xref: /linux/fs/hfs/bnode.c (revision 0be3ff0c) 
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 	void *vaddr;
25 
26 	off += node->page_offset;
27 	pagenum = off >> PAGE_SHIFT;
28 	off &= ~PAGE_MASK; /* compute page offset for the first page */
29 
30 	for (bytes_read = 0; bytes_read < len; bytes_read += bytes_to_read) {
31 		if (pagenum >= node->tree->pages_per_bnode)
32 			break;
33 		page = node->page[pagenum];
34 		bytes_to_read = min_t(int, len - bytes_read, PAGE_SIZE - off);
35 
36 		vaddr = kmap_atomic(page);
37 		memcpy(buf + bytes_read, vaddr + off, bytes_to_read);
38 		kunmap_atomic(vaddr);
39 
40 		pagenum++;
41 		off = 0; /* page offset only applies to the first page */
42 	}
43 }
44 
45 u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)
46 {
47 	__be16 data;
48 	// optimize later...
49 	hfs_bnode_read(node, &data, off, 2);
50 	return be16_to_cpu(data);
51 }
52 
53 u8 hfs_bnode_read_u8(struct hfs_bnode *node, int off)
54 {
55 	u8 data;
56 	// optimize later...
57 	hfs_bnode_read(node, &data, off, 1);
58 	return data;
59 }
60 
61 void hfs_bnode_read_key(struct hfs_bnode *node, void *key, int off)
62 {
63 	struct hfs_btree *tree;
64 	int key_len;
65 
66 	tree = node->tree;
67 	if (node->type == HFS_NODE_LEAF ||
68 	    tree->attributes & HFS_TREE_VARIDXKEYS)
69 		key_len = hfs_bnode_read_u8(node, off) + 1;
70 	else
71 		key_len = tree->max_key_len + 1;
72 
73 	hfs_bnode_read(node, key, off, key_len);
74 }
75 
76 void hfs_bnode_write(struct hfs_bnode *node, void *buf, int off, int len)
77 {
78 	struct page *page;
79 
80 	off += node->page_offset;
81 	page = node->page[0];
82 
83 	memcpy(kmap(page) + off, buf, len);
84 	kunmap(page);
85 	set_page_dirty(page);
86 }
87 
88 void hfs_bnode_write_u16(struct hfs_bnode *node, int off, u16 data)
89 {
90 	__be16 v = cpu_to_be16(data);
91 	// optimize later...
92 	hfs_bnode_write(node, &v, off, 2);
93 }
94 
95 void hfs_bnode_write_u8(struct hfs_bnode *node, int off, u8 data)
96 {
97 	// optimize later...
98 	hfs_bnode_write(node, &data, off, 1);
99 }
100 
101 void hfs_bnode_clear(struct hfs_bnode *node, int off, int len)
102 {
103 	struct page *page;
104 
105 	off += node->page_offset;
106 	page = node->page[0];
107 
108 	memset(kmap(page) + off, 0, len);
109 	kunmap(page);
110 	set_page_dirty(page);
111 }
112 
113 void hfs_bnode_copy(struct hfs_bnode *dst_node, int dst,
114 		struct hfs_bnode *src_node, int src, int len)
115 {
116 	struct page *src_page, *dst_page;
117 
118 	hfs_dbg(BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
119 	if (!len)
120 		return;
121 	src += src_node->page_offset;
122 	dst += dst_node->page_offset;
123 	src_page = src_node->page[0];
124 	dst_page = dst_node->page[0];
125 
126 	memcpy(kmap(dst_page) + dst, kmap(src_page) + src, len);
127 	kunmap(src_page);
128 	kunmap(dst_page);
129 	set_page_dirty(dst_page);
130 }
131 
132 void hfs_bnode_move(struct hfs_bnode *node, int dst, int src, int len)
133 {
134 	struct page *page;
135 	void *ptr;
136 
137 	hfs_dbg(BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
138 	if (!len)
139 		return;
140 	src += node->page_offset;
141 	dst += node->page_offset;
142 	page = node->page[0];
143 	ptr = kmap(page);
144 	memmove(ptr + dst, ptr + src, len);
145 	kunmap(page);
146 	set_page_dirty(page);
147 }
148 
149 void hfs_bnode_dump(struct hfs_bnode *node)
150 {
151 	struct hfs_bnode_desc desc;
152 	__be32 cnid;
153 	int i, off, key_off;
154 
155 	hfs_dbg(BNODE_MOD, "bnode: %d\n", node->this);
156 	hfs_bnode_read(node, &desc, 0, sizeof(desc));
157 	hfs_dbg(BNODE_MOD, "%d, %d, %d, %d, %d\n",
158 		be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
159 		desc.type, desc.height, be16_to_cpu(desc.num_recs));
160 
161 	off = node->tree->node_size - 2;
162 	for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
163 		key_off = hfs_bnode_read_u16(node, off);
164 		hfs_dbg_cont(BNODE_MOD, " %d", key_off);
165 		if (i && node->type == HFS_NODE_INDEX) {
166 			int tmp;
167 
168 			if (node->tree->attributes & HFS_TREE_VARIDXKEYS)
169 				tmp = (hfs_bnode_read_u8(node, key_off) | 1) + 1;
170 			else
171 				tmp = node->tree->max_key_len + 1;
172 			hfs_dbg_cont(BNODE_MOD, " (%d,%d",
173 				     tmp, hfs_bnode_read_u8(node, key_off));
174 			hfs_bnode_read(node, &cnid, key_off + tmp, 4);
175 			hfs_dbg_cont(BNODE_MOD, ",%d)", be32_to_cpu(cnid));
176 		} else if (i && node->type == HFS_NODE_LEAF) {
177 			int tmp;
178 
179 			tmp = hfs_bnode_read_u8(node, key_off);
180 			hfs_dbg_cont(BNODE_MOD, " (%d)", tmp);
181 		}
182 	}
183 	hfs_dbg_cont(BNODE_MOD, "\n");
184 }
185 
186 void hfs_bnode_unlink(struct hfs_bnode *node)
187 {
188 	struct hfs_btree *tree;
189 	struct hfs_bnode *tmp;
190 	__be32 cnid;
191 
192 	tree = node->tree;
193 	if (node->prev) {
194 		tmp = hfs_bnode_find(tree, node->prev);
195 		if (IS_ERR(tmp))
196 			return;
197 		tmp->next = node->next;
198 		cnid = cpu_to_be32(tmp->next);
199 		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
200 		hfs_bnode_put(tmp);
201 	} else if (node->type == HFS_NODE_LEAF)
202 		tree->leaf_head = node->next;
203 
204 	if (node->next) {
205 		tmp = hfs_bnode_find(tree, node->next);
206 		if (IS_ERR(tmp))
207 			return;
208 		tmp->prev = node->prev;
209 		cnid = cpu_to_be32(tmp->prev);
210 		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
211 		hfs_bnode_put(tmp);
212 	} else if (node->type == HFS_NODE_LEAF)
213 		tree->leaf_tail = node->prev;
214 
215 	// move down?
216 	if (!node->prev && !node->next) {
217 		printk(KERN_DEBUG "hfs_btree_del_level\n");
218 	}
219 	if (!node->parent) {
220 		tree->root = 0;
221 		tree->depth = 0;
222 	}
223 	set_bit(HFS_BNODE_DELETED, &node->flags);
224 }
225 
226 static inline int hfs_bnode_hash(u32 num)
227 {
228 	num = (num >> 16) + num;
229 	num += num >> 8;
230 	return num & (NODE_HASH_SIZE - 1);
231 }
232 
233 struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
234 {
235 	struct hfs_bnode *node;
236 
237 	if (cnid >= tree->node_count) {
238 		pr_err("request for non-existent node %d in B*Tree\n", cnid);
239 		return NULL;
240 	}
241 
242 	for (node = tree->node_hash[hfs_bnode_hash(cnid)];
243 	     node; node = node->next_hash) {
244 		if (node->this == cnid) {
245 			return node;
246 		}
247 	}
248 	return NULL;
249 }
250 
251 static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
252 {
253 	struct hfs_bnode *node, *node2;
254 	struct address_space *mapping;
255 	struct page *page;
256 	int size, block, i, hash;
257 	loff_t off;
258 
259 	if (cnid >= tree->node_count) {
260 		pr_err("request for non-existent node %d in B*Tree\n", cnid);
261 		return NULL;
262 	}
263 
264 	size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
265 		sizeof(struct page *);
266 	node = kzalloc(size, GFP_KERNEL);
267 	if (!node)
268 		return NULL;
269 	node->tree = tree;
270 	node->this = cnid;
271 	set_bit(HFS_BNODE_NEW, &node->flags);
272 	atomic_set(&node->refcnt, 1);
273 	hfs_dbg(BNODE_REFS, "new_node(%d:%d): 1\n",
274 		node->tree->cnid, node->this);
275 	init_waitqueue_head(&node->lock_wq);
276 	spin_lock(&tree->hash_lock);
277 	node2 = hfs_bnode_findhash(tree, cnid);
278 	if (!node2) {
279 		hash = hfs_bnode_hash(cnid);
280 		node->next_hash = tree->node_hash[hash];
281 		tree->node_hash[hash] = node;
282 		tree->node_hash_cnt++;
283 	} else {
284 		spin_unlock(&tree->hash_lock);
285 		kfree(node);
286 		wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
287 		return node2;
288 	}
289 	spin_unlock(&tree->hash_lock);
290 
291 	mapping = tree->inode->i_mapping;
292 	off = (loff_t)cnid * tree->node_size;
293 	block = off >> PAGE_SHIFT;
294 	node->page_offset = off & ~PAGE_MASK;
295 	for (i = 0; i < tree->pages_per_bnode; i++) {
296 		page = read_mapping_page(mapping, block++, NULL);
297 		if (IS_ERR(page))
298 			goto fail;
299 		if (PageError(page)) {
300 			put_page(page);
301 			goto fail;
302 		}
303 		node->page[i] = page;
304 	}
305 
306 	return node;
307 fail:
308 	set_bit(HFS_BNODE_ERROR, &node->flags);
309 	return node;
310 }
311 
312 void hfs_bnode_unhash(struct hfs_bnode *node)
313 {
314 	struct hfs_bnode **p;
315 
316 	hfs_dbg(BNODE_REFS, "remove_node(%d:%d): %d\n",
317 		node->tree->cnid, node->this, atomic_read(&node->refcnt));
318 	for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
319 	     *p && *p != node; p = &(*p)->next_hash)
320 		;
321 	BUG_ON(!*p);
322 	*p = node->next_hash;
323 	node->tree->node_hash_cnt--;
324 }
325 
326 /* Load a particular node out of a tree */
327 struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
328 {
329 	struct hfs_bnode *node;
330 	struct hfs_bnode_desc *desc;
331 	int i, rec_off, off, next_off;
332 	int entry_size, key_size;
333 
334 	spin_lock(&tree->hash_lock);
335 	node = hfs_bnode_findhash(tree, num);
336 	if (node) {
337 		hfs_bnode_get(node);
338 		spin_unlock(&tree->hash_lock);
339 		wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
340 		if (test_bit(HFS_BNODE_ERROR, &node->flags))
341 			goto node_error;
342 		return node;
343 	}
344 	spin_unlock(&tree->hash_lock);
345 	node = __hfs_bnode_create(tree, num);
346 	if (!node)
347 		return ERR_PTR(-ENOMEM);
348 	if (test_bit(HFS_BNODE_ERROR, &node->flags))
349 		goto node_error;
350 	if (!test_bit(HFS_BNODE_NEW, &node->flags))
351 		return node;
352 
353 	desc = (struct hfs_bnode_desc *)(kmap(node->page[0]) + node->page_offset);
354 	node->prev = be32_to_cpu(desc->prev);
355 	node->next = be32_to_cpu(desc->next);
356 	node->num_recs = be16_to_cpu(desc->num_recs);
357 	node->type = desc->type;
358 	node->height = desc->height;
359 	kunmap(node->page[0]);
360 
361 	switch (node->type) {
362 	case HFS_NODE_HEADER:
363 	case HFS_NODE_MAP:
364 		if (node->height != 0)
365 			goto node_error;
366 		break;
367 	case HFS_NODE_LEAF:
368 		if (node->height != 1)
369 			goto node_error;
370 		break;
371 	case HFS_NODE_INDEX:
372 		if (node->height <= 1 || node->height > tree->depth)
373 			goto node_error;
374 		break;
375 	default:
376 		goto node_error;
377 	}
378 
379 	rec_off = tree->node_size - 2;
380 	off = hfs_bnode_read_u16(node, rec_off);
381 	if (off != sizeof(struct hfs_bnode_desc))
382 		goto node_error;
383 	for (i = 1; i <= node->num_recs; off = next_off, i++) {
384 		rec_off -= 2;
385 		next_off = hfs_bnode_read_u16(node, rec_off);
386 		if (next_off <= off ||
387 		    next_off > tree->node_size ||
388 		    next_off & 1)
389 			goto node_error;
390 		entry_size = next_off - off;
391 		if (node->type != HFS_NODE_INDEX &&
392 		    node->type != HFS_NODE_LEAF)
393 			continue;
394 		key_size = hfs_bnode_read_u8(node, off) + 1;
395 		if (key_size >= entry_size /*|| key_size & 1*/)
396 			goto node_error;
397 	}
398 	clear_bit(HFS_BNODE_NEW, &node->flags);
399 	wake_up(&node->lock_wq);
400 	return node;
401 
402 node_error:
403 	set_bit(HFS_BNODE_ERROR, &node->flags);
404 	clear_bit(HFS_BNODE_NEW, &node->flags);
405 	wake_up(&node->lock_wq);
406 	hfs_bnode_put(node);
407 	return ERR_PTR(-EIO);
408 }
409 
410 void hfs_bnode_free(struct hfs_bnode *node)
411 {
412 	int i;
413 
414 	for (i = 0; i < node->tree->pages_per_bnode; i++)
415 		if (node->page[i])
416 			put_page(node->page[i]);
417 	kfree(node);
418 }
419 
420 struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
421 {
422 	struct hfs_bnode *node;
423 	struct page **pagep;
424 	int i;
425 
426 	spin_lock(&tree->hash_lock);
427 	node = hfs_bnode_findhash(tree, num);
428 	spin_unlock(&tree->hash_lock);
429 	if (node) {
430 		pr_crit("new node %u already hashed?\n", num);
431 		WARN_ON(1);
432 		return node;
433 	}
434 	node = __hfs_bnode_create(tree, num);
435 	if (!node)
436 		return ERR_PTR(-ENOMEM);
437 	if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
438 		hfs_bnode_put(node);
439 		return ERR_PTR(-EIO);
440 	}
441 
442 	pagep = node->page;
443 	memset(kmap(*pagep) + node->page_offset, 0,
444 	       min((int)PAGE_SIZE, (int)tree->node_size));
445 	set_page_dirty(*pagep);
446 	kunmap(*pagep);
447 	for (i = 1; i < tree->pages_per_bnode; i++) {
448 		memset(kmap(*++pagep), 0, PAGE_SIZE);
449 		set_page_dirty(*pagep);
450 		kunmap(*pagep);
451 	}
452 	clear_bit(HFS_BNODE_NEW, &node->flags);
453 	wake_up(&node->lock_wq);
454 
455 	return node;
456 }
457 
458 void hfs_bnode_get(struct hfs_bnode *node)
459 {
460 	if (node) {
461 		atomic_inc(&node->refcnt);
462 		hfs_dbg(BNODE_REFS, "get_node(%d:%d): %d\n",
463 			node->tree->cnid, node->this,
464 			atomic_read(&node->refcnt));
465 	}
466 }
467 
468 /* Dispose of resources used by a node */
469 void hfs_bnode_put(struct hfs_bnode *node)
470 {
471 	if (node) {
472 		struct hfs_btree *tree = node->tree;
473 		int i;
474 
475 		hfs_dbg(BNODE_REFS, "put_node(%d:%d): %d\n",
476 			node->tree->cnid, node->this,
477 			atomic_read(&node->refcnt));
478 		BUG_ON(!atomic_read(&node->refcnt));
479 		if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
480 			return;
481 		for (i = 0; i < tree->pages_per_bnode; i++) {
482 			if (!node->page[i])
483 				continue;
484 			mark_page_accessed(node->page[i]);
485 		}
486 
487 		if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
488 			hfs_bnode_unhash(node);
489 			spin_unlock(&tree->hash_lock);
490 			hfs_bmap_free(node);
491 			hfs_bnode_free(node);
492 			return;
493 		}
494 		spin_unlock(&tree->hash_lock);
495 	}
496 }
497