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Subject[patch 18/19] dentries: Add constructor
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.

So provide a constructor.

Cc: Alexander Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
fs/dcache.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
Index: linux-next/fs/dcache.c
===================================================================
--- linux-next.orig/fs/dcache.c 2008-08-11 07:42:10.072351650 -0700
+++ linux-next/fs/dcache.c 2008-08-11 07:50:02.361383352 -0700
@@ -899,6 +899,16 @@ static struct shrinker dcache_shrinker =
.seeks = DEFAULT_SEEKS,
};

+static void dcache_ctor(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
@@ -936,8 +946,6 @@ 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;
@@ -947,9 +955,7 @@ 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);
@@ -2275,14 +2281,10 @@ 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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