Root/fs/btrfs/root-tree.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 "transaction.h"
21#include "disk-io.h"
22#include "print-tree.h"
23
24/*
25 * search forward for a root, starting with objectid 'search_start'
26 * if a root key is found, the objectid we find is filled into 'found_objectid'
27 * and 0 is returned. < 0 is returned on error, 1 if there is nothing
28 * left in the tree.
29 */
30int btrfs_search_root(struct btrfs_root *root, u64 search_start,
31              u64 *found_objectid)
32{
33    struct btrfs_path *path;
34    struct btrfs_key search_key;
35    int ret;
36
37    root = root->fs_info->tree_root;
38    search_key.objectid = search_start;
39    search_key.type = (u8)-1;
40    search_key.offset = (u64)-1;
41
42    path = btrfs_alloc_path();
43    BUG_ON(!path);
44again:
45    ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
46    if (ret < 0)
47        goto out;
48    if (ret == 0) {
49        ret = 1;
50        goto out;
51    }
52    if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
53        ret = btrfs_next_leaf(root, path);
54        if (ret)
55            goto out;
56    }
57    btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
58    if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
59        search_key.offset++;
60        btrfs_release_path(root, path);
61        goto again;
62    }
63    ret = 0;
64    *found_objectid = search_key.objectid;
65
66out:
67    btrfs_free_path(path);
68    return ret;
69}
70
71/*
72 * lookup the root with the highest offset for a given objectid. The key we do
73 * find is copied into 'key'. If we find something return 0, otherwise 1, < 0
74 * on error.
75 */
76int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
77            struct btrfs_root_item *item, struct btrfs_key *key)
78{
79    struct btrfs_path *path;
80    struct btrfs_key search_key;
81    struct btrfs_key found_key;
82    struct extent_buffer *l;
83    int ret;
84    int slot;
85
86    search_key.objectid = objectid;
87    search_key.type = BTRFS_ROOT_ITEM_KEY;
88    search_key.offset = (u64)-1;
89
90    path = btrfs_alloc_path();
91    BUG_ON(!path);
92    ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
93    if (ret < 0)
94        goto out;
95
96    BUG_ON(ret == 0);
97    if (path->slots[0] == 0) {
98        ret = 1;
99        goto out;
100    }
101    l = path->nodes[0];
102    slot = path->slots[0] - 1;
103    btrfs_item_key_to_cpu(l, &found_key, slot);
104    if (found_key.objectid != objectid ||
105        found_key.type != BTRFS_ROOT_ITEM_KEY) {
106        ret = 1;
107        goto out;
108    }
109    if (item)
110        read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
111                   sizeof(*item));
112    if (key)
113        memcpy(key, &found_key, sizeof(found_key));
114    ret = 0;
115out:
116    btrfs_free_path(path);
117    return ret;
118}
119
120int btrfs_set_root_node(struct btrfs_root_item *item,
121            struct extent_buffer *node)
122{
123    btrfs_set_root_bytenr(item, node->start);
124    btrfs_set_root_level(item, btrfs_header_level(node));
125    btrfs_set_root_generation(item, btrfs_header_generation(node));
126    return 0;
127}
128
129/*
130 * copy the data in 'item' into the btree
131 */
132int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
133              *root, struct btrfs_key *key, struct btrfs_root_item
134              *item)
135{
136    struct btrfs_path *path;
137    struct extent_buffer *l;
138    int ret;
139    int slot;
140    unsigned long ptr;
141
142    path = btrfs_alloc_path();
143    BUG_ON(!path);
144    ret = btrfs_search_slot(trans, root, key, path, 0, 1);
145    if (ret < 0)
146        goto out;
147
148    if (ret != 0) {
149        btrfs_print_leaf(root, path->nodes[0]);
150        printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
151               (unsigned long long)key->objectid, key->type,
152               (unsigned long long)key->offset);
153        BUG_ON(1);
154    }
155
156    l = path->nodes[0];
157    slot = path->slots[0];
158    ptr = btrfs_item_ptr_offset(l, slot);
159    write_extent_buffer(l, item, ptr, sizeof(*item));
160    btrfs_mark_buffer_dirty(path->nodes[0]);
161out:
162    btrfs_free_path(path);
163    return ret;
164}
165
166int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
167              *root, struct btrfs_key *key, struct btrfs_root_item
168              *item)
169{
170    int ret;
171    ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
172    return ret;
173}
174
175/*
176 * at mount time we want to find all the old transaction snapshots that were in
177 * the process of being deleted if we crashed. This is any root item with an
178 * offset lower than the latest root. They need to be queued for deletion to
179 * finish what was happening when we crashed.
180 */
181int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
182{
183    struct btrfs_root *dead_root;
184    struct btrfs_item *item;
185    struct btrfs_root_item *ri;
186    struct btrfs_key key;
187    struct btrfs_key found_key;
188    struct btrfs_path *path;
189    int ret;
190    u32 nritems;
191    struct extent_buffer *leaf;
192    int slot;
193
194    key.objectid = objectid;
195    btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
196    key.offset = 0;
197    path = btrfs_alloc_path();
198    if (!path)
199        return -ENOMEM;
200
201again:
202    ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
203    if (ret < 0)
204        goto err;
205    while (1) {
206        leaf = path->nodes[0];
207        nritems = btrfs_header_nritems(leaf);
208        slot = path->slots[0];
209        if (slot >= nritems) {
210            ret = btrfs_next_leaf(root, path);
211            if (ret)
212                break;
213            leaf = path->nodes[0];
214            nritems = btrfs_header_nritems(leaf);
215            slot = path->slots[0];
216        }
217        item = btrfs_item_nr(leaf, slot);
218        btrfs_item_key_to_cpu(leaf, &key, slot);
219        if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
220            goto next;
221
222        if (key.objectid < objectid)
223            goto next;
224
225        if (key.objectid > objectid)
226            break;
227
228        ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
229        if (btrfs_disk_root_refs(leaf, ri) != 0)
230            goto next;
231
232        memcpy(&found_key, &key, sizeof(key));
233        key.offset++;
234        btrfs_release_path(root, path);
235        dead_root =
236            btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
237                            &found_key);
238        if (IS_ERR(dead_root)) {
239            ret = PTR_ERR(dead_root);
240            goto err;
241        }
242
243        ret = btrfs_add_dead_root(dead_root);
244        if (ret)
245            goto err;
246        goto again;
247next:
248        slot++;
249        path->slots[0]++;
250    }
251    ret = 0;
252err:
253    btrfs_free_path(path);
254    return ret;
255}
256
257int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
258{
259    struct extent_buffer *leaf;
260    struct btrfs_path *path;
261    struct btrfs_key key;
262    int err = 0;
263    int ret;
264
265    path = btrfs_alloc_path();
266    if (!path)
267        return -ENOMEM;
268
269    key.objectid = BTRFS_ORPHAN_OBJECTID;
270    key.type = BTRFS_ORPHAN_ITEM_KEY;
271    key.offset = 0;
272
273    while (1) {
274        ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
275        if (ret < 0) {
276            err = ret;
277            break;
278        }
279
280        leaf = path->nodes[0];
281        if (path->slots[0] >= btrfs_header_nritems(leaf)) {
282            ret = btrfs_next_leaf(tree_root, path);
283            if (ret < 0)
284                err = ret;
285            if (ret != 0)
286                break;
287            leaf = path->nodes[0];
288        }
289
290        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
291        btrfs_release_path(tree_root, path);
292
293        if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
294            key.type != BTRFS_ORPHAN_ITEM_KEY)
295            break;
296
297        ret = btrfs_find_dead_roots(tree_root, key.offset);
298        if (ret) {
299            err = ret;
300            break;
301        }
302
303        key.offset++;
304    }
305
306    btrfs_free_path(path);
307    return err;
308}
309
310/* drop the root item for 'key' from 'root' */
311int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
312           struct btrfs_key *key)
313{
314    struct btrfs_path *path;
315    int ret;
316    u32 refs;
317    struct btrfs_root_item *ri;
318    struct extent_buffer *leaf;
319
320    path = btrfs_alloc_path();
321    BUG_ON(!path);
322    ret = btrfs_search_slot(trans, root, key, path, -1, 1);
323    if (ret < 0)
324        goto out;
325
326    BUG_ON(ret != 0);
327    leaf = path->nodes[0];
328    ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
329
330    refs = btrfs_disk_root_refs(leaf, ri);
331    BUG_ON(refs != 0);
332    ret = btrfs_del_item(trans, root, path);
333out:
334    btrfs_free_path(path);
335    return ret;
336}
337
338int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
339               struct btrfs_root *tree_root,
340               u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
341               const char *name, int name_len)
342
343{
344    struct btrfs_path *path;
345    struct btrfs_root_ref *ref;
346    struct extent_buffer *leaf;
347    struct btrfs_key key;
348    unsigned long ptr;
349    int err = 0;
350    int ret;
351
352    path = btrfs_alloc_path();
353    if (!path)
354        return -ENOMEM;
355
356    key.objectid = root_id;
357    key.type = BTRFS_ROOT_BACKREF_KEY;
358    key.offset = ref_id;
359again:
360    ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
361    BUG_ON(ret < 0);
362    if (ret == 0) {
363        leaf = path->nodes[0];
364        ref = btrfs_item_ptr(leaf, path->slots[0],
365                     struct btrfs_root_ref);
366
367        WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
368        WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
369        ptr = (unsigned long)(ref + 1);
370        WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
371        *sequence = btrfs_root_ref_sequence(leaf, ref);
372
373        ret = btrfs_del_item(trans, tree_root, path);
374        BUG_ON(ret);
375    } else
376        err = -ENOENT;
377
378    if (key.type == BTRFS_ROOT_BACKREF_KEY) {
379        btrfs_release_path(tree_root, path);
380        key.objectid = ref_id;
381        key.type = BTRFS_ROOT_REF_KEY;
382        key.offset = root_id;
383        goto again;
384    }
385
386    btrfs_free_path(path);
387    return err;
388}
389
390int btrfs_find_root_ref(struct btrfs_root *tree_root,
391           struct btrfs_path *path,
392           u64 root_id, u64 ref_id)
393{
394    struct btrfs_key key;
395    int ret;
396
397    key.objectid = root_id;
398    key.type = BTRFS_ROOT_REF_KEY;
399    key.offset = ref_id;
400
401    ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
402    return ret;
403}
404
405/*
406 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
407 * or BTRFS_ROOT_BACKREF_KEY.
408 *
409 * The dirid, sequence, name and name_len refer to the directory entry
410 * that is referencing the root.
411 *
412 * For a forward ref, the root_id is the id of the tree referencing
413 * the root and ref_id is the id of the subvol or snapshot.
414 *
415 * For a back ref the root_id is the id of the subvol or snapshot and
416 * ref_id is the id of the tree referencing it.
417 */
418int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
419               struct btrfs_root *tree_root,
420               u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
421               const char *name, int name_len)
422{
423    struct btrfs_key key;
424    int ret;
425    struct btrfs_path *path;
426    struct btrfs_root_ref *ref;
427    struct extent_buffer *leaf;
428    unsigned long ptr;
429
430    path = btrfs_alloc_path();
431    if (!path)
432        return -ENOMEM;
433
434    key.objectid = root_id;
435    key.type = BTRFS_ROOT_BACKREF_KEY;
436    key.offset = ref_id;
437again:
438    ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
439                      sizeof(*ref) + name_len);
440    BUG_ON(ret);
441
442    leaf = path->nodes[0];
443    ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
444    btrfs_set_root_ref_dirid(leaf, ref, dirid);
445    btrfs_set_root_ref_sequence(leaf, ref, sequence);
446    btrfs_set_root_ref_name_len(leaf, ref, name_len);
447    ptr = (unsigned long)(ref + 1);
448    write_extent_buffer(leaf, name, ptr, name_len);
449    btrfs_mark_buffer_dirty(leaf);
450
451    if (key.type == BTRFS_ROOT_BACKREF_KEY) {
452        btrfs_release_path(tree_root, path);
453        key.objectid = ref_id;
454        key.type = BTRFS_ROOT_REF_KEY;
455        key.offset = root_id;
456        goto again;
457    }
458
459    btrfs_free_path(path);
460    return 0;
461}
462

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