zero-copy.6

实现linux平台下零拷贝技术的软件包。

+	int			(* zc_alloc_data)(struct zc_buf *zb);
+	int			(* zc_commit_data)(struct zc_buf *zb);
+	wait_queue_head_t	zc_data_ready;
+	spinlock_t		zc_lock;
+	struct zc_page		*zc_pages;
+	unsigned int		zc_page_num, zc_page_index;
+	unsigned int		zc_users;
 };
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1663,7 +1663,7 @@ EXPORT_SYMBOL(read_cache_page);
  * caller's lru-buffering pagevec.  This function is specifically for
  * generic_file_write().
  */
-static inline struct page *
+struct page *
 __grab_cache_page(struct address_space *mapping, unsigned long index,
 			struct page **cached_page, struct pagevec *lru_pvec)
 {
@@ -1692,6 +1692,8 @@ repeat:
 	return page;
 }
 
+EXPORT_SYMBOL_GPL(__grab_cache_page);
+
 /*
  * The logic we want is
  *
diff --git a/net/core/Makefile b/net/core/Makefile
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -3,7 +3,7 @@
 #
 
 obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \
-	 gen_stats.o gen_estimator.o
+	 gen_stats.o gen_estimator.o zerocopy.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
diff --git a/net/core/datagram.c b/net/core/datagram.c
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -213,6 +213,10 @@ int skb_copy_datagram_iovec(const struct
 {
 	int i, err, fraglen, end = 0;
 	struct sk_buff *next = skb_shinfo(skb)->frag_list;
+
+	if (skb->zerocopy)
+		return 0;
+	
 next_skb:
 	fraglen = skb_headlen(skb);
 	i = -1;
@@ -364,6 +368,9 @@ int skb_copy_and_csum_datagram_iovec(con
 {
 	unsigned int csum;
 	int chunk = skb->len - hlen;
+	
+	if (skb->zerocopy)
+		return 0;
 
 	/* Skip filled elements.
 	 * Pretty silly, look at memcpy_toiovec, though 8)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -70,6 +70,7 @@
 
 static kmem_cache_t *skbuff_head_cache __read_mostly;
 static kmem_cache_t *skbuff_fclone_cache __read_mostly;
+static kmem_cache_t *skbuff_head_cache_zerocopy __read_mostly;
 
 /*
  *	Keep out-of-line to prevent kernel bloat.
@@ -182,6 +183,64 @@ nodata:
 	goto out;
 }
 
+int zc_alloc_data(struct zc_buf *zb);
+int zc_commit_data(struct zc_buf *zb);
+
+struct sk_buff *__alloc_skb_zerocopy(struct zc_buf *zb, gfp_t gfp_mask)
+{
+	struct sk_buff *skb = NULL;
+	void *data;
+	int err;
+	unsigned int size = SKB_DATA_ALIGN(zb->header_size);
+
+	if (size > ZEROCOPY_HEADER_CACHE_SIZE)
+		goto out;
+	
+	zb->status = -1;
+
+	skb = kmem_cache_alloc(skbuff_head_cache, gfp_mask & ~__GFP_DMA);
+	if (!skb)
+		goto out;
+	
+	data = kmem_cache_alloc(skbuff_head_cache_zerocopy, gfp_mask & ~__GFP_DMA);
+	if (!data)
+		goto err_out_free_skb;
+
+	memset(skb, 0, offsetof(struct sk_buff, truesize));
+	skb->truesize = size + sizeof(struct sk_buff);
+	atomic_set(&skb->users, 1);
+	skb->head = data;
+	skb->data = data;
+	skb->tail = data;
+	skb->end  = data + size;
+	
+	atomic_set(&(skb_shinfo(skb)->dataref), 1);
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb_shinfo(skb)->tso_size = 0;
+	skb_shinfo(skb)->tso_segs = 0;
+	skb_shinfo(skb)->frag_list = NULL;
+
+	skb->zerocopy = 1;
+	/* It could be zerocopied too, but let's use it as is for now. --zbr 2005_10_27 */
+	memcpy(skb->data, zb->header, zb->header_size);
+	skb_put(skb, zb->header_size);
+
+	zb->skb = skb;
+
+	err = zc_alloc_data(zb);
+	if (err)
+		goto err_out_free_skb_data;
+	
+out:
+	return skb;
+err_out_free_skb_data:
+	kmem_cache_free(skbuff_head_cache_zerocopy, data);
+err_out_free_skb:
+	kmem_cache_free(skbuff_head_cache, skb);
+	skb = NULL;
+	goto out;
+}
+
 /**
  *	alloc_skb_from_cache	-	allocate a network buffer
  *	@cp: kmem_cache from which to allocate the data area
@@ -284,7 +343,10 @@ void kfree_skbmem(struct sk_buff *skb)
 	struct sk_buff *other;
 	atomic_t *fclone_ref;
 
-	skb_release_data(skb);
+	if (skb->zerocopy)
+		kmem_cache_free(skbuff_head_cache_zerocopy, skb->head);
+	else
+		skb_release_data(skb);
 	switch (skb->fclone) {
 	case SKB_FCLONE_UNAVAILABLE:
 		kmem_cache_free(skbuff_head_cache, skb);
@@ -1706,6 +1768,14 @@ void __init skb_init(void)
 						NULL, NULL);
 	if (!skbuff_fclone_cache)
 		panic("cannot create skbuff cache");
+	
+	skbuff_head_cache_zerocopy = kmem_cache_create("skbuff_head_cache_zerocopy",
+					      ZEROCOPY_HEADER_CACHE_SIZE + sizeof(struct skb_shared_info),
+					      0,
+					      SLAB_HWCACHE_ALIGN,
+					      NULL, NULL);
+	if (!skbuff_head_cache_zerocopy)
+		panic("cannot create zerocopy skbuff cache");
 }
 
 EXPORT_SYMBOL(___pskb_trim);
@@ -1739,3 +1809,4 @@ EXPORT_SYMBOL(skb_prepare_seq_read);
 EXPORT_SYMBOL(skb_seq_read);
 EXPORT_SYMBOL(skb_abort_seq_read);
 EXPORT_SYMBOL(skb_find_text);
+EXPORT_SYMBOL(__alloc_skb_zerocopy);
diff --git a/net/core/sock.c b/net/core/sock.c
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -704,6 +704,18 @@ void sk_free(struct sock *sk)
 	module_put(owner);
 }
 
+static void zc_sk_init(struct sock *sk)
+{
+	spin_lock_init(&sk->zc_lock);
+	init_waitqueue_head(&sk->zc_data_ready);
+	sk->zc_pages		= NULL;
+	sk->zc_page_num		= 0;
+	sk->zc_page_index	= 0;
+	sk->zc_alloc_data	= NULL;
+	sk->zc_commit_data	= NULL;
+}
+
+
 struct sock *sk_clone(const struct sock *sk, const gfp_t priority)
 {
 	struct sock *newsk = sk_alloc(sk->sk_family, priority, sk->sk_prot, 0);
@@ -737,6 +749,8 @@ struct sock *sk_clone(const struct sock 
 		sock_reset_flag(newsk, SOCK_DONE);
 		skb_queue_head_init(&newsk->sk_error_queue);
 
+		zc_sk_init(newsk);
+
 		filter = newsk->sk_filter;
 		if (filter != NULL)
 			sk_filter_charge(newsk, filter);
@@ -1320,6 +1334,8 @@ void sock_init_data(struct socket *sock,
 	sk->sk_stamp.tv_usec    = -1L;
 
 	atomic_set(&sk->sk_refcnt, 1);
+
+	zc_sk_init(sk);
 }
 
 void fastcall lock_sock(struct sock *sk)
diff --git a/net/core/zerocopy.c b/net/core/zerocopy.c
new file mode 100644
--- /dev/null
+++ b/net/core/zerocopy.c
@@ -0,0 +1,165 @@
+/*
+ * 	zerocopy.c
+ * 
+ * 2005 Copyright (c) Evgeniy Polyakov <[e-mail]>
+ * All rights reserved.
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+
+#include <net/inet_hashtables.h>
+
+static int tcp_sendfile_alloc_data(struct zc_buf *zb);
+static int tcp_sendfile_commit_data(struct zc_buf *zb);
+
+static struct zc_handler zc_tcp_sendfile_handler = {
+	.alloc_data		= &tcp_sendfile_alloc_data,
+	.commit_data		= &tcp_sendfile_commit_data,
+};
+
+static DEFINE_SPINLOCK(zc_lock);
+static LIST_HEAD(zc_list);
+
+int zc_alloc_data(struct zc_buf *zb)
+{
+	struct zc_handler *zh;
+	int err = -ENODEV;
+
+	if (unlikely(zb->size > PAGE_SIZE))
+		return err;
+	
+	rcu_read_lock();
+	list_for_each_entry_rcu(zh, &zc_list, zc_entry) {
+		err = zh->alloc_data(zb);
+		if (!err) {
+			zb->zh = zh;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return err;
+}
+
+int zc_commit_data(struct zc_buf *zb)
+{
+	int err = -EINVAL;
+	
+	if (zb->zh)
+		err = zb->zh->commit_data(zb);
+	
+	return err;
+}
+
+int zc_add_handler(struct zc_handler *h)
+{
+	if (!h->alloc_data || !h->commit_data)
+		return -EINVAL;
+
+	spin_lock(&zc_lock);
+	list_add_rcu(&h->zc_entry, &zc_list);
+	spin_unlock(&zc_lock);
+
+	return 0;
+}
+
+void zc_del_handler(struct zc_handler *h)
+{
+	spin_lock(&zc_lock);
+	list_del_rcu(&h->zc_entry);
+	spin_unlock(&zc_lock);
+
+	synchronize_rcu();
+}
+
+extern struct inet_hashinfo __cacheline_aligned tcp_hashinfo;
+
+static int tcp_sendfile_alloc_data(struct zc_buf *zb)
+{
+	struct ethhdr *eth;
+	struct iphdr *iph;
+	struct tcphdr *tcph;
+	struct sock *sk;
+	int dif, err = -EINVAL;
+	u32 saddr, daddr;
+	u16 sport, dport;
+	
+	if (zb->header_size < sizeof(struct ethhdr) + sizeof(struct iphdr) + sizeof(struct tcphdr))
+		goto err_out_exit;
+
+	eth = zb->header;
+
+	if (eth->h_proto != htons(ETH_P_IP))
+		goto err_out_exit;
+	
+	iph = (struct iphdr *)(eth + 1);
+
+	if (iph->protocol != IPPROTO_TCP)
+		goto err_out_exit;
+	
+	tcph = (struct tcphdr *)(iph + 1);
+
+	dif = 0;
+	
+	saddr = iph->saddr;
+	sport = tcph->source;
+	daddr = iph->daddr;
+	dport = tcph->dest;
+	
+	/*
+	 * I suspect it is not enough to disable BHs,
+	 * since it can be [and is] called from hard IRQ context.
+	 * Must do something with bound devices.
+	 */
+	sk = inet_lookup(&tcp_hashinfo, saddr, sport, daddr, dport, dif);
+
+	if (sk && sk->zc_alloc_data) {
+		zb->priv = sk;
+		err = sk->zc_alloc_data(zb);
+		zb->status = (err)?1:0;
+	}
+#if 0
+	printk("%s: sk=%p, %u.%u.%u.%u:%u -> %u.%u.%u.%u:%u, data=%p, status=%d, err=%d.\n", 
+			__func__, sk, 
+			NIPQUAD(saddr), ntohs(sport),
+			NIPQUAD(daddr), ntohs(dport),
+			zb->skb->data, zb->status, err);
+#endif	
+err_out_exit:
+	return err;
+}
+
+static int tcp_sendfile_commit_data(struct zc_buf *zb)
+{
+	struct sock *sk = zb->priv;
+	int err;
+
+	err = sk->zc_commit_data(zb);
+	
+	printk("%s: commiting data, sk=%p, size=%4u, err=%d.\n", __func__, sk, zb->size, err);
+
+	return err;
+}
+
+int __init zc_add_tcp(void)
+{
+	return zc_add_handler(&zc_tcp_sendfile_handler);
+}
+
+late_initcall(zc_add_tcp);
diff --git a/net/socket.c b/net/socket.c
--- a/net/socket.c
+++ b/net/socket.c
@@ -44,6 +44,7 @@
  *		Tigran Aivazian	:	sys_send(args) calls sys_sendto(args, NULL, 0)
  *		Tigran Aivazian	:	Made listen(2) backlog sanity checks 
  *					protocol-independent
+ *		Evgeniy Polyakov:	Added sock_sendfile().
  *
  *
  *		This program is free software; you can redistribute it and/or
@@ -84,6 +85,10 @@
 #include <linux/compat.h>
 #include <linux/kmod.h>
 #include <linux/audit.h>
+#include <linux/pagevec.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
 
 #ifdef CONFIG_NET_RADIO
 #include <linux/wireless.h>		/* Note : will define WIRELESS_EXT */
@@ -116,6 +121,7 @@ static ssize_t sock_writev(struct file *
 			  unsigned long count, loff_t *ppos);
 static ssize_t sock_sendpage(struct file *file, struct page *page,
 			     int offset, size_t size, loff_t *ppos, int more);