[AF_PACKET]: Convert PACKET_MMAP over to vm_insert_page().

So we can properly use __GFP_COMP and avoid the use of
PG_reserved pages.

With extremely helpful review from Hugh Dickins.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -1587,23 +1587,47 @@ static inline struct page *pg_vec_endpage(char *one_pg_vec, unsigned int order)
 	return virt_to_page(one_pg_vec + (PAGE_SIZE << order) - 1);
 }
 
-static void free_pg_vec(char **pg_vec, unsigned order, unsigned len)
+static void free_pg_vec(char **pg_vec, unsigned int order, unsigned int len)
 {
 	int i;
 
-	for (i=0; i<len; i++) {
-		if (pg_vec[i]) {
-			struct page *page, *pend;
-
-			pend = pg_vec_endpage(pg_vec[i], order);
-			for (page = virt_to_page(pg_vec[i]); page <= pend; page++)
-				ClearPageReserved(page);
-			free_pages((unsigned long)pg_vec[i], order);
-		}
+	for (i = 0; i < len; i++) {
+		if (likely(pg_vec[i]))
+			free_pages((unsigned long) pg_vec[i], order);
 	}
 	kfree(pg_vec);
 }
 
+static inline char *alloc_one_pg_vec_page(unsigned long order)
+{
+	return (char *) __get_free_pages(GFP_KERNEL | __GFP_COMP | __GFP_ZERO,
+					 order);
+}
+
+static char **alloc_pg_vec(struct tpacket_req *req, int order)
+{
+	unsigned int block_nr = req->tp_block_nr;
+	char **pg_vec;
+	int i;
+
+	pg_vec = kzalloc(block_nr * sizeof(char *), GFP_KERNEL);
+	if (unlikely(!pg_vec))
+		goto out;
+
+	for (i = 0; i < block_nr; i++) {
+		pg_vec[i] = alloc_one_pg_vec_page(order);
+		if (unlikely(!pg_vec[i]))
+			goto out_free_pgvec;
+	}
+
+out:
+	return pg_vec;
+
+out_free_pgvec:
+	free_pg_vec(pg_vec, order, block_nr);
+	pg_vec = NULL;
+	goto out;
+}
 
 static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing)
 {
@@ -1617,64 +1641,46 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
 
 		/* Sanity tests and some calculations */
 
-		if (po->pg_vec)
+		if (unlikely(po->pg_vec))
 			return -EBUSY;
 
-		if ((int)req->tp_block_size <= 0)
+		if (unlikely((int)req->tp_block_size <= 0))
 			return -EINVAL;
-		if (req->tp_block_size&(PAGE_SIZE-1))
+		if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
 			return -EINVAL;
-		if (req->tp_frame_size < TPACKET_HDRLEN)
+		if (unlikely(req->tp_frame_size < TPACKET_HDRLEN))
 			return -EINVAL;
-		if (req->tp_frame_size&(TPACKET_ALIGNMENT-1))
+		if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1)))
 			return -EINVAL;
 
 		po->frames_per_block = req->tp_block_size/req->tp_frame_size;
-		if (po->frames_per_block <= 0)
+		if (unlikely(po->frames_per_block <= 0))
 			return -EINVAL;
-		if (po->frames_per_block*req->tp_block_nr != req->tp_frame_nr)
+		if (unlikely((po->frames_per_block * req->tp_block_nr) !=
+			     req->tp_frame_nr))
 			return -EINVAL;
-		/* OK! */
-
-		/* Allocate page vector */
-		while ((PAGE_SIZE<<order) < req->tp_block_size)
-			order++;
 
 		err = -ENOMEM;
-
-		pg_vec = kmalloc(req->tp_block_nr*sizeof(char *), GFP_KERNEL);
-		if (pg_vec == NULL)
+		order = get_order(req->tp_block_size);
+		pg_vec = alloc_pg_vec(req, order);
+		if (unlikely(!pg_vec))
 			goto out;
-		memset(pg_vec, 0, req->tp_block_nr*sizeof(char **));
-
-		for (i=0; i<req->tp_block_nr; i++) {
-			struct page *page, *pend;
-			pg_vec[i] = (char *)__get_free_pages(GFP_KERNEL, order);
-			if (!pg_vec[i])
-				goto out_free_pgvec;
-
-			pend = pg_vec_endpage(pg_vec[i], order);
-			for (page = virt_to_page(pg_vec[i]); page <= pend; page++)
-				SetPageReserved(page);
-		}
-		/* Page vector is allocated */
 
 		l = 0;
-		for (i=0; i<req->tp_block_nr; i++) {
+		for (i = 0; i < req->tp_block_nr; i++) {
 			char *ptr = pg_vec[i];
 			struct tpacket_hdr *header;
 			int k;
 
-			for (k=0; k<po->frames_per_block; k++) {
-				
-				header = (struct tpacket_hdr*)ptr;
+			for (k = 0; k < po->frames_per_block; k++) {
+				header = (struct tpacket_hdr *) ptr;
 				header->tp_status = TP_STATUS_KERNEL;
 				ptr += req->tp_frame_size;
 			}
 		}
 		/* Done */
 	} else {
-		if (req->tp_frame_nr)
+		if (unlikely(req->tp_frame_nr))
 			return -EINVAL;
 	}
 
@@ -1701,7 +1707,7 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
 
 		spin_lock_bh(&sk->sk_receive_queue.lock);
 		pg_vec = XC(po->pg_vec, pg_vec);
-		po->frame_max = req->tp_frame_nr-1;
+		po->frame_max = (req->tp_frame_nr - 1);
 		po->head = 0;
 		po->frame_size = req->tp_frame_size;
 		spin_unlock_bh(&sk->sk_receive_queue.lock);
@@ -1728,7 +1734,6 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
 
 	release_sock(sk);
 
-out_free_pgvec:
 	if (pg_vec)
 		free_pg_vec(pg_vec, order, req->tp_block_nr);
 out:
@@ -1755,17 +1760,19 @@ static int packet_mmap(struct file *file, struct socket *sock, struct vm_area_st
 	if (size != po->pg_vec_len*po->pg_vec_pages*PAGE_SIZE)
 		goto out;
 
-	atomic_inc(&po->mapped);
 	start = vma->vm_start;
-	err = -EAGAIN;
-	for (i=0; i<po->pg_vec_len; i++) {
-		if (remap_pfn_range(vma, start,
-				     __pa(po->pg_vec[i]) >> PAGE_SHIFT,
-				     po->pg_vec_pages*PAGE_SIZE,
-				     vma->vm_page_prot))
-			goto out;
-		start += po->pg_vec_pages*PAGE_SIZE;
+	for (i = 0; i < po->pg_vec_len; i++) {
+		struct page *page = virt_to_page(po->pg_vec[i]);
+		int pg_num;
+
+		for (pg_num = 0; pg_num < po->pg_vec_pages; pg_num++, page++) {
+			err = vm_insert_page(vma, start, page);
+			if (unlikely(err))
+				goto out;
+			start += PAGE_SIZE;
+		}
 	}
+	atomic_inc(&po->mapped);
 	vma->vm_ops = &packet_mmap_ops;
 	err = 0;