[RFC PATCH v6 5/7] bcache: bch_nvm_free_pages() of the buddy

[Qiaowei Ren <qiaowei.ren@intel.com>]

This patch implements the bch_nvm_free_pages() of the buddy.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
---
 drivers/md/bcache/nvm-pages.c | 143 ++++++++++++++++++++++++++++++++--
 drivers/md/bcache/nvm-pages.h |   3 +
 2 files changed, 138 insertions(+), 8 deletions(-)

diff --git a/drivers/md/bcache/nvm-pages.c b/drivers/md/bcache/nvm-pages.c
index 0b992c17ce47..b40bdbac873f 100644
--- a/drivers/md/bcache/nvm-pages.c
+++ b/drivers/md/bcache/nvm-pages.c
@@ -168,8 +168,7 @@ static inline void *extent_end_addr(struct bch_extent *extent)
 static void add_extent(struct bch_nvm_alloced_recs *alloced_recs, void *addr, int order)
 {
 	struct list_head *list = alloced_recs->extent_head.next;
-	struct bch_extent *extent, *tmp;
-	void *end_addr = addr + (((u64)1 << order) << PAGE_SHIFT);
+	struct bch_extent *extent;
 
 	while (list != &alloced_recs->extent_head) {
 		extent = container_of(list, struct bch_extent, list);
@@ -187,6 +186,136 @@ static void add_extent(struct bch_nvm_alloced_recs *alloced_recs, void *addr, in
 	alloced_recs->nr++;
 }
 
+static inline void *nvm_end_addr(struct bch_nvm_namespace *ns)
+{
+	return ns->kaddr + (ns->pages_total << PAGE_SHIFT);
+}
+
+static inline bool in_nvm_range(struct bch_nvm_namespace *ns,
+		void *start_addr, void *end_addr)
+{
+	return (start_addr >= ns->kaddr) && (end_addr <= nvm_end_addr(ns));
+}
+
+static struct bch_nvm_namespace *find_nvm_by_addr(void *addr, int order)
+{
+	int i;
+	struct bch_nvm_namespace *ns;
+
+	for (i = 0; i < only_set->total_namespaces_nr; i++) {
+		ns = only_set->nss[i];
+		if (ns && in_nvm_range(ns, addr, addr + (1 << order)))
+			return ns;
+	}
+	return NULL;
+}
+
+static int remove_extent(struct bch_nvm_alloced_recs *alloced_recs, void *addr, int order)
+{
+	struct list_head *list = alloced_recs->extent_head.next;
+	struct bch_extent *extent;
+
+	while (list != &alloced_recs->extent_head) {
+		extent = container_of(list, struct bch_extent, list);
+
+		if (addr < extent->kaddr)
+			return -ENOENT;
+		if (addr > extent->kaddr) {
+			list = list->next;
+			continue;
+		}
+
+		WARN_ON(extent->nr != (1 << order));
+		list_del(list);
+		kfree(extent);
+		alloced_recs->nr--;
+		break;
+	}
+	return (list == &alloced_recs->extent_head) ? -ENOENT : 0;
+}
+
+static void __free_space(struct bch_nvm_namespace *ns, void *addr, int order)
+{
+	unsigned int add_pages = (1 << order);
+	pgoff_t pgoff;
+	struct page *page;
+
+	page = nvm_vaddr_to_page(ns, addr);
+	WARN_ON((!page) || (page->private != order));
+	pgoff = page->index;
+
+	while (order < BCH_MAX_ORDER - 1) {
+		struct page *buddy_page;
+
+		pgoff_t buddy_pgoff = pgoff ^ (1 << order);
+		pgoff_t parent_pgoff = pgoff & ~(1 << order);
+
+		if ((parent_pgoff + (1 << (order + 1)) > ns->pages_total))
+			break;
+
+		buddy_page = nvm_vaddr_to_page(ns, nvm_pgoff_to_vaddr(ns, buddy_pgoff));
+		WARN_ON(!buddy_page);
+
+		if (PageBuddy(buddy_page) && (buddy_page->private == order)) {
+			list_del((struct list_head *)&buddy_page->zone_device_data);
+			__ClearPageBuddy(buddy_page);
+			pgoff = parent_pgoff;
+			order++;
+			continue;
+		}
+		break;
+	}
+
+	page = nvm_vaddr_to_page(ns, nvm_pgoff_to_vaddr(ns, pgoff));
+	WARN_ON(!page);
+	list_add((struct list_head *)&page->zone_device_data, &ns->free_area[order]);
+	page->index = pgoff;
+	set_page_private(page, order);
+	__SetPageBuddy(page);
+	ns->free += add_pages;
+}
+
+void bch_nvm_free_pages(void *addr, int order, const char *owner_uuid)
+{
+	struct bch_nvm_namespace *ns;
+	struct bch_owner_list *owner_list;
+	struct bch_nvm_alloced_recs *alloced_recs;
+	int r;
+
+	mutex_lock(&only_set->lock);
+
+	ns = find_nvm_by_addr(addr, order);
+	if (!ns) {
+		pr_info("can't find nvm_dev by kaddr %p\n", addr);
+		goto unlock;
+	}
+
+	owner_list = find_owner_list(owner_uuid, false);
+	if (!owner_list) {
+		pr_info("can't found owner(uuid=%s)\n", owner_uuid);
+		goto unlock;
+	}
+
+	alloced_recs = find_nvm_alloced_recs(owner_list, ns, false);
+	if (!alloced_recs) {
+		pr_info("can't find alloced_recs(uuid=%s)\n", ns->uuid);
+		goto unlock;
+	}
+
+	r = remove_extent(alloced_recs, addr, order);
+	if (r < 0) {
+		pr_info("can't find extent\n");
+		goto unlock;
+	}
+
+	__free_space(ns, addr, order);
+
+unlock:
+	mutex_unlock(&only_set->lock);
+}
+EXPORT_SYMBOL_GPL(bch_nvm_free_pages);
+
+
 void *bch_nvm_alloc_pages(int order, const char *owner_uuid)
 {
 	void *kaddr = NULL;
@@ -276,7 +405,6 @@ static int init_owner_info(struct bch_nvm_namespace *ns)
 		for (j = 0; j < only_set->total_namespaces_nr; j++) {
 			if (!only_set->nss[j] || !owner_head->recs[j])
 				continue;
-
 			nvm_pgalloc_recs = (struct bch_nvm_pgalloc_recs *)
 					((long)owner_head->recs[j] + ns->kaddr);
 			if (memcmp(nvm_pgalloc_recs->magic, bch_nvm_pages_pgalloc_magic, 16)) {
@@ -348,7 +476,7 @@ static void init_nvm_free_space(struct bch_nvm_namespace *ns)
 {
 	unsigned int start, end, i;
 	struct page *page;
-	long long pages;
+	u64 pages;
 	pgoff_t pgoff_start;
 
 	bitmap_for_each_clear_region(ns->pages_bitmap, start, end, 0, ns->pages_total) {
@@ -364,9 +492,8 @@ static void init_nvm_free_space(struct bch_nvm_namespace *ns)
 			page = nvm_vaddr_to_page(ns, nvm_pgoff_to_vaddr(ns, pgoff_start));
 			page->index = pgoff_start;
 			set_page_private(page, i);
-			__SetPageBuddy(page);
-			list_add((struct list_head *)&page->zone_device_data, &ns->free_area[i]);
-
+			/* in order to update ns->free */
+			__free_space(ns, nvm_pgoff_to_vaddr(ns, pgoff_start), i);
 			pgoff_start += 1 << i;
 			pages -= 1 << i;
 		}
@@ -530,7 +657,7 @@ struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
 	ns->page_size = ns->sb.page_size;
 	ns->pages_offset = ns->sb.pages_offset;
 	ns->pages_total = ns->sb.pages_total;
-	ns->free = 0;
+	ns->free = 0; /* increased by __free_space() */
 	ns->bdev = bdev;
 	ns->nvm_set = only_set;
 
diff --git a/drivers/md/bcache/nvm-pages.h b/drivers/md/bcache/nvm-pages.h
index 10157d993126..1bc3129f2482 100644
--- a/drivers/md/bcache/nvm-pages.h
+++ b/drivers/md/bcache/nvm-pages.h
@@ -80,6 +80,7 @@ struct bch_nvm_namespace *bch_register_namespace(const char *dev_path);
 int bch_nvm_init(void);
 void bch_nvm_exit(void);
 void *bch_nvm_alloc_pages(int order, const char *owner_uuid);
+void bch_nvm_free_pages(void *addr, int order, const char *owner_uuid);
 
 #else
 
@@ -98,6 +99,8 @@ static inline void *bch_nvm_alloc_pages(int order, const char *owner_uuid)
 	return NULL;
 }
 
+static inline void bch_nvm_free_pages(void *addr, int order, const char *owner_uuid) { }
+
 #endif /* CONFIG_BCACHE_NVM_PAGES */
 
 #endif /* _BCACHE_NVM_PAGES_H */
-- 
2.17.1