Btrfs: pretend page cache & commit code

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 89 insertions, 2 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c42dc72706bf..656ace6147a8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -11,6 +11,8 @@
 #include "disk-io.h"
 
 static int allocated_blocks = 0;
+int cache_size = 0;
+int cache_max = 10000;
 
 static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 {
@@ -21,6 +23,25 @@ static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 	return 0;
 }
 
+static int free_some_buffers(struct ctree_root *root)
+{
+	struct list_head *node, *next;
+	struct tree_buffer *b;
+	if (root->cache_size < cache_max)
+		return 0;
+	list_for_each_safe(node, next, &root->cache) {
+		b = list_entry(node, struct tree_buffer, cache);
+		if (b->count == 1) {
+			BUG_ON(!list_empty(&b->dirty));
+			list_del_init(&b->cache);
+			tree_block_release(root, b);
+			if (root->cache_size < cache_max)
+				return 0;
+		}
+	}
+	return 0;
+}
+
 struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
 {
 	struct tree_buffer *buf;
@@ -30,10 +51,14 @@ struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
 		return buf;
 	allocated_blocks++;
 	buf->blocknr = blocknr;
-	buf->count = 1;
+	buf->count = 2;
+	INIT_LIST_HEAD(&buf->dirty);
+	free_some_buffers(root);
 	radix_tree_preload(GFP_KERNEL);
 	ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
 	radix_tree_preload_end();
+	list_add_tail(&buf->cache, &root->cache);
+	root->cache_size++;
 	if (ret) {
 		free(buf);
 		return NULL;
@@ -57,7 +82,6 @@ struct tree_buffer *find_tree_block(struct ctree_root *root, u64 blocknr)
 	return buf;
 }
 
-
 struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
 {
 	loff_t offset = blocknr * CTREE_BLOCKSIZE;
@@ -82,6 +106,24 @@ struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
 	return buf;
 }
 
+int dirty_tree_block(struct ctree_root *root, struct tree_buffer *buf)
+{
+	if (!list_empty(&buf->dirty))
+		return 0;
+	list_add_tail(&buf->dirty, &root->trans);
+	buf->count++;
+	return 0;
+}
+
+int clean_tree_block(struct ctree_root *root, struct tree_buffer *buf)
+{
+	if (!list_empty(&buf->dirty)) {
+		list_del_init(&buf->dirty);
+		tree_block_release(root, buf);
+	}
+	return 0;
+}
+
 int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 {
 	u64 blocknr = buf->blocknr;
@@ -96,9 +138,37 @@ int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 	return 0;
 }
 
+static int __commit_transaction(struct ctree_root *root)
+{
+	struct tree_buffer *b;
+	int ret = 0;
+	int wret;
+	while(!list_empty(&root->trans)) {
+		b = list_entry(root->trans.next, struct tree_buffer, dirty);
+		list_del_init(&b->dirty);
+		wret = write_tree_block(root, b);
+		if (wret)
+			ret = wret;
+		tree_block_release(root, b);
+	}
+	return ret;
+}
+
+int commit_transaction(struct ctree_root *root)
+{
+	int ret;
+	ret = __commit_transaction(root);
+	if (!ret && root != root->extent_root)
+		ret = __commit_transaction(root->extent_root);
+	BUG_ON(ret);
+	return ret;
+}
+
 static int __setup_root(struct ctree_root *root, struct ctree_root *extent_root,
 			struct ctree_root_info *info, int fp)
 {
+	INIT_LIST_HEAD(&root->trans);
+	INIT_LIST_HEAD(&root->cache);
 	root->fp = fp;
 	root->node = NULL;
 	root->node = read_tree_block(root, info->tree_root);
@@ -157,8 +227,23 @@ int write_ctree_super(struct ctree_root *root, struct ctree_super_block *s)
 	return 0;
 }
 
+static int drop_cache(struct ctree_root *root)
+{
+	while(!list_empty(&root->cache)) {
+		struct tree_buffer *b = list_entry(root->cache.next,
+						   struct tree_buffer, cache);
+		list_del_init(&b->cache);
+		tree_block_release(root, b);
+	}
+	return 0;
+}
 int close_ctree(struct ctree_root *root)
 {
+	drop_cache(root->extent_root);
+	drop_cache(root);
+	BUG_ON(!list_empty(&root->trans));
+	BUG_ON(!list_empty(&root->extent_root->trans));
+
 	close(root->fp);
 	if (root->node)
 		tree_block_release(root, root->node);
@@ -182,6 +267,8 @@ void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
 		free(buf);
 		BUG_ON(allocated_blocks == 0);
 		allocated_blocks--;
+		BUG_ON(root->cache_size == 0);
+		root->cache_size--;
 	}
 }