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Subject[patch 29/33] Remove the global inode_hash_lock and replace it with per-hash-bucket locks. fs: inode per-bucket inode hash locks
Todo: should use bit spinlock in hlist_head pointer to save space.
---
fs/inode.c | 167 ++++++++++++++++++++++++++++++++-----------------------------
1 file changed, 90 insertions(+), 77 deletions(-)
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -76,7 +76,12 @@ static unsigned int i_hash_shift __read_

LIST_HEAD(inode_in_use);
LIST_HEAD(inode_unused);
-static struct hlist_head *inode_hashtable __read_mostly;
+
+struct inode_hash_bucket {
+ spinlock_t lock;
+ struct hlist_head head;
+};
+static struct inode_hash_bucket *inode_hashtable __read_mostly;

/*
* A simple spinlock to protect the list manipulations.
@@ -86,7 +91,6 @@ static struct hlist_head *inode_hashtabl
*/
DEFINE_SPINLOCK(sb_inode_list_lock);
DEFINE_SPINLOCK(wb_inode_list_lock);
-static DEFINE_SPINLOCK(inode_hash_lock);

/*
* iprune_mutex provides exclusion between the kswapd or try_to_free_pages
@@ -582,7 +586,7 @@ static void __wait_on_freeing_inode(stru
* add any additional branch in the common code.
*/
static struct inode *find_inode(struct super_block *sb,
- struct hlist_head *head,
+ struct inode_hash_bucket *b,
int (*test)(struct inode *, void *),
void *data)
{
@@ -590,12 +594,12 @@ static struct inode *find_inode(struct s
struct inode *inode = NULL;

repeat:
- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(inode, node, head, i_hash) {
+ spin_lock(&b->lock);
+ hlist_for_each_entry(inode, node, &b->head, i_hash) {
if (inode->i_sb != sb)
continue;
if (!spin_trylock(&inode->i_lock)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
goto repeat;
}
if (!test(inode, data)) {
@@ -603,13 +607,13 @@ repeat:
continue;
}
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
__wait_on_freeing_inode(inode);
goto repeat;
}
break;
}
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
return node ? inode : NULL;
}

@@ -618,30 +622,31 @@ repeat:
* iget_locked for details.
*/
static struct inode *find_inode_fast(struct super_block *sb,
- struct hlist_head *head, unsigned long ino)
+ struct inode_hash_bucket *b,
+ unsigned long ino)
{
struct hlist_node *node;
struct inode *inode = NULL;

repeat:
- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(inode, node, head, i_hash) {
+ spin_lock(&b->lock);
+ hlist_for_each_entry(inode, node, &b->head, i_hash) {
if (inode->i_ino != ino)
continue;
if (inode->i_sb != sb)
continue;
if (!spin_trylock(&inode->i_lock)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
goto repeat;
}
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
__wait_on_freeing_inode(inode);
goto repeat;
}
break;
}
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
return node ? inode : NULL;
}

@@ -656,7 +661,7 @@ static unsigned long hash(struct super_b
}

static inline void
-__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
+__inode_add_to_lists(struct super_block *sb, struct inode_hash_bucket *b,
struct inode *inode)
{
atomic_inc(&inodes_stat.nr_inodes);
@@ -665,10 +670,10 @@ __inode_add_to_lists(struct super_block
spin_lock(&wb_inode_list_lock);
list_add(&inode->i_list, &inode_in_use);
spin_unlock(&wb_inode_list_lock);
- if (head) {
- spin_lock(&inode_hash_lock);
- hlist_add_head(&inode->i_hash, head);
- spin_unlock(&inode_hash_lock);
+ if (b) {
+ spin_lock(&b->lock);
+ hlist_add_head(&inode->i_hash, &b->head);
+ spin_unlock(&b->lock);
}
}

@@ -686,11 +691,11 @@ __inode_add_to_lists(struct super_block
*/
void inode_add_to_lists(struct super_block *sb, struct inode *inode)
{
- struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, inode->i_ino);

spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
- __inode_add_to_lists(sb, head, inode);
+ __inode_add_to_lists(sb, b, inode);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL_GPL(inode_add_to_lists);
@@ -770,7 +775,7 @@ EXPORT_SYMBOL(unlock_new_inode);
* -- rmk@arm.uk.linux.org
*/
static struct inode *get_new_inode(struct super_block *sb,
- struct hlist_head *head,
+ struct inode_hash_bucket *b,
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *),
void *data)
@@ -782,7 +787,7 @@ static struct inode *get_new_inode(struc
struct inode *old;

/* We released the lock, so.. */
- old = find_inode(sb, head, test, data);
+ old = find_inode(sb, b, test, data);
if (!old) {
spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
@@ -790,7 +795,7 @@ static struct inode *get_new_inode(struc
goto set_failed;

inode->i_state = I_LOCK|I_NEW;
- __inode_add_to_lists(sb, head, inode);
+ __inode_add_to_lists(sb, b, inode);
spin_unlock(&inode->i_lock);

/* Return the locked inode with I_NEW set, the
@@ -824,7 +829,7 @@ set_failed:
* comment at iget_locked for details.
*/
static struct inode *get_new_inode_fast(struct super_block *sb,
- struct hlist_head *head, unsigned long ino)
+ struct inode_hash_bucket *b, unsigned long ino)
{
struct inode *inode;

@@ -833,13 +838,13 @@ static struct inode *get_new_inode_fast(
struct inode *old;

/* We released the lock, so.. */
- old = find_inode_fast(sb, head, ino);
+ old = find_inode_fast(sb, b, ino);
if (!old) {
spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
inode->i_ino = ino;
inode->i_state = I_LOCK|I_NEW;
- __inode_add_to_lists(sb, head, inode);
+ __inode_add_to_lists(sb, b, inode);
spin_unlock(&inode->i_lock);

/* Return the locked inode with I_NEW set, the
@@ -862,19 +867,20 @@ static struct inode *get_new_inode_fast(
return inode;
}

-static int test_inode_iunique(struct super_block * sb, struct hlist_head *head, unsigned long ino)
+static int test_inode_iunique(struct super_block *sb,
+ struct inode_hash_bucket *b, unsigned long ino)
{
struct hlist_node *node;
- struct inode * inode = NULL;
+ struct inode *inode = NULL;

- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(inode, node, head, i_hash) {
+ spin_lock(&b->lock);
+ hlist_for_each_entry(inode, node, &b->head, i_hash) {
if (inode->i_ino == ino && inode->i_sb == sb) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
return 0;
}
}
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
return 1;
}

@@ -901,7 +907,7 @@ ino_t iunique(struct super_block *sb, in
*/
static DEFINE_SPINLOCK(unique_lock);
static unsigned int counter;
- struct hlist_head *head;
+ struct inode_hash_bucket *b;
ino_t res;

spin_lock(&unique_lock);
@@ -909,8 +915,8 @@ ino_t iunique(struct super_block *sb, in
if (counter <= max_reserved)
counter = max_reserved + 1;
res = counter++;
- head = inode_hashtable + hash(sb, res);
- } while (!test_inode_iunique(sb, head, res));
+ b = inode_hashtable + hash(sb, res);
+ } while (!test_inode_iunique(sb, b, res));
spin_unlock(&unique_lock);

return res;
@@ -957,12 +963,13 @@ EXPORT_SYMBOL(igrab);
* Note, @test is called with the inode_lock held, so can't sleep.
*/
static struct inode *ifind(struct super_block *sb,
- struct hlist_head *head, int (*test)(struct inode *, void *),
+ struct inode_hash_bucket *b,
+ int (*test)(struct inode *, void *),
void *data, const int wait)
{
struct inode *inode;

- inode = find_inode(sb, head, test, data);
+ inode = find_inode(sb, b, test, data);
if (inode) {
__iget(inode);
spin_unlock(&inode->i_lock);
@@ -989,11 +996,12 @@ static struct inode *ifind(struct super_
* Otherwise NULL is returned.
*/
static struct inode *ifind_fast(struct super_block *sb,
- struct hlist_head *head, unsigned long ino)
+ struct inode_hash_bucket *b,
+ unsigned long ino)
{
struct inode *inode;

- inode = find_inode_fast(sb, head, ino);
+ inode = find_inode_fast(sb, b, ino);
if (inode) {
__iget(inode);
spin_unlock(&inode->i_lock);
@@ -1027,9 +1035,9 @@ static struct inode *ifind_fast(struct s
struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
{
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, hashval);

- return ifind(sb, head, test, data, 0);
+ return ifind(sb, b, test, data, 0);
}
EXPORT_SYMBOL(ilookup5_nowait);

@@ -1055,9 +1063,9 @@ EXPORT_SYMBOL(ilookup5_nowait);
struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
{
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, hashval);

- return ifind(sb, head, test, data, 1);
+ return ifind(sb, b, test, data, 1);
}
EXPORT_SYMBOL(ilookup5);

@@ -1077,9 +1085,9 @@ EXPORT_SYMBOL(ilookup5);
*/
struct inode *ilookup(struct super_block *sb, unsigned long ino)
{
- struct hlist_head *head = inode_hashtable + hash(sb, ino);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, ino);

- return ifind_fast(sb, head, ino);
+ return ifind_fast(sb, b, ino);
}
EXPORT_SYMBOL(ilookup);

@@ -1107,17 +1115,17 @@ struct inode *iget5_locked(struct super_
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *), void *data)
{
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, hashval);
struct inode *inode;

- inode = ifind(sb, head, test, data, 1);
+ inode = ifind(sb, b, test, data, 1);
if (inode)
return inode;
/*
* get_new_inode() will do the right thing, re-trying the search
* in case it had to block at any point.
*/
- return get_new_inode(sb, head, test, set, data);
+ return get_new_inode(sb, b, test, set, data);
}
EXPORT_SYMBOL(iget5_locked);

@@ -1138,17 +1146,17 @@ EXPORT_SYMBOL(iget5_locked);
*/
struct inode *iget_locked(struct super_block *sb, unsigned long ino)
{
- struct hlist_head *head = inode_hashtable + hash(sb, ino);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, ino);
struct inode *inode;

- inode = ifind_fast(sb, head, ino);
+ inode = ifind_fast(sb, b, ino);
if (inode)
return inode;
/*
* get_new_inode_fast() will do the right thing, re-trying the search
* in case it had to block at any point.
*/
- return get_new_inode_fast(sb, head, ino);
+ return get_new_inode_fast(sb, b, ino);
}
EXPORT_SYMBOL(iget_locked);

@@ -1156,7 +1164,7 @@ int insert_inode_locked(struct inode *in
{
struct super_block *sb = inode->i_sb;
ino_t ino = inode->i_ino;
- struct hlist_head *head = inode_hashtable + hash(sb, ino);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, ino);

inode->i_state |= I_LOCK|I_NEW;
while (1) {
@@ -1164,8 +1172,8 @@ int insert_inode_locked(struct inode *in
struct inode *old = NULL;

repeat:
- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(old, node, head, i_hash) {
+ spin_lock(&b->lock);
+ hlist_for_each_entry(old, node, &b->head, i_hash) {
if (old->i_ino != ino)
continue;
if (old->i_sb != sb)
@@ -1173,18 +1181,18 @@ repeat:
if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
continue;
if (!spin_trylock(&old->i_lock)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
goto repeat;
}
break;
}
if (likely(!node)) {
/* XXX: initialize inode->i_lock to locked? */
- hlist_add_head(&inode->i_hash, head);
- spin_unlock(&inode_hash_lock);
+ hlist_add_head(&inode->i_hash, &b->head);
+ spin_unlock(&b->lock);
return 0;
}
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
__iget(old);
spin_unlock(&old->i_lock);
wait_on_inode(old);
@@ -1201,7 +1209,7 @@ int insert_inode_locked4(struct inode *i
int (*test)(struct inode *, void *), void *data)
{
struct super_block *sb = inode->i_sb;
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode_hash_bucket *b = inode_hashtable + hash(sb, hashval);

inode->i_state |= I_LOCK|I_NEW;

@@ -1210,8 +1218,8 @@ int insert_inode_locked4(struct inode *i
struct inode *old = NULL;

repeat:
- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(old, node, head, i_hash) {
+ spin_lock(&b->lock);
+ hlist_for_each_entry(old, node, &b->head, i_hash) {
if (old->i_sb != sb)
continue;
if (!test(old, data))
@@ -1219,18 +1227,18 @@ repeat:
if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
continue;
if (!spin_trylock(&old->i_lock)) {
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
goto repeat;
}
break;
}
if (likely(!node)) {
/* XXX: initialize inode->i_lock to locked? */
- hlist_add_head(&inode->i_hash, head);
- spin_unlock(&inode_hash_lock);
+ hlist_add_head(&inode->i_hash, &b->head);
+ spin_unlock(&b->lock);
return 0;
}
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
__iget(old);
spin_unlock(&old->i_lock);
wait_on_inode(old);
@@ -1253,12 +1261,12 @@ EXPORT_SYMBOL(insert_inode_locked4);
*/
void __insert_inode_hash(struct inode *inode, unsigned long hashval)
{
- struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
+ struct inode_hash_bucket *b = inode_hashtable + hash(inode->i_sb, hashval);

spin_lock(&inode->i_lock);
- spin_lock(&inode_hash_lock);
- hlist_add_head(&inode->i_hash, head);
- spin_unlock(&inode_hash_lock);
+ spin_lock(&b->lock);
+ hlist_add_head(&inode->i_hash, &b->head);
+ spin_unlock(&b->lock);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(__insert_inode_hash);
@@ -1272,9 +1280,10 @@ EXPORT_SYMBOL(__insert_inode_hash);
*/
void __remove_inode_hash(struct inode *inode)
{
- spin_lock(&inode_hash_lock);
+ struct inode_hash_bucket *b = inode_hashtable + hash(inode->i_sb, inode->i_ino);
+ spin_lock(&b->lock);
hlist_del_init(&inode->i_hash);
- spin_unlock(&inode_hash_lock);
+ spin_unlock(&b->lock);
}

/**
@@ -1663,7 +1672,7 @@ void __init inode_init_early(void)

inode_hashtable =
alloc_large_system_hash("Inode-cache",
- sizeof(struct hlist_head),
+ sizeof(struct inode_hash_bucket),
ihash_entries,
14,
HASH_EARLY,
@@ -1671,8 +1680,10 @@ void __init inode_init_early(void)
&i_hash_mask,
0);

- for (loop = 0; loop < (1 << i_hash_shift); loop++)
- INIT_HLIST_HEAD(&inode_hashtable[loop]);
+ for (loop = 0; loop < (1 << i_hash_shift); loop++) {
+ spin_lock_init(&inode_hashtable[loop].lock);
+ INIT_HLIST_HEAD(&inode_hashtable[loop].head);
+ }
}

void __init inode_init(void)
@@ -1702,8 +1713,10 @@ void __init inode_init(void)
&i_hash_mask,
0);

- for (loop = 0; loop < (1 << i_hash_shift); loop++)
- INIT_HLIST_HEAD(&inode_hashtable[loop]);
+ for (loop = 0; loop < (1 << i_hash_shift); loop++) {
+ spin_lock_init(&inode_hashtable[loop].lock);
+ INIT_HLIST_HEAD(&inode_hashtable[loop].head);
+ }
}

void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)



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