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Subject[patch 30/33] fs: inode lazy lru
Impelemnt lazy inode lru similarly to dcache. This should reduce inode list
lock acquisition (todo: measure).
---
fs/fs-writeback.c | 2 -
fs/inode.c | 61 +++++++++++++++++++---------------------------
include/linux/fs.h | 7 ++++-
include/linux/writeback.h | 1
4 files changed, 33 insertions(+), 38 deletions(-)
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -74,7 +74,6 @@ static unsigned int i_hash_shift __read_
* allowing for low-overhead inode sync() operations.
*/

-LIST_HEAD(inode_in_use);
LIST_HEAD(inode_unused);

struct inode_hash_bucket {
@@ -273,6 +272,7 @@ void inode_init_once(struct inode *inode
INIT_HLIST_NODE(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_dentry);
INIT_LIST_HEAD(&inode->i_devices);
+ INIT_LIST_HEAD(&inode->i_list);
INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
spin_lock_init(&inode->i_data.tree_lock);
spin_lock_init(&inode->i_data.i_mmap_lock);
@@ -298,24 +298,6 @@ static void init_once(void *foo)
inode_init_once(inode);
}

-/*
- * inode_lock must be held
- */
-void __iget(struct inode *inode)
-{
- assert_spin_locked(&inode->i_lock);
- inode->i_count++;
- if (inode->i_count > 1)
- return;
-
- if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
- spin_lock(&wb_inode_list_lock);
- list_move(&inode->i_list, &inode_in_use);
- spin_unlock(&wb_inode_list_lock);
- }
- atomic_dec(&inodes_stat.nr_unused);
-}
-
/**
* clear_inode - clear an inode
* @inode: inode to clear
@@ -359,7 +341,7 @@ static void dispose_list(struct list_hea
struct inode *inode;

inode = list_first_entry(head, struct inode, i_list);
- list_del(&inode->i_list);
+ list_del_init(&inode->i_list);

if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
@@ -412,11 +394,12 @@ static int invalidate_list(struct list_h
invalidate_inode_buffers(inode);
if (!inode->i_count) {
spin_lock(&wb_inode_list_lock);
- list_move(&inode->i_list, dispose);
+ list_del(&inode->i_list);
spin_unlock(&wb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
+ list_add(&inode->i_list, dispose);
count++;
continue;
}
@@ -503,7 +486,13 @@ again:
spin_unlock(&wb_inode_list_lock);
goto again;
}
- if (inode->i_state || inode->i_count) {
+ if (inode->i_count) {
+ list_del_init(&inode->i_list);
+ spin_unlock(&inode->i_lock);
+ atomic_dec(&inodes_stat.nr_unused);
+ continue;
+ }
+ if (inode->i_state) {
list_move(&inode->i_list, &inode_unused);
spin_unlock(&inode->i_lock);
continue;
@@ -519,6 +508,7 @@ again:
again2:
spin_lock(&wb_inode_list_lock);

+ /* XXX: may no longer work well */
if (inode != list_entry(inode_unused.next,
struct inode, i_list))
continue; /* wrong inode or list_empty */
@@ -667,9 +657,6 @@ __inode_add_to_lists(struct super_block
atomic_inc(&inodes_stat.nr_inodes);
list_add(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
- spin_lock(&wb_inode_list_lock);
- list_add(&inode->i_list, &inode_in_use);
- spin_unlock(&wb_inode_list_lock);
if (b) {
spin_lock(&b->lock);
hlist_add_head(&inode->i_hash, &b->head);
@@ -1316,9 +1303,11 @@ void generic_delete_inode(struct inode *
{
const struct super_operations *op = inode->i_sb->s_op;

- spin_lock(&wb_inode_list_lock);
- list_del_init(&inode->i_list);
- spin_unlock(&wb_inode_list_lock);
+ if (!list_empty(&inode->i_list)) {
+ spin_lock(&wb_inode_list_lock);
+ list_del_init(&inode->i_list);
+ spin_unlock(&wb_inode_list_lock);
+ }
list_del_init(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
@@ -1355,12 +1344,12 @@ static void generic_forget_inode(struct
struct super_block *sb = inode->i_sb;

if (!hlist_unhashed(&inode->i_hash)) {
- if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
+ if (list_empty(&inode->i_list)) {
spin_lock(&wb_inode_list_lock);
- list_move(&inode->i_list, &inode_unused);
+ list_add(&inode->i_list, &inode_unused);
spin_unlock(&wb_inode_list_lock);
+ atomic_inc(&inodes_stat.nr_unused);
}
- atomic_inc(&inodes_stat.nr_unused);
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
@@ -1376,11 +1365,13 @@ static void generic_forget_inode(struct
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
__remove_inode_hash(inode);
+ }
+ if (!list_empty(&inode->i_list)) {
+ spin_lock(&wb_inode_list_lock);
+ list_del_init(&inode->i_list);
+ spin_unlock(&wb_inode_list_lock);
atomic_dec(&inodes_stat.nr_unused);
}
- spin_lock(&wb_inode_list_lock);
- list_del_init(&inode->i_list);
- spin_unlock(&wb_inode_list_lock);
list_del_init(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
@@ -1705,7 +1696,7 @@ void __init inode_init(void)

inode_hashtable =
alloc_large_system_hash("Inode-cache",
- sizeof(struct hlist_head),
+ sizeof(struct inode_hash_bucket),
ihash_entries,
14,
0,
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -2166,7 +2166,6 @@ extern int insert_inode_locked4(struct i
extern int insert_inode_locked(struct inode *);
extern void unlock_new_inode(struct inode *);

-extern void __iget(struct inode * inode);
extern void iget_failed(struct inode *);
extern void clear_inode(struct inode *);
extern void destroy_inode(struct inode *);
@@ -2384,6 +2383,12 @@ extern int generic_show_options(struct s
extern void save_mount_options(struct super_block *sb, char *options);
extern void replace_mount_options(struct super_block *sb, char *options);

+static inline void __iget(struct inode *inode)
+{
+ assert_spin_locked(&inode->i_lock);
+ inode->i_count++;
+}
+
static inline ino_t parent_ino(struct dentry *dentry)
{
ino_t res;
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -429,7 +429,7 @@ writeback_single_inode(struct inode *ino
/*
* The inode is clean, inuse
*/
- list_move(&inode->i_list, &inode_in_use);
+ list_del_init(&inode->i_list);
} else {
/*
* The inode is clean, unused
Index: linux-2.6/include/linux/writeback.h
===================================================================
--- linux-2.6.orig/include/linux/writeback.h
+++ linux-2.6/include/linux/writeback.h
@@ -11,7 +11,6 @@ struct backing_dev_info;

extern spinlock_t sb_inode_list_lock;
extern spinlock_t wb_inode_list_lock;
-extern struct list_head inode_in_use;
extern struct list_head inode_unused;

/*



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