Introduce a new function, btrfs_create_tree(), to create an empty tree.
Currently, there is only one caller to create new tree, namely
data reloc tree in mkfs.
However it's copying fs tree to create a new root.
This copy fs tree method is not a good idea if we only need an empty
tree.
So here introduce a new function, btrfs_create_tree() to create new
tree.
Which will handle the following things:
1) New tree root leaf
Using generic tree allocation
2) New root item in tree root
3) Modify special tree root pointers in fs_info
Only quota_root is supported yet, but can be expended easily
This patch provides the basis to implement quota support in mkfs.
Signed-off-by: Qu Wenruo <w...@suse.com>
---
ctree.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
ctree.h | 2 ++
2 files changed, 111 insertions(+)
diff --git a/ctree.c b/ctree.c
index e26a1c29bb75..4ff1e1d22e0e 100644
--- a/ctree.c
+++ b/ctree.c
@@ -23,6 +23,7 @@
#include "internal.h"
#include "sizes.h"
#include "messages.h"
+#include "utils.h"
static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level);
@@ -137,6 +138,114 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
return 0;
}
+/*
+ * Create a new tree root, with root objectid set to @objectid.
+ *
+ * NOTE: Doesn't support tree with non-zero offset, like tree reloc tree.
+ */
+int btrfs_create_root(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 objectid)
+{
+ struct extent_buffer *node;
+ struct btrfs_root *new_root;
+ struct btrfs_disk_key disk_key;
+ struct btrfs_key location;
+ struct btrfs_root_item root_item = { 0 };
+ int ret;
+
+ new_root = malloc(sizeof(*new_root));
+ if (!new_root)
+ return -ENOMEM;
+
+ btrfs_setup_root(new_root, fs_info, objectid);
+ if (!is_fstree(objectid))
+ new_root->track_dirty = 1;
+ add_root_to_dirty_list(new_root);
+
+ new_root->objectid = objectid;
+ new_root->root_key.objectid = objectid;
+ new_root->root_key.type = BTRFS_ROOT_ITEM_KEY;
+ new_root->root_key.offset = 0;
+
+ node = btrfs_alloc_free_block(trans, new_root, fs_info->nodesize,
+ objectid, &disk_key, 0, 0, 0);
+ if (IS_ERR(node)) {
+ ret = PTR_ERR(node);
+ error("failed to create root node for tree %llu: %d (%s)",
+ objectid, ret, strerror(-ret));
+ return ret;
+ }
+ new_root->node = node;
+
+ btrfs_set_header_generation(node, trans->transid);
+ btrfs_set_header_backref_rev(node, BTRFS_MIXED_BACKREF_REV);
+ btrfs_clear_header_flag(node, BTRFS_HEADER_FLAG_RELOC |
+ BTRFS_HEADER_FLAG_WRITTEN);
+ btrfs_set_header_owner(node, objectid);
+ btrfs_set_header_nritems(node, 0);
+ btrfs_set_header_level(node, 0);
+ write_extent_buffer(node, fs_info->fsid, btrfs_header_fsid(),
+ BTRFS_FSID_SIZE);
+ ret = btrfs_inc_ref(trans, new_root, node, 0);
+ if (ret < 0)
+ goto free;
+
+ /*
+ * Special tree roots may need to modify pointers in @fs_info
+ * Only quota is supported yet.
+ */
+ switch (objectid) {
+ case BTRFS_QUOTA_TREE_OBJECTID:
+ if (fs_info->quota_root) {
+ error("quota root already exists");
+ ret = -EEXIST;
+ goto free;
+ }
+ fs_info->quota_root = new_root;
+ fs_info->quota_enabled = 1;
+ break;
+ /*
+ * Essential trees can't be created by this function, yet.
+ * As we expect such skeleton exists, or a lot of functions like
+ * btrfs_alloc_free_block() doesn't work at all
+ */
+ case BTRFS_ROOT_TREE_OBJECTID:
+ case BTRFS_EXTENT_TREE_OBJECTID:
+ case BTRFS_CHUNK_TREE_OBJECTID:
+ case BTRFS_FS_TREE_OBJECTID:
+ ret = -EEXIST;
+ goto free;
+ default:
+ /* Subvolume trees don't need special handles */
+ if (is_fstree(objectid))
+ break;
+ /* Other special trees are not supported yet */
+ ret = -ENOTTY;
+ goto free;
+ }
+ btrfs_mark_buffer_dirty(node);
+ btrfs_set_root_bytenr(&root_item, btrfs_header_bytenr(node));
+ btrfs_set_root_level(&root_item, 0);
+ btrfs_set_root_generation(&root_item, trans->transid);
+ btrfs_set_root_dirid(&root_item, 0);
+ btrfs_set_root_refs(&root_item, 1);
+ btrfs_set_root_used(&root_item, fs_info->nodesize);
+ location.objectid = objectid;
+ location.type = BTRFS_ROOT_ITEM_KEY;
+ location.offset = 0;
+
+ ret = btrfs_insert_root(trans, fs_info->tree_root, &location,
+ &root_item);
+ if (ret < 0)
+ goto free;
+ return ret;
+
+free:
+ free_extent_buffer(node);
+ free(new_root);
+ return ret;
+}
+
/*
* check if the tree block can be shared by multiple trees
*/
diff --git a/ctree.h b/ctree.h
index cf99df1c90a8..b80771762575 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2606,6 +2606,8 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer **cow_ret, u64 new_root_objectid);
+int btrfs_create_root(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 objectid);
int btrfs_extend_item(struct btrfs_root *root, struct btrfs_path *path,
u32 data_size);
int btrfs_truncate_item(struct btrfs_root *root, struct btrfs_path *path,
--
2.17.0
--
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