1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/hfs/btree.c
4  *
5  * Copyright (C) 2001
6  * Brad Boyer (flar@allandria.com)
7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
8  *
9  * Handle opening/closing btree
10  */
11 
12 #include <linux/pagemap.h>
13 #include <linux/slab.h>
14 #include <linux/log2.h>
15 
16 #include "btree.h"
17 
18 /* Get a reference to a B*Tree and do some initial checks */
hfs_btree_open(struct super_block * sb,u32 id,btree_keycmp keycmp)19 struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp keycmp)
20 {
21 	struct hfs_btree *tree;
22 	struct hfs_btree_header_rec *head;
23 	struct address_space *mapping;
24 	struct page *page;
25 	unsigned int size;
26 
27 	tree = kzalloc(sizeof(*tree), GFP_KERNEL);
28 	if (!tree)
29 		return NULL;
30 
31 	mutex_init(&tree->tree_lock);
32 	spin_lock_init(&tree->hash_lock);
33 	/* Set the correct compare function */
34 	tree->sb = sb;
35 	tree->cnid = id;
36 	tree->keycmp = keycmp;
37 
38 	tree->inode = iget_locked(sb, id);
39 	if (!tree->inode)
40 		goto free_tree;
41 	BUG_ON(!(tree->inode->i_state & I_NEW));
42 	{
43 	struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
44 	HFS_I(tree->inode)->flags = 0;
45 	mutex_init(&HFS_I(tree->inode)->extents_lock);
46 	switch (id) {
47 	case HFS_EXT_CNID:
48 		hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
49 				    mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
50 		if (HFS_I(tree->inode)->alloc_blocks >
51 					HFS_I(tree->inode)->first_blocks) {
52 			pr_err("invalid btree extent records\n");
53 			unlock_new_inode(tree->inode);
54 			goto free_inode;
55 		}
56 
57 		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
58 		break;
59 	case HFS_CAT_CNID:
60 		hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
61 				    mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
62 
63 		if (!HFS_I(tree->inode)->first_blocks) {
64 			pr_err("invalid btree extent records (0 size)\n");
65 			unlock_new_inode(tree->inode);
66 			goto free_inode;
67 		}
68 
69 		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
70 		break;
71 	default:
72 		BUG();
73 	}
74 	}
75 	unlock_new_inode(tree->inode);
76 
77 	mapping = tree->inode->i_mapping;
78 	page = read_mapping_page(mapping, 0, NULL);
79 	if (IS_ERR(page))
80 		goto free_inode;
81 
82 	/* Load the header */
83 	head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
84 	tree->root = be32_to_cpu(head->root);
85 	tree->leaf_count = be32_to_cpu(head->leaf_count);
86 	tree->leaf_head = be32_to_cpu(head->leaf_head);
87 	tree->leaf_tail = be32_to_cpu(head->leaf_tail);
88 	tree->node_count = be32_to_cpu(head->node_count);
89 	tree->free_nodes = be32_to_cpu(head->free_nodes);
90 	tree->attributes = be32_to_cpu(head->attributes);
91 	tree->node_size = be16_to_cpu(head->node_size);
92 	tree->max_key_len = be16_to_cpu(head->max_key_len);
93 	tree->depth = be16_to_cpu(head->depth);
94 
95 	size = tree->node_size;
96 	if (!is_power_of_2(size))
97 		goto fail_page;
98 	if (!tree->node_count)
99 		goto fail_page;
100 	switch (id) {
101 	case HFS_EXT_CNID:
102 		if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
103 			pr_err("invalid extent max_key_len %d\n",
104 			       tree->max_key_len);
105 			goto fail_page;
106 		}
107 		break;
108 	case HFS_CAT_CNID:
109 		if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
110 			pr_err("invalid catalog max_key_len %d\n",
111 			       tree->max_key_len);
112 			goto fail_page;
113 		}
114 		break;
115 	default:
116 		BUG();
117 	}
118 
119 	tree->node_size_shift = ffs(size) - 1;
120 	tree->pages_per_bnode = (tree->node_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
121 
122 	kunmap(page);
123 	put_page(page);
124 	return tree;
125 
126 fail_page:
127 	put_page(page);
128 free_inode:
129 	tree->inode->i_mapping->a_ops = &hfs_aops;
130 	iput(tree->inode);
131 free_tree:
132 	kfree(tree);
133 	return NULL;
134 }
135 
136 /* Release resources used by a btree */
hfs_btree_close(struct hfs_btree * tree)137 void hfs_btree_close(struct hfs_btree *tree)
138 {
139 	struct hfs_bnode *node;
140 	int i;
141 
142 	if (!tree)
143 		return;
144 
145 	for (i = 0; i < NODE_HASH_SIZE; i++) {
146 		while ((node = tree->node_hash[i])) {
147 			tree->node_hash[i] = node->next_hash;
148 			if (atomic_read(&node->refcnt))
149 				pr_err("node %d:%d still has %d user(s)!\n",
150 				       node->tree->cnid, node->this,
151 				       atomic_read(&node->refcnt));
152 			hfs_bnode_free(node);
153 			tree->node_hash_cnt--;
154 		}
155 	}
156 	iput(tree->inode);
157 	kfree(tree);
158 }
159 
hfs_btree_write(struct hfs_btree * tree)160 void hfs_btree_write(struct hfs_btree *tree)
161 {
162 	struct hfs_btree_header_rec *head;
163 	struct hfs_bnode *node;
164 	struct page *page;
165 
166 	node = hfs_bnode_find(tree, 0);
167 	if (IS_ERR(node))
168 		/* panic? */
169 		return;
170 	/* Load the header */
171 	page = node->page[0];
172 	head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
173 
174 	head->root = cpu_to_be32(tree->root);
175 	head->leaf_count = cpu_to_be32(tree->leaf_count);
176 	head->leaf_head = cpu_to_be32(tree->leaf_head);
177 	head->leaf_tail = cpu_to_be32(tree->leaf_tail);
178 	head->node_count = cpu_to_be32(tree->node_count);
179 	head->free_nodes = cpu_to_be32(tree->free_nodes);
180 	head->attributes = cpu_to_be32(tree->attributes);
181 	head->depth = cpu_to_be16(tree->depth);
182 
183 	kunmap(page);
184 	set_page_dirty(page);
185 	hfs_bnode_put(node);
186 }
187 
hfs_bmap_new_bmap(struct hfs_bnode * prev,u32 idx)188 static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
189 {
190 	struct hfs_btree *tree = prev->tree;
191 	struct hfs_bnode *node;
192 	struct hfs_bnode_desc desc;
193 	__be32 cnid;
194 
195 	node = hfs_bnode_create(tree, idx);
196 	if (IS_ERR(node))
197 		return node;
198 
199 	if (!tree->free_nodes)
200 		panic("FIXME!!!");
201 	tree->free_nodes--;
202 	prev->next = idx;
203 	cnid = cpu_to_be32(idx);
204 	hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
205 
206 	node->type = HFS_NODE_MAP;
207 	node->num_recs = 1;
208 	hfs_bnode_clear(node, 0, tree->node_size);
209 	desc.next = 0;
210 	desc.prev = 0;
211 	desc.type = HFS_NODE_MAP;
212 	desc.height = 0;
213 	desc.num_recs = cpu_to_be16(1);
214 	desc.reserved = 0;
215 	hfs_bnode_write(node, &desc, 0, sizeof(desc));
216 	hfs_bnode_write_u16(node, 14, 0x8000);
217 	hfs_bnode_write_u16(node, tree->node_size - 2, 14);
218 	hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
219 
220 	return node;
221 }
222 
223 /* Make sure @tree has enough space for the @rsvd_nodes */
hfs_bmap_reserve(struct hfs_btree * tree,int rsvd_nodes)224 int hfs_bmap_reserve(struct hfs_btree *tree, int rsvd_nodes)
225 {
226 	struct inode *inode = tree->inode;
227 	u32 count;
228 	int res;
229 
230 	while (tree->free_nodes < rsvd_nodes) {
231 		res = hfs_extend_file(inode);
232 		if (res)
233 			return res;
234 		HFS_I(inode)->phys_size = inode->i_size =
235 				(loff_t)HFS_I(inode)->alloc_blocks *
236 				HFS_SB(tree->sb)->alloc_blksz;
237 		HFS_I(inode)->fs_blocks = inode->i_size >>
238 					  tree->sb->s_blocksize_bits;
239 		inode_set_bytes(inode, inode->i_size);
240 		count = inode->i_size >> tree->node_size_shift;
241 		tree->free_nodes += count - tree->node_count;
242 		tree->node_count = count;
243 	}
244 	return 0;
245 }
246 
hfs_bmap_alloc(struct hfs_btree * tree)247 struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
248 {
249 	struct hfs_bnode *node, *next_node;
250 	struct page **pagep;
251 	u32 nidx, idx;
252 	unsigned off;
253 	u16 off16;
254 	u16 len;
255 	u8 *data, byte, m;
256 	int i, res;
257 
258 	res = hfs_bmap_reserve(tree, 1);
259 	if (res)
260 		return ERR_PTR(res);
261 
262 	nidx = 0;
263 	node = hfs_bnode_find(tree, nidx);
264 	if (IS_ERR(node))
265 		return node;
266 	len = hfs_brec_lenoff(node, 2, &off16);
267 	off = off16;
268 
269 	off += node->page_offset;
270 	pagep = node->page + (off >> PAGE_SHIFT);
271 	data = kmap(*pagep);
272 	off &= ~PAGE_MASK;
273 	idx = 0;
274 
275 	for (;;) {
276 		while (len) {
277 			byte = data[off];
278 			if (byte != 0xff) {
279 				for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
280 					if (!(byte & m)) {
281 						idx += i;
282 						data[off] |= m;
283 						set_page_dirty(*pagep);
284 						kunmap(*pagep);
285 						tree->free_nodes--;
286 						mark_inode_dirty(tree->inode);
287 						hfs_bnode_put(node);
288 						return hfs_bnode_create(tree, idx);
289 					}
290 				}
291 			}
292 			if (++off >= PAGE_SIZE) {
293 				kunmap(*pagep);
294 				data = kmap(*++pagep);
295 				off = 0;
296 			}
297 			idx += 8;
298 			len--;
299 		}
300 		kunmap(*pagep);
301 		nidx = node->next;
302 		if (!nidx) {
303 			printk(KERN_DEBUG "create new bmap node...\n");
304 			next_node = hfs_bmap_new_bmap(node, idx);
305 		} else
306 			next_node = hfs_bnode_find(tree, nidx);
307 		hfs_bnode_put(node);
308 		if (IS_ERR(next_node))
309 			return next_node;
310 		node = next_node;
311 
312 		len = hfs_brec_lenoff(node, 0, &off16);
313 		off = off16;
314 		off += node->page_offset;
315 		pagep = node->page + (off >> PAGE_SHIFT);
316 		data = kmap(*pagep);
317 		off &= ~PAGE_MASK;
318 	}
319 }
320 
hfs_bmap_free(struct hfs_bnode * node)321 void hfs_bmap_free(struct hfs_bnode *node)
322 {
323 	struct hfs_btree *tree;
324 	struct page *page;
325 	u16 off, len;
326 	u32 nidx;
327 	u8 *data, byte, m;
328 
329 	hfs_dbg(BNODE_MOD, "btree_free_node: %u\n", node->this);
330 	tree = node->tree;
331 	nidx = node->this;
332 	node = hfs_bnode_find(tree, 0);
333 	if (IS_ERR(node))
334 		return;
335 	len = hfs_brec_lenoff(node, 2, &off);
336 	while (nidx >= len * 8) {
337 		u32 i;
338 
339 		nidx -= len * 8;
340 		i = node->next;
341 		if (!i) {
342 			/* panic */;
343 			pr_crit("unable to free bnode %u. bmap not found!\n",
344 				node->this);
345 			hfs_bnode_put(node);
346 			return;
347 		}
348 		hfs_bnode_put(node);
349 		node = hfs_bnode_find(tree, i);
350 		if (IS_ERR(node))
351 			return;
352 		if (node->type != HFS_NODE_MAP) {
353 			/* panic */;
354 			pr_crit("invalid bmap found! (%u,%d)\n",
355 				node->this, node->type);
356 			hfs_bnode_put(node);
357 			return;
358 		}
359 		len = hfs_brec_lenoff(node, 0, &off);
360 	}
361 	off += node->page_offset + nidx / 8;
362 	page = node->page[off >> PAGE_SHIFT];
363 	data = kmap(page);
364 	off &= ~PAGE_MASK;
365 	m = 1 << (~nidx & 7);
366 	byte = data[off];
367 	if (!(byte & m)) {
368 		pr_crit("trying to free free bnode %u(%d)\n",
369 			node->this, node->type);
370 		kunmap(page);
371 		hfs_bnode_put(node);
372 		return;
373 	}
374 	data[off] = byte & ~m;
375 	set_page_dirty(page);
376 	kunmap(page);
377 	hfs_bnode_put(node);
378 	tree->free_nodes++;
379 	mark_inode_dirty(tree->inode);
380 }
381