v4.19.13 snapshot.
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
new file mode 100644
index 0000000..65bda06
--- /dev/null
+++ b/fs/btrfs/root-tree.c
@@ -0,0 +1,494 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/uuid.h>
+#include "ctree.h"
+#include "transaction.h"
+#include "disk-io.h"
+#include "print-tree.h"
+
+/*
+ * Read a root item from the tree. In case we detect a root item smaller then
+ * sizeof(root_item), we know it's an old version of the root structure and
+ * initialize all new fields to zero. The same happens if we detect mismatching
+ * generation numbers as then we know the root was once mounted with an older
+ * kernel that was not aware of the root item structure change.
+ */
+static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
+ struct btrfs_root_item *item)
+{
+ uuid_le uuid;
+ int len;
+ int need_reset = 0;
+
+ len = btrfs_item_size_nr(eb, slot);
+ read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
+ min_t(int, len, (int)sizeof(*item)));
+ if (len < sizeof(*item))
+ need_reset = 1;
+ if (!need_reset && btrfs_root_generation(item)
+ != btrfs_root_generation_v2(item)) {
+ if (btrfs_root_generation_v2(item) != 0) {
+ btrfs_warn(eb->fs_info,
+ "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
+ }
+ need_reset = 1;
+ }
+ if (need_reset) {
+ memset(&item->generation_v2, 0,
+ sizeof(*item) - offsetof(struct btrfs_root_item,
+ generation_v2));
+
+ uuid_le_gen(&uuid);
+ memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
+ }
+}
+
+/*
+ * btrfs_find_root - lookup the root by the key.
+ * root: the root of the root tree
+ * search_key: the key to search
+ * path: the path we search
+ * root_item: the root item of the tree we look for
+ * root_key: the root key of the tree we look for
+ *
+ * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
+ * of the search key, just lookup the root with the highest offset for a
+ * given objectid.
+ *
+ * If we find something return 0, otherwise > 0, < 0 on error.
+ */
+int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
+ struct btrfs_path *path, struct btrfs_root_item *root_item,
+ struct btrfs_key *root_key)
+{
+ struct btrfs_key found_key;
+ struct extent_buffer *l;
+ int ret;
+ int slot;
+
+ ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
+ if (ret < 0)
+ return ret;
+
+ if (search_key->offset != -1ULL) { /* the search key is exact */
+ if (ret > 0)
+ goto out;
+ } else {
+ BUG_ON(ret == 0); /* Logical error */
+ if (path->slots[0] == 0)
+ goto out;
+ path->slots[0]--;
+ ret = 0;
+ }
+
+ l = path->nodes[0];
+ slot = path->slots[0];
+
+ btrfs_item_key_to_cpu(l, &found_key, slot);
+ if (found_key.objectid != search_key->objectid ||
+ found_key.type != BTRFS_ROOT_ITEM_KEY) {
+ ret = 1;
+ goto out;
+ }
+
+ if (root_item)
+ btrfs_read_root_item(l, slot, root_item);
+ if (root_key)
+ memcpy(root_key, &found_key, sizeof(found_key));
+out:
+ btrfs_release_path(path);
+ return ret;
+}
+
+void btrfs_set_root_node(struct btrfs_root_item *item,
+ struct extent_buffer *node)
+{
+ btrfs_set_root_bytenr(item, node->start);
+ btrfs_set_root_level(item, btrfs_header_level(node));
+ btrfs_set_root_generation(item, btrfs_header_generation(node));
+}
+
+/*
+ * copy the data in 'item' into the btree
+ */
+int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
+ *root, struct btrfs_key *key, struct btrfs_root_item
+ *item)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_path *path;
+ struct extent_buffer *l;
+ int ret;
+ int slot;
+ unsigned long ptr;
+ u32 old_len;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = btrfs_search_slot(trans, root, key, path, 0, 1);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+
+ if (ret != 0) {
+ btrfs_print_leaf(path->nodes[0]);
+ btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
+ key->objectid, key->type, key->offset);
+ BUG_ON(1);
+ }
+
+ l = path->nodes[0];
+ slot = path->slots[0];
+ ptr = btrfs_item_ptr_offset(l, slot);
+ old_len = btrfs_item_size_nr(l, slot);
+
+ /*
+ * If this is the first time we update the root item which originated
+ * from an older kernel, we need to enlarge the item size to make room
+ * for the added fields.
+ */
+ if (old_len < sizeof(*item)) {
+ btrfs_release_path(path);
+ ret = btrfs_search_slot(trans, root, key, path,
+ -1, 1);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+
+ ret = btrfs_del_item(trans, root, path);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+ btrfs_release_path(path);
+ ret = btrfs_insert_empty_item(trans, root, path,
+ key, sizeof(*item));
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+ l = path->nodes[0];
+ slot = path->slots[0];
+ ptr = btrfs_item_ptr_offset(l, slot);
+ }
+
+ /*
+ * Update generation_v2 so at the next mount we know the new root
+ * fields are valid.
+ */
+ btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
+
+ write_extent_buffer(l, item, ptr, sizeof(*item));
+ btrfs_mark_buffer_dirty(path->nodes[0]);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+ const struct btrfs_key *key, struct btrfs_root_item *item)
+{
+ /*
+ * Make sure generation v1 and v2 match. See update_root for details.
+ */
+ btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
+ return btrfs_insert_item(trans, root, key, item, sizeof(*item));
+}
+
+int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ struct extent_buffer *leaf;
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_key root_key;
+ struct btrfs_root *root;
+ int err = 0;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = BTRFS_ORPHAN_OBJECTID;
+ key.type = BTRFS_ORPHAN_ITEM_KEY;
+ key.offset = 0;
+
+ root_key.type = BTRFS_ROOT_ITEM_KEY;
+ root_key.offset = (u64)-1;
+
+ while (1) {
+ ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
+ if (ret < 0) {
+ err = ret;
+ break;
+ }
+
+ leaf = path->nodes[0];
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(tree_root, path);
+ if (ret < 0)
+ err = ret;
+ if (ret != 0)
+ break;
+ leaf = path->nodes[0];
+ }
+
+ btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+ btrfs_release_path(path);
+
+ if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
+ key.type != BTRFS_ORPHAN_ITEM_KEY)
+ break;
+
+ root_key.objectid = key.offset;
+ key.offset++;
+
+ /*
+ * The root might have been inserted already, as before we look
+ * for orphan roots, log replay might have happened, which
+ * triggers a transaction commit and qgroup accounting, which
+ * in turn reads and inserts fs roots while doing backref
+ * walking.
+ */
+ root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
+ if (root) {
+ WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
+ &root->state));
+ if (btrfs_root_refs(&root->root_item) == 0)
+ btrfs_add_dead_root(root);
+ continue;
+ }
+
+ root = btrfs_read_fs_root(tree_root, &root_key);
+ err = PTR_ERR_OR_ZERO(root);
+ if (err && err != -ENOENT) {
+ break;
+ } else if (err == -ENOENT) {
+ struct btrfs_trans_handle *trans;
+
+ btrfs_release_path(path);
+
+ trans = btrfs_join_transaction(tree_root);
+ if (IS_ERR(trans)) {
+ err = PTR_ERR(trans);
+ btrfs_handle_fs_error(fs_info, err,
+ "Failed to start trans to delete orphan item");
+ break;
+ }
+ err = btrfs_del_orphan_item(trans, tree_root,
+ root_key.objectid);
+ btrfs_end_transaction(trans);
+ if (err) {
+ btrfs_handle_fs_error(fs_info, err,
+ "Failed to delete root orphan item");
+ break;
+ }
+ continue;
+ }
+
+ err = btrfs_init_fs_root(root);
+ if (err) {
+ btrfs_free_fs_root(root);
+ break;
+ }
+
+ set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
+
+ err = btrfs_insert_fs_root(fs_info, root);
+ if (err) {
+ BUG_ON(err == -EEXIST);
+ btrfs_free_fs_root(root);
+ break;
+ }
+
+ if (btrfs_root_refs(&root->root_item) == 0)
+ btrfs_add_dead_root(root);
+ }
+
+ btrfs_free_path(path);
+ return err;
+}
+
+/* drop the root item for 'key' from the tree root */
+int btrfs_del_root(struct btrfs_trans_handle *trans,
+ const struct btrfs_key *key)
+{
+ struct btrfs_root *root = trans->fs_info->tree_root;
+ struct btrfs_path *path;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ ret = btrfs_search_slot(trans, root, key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+
+ BUG_ON(ret != 0);
+
+ ret = btrfs_del_item(trans, root, path);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
+ u64 ref_id, u64 dirid, u64 *sequence, const char *name,
+ int name_len)
+
+{
+ struct btrfs_root *tree_root = trans->fs_info->tree_root;
+ struct btrfs_path *path;
+ struct btrfs_root_ref *ref;
+ struct extent_buffer *leaf;
+ struct btrfs_key key;
+ unsigned long ptr;
+ int err = 0;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = root_id;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = ref_id;
+again:
+ ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
+ BUG_ON(ret < 0);
+ if (ret == 0) {
+ leaf = path->nodes[0];
+ ref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_root_ref);
+
+ WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
+ WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
+ ptr = (unsigned long)(ref + 1);
+ WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
+ *sequence = btrfs_root_ref_sequence(leaf, ref);
+
+ ret = btrfs_del_item(trans, tree_root, path);
+ if (ret) {
+ err = ret;
+ goto out;
+ }
+ } else
+ err = -ENOENT;
+
+ if (key.type == BTRFS_ROOT_BACKREF_KEY) {
+ btrfs_release_path(path);
+ key.objectid = ref_id;
+ key.type = BTRFS_ROOT_REF_KEY;
+ key.offset = root_id;
+ goto again;
+ }
+
+out:
+ btrfs_free_path(path);
+ return err;
+}
+
+/*
+ * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
+ * or BTRFS_ROOT_BACKREF_KEY.
+ *
+ * The dirid, sequence, name and name_len refer to the directory entry
+ * that is referencing the root.
+ *
+ * For a forward ref, the root_id is the id of the tree referencing
+ * the root and ref_id is the id of the subvol or snapshot.
+ *
+ * For a back ref the root_id is the id of the subvol or snapshot and
+ * ref_id is the id of the tree referencing it.
+ *
+ * Will return 0, -ENOMEM, or anything from the CoW path
+ */
+int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
+ u64 ref_id, u64 dirid, u64 sequence, const char *name,
+ int name_len)
+{
+ struct btrfs_root *tree_root = trans->fs_info->tree_root;
+ struct btrfs_key key;
+ int ret;
+ struct btrfs_path *path;
+ struct btrfs_root_ref *ref;
+ struct extent_buffer *leaf;
+ unsigned long ptr;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = root_id;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = ref_id;
+again:
+ ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
+ sizeof(*ref) + name_len);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ btrfs_free_path(path);
+ return ret;
+ }
+
+ leaf = path->nodes[0];
+ ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
+ btrfs_set_root_ref_dirid(leaf, ref, dirid);
+ btrfs_set_root_ref_sequence(leaf, ref, sequence);
+ btrfs_set_root_ref_name_len(leaf, ref, name_len);
+ ptr = (unsigned long)(ref + 1);
+ write_extent_buffer(leaf, name, ptr, name_len);
+ btrfs_mark_buffer_dirty(leaf);
+
+ if (key.type == BTRFS_ROOT_BACKREF_KEY) {
+ btrfs_release_path(path);
+ key.objectid = ref_id;
+ key.type = BTRFS_ROOT_REF_KEY;
+ key.offset = root_id;
+ goto again;
+ }
+
+ btrfs_free_path(path);
+ return 0;
+}
+
+/*
+ * Old btrfs forgets to init root_item->flags and root_item->byte_limit
+ * for subvolumes. To work around this problem, we steal a bit from
+ * root_item->inode_item->flags, and use it to indicate if those fields
+ * have been properly initialized.
+ */
+void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
+{
+ u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
+
+ if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
+ inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
+ btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
+ btrfs_set_root_flags(root_item, 0);
+ btrfs_set_root_limit(root_item, 0);
+ }
+}
+
+void btrfs_update_root_times(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ struct btrfs_root_item *item = &root->root_item;
+ struct timespec64 ct;
+
+ ktime_get_real_ts64(&ct);
+ spin_lock(&root->root_item_lock);
+ btrfs_set_root_ctransid(item, trans->transid);
+ btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
+ btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
+ spin_unlock(&root->root_item_lock);
+}