Root/fs/btrfs/inode-item.c

1/*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include "ctree.h"
20#include "disk-io.h"
21#include "transaction.h"
22
23static int find_name_in_backref(struct btrfs_path *path, const char *name,
24             int name_len, struct btrfs_inode_ref **ref_ret)
25{
26    struct extent_buffer *leaf;
27    struct btrfs_inode_ref *ref;
28    unsigned long ptr;
29    unsigned long name_ptr;
30    u32 item_size;
31    u32 cur_offset = 0;
32    int len;
33
34    leaf = path->nodes[0];
35    item_size = btrfs_item_size_nr(leaf, path->slots[0]);
36    ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
37    while (cur_offset < item_size) {
38        ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
39        len = btrfs_inode_ref_name_len(leaf, ref);
40        name_ptr = (unsigned long)(ref + 1);
41        cur_offset += len + sizeof(*ref);
42        if (len != name_len)
43            continue;
44        if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
45            *ref_ret = ref;
46            return 1;
47        }
48    }
49    return 0;
50}
51
52int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
53               struct btrfs_root *root,
54               const char *name, int name_len,
55               u64 inode_objectid, u64 ref_objectid, u64 *index)
56{
57    struct btrfs_path *path;
58    struct btrfs_key key;
59    struct btrfs_inode_ref *ref;
60    struct extent_buffer *leaf;
61    unsigned long ptr;
62    unsigned long item_start;
63    u32 item_size;
64    u32 sub_item_len;
65    int ret;
66    int del_len = name_len + sizeof(*ref);
67
68    key.objectid = inode_objectid;
69    key.offset = ref_objectid;
70    btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
71
72    path = btrfs_alloc_path();
73    if (!path)
74        return -ENOMEM;
75
76    path->leave_spinning = 1;
77
78    ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
79    if (ret > 0) {
80        ret = -ENOENT;
81        goto out;
82    } else if (ret < 0) {
83        goto out;
84    }
85    if (!find_name_in_backref(path, name, name_len, &ref)) {
86        ret = -ENOENT;
87        goto out;
88    }
89    leaf = path->nodes[0];
90    item_size = btrfs_item_size_nr(leaf, path->slots[0]);
91
92    if (index)
93        *index = btrfs_inode_ref_index(leaf, ref);
94
95    if (del_len == item_size) {
96        ret = btrfs_del_item(trans, root, path);
97        goto out;
98    }
99    ptr = (unsigned long)ref;
100    sub_item_len = name_len + sizeof(*ref);
101    item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
102    memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
103                  item_size - (ptr + sub_item_len - item_start));
104    ret = btrfs_truncate_item(trans, root, path,
105                  item_size - sub_item_len, 1);
106    BUG_ON(ret);
107out:
108    btrfs_free_path(path);
109    return ret;
110}
111
112int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
113               struct btrfs_root *root,
114               const char *name, int name_len,
115               u64 inode_objectid, u64 ref_objectid, u64 index)
116{
117    struct btrfs_path *path;
118    struct btrfs_key key;
119    struct btrfs_inode_ref *ref;
120    unsigned long ptr;
121    int ret;
122    int ins_len = name_len + sizeof(*ref);
123
124    key.objectid = inode_objectid;
125    key.offset = ref_objectid;
126    btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
127
128    path = btrfs_alloc_path();
129    if (!path)
130        return -ENOMEM;
131
132    path->leave_spinning = 1;
133    ret = btrfs_insert_empty_item(trans, root, path, &key,
134                      ins_len);
135    if (ret == -EEXIST) {
136        u32 old_size;
137
138        if (find_name_in_backref(path, name, name_len, &ref))
139            goto out;
140
141        old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
142        ret = btrfs_extend_item(trans, root, path, ins_len);
143        BUG_ON(ret);
144        ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
145                     struct btrfs_inode_ref);
146        ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
147        btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
148        btrfs_set_inode_ref_index(path->nodes[0], ref, index);
149        ptr = (unsigned long)(ref + 1);
150        ret = 0;
151    } else if (ret < 0) {
152        if (ret == -EOVERFLOW)
153            ret = -EMLINK;
154        goto out;
155    } else {
156        ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
157                     struct btrfs_inode_ref);
158        btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
159        btrfs_set_inode_ref_index(path->nodes[0], ref, index);
160        ptr = (unsigned long)(ref + 1);
161    }
162    write_extent_buffer(path->nodes[0], name, ptr, name_len);
163    btrfs_mark_buffer_dirty(path->nodes[0]);
164
165out:
166    btrfs_free_path(path);
167    return ret;
168}
169
170int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
171                 struct btrfs_root *root,
172                 struct btrfs_path *path, u64 objectid)
173{
174    struct btrfs_key key;
175    int ret;
176    key.objectid = objectid;
177    btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
178    key.offset = 0;
179
180    ret = btrfs_insert_empty_item(trans, root, path, &key,
181                      sizeof(struct btrfs_inode_item));
182    return ret;
183}
184
185int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
186               *root, struct btrfs_path *path,
187               struct btrfs_key *location, int mod)
188{
189    int ins_len = mod < 0 ? -1 : 0;
190    int cow = mod != 0;
191    int ret;
192    int slot;
193    struct extent_buffer *leaf;
194    struct btrfs_key found_key;
195
196    ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
197    if (ret > 0 && btrfs_key_type(location) == BTRFS_ROOT_ITEM_KEY &&
198        location->offset == (u64)-1 && path->slots[0] != 0) {
199        slot = path->slots[0] - 1;
200        leaf = path->nodes[0];
201        btrfs_item_key_to_cpu(leaf, &found_key, slot);
202        if (found_key.objectid == location->objectid &&
203            btrfs_key_type(&found_key) == btrfs_key_type(location)) {
204            path->slots[0]--;
205            return 0;
206        }
207    }
208    return ret;
209}
210

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