create a root dir in mkfs

ctree.h

@@ -75,6 +75,7 @@ struct btrfs_super_block {
 	__le64 root;
 	__le64 total_blocks;
 	__le64 blocks_used;
+	__le64 root_dir_objectid;
 } __attribute__ ((__packed__));
 
 /*
@@ -693,6 +694,17 @@ static inline void btrfs_set_super_blocksize(struct btrfs_super_block *s,
 	s->blocksize = cpu_to_le32(val);
 }
 
+static inline u64 btrfs_super_root_dir(struct btrfs_super_block *s)
+{
+	return le64_to_cpu(s->root_dir_objectid);
+}
+
+static inline void btrfs_set_super_root_dir(struct btrfs_super_block *s, u64
+					    val)
+{
+	s->root_dir_objectid = cpu_to_le64(val);
+}
+
 static inline u8 *btrfs_leaf_data(struct btrfs_leaf *l)
 {
 	return (u8 *)l->items;

dir-item.c

@@ -21,7 +21,12 @@ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 	key.objectid = dir;
 	key.flags = 0;
 	btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
-	ret = btrfs_name_hash(name, name_len, &key.offset);
+	if (name_len == 1 && *name == '.')
+		key.offset = 1;
+	else if (name_len == 2 && name[0] == '.' && name[1] == '.')
+		key.offset = 2;
+	else
+		ret = btrfs_name_hash(name, name_len, &key.offset);
 	BUG_ON(ret);
 	btrfs_init_path(&path);
 	data_size = sizeof(*dir_item) + name_len;

disk-io.c

@@ -266,20 +266,25 @@ static int find_and_setup_root(struct btrfs_super_block *super,
 }
 
 struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
+{
+	int fp;
+
+	fp = open(filename, O_CREAT | O_RDWR, 0600);
+	if (fp < 0) {
+		return NULL;
+	}
+	return open_ctree_fd(fp, super);
+}
+
+struct btrfs_root *open_ctree_fd(int fp, struct btrfs_super_block *super)
 {
 	struct btrfs_root *root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *inode_root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
-	int fp;
 	int ret;
 
-	fp = open(filename, O_CREAT | O_RDWR, 0600);
-	if (fp < 0) {
-		free(root);
-		return NULL;
-	}
 	INIT_RADIX_TREE(&fs_info->cache_radix, GFP_KERNEL);
 	INIT_RADIX_TREE(&fs_info->pinned_radix, GFP_KERNEL);
 	INIT_LIST_HEAD(&fs_info->trans);

disk-io.h

@@ -24,6 +24,7 @@ int clean_tree_block(struct btrfs_trans_handle *trans,
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans, struct btrfs_root
 			     *root, struct btrfs_super_block *s);
 struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *s);
+struct btrfs_root *open_ctree_fd(int fp, struct btrfs_super_block *super);
 int close_ctree(struct btrfs_root *root, struct btrfs_super_block *s);
 void btrfs_block_release(struct btrfs_root *root, struct btrfs_buffer *buf);
 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root *root,

mkfs.c

@@ -13,17 +13,73 @@
 #include "radix-tree.h"
 #include "ctree.h"
 #include "disk-io.h"
+#include "transaction.h"
 
 #ifdef __CHECKER__
 #define BLKGETSIZE64 0
 static inline int ioctl(int fd, int define, u64 *size) { return 0; }
 #endif
 
-#if 0
+static int make_root_dir(int fd) {
-#if defined(__linux__) && defined(_IOR) && !defined(BLKGETSIZE64)
+	struct btrfs_root *root;
-#   define BLKGETSIZE64 _IOR(0x12, 114, __u64)
+	struct btrfs_super_block super;
-#endif
+	int ret;
-#endif
+	char buf[8];
+	u64 objectid;
+	struct btrfs_key inode_map;
+	struct btrfs_inode_item inode_item;
+	struct btrfs_trans_handle *trans;
+
+	root = open_ctree_fd(fd, &super);
+
+	if (!root) {
+		fprintf(stderr, "ctree init failed\n");
+		return -1;
+	}
+
+	buf[0] = '.';
+	buf[1] = '.';
+
+	trans = btrfs_start_transaction(root, 1);
+	ret = btrfs_find_free_objectid(trans, root, 1, &objectid);
+	if (ret)
+		goto error;
+
+	inode_map.objectid = objectid;
+	inode_map.flags = 0;
+	inode_map.offset = 0;
+
+	ret = btrfs_insert_inode_map(trans, root, objectid, &inode_map);
+	if (ret)
+		goto error;
+
+	memset(&inode_item, 0, sizeof(inode_item));
+	btrfs_set_inode_generation(&inode_item, root->fs_info->generation);
+	btrfs_set_inode_size(&inode_item, 3);
+	btrfs_set_inode_nlink(&inode_item, 1);
+	btrfs_set_inode_nblocks(&inode_item, 1);
+	btrfs_set_inode_mode(&inode_item, S_IFDIR | 0711);
+
+	btrfs_set_super_root_dir(&super, objectid);
+
+	ret = btrfs_insert_inode(trans, root, objectid, &inode_item);
+	if (ret)
+		goto error;
+	ret = btrfs_insert_dir_item(trans, root, buf, 1, objectid,
+				    objectid, 1);
+	if (ret)
+		goto error;
+	ret = btrfs_insert_dir_item(trans, root, buf, 2, objectid,
+				    objectid, 1);
+	if (ret)
+		goto error;
+	ret = btrfs_commit_transaction(trans, root, &super);
+	if (ret)
+		goto error;
+	ret = close_ctree(root, &super);
+error:
+	return ret;
+}
 
 int mkfs(int fd, u64 num_blocks, u32 blocksize)
 {
@@ -200,6 +256,9 @@ int main(int ac, char **av)
 	int ret;
 	int i;
 	char *buf = malloc(4096);
+
+	radix_tree_init();
+
 	if (ac >= 2) {
 		file = av[1];
 		if (ac == 3) {
@@ -248,6 +307,11 @@ int main(int ac, char **av)
 		fprintf(stderr, "error during mkfs %d\n", ret);
 		exit(1);
 	}
+	ret = make_root_dir(fd);
+	if (ret) {
+		fprintf(stderr, "failed to setup the root directory\n");
+		exit(1);
+	}
 	printf("fs created on %s blocksize %d blocks %Lu\n",
 	       file, 4096, block_count);
 	return 0;

print-tree.c

@@ -34,9 +34,10 @@ void btrfs_print_leaf(struct btrfs_root *root, struct btrfs_leaf *l)
 		switch (type) {
 		case BTRFS_INODE_ITEM_KEY:
 			ii = btrfs_item_ptr(l, i, struct btrfs_inode_item);
-			printf("\t\tinode generation %Lu size %Lu\n",
+			printf("\t\tinode generation %Lu size %Lu mode %o\n",
 			       btrfs_inode_generation(ii),
-			       btrfs_inode_size(ii));
+			       btrfs_inode_size(ii),
+			       btrfs_inode_mode(ii));
 			break;
 		case BTRFS_DIR_ITEM_KEY:
 			di = btrfs_item_ptr(l, i, struct btrfs_dir_item);