[BLK] back: Allocate pages for foreign mappings individually rather

than in one large contiguous region.
Signed-off-by: Keir Fraser <keir@xensource.com>

3 files changed, 44 insertions, 39 deletions

diff --git a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
index a6a8396c05..ad39655661 100644
--- a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
+++ b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
@@ -606,6 +606,17 @@ void balloon_dealloc_empty_page_range(
 	schedule_work(&balloon_worker);
 }
 
+struct page *balloon_alloc_empty_page(void)
+{
+	return balloon_alloc_empty_page_range(1);
+}
+
+void balloon_free_empty_page(
+	struct page *page)
+{
+	balloon_dealloc_empty_page_range(page, 1);
+}
+
 void balloon_release_driver_page(struct page *page)
 {
 	unsigned long flags;
@@ -621,6 +632,8 @@ void balloon_release_driver_page(struct page *page)
 EXPORT_SYMBOL_GPL(balloon_update_driver_allowance);
 EXPORT_SYMBOL_GPL(balloon_alloc_empty_page_range);
 EXPORT_SYMBOL_GPL(balloon_dealloc_empty_page_range);
+EXPORT_SYMBOL_GPL(balloon_alloc_empty_page);
+EXPORT_SYMBOL_GPL(balloon_free_empty_page);
 EXPORT_SYMBOL_GPL(balloon_release_driver_page);
 
 MODULE_LICENSE("Dual BSD/GPL");
diff --git a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
index 416f7bc18c..5d5856d8f9 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
@@ -56,8 +56,6 @@ static int blkif_reqs = 64;
 module_param_named(reqs, blkif_reqs, int, 0);
 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate");
 
-static int mmap_pages;
-
 /* Run-time switchable: /sys/module/blkback/parameters/ */
 static unsigned int log_stats = 0;
 static unsigned int debug_lvl = 0;
@@ -87,8 +85,7 @@ static DECLARE_WAIT_QUEUE_HEAD(pending_free_wq);
 
 #define BLKBACK_INVALID_HANDLE (~0)
 
-static unsigned long mmap_vstart;
-static unsigned long *pending_vaddrs;
+static struct page **pending_pages;
 static grant_handle_t *pending_grant_handles;
 
 static inline int vaddr_pagenr(pending_req_t *req, int seg)
@@ -98,7 +95,8 @@ static inline int vaddr_pagenr(pending_req_t *req, int seg)
 
 static inline unsigned long vaddr(pending_req_t *req, int seg)
 {
-	return pending_vaddrs[vaddr_pagenr(req, seg)];
+	unsigned long pfn = page_to_pfn(pending_pages[vaddr_pagenr(req, seg)]);
+	return (unsigned long)pfn_to_kaddr(pfn);
 }
 
 #define pending_handle(_req, _seg) \
@@ -506,52 +504,50 @@ static void make_response(blkif_t *blkif, unsigned long id,
 
 static int __init blkif_init(void)
 {
-	struct page *page;
-	int i;
+	int i, mmap_pages;
 
 	if (!is_running_on_xen())
 		return -ENODEV;
 
-	mmap_pages            = blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
-
-	page = balloon_alloc_empty_page_range(mmap_pages);
-	if (page == NULL)
-		return -ENOMEM;
-	mmap_vstart = (unsigned long)pfn_to_kaddr(page_to_pfn(page));
+	mmap_pages = blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
 
 	pending_reqs          = kmalloc(sizeof(pending_reqs[0]) *
 					blkif_reqs, GFP_KERNEL);
 	pending_grant_handles = kmalloc(sizeof(pending_grant_handles[0]) *
 					mmap_pages, GFP_KERNEL);
-	pending_vaddrs        = kmalloc(sizeof(pending_vaddrs[0]) *
+	pending_pages         = kmalloc(sizeof(pending_pages[0]) *
 					mmap_pages, GFP_KERNEL);
-	if (!pending_reqs || !pending_grant_handles || !pending_vaddrs) {
-		kfree(pending_reqs);
-		kfree(pending_grant_handles);
-		kfree(pending_vaddrs);
-		printk("%s: out of memory\n", __FUNCTION__);
-		return -ENOMEM;
-	}
+	if (!pending_reqs || !pending_grant_handles || !pending_pages)
+		goto out_of_memory;
 
-	blkif_interface_init();
-	
-	printk("%s: reqs=%d, pages=%d, mmap_vstart=0x%lx\n",
-	       __FUNCTION__, blkif_reqs, mmap_pages, mmap_vstart);
-	BUG_ON(mmap_vstart == 0);
 	for (i = 0; i < mmap_pages; i++) {
-		pending_vaddrs[i] = mmap_vstart + (i << PAGE_SHIFT);
+		pending_pages[i] = balloon_alloc_empty_page();
+		if (pending_pages[i] == NULL) {
+			while (--i >= 0)
+				balloon_free_empty_page(pending_pages[i]);
+			goto out_of_memory;
+		}
 		pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
 	}
 
+	blkif_interface_init();
+
 	memset(pending_reqs, 0, sizeof(pending_reqs));
 	INIT_LIST_HEAD(&pending_free);
 
 	for (i = 0; i < blkif_reqs; i++)
 		list_add_tail(&pending_reqs[i].free_list, &pending_free);
-    
+
 	blkif_xenbus_init();
 
 	return 0;
+
+ out_of_memory:
+	kfree(pending_reqs);
+	kfree(pending_grant_handles);
+	kfree(pending_pages);
+	printk("%s: out of memory\n", __FUNCTION__);
+	return -ENOMEM;
 }
 
 module_init(blkif_init);
diff --git a/linux-2.6-xen-sparse/include/xen/balloon.h b/linux-2.6-xen-sparse/include/xen/balloon.h
index 60d7099aa1..4e27a2e39a 100644
--- a/linux-2.6-xen-sparse/include/xen/balloon.h
+++ b/linux-2.6-xen-sparse/include/xen/balloon.h
@@ -38,23 +38,19 @@
  * Inform the balloon driver that it should allow some slop for device-driver
  * memory activities.
  */
-void
-balloon_update_driver_allowance(
-	long delta);
+void balloon_update_driver_allowance(long delta);
 
 /* Allocate an empty low-memory page range. */
-struct page *
-balloon_alloc_empty_page_range(
-	unsigned long nr_pages);
+struct page *balloon_alloc_empty_page_range(unsigned long nr_pages);
 
 /* Deallocate an empty page range, adding to the balloon. */
-void
-balloon_dealloc_empty_page_range(
+void balloon_dealloc_empty_page_range(
 	struct page *page, unsigned long nr_pages);
 
-void
-balloon_release_driver_page(
-	struct page *page);
+struct page *balloon_alloc_empty_page(void);
+void balloon_free_empty_page(struct page *page);
+
+void balloon_release_driver_page(struct page *page);
 
 /*
  * Prevent the balloon driver from changing the memory reservation during