In order to support defragmentation on the dentry cache we need to have
a determined object state at all times. Without a constructor the object
would have a random state after allocation.

Reviewed-by: Rik van Riel <[EMAIL PROTECTED]>
So provide a constructor.

Signed-off-by: Christoph Lameter <[EMAIL PROTECTED]>
---
 fs/dcache.c |   26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c  2007-11-06 12:56:56.000000000 -0800
+++ linux-2.6/fs/dcache.c       2007-11-06 12:57:01.000000000 -0800
@@ -870,6 +870,16 @@ static struct shrinker dcache_shrinker =
        .seeks = DEFAULT_SEEKS,
 };
 
+void dcache_ctor(struct kmem_cache *s, void *p)
+{
+       struct dentry *dentry = p;
+
+       spin_lock_init(&dentry->d_lock);
+       dentry->d_inode = NULL;
+       INIT_LIST_HEAD(&dentry->d_lru);
+       INIT_LIST_HEAD(&dentry->d_alias);
+}
+
 /**
  * d_alloc     -       allocate a dcache entry
  * @parent: parent of entry to allocate
@@ -907,8 +917,6 @@ struct dentry *d_alloc(struct dentry * p
 
        atomic_set(&dentry->d_count, 1);
        dentry->d_flags = DCACHE_UNHASHED;
-       spin_lock_init(&dentry->d_lock);
-       dentry->d_inode = NULL;
        dentry->d_parent = NULL;
        dentry->d_sb = NULL;
        dentry->d_op = NULL;
@@ -918,9 +926,7 @@ struct dentry *d_alloc(struct dentry * p
        dentry->d_cookie = NULL;
 #endif
        INIT_HLIST_NODE(&dentry->d_hash);
-       INIT_LIST_HEAD(&dentry->d_lru);
        INIT_LIST_HEAD(&dentry->d_subdirs);
-       INIT_LIST_HEAD(&dentry->d_alias);
 
        if (parent) {
                dentry->d_parent = dget(parent);
@@ -2096,14 +2102,10 @@ static void __init dcache_init(void)
 {
        int loop;
 
-       /* 
-        * A constructor could be added for stable state like the lists,
-        * but it is probably not worth it because of the cache nature
-        * of the dcache. 
-        */
-       dentry_cache = KMEM_CACHE(dentry,
-               SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
-       
+       dentry_cache = kmem_cache_create("dentry_cache", sizeof(struct dentry),
+               0, SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD,
+               dcache_ctor);
+
        register_shrinker(&dcache_shrinker);
 
        /* Hash may have been set up in dcache_init_early */

-- 
-
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