(gi))
- return NULL;
-
+ gfs2_glock_iter_next(gi);
return gi->gl;
}
static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
{
- struct gfs2_glock_iter *gi = seq->private;
+ struct gfs2_glock_rht_iter *gi = seq->private;
- if (gi->gl)
- rcu_read_unlock();
gi->gl = NULL;
+ rhashtable_walk_stop(&gi->hti);
}
static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
@@ -1981,29 +1900,46 @@ static const struct seq_operations gfs2_sbstats_seq_ops = {
static int gfs2_glocks_open(struct inode *inode, struct file *file)
{
int ret = seq_open_private(file, &gfs2_glock_seq_ops,
- sizeof(struct gfs2_glock_iter));
+ sizeof(struct gfs2_glock_rht_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
- struct gfs2_glock_iter *gi = seq->private;
+ struct gfs2_glock_rht_iter *gi = seq->private;
+
gi->sdp = inode->i_private;
+ gi->last_pos = 0;
seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
if (seq->buf)
seq->size = GFS2_SEQ_GOODSIZE;
+ gi->gl = NULL;
+ ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);
}
return ret;
}
+static int gfs2_glocks_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *seq = file->private_data;
+ struct gfs2_glock_rht_iter *gi = seq->private;
+
+ gi->gl = NULL;
+ rhashtable_walk_exit(&gi->hti);
+ return seq_release_private(inode, file);
+}
+
static int gfs2_glstats_open(struct inode *inode, struct file *file)
{
int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
- sizeof(struct gfs2_glock_iter));
+ sizeof(struct gfs2_glock_rht_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
- struct gfs2_glock_iter *gi = seq->private;
+ struct gfs2_glock_rht_iter *gi = seq->private;
gi->sdp = inode->i_private;
+ gi->last_pos = 0;
seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
if (seq->buf)
seq->size = GFS2_SEQ_GOODSIZE;
+ gi->gl = NULL;
+ ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);
}
return ret;
}
@@ -2025,7 +1961,7 @@ static const struct file_operations gfs2_glocks_fops = {
.open = gfs2_glocks_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release_private,
+ .release = gfs2_glocks_release,
};
static const struct file_operations gfs2_glstats_fops = {
@@ -2033,7 +1969,7 @@ static const struct file_operations gfs2_glstats_fops = {
.open = gfs2_glstats_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release_private,
+ .release = gfs2_glocks_release,
};
static const struct file_operations gfs2_sbstats_fops = {
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 4de7853..0d63715 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -22,6 +22,7 @@
#include <linux/ktime.h>
#include <linux/percpu.h>
#include <linux/lockref.h>
+#include <linux/rhashtable.h>
#define DIO_WAIT 0x00000010
#define DIO_METADATA 0x00000020
@@ -342,7 +343,6 @@ struct gfs2_glock {
gl_req:2, /* State in last dlm request */
gl_reply:8; /* Last reply from the dlm */
- unsigned int gl_hash;
unsigned long gl_demote_time; /* time of first demote request */
long gl_hold_time;
struct list_head gl_holders;
@@ -368,7 +368,7 @@ struct gfs2_glock {
loff_t end;
} gl_vm;
};
- struct rcu_head gl_rcu;
+ struct rhash_head gl_node;
};
#define GFS2_MIN_LVB_SIZE 32 /* Min size of LVB that gfs2 supports */
--
2.1.0
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