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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/befs/btree.c
3 *
4 * Copyright (C) 2001-2002 Will Dyson <will_dyson@pobox.com>
5 *
6 * Licensed under the GNU GPL. See the file COPYING for details.
7 *
Lucas De Marchi25985ed2011-03-30 22:57:33 -03008 * 2002-02-05: Sergey S. Kostyliov added binary search within
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 * btree nodes.
10 *
11 * Many thanks to:
12 *
13 * Dominic Giampaolo, author of "Practical File System
14 * Design with the Be File System", for such a helpful book.
15 *
16 * Marcus J. Ranum, author of the b+tree package in
17 * comp.sources.misc volume 10. This code is not copied from that
18 * work, but it is partially based on it.
19 *
20 * Makoto Kato, author of the original BeFS for linux filesystem
21 * driver.
22 */
23
24#include <linux/kernel.h>
25#include <linux/string.h>
26#include <linux/slab.h>
27#include <linux/mm.h>
28#include <linux/buffer_head.h>
29
30#include "befs.h"
31#include "btree.h"
32#include "datastream.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34/*
35 * The btree functions in this file are built on top of the
36 * datastream.c interface, which is in turn built on top of the
37 * io.c interface.
38 */
39
40/* Befs B+tree structure:
41 *
42 * The first thing in the tree is the tree superblock. It tells you
43 * all kinds of useful things about the tree, like where the rootnode
44 * is located, and the size of the nodes (always 1024 with current version
45 * of BeOS).
46 *
47 * The rest of the tree consists of a series of nodes. Nodes contain a header
48 * (struct befs_btree_nodehead), the packed key data, an array of shorts
49 * containing the ending offsets for each of the keys, and an array of
50 * befs_off_t values. In interior nodes, the keys are the ending keys for
51 * the childnode they point to, and the values are offsets into the
52 * datastream containing the tree.
53 */
54
55/* Note:
56 *
57 * The book states 2 confusing things about befs b+trees. First,
58 * it states that the overflow field of node headers is used by internal nodes
59 * to point to another node that "effectively continues this one". Here is what
60 * I believe that means. Each key in internal nodes points to another node that
61 * contains key values less than itself. Inspection reveals that the last key
62 * in the internal node is not the last key in the index. Keys that are
63 * greater than the last key in the internal node go into the overflow node.
64 * I imagine there is a performance reason for this.
65 *
66 * Second, it states that the header of a btree node is sufficient to
67 * distinguish internal nodes from leaf nodes. Without saying exactly how.
68 * After figuring out the first, it becomes obvious that internal nodes have
69 * overflow nodes and leafnodes do not.
70 */
71
72/*
73 * Currently, this code is only good for directory B+trees.
74 * In order to be used for other BFS indexes, it needs to be extended to handle
75 * duplicate keys and non-string keytypes (int32, int64, float, double).
76 */
77
78/*
79 * In memory structure of each btree node
80 */
81typedef struct {
Al Viroa9721f32005-12-24 14:28:55 -050082 befs_host_btree_nodehead head; /* head of node converted to cpu byteorder */
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 struct buffer_head *bh;
84 befs_btree_nodehead *od_node; /* on disk node */
85} befs_btree_node;
86
87/* local constants */
88static const befs_off_t befs_bt_inval = 0xffffffffffffffffULL;
89
90/* local functions */
91static int befs_btree_seekleaf(struct super_block *sb, befs_data_stream * ds,
92 befs_btree_super * bt_super,
93 befs_btree_node * this_node,
94 befs_off_t * node_off);
95
96static int befs_bt_read_super(struct super_block *sb, befs_data_stream * ds,
97 befs_btree_super * sup);
98
99static int befs_bt_read_node(struct super_block *sb, befs_data_stream * ds,
100 befs_btree_node * node, befs_off_t node_off);
101
102static int befs_leafnode(befs_btree_node * node);
103
Al Viroa9721f32005-12-24 14:28:55 -0500104static fs16 *befs_bt_keylen_index(befs_btree_node * node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Al Viroa9721f32005-12-24 14:28:55 -0500106static fs64 *befs_bt_valarray(befs_btree_node * node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107
108static char *befs_bt_keydata(befs_btree_node * node);
109
110static int befs_find_key(struct super_block *sb, befs_btree_node * node,
111 const char *findkey, befs_off_t * value);
112
113static char *befs_bt_get_key(struct super_block *sb, befs_btree_node * node,
114 int index, u16 * keylen);
115
116static int befs_compare_strings(const void *key1, int keylen1,
117 const void *key2, int keylen2);
118
119/**
120 * befs_bt_read_super - read in btree superblock convert to cpu byteorder
121 * @sb: Filesystem superblock
122 * @ds: Datastream to read from
123 * @sup: Buffer in which to place the btree superblock
124 *
125 * Calls befs_read_datastream to read in the btree superblock and
126 * makes sure it is in cpu byteorder, byteswapping if necessary.
127 *
128 * On success, returns BEFS_OK and *@sup contains the btree superblock,
129 * in cpu byte order.
130 *
131 * On failure, BEFS_ERR is returned.
132 */
133static int
134befs_bt_read_super(struct super_block *sb, befs_data_stream * ds,
135 befs_btree_super * sup)
136{
137 struct buffer_head *bh = NULL;
Al Viroa9721f32005-12-24 14:28:55 -0500138 befs_disk_btree_super *od_sup = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700140 befs_debug(sb, "---> %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
142 bh = befs_read_datastream(sb, ds, 0, NULL);
143
144 if (!bh) {
145 befs_error(sb, "Couldn't read index header.");
146 goto error;
147 }
Al Viroa9721f32005-12-24 14:28:55 -0500148 od_sup = (befs_disk_btree_super *) bh->b_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 befs_dump_index_entry(sb, od_sup);
150
151 sup->magic = fs32_to_cpu(sb, od_sup->magic);
152 sup->node_size = fs32_to_cpu(sb, od_sup->node_size);
153 sup->max_depth = fs32_to_cpu(sb, od_sup->max_depth);
154 sup->data_type = fs32_to_cpu(sb, od_sup->data_type);
155 sup->root_node_ptr = fs64_to_cpu(sb, od_sup->root_node_ptr);
156 sup->free_node_ptr = fs64_to_cpu(sb, od_sup->free_node_ptr);
157 sup->max_size = fs64_to_cpu(sb, od_sup->max_size);
158
159 brelse(bh);
160 if (sup->magic != BEFS_BTREE_MAGIC) {
161 befs_error(sb, "Index header has bad magic.");
162 goto error;
163 }
164
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700165 befs_debug(sb, "<--- %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 return BEFS_OK;
167
168 error:
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700169 befs_debug(sb, "<--- %s ERROR", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 return BEFS_ERR;
171}
172
173/**
174 * befs_bt_read_node - read in btree node and convert to cpu byteorder
175 * @sb: Filesystem superblock
176 * @ds: Datastream to read from
177 * @node: Buffer in which to place the btree node
178 * @node_off: Starting offset (in bytes) of the node in @ds
179 *
180 * Calls befs_read_datastream to read in the indicated btree node and
181 * makes sure its header fields are in cpu byteorder, byteswapping if
182 * necessary.
183 * Note: node->bh must be NULL when this function called first
184 * time. Don't forget brelse(node->bh) after last call.
185 *
186 * On success, returns BEFS_OK and *@node contains the btree node that
187 * starts at @node_off, with the node->head fields in cpu byte order.
188 *
189 * On failure, BEFS_ERR is returned.
190 */
191
192static int
193befs_bt_read_node(struct super_block *sb, befs_data_stream * ds,
194 befs_btree_node * node, befs_off_t node_off)
195{
196 uint off = 0;
197
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700198 befs_debug(sb, "---> %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
200 if (node->bh)
201 brelse(node->bh);
202
203 node->bh = befs_read_datastream(sb, ds, node_off, &off);
204 if (!node->bh) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700205 befs_error(sb, "%s failed to read "
206 "node at %llu", __func__, node_off);
207 befs_debug(sb, "<--- %s ERROR", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208
209 return BEFS_ERR;
210 }
211 node->od_node =
212 (befs_btree_nodehead *) ((void *) node->bh->b_data + off);
213
214 befs_dump_index_node(sb, node->od_node);
215
216 node->head.left = fs64_to_cpu(sb, node->od_node->left);
217 node->head.right = fs64_to_cpu(sb, node->od_node->right);
218 node->head.overflow = fs64_to_cpu(sb, node->od_node->overflow);
219 node->head.all_key_count =
220 fs16_to_cpu(sb, node->od_node->all_key_count);
221 node->head.all_key_length =
222 fs16_to_cpu(sb, node->od_node->all_key_length);
223
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700224 befs_debug(sb, "<--- %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 return BEFS_OK;
226}
227
228/**
229 * befs_btree_find - Find a key in a befs B+tree
230 * @sb: Filesystem superblock
231 * @ds: Datastream containing btree
232 * @key: Key string to lookup in btree
233 * @value: Value stored with @key
234 *
Joe Perchesc78bad12008-02-03 17:33:42 +0200235 * On success, returns BEFS_OK and sets *@value to the value stored
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 * with @key (usually the disk block number of an inode).
237 *
238 * On failure, returns BEFS_ERR or BEFS_BT_NOT_FOUND.
239 *
240 * Algorithm:
241 * Read the superblock and rootnode of the b+tree.
242 * Drill down through the interior nodes using befs_find_key().
243 * Once at the correct leaf node, use befs_find_key() again to get the
244 * actuall value stored with the key.
245 */
246int
247befs_btree_find(struct super_block *sb, befs_data_stream * ds,
248 const char *key, befs_off_t * value)
249{
250 befs_btree_node *this_node = NULL;
251 befs_btree_super bt_super;
252 befs_off_t node_off;
253 int res;
254
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700255 befs_debug(sb, "---> %s Key: %s", __func__, key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
257 if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) {
258 befs_error(sb,
259 "befs_btree_find() failed to read index superblock");
260 goto error;
261 }
262
Robert P. J. Day5cbded52006-12-13 00:35:56 -0800263 this_node = kmalloc(sizeof (befs_btree_node),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 GFP_NOFS);
265 if (!this_node) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700266 befs_error(sb, "befs_btree_find() failed to allocate %zu "
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 "bytes of memory", sizeof (befs_btree_node));
268 goto error;
269 }
270
271 this_node->bh = NULL;
272
273 /* read in root node */
274 node_off = bt_super.root_node_ptr;
275 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
276 befs_error(sb, "befs_btree_find() failed to read "
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700277 "node at %llu", node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 goto error_alloc;
279 }
280
281 while (!befs_leafnode(this_node)) {
282 res = befs_find_key(sb, this_node, key, &node_off);
283 if (res == BEFS_BT_NOT_FOUND)
284 node_off = this_node->head.overflow;
285 /* if no match, go to overflow node */
286 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
287 befs_error(sb, "befs_btree_find() failed to read "
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700288 "node at %llu", node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 goto error_alloc;
290 }
291 }
292
293 /* at the correct leaf node now */
294
295 res = befs_find_key(sb, this_node, key, value);
296
297 brelse(this_node->bh);
298 kfree(this_node);
299
300 if (res != BEFS_BT_MATCH) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700301 befs_debug(sb, "<--- %s Key %s not found", __func__, key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 *value = 0;
303 return BEFS_BT_NOT_FOUND;
304 }
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700305 befs_debug(sb, "<--- %s Found key %s, value %llu", __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 key, *value);
307 return BEFS_OK;
308
309 error_alloc:
310 kfree(this_node);
311 error:
312 *value = 0;
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700313 befs_debug(sb, "<--- %s ERROR", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 return BEFS_ERR;
315}
316
317/**
318 * befs_find_key - Search for a key within a node
319 * @sb: Filesystem superblock
320 * @node: Node to find the key within
Fabian Frederick817e1d92014-06-06 14:36:17 -0700321 * @findkey: Keystring to search for
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 * @value: If key is found, the value stored with the key is put here
323 *
324 * finds exact match if one exists, and returns BEFS_BT_MATCH
325 * If no exact match, finds first key in node that is greater
326 * (alphabetically) than the search key and returns BEFS_BT_PARMATCH
327 * (for partial match, I guess). Can you think of something better to
328 * call it?
329 *
330 * If no key was a match or greater than the search key, return
331 * BEFS_BT_NOT_FOUND.
332 *
333 * Use binary search instead of a linear.
334 */
335static int
336befs_find_key(struct super_block *sb, befs_btree_node * node,
337 const char *findkey, befs_off_t * value)
338{
339 int first, last, mid;
340 int eq;
341 u16 keylen;
342 int findkey_len;
343 char *thiskey;
Al Viroa9721f32005-12-24 14:28:55 -0500344 fs64 *valarray;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700346 befs_debug(sb, "---> %s %s", __func__, findkey);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
348 *value = 0;
349
350 findkey_len = strlen(findkey);
351
352 /* if node can not contain key, just skeep this node */
353 last = node->head.all_key_count - 1;
354 thiskey = befs_bt_get_key(sb, node, last, &keylen);
355
356 eq = befs_compare_strings(thiskey, keylen, findkey, findkey_len);
357 if (eq < 0) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700358 befs_debug(sb, "<--- %s %s not found", __func__, findkey);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 return BEFS_BT_NOT_FOUND;
360 }
361
362 valarray = befs_bt_valarray(node);
363
364 /* simple binary search */
365 first = 0;
366 mid = 0;
367 while (last >= first) {
368 mid = (last + first) / 2;
369 befs_debug(sb, "first: %d, last: %d, mid: %d", first, last,
370 mid);
371 thiskey = befs_bt_get_key(sb, node, mid, &keylen);
372 eq = befs_compare_strings(thiskey, keylen, findkey,
373 findkey_len);
374
375 if (eq == 0) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700376 befs_debug(sb, "<--- %s found %s at %d",
377 __func__, thiskey, mid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378
379 *value = fs64_to_cpu(sb, valarray[mid]);
380 return BEFS_BT_MATCH;
381 }
382 if (eq > 0)
383 last = mid - 1;
384 else
385 first = mid + 1;
386 }
387 if (eq < 0)
388 *value = fs64_to_cpu(sb, valarray[mid + 1]);
389 else
390 *value = fs64_to_cpu(sb, valarray[mid]);
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700391 befs_debug(sb, "<--- %s found %s at %d", __func__, thiskey, mid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 return BEFS_BT_PARMATCH;
393}
394
395/**
396 * befs_btree_read - Traverse leafnodes of a btree
397 * @sb: Filesystem superblock
398 * @ds: Datastream containing btree
399 * @key_no: Key number (alphabetical order) of key to read
400 * @bufsize: Size of the buffer to return key in
401 * @keybuf: Pointer to a buffer to put the key in
402 * @keysize: Length of the returned key
403 * @value: Value stored with the returned key
404 *
405 * Heres how it works: Key_no is the index of the key/value pair to
406 * return in keybuf/value.
407 * Bufsize is the size of keybuf (BEFS_NAME_LEN+1 is a good size). Keysize is
Fabian Frederick6cb103b2014-06-06 14:36:15 -0700408 * the number of characters in the key (just a convenience).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 *
410 * Algorithm:
411 * Get the first leafnode of the tree. See if the requested key is in that
412 * node. If not, follow the node->right link to the next leafnode. Repeat
413 * until the (key_no)th key is found or the tree is out of keys.
414 */
415int
416befs_btree_read(struct super_block *sb, befs_data_stream * ds,
417 loff_t key_no, size_t bufsize, char *keybuf, size_t * keysize,
418 befs_off_t * value)
419{
420 befs_btree_node *this_node;
421 befs_btree_super bt_super;
422 befs_off_t node_off = 0;
423 int cur_key;
Al Viroa9721f32005-12-24 14:28:55 -0500424 fs64 *valarray;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 char *keystart;
426 u16 keylen;
427 int res;
428
429 uint key_sum = 0;
430
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700431 befs_debug(sb, "---> %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432
433 if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) {
434 befs_error(sb,
435 "befs_btree_read() failed to read index superblock");
436 goto error;
437 }
438
Zhang Yanfeiee68a3c2013-03-12 13:35:09 +0800439 if ((this_node = kmalloc(sizeof (befs_btree_node), GFP_NOFS)) == NULL) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700440 befs_error(sb, "befs_btree_read() failed to allocate %zu "
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 "bytes of memory", sizeof (befs_btree_node));
442 goto error;
443 }
444
445 node_off = bt_super.root_node_ptr;
446 this_node->bh = NULL;
447
448 /* seeks down to first leafnode, reads it into this_node */
449 res = befs_btree_seekleaf(sb, ds, &bt_super, this_node, &node_off);
450 if (res == BEFS_BT_EMPTY) {
451 brelse(this_node->bh);
452 kfree(this_node);
453 *value = 0;
454 *keysize = 0;
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700455 befs_debug(sb, "<--- %s Tree is EMPTY", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 return BEFS_BT_EMPTY;
457 } else if (res == BEFS_ERR) {
458 goto error_alloc;
459 }
460
461 /* find the leaf node containing the key_no key */
462
463 while (key_sum + this_node->head.all_key_count <= key_no) {
464
465 /* no more nodes to look in: key_no is too large */
466 if (this_node->head.right == befs_bt_inval) {
467 *keysize = 0;
468 *value = 0;
469 befs_debug(sb,
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700470 "<--- %s END of keys at %llu", __func__,
471 (unsigned long long)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 key_sum + this_node->head.all_key_count);
473 brelse(this_node->bh);
474 kfree(this_node);
475 return BEFS_BT_END;
476 }
477
478 key_sum += this_node->head.all_key_count;
479 node_off = this_node->head.right;
480
481 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700482 befs_error(sb, "%s failed to read node at %llu",
483 __func__, (unsigned long long)node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 goto error_alloc;
485 }
486 }
487
488 /* how many keys into this_node is key_no */
489 cur_key = key_no - key_sum;
490
491 /* get pointers to datastructures within the node body */
492 valarray = befs_bt_valarray(this_node);
493
494 keystart = befs_bt_get_key(sb, this_node, cur_key, &keylen);
495
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700496 befs_debug(sb, "Read [%llu,%d]: keysize %d",
497 (long long unsigned int)node_off, (int)cur_key,
498 (int)keylen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499
500 if (bufsize < keylen + 1) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700501 befs_error(sb, "%s keybuf too small (%zu) "
502 "for key of size %d", __func__, bufsize, keylen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 brelse(this_node->bh);
504 goto error_alloc;
Fabian Frederick6cb103b2014-06-06 14:36:15 -0700505 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
Fabian Frederick6cb103b2014-06-06 14:36:15 -0700507 strlcpy(keybuf, keystart, keylen + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 *value = fs64_to_cpu(sb, valarray[cur_key]);
509 *keysize = keylen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700511 befs_debug(sb, "Read [%llu,%d]: Key \"%.*s\", Value %llu", node_off,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 cur_key, keylen, keybuf, *value);
513
514 brelse(this_node->bh);
515 kfree(this_node);
516
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700517 befs_debug(sb, "<--- %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518
519 return BEFS_OK;
520
521 error_alloc:
522 kfree(this_node);
523
524 error:
525 *keysize = 0;
526 *value = 0;
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700527 befs_debug(sb, "<--- %s ERROR", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 return BEFS_ERR;
529}
530
531/**
532 * befs_btree_seekleaf - Find the first leafnode in the btree
533 * @sb: Filesystem superblock
534 * @ds: Datastream containing btree
535 * @bt_super: Pointer to the superblock of the btree
536 * @this_node: Buffer to return the leafnode in
537 * @node_off: Pointer to offset of current node within datastream. Modified
538 * by the function.
539 *
540 *
541 * Helper function for btree traverse. Moves the current position to the
542 * start of the first leaf node.
543 *
544 * Also checks for an empty tree. If there are no keys, returns BEFS_BT_EMPTY.
545 */
546static int
547befs_btree_seekleaf(struct super_block *sb, befs_data_stream * ds,
548 befs_btree_super * bt_super, befs_btree_node * this_node,
549 befs_off_t * node_off)
550{
551
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700552 befs_debug(sb, "---> %s", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
554 if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700555 befs_error(sb, "%s failed to read "
556 "node at %llu", __func__, *node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 goto error;
558 }
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700559 befs_debug(sb, "Seekleaf to root node %llu", *node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560
561 if (this_node->head.all_key_count == 0 && befs_leafnode(this_node)) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700562 befs_debug(sb, "<--- %s Tree is EMPTY", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 return BEFS_BT_EMPTY;
564 }
565
566 while (!befs_leafnode(this_node)) {
567
568 if (this_node->head.all_key_count == 0) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700569 befs_debug(sb, "%s encountered "
570 "an empty interior node: %llu. Using Overflow "
571 "node: %llu", __func__, *node_off,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 this_node->head.overflow);
573 *node_off = this_node->head.overflow;
574 } else {
Al Viroa9721f32005-12-24 14:28:55 -0500575 fs64 *valarray = befs_bt_valarray(this_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 *node_off = fs64_to_cpu(sb, valarray[0]);
577 }
578 if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) {
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700579 befs_error(sb, "%s failed to read "
580 "node at %llu", __func__, *node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 goto error;
582 }
583
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700584 befs_debug(sb, "Seekleaf to child node %llu", *node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 }
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700586 befs_debug(sb, "Node %llu is a leaf node", *node_off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587
588 return BEFS_OK;
589
590 error:
Fabian Frederickdac52fc2014-04-03 14:50:23 -0700591 befs_debug(sb, "<--- %s ERROR", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 return BEFS_ERR;
593}
594
595/**
596 * befs_leafnode - Determine if the btree node is a leaf node or an
597 * interior node
598 * @node: Pointer to node structure to test
599 *
600 * Return 1 if leaf, 0 if interior
601 */
602static int
603befs_leafnode(befs_btree_node * node)
604{
605 /* all interior nodes (and only interior nodes) have an overflow node */
606 if (node->head.overflow == befs_bt_inval)
607 return 1;
608 else
609 return 0;
610}
611
612/**
613 * befs_bt_keylen_index - Finds start of keylen index in a node
614 * @node: Pointer to the node structure to find the keylen index within
615 *
616 * Returns a pointer to the start of the key length index array
617 * of the B+tree node *@node
618 *
619 * "The length of all the keys in the node is added to the size of the
620 * header and then rounded up to a multiple of four to get the beginning
621 * of the key length index" (p.88, practical filesystem design).
622 *
623 * Except that rounding up to 8 works, and rounding up to 4 doesn't.
624 */
Al Viroa9721f32005-12-24 14:28:55 -0500625static fs16 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626befs_bt_keylen_index(befs_btree_node * node)
627{
628 const int keylen_align = 8;
629 unsigned long int off =
630 (sizeof (befs_btree_nodehead) + node->head.all_key_length);
631 ulong tmp = off % keylen_align;
632
633 if (tmp)
634 off += keylen_align - tmp;
635
Al Viroa9721f32005-12-24 14:28:55 -0500636 return (fs16 *) ((void *) node->od_node + off);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637}
638
639/**
640 * befs_bt_valarray - Finds the start of value array in a node
641 * @node: Pointer to the node structure to find the value array within
642 *
643 * Returns a pointer to the start of the value array
644 * of the node pointed to by the node header
645 */
Al Viroa9721f32005-12-24 14:28:55 -0500646static fs64 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647befs_bt_valarray(befs_btree_node * node)
648{
649 void *keylen_index_start = (void *) befs_bt_keylen_index(node);
Al Viroa9721f32005-12-24 14:28:55 -0500650 size_t keylen_index_size = node->head.all_key_count * sizeof (fs16);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651
Al Viroa9721f32005-12-24 14:28:55 -0500652 return (fs64 *) (keylen_index_start + keylen_index_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653}
654
655/**
656 * befs_bt_keydata - Finds start of keydata array in a node
657 * @node: Pointer to the node structure to find the keydata array within
658 *
659 * Returns a pointer to the start of the keydata array
660 * of the node pointed to by the node header
661 */
662static char *
663befs_bt_keydata(befs_btree_node * node)
664{
665 return (char *) ((void *) node->od_node + sizeof (befs_btree_nodehead));
666}
667
668/**
669 * befs_bt_get_key - returns a pointer to the start of a key
670 * @sb: filesystem superblock
671 * @node: node in which to look for the key
672 * @index: the index of the key to get
673 * @keylen: modified to be the length of the key at @index
674 *
675 * Returns a valid pointer into @node on success.
676 * Returns NULL on failure (bad input) and sets *@keylen = 0
677 */
678static char *
679befs_bt_get_key(struct super_block *sb, befs_btree_node * node,
680 int index, u16 * keylen)
681{
682 int prev_key_end;
683 char *keystart;
Al Viroa9721f32005-12-24 14:28:55 -0500684 fs16 *keylen_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685
686 if (index < 0 || index > node->head.all_key_count) {
687 *keylen = 0;
688 return NULL;
689 }
690
691 keystart = befs_bt_keydata(node);
692 keylen_index = befs_bt_keylen_index(node);
693
694 if (index == 0)
695 prev_key_end = 0;
696 else
697 prev_key_end = fs16_to_cpu(sb, keylen_index[index - 1]);
698
699 *keylen = fs16_to_cpu(sb, keylen_index[index]) - prev_key_end;
700
701 return keystart + prev_key_end;
702}
703
704/**
705 * befs_compare_strings - compare two strings
706 * @key1: pointer to the first key to be compared
707 * @keylen1: length in bytes of key1
708 * @key2: pointer to the second key to be compared
Fabian Frederick817e1d92014-06-06 14:36:17 -0700709 * @keylen2: length in bytes of key2
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 *
711 * Returns 0 if @key1 and @key2 are equal.
712 * Returns >0 if @key1 is greater.
713 * Returns <0 if @key2 is greater..
714 */
715static int
716befs_compare_strings(const void *key1, int keylen1,
717 const void *key2, int keylen2)
718{
719 int len = min_t(int, keylen1, keylen2);
720 int result = strncmp(key1, key2, len);
721 if (result == 0)
722 result = keylen1 - keylen2;
723 return result;
724}
725
726/* These will be used for non-string keyed btrees */
727#if 0
728static int
729btree_compare_int32(cont void *key1, int keylen1, const void *key2, int keylen2)
730{
731 return *(int32_t *) key1 - *(int32_t *) key2;
732}
733
734static int
735btree_compare_uint32(cont void *key1, int keylen1,
736 const void *key2, int keylen2)
737{
738 if (*(u_int32_t *) key1 == *(u_int32_t *) key2)
739 return 0;
740 else if (*(u_int32_t *) key1 > *(u_int32_t *) key2)
741 return 1;
742
743 return -1;
744}
745static int
746btree_compare_int64(cont void *key1, int keylen1, const void *key2, int keylen2)
747{
748 if (*(int64_t *) key1 == *(int64_t *) key2)
749 return 0;
750 else if (*(int64_t *) key1 > *(int64_t *) key2)
751 return 1;
752
753 return -1;
754}
755
756static int
757btree_compare_uint64(cont void *key1, int keylen1,
758 const void *key2, int keylen2)
759{
760 if (*(u_int64_t *) key1 == *(u_int64_t *) key2)
761 return 0;
762 else if (*(u_int64_t *) key1 > *(u_int64_t *) key2)
763 return 1;
764
765 return -1;
766}
767
768static int
769btree_compare_float(cont void *key1, int keylen1, const void *key2, int keylen2)
770{
771 float result = *(float *) key1 - *(float *) key2;
772 if (result == 0.0f)
773 return 0;
774
775 return (result < 0.0f) ? -1 : 1;
776}
777
778static int
779btree_compare_double(cont void *key1, int keylen1,
780 const void *key2, int keylen2)
781{
782 double result = *(double *) key1 - *(double *) key2;
783 if (result == 0.0)
784 return 0;
785
786 return (result < 0.0) ? -1 : 1;
787}
788#endif //0