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fs: dcache per-bucket dcache hash locking

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We can turn the dcache hash locking from a global dcache_hash_lock into
per-bucket locking.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin 2011-01-07 17:50:05 +11:00
parent 626d607435
commit ceb5bdc2d2
4 changed files with 89 additions and 53 deletions
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133
fs/dcache.c
View file

@ -33,14 +33,18 @@
#include <linux/bootmem.h> #include <linux/bootmem.h>
#include <linux/fs_struct.h> #include <linux/fs_struct.h>
#include <linux/hardirq.h> #include <linux/hardirq.h>
#include <linux/bit_spinlock.h>
#include <linux/rculist_bl.h>
#include "internal.h" #include "internal.h"
/* /*
* Usage: * Usage:
* dcache_inode_lock protects: * dcache_inode_lock protects:
* - i_dentry, d_alias, d_inode * - i_dentry, d_alias, d_inode
* dcache_hash_lock protects: * dcache_hash_bucket lock protects:
* - the dcache hash table, s_anon lists * - the dcache hash table
* s_anon bl list spinlock protects:
* - the s_anon list (see __d_drop)
* dcache_lru_lock protects: * dcache_lru_lock protects:
* - the dcache lru lists and counters * - the dcache lru lists and counters
* d_lock protects: * d_lock protects:
@ -57,7 +61,8 @@
* dcache_inode_lock * dcache_inode_lock
* dentry->d_lock * dentry->d_lock
* dcache_lru_lock * dcache_lru_lock
* dcache_hash_lock * dcache_hash_bucket lock
* s_anon lock
* *
* If there is an ancestor relationship: * If there is an ancestor relationship:
* dentry->d_parent->...->d_parent->d_lock * dentry->d_parent->...->d_parent->d_lock
@ -74,7 +79,6 @@ int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock); __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
@ -96,7 +100,29 @@ static struct kmem_cache *dentry_cache __read_mostly;
static unsigned int d_hash_mask __read_mostly; static unsigned int d_hash_mask __read_mostly;
static unsigned int d_hash_shift __read_mostly; static unsigned int d_hash_shift __read_mostly;
static struct hlist_head *dentry_hashtable __read_mostly;
struct dcache_hash_bucket {
struct hlist_bl_head head;
};
static struct dcache_hash_bucket *dentry_hashtable __read_mostly;
static inline struct dcache_hash_bucket *d_hash(struct dentry *parent,
unsigned long hash)
{
hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
return dentry_hashtable + (hash & D_HASHMASK);
}
static inline void spin_lock_bucket(struct dcache_hash_bucket *b)
{
bit_spin_lock(0, (unsigned long *)&b->head.first);
}
static inline void spin_unlock_bucket(struct dcache_hash_bucket *b)
{
__bit_spin_unlock(0, (unsigned long *)&b->head.first);
}
/* Statistics gathering. */ /* Statistics gathering. */
struct dentry_stat_t dentry_stat = { struct dentry_stat_t dentry_stat = {
@ -144,7 +170,7 @@ static void d_free(struct dentry *dentry)
dentry->d_op->d_release(dentry); dentry->d_op->d_release(dentry);
/* if dentry was never inserted into hash, immediate free is OK */ /* if dentry was never inserted into hash, immediate free is OK */
if (hlist_unhashed(&dentry->d_hash)) if (hlist_bl_unhashed(&dentry->d_hash))
__d_free(&dentry->d_u.d_rcu); __d_free(&dentry->d_u.d_rcu);
else else
call_rcu(&dentry->d_u.d_rcu, __d_free); call_rcu(&dentry->d_u.d_rcu, __d_free);
@ -302,11 +328,27 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
void __d_drop(struct dentry *dentry) void __d_drop(struct dentry *dentry)
{ {
if (!(dentry->d_flags & DCACHE_UNHASHED)) { if (!(dentry->d_flags & DCACHE_UNHASHED)) {
dentry->d_flags |= DCACHE_UNHASHED; if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) {
spin_lock(&dcache_hash_lock); bit_spin_lock(0,
hlist_del_rcu(&dentry->d_hash); (unsigned long *)&dentry->d_sb->s_anon.first);
spin_unlock(&dcache_hash_lock); dentry->d_flags |= DCACHE_UNHASHED;
dentry_rcuwalk_barrier(dentry); hlist_bl_del_init(&dentry->d_hash);
__bit_spin_unlock(0,
(unsigned long *)&dentry->d_sb->s_anon.first);
} else {
struct dcache_hash_bucket *b;
b = d_hash(dentry->d_parent, dentry->d_name.hash);
spin_lock_bucket(b);
/*
* We may not actually need to put DCACHE_UNHASHED
* manipulations under the hash lock, but follow
* the principle of least surprise.
*/
dentry->d_flags |= DCACHE_UNHASHED;
hlist_bl_del_rcu(&dentry->d_hash);
spin_unlock_bucket(b);
dentry_rcuwalk_barrier(dentry);
}
} }
} }
EXPORT_SYMBOL(__d_drop); EXPORT_SYMBOL(__d_drop);
@ -961,8 +1003,8 @@ void shrink_dcache_for_umount(struct super_block *sb)
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
shrink_dcache_for_umount_subtree(dentry); shrink_dcache_for_umount_subtree(dentry);
while (!hlist_empty(&sb->s_anon)) { while (!hlist_bl_empty(&sb->s_anon)) {
dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
shrink_dcache_for_umount_subtree(dentry); shrink_dcache_for_umount_subtree(dentry);
} }
} }
@ -1263,7 +1305,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
dentry->d_sb = NULL; dentry->d_sb = NULL;
dentry->d_op = NULL; dentry->d_op = NULL;
dentry->d_fsdata = NULL; dentry->d_fsdata = NULL;
INIT_HLIST_NODE(&dentry->d_hash); INIT_HLIST_BL_NODE(&dentry->d_hash);
INIT_LIST_HEAD(&dentry->d_lru); INIT_LIST_HEAD(&dentry->d_lru);
INIT_LIST_HEAD(&dentry->d_subdirs); INIT_LIST_HEAD(&dentry->d_subdirs);
INIT_LIST_HEAD(&dentry->d_alias); INIT_LIST_HEAD(&dentry->d_alias);
@ -1459,14 +1501,6 @@ struct dentry * d_alloc_root(struct inode * root_inode)
} }
EXPORT_SYMBOL(d_alloc_root); EXPORT_SYMBOL(d_alloc_root);
static inline struct hlist_head *d_hash(struct dentry *parent,
unsigned long hash)
{
hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
return dentry_hashtable + (hash & D_HASHMASK);
}
/** /**
* d_obtain_alias - find or allocate a dentry for a given inode * d_obtain_alias - find or allocate a dentry for a given inode
* @inode: inode to allocate the dentry for * @inode: inode to allocate the dentry for
@ -1521,11 +1555,11 @@ struct dentry *d_obtain_alias(struct inode *inode)
tmp->d_sb = inode->i_sb; tmp->d_sb = inode->i_sb;
tmp->d_inode = inode; tmp->d_inode = inode;
tmp->d_flags |= DCACHE_DISCONNECTED; tmp->d_flags |= DCACHE_DISCONNECTED;
tmp->d_flags &= ~DCACHE_UNHASHED;
list_add(&tmp->d_alias, &inode->i_dentry); list_add(&tmp->d_alias, &inode->i_dentry);
spin_lock(&dcache_hash_lock); bit_spin_lock(0, (unsigned long *)&tmp->d_sb->s_anon.first);
hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); tmp->d_flags &= ~DCACHE_UNHASHED;
spin_unlock(&dcache_hash_lock); hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
__bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon.first);
spin_unlock(&tmp->d_lock); spin_unlock(&tmp->d_lock);
spin_unlock(&dcache_inode_lock); spin_unlock(&dcache_inode_lock);
@ -1567,7 +1601,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
d_move(new, dentry); d_move(new, dentry);
iput(inode); iput(inode);
} else { } else {
/* already taking dcache_inode_lock, so d_add() by hand */ /* already got dcache_inode_lock, so d_add() by hand */
__d_instantiate(dentry, inode); __d_instantiate(dentry, inode);
spin_unlock(&dcache_inode_lock); spin_unlock(&dcache_inode_lock);
security_d_instantiate(dentry, inode); security_d_instantiate(dentry, inode);
@ -1702,8 +1736,8 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
unsigned int len = name->len; unsigned int len = name->len;
unsigned int hash = name->hash; unsigned int hash = name->hash;
const unsigned char *str = name->name; const unsigned char *str = name->name;
struct hlist_head *head = d_hash(parent, hash); struct dcache_hash_bucket *b = d_hash(parent, hash);
struct hlist_node *node; struct hlist_bl_node *node;
struct dentry *dentry; struct dentry *dentry;
/* /*
@ -1726,7 +1760,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
* *
* See Documentation/vfs/dcache-locking.txt for more details. * See Documentation/vfs/dcache-locking.txt for more details.
*/ */
hlist_for_each_entry_rcu(dentry, node, head, d_hash) { hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) {
struct inode *i; struct inode *i;
const char *tname; const char *tname;
int tlen; int tlen;
@ -1820,8 +1854,8 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
unsigned int len = name->len; unsigned int len = name->len;
unsigned int hash = name->hash; unsigned int hash = name->hash;
const unsigned char *str = name->name; const unsigned char *str = name->name;
struct hlist_head *head = d_hash(parent,hash); struct dcache_hash_bucket *b = d_hash(parent, hash);
struct hlist_node *node; struct hlist_bl_node *node;
struct dentry *found = NULL; struct dentry *found = NULL;
struct dentry *dentry; struct dentry *dentry;
@ -1847,7 +1881,7 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
*/ */
rcu_read_lock(); rcu_read_lock();
hlist_for_each_entry_rcu(dentry, node, head, d_hash) { hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) {
const char *tname; const char *tname;
int tlen; int tlen;
@ -1998,11 +2032,13 @@ again:
} }
EXPORT_SYMBOL(d_delete); EXPORT_SYMBOL(d_delete);
static void __d_rehash(struct dentry * entry, struct hlist_head *list) static void __d_rehash(struct dentry * entry, struct dcache_hash_bucket *b)
{ {
BUG_ON(!d_unhashed(entry));
spin_lock_bucket(b);
entry->d_flags &= ~DCACHE_UNHASHED; entry->d_flags &= ~DCACHE_UNHASHED;
hlist_add_head_rcu(&entry->d_hash, list); hlist_bl_add_head_rcu(&entry->d_hash, &b->head);
spin_unlock_bucket(b);
} }
static void _d_rehash(struct dentry * entry) static void _d_rehash(struct dentry * entry)
@ -2020,9 +2056,7 @@ static void _d_rehash(struct dentry * entry)
void d_rehash(struct dentry * entry) void d_rehash(struct dentry * entry)
{ {
spin_lock(&entry->d_lock); spin_lock(&entry->d_lock);
spin_lock(&dcache_hash_lock);
_d_rehash(entry); _d_rehash(entry);
spin_unlock(&dcache_hash_lock);
spin_unlock(&entry->d_lock); spin_unlock(&entry->d_lock);
} }
EXPORT_SYMBOL(d_rehash); EXPORT_SYMBOL(d_rehash);
@ -2165,15 +2199,16 @@ void d_move(struct dentry * dentry, struct dentry * target)
write_seqcount_begin(&dentry->d_seq); write_seqcount_begin(&dentry->d_seq);
write_seqcount_begin(&target->d_seq); write_seqcount_begin(&target->d_seq);
/* Move the dentry to the target hash queue, if on different bucket */ /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
spin_lock(&dcache_hash_lock);
if (!d_unhashed(dentry)) /*
hlist_del_rcu(&dentry->d_hash); * Move the dentry to the target hash queue. Don't bother checking
* for the same hash queue because of how unlikely it is.
*/
__d_drop(dentry);
__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
spin_unlock(&dcache_hash_lock);
/* Unhash the target: dput() will then get rid of it */ /* Unhash the target: dput() will then get rid of it */
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
__d_drop(target); __d_drop(target);
list_del(&dentry->d_u.d_child); list_del(&dentry->d_u.d_child);
@ -2369,9 +2404,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
spin_lock(&actual->d_lock); spin_lock(&actual->d_lock);
found: found:
spin_lock(&dcache_hash_lock);
_d_rehash(actual); _d_rehash(actual);
spin_unlock(&dcache_hash_lock);
spin_unlock(&actual->d_lock); spin_unlock(&actual->d_lock);
spin_unlock(&dcache_inode_lock); spin_unlock(&dcache_inode_lock);
out_nolock: out_nolock:
@ -2953,7 +2986,7 @@ static void __init dcache_init_early(void)
dentry_hashtable = dentry_hashtable =
alloc_large_system_hash("Dentry cache", alloc_large_system_hash("Dentry cache",
sizeof(struct hlist_head), sizeof(struct dcache_hash_bucket),
dhash_entries, dhash_entries,
13, 13,
HASH_EARLY, HASH_EARLY,
@ -2962,7 +2995,7 @@ static void __init dcache_init_early(void)
0); 0);
for (loop = 0; loop < (1 << d_hash_shift); loop++) for (loop = 0; loop < (1 << d_hash_shift); loop++)
INIT_HLIST_HEAD(&dentry_hashtable[loop]); INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head);
} }
static void __init dcache_init(void) static void __init dcache_init(void)
@ -2985,7 +3018,7 @@ static void __init dcache_init(void)
dentry_hashtable = dentry_hashtable =
alloc_large_system_hash("Dentry cache", alloc_large_system_hash("Dentry cache",
sizeof(struct hlist_head), sizeof(struct dcache_hash_bucket),
dhash_entries, dhash_entries,
13, 13,
0, 0,
@ -2994,7 +3027,7 @@ static void __init dcache_init(void)
0); 0);
for (loop = 0; loop < (1 << d_hash_shift); loop++) for (loop = 0; loop < (1 << d_hash_shift); loop++)
INIT_HLIST_HEAD(&dentry_hashtable[loop]); INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head);
} }
/* SLAB cache for __getname() consumers */ /* SLAB cache for __getname() consumers */

3
fs/super.c
View file

@ -30,6 +30,7 @@
#include <linux/idr.h> #include <linux/idr.h>
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/backing-dev.h> #include <linux/backing-dev.h>
#include <linux/rculist_bl.h>
#include "internal.h" #include "internal.h"
@ -71,7 +72,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
INIT_LIST_HEAD(&s->s_files); INIT_LIST_HEAD(&s->s_files);
#endif #endif
INIT_LIST_HEAD(&s->s_instances); INIT_LIST_HEAD(&s->s_instances);
INIT_HLIST_HEAD(&s->s_anon); INIT_HLIST_BL_HEAD(&s->s_anon);
INIT_LIST_HEAD(&s->s_inodes); INIT_LIST_HEAD(&s->s_inodes);
INIT_LIST_HEAD(&s->s_dentry_lru); INIT_LIST_HEAD(&s->s_dentry_lru);
init_rwsem(&s->s_umount); init_rwsem(&s->s_umount);

3
include/linux/dcache.h
View file

@ -4,6 +4,7 @@
#include <asm/atomic.h> #include <asm/atomic.h>
#include <linux/list.h> #include <linux/list.h>
#include <linux/rculist.h> #include <linux/rculist.h>
#include <linux/rculist_bl.h>
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/seqlock.h> #include <linux/seqlock.h>
#include <linux/cache.h> #include <linux/cache.h>
@ -95,7 +96,7 @@ struct dentry {
/* RCU lookup touched fields */ /* RCU lookup touched fields */
unsigned int d_flags; /* protected by d_lock */ unsigned int d_flags; /* protected by d_lock */
seqcount_t d_seq; /* per dentry seqlock */ seqcount_t d_seq; /* per dentry seqlock */
struct hlist_node d_hash; /* lookup hash list */ struct hlist_bl_node d_hash; /* lookup hash list */
struct dentry *d_parent; /* parent directory */ struct dentry *d_parent; /* parent directory */
struct qstr d_name; struct qstr d_name;
struct inode *d_inode; /* Where the name belongs to - NULL is struct inode *d_inode; /* Where the name belongs to - NULL is

3
include/linux/fs.h
View file

@ -392,6 +392,7 @@ struct inodes_stat_t {
#include <linux/capability.h> #include <linux/capability.h>
#include <linux/semaphore.h> #include <linux/semaphore.h>
#include <linux/fiemap.h> #include <linux/fiemap.h>
#include <linux/rculist_bl.h>
#include <asm/atomic.h> #include <asm/atomic.h>
#include <asm/byteorder.h> #include <asm/byteorder.h>
@ -1377,7 +1378,7 @@ struct super_block {
const struct xattr_handler **s_xattr; const struct xattr_handler **s_xattr;
struct list_head s_inodes; /* all inodes */ struct list_head s_inodes; /* all inodes */
struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */ struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
struct list_head __percpu *s_files; struct list_head __percpu *s_files;
#else #else