xref: /linux/fs/hfs/bnode.c (revision d6fd48ef) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/hfs/bnode.c
4  *
5  * Copyright (C) 2001
6  * Brad Boyer (flar@allandria.com)
7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
8  *
9  * Handle basic btree node operations
10  */
11 
12 #include <linux/pagemap.h>
13 #include <linux/slab.h>
14 #include <linux/swap.h>
15 
16 #include "btree.h"
17 
18 void hfs_bnode_read(struct hfs_bnode *node, void *buf, int off, int len)
19 {
20 	struct page *page;
21 	int pagenum;
22 	int bytes_read;
23 	int bytes_to_read;
24 
25 	off += node->page_offset;
26 	pagenum = off >> PAGE_SHIFT;
27 	off &= ~PAGE_MASK; /* compute page offset for the first page */
28 
29 	for (bytes_read = 0; bytes_read < len; bytes_read += bytes_to_read) {
30 		if (pagenum >= node->tree->pages_per_bnode)
31 			break;
32 		page = node->page[pagenum];
33 		bytes_to_read = min_t(int, len - bytes_read, PAGE_SIZE - off);
34 
35 		memcpy_from_page(buf + bytes_read, page, off, bytes_to_read);
36 
37 		pagenum++;
38 		off = 0; /* page offset only applies to the first page */
39 	}
40 }
41 
42 u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)
43 {
44 	__be16 data;
45 	// optimize later...
46 	hfs_bnode_read(node, &data, off, 2);
47 	return be16_to_cpu(data);
48 }
49 
50 u8 hfs_bnode_read_u8(struct hfs_bnode *node, int off)
51 {
52 	u8 data;
53 	// optimize later...
54 	hfs_bnode_read(node, &data, off, 1);
55 	return data;
56 }
57 
58 void hfs_bnode_read_key(struct hfs_bnode *node, void *key, int off)
59 {
60 	struct hfs_btree *tree;
61 	int key_len;
62 
63 	tree = node->tree;
64 	if (node->type == HFS_NODE_LEAF ||
65 	    tree->attributes & HFS_TREE_VARIDXKEYS)
66 		key_len = hfs_bnode_read_u8(node, off) + 1;
67 	else
68 		key_len = tree->max_key_len + 1;
69 
70 	hfs_bnode_read(node, key, off, key_len);
71 }
72 
73 void hfs_bnode_write(struct hfs_bnode *node, void *buf, int off, int len)
74 {
75 	struct page *page;
76 
77 	off += node->page_offset;
78 	page = node->page[0];
79 
80 	memcpy_to_page(page, off, buf, len);
81 	set_page_dirty(page);
82 }
83 
84 void hfs_bnode_write_u16(struct hfs_bnode *node, int off, u16 data)
85 {
86 	__be16 v = cpu_to_be16(data);
87 	// optimize later...
88 	hfs_bnode_write(node, &v, off, 2);
89 }
90 
91 void hfs_bnode_write_u8(struct hfs_bnode *node, int off, u8 data)
92 {
93 	// optimize later...
94 	hfs_bnode_write(node, &data, off, 1);
95 }
96 
97 void hfs_bnode_clear(struct hfs_bnode *node, int off, int len)
98 {
99 	struct page *page;
100 
101 	off += node->page_offset;
102 	page = node->page[0];
103 
104 	memzero_page(page, off, len);
105 	set_page_dirty(page);
106 }
107 
108 void hfs_bnode_copy(struct hfs_bnode *dst_node, int dst,
109 		struct hfs_bnode *src_node, int src, int len)
110 {
111 	struct page *src_page, *dst_page;
112 
113 	hfs_dbg(BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
114 	if (!len)
115 		return;
116 	src += src_node->page_offset;
117 	dst += dst_node->page_offset;
118 	src_page = src_node->page[0];
119 	dst_page = dst_node->page[0];
120 
121 	memcpy_page(dst_page, dst, src_page, src, len);
122 	set_page_dirty(dst_page);
123 }
124 
125 void hfs_bnode_move(struct hfs_bnode *node, int dst, int src, int len)
126 {
127 	struct page *page;
128 	void *ptr;
129 
130 	hfs_dbg(BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
131 	if (!len)
132 		return;
133 	src += node->page_offset;
134 	dst += node->page_offset;
135 	page = node->page[0];
136 	ptr = kmap_local_page(page);
137 	memmove(ptr + dst, ptr + src, len);
138 	kunmap_local(ptr);
139 	set_page_dirty(page);
140 }
141 
142 void hfs_bnode_dump(struct hfs_bnode *node)
143 {
144 	struct hfs_bnode_desc desc;
145 	__be32 cnid;
146 	int i, off, key_off;
147 
148 	hfs_dbg(BNODE_MOD, "bnode: %d\n", node->this);
149 	hfs_bnode_read(node, &desc, 0, sizeof(desc));
150 	hfs_dbg(BNODE_MOD, "%d, %d, %d, %d, %d\n",
151 		be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
152 		desc.type, desc.height, be16_to_cpu(desc.num_recs));
153 
154 	off = node->tree->node_size - 2;
155 	for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
156 		key_off = hfs_bnode_read_u16(node, off);
157 		hfs_dbg_cont(BNODE_MOD, " %d", key_off);
158 		if (i && node->type == HFS_NODE_INDEX) {
159 			int tmp;
160 
161 			if (node->tree->attributes & HFS_TREE_VARIDXKEYS)
162 				tmp = (hfs_bnode_read_u8(node, key_off) | 1) + 1;
163 			else
164 				tmp = node->tree->max_key_len + 1;
165 			hfs_dbg_cont(BNODE_MOD, " (%d,%d",
166 				     tmp, hfs_bnode_read_u8(node, key_off));
167 			hfs_bnode_read(node, &cnid, key_off + tmp, 4);
168 			hfs_dbg_cont(BNODE_MOD, ",%d)", be32_to_cpu(cnid));
169 		} else if (i && node->type == HFS_NODE_LEAF) {
170 			int tmp;
171 
172 			tmp = hfs_bnode_read_u8(node, key_off);
173 			hfs_dbg_cont(BNODE_MOD, " (%d)", tmp);
174 		}
175 	}
176 	hfs_dbg_cont(BNODE_MOD, "\n");
177 }
178 
179 void hfs_bnode_unlink(struct hfs_bnode *node)
180 {
181 	struct hfs_btree *tree;
182 	struct hfs_bnode *tmp;
183 	__be32 cnid;
184 
185 	tree = node->tree;
186 	if (node->prev) {
187 		tmp = hfs_bnode_find(tree, node->prev);
188 		if (IS_ERR(tmp))
189 			return;
190 		tmp->next = node->next;
191 		cnid = cpu_to_be32(tmp->next);
192 		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
193 		hfs_bnode_put(tmp);
194 	} else if (node->type == HFS_NODE_LEAF)
195 		tree->leaf_head = node->next;
196 
197 	if (node->next) {
198 		tmp = hfs_bnode_find(tree, node->next);
199 		if (IS_ERR(tmp))
200 			return;
201 		tmp->prev = node->prev;
202 		cnid = cpu_to_be32(tmp->prev);
203 		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
204 		hfs_bnode_put(tmp);
205 	} else if (node->type == HFS_NODE_LEAF)
206 		tree->leaf_tail = node->prev;
207 
208 	// move down?
209 	if (!node->prev && !node->next) {
210 		printk(KERN_DEBUG "hfs_btree_del_level\n");
211 	}
212 	if (!node->parent) {
213 		tree->root = 0;
214 		tree->depth = 0;
215 	}
216 	set_bit(HFS_BNODE_DELETED, &node->flags);
217 }
218 
219 static inline int hfs_bnode_hash(u32 num)
220 {
221 	num = (num >> 16) + num;
222 	num += num >> 8;
223 	return num & (NODE_HASH_SIZE - 1);
224 }
225 
226 struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
227 {
228 	struct hfs_bnode *node;
229 
230 	if (cnid >= tree->node_count) {
231 		pr_err("request for non-existent node %d in B*Tree\n", cnid);
232 		return NULL;
233 	}
234 
235 	for (node = tree->node_hash[hfs_bnode_hash(cnid)];
236 	     node; node = node->next_hash) {
237 		if (node->this == cnid) {
238 			return node;
239 		}
240 	}
241 	return NULL;
242 }
243 
244 static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
245 {
246 	struct hfs_bnode *node, *node2;
247 	struct address_space *mapping;
248 	struct page *page;
249 	int size, block, i, hash;
250 	loff_t off;
251 
252 	if (cnid >= tree->node_count) {
253 		pr_err("request for non-existent node %d in B*Tree\n", cnid);
254 		return NULL;
255 	}
256 
257 	size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
258 		sizeof(struct page *);
259 	node = kzalloc(size, GFP_KERNEL);
260 	if (!node)
261 		return NULL;
262 	node->tree = tree;
263 	node->this = cnid;
264 	set_bit(HFS_BNODE_NEW, &node->flags);
265 	atomic_set(&node->refcnt, 1);
266 	hfs_dbg(BNODE_REFS, "new_node(%d:%d): 1\n",
267 		node->tree->cnid, node->this);
268 	init_waitqueue_head(&node->lock_wq);
269 	spin_lock(&tree->hash_lock);
270 	node2 = hfs_bnode_findhash(tree, cnid);
271 	if (!node2) {
272 		hash = hfs_bnode_hash(cnid);
273 		node->next_hash = tree->node_hash[hash];
274 		tree->node_hash[hash] = node;
275 		tree->node_hash_cnt++;
276 	} else {
277 		hfs_bnode_get(node2);
278 		spin_unlock(&tree->hash_lock);
279 		kfree(node);
280 		wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
281 		return node2;
282 	}
283 	spin_unlock(&tree->hash_lock);
284 
285 	mapping = tree->inode->i_mapping;
286 	off = (loff_t)cnid * tree->node_size;
287 	block = off >> PAGE_SHIFT;
288 	node->page_offset = off & ~PAGE_MASK;
289 	for (i = 0; i < tree->pages_per_bnode; i++) {
290 		page = read_mapping_page(mapping, block++, NULL);
291 		if (IS_ERR(page))
292 			goto fail;
293 		node->page[i] = page;
294 	}
295 
296 	return node;
297 fail:
298 	set_bit(HFS_BNODE_ERROR, &node->flags);
299 	return node;
300 }
301 
302 void hfs_bnode_unhash(struct hfs_bnode *node)
303 {
304 	struct hfs_bnode **p;
305 
306 	hfs_dbg(BNODE_REFS, "remove_node(%d:%d): %d\n",
307 		node->tree->cnid, node->this, atomic_read(&node->refcnt));
308 	for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
309 	     *p && *p != node; p = &(*p)->next_hash)
310 		;
311 	BUG_ON(!*p);
312 	*p = node->next_hash;
313 	node->tree->node_hash_cnt--;
314 }
315 
316 /* Load a particular node out of a tree */
317 struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
318 {
319 	struct hfs_bnode *node;
320 	struct hfs_bnode_desc *desc;
321 	int i, rec_off, off, next_off;
322 	int entry_size, key_size;
323 
324 	spin_lock(&tree->hash_lock);
325 	node = hfs_bnode_findhash(tree, num);
326 	if (node) {
327 		hfs_bnode_get(node);
328 		spin_unlock(&tree->hash_lock);
329 		wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
330 		if (test_bit(HFS_BNODE_ERROR, &node->flags))
331 			goto node_error;
332 		return node;
333 	}
334 	spin_unlock(&tree->hash_lock);
335 	node = __hfs_bnode_create(tree, num);
336 	if (!node)
337 		return ERR_PTR(-ENOMEM);
338 	if (test_bit(HFS_BNODE_ERROR, &node->flags))
339 		goto node_error;
340 	if (!test_bit(HFS_BNODE_NEW, &node->flags))
341 		return node;
342 
343 	desc = (struct hfs_bnode_desc *)(kmap_local_page(node->page[0]) +
344 					 node->page_offset);
345 	node->prev = be32_to_cpu(desc->prev);
346 	node->next = be32_to_cpu(desc->next);
347 	node->num_recs = be16_to_cpu(desc->num_recs);
348 	node->type = desc->type;
349 	node->height = desc->height;
350 	kunmap_local(desc);
351 
352 	switch (node->type) {
353 	case HFS_NODE_HEADER:
354 	case HFS_NODE_MAP:
355 		if (node->height != 0)
356 			goto node_error;
357 		break;
358 	case HFS_NODE_LEAF:
359 		if (node->height != 1)
360 			goto node_error;
361 		break;
362 	case HFS_NODE_INDEX:
363 		if (node->height <= 1 || node->height > tree->depth)
364 			goto node_error;
365 		break;
366 	default:
367 		goto node_error;
368 	}
369 
370 	rec_off = tree->node_size - 2;
371 	off = hfs_bnode_read_u16(node, rec_off);
372 	if (off != sizeof(struct hfs_bnode_desc))
373 		goto node_error;
374 	for (i = 1; i <= node->num_recs; off = next_off, i++) {
375 		rec_off -= 2;
376 		next_off = hfs_bnode_read_u16(node, rec_off);
377 		if (next_off <= off ||
378 		    next_off > tree->node_size ||
379 		    next_off & 1)
380 			goto node_error;
381 		entry_size = next_off - off;
382 		if (node->type != HFS_NODE_INDEX &&
383 		    node->type != HFS_NODE_LEAF)
384 			continue;
385 		key_size = hfs_bnode_read_u8(node, off) + 1;
386 		if (key_size >= entry_size /*|| key_size & 1*/)
387 			goto node_error;
388 	}
389 	clear_bit(HFS_BNODE_NEW, &node->flags);
390 	wake_up(&node->lock_wq);
391 	return node;
392 
393 node_error:
394 	set_bit(HFS_BNODE_ERROR, &node->flags);
395 	clear_bit(HFS_BNODE_NEW, &node->flags);
396 	wake_up(&node->lock_wq);
397 	hfs_bnode_put(node);
398 	return ERR_PTR(-EIO);
399 }
400 
401 void hfs_bnode_free(struct hfs_bnode *node)
402 {
403 	int i;
404 
405 	for (i = 0; i < node->tree->pages_per_bnode; i++)
406 		if (node->page[i])
407 			put_page(node->page[i]);
408 	kfree(node);
409 }
410 
411 struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
412 {
413 	struct hfs_bnode *node;
414 	struct page **pagep;
415 	int i;
416 
417 	spin_lock(&tree->hash_lock);
418 	node = hfs_bnode_findhash(tree, num);
419 	spin_unlock(&tree->hash_lock);
420 	if (node) {
421 		pr_crit("new node %u already hashed?\n", num);
422 		WARN_ON(1);
423 		return node;
424 	}
425 	node = __hfs_bnode_create(tree, num);
426 	if (!node)
427 		return ERR_PTR(-ENOMEM);
428 	if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
429 		hfs_bnode_put(node);
430 		return ERR_PTR(-EIO);
431 	}
432 
433 	pagep = node->page;
434 	memzero_page(*pagep, node->page_offset,
435 		     min((int)PAGE_SIZE, (int)tree->node_size));
436 	set_page_dirty(*pagep);
437 	for (i = 1; i < tree->pages_per_bnode; i++) {
438 		memzero_page(*++pagep, 0, PAGE_SIZE);
439 		set_page_dirty(*pagep);
440 	}
441 	clear_bit(HFS_BNODE_NEW, &node->flags);
442 	wake_up(&node->lock_wq);
443 
444 	return node;
445 }
446 
447 void hfs_bnode_get(struct hfs_bnode *node)
448 {
449 	if (node) {
450 		atomic_inc(&node->refcnt);
451 		hfs_dbg(BNODE_REFS, "get_node(%d:%d): %d\n",
452 			node->tree->cnid, node->this,
453 			atomic_read(&node->refcnt));
454 	}
455 }
456 
457 /* Dispose of resources used by a node */
458 void hfs_bnode_put(struct hfs_bnode *node)
459 {
460 	if (node) {
461 		struct hfs_btree *tree = node->tree;
462 		int i;
463 
464 		hfs_dbg(BNODE_REFS, "put_node(%d:%d): %d\n",
465 			node->tree->cnid, node->this,
466 			atomic_read(&node->refcnt));
467 		BUG_ON(!atomic_read(&node->refcnt));
468 		if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
469 			return;
470 		for (i = 0; i < tree->pages_per_bnode; i++) {
471 			if (!node->page[i])
472 				continue;
473 			mark_page_accessed(node->page[i]);
474 		}
475 
476 		if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
477 			hfs_bnode_unhash(node);
478 			spin_unlock(&tree->hash_lock);
479 			hfs_bmap_free(node);
480 			hfs_bnode_free(node);
481 			return;
482 		}
483 		spin_unlock(&tree->hash_lock);
484 	}
485 }
486