btree.c

  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 */
 19struct 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 folio *folio;
 25	struct buffer_head *bh;
 26	unsigned int size;
 27	u16 dblock;
 28	sector_t start_block;
 29	loff_t offset;
 30
 31	tree = kzalloc(sizeof(*tree), GFP_KERNEL);
 32	if (!tree)
 33		return NULL;
 34
 35	mutex_init(&tree->tree_lock);
 36	spin_lock_init(&tree->hash_lock);
 37	/* Set the correct compare function */
 38	tree->sb = sb;
 39	tree->cnid = id;
 40	tree->keycmp = keycmp;
 41
 42	tree->inode = iget_locked(sb, id);
 43	if (!tree->inode)
 44		goto free_tree;
 45	BUG_ON(!(inode_state_read_once(tree->inode) & I_NEW));
 46	{
 47	struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
 48	HFS_I(tree->inode)->flags = 0;
 49	mutex_init(&HFS_I(tree->inode)->extents_lock);
 50	switch (id) {
 51	case HFS_EXT_CNID:
 52		hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
 53				    mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
 54		if (HFS_I(tree->inode)->alloc_blocks >
 55					HFS_I(tree->inode)->first_blocks) {
 56			pr_err("invalid btree extent records\n");
 57			unlock_new_inode(tree->inode);
 58			goto free_inode;
 59		}
 60
 61		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
 62		break;
 63	case HFS_CAT_CNID:
 64		hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
 65				    mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
 66
 67		if (!HFS_I(tree->inode)->first_blocks) {
 68			pr_err("invalid btree extent records (0 size)\n");
 69			unlock_new_inode(tree->inode);
 70			goto free_inode;
 71		}
 72
 73		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
 74		break;
 75	default:
 76		BUG();
 77	}
 78	}
 79	unlock_new_inode(tree->inode);
 80
 81	mapping = tree->inode->i_mapping;
 82	folio = filemap_grab_folio(mapping, 0);
 83	if (IS_ERR(folio))
 84		goto free_inode;
 85
 86	folio_zero_range(folio, 0, folio_size(folio));
 87
 88	dblock = hfs_ext_find_block(HFS_I(tree->inode)->first_extents, 0);
 89	start_block = HFS_SB(sb)->fs_start + (dblock * HFS_SB(sb)->fs_div);
 90
 91	size = folio_size(folio);
 92	offset = 0;
 93	while (size > 0) {
 94		size_t len;
 95
 96		bh = sb_bread(sb, start_block);
 97		if (!bh) {
 98			pr_err("unable to read tree header\n");
 99			goto put_folio;
100		}
101
102		len = min_t(size_t, folio_size(folio), sb->s_blocksize);
103		memcpy_to_folio(folio, offset, bh->b_data, sb->s_blocksize);
104
105		brelse(bh);
106
107		start_block++;
108		offset += len;
109		size -= len;
110	}
111
112	folio_mark_uptodate(folio);
113
114	/* Load the header */
115	head = (struct hfs_btree_header_rec *)(kmap_local_folio(folio, 0) +
116					       sizeof(struct hfs_bnode_desc));
117	tree->root = be32_to_cpu(head->root);
118	tree->leaf_count = be32_to_cpu(head->leaf_count);
119	tree->leaf_head = be32_to_cpu(head->leaf_head);
120	tree->leaf_tail = be32_to_cpu(head->leaf_tail);
121	tree->node_count = be32_to_cpu(head->node_count);
122	tree->free_nodes = be32_to_cpu(head->free_nodes);
123	tree->attributes = be32_to_cpu(head->attributes);
124	tree->node_size = be16_to_cpu(head->node_size);
125	tree->max_key_len = be16_to_cpu(head->max_key_len);
126	tree->depth = be16_to_cpu(head->depth);
127
128	size = tree->node_size;
129	if (!is_power_of_2(size))
130		goto fail_folio;
131	if (!tree->node_count)
132		goto fail_folio;
133	switch (id) {
134	case HFS_EXT_CNID:
135		if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
136			pr_err("invalid extent max_key_len %d\n",
137			       tree->max_key_len);
138			goto fail_folio;
139		}
140		break;
141	case HFS_CAT_CNID:
142		if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
143			pr_err("invalid catalog max_key_len %d\n",
144			       tree->max_key_len);
145			goto fail_folio;
146		}
147		break;
148	default:
149		BUG();
150	}
151
152	tree->node_size_shift = ffs(size) - 1;
153	tree->pages_per_bnode = (tree->node_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
154
155	kunmap_local(head);
156	folio_unlock(folio);
157	folio_put(folio);
158	return tree;
159
160fail_folio:
161	kunmap_local(head);
162put_folio:
163	folio_unlock(folio);
164	folio_put(folio);
165free_inode:
166	tree->inode->i_mapping->a_ops = &hfs_aops;
167	iput(tree->inode);
168free_tree:
169	kfree(tree);
170	return NULL;
171}
172
173/* Release resources used by a btree */
174void hfs_btree_close(struct hfs_btree *tree)
175{
176	struct hfs_bnode *node;
177	int i;
178
179	if (!tree)
180		return;
181
182	for (i = 0; i < NODE_HASH_SIZE; i++) {
183		while ((node = tree->node_hash[i])) {
184			tree->node_hash[i] = node->next_hash;
185			if (atomic_read(&node->refcnt))
186				pr_err("node %d:%d still has %d user(s)!\n",
187				       node->tree->cnid, node->this,
188				       atomic_read(&node->refcnt));
189			hfs_bnode_free(node);
190			tree->node_hash_cnt--;
191		}
192	}
193	iput(tree->inode);
194	kfree(tree);
195}
196
197void hfs_btree_write(struct hfs_btree *tree)
198{
199	struct hfs_btree_header_rec *head;
200	struct hfs_bnode *node;
201	struct page *page;
202
203	node = hfs_bnode_find(tree, 0);
204	if (IS_ERR(node))
205		/* panic? */
206		return;
207	/* Load the header */
208	page = node->page[0];
209	head = (struct hfs_btree_header_rec *)(kmap_local_page(page) +
210					       sizeof(struct hfs_bnode_desc));
211
212	head->root = cpu_to_be32(tree->root);
213	head->leaf_count = cpu_to_be32(tree->leaf_count);
214	head->leaf_head = cpu_to_be32(tree->leaf_head);
215	head->leaf_tail = cpu_to_be32(tree->leaf_tail);
216	head->node_count = cpu_to_be32(tree->node_count);
217	head->free_nodes = cpu_to_be32(tree->free_nodes);
218	head->attributes = cpu_to_be32(tree->attributes);
219	head->depth = cpu_to_be16(tree->depth);
220
221	kunmap_local(head);
222	set_page_dirty(page);
223	hfs_bnode_put(node);
224}
225
226static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
227{
228	struct hfs_btree *tree = prev->tree;
229	struct hfs_bnode *node;
230	struct hfs_bnode_desc desc;
231	__be32 cnid;
232
233	node = hfs_bnode_create(tree, idx);
234	if (IS_ERR(node))
235		return node;
236
237	if (!tree->free_nodes)
238		panic("FIXME!!!");
239	tree->free_nodes--;
240	prev->next = idx;
241	cnid = cpu_to_be32(idx);
242	hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
243
244	node->type = HFS_NODE_MAP;
245	node->num_recs = 1;
246	hfs_bnode_clear(node, 0, tree->node_size);
247	desc.next = 0;
248	desc.prev = 0;
249	desc.type = HFS_NODE_MAP;
250	desc.height = 0;
251	desc.num_recs = cpu_to_be16(1);
252	desc.reserved = 0;
253	hfs_bnode_write(node, &desc, 0, sizeof(desc));
254	hfs_bnode_write_u16(node, 14, 0x8000);
255	hfs_bnode_write_u16(node, tree->node_size - 2, 14);
256	hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
257
258	return node;
259}
260
261/* Make sure @tree has enough space for the @rsvd_nodes */
262int hfs_bmap_reserve(struct hfs_btree *tree, u32 rsvd_nodes)
263{
264	struct inode *inode = tree->inode;
265	u32 count;
266	int res;
267
268	while (tree->free_nodes < rsvd_nodes) {
269		res = hfs_extend_file(inode);
270		if (res)
271			return res;
272		HFS_I(inode)->phys_size = inode->i_size =
273				(loff_t)HFS_I(inode)->alloc_blocks *
274				HFS_SB(tree->sb)->alloc_blksz;
275		HFS_I(inode)->fs_blocks = inode->i_size >>
276					  tree->sb->s_blocksize_bits;
277		inode_set_bytes(inode, inode->i_size);
278		count = inode->i_size >> tree->node_size_shift;
279		tree->free_nodes += count - tree->node_count;
280		tree->node_count = count;
281	}
282	return 0;
283}
284
285struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
286{
287	struct hfs_bnode *node, *next_node;
288	struct page **pagep;
289	u32 nidx, idx;
290	unsigned off;
291	u16 off16;
292	u16 len;
293	u8 *data, byte, m;
294	int i, res;
295
296	res = hfs_bmap_reserve(tree, 1);
297	if (res)
298		return ERR_PTR(res);
299
300	nidx = 0;
301	node = hfs_bnode_find(tree, nidx);
302	if (IS_ERR(node))
303		return node;
304	len = hfs_brec_lenoff(node, 2, &off16);
305	off = off16;
306
307	off += node->page_offset;
308	pagep = node->page + (off >> PAGE_SHIFT);
309	data = kmap_local_page(*pagep);
310	off &= ~PAGE_MASK;
311	idx = 0;
312
313	for (;;) {
314		while (len) {
315			byte = data[off];
316			if (byte != 0xff) {
317				for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
318					if (!(byte & m)) {
319						idx += i;
320						data[off] |= m;
321						set_page_dirty(*pagep);
322						kunmap_local(data);
323						tree->free_nodes--;
324						mark_inode_dirty(tree->inode);
325						hfs_bnode_put(node);
326						return hfs_bnode_create(tree, idx);
327					}
328				}
329			}
330			if (++off >= PAGE_SIZE) {
331				kunmap_local(data);
332				data = kmap_local_page(*++pagep);
333				off = 0;
334			}
335			idx += 8;
336			len--;
337		}
338		kunmap_local(data);
339		nidx = node->next;
340		if (!nidx) {
341			printk(KERN_DEBUG "create new bmap node...\n");
342			next_node = hfs_bmap_new_bmap(node, idx);
343		} else
344			next_node = hfs_bnode_find(tree, nidx);
345		hfs_bnode_put(node);
346		if (IS_ERR(next_node))
347			return next_node;
348		node = next_node;
349
350		len = hfs_brec_lenoff(node, 0, &off16);
351		off = off16;
352		off += node->page_offset;
353		pagep = node->page + (off >> PAGE_SHIFT);
354		data = kmap_local_page(*pagep);
355		off &= ~PAGE_MASK;
356	}
357}
358
359void hfs_bmap_free(struct hfs_bnode *node)
360{
361	struct hfs_btree *tree;
362	struct page *page;
363	u16 off, len;
364	u32 nidx;
365	u8 *data, byte, m;
366
367	hfs_dbg("node %u\n", node->this);
368	tree = node->tree;
369	nidx = node->this;
370	node = hfs_bnode_find(tree, 0);
371	if (IS_ERR(node))
372		return;
373	len = hfs_brec_lenoff(node, 2, &off);
374	while (nidx >= len * 8) {
375		u32 i;
376
377		nidx -= len * 8;
378		i = node->next;
379		if (!i) {
380			/* panic */;
381			pr_crit("unable to free bnode %u. bmap not found!\n",
382				node->this);
383			hfs_bnode_put(node);
384			return;
385		}
386		hfs_bnode_put(node);
387		node = hfs_bnode_find(tree, i);
388		if (IS_ERR(node))
389			return;
390		if (node->type != HFS_NODE_MAP) {
391			/* panic */;
392			pr_crit("invalid bmap found! (%u,%d)\n",
393				node->this, node->type);
394			hfs_bnode_put(node);
395			return;
396		}
397		len = hfs_brec_lenoff(node, 0, &off);
398	}
399	off += node->page_offset + nidx / 8;
400	page = node->page[off >> PAGE_SHIFT];
401	data = kmap_local_page(page);
402	off &= ~PAGE_MASK;
403	m = 1 << (~nidx & 7);
404	byte = data[off];
405	if (!(byte & m)) {
406		pr_crit("trying to free free bnode %u(%d)\n",
407			node->this, node->type);
408		kunmap_local(data);
409		hfs_bnode_put(node);
410		return;
411	}
412	data[off] = byte & ~m;
413	set_page_dirty(page);
414	kunmap_local(data);
415	hfs_bnode_put(node);
416	tree->free_nodes++;
417	mark_inode_dirty(tree->inode);
418}