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Linux/fs/hfs/btree.c

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  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 */
 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 */
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 
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 
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 */
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 
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 
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 

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