xref: /linux/fs/hfsplus/bnode.c (revision 056a5087d87ead77dedbe9cf5bde53b7cd4b4651)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/hfsplus/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/string.h>
13 #include <linux/slab.h>
14 #include <linux/pagemap.h>
15 #include <linux/fs.h>
16 #include <linux/swap.h>
17 
18 #include "hfsplus_fs.h"
19 #include "hfsplus_raw.h"
20 
21 
22 /* Copy a specified range of bytes from the raw data of a node */
23 void hfs_bnode_read(struct hfs_bnode *node, void *buf, u32 off, u32 len)
24 {
25 	struct page **pagep;
26 	u32 l;
27 
28 	memset(buf, 0, len);
29 
30 	if (!is_bnode_offset_valid(node, off))
31 		return;
32 
33 	if (len == 0) {
34 		pr_err("requested zero length: "
35 		       "NODE: id %u, type %#x, height %u, "
36 		       "node_size %u, offset %u, len %u\n",
37 		       node->this, node->type, node->height,
38 		       node->tree->node_size, off, len);
39 		return;
40 	}
41 
42 	len = check_and_correct_requested_length(node, off, len);
43 
44 	off += node->page_offset;
45 	pagep = node->page + (off >> PAGE_SHIFT);
46 	off &= ~PAGE_MASK;
47 
48 	l = min_t(u32, len, PAGE_SIZE - off);
49 	memcpy_from_page(buf, *pagep, off, l);
50 
51 	while ((len -= l) != 0) {
52 		buf += l;
53 		l = min_t(u32, len, PAGE_SIZE);
54 		memcpy_from_page(buf, *++pagep, 0, l);
55 	}
56 }
57 
58 u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 off)
59 {
60 	__be16 data;
61 	/* TODO: optimize later... */
62 	hfs_bnode_read(node, &data, off, 2);
63 	return be16_to_cpu(data);
64 }
65 
66 u8 hfs_bnode_read_u8(struct hfs_bnode *node, u32 off)
67 {
68 	u8 data;
69 	/* TODO: optimize later... */
70 	hfs_bnode_read(node, &data, off, 1);
71 	return data;
72 }
73 
74 void hfs_bnode_read_key(struct hfs_bnode *node, void *key, u32 off)
75 {
76 	struct hfs_btree *tree;
77 	u32 key_len;
78 
79 	tree = node->tree;
80 	if (node->type == HFS_NODE_LEAF ||
81 	    tree->attributes & HFS_TREE_VARIDXKEYS ||
82 	    node->tree->cnid == HFSPLUS_ATTR_CNID)
83 		key_len = hfs_bnode_read_u16(node, off) + 2;
84 	else
85 		key_len = tree->max_key_len + 2;
86 
87 	if (key_len > sizeof(hfsplus_btree_key) || key_len < 1) {
88 		memset(key, 0, sizeof(hfsplus_btree_key));
89 		pr_err("hfsplus: Invalid key length: %u\n", key_len);
90 		return;
91 	}
92 
93 	hfs_bnode_read(node, key, off, key_len);
94 }
95 
96 void hfs_bnode_write(struct hfs_bnode *node, void *buf, u32 off, u32 len)
97 {
98 	struct page **pagep;
99 	u32 l;
100 
101 	if (!is_bnode_offset_valid(node, off))
102 		return;
103 
104 	if (len == 0) {
105 		pr_err("requested zero length: "
106 		       "NODE: id %u, type %#x, height %u, "
107 		       "node_size %u, offset %u, len %u\n",
108 		       node->this, node->type, node->height,
109 		       node->tree->node_size, off, len);
110 		return;
111 	}
112 
113 	len = check_and_correct_requested_length(node, off, len);
114 
115 	off += node->page_offset;
116 	pagep = node->page + (off >> PAGE_SHIFT);
117 	off &= ~PAGE_MASK;
118 
119 	l = min_t(u32, len, PAGE_SIZE - off);
120 	memcpy_to_page(*pagep, off, buf, l);
121 	set_page_dirty(*pagep);
122 
123 	while ((len -= l) != 0) {
124 		buf += l;
125 		l = min_t(u32, len, PAGE_SIZE);
126 		memcpy_to_page(*++pagep, 0, buf, l);
127 		set_page_dirty(*pagep);
128 	}
129 }
130 
131 void hfs_bnode_write_u16(struct hfs_bnode *node, u32 off, u16 data)
132 {
133 	__be16 v = cpu_to_be16(data);
134 	/* TODO: optimize later... */
135 	hfs_bnode_write(node, &v, off, 2);
136 }
137 
138 void hfs_bnode_clear(struct hfs_bnode *node, u32 off, u32 len)
139 {
140 	struct page **pagep;
141 	u32 l;
142 
143 	if (!is_bnode_offset_valid(node, off))
144 		return;
145 
146 	if (len == 0) {
147 		pr_err("requested zero length: "
148 		       "NODE: id %u, type %#x, height %u, "
149 		       "node_size %u, offset %u, len %u\n",
150 		       node->this, node->type, node->height,
151 		       node->tree->node_size, off, len);
152 		return;
153 	}
154 
155 	len = check_and_correct_requested_length(node, off, len);
156 
157 	off += node->page_offset;
158 	pagep = node->page + (off >> PAGE_SHIFT);
159 	off &= ~PAGE_MASK;
160 
161 	l = min_t(u32, len, PAGE_SIZE - off);
162 	memzero_page(*pagep, off, l);
163 	set_page_dirty(*pagep);
164 
165 	while ((len -= l) != 0) {
166 		l = min_t(u32, len, PAGE_SIZE);
167 		memzero_page(*++pagep, 0, l);
168 		set_page_dirty(*pagep);
169 	}
170 }
171 
172 void hfs_bnode_copy(struct hfs_bnode *dst_node, u32 dst,
173 		    struct hfs_bnode *src_node, u32 src, u32 len)
174 {
175 	struct page **src_page, **dst_page;
176 	u32 l;
177 
178 	hfs_dbg("dst %u, src %u, len %u\n", dst, src, len);
179 	if (!len)
180 		return;
181 
182 	len = check_and_correct_requested_length(src_node, src, len);
183 	len = check_and_correct_requested_length(dst_node, dst, len);
184 
185 	src += src_node->page_offset;
186 	dst += dst_node->page_offset;
187 	src_page = src_node->page + (src >> PAGE_SHIFT);
188 	src &= ~PAGE_MASK;
189 	dst_page = dst_node->page + (dst >> PAGE_SHIFT);
190 	dst &= ~PAGE_MASK;
191 
192 	if (src == dst) {
193 		l = min_t(u32, len, PAGE_SIZE - src);
194 		memcpy_page(*dst_page, src, *src_page, src, l);
195 		set_page_dirty(*dst_page);
196 
197 		while ((len -= l) != 0) {
198 			l = min_t(u32, len, PAGE_SIZE);
199 			memcpy_page(*++dst_page, 0, *++src_page, 0, l);
200 			set_page_dirty(*dst_page);
201 		}
202 	} else {
203 		void *src_ptr, *dst_ptr;
204 
205 		do {
206 			dst_ptr = kmap_local_page(*dst_page) + dst;
207 			src_ptr = kmap_local_page(*src_page) + src;
208 			if (PAGE_SIZE - src < PAGE_SIZE - dst) {
209 				l = PAGE_SIZE - src;
210 				src = 0;
211 				dst += l;
212 			} else {
213 				l = PAGE_SIZE - dst;
214 				src += l;
215 				dst = 0;
216 			}
217 			l = min(len, l);
218 			memcpy(dst_ptr, src_ptr, l);
219 			kunmap_local(src_ptr);
220 			set_page_dirty(*dst_page);
221 			kunmap_local(dst_ptr);
222 			if (!dst)
223 				dst_page++;
224 			else
225 				src_page++;
226 		} while ((len -= l));
227 	}
228 }
229 
230 void hfs_bnode_move(struct hfs_bnode *node, u32 dst, u32 src, u32 len)
231 {
232 	struct page **src_page, **dst_page;
233 	void *src_ptr, *dst_ptr;
234 	u32 l;
235 
236 	hfs_dbg("dst %u, src %u, len %u\n", dst, src, len);
237 	if (!len)
238 		return;
239 
240 	len = check_and_correct_requested_length(node, src, len);
241 	len = check_and_correct_requested_length(node, dst, len);
242 
243 	src += node->page_offset;
244 	dst += node->page_offset;
245 	if (dst > src) {
246 		src += len - 1;
247 		src_page = node->page + (src >> PAGE_SHIFT);
248 		src = (src & ~PAGE_MASK) + 1;
249 		dst += len - 1;
250 		dst_page = node->page + (dst >> PAGE_SHIFT);
251 		dst = (dst & ~PAGE_MASK) + 1;
252 
253 		if (src == dst) {
254 			while (src < len) {
255 				dst_ptr = kmap_local_page(*dst_page);
256 				src_ptr = kmap_local_page(*src_page);
257 				memmove(dst_ptr, src_ptr, src);
258 				kunmap_local(src_ptr);
259 				set_page_dirty(*dst_page);
260 				kunmap_local(dst_ptr);
261 				len -= src;
262 				src = PAGE_SIZE;
263 				src_page--;
264 				dst_page--;
265 			}
266 			src -= len;
267 			dst_ptr = kmap_local_page(*dst_page);
268 			src_ptr = kmap_local_page(*src_page);
269 			memmove(dst_ptr + src, src_ptr + src, len);
270 			kunmap_local(src_ptr);
271 			set_page_dirty(*dst_page);
272 			kunmap_local(dst_ptr);
273 		} else {
274 			do {
275 				dst_ptr = kmap_local_page(*dst_page) + dst;
276 				src_ptr = kmap_local_page(*src_page) + src;
277 				if (src < dst) {
278 					l = src;
279 					src = PAGE_SIZE;
280 					dst -= l;
281 				} else {
282 					l = dst;
283 					src -= l;
284 					dst = PAGE_SIZE;
285 				}
286 				l = min(len, l);
287 				memmove(dst_ptr - l, src_ptr - l, l);
288 				kunmap_local(src_ptr);
289 				set_page_dirty(*dst_page);
290 				kunmap_local(dst_ptr);
291 				if (dst == PAGE_SIZE)
292 					dst_page--;
293 				else
294 					src_page--;
295 			} while ((len -= l));
296 		}
297 	} else {
298 		src_page = node->page + (src >> PAGE_SHIFT);
299 		src &= ~PAGE_MASK;
300 		dst_page = node->page + (dst >> PAGE_SHIFT);
301 		dst &= ~PAGE_MASK;
302 
303 		if (src == dst) {
304 			l = min_t(u32, len, PAGE_SIZE - src);
305 
306 			dst_ptr = kmap_local_page(*dst_page) + src;
307 			src_ptr = kmap_local_page(*src_page) + src;
308 			memmove(dst_ptr, src_ptr, l);
309 			kunmap_local(src_ptr);
310 			set_page_dirty(*dst_page);
311 			kunmap_local(dst_ptr);
312 
313 			while ((len -= l) != 0) {
314 				l = min_t(u32, len, PAGE_SIZE);
315 				dst_ptr = kmap_local_page(*++dst_page);
316 				src_ptr = kmap_local_page(*++src_page);
317 				memmove(dst_ptr, src_ptr, l);
318 				kunmap_local(src_ptr);
319 				set_page_dirty(*dst_page);
320 				kunmap_local(dst_ptr);
321 			}
322 		} else {
323 			do {
324 				dst_ptr = kmap_local_page(*dst_page) + dst;
325 				src_ptr = kmap_local_page(*src_page) + src;
326 				if (PAGE_SIZE - src <
327 						PAGE_SIZE - dst) {
328 					l = PAGE_SIZE - src;
329 					src = 0;
330 					dst += l;
331 				} else {
332 					l = PAGE_SIZE - dst;
333 					src += l;
334 					dst = 0;
335 				}
336 				l = min(len, l);
337 				memmove(dst_ptr, src_ptr, l);
338 				kunmap_local(src_ptr);
339 				set_page_dirty(*dst_page);
340 				kunmap_local(dst_ptr);
341 				if (!dst)
342 					dst_page++;
343 				else
344 					src_page++;
345 			} while ((len -= l));
346 		}
347 	}
348 }
349 
350 void hfs_bnode_dump(struct hfs_bnode *node)
351 {
352 	struct hfs_bnode_desc desc;
353 	__be32 cnid;
354 	int i, off, key_off;
355 
356 	hfs_dbg("node %d\n", node->this);
357 	hfs_bnode_read(node, &desc, 0, sizeof(desc));
358 	hfs_dbg("next %d, prev %d, type %d, height %d, num_recs %d\n",
359 		be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
360 		desc.type, desc.height, be16_to_cpu(desc.num_recs));
361 
362 	off = node->tree->node_size - 2;
363 	for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
364 		key_off = hfs_bnode_read_u16(node, off);
365 		hfs_dbg(" key_off %d", key_off);
366 		if (i && node->type == HFS_NODE_INDEX) {
367 			int tmp;
368 
369 			if (node->tree->attributes & HFS_TREE_VARIDXKEYS ||
370 					node->tree->cnid == HFSPLUS_ATTR_CNID)
371 				tmp = hfs_bnode_read_u16(node, key_off) + 2;
372 			else
373 				tmp = node->tree->max_key_len + 2;
374 			hfs_dbg(" (%d", tmp);
375 			hfs_bnode_read(node, &cnid, key_off + tmp, 4);
376 			hfs_dbg(", cnid %d)", be32_to_cpu(cnid));
377 		} else if (i && node->type == HFS_NODE_LEAF) {
378 			int tmp;
379 
380 			tmp = hfs_bnode_read_u16(node, key_off);
381 			hfs_dbg(" (%d)", tmp);
382 		}
383 	}
384 	hfs_dbg("\n");
385 }
386 
387 void hfs_bnode_unlink(struct hfs_bnode *node)
388 {
389 	struct hfs_btree *tree;
390 	struct hfs_bnode *tmp;
391 	__be32 cnid;
392 
393 	tree = node->tree;
394 	if (node->prev) {
395 		tmp = hfs_bnode_find(tree, node->prev);
396 		if (IS_ERR(tmp))
397 			return;
398 		tmp->next = node->next;
399 		cnid = cpu_to_be32(tmp->next);
400 		hfs_bnode_write(tmp, &cnid,
401 			offsetof(struct hfs_bnode_desc, next), 4);
402 		hfs_bnode_put(tmp);
403 	} else if (node->type == HFS_NODE_LEAF)
404 		tree->leaf_head = node->next;
405 
406 	if (node->next) {
407 		tmp = hfs_bnode_find(tree, node->next);
408 		if (IS_ERR(tmp))
409 			return;
410 		tmp->prev = node->prev;
411 		cnid = cpu_to_be32(tmp->prev);
412 		hfs_bnode_write(tmp, &cnid,
413 			offsetof(struct hfs_bnode_desc, prev), 4);
414 		hfs_bnode_put(tmp);
415 	} else if (node->type == HFS_NODE_LEAF)
416 		tree->leaf_tail = node->prev;
417 
418 	/* move down? */
419 	if (!node->prev && !node->next)
420 		hfs_dbg("btree delete level\n");
421 	if (!node->parent) {
422 		tree->root = 0;
423 		tree->depth = 0;
424 	}
425 
426 	spin_lock(&tree->hash_lock);
427 	set_bit(HFS_BNODE_DELETED, &node->flags);
428 	spin_unlock(&tree->hash_lock);
429 }
430 
431 static inline int hfs_bnode_hash(u32 num)
432 {
433 	num = (num >> 16) + num;
434 	num += num >> 8;
435 	return num & (NODE_HASH_SIZE - 1);
436 }
437 
438 struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
439 {
440 	struct hfs_bnode *node;
441 
442 	if (cnid >= tree->node_count) {
443 		pr_err("request for non-existent node %d in B*Tree\n",
444 		       cnid);
445 		return NULL;
446 	}
447 
448 	for (node = tree->node_hash[hfs_bnode_hash(cnid)];
449 			node; node = node->next_hash)
450 		if (node->this == cnid)
451 			return node;
452 	return NULL;
453 }
454 
455 static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
456 {
457 	struct hfs_bnode *node, *node2;
458 	struct address_space *mapping;
459 	struct page *page;
460 	int block, i, hash;
461 	loff_t off;
462 
463 	if (cnid >= tree->node_count) {
464 		pr_err("request for non-existent node %d in B*Tree\n",
465 		       cnid);
466 		return NULL;
467 	}
468 
469 	node = kzalloc_flex(*node, page, tree->pages_per_bnode);
470 	if (!node)
471 		return NULL;
472 	node->tree = tree;
473 	node->this = cnid;
474 	set_bit(HFS_BNODE_NEW, &node->flags);
475 	atomic_set(&node->refcnt, 1);
476 	hfs_dbg("cnid %d, node %d, refcnt 1\n",
477 		node->tree->cnid, node->this);
478 	init_waitqueue_head(&node->lock_wq);
479 	spin_lock(&tree->hash_lock);
480 	node2 = hfs_bnode_findhash(tree, cnid);
481 	if (!node2) {
482 		hash = hfs_bnode_hash(cnid);
483 		node->next_hash = tree->node_hash[hash];
484 		tree->node_hash[hash] = node;
485 		tree->node_hash_cnt++;
486 	} else {
487 		hfs_bnode_get(node2);
488 		spin_unlock(&tree->hash_lock);
489 		kfree(node);
490 		wait_event(node2->lock_wq,
491 			!test_bit(HFS_BNODE_NEW, &node2->flags));
492 		return node2;
493 	}
494 	spin_unlock(&tree->hash_lock);
495 
496 	mapping = tree->inode->i_mapping;
497 	off = (loff_t)cnid << tree->node_size_shift;
498 	block = off >> PAGE_SHIFT;
499 	node->page_offset = off & ~PAGE_MASK;
500 	for (i = 0; i < tree->pages_per_bnode; block++, i++) {
501 		page = read_mapping_page(mapping, block, NULL);
502 		if (IS_ERR(page))
503 			goto fail;
504 		node->page[i] = page;
505 	}
506 
507 	return node;
508 fail:
509 	set_bit(HFS_BNODE_ERROR, &node->flags);
510 	return node;
511 }
512 
513 void hfs_bnode_unhash(struct hfs_bnode *node)
514 {
515 	struct hfs_bnode **p;
516 
517 	hfs_dbg("cnid %d, node %d, refcnt %d\n",
518 		node->tree->cnid, node->this, atomic_read(&node->refcnt));
519 	for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
520 	     *p && *p != node; p = &(*p)->next_hash)
521 		;
522 	BUG_ON(!*p);
523 	*p = node->next_hash;
524 	node->tree->node_hash_cnt--;
525 }
526 
527 /* Load a particular node out of a tree */
528 struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
529 {
530 	struct hfs_bnode *node;
531 	struct hfs_bnode_desc *desc;
532 	int i, rec_off, off, next_off;
533 	int entry_size, key_size;
534 
535 	spin_lock(&tree->hash_lock);
536 	node = hfs_bnode_findhash(tree, num);
537 	if (node) {
538 		hfs_bnode_get(node);
539 		spin_unlock(&tree->hash_lock);
540 		wait_event(node->lock_wq,
541 			!test_bit(HFS_BNODE_NEW, &node->flags));
542 		if (test_bit(HFS_BNODE_ERROR, &node->flags))
543 			goto node_error;
544 		return node;
545 	}
546 	spin_unlock(&tree->hash_lock);
547 	node = __hfs_bnode_create(tree, num);
548 	if (!node)
549 		return ERR_PTR(-ENOMEM);
550 	if (test_bit(HFS_BNODE_ERROR, &node->flags))
551 		goto node_error;
552 	if (!test_bit(HFS_BNODE_NEW, &node->flags))
553 		return node;
554 
555 	desc = (struct hfs_bnode_desc *)(kmap_local_page(node->page[0]) +
556 							 node->page_offset);
557 	node->prev = be32_to_cpu(desc->prev);
558 	node->next = be32_to_cpu(desc->next);
559 	node->num_recs = be16_to_cpu(desc->num_recs);
560 	node->type = desc->type;
561 	node->height = desc->height;
562 	kunmap_local(desc);
563 
564 	switch (node->type) {
565 	case HFS_NODE_HEADER:
566 	case HFS_NODE_MAP:
567 		if (node->height != 0)
568 			goto node_error;
569 		break;
570 	case HFS_NODE_LEAF:
571 		if (node->height != 1)
572 			goto node_error;
573 		break;
574 	case HFS_NODE_INDEX:
575 		if (node->height <= 1 || node->height > tree->depth)
576 			goto node_error;
577 		break;
578 	default:
579 		goto node_error;
580 	}
581 
582 	rec_off = tree->node_size - 2;
583 	off = hfs_bnode_read_u16(node, rec_off);
584 	if (off != sizeof(struct hfs_bnode_desc))
585 		goto node_error;
586 	for (i = 1; i <= node->num_recs; off = next_off, i++) {
587 		rec_off -= 2;
588 		next_off = hfs_bnode_read_u16(node, rec_off);
589 		if (next_off <= off ||
590 		    next_off > tree->node_size ||
591 		    next_off & 1)
592 			goto node_error;
593 		entry_size = next_off - off;
594 		if (node->type != HFS_NODE_INDEX &&
595 		    node->type != HFS_NODE_LEAF)
596 			continue;
597 		key_size = hfs_bnode_read_u16(node, off) + 2;
598 		if (key_size >= entry_size || key_size & 1)
599 			goto node_error;
600 	}
601 	clear_bit(HFS_BNODE_NEW, &node->flags);
602 	wake_up(&node->lock_wq);
603 	return node;
604 
605 node_error:
606 	set_bit(HFS_BNODE_ERROR, &node->flags);
607 	clear_bit(HFS_BNODE_NEW, &node->flags);
608 	wake_up(&node->lock_wq);
609 	hfs_bnode_put(node);
610 	return ERR_PTR(-EIO);
611 }
612 
613 void hfs_bnode_free(struct hfs_bnode *node)
614 {
615 	int i;
616 
617 	for (i = 0; i < node->tree->pages_per_bnode; i++)
618 		if (node->page[i])
619 			put_page(node->page[i]);
620 	kfree(node);
621 }
622 
623 struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
624 {
625 	struct hfs_bnode *node;
626 	struct page **pagep;
627 	int i;
628 
629 	spin_lock(&tree->hash_lock);
630 	node = hfs_bnode_findhash(tree, num);
631 	spin_unlock(&tree->hash_lock);
632 	if (node) {
633 		pr_crit("new node %u already hashed?\n", num);
634 		WARN_ON(1);
635 		return ERR_PTR(-EEXIST);
636 	}
637 	node = __hfs_bnode_create(tree, num);
638 	if (!node)
639 		return ERR_PTR(-ENOMEM);
640 	if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
641 		hfs_bnode_put(node);
642 		return ERR_PTR(-EIO);
643 	}
644 
645 	pagep = node->page;
646 	memzero_page(*pagep, node->page_offset,
647 		     min_t(int, PAGE_SIZE, tree->node_size));
648 	set_page_dirty(*pagep);
649 	for (i = 1; i < tree->pages_per_bnode; i++) {
650 		memzero_page(*++pagep, 0, PAGE_SIZE);
651 		set_page_dirty(*pagep);
652 	}
653 	clear_bit(HFS_BNODE_NEW, &node->flags);
654 	wake_up(&node->lock_wq);
655 
656 	return node;
657 }
658 
659 void hfs_bnode_get(struct hfs_bnode *node)
660 {
661 	if (node) {
662 		atomic_inc(&node->refcnt);
663 		hfs_dbg("cnid %d, node %d, refcnt %d\n",
664 			node->tree->cnid, node->this,
665 			atomic_read(&node->refcnt));
666 	}
667 }
668 
669 /* Dispose of resources used by a node */
670 void hfs_bnode_put(struct hfs_bnode *node)
671 {
672 	if (node) {
673 		struct hfs_btree *tree = node->tree;
674 		int i;
675 
676 		hfs_dbg("cnid %d, node %d, refcnt %d\n",
677 			node->tree->cnid, node->this,
678 			atomic_read(&node->refcnt));
679 		BUG_ON(!atomic_read(&node->refcnt));
680 		if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
681 			return;
682 		for (i = 0; i < tree->pages_per_bnode; i++) {
683 			if (!node->page[i])
684 				continue;
685 			mark_page_accessed(node->page[i]);
686 		}
687 
688 		if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
689 			hfs_bnode_unhash(node);
690 			spin_unlock(&tree->hash_lock);
691 			if (hfs_bnode_need_zeroout(tree))
692 				hfs_bnode_clear(node, 0, tree->node_size);
693 			hfs_bmap_free(node);
694 			hfs_bnode_free(node);
695 			return;
696 		}
697 		spin_unlock(&tree->hash_lock);
698 	}
699 }
700 
701 /*
702  * Unused nodes have to be zeroed if this is the catalog tree and
703  * a corresponding flag in the volume header is set.
704  */
705 bool hfs_bnode_need_zeroout(struct hfs_btree *tree)
706 {
707 	struct super_block *sb = tree->inode->i_sb;
708 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
709 	const u32 volume_attr = be32_to_cpu(sbi->s_vhdr->attributes);
710 
711 	return volume_attr & HFSPLUS_VOL_UNUSED_NODE_FIX;
712 }
713