4df27c4d5c
btrfs allows subvolumes and snapshots anywhere in the directory tree. If we snapshot a subvolume that contains a link to other subvolume called subvolA, subvolA can be accessed through both the original subvolume and the snapshot. This is similar to creating hard link to directory, and has the very similar problems. The aim of this patch is enforcing there is only one access point to each subvolume. Only the first directory entry (the one added when the subvolume/snapshot was created) is treated as valid access point. The first directory entry is distinguished by checking root forward reference. If the corresponding root forward reference is missing, we know the entry is not the first one. This patch also adds snapshot/subvolume rename support, the code allows rename subvolume link across subvolumes. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
87 lines
2 KiB
C
87 lines
2 KiB
C
/*
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* Copyright (C) 2008 Red Hat. 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 "disk-io.h"
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int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, u64 offset)
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{
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struct btrfs_path *path;
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struct btrfs_key key;
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int ret = 0;
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key.objectid = BTRFS_ORPHAN_OBJECTID;
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btrfs_set_key_type(&key, BTRFS_ORPHAN_ITEM_KEY);
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key.offset = offset;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
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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_orphan_item(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, u64 offset)
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{
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struct btrfs_path *path;
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struct btrfs_key key;
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int ret = 0;
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key.objectid = BTRFS_ORPHAN_OBJECTID;
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btrfs_set_key_type(&key, BTRFS_ORPHAN_ITEM_KEY);
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key.offset = offset;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
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if (ret)
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goto out;
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ret = btrfs_del_item(trans, root, path);
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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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int btrfs_find_orphan_item(struct btrfs_root *root, u64 offset)
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{
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struct btrfs_path *path;
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struct btrfs_key key;
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int ret;
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key.objectid = BTRFS_ORPHAN_OBJECTID;
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key.type = BTRFS_ORPHAN_ITEM_KEY;
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key.offset = offset;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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btrfs_free_path(path);
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return ret;
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}
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