fs: btrfs: Crossport open_ctree_fs_info() from btrfs-progs
open_ctree_fs_info() is the main entry point to open btrfs.
This version is a simplfied version of __open_ctree_fd() of btrfs-progs,
the main differences are:
- Parameters on how to specify a block device
Instead of @fd and @path, U-Boot uses blk_desc and disk_partition_t.
- Remove open_ctree flags
There won't be multiple open ctree modes in U-Boot.
Otherwise functions structures are all kept the same.
With open_ctree_fs_info() implemented, also introduce the global
current_fs_info pointer to show the current opened btrfs.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
new file mode 100644
index 0000000..a39ad72
--- /dev/null
+++ b/fs/btrfs/root-tree.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include "ctree.h"
+
+int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
+ struct btrfs_root_item *item, struct btrfs_key *key)
+{
+ struct btrfs_path *path;
+ struct btrfs_key search_key;
+ struct btrfs_key found_key;
+ struct extent_buffer *l;
+ int ret;
+ int slot;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ search_key.objectid = objectid;
+ search_key.type = BTRFS_ROOT_ITEM_KEY;
+ search_key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+ if (path->slots[0] == 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ BUG_ON(ret == 0);
+ l = path->nodes[0];
+ slot = path->slots[0] - 1;
+ btrfs_item_key_to_cpu(l, &found_key, slot);
+ if (found_key.type != BTRFS_ROOT_ITEM_KEY ||
+ found_key.objectid != objectid) {
+ ret = -ENOENT;
+ goto out;
+ }
+ read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
+ sizeof(*item));
+ memcpy(key, &found_key, sizeof(found_key));
+ ret = 0;
+out:
+ btrfs_free_path(path);
+ return ret;
+}