Btrfs: tweak the inode-map and free extent search starts on cold mount

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

fs/btrfs/TODO

 * cleanup, add more error checking, get rid of BUG_ONs
 * Fix ENOSPC handling
-* Do checksumming
 * Add block mapping tree (simple dm layer)
 * Make allocator smarter
-* make level a field in header
 * add a block group to struct inode
 * Make directory hashing work on 32 bit
 * Make sure nobh stuff is working properly for cows

fs/btrfs/ctree.h

@@ -238,7 +238,6 @@ struct btrfs_fs_info {
 	struct radix_tree_root pending_del_radix;
 	struct radix_tree_root pinned_radix;
 	u64 last_inode_alloc;
-	u64 last_inode_alloc_dirid;
 	u64 generation;
 	struct btrfs_transaction *running_transaction;
 	struct btrfs_super_block *disk_super;

fs/btrfs/disk-io.c

@@ -311,7 +311,6 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 	fs_info->extent_root = extent_root;
 	fs_info->inode_root = inode_root;
 	fs_info->last_inode_alloc = 0;
-	fs_info->last_inode_alloc_dirid = 0;
 	fs_info->sb = sb;
 	fs_info->btree_inode = new_inode(sb);
 	fs_info->btree_inode->i_ino = 1;

fs/btrfs/extent-tree.c

@@ -339,13 +339,30 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 	int total_needed = num_blocks;
 	int level;
 
+	path = btrfs_alloc_path();
+	ins->flags = 0;
+	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+
 	level = btrfs_header_level(btrfs_buffer_header(root->node));
 	total_needed += (level + 1) * 3;
+	if (root->fs_info->last_insert.objectid == 0 && search_end == (u64)-1) {
+		struct btrfs_disk_key *last_key;
+		btrfs_init_path(path);
+		ins->objectid = (u64)-1;
+		ins->offset = (u64)-1;
+		ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
+		if (ret < 0)
+			goto error;
+		BUG_ON(ret == 0);
+		if (path->slots[0] > 0)
+			path->slots[0]--;
+		l = btrfs_buffer_leaf(path->nodes[0]);
+		last_key = &l->items[path->slots[0]].key;
+		search_start = btrfs_disk_key_objectid(last_key);
+	}
 	if (root->fs_info->last_insert.objectid > search_start)
 		search_start = root->fs_info->last_insert.objectid;
 
-	ins->flags = 0;
-	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 	path = btrfs_alloc_path();
 
 check_failed:

fs/btrfs/inode-map.c

@@ -22,17 +22,31 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
 	struct btrfs_key search_key;
 	u64 search_start = dirid;
 
-	if (fs_root->fs_info->last_inode_alloc_dirid == dirid)
-		search_start = fs_root->fs_info->last_inode_alloc;
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+	search_key.flags = 0;
+	btrfs_set_key_type(&search_key, BTRFS_INODE_MAP_ITEM_KEY);
 
+	search_start = fs_root->fs_info->last_inode_alloc;
+	if (search_start == 0) {
+		struct btrfs_disk_key *last_key;
+		btrfs_init_path(path);
+		search_key.objectid = (u64)-1;
+		search_key.offset = (u64)-1;
+		ret = btrfs_search_slot(trans, root, &search_key, path, 0, 0);
+		if (ret < 0)
+			goto error;
+		BUG_ON(ret == 0);
+		if (path->slots[0] > 0)
+			path->slots[0]--;
+		l = btrfs_buffer_leaf(path->nodes[0]);
+		last_key = &l->items[path->slots[0]].key;
+		search_start = btrfs_disk_key_objectid(last_key);
+	}
 	search_start = max(search_start, BTRFS_FIRST_FREE_OBJECTID);
 	search_key.objectid = search_start;
-	search_key.flags = 0;
-	btrfs_set_key_type(&search_key, BTRFS_INODE_MAP_ITEM_KEY);
 	search_key.offset = 0;
 
-	path = btrfs_alloc_path();
-	BUG_ON(!path);
 	btrfs_init_path(path);
 	start_found = 0;
 	ret = btrfs_search_slot(trans, root, &search_key, path, 0, 0);
@@ -79,7 +93,6 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
 	// FIXME -ENOSPC
 found:
 	root->fs_info->last_inode_alloc = *objectid;
-	root->fs_info->last_inode_alloc_dirid = dirid;
 	btrfs_release_path(root, path);
 	btrfs_free_path(path);
 	BUG_ON(*objectid < search_start);