fs/hfsplus/btree.c

   1 /*
   2  *  linux/fs/hfsplus/btree.c
   3  *
   4  * Copyright (C) 2001
   5  * Brad Boyer (flar@allandria.com)
   6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   7  *
   8  * Handle opening/closing btree
   9  */
  10
  11 #include <linux/slab.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/log2.h>
  14
  15 #include "hfsplus_fs.h"
  16 #include "hfsplus_raw.h"
  17
  18
  19 /* Get a reference to a B*Tree and do some initial checks */
  20 struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
  21 {
  22         struct hfs_btree *tree;
  23         struct hfs_btree_header_rec *head;
  24         struct address_space *mapping;
  25         struct inode *inode;
  26         struct page *page;
  27         unsigned int size;
  28
  29         tree = kzalloc(sizeof(*tree), GFP_KERNEL);
  30         if (!tree)
  31                 return NULL;
  32
  33         init_MUTEX(&tree->tree_lock);
  34         spin_lock_init(&tree->hash_lock);
  35         tree->sb = sb;
  36         tree->cnid = id;
  37         inode = hfsplus_iget(sb, id);
  38         if (IS_ERR(inode))
  39                 goto free_tree;
  40         tree->inode = inode;
  41
  42         mapping = tree->inode->i_mapping;
  43         page = read_mapping_page(mapping, 0, NULL);
  44         if (IS_ERR(page))
  45                 goto free_tree;
  46
  47         /* Load the header */
  48         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
  49         tree->root = be32_to_cpu(head->root);
  50         tree->leaf_count = be32_to_cpu(head->leaf_count);
  51         tree->leaf_head = be32_to_cpu(head->leaf_head);
  52         tree->leaf_tail = be32_to_cpu(head->leaf_tail);
  53         tree->node_count = be32_to_cpu(head->node_count);
  54         tree->free_nodes = be32_to_cpu(head->free_nodes);
  55         tree->attributes = be32_to_cpu(head->attributes);
  56         tree->node_size = be16_to_cpu(head->node_size);
  57         tree->max_key_len = be16_to_cpu(head->max_key_len);
  58         tree->depth = be16_to_cpu(head->depth);
  59
  60         /* Set the correct compare function */
  61         if (id == HFSPLUS_EXT_CNID) {
  62                 tree->keycmp = hfsplus_ext_cmp_key;
  63         } else if (id == HFSPLUS_CAT_CNID) {
  64                 if ((HFSPLUS_SB(sb).flags & HFSPLUS_SB_HFSX) &&
  65                     (head->key_type == HFSPLUS_KEY_BINARY))
  66                         tree->keycmp = hfsplus_cat_bin_cmp_key;
  67                 else {
  68                         tree->keycmp = hfsplus_cat_case_cmp_key;
  69                         HFSPLUS_SB(sb).flags |= HFSPLUS_SB_CASEFOLD;
  70                 }
  71         } else {
  72                 printk(KERN_ERR "hfs: unknown B*Tree requested\n");
  73                 goto fail_page;
  74         }
  75
  76         size = tree->node_size;
  77         if (!is_power_of_2(size))
  78                 goto fail_page;
  79         if (!tree->node_count)
  80                 goto fail_page;
  81         tree->node_size_shift = ffs(size) - 1;
  82
  83         tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  84
  85         kunmap(page);
  86         page_cache_release(page);
  87         return tree;
  88
  89  fail_page:
  90         tree->inode->i_mapping->a_ops = &hfsplus_aops;
  91         page_cache_release(page);
  92  free_tree:
  93         iput(tree->inode);
  94         kfree(tree);
  95         return NULL;
  96 }
  97
  98 /* Release resources used by a btree */
  99 void hfs_btree_close(struct hfs_btree *tree)
 100 {
 101         struct hfs_bnode *node;
 102         int i;
 103
 104         if (!tree)
 105                 return;
 106
 107         for (i = 0; i < NODE_HASH_SIZE; i++) {
 108                 while ((node = tree->node_hash[i])) {
 109                         tree->node_hash[i] = node->next_hash;
 110                         if (atomic_read(&node->refcnt))
 111                                 printk(KERN_CRIT "hfs: node %d:%d still has %d user(s)!\n",
 112                                         node->tree->cnid, node->this, atomic_read(&node->refcnt));
 113                         hfs_bnode_free(node);
 114                         tree->node_hash_cnt--;
 115                 }
 116         }
 117         iput(tree->inode);
 118         kfree(tree);
 119 }
 120
 121 void hfs_btree_write(struct hfs_btree *tree)
 122 {
 123         struct hfs_btree_header_rec *head;
 124         struct hfs_bnode *node;
 125         struct page *page;
 126
 127         node = hfs_bnode_find(tree, 0);
 128         if (IS_ERR(node))
 129                 /* panic? */
 130                 return;
 131         /* Load the header */
 132         page = node->page[0];
 133         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
 134
 135         head->root = cpu_to_be32(tree->root);
 136         head->leaf_count = cpu_to_be32(tree->leaf_count);
 137         head->leaf_head = cpu_to_be32(tree->leaf_head);
 138         head->leaf_tail = cpu_to_be32(tree->leaf_tail);
 139         head->node_count = cpu_to_be32(tree->node_count);
 140         head->free_nodes = cpu_to_be32(tree->free_nodes);
 141         head->attributes = cpu_to_be32(tree->attributes);
 142         head->depth = cpu_to_be16(tree->depth);
 143
 144         kunmap(page);
 145         set_page_dirty(page);
 146         hfs_bnode_put(node);
 147 }
 148
 149 static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
 150 {
 151         struct hfs_btree *tree = prev->tree;
 152         struct hfs_bnode *node;
 153         struct hfs_bnode_desc desc;
 154         __be32 cnid;
 155
 156         node = hfs_bnode_create(tree, idx);
 157         if (IS_ERR(node))
 158                 return node;
 159
 160         tree->free_nodes--;
 161         prev->next = idx;
 162         cnid = cpu_to_be32(idx);
 163         hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
 164
 165         node->type = HFS_NODE_MAP;
 166         node->num_recs = 1;
 167         hfs_bnode_clear(node, 0, tree->node_size);
 168         desc.next = 0;
 169         desc.prev = 0;
 170         desc.type = HFS_NODE_MAP;
 171         desc.height = 0;
 172         desc.num_recs = cpu_to_be16(1);
 173         desc.reserved = 0;
 174         hfs_bnode_write(node, &desc, 0, sizeof(desc));
 175         hfs_bnode_write_u16(node, 14, 0x8000);
 176         hfs_bnode_write_u16(node, tree->node_size - 2, 14);
 177         hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
 178
 179         return node;
 180 }
 181
 182 struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
 183 {
 184         struct hfs_bnode *node, *next_node;
 185         struct page **pagep;
 186         u32 nidx, idx;
 187         unsigned off;
 188         u16 off16;
 189         u16 len;
 190         u8 *data, byte, m;
 191         int i;
 192
 193         while (!tree->free_nodes) {
 194                 struct inode *inode = tree->inode;
 195                 u32 count;
 196                 int res;
 197
 198                 res = hfsplus_file_extend(inode);
 199                 if (res)
 200                         return ERR_PTR(res);
 201                 HFSPLUS_I(inode).phys_size = inode->i_size =
 202                                 (loff_t)HFSPLUS_I(inode).alloc_blocks <<
 203                                 HFSPLUS_SB(tree->sb).alloc_blksz_shift;
 204                 HFSPLUS_I(inode).fs_blocks = HFSPLUS_I(inode).alloc_blocks <<
 205                                              HFSPLUS_SB(tree->sb).fs_shift;
 206                 inode_set_bytes(inode, inode->i_size);
 207                 count = inode->i_size >> tree->node_size_shift;
 208                 tree->free_nodes = count - tree->node_count;
 209                 tree->node_count = count;
 210         }
 211
 212         nidx = 0;
 213         node = hfs_bnode_find(tree, nidx);
 214         if (IS_ERR(node))
 215                 return node;
 216         len = hfs_brec_lenoff(node, 2, &off16);
 217         off = off16;
 218
 219         off += node->page_offset;
 220         pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 221         data = kmap(*pagep);
 222         off &= ~PAGE_CACHE_MASK;
 223         idx = 0;
 224
 225         for (;;) {
 226                 while (len) {
 227                         byte = data[off];
 228                         if (byte != 0xff) {
 229                                 for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
 230                                         if (!(byte & m)) {
 231                                                 idx += i;
 232                                                 data[off] |= m;
 233                                                 set_page_dirty(*pagep);
 234                                                 kunmap(*pagep);
 235                                                 tree->free_nodes--;
 236                                                 mark_inode_dirty(tree->inode);
 237                                                 hfs_bnode_put(node);
 238                                                 return hfs_bnode_create(tree, idx);
 239                                         }
 240                                 }
 241                         }
 242                         if (++off >= PAGE_CACHE_SIZE) {
 243                                 kunmap(*pagep);
 244                                 data = kmap(*++pagep);
 245                                 off = 0;
 246                         }
 247                         idx += 8;
 248                         len--;
 249                 }
 250                 kunmap(*pagep);
 251                 nidx = node->next;
 252                 if (!nidx) {
 253                         printk(KERN_DEBUG "hfs: create new bmap node...\n");
 254                         next_node = hfs_bmap_new_bmap(node, idx);
 255                 } else
 256                         next_node = hfs_bnode_find(tree, nidx);
 257                 hfs_bnode_put(node);
 258                 if (IS_ERR(next_node))
 259                         return next_node;
 260                 node = next_node;
 261
 262                 len = hfs_brec_lenoff(node, 0, &off16);
 263                 off = off16;
 264                 off += node->page_offset;
 265                 pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 266                 data = kmap(*pagep);
 267                 off &= ~PAGE_CACHE_MASK;
 268         }
 269 }
 270
 271 void hfs_bmap_free(struct hfs_bnode *node)
 272 {
 273         struct hfs_btree *tree;
 274         struct page *page;
 275         u16 off, len;
 276         u32 nidx;
 277         u8 *data, byte, m;
 278
 279         dprint(DBG_BNODE_MOD, "btree_free_node: %u\n", node->this);
 280         BUG_ON(!node->this);
 281         tree = node->tree;
 282         nidx = node->this;
 283         node = hfs_bnode_find(tree, 0);
 284         if (IS_ERR(node))
 285                 return;
 286         len = hfs_brec_lenoff(node, 2, &off);
 287         while (nidx >= len * 8) {
 288                 u32 i;
 289
 290                 nidx -= len * 8;
 291                 i = node->next;
 292                 hfs_bnode_put(node);
 293                 if (!i) {
 294                         /* panic */;
 295                         printk(KERN_CRIT "hfs: unable to free bnode %u. bmap not found!\n", node->this);
 296                         return;
 297                 }
 298                 node = hfs_bnode_find(tree, i);
 299                 if (IS_ERR(node))
 300                         return;
 301                 if (node->type != HFS_NODE_MAP) {
 302                         /* panic */;
 303                         printk(KERN_CRIT "hfs: invalid bmap found! (%u,%d)\n", node->this, node->type);
 304                         hfs_bnode_put(node);
 305                         return;
 306                 }
 307                 len = hfs_brec_lenoff(node, 0, &off);
 308         }
 309         off += node->page_offset + nidx / 8;
 310         page = node->page[off >> PAGE_CACHE_SHIFT];
 311         data = kmap(page);
 312         off &= ~PAGE_CACHE_MASK;
 313         m = 1 << (~nidx & 7);
 314         byte = data[off];
 315         if (!(byte & m)) {
 316                 printk(KERN_CRIT "hfs: trying to free free bnode %u(%d)\n", node->this, node->type);
 317                 kunmap(page);
 318                 hfs_bnode_put(node);
 319                 return;
 320         }
 321         data[off] = byte & ~m;
 322         set_page_dirty(page);
 323         kunmap(page);
 324         hfs_bnode_put(node);
 325         tree->free_nodes++;
 326         mark_inode_dirty(tree->inode);
 327 }