To make in possible we need to know the exact frag queue
size for inet_frags->mem management and two callbacks:

 * to destoy the skb (optional, used in conntracks only)
 * to free the queue itself (mandatory, but later I plan to 
   move the allocation and the destruction of frag_queues 
   into the common place, so this callback will most likely
   be optional too).

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index e374412..2dd1cd4 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -33,16 +33,21 @@ struct inet_frags {
 	rwlock_t		lock;
 	u32			rnd;
 	int			nqueues;
+	int			qsize;
 	atomic_t		mem;
 	struct timer_list	secret_timer;
 	struct inet_frags_ctl	*ctl;
 
 	unsigned int		(*hashfn)(struct inet_frag_queue *);
+	void			(*destructor)(struct inet_frag_queue *);
+	void			(*skb_free)(struct sk_buff *);
 };
 
 void inet_frags_init(struct inet_frags *);
 void inet_frags_fini(struct inet_frags *);
 
 void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
+void inet_frag_destroy(struct inet_frag_queue *q,
+				struct inet_frags *f, int *work);
 
 #endif
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index ec10e05..15fb2c4 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -17,6 +17,8 @@
 #include <linux/timer.h>
 #include <linux/mm.h>
 #include <linux/random.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
 
 #include <net/inet_frag.h>
 
@@ -100,3 +102,41 @@ void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
 }
 
 EXPORT_SYMBOL(inet_frag_kill);
+
+static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb,
+						int *work)
+{
+	if (work)
+		*work -= skb->truesize;
+
+	atomic_sub(skb->truesize, &f->mem);
+	if (f->skb_free)
+		f->skb_free(skb);
+	kfree_skb(skb);
+}
+
+void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
+					int *work)
+{
+	struct sk_buff *fp;
+
+	BUG_TRAP(q->last_in & COMPLETE);
+	BUG_TRAP(del_timer(&q->timer) == 0);
+
+	/* Release all fragment data. */
+	fp = q->fragments;
+	while (fp) {
+		struct sk_buff *xp = fp->next;
+
+		frag_kfree_skb(f, fp, work);
+		fp = xp;
+	}
+
+	if (work)
+		*work -= f->qsize;
+	atomic_sub(f->qsize, &f->mem);
+
+	f->destructor(q);
+
+}
+EXPORT_SYMBOL(inet_frag_destroy);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 7aee137..a59ac39 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -129,11 +129,13 @@ static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work)
 	kfree_skb(skb);
 }
 
-static __inline__ void frag_free_queue(struct ipq *qp, int *work)
+static __inline__ void ip4_frag_free(struct inet_frag_queue *q)
 {
-	if (work)
-		*work -= sizeof(struct ipq);
-	atomic_sub(sizeof(struct ipq), &ip4_frags.mem);
+	struct ipq *qp;
+
+	qp = container_of(q, struct ipq, q);
+	if (qp->peer)
+		inet_putpeer(qp->peer);
 	kfree(qp);
 }
 
@@ -150,34 +152,10 @@ static __inline__ struct ipq *frag_alloc_queue(void)
 
 /* Destruction primitives. */
 
-/* Complete destruction of ipq. */
-static void ip_frag_destroy(struct ipq *qp, int *work)
-{
-	struct sk_buff *fp;
-
-	BUG_TRAP(qp->q.last_in&COMPLETE);
-	BUG_TRAP(del_timer(&qp->q.timer) == 0);
-
-	if (qp->peer)
-		inet_putpeer(qp->peer);
-
-	/* Release all fragment data. */
-	fp = qp->q.fragments;
-	while (fp) {
-		struct sk_buff *xp = fp->next;
-
-		frag_kfree_skb(fp, work);
-		fp = xp;
-	}
-
-	/* Finally, release the queue descriptor itself. */
-	frag_free_queue(qp, work);
-}
-
 static __inline__ void ipq_put(struct ipq *ipq, int *work)
 {
 	if (atomic_dec_and_test(&ipq->q.refcnt))
-		ip_frag_destroy(ipq, work);
+		inet_frag_destroy(&ipq->q, &ip4_frags, work);
 }
 
 /* Kill ipq entry. It is not destroyed immediately,
@@ -687,6 +665,9 @@ void __init ipfrag_init(void)
 {
 	ip4_frags.ctl = &ip4_frags_ctl;
 	ip4_frags.hashfn = ip4_hashfn;
+	ip4_frags.destructor = ip4_frag_free;
+	ip4_frags.skb_free = NULL;
+	ip4_frags.qsize = sizeof(struct ipq);
 	inet_frags_init(&ip4_frags);
 }
 
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index a3aef38..785f5cd 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -114,25 +114,25 @@ static unsigned int nf_hashfn(struct inet_frag_queue *q)
 	return ip6qhashfn(nq->id, &nq->saddr, &nq->daddr);
 }
 
+static void nf_skb_free(struct sk_buff *skb)
+{
+	if (NFCT_FRAG6_CB(skb)->orig)
+		kfree_skb(NFCT_FRAG6_CB(skb)->orig);
+}
+
 /* Memory Tracking Functions. */
 static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
 {
 	if (work)
 		*work -= skb->truesize;
 	atomic_sub(skb->truesize, &nf_frags.mem);
-	if (NFCT_FRAG6_CB(skb)->orig)
-		kfree_skb(NFCT_FRAG6_CB(skb)->orig);
-
+	nf_skb_free(skb);
 	kfree_skb(skb);
 }
 
-static inline void frag_free_queue(struct nf_ct_frag6_queue *fq,
-				   unsigned int *work)
+static void nf_frag_free(struct inet_frag_queue *q)
 {
-	if (work)
-		*work -= sizeof(struct nf_ct_frag6_queue);
-	atomic_sub(sizeof(struct nf_ct_frag6_queue), &nf_frags.mem);
-	kfree(fq);
+	kfree(container_of(q, struct nf_ct_frag6_queue, q));
 }
 
 static inline struct nf_ct_frag6_queue *frag_alloc_queue(void)
@@ -147,31 +147,10 @@ static inline struct nf_ct_frag6_queue *frag_alloc_queue(void)
 
 /* Destruction primitives. */
 
-/* Complete destruction of fq. */
-static void nf_ct_frag6_destroy(struct nf_ct_frag6_queue *fq,
-				unsigned int *work)
-{
-	struct sk_buff *fp;
-
-	BUG_TRAP(fq->q.last_in&COMPLETE);
-	BUG_TRAP(del_timer(&fq->q.timer) == 0);
-
-	/* Release all fragment data. */
-	fp = fq->q.fragments;
-	while (fp) {
-		struct sk_buff *xp = fp->next;
-
-		frag_kfree_skb(fp, work);
-		fp = xp;
-	}
-
-	frag_free_queue(fq, work);
-}
-
 static __inline__ void fq_put(struct nf_ct_frag6_queue *fq, unsigned int *work)
 {
 	if (atomic_dec_and_test(&fq->q.refcnt))
-		nf_ct_frag6_destroy(fq, work);
+		inet_frag_destroy(&fq->q, &nf_frags, work);
 }
 
 /* Kill fq entry. It is not destroyed immediately,
@@ -799,6 +778,9 @@ int nf_ct_frag6_init(void)
 {
 	nf_frags.ctl = &nf_frags_ctl;
 	nf_frags.hashfn = nf_hashfn;
+	nf_frags.destructor = nf_frag_free;
+	nf_frags.skb_free = nf_skb_free;
+	nf_frags.qsize = sizeof(struct nf_ct_frag6_queue);
 	inet_frags_init(&nf_frags);
 
 	return 0;
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 7a357fd..74b2113 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -148,12 +148,9 @@ static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 	kfree_skb(skb);
 }
 
-static inline void frag_free_queue(struct frag_queue *fq, int *work)
+static void ip6_frag_free(struct inet_frag_queue *fq)
 {
-	if (work)
-		*work -= sizeof(struct frag_queue);
-	atomic_sub(sizeof(struct frag_queue), &ip6_frags.mem);
-	kfree(fq);
+	kfree(container_of(fq, struct frag_queue, q));
 }
 
 static inline struct frag_queue *frag_alloc_queue(void)
@@ -168,30 +165,10 @@ static inline struct frag_queue *frag_alloc_queue(void)
 
 /* Destruction primitives. */
 
-/* Complete destruction of fq. */
-static void ip6_frag_destroy(struct frag_queue *fq, int *work)
-{
-	struct sk_buff *fp;
-
-	BUG_TRAP(fq->q.last_in&COMPLETE);
-	BUG_TRAP(del_timer(&fq->q.timer) == 0);
-
-	/* Release all fragment data. */
-	fp = fq->q.fragments;
-	while (fp) {
-		struct sk_buff *xp = fp->next;
-
-		frag_kfree_skb(fp, work);
-		fp = xp;
-	}
-
-	frag_free_queue(fq, work);
-}
-
 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 {
 	if (atomic_dec_and_test(&fq->q.refcnt))
-		ip6_frag_destroy(fq, work);
+		inet_frag_destroy(&fq->q, &ip6_frags, work);
 }
 
 /* Kill fq entry. It is not destroyed immediately,
@@ -721,5 +698,8 @@ void __init ipv6_frag_init(void)
 
 	ip6_frags.ctl = &ip6_frags_ctl;
 	ip6_frags.hashfn = ip6_hashfn;
+	ip6_frags.destructor = ip6_frag_free;
+	ip6_frags.skb_free = NULL;
+	ip6_frags.qsize = sizeof(struct frag_queue);
 	inet_frags_init(&ip6_frags);
 }
-- 
1.5.3.4