Root/fs/btrfs/dir-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 "hash.h"
22#include "transaction.h"
23
24/*
25 * insert a name into a directory, doing overflow properly if there is a hash
26 * collision. data_size indicates how big the item inserted should be. On
27 * success a struct btrfs_dir_item pointer is returned, otherwise it is
28 * an ERR_PTR.
29 *
30 * The name is not copied into the dir item, you have to do that yourself.
31 */
32static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
33                           *trans,
34                           struct btrfs_root *root,
35                           struct btrfs_path *path,
36                           struct btrfs_key *cpu_key,
37                           u32 data_size,
38                           const char *name,
39                           int name_len)
40{
41    int ret;
42    char *ptr;
43    struct btrfs_item *item;
44    struct extent_buffer *leaf;
45
46    ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
47    if (ret == -EEXIST) {
48        struct btrfs_dir_item *di;
49        di = btrfs_match_dir_item_name(root, path, name, name_len);
50        if (di)
51            return ERR_PTR(-EEXIST);
52        ret = btrfs_extend_item(trans, root, path, data_size);
53        WARN_ON(ret > 0);
54    }
55    if (ret < 0)
56        return ERR_PTR(ret);
57    WARN_ON(ret > 0);
58    leaf = path->nodes[0];
59    item = btrfs_item_nr(leaf, path->slots[0]);
60    ptr = btrfs_item_ptr(leaf, path->slots[0], char);
61    BUG_ON(data_size > btrfs_item_size(leaf, item));
62    ptr += btrfs_item_size(leaf, item) - data_size;
63    return (struct btrfs_dir_item *)ptr;
64}
65
66/*
67 * xattrs work a lot like directories, this inserts an xattr item
68 * into the tree
69 */
70int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
71                struct btrfs_root *root,
72                struct btrfs_path *path, u64 objectid,
73                const char *name, u16 name_len,
74                const void *data, u16 data_len)
75{
76    int ret = 0;
77    struct btrfs_dir_item *dir_item;
78    unsigned long name_ptr, data_ptr;
79    struct btrfs_key key, location;
80    struct btrfs_disk_key disk_key;
81    struct extent_buffer *leaf;
82    u32 data_size;
83
84    BUG_ON(name_len + data_len > BTRFS_MAX_XATTR_SIZE(root));
85
86    key.objectid = objectid;
87    btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
88    key.offset = btrfs_name_hash(name, name_len);
89
90    data_size = sizeof(*dir_item) + name_len + data_len;
91    dir_item = insert_with_overflow(trans, root, path, &key, data_size,
92                    name, name_len);
93    /*
94     * FIXME: at some point we should handle xattr's that are larger than
95     * what we can fit in our leaf. We set location to NULL b/c we arent
96     * pointing at anything else, that will change if we store the xattr
97     * data in a separate inode.
98     */
99    BUG_ON(IS_ERR(dir_item));
100    memset(&location, 0, sizeof(location));
101
102    leaf = path->nodes[0];
103    btrfs_cpu_key_to_disk(&disk_key, &location);
104    btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
105    btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
106    btrfs_set_dir_name_len(leaf, dir_item, name_len);
107    btrfs_set_dir_transid(leaf, dir_item, trans->transid);
108    btrfs_set_dir_data_len(leaf, dir_item, data_len);
109    name_ptr = (unsigned long)(dir_item + 1);
110    data_ptr = (unsigned long)((char *)name_ptr + name_len);
111
112    write_extent_buffer(leaf, name, name_ptr, name_len);
113    write_extent_buffer(leaf, data, data_ptr, data_len);
114    btrfs_mark_buffer_dirty(path->nodes[0]);
115
116    return ret;
117}
118
119/*
120 * insert a directory item in the tree, doing all the magic for
121 * both indexes. 'dir' indicates which objectid to insert it into,
122 * 'location' is the key to stuff into the directory item, 'type' is the
123 * type of the inode we're pointing to, and 'index' is the sequence number
124 * to use for the second index (if one is created).
125 */
126int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
127              *root, const char *name, int name_len, u64 dir,
128              struct btrfs_key *location, u8 type, u64 index)
129{
130    int ret = 0;
131    int ret2 = 0;
132    struct btrfs_path *path;
133    struct btrfs_dir_item *dir_item;
134    struct extent_buffer *leaf;
135    unsigned long name_ptr;
136    struct btrfs_key key;
137    struct btrfs_disk_key disk_key;
138    u32 data_size;
139
140    key.objectid = dir;
141    btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
142    key.offset = btrfs_name_hash(name, name_len);
143
144    path = btrfs_alloc_path();
145    path->leave_spinning = 1;
146
147    data_size = sizeof(*dir_item) + name_len;
148    dir_item = insert_with_overflow(trans, root, path, &key, data_size,
149                    name, name_len);
150    if (IS_ERR(dir_item)) {
151        ret = PTR_ERR(dir_item);
152        if (ret == -EEXIST)
153            goto second_insert;
154        goto out;
155    }
156
157    leaf = path->nodes[0];
158    btrfs_cpu_key_to_disk(&disk_key, location);
159    btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
160    btrfs_set_dir_type(leaf, dir_item, type);
161    btrfs_set_dir_data_len(leaf, dir_item, 0);
162    btrfs_set_dir_name_len(leaf, dir_item, name_len);
163    btrfs_set_dir_transid(leaf, dir_item, trans->transid);
164    name_ptr = (unsigned long)(dir_item + 1);
165
166    write_extent_buffer(leaf, name, name_ptr, name_len);
167    btrfs_mark_buffer_dirty(leaf);
168
169second_insert:
170    /* FIXME, use some real flag for selecting the extra index */
171    if (root == root->fs_info->tree_root) {
172        ret = 0;
173        goto out;
174    }
175    btrfs_release_path(root, path);
176
177    btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
178    key.offset = index;
179    dir_item = insert_with_overflow(trans, root, path, &key, data_size,
180                    name, name_len);
181    if (IS_ERR(dir_item)) {
182        ret2 = PTR_ERR(dir_item);
183        goto out;
184    }
185    leaf = path->nodes[0];
186    btrfs_cpu_key_to_disk(&disk_key, location);
187    btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
188    btrfs_set_dir_type(leaf, dir_item, type);
189    btrfs_set_dir_data_len(leaf, dir_item, 0);
190    btrfs_set_dir_name_len(leaf, dir_item, name_len);
191    btrfs_set_dir_transid(leaf, dir_item, trans->transid);
192    name_ptr = (unsigned long)(dir_item + 1);
193    write_extent_buffer(leaf, name, name_ptr, name_len);
194    btrfs_mark_buffer_dirty(leaf);
195out:
196    btrfs_free_path(path);
197    if (ret)
198        return ret;
199    if (ret2)
200        return ret2;
201    return 0;
202}
203
204/*
205 * lookup a directory item based on name. 'dir' is the objectid
206 * we're searching in, and 'mod' tells us if you plan on deleting the
207 * item (use mod < 0) or changing the options (use mod > 0)
208 */
209struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
210                         struct btrfs_root *root,
211                         struct btrfs_path *path, u64 dir,
212                         const char *name, int name_len,
213                         int mod)
214{
215    int ret;
216    struct btrfs_key key;
217    int ins_len = mod < 0 ? -1 : 0;
218    int cow = mod != 0;
219    struct btrfs_key found_key;
220    struct extent_buffer *leaf;
221
222    key.objectid = dir;
223    btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
224
225    key.offset = btrfs_name_hash(name, name_len);
226
227    ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
228    if (ret < 0)
229        return ERR_PTR(ret);
230    if (ret > 0) {
231        if (path->slots[0] == 0)
232            return NULL;
233        path->slots[0]--;
234    }
235
236    leaf = path->nodes[0];
237    btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
238
239    if (found_key.objectid != dir ||
240        btrfs_key_type(&found_key) != BTRFS_DIR_ITEM_KEY ||
241        found_key.offset != key.offset)
242        return NULL;
243
244    return btrfs_match_dir_item_name(root, path, name, name_len);
245}
246
247/*
248 * lookup a directory item based on index. 'dir' is the objectid
249 * we're searching in, and 'mod' tells us if you plan on deleting the
250 * item (use mod < 0) or changing the options (use mod > 0)
251 *
252 * The name is used to make sure the index really points to the name you were
253 * looking for.
254 */
255struct btrfs_dir_item *
256btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
257                struct btrfs_root *root,
258                struct btrfs_path *path, u64 dir,
259                u64 objectid, const char *name, int name_len,
260                int mod)
261{
262    int ret;
263    struct btrfs_key key;
264    int ins_len = mod < 0 ? -1 : 0;
265    int cow = mod != 0;
266
267    key.objectid = dir;
268    btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
269    key.offset = objectid;
270
271    ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
272    if (ret < 0)
273        return ERR_PTR(ret);
274    if (ret > 0)
275        return ERR_PTR(-ENOENT);
276    return btrfs_match_dir_item_name(root, path, name, name_len);
277}
278
279struct btrfs_dir_item *
280btrfs_search_dir_index_item(struct btrfs_root *root,
281                struct btrfs_path *path, u64 dirid,
282                const char *name, int name_len)
283{
284    struct extent_buffer *leaf;
285    struct btrfs_dir_item *di;
286    struct btrfs_key key;
287    u32 nritems;
288    int ret;
289
290    key.objectid = dirid;
291    key.type = BTRFS_DIR_INDEX_KEY;
292    key.offset = 0;
293
294    ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
295    if (ret < 0)
296        return ERR_PTR(ret);
297
298    leaf = path->nodes[0];
299    nritems = btrfs_header_nritems(leaf);
300
301    while (1) {
302        if (path->slots[0] >= nritems) {
303            ret = btrfs_next_leaf(root, path);
304            if (ret < 0)
305                return ERR_PTR(ret);
306            if (ret > 0)
307                break;
308            leaf = path->nodes[0];
309            nritems = btrfs_header_nritems(leaf);
310            continue;
311        }
312
313        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
314        if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
315            break;
316
317        di = btrfs_match_dir_item_name(root, path, name, name_len);
318        if (di)
319            return di;
320
321        path->slots[0]++;
322    }
323    return NULL;
324}
325
326struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
327                      struct btrfs_root *root,
328                      struct btrfs_path *path, u64 dir,
329                      const char *name, u16 name_len,
330                      int mod)
331{
332    int ret;
333    struct btrfs_key key;
334    int ins_len = mod < 0 ? -1 : 0;
335    int cow = mod != 0;
336    struct btrfs_key found_key;
337    struct extent_buffer *leaf;
338
339    key.objectid = dir;
340    btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
341    key.offset = btrfs_name_hash(name, name_len);
342    ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
343    if (ret < 0)
344        return ERR_PTR(ret);
345    if (ret > 0) {
346        if (path->slots[0] == 0)
347            return NULL;
348        path->slots[0]--;
349    }
350
351    leaf = path->nodes[0];
352    btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
353
354    if (found_key.objectid != dir ||
355        btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY ||
356        found_key.offset != key.offset)
357        return NULL;
358
359    return btrfs_match_dir_item_name(root, path, name, name_len);
360}
361
362/*
363 * helper function to look at the directory item pointed to by 'path'
364 * this walks through all the entries in a dir item and finds one
365 * for a specific name.
366 */
367struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
368                  struct btrfs_path *path,
369                  const char *name, int name_len)
370{
371    struct btrfs_dir_item *dir_item;
372    unsigned long name_ptr;
373    u32 total_len;
374    u32 cur = 0;
375    u32 this_len;
376    struct extent_buffer *leaf;
377
378    leaf = path->nodes[0];
379    dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
380    total_len = btrfs_item_size_nr(leaf, path->slots[0]);
381    while (cur < total_len) {
382        this_len = sizeof(*dir_item) +
383            btrfs_dir_name_len(leaf, dir_item) +
384            btrfs_dir_data_len(leaf, dir_item);
385        name_ptr = (unsigned long)(dir_item + 1);
386
387        if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
388            memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
389            return dir_item;
390
391        cur += this_len;
392        dir_item = (struct btrfs_dir_item *)((char *)dir_item +
393                             this_len);
394    }
395    return NULL;
396}
397
398/*
399 * given a pointer into a directory item, delete it. This
400 * handles items that have more than one entry in them.
401 */
402int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
403                  struct btrfs_root *root,
404                  struct btrfs_path *path,
405                  struct btrfs_dir_item *di)
406{
407
408    struct extent_buffer *leaf;
409    u32 sub_item_len;
410    u32 item_len;
411    int ret = 0;
412
413    leaf = path->nodes[0];
414    sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
415        btrfs_dir_data_len(leaf, di);
416    item_len = btrfs_item_size_nr(leaf, path->slots[0]);
417    if (sub_item_len == item_len) {
418        ret = btrfs_del_item(trans, root, path);
419    } else {
420        /* MARKER */
421        unsigned long ptr = (unsigned long)di;
422        unsigned long start;
423
424        start = btrfs_item_ptr_offset(leaf, path->slots[0]);
425        memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
426            item_len - (ptr + sub_item_len - start));
427        ret = btrfs_truncate_item(trans, root, path,
428                      item_len - sub_item_len, 1);
429    }
430    return 0;
431}
432

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