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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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