ea9e8b11bd
For a directory tree: /mnt/subvolA/subvolB btrfsctl -s /mnt/subvolA/subvolB /mnt Will create a directory loop with subvolA under subvolB. This commit uses the forward refs for each subvol and snapshot to error out before creating the loop. Signed-off-by: Chris Mason <chris.mason@oracle.com>
368 lines
8.9 KiB
C
368 lines
8.9 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include "ctree.h"
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#include "transaction.h"
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#include "disk-io.h"
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#include "print-tree.h"
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/*
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* search forward for a root, starting with objectid 'search_start'
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* if a root key is found, the objectid we find is filled into 'found_objectid'
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* and 0 is returned. < 0 is returned on error, 1 if there is nothing
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* left in the tree.
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*/
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int btrfs_search_root(struct btrfs_root *root, u64 search_start,
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u64 *found_objectid)
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{
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struct btrfs_path *path;
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struct btrfs_key search_key;
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int ret;
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root = root->fs_info->tree_root;
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search_key.objectid = search_start;
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search_key.type = (u8)-1;
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search_key.offset = (u64)-1;
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path = btrfs_alloc_path();
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BUG_ON(!path);
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again:
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ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
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if (ret < 0)
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goto out;
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if (ret == 0) {
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ret = 1;
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goto out;
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}
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if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
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ret = btrfs_next_leaf(root, path);
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if (ret)
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goto out;
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}
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btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
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if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
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search_key.offset++;
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btrfs_release_path(root, path);
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goto again;
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}
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ret = 0;
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*found_objectid = search_key.objectid;
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out:
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btrfs_free_path(path);
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return ret;
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}
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/*
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* lookup the root with the highest offset for a given objectid. The key we do
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* find is copied into 'key'. If we find something return 0, otherwise 1, < 0
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* on error.
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*/
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int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
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struct btrfs_root_item *item, struct btrfs_key *key)
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{
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struct btrfs_path *path;
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struct btrfs_key search_key;
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struct btrfs_key found_key;
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struct extent_buffer *l;
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int ret;
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int slot;
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search_key.objectid = objectid;
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search_key.type = BTRFS_ROOT_ITEM_KEY;
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search_key.offset = (u64)-1;
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path = btrfs_alloc_path();
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BUG_ON(!path);
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ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
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if (ret < 0)
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goto out;
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BUG_ON(ret == 0);
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l = path->nodes[0];
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BUG_ON(path->slots[0] == 0);
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slot = path->slots[0] - 1;
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btrfs_item_key_to_cpu(l, &found_key, slot);
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if (found_key.objectid != objectid) {
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ret = 1;
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goto out;
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}
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read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
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sizeof(*item));
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memcpy(key, &found_key, sizeof(found_key));
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ret = 0;
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out:
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btrfs_free_path(path);
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return ret;
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}
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/*
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* copy the data in 'item' into the btree
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*/
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int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
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*root, struct btrfs_key *key, struct btrfs_root_item
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*item)
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{
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struct btrfs_path *path;
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struct extent_buffer *l;
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int ret;
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int slot;
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unsigned long ptr;
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path = btrfs_alloc_path();
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BUG_ON(!path);
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ret = btrfs_search_slot(trans, root, key, path, 0, 1);
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if (ret < 0)
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goto out;
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if (ret != 0) {
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btrfs_print_leaf(root, path->nodes[0]);
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printk("unable to update root key %Lu %u %Lu\n",
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key->objectid, key->type, key->offset);
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BUG_ON(1);
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}
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l = path->nodes[0];
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slot = path->slots[0];
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ptr = btrfs_item_ptr_offset(l, slot);
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write_extent_buffer(l, item, ptr, sizeof(*item));
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btrfs_mark_buffer_dirty(path->nodes[0]);
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out:
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btrfs_release_path(root, path);
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btrfs_free_path(path);
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return ret;
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}
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int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
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*root, struct btrfs_key *key, struct btrfs_root_item
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*item)
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{
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int ret;
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ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
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return ret;
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}
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/*
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* at mount time we want to find all the old transaction snapshots that were in
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* the process of being deleted if we crashed. This is any root item with an offset
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* lower than the latest root. They need to be queued for deletion to finish
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* what was happening when we crashed.
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*/
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int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
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struct btrfs_root *latest)
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{
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struct btrfs_root *dead_root;
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struct btrfs_item *item;
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struct btrfs_root_item *ri;
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struct btrfs_key key;
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struct btrfs_key found_key;
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struct btrfs_path *path;
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int ret;
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u32 nritems;
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struct extent_buffer *leaf;
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int slot;
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key.objectid = objectid;
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btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
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key.offset = 0;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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again:
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0)
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goto err;
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while(1) {
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leaf = path->nodes[0];
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nritems = btrfs_header_nritems(leaf);
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slot = path->slots[0];
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if (slot >= nritems) {
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ret = btrfs_next_leaf(root, path);
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if (ret)
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break;
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leaf = path->nodes[0];
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nritems = btrfs_header_nritems(leaf);
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slot = path->slots[0];
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}
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item = btrfs_item_nr(leaf, slot);
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btrfs_item_key_to_cpu(leaf, &key, slot);
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if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
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goto next;
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if (key.objectid < objectid)
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goto next;
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if (key.objectid > objectid)
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break;
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ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
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if (btrfs_disk_root_refs(leaf, ri) != 0)
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goto next;
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memcpy(&found_key, &key, sizeof(key));
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key.offset++;
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btrfs_release_path(root, path);
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dead_root =
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btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
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&found_key);
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if (IS_ERR(dead_root)) {
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ret = PTR_ERR(dead_root);
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goto err;
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}
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if (objectid == BTRFS_TREE_RELOC_OBJECTID)
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ret = btrfs_add_dead_reloc_root(dead_root);
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else
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ret = btrfs_add_dead_root(dead_root, latest);
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if (ret)
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goto err;
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goto again;
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next:
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slot++;
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path->slots[0]++;
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}
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ret = 0;
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err:
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btrfs_free_path(path);
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return ret;
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}
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/* drop the root item for 'key' from 'root' */
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int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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struct btrfs_key *key)
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{
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struct btrfs_path *path;
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int ret;
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u32 refs;
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struct btrfs_root_item *ri;
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struct extent_buffer *leaf;
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path = btrfs_alloc_path();
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BUG_ON(!path);
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ret = btrfs_search_slot(trans, root, key, path, -1, 1);
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if (ret < 0)
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goto out;
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if (ret) {
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btrfs_print_leaf(root, path->nodes[0]);
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printk("failed to del %Lu %u %Lu\n", key->objectid, key->type, key->offset);
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}
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BUG_ON(ret != 0);
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leaf = path->nodes[0];
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ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
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refs = btrfs_disk_root_refs(leaf, ri);
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BUG_ON(refs != 0);
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ret = btrfs_del_item(trans, root, path);
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out:
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btrfs_release_path(root, path);
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btrfs_free_path(path);
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return ret;
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}
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int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
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struct btrfs_root *tree_root,
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u64 root_id, u8 type, u64 ref_id)
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{
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struct btrfs_key key;
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int ret;
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struct btrfs_path *path;
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path = btrfs_alloc_path();
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key.objectid = root_id;
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key.type = type;
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key.offset = ref_id;
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ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
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BUG_ON(ret);
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ret = btrfs_del_item(trans, tree_root, path);
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BUG_ON(ret);
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btrfs_free_path(path);
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return ret;
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}
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int btrfs_find_root_ref(struct btrfs_root *tree_root,
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struct btrfs_path *path,
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u64 root_id, u64 ref_id)
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{
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struct btrfs_key key;
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int ret;
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key.objectid = root_id;
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key.type = BTRFS_ROOT_REF_KEY;
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key.offset = ref_id;
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ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
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return ret;
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}
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/*
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* add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
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* or BTRFS_ROOT_BACKREF_KEY.
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*
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* The dirid, sequence, name and name_len refer to the directory entry
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* that is referencing the root.
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*
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* For a forward ref, the root_id is the id of the tree referencing
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* the root and ref_id is the id of the subvol or snapshot.
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*
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* For a back ref the root_id is the id of the subvol or snapshot and
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* ref_id is the id of the tree referencing it.
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*/
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int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
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struct btrfs_root *tree_root,
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u64 root_id, u8 type, u64 ref_id,
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u64 dirid, u64 sequence,
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const char *name, int name_len)
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{
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struct btrfs_key key;
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int ret;
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struct btrfs_path *path;
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struct btrfs_root_ref *ref;
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struct extent_buffer *leaf;
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unsigned long ptr;
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path = btrfs_alloc_path();
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key.objectid = root_id;
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key.type = type;
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key.offset = ref_id;
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ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
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sizeof(*ref) + name_len);
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BUG_ON(ret);
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leaf = path->nodes[0];
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ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
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btrfs_set_root_ref_dirid(leaf, ref, dirid);
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btrfs_set_root_ref_sequence(leaf, ref, sequence);
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btrfs_set_root_ref_name_len(leaf, ref, name_len);
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ptr = (unsigned long)(ref + 1);
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write_extent_buffer(leaf, name, ptr, name_len);
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btrfs_mark_buffer_dirty(leaf);
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btrfs_free_path(path);
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return ret;
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}
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