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    Subject[patch 1/3] dentries: Always use list_del_init() when removing a dentry from the lru
    The patch restores what commit 4a0962abd187df29b7d1378b2f372a55667d54c0
    already implemented. The feature was subsequently clobbered by
    commit da3bbdd4632c0171406b2677e31494afa5bde2f8

    Before this patch some execution path use list_del() instead of
    list_del_init() which results in inconsitencies in the state of d_lru
    when the object is freed.

    The performance of list_del_init() and list_del() is the same.
    So lets just have one dentry removal function named dentry_lru_del() that always
    does a list_del_init().

    The result of this patch is that dentry->d_lru is now always empty when a
    dentry is freed. The dentry defragmentation patch depends on a defined state
    of a dentry on free.

    Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

    Index: linux-next/fs/dcache.c
    ===================================================================
    --- linux-next.orig/fs/dcache.c 2008-08-25 15:44:58.000000000 -0500
    +++ linux-next/fs/dcache.c 2008-08-25 15:45:59.000000000 -0500
    @@ -141,15 +141,6 @@
    static void dentry_lru_del(struct dentry *dentry)
    {
    if (!list_empty(&dentry->d_lru)) {
    - list_del(&dentry->d_lru);
    - dentry->d_sb->s_nr_dentry_unused--;
    - dentry_stat.nr_unused--;
    - }
    -}
    -
    -static void dentry_lru_del_init(struct dentry *dentry)
    -{
    - if (likely(!list_empty(&dentry->d_lru))) {
    list_del_init(&dentry->d_lru);
    dentry->d_sb->s_nr_dentry_unused--;
    dentry_stat.nr_unused--;
    @@ -316,7 +307,7 @@
    static inline struct dentry * __dget_locked(struct dentry *dentry)
    {
    atomic_inc(&dentry->d_count);
    - dentry_lru_del_init(dentry);
    + dentry_lru_del(dentry);
    return dentry;
    }

    @@ -432,7 +423,7 @@

    if (dentry->d_op && dentry->d_op->d_delete)
    dentry->d_op->d_delete(dentry);
    - dentry_lru_del_init(dentry);
    + dentry_lru_del(dentry);
    __d_drop(dentry);
    dentry = d_kill(dentry);
    spin_lock(&dcache_lock);
    @@ -492,7 +483,7 @@
    }
    while (!list_empty(&tmp)) {
    dentry = list_entry(tmp.prev, struct dentry, d_lru);
    - dentry_lru_del_init(dentry);
    + dentry_lru_del(dentry);
    spin_lock(&dentry->d_lock);
    /*
    * We found an inuse dentry which was not removed from
    @@ -621,7 +612,7 @@

    /* detach this root from the system */
    spin_lock(&dcache_lock);
    - dentry_lru_del_init(dentry);
    + dentry_lru_del(dentry);
    __d_drop(dentry);
    spin_unlock(&dcache_lock);

    @@ -635,7 +626,7 @@
    spin_lock(&dcache_lock);
    list_for_each_entry(loop, &dentry->d_subdirs,
    d_u.d_child) {
    - dentry_lru_del_init(loop);
    + dentry_lru_del(loop);
    __d_drop(loop);
    cond_resched_lock(&dcache_lock);
    }
    @@ -817,7 +808,7 @@
    struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
    next = tmp->next;

    - dentry_lru_del_init(dentry);
    + dentry_lru_del(dentry);
    /*
    * move only zero ref count dentries to the end
    * of the unused list for prune_dcache
    --


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