git.oblomov.eu Git - linux-2.6/blob - 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 page *page;
  26         unsigned int size;
  27
  28         tree = kzalloc(sizeof(*tree), GFP_KERNEL);
  29         if (!tree)
  30                 return NULL;
  31
  32         init_MUTEX(&tree->tree_lock);
  33         spin_lock_init(&tree->hash_lock);
  34         tree->sb = sb;
  35         tree->cnid = id;
  36         tree->inode = iget(sb, id);
  37         if (!tree->inode)
  38                 goto free_tree;
  39
  40         mapping = tree->inode->i_mapping;
  41         page = read_mapping_page(mapping, 0, NULL);
  42         if (IS_ERR(page))
  43                 goto free_tree;
  44
  45         /* Load the header */
  46         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
  47         tree->root = be32_to_cpu(head->root);
  48         tree->leaf_count = be32_to_cpu(head->leaf_count);
  49         tree->leaf_head = be32_to_cpu(head->leaf_head);
  50         tree->leaf_tail = be32_to_cpu(head->leaf_tail);
  51         tree->node_count = be32_to_cpu(head->node_count);
  52         tree->free_nodes = be32_to_cpu(head->free_nodes);
  53         tree->attributes = be32_to_cpu(head->attributes);
  54         tree->node_size = be16_to_cpu(head->node_size);
  55         tree->max_key_len = be16_to_cpu(head->max_key_len);
  56         tree->depth = be16_to_cpu(head->depth);
  57
  58         /* Set the correct compare function */
  59         if (id == HFSPLUS_EXT_CNID) {
  60                 tree->keycmp = hfsplus_ext_cmp_key;
  61         } else if (id == HFSPLUS_CAT_CNID) {
  62                 if ((HFSPLUS_SB(sb).flags & HFSPLUS_SB_HFSX) &&
  63                     (head->key_type == HFSPLUS_KEY_BINARY))
  64                         tree->keycmp = hfsplus_cat_bin_cmp_key;
  65                 else
  66                         tree->keycmp = hfsplus_cat_case_cmp_key;
  67         } else {
  68                 printk(KERN_ERR "hfs: unknown B*Tree requested\n");
  69                 goto fail_page;
  70         }
  71
  72         size = tree->node_size;
  73         if (!is_power_of_2(size))
  74                 goto fail_page;
  75         if (!tree->node_count)
  76                 goto fail_page;
  77         tree->node_size_shift = ffs(size) - 1;
  78
  79         tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  80
  81         kunmap(page);
  82         page_cache_release(page);
  83         return tree;
  84
  85  fail_page:
  86         tree->inode->i_mapping->a_ops = &hfsplus_aops;
  87         page_cache_release(page);
  88  free_tree:
  89         iput(tree->inode);
  90         kfree(tree);
  91         return NULL;
  92 }
  93
  94 /* Release resources used by a btree */
  95 void hfs_btree_close(struct hfs_btree *tree)
  96 {
  97         struct hfs_bnode *node;
  98         int i;
  99
 100         if (!tree)
 101                 return;
 102
 103         for (i = 0; i < NODE_HASH_SIZE; i++) {
 104                 while ((node = tree->node_hash[i])) {
 105                         tree->node_hash[i] = node->next_hash;
 106                         if (atomic_read(&node->refcnt))
 107                                 printk(KERN_CRIT "hfs: node %d:%d still has %d user(s)!\n",
 108                                         node->tree->cnid, node->this, atomic_read(&node->refcnt));
 109                         hfs_bnode_free(node);
 110                         tree->node_hash_cnt--;
 111                 }
 112         }
 113         iput(tree->inode);
 114         kfree(tree);
 115 }
 116
 117 void hfs_btree_write(struct hfs_btree *tree)
 118 {
 119         struct hfs_btree_header_rec *head;
 120         struct hfs_bnode *node;
 121         struct page *page;
 122
 123         node = hfs_bnode_find(tree, 0);
 124         if (IS_ERR(node))
 125                 /* panic? */
 126                 return;
 127         /* Load the header */
 128         page = node->page[0];
 129         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
 130
 131         head->root = cpu_to_be32(tree->root);
 132         head->leaf_count = cpu_to_be32(tree->leaf_count);
 133         head->leaf_head = cpu_to_be32(tree->leaf_head);
 134         head->leaf_tail = cpu_to_be32(tree->leaf_tail);
 135         head->node_count = cpu_to_be32(tree->node_count);
 136         head->free_nodes = cpu_to_be32(tree->free_nodes);
 137         head->attributes = cpu_to_be32(tree->attributes);
 138         head->depth = cpu_to_be16(tree->depth);
 139
 140         kunmap(page);
 141         set_page_dirty(page);
 142         hfs_bnode_put(node);
 143 }
 144
 145 static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
 146 {
 147         struct hfs_btree *tree = prev->tree;
 148         struct hfs_bnode *node;
 149         struct hfs_bnode_desc desc;
 150         __be32 cnid;
 151
 152         node = hfs_bnode_create(tree, idx);
 153         if (IS_ERR(node))
 154                 return node;
 155
 156         tree->free_nodes--;
 157         prev->next = idx;
 158         cnid = cpu_to_be32(idx);
 159         hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
 160
 161         node->type = HFS_NODE_MAP;
 162         node->num_recs = 1;
 163         hfs_bnode_clear(node, 0, tree->node_size);
 164         desc.next = 0;
 165         desc.prev = 0;
 166         desc.type = HFS_NODE_MAP;
 167         desc.height = 0;
 168         desc.num_recs = cpu_to_be16(1);
 169         desc.reserved = 0;
 170         hfs_bnode_write(node, &desc, 0, sizeof(desc));
 171         hfs_bnode_write_u16(node, 14, 0x8000);
 172         hfs_bnode_write_u16(node, tree->node_size - 2, 14);
 173         hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
 174
 175         return node;
 176 }
 177
 178 struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
 179 {
 180         struct hfs_bnode *node, *next_node;
 181         struct page **pagep;
 182         u32 nidx, idx;
 183         u16 off, len;
 184         u8 *data, byte, m;
 185         int i;
 186
 187         while (!tree->free_nodes) {
 188                 struct inode *inode = tree->inode;
 189                 u32 count;
 190                 int res;
 191
 192                 res = hfsplus_file_extend(inode);
 193                 if (res)
 194                         return ERR_PTR(res);
 195                 HFSPLUS_I(inode).phys_size = inode->i_size =
 196                                 (loff_t)HFSPLUS_I(inode).alloc_blocks <<
 197                                 HFSPLUS_SB(tree->sb).alloc_blksz_shift;
 198                 HFSPLUS_I(inode).fs_blocks = HFSPLUS_I(inode).alloc_blocks <<
 199                                              HFSPLUS_SB(tree->sb).fs_shift;
 200                 inode_set_bytes(inode, inode->i_size);
 201                 count = inode->i_size >> tree->node_size_shift;
 202                 tree->free_nodes = count - tree->node_count;
 203                 tree->node_count = count;
 204         }
 205
 206         nidx = 0;
 207         node = hfs_bnode_find(tree, nidx);
 208         if (IS_ERR(node))
 209                 return node;
 210         len = hfs_brec_lenoff(node, 2, &off);
 211
 212         off += node->page_offset;
 213         pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 214         data = kmap(*pagep);
 215         off &= ~PAGE_CACHE_MASK;
 216         idx = 0;
 217
 218         for (;;) {
 219                 while (len) {
 220                         byte = data[off];
 221                         if (byte != 0xff) {
 222                                 for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
 223                                         if (!(byte & m)) {
 224                                                 idx += i;
 225                                                 data[off] |= m;
 226                                                 set_page_dirty(*pagep);
 227                                                 kunmap(*pagep);
 228                                                 tree->free_nodes--;
 229                                                 mark_inode_dirty(tree->inode);
 230                                                 hfs_bnode_put(node);
 231                                                 return hfs_bnode_create(tree, idx);
 232                                         }
 233                                 }
 234                         }
 235                         if (++off >= PAGE_CACHE_SIZE) {
 236                                 kunmap(*pagep);
 237                                 data = kmap(*++pagep);
 238                                 off = 0;
 239                         }
 240                         idx += 8;
 241                         len--;
 242                 }
 243                 kunmap(*pagep);
 244                 nidx = node->next;
 245                 if (!nidx) {
 246                         printk(KERN_DEBUG "hfs: create new bmap node...\n");
 247                         next_node = hfs_bmap_new_bmap(node, idx);
 248                 } else
 249                         next_node = hfs_bnode_find(tree, nidx);
 250                 hfs_bnode_put(node);
 251                 if (IS_ERR(next_node))
 252                         return next_node;
 253                 node = next_node;
 254
 255                 len = hfs_brec_lenoff(node, 0, &off);
 256                 off += node->page_offset;
 257                 pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 258                 data = kmap(*pagep);
 259                 off &= ~PAGE_CACHE_MASK;
 260         }
 261 }
 262
 263 void hfs_bmap_free(struct hfs_bnode *node)
 264 {
 265         struct hfs_btree *tree;
 266         struct page *page;
 267         u16 off, len;
 268         u32 nidx;
 269         u8 *data, byte, m;
 270
 271         dprint(DBG_BNODE_MOD, "btree_free_node: %u\n", node->this);
 272         BUG_ON(!node->this);
 273         tree = node->tree;
 274         nidx = node->this;
 275         node = hfs_bnode_find(tree, 0);
 276         if (IS_ERR(node))
 277                 return;
 278         len = hfs_brec_lenoff(node, 2, &off);
 279         while (nidx >= len * 8) {
 280                 u32 i;
 281
 282                 nidx -= len * 8;
 283                 i = node->next;
 284                 hfs_bnode_put(node);
 285                 if (!i) {
 286                         /* panic */;
 287                         printk(KERN_CRIT "hfs: unable to free bnode %u. bmap not found!\n", node->this);
 288                         return;
 289                 }
 290                 node = hfs_bnode_find(tree, i);
 291                 if (IS_ERR(node))
 292                         return;
 293                 if (node->type != HFS_NODE_MAP) {
 294                         /* panic */;
 295                         printk(KERN_CRIT "hfs: invalid bmap found! (%u,%d)\n", node->this, node->type);
 296                         hfs_bnode_put(node);
 297                         return;
 298                 }
 299                 len = hfs_brec_lenoff(node, 0, &off);
 300         }
 301         off += node->page_offset + nidx / 8;
 302         page = node->page[off >> PAGE_CACHE_SHIFT];
 303         data = kmap(page);
 304         off &= ~PAGE_CACHE_MASK;
 305         m = 1 << (~nidx & 7);
 306         byte = data[off];
 307         if (!(byte & m)) {
 308                 printk(KERN_CRIT "hfs: trying to free free bnode %u(%d)\n", node->this, node->type);
 309                 kunmap(page);
 310                 hfs_bnode_put(node);
 311                 return;
 312         }
 313         data[off] = byte & ~m;
 314         set_page_dirty(page);
 315         kunmap(page);
 316         hfs_bnode_put(node);
 317         tree->free_nodes++;
 318         mark_inode_dirty(tree->inode);
 319 }