[patch 39/52] fs: icache rcu walk for i_sb_list

npiggin
2010-06-24T03:16:54Z

[-- Attachment #1: fs-inode_lock-scale-11.patch --]
[-- Type: text/plain, Size: 10245 bytes --]

This enables locking to be reduced and ordering simplified.

Signed-off-by: Nick Piggin <npiggin@suse.de>
---
fs/drop_caches.c | 10 ++++----
fs/inode.c | 53 +++++++++++++++-----------------------------
fs/notify/inode_mark.c | 10 --------
fs/notify/inotify/inotify.c | 10 --------
fs/quota/dquot.c | 16 ++++++-------
5 files changed, 32 insertions(+), 67 deletions(-)

Index: linux-2.6/fs/drop_caches.c
===================================================================
--- linux-2.6.orig/fs/drop_caches.c
+++ linux-2.6/fs/drop_caches.c
@@ -16,8 +16,8 @@ static void drop_pagecache_sb(struct sup
{
struct inode *inode, *toput_inode = NULL;

- spin_lock(&sb_inode_list_lock);
- list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)
|| inode->i_mapping->nrpages == 0) {
@@ -26,13 +26,13 @@ static void drop_pagecache_sb(struct sup
}
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&sb_inode_list_lock);
+ rcu_read_unlock();
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
- spin_lock(&sb_inode_list_lock);
+ rcu_read_lock();
}
- spin_unlock(&sb_inode_list_lock);
+ rcu_read_unlock();
iput(toput_inode);
}

Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -44,10 +44,10 @@
*
* Ordering:
* inode_lock
- * sb_inode_list_lock
- * inode->i_lock
- * wb_inode_list_lock
- * inode_hash_bucket lock
+ * inode->i_lock
+ * sb_inode_list_lock
+ * wb_inode_list_lock
+ * inode_hash_bucket lock
*/
/*
* This is needed for the following functions:
@@ -379,12 +379,12 @@ static void dispose_list(struct list_hea
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);

- spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
__remove_inode_hash(inode);
- list_del_init(&inode->i_sb_list);
- spin_unlock(&inode->i_lock);
+ spin_lock(&sb_inode_list_lock);
+ list_del_rcu(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
+ spin_unlock(&inode->i_lock);

wake_up_inode(inode);
destroy_inode(inode);
@@ -406,14 +406,6 @@ static int invalidate_list(struct list_h
struct list_head *tmp = next;
struct inode *inode;

- /*
- * We can reschedule here without worrying about the list's
- * consistency because the per-sb list of inodes must not
- * change during umount anymore, and because iprune_sem keeps
- * shrink_icache_memory() away.
- */
- cond_resched_lock(&sb_inode_list_lock);
-
next = next->next;
if (tmp == head)
break;
@@ -456,12 +448,17 @@ int invalidate_inodes(struct super_block
int busy;
LIST_HEAD(throw_away);

+ /*
+ * Don't need to worry about the list's consistency because the per-sb
+ * list of inodes must not change during umount anymore, and because
+ * iprune_sem keeps shrink_icache_memory() away.
+ */
down_write(&iprune_sem);
- spin_lock(&sb_inode_list_lock);
+// spin_lock(&sb_inode_list_lock); XXX: is this safe?
inotify_unmount_inodes(&sb->s_inodes);
fsnotify_unmount_inodes(&sb->s_inodes);
busy = invalidate_list(&sb->s_inodes, &throw_away);
- spin_unlock(&sb_inode_list_lock);
+// spin_unlock(&sb_inode_list_lock);

dispose_list(&throw_away);
up_write(&iprune_sem);
@@ -665,7 +662,8 @@ __inode_add_to_lists(struct super_block
struct inode *inode)
{
atomic_inc(&inodes_stat.nr_inodes);
- list_add(&inode->i_sb_list, &sb->s_inodes);
+ spin_lock(&sb_inode_list_lock);
+ list_add_rcu(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
if (b) {
spin_lock_bucket(b);
@@ -690,7 +688,6 @@ void inode_add_to_lists(struct super_blo
{
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, b, inode);
spin_unlock(&inode->i_lock);
@@ -722,7 +719,6 @@ struct inode *new_inode(struct super_blo
inode = alloc_inode(sb);
if (inode) {
/* XXX: init as locked for speedup */
- spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
inode->i_ino = atomic_inc_return(&last_ino);
inode->i_state = 0;
@@ -789,7 +785,6 @@ static struct inode *get_new_inode(struc
/* We released the lock, so.. */
old = find_inode(sb, b, test, data);
if (!old) {
- spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
if (set(inode, data))
goto set_failed;
@@ -819,7 +814,6 @@ static struct inode *get_new_inode(struc

set_failed:
spin_unlock(&inode->i_lock);
- spin_unlock(&sb_inode_list_lock);
destroy_inode(inode);
return NULL;
}
@@ -840,7 +834,6 @@ static struct inode *get_new_inode_fast(
/* We released the lock, so.. */
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_NEW;
@@ -1320,7 +1313,8 @@ void generic_delete_inode(struct inode *
if (!inode->i_state)
atomic_dec(&inodes_stat.nr_unused);
}
- list_del_init(&inode->i_sb_list);
+ spin_lock(&sb_inode_list_lock);
+ list_del_rcu(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
@@ -1377,15 +1371,12 @@ int generic_detach_inode(struct inode *i
atomic_inc(&inodes_stat.nr_unused);
}
spin_unlock(&inode->i_lock);
- spin_unlock(&sb_inode_list_lock);
return 0;
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_WILL_FREE;
spin_unlock(&inode->i_lock);
- spin_unlock(&sb_inode_list_lock);
write_inode_now(inode, 1);
- spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
@@ -1398,7 +1389,8 @@ int generic_detach_inode(struct inode *i
if (!inode->i_state)
atomic_dec(&inodes_stat.nr_unused);
}
- list_del_init(&inode->i_sb_list);
+ spin_lock(&sb_inode_list_lock);
+ list_del_rcu(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
@@ -1468,19 +1460,12 @@ void iput(struct inode *inode)
if (inode) {
BUG_ON(inode->i_state == I_CLEAR);

-retry:
spin_lock(&inode->i_lock);
- if (inode->i_count == 1) {
- if (!spin_trylock(&sb_inode_list_lock)) {
- spin_unlock(&inode->i_lock);
- goto retry;
- }
- inode->i_count--;
+ inode->i_count--;
+ if (inode->i_count == 0)
iput_final(inode);
- } else {
- inode->i_count--;
+ else
spin_unlock(&inode->i_lock);
- }
}
}
EXPORT_SYMBOL(iput);
Index: linux-2.6/fs/notify/inode_mark.c
===================================================================
--- linux-2.6.orig/fs/notify/inode_mark.c
+++ linux-2.6/fs/notify/inode_mark.c
@@ -412,14 +412,6 @@ void fsnotify_unmount_inodes(struct list
spin_unlock(&next_i->i_lock);
}

- /*
- * We can safely drop inode_lock here because we hold
- * references on both inode and next_i. Also no new inodes
- * will be added since the umount has begun. Finally,
- * iprune_mutex keeps shrink_icache_memory() away.
- */
- spin_unlock(&sb_inode_list_lock);
-
if (need_iput_tmp)
iput(need_iput_tmp);

@@ -429,7 +421,5 @@ void fsnotify_unmount_inodes(struct list
fsnotify_inode_delete(inode);

iput(inode);
-
- spin_lock(&sb_inode_list_lock);
}
}
Index: linux-2.6/fs/notify/inotify/inotify.c
===================================================================
--- linux-2.6.orig/fs/notify/inotify/inotify.c
+++ linux-2.6/fs/notify/inotify/inotify.c
@@ -434,14 +434,6 @@ void inotify_unmount_inodes(struct list_
spin_unlock(&next_i->i_lock);
}

- /*
- * We can safely drop inode_lock here because we hold
- * references on both inode and next_i. Also no new inodes
- * will be added since the umount has begun. Finally,
- * iprune_mutex keeps shrink_icache_memory() away.
- */
- spin_unlock(&sb_inode_list_lock);
-
if (need_iput_tmp)
iput(need_iput_tmp);

@@ -459,8 +451,6 @@ void inotify_unmount_inodes(struct list_
}
mutex_unlock(&inode->inotify_mutex);
iput(inode);
-
- spin_lock(&sb_inode_list_lock);
}
}
EXPORT_SYMBOL_GPL(inotify_unmount_inodes);
Index: linux-2.6/fs/quota/dquot.c
===================================================================
--- linux-2.6.orig/fs/quota/dquot.c
+++ linux-2.6/fs/quota/dquot.c
@@ -883,8 +883,8 @@ static void add_dquot_ref(struct super_b
int reserved = 0;
#endif

- spin_lock(&sb_inode_list_lock);
- list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) {
spin_unlock(&inode->i_lock);
@@ -905,7 +905,7 @@ static void add_dquot_ref(struct super_b

__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&sb_inode_list_lock);
+ rcu_read_unlock();

iput(old_inode);
__dquot_initialize(inode, type);
@@ -915,9 +915,9 @@ static void add_dquot_ref(struct super_b
* reference and we cannot iput it under inode_lock. So we
* keep the reference and iput it later. */
old_inode = inode;
- spin_lock(&sb_inode_list_lock);
+ rcu_read_lock();
}
- spin_unlock(&sb_inode_list_lock);
+ rcu_read_unlock();
iput(old_inode);

#ifdef CONFIG_QUOTA_DEBUG
@@ -995,8 +995,8 @@ static void remove_dquot_ref(struct supe
{
struct inode *inode;

- spin_lock(&sb_inode_list_lock);
- list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(inode, &sb->s_inodes, i_sb_list) {
/*
* We have to scan also I_NEW inodes because they can already
* have quota pointer initialized. Luckily, we need to touch
@@ -1006,7 +1006,7 @@ static void remove_dquot_ref(struct supe
if (!IS_NOQUOTA(inode))
remove_inode_dquot_ref(inode, type, tofree_head);
}
- spin_unlock(&sb_inode_list_lock);
+ rcu_read_unlock();
}

/* Gather all references from inodes and drop them */