fs/hfsplus/bfind.c

   1 /*
   2  *  linux/fs/hfsplus/bfind.c
   3  *
   4  * Copyright (C) 2001
   5  * Brad Boyer (flar@allandria.com)
   6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   7  *
   8  * Search routines for btrees
   9  */
  10
  11 #include <linux/slab.h>
  12 #include "hfsplus_fs.h"
  13
  14 int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
  15 {
  16         void *ptr;
  17
  18         fd->tree = tree;
  19         fd->bnode = NULL;
  20         ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
  21         if (!ptr)
  22                 return -ENOMEM;
  23         fd->search_key = ptr;
  24         fd->key = ptr + tree->max_key_len + 2;
  25         dprint(DBG_BNODE_REFS, "find_init: %d (%p)\n",
  26                 tree->cnid, __builtin_return_address(0));
  27         switch (tree->cnid) {
  28         case HFSPLUS_CAT_CNID:
  29                 mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
  30                 break;
  31         case HFSPLUS_EXT_CNID:
  32                 mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
  33                 break;
  34         case HFSPLUS_ATTR_CNID:
  35                 mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
  36                 break;
  37         default:
  38                 BUG();
  39         }
  40         return 0;
  41 }
  42
  43 void hfs_find_exit(struct hfs_find_data *fd)
  44 {
  45         hfs_bnode_put(fd->bnode);
  46         kfree(fd->search_key);
  47         dprint(DBG_BNODE_REFS, "find_exit: %d (%p)\n",
  48                 fd->tree->cnid, __builtin_return_address(0));
  49         mutex_unlock(&fd->tree->tree_lock);
  50         fd->tree = NULL;
  51 }
  52
  53 int hfs_find_1st_rec_by_cnid(struct hfs_bnode *bnode,
  54                                 struct hfs_find_data *fd,
  55                                 int *begin,
  56                                 int *end,
  57                                 int *cur_rec)
  58 {
  59         __be32 cur_cnid, search_cnid;
  60
  61         if (bnode->tree->cnid == HFSPLUS_EXT_CNID) {
  62                 cur_cnid = fd->key->ext.cnid;
  63                 search_cnid = fd->search_key->ext.cnid;
  64         } else if (bnode->tree->cnid == HFSPLUS_CAT_CNID) {
  65                 cur_cnid = fd->key->cat.parent;
  66                 search_cnid = fd->search_key->cat.parent;
  67         } else if (bnode->tree->cnid == HFSPLUS_ATTR_CNID) {
  68                 cur_cnid = fd->key->attr.cnid;
  69                 search_cnid = fd->search_key->attr.cnid;
  70         } else
  71                 BUG();
  72
  73         if (cur_cnid == search_cnid) {
  74                 (*end) = (*cur_rec);
  75                 if ((*begin) == (*end))
  76                         return 1;
  77         } else {
  78                 if (be32_to_cpu(cur_cnid) < be32_to_cpu(search_cnid))
  79                         (*begin) = (*cur_rec) + 1;
  80                 else
  81                         (*end) = (*cur_rec) - 1;
  82         }
  83
  84         return 0;
  85 }
  86
  87 int hfs_find_rec_by_key(struct hfs_bnode *bnode,
  88                                 struct hfs_find_data *fd,
  89                                 int *begin,
  90                                 int *end,
  91                                 int *cur_rec)
  92 {
  93         int cmpval;
  94
  95         cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  96         if (!cmpval) {
  97                 (*end) = (*cur_rec);
  98                 return 1;
  99         }
 100         if (cmpval < 0)
 101                 (*begin) = (*cur_rec) + 1;
 102         else
 103                 *(end) = (*cur_rec) - 1;
 104
 105         return 0;
 106 }
 107
 108 /* Find the record in bnode that best matches key (not greater than...)*/
 109 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd,
 110                                         search_strategy_t rec_found)
 111 {
 112         u16 off, len, keylen;
 113         int rec;
 114         int b, e;
 115         int res;
 116
 117         if (!rec_found)
 118                 BUG();
 119
 120         b = 0;
 121         e = bnode->num_recs - 1;
 122         res = -ENOENT;
 123         do {
 124                 rec = (e + b) / 2;
 125                 len = hfs_brec_lenoff(bnode, rec, &off);
 126                 keylen = hfs_brec_keylen(bnode, rec);
 127                 if (keylen == 0) {
 128                         res = -EINVAL;
 129                         goto fail;
 130                 }
 131                 hfs_bnode_read(bnode, fd->key, off, keylen);
 132                 if (rec_found(bnode, fd, &b, &e, &rec)) {
 133                         res = 0;
 134                         goto done;
 135                 }
 136         } while (b <= e);
 137
 138         if (rec != e && e >= 0) {
 139                 len = hfs_brec_lenoff(bnode, e, &off);
 140                 keylen = hfs_brec_keylen(bnode, e);
 141                 if (keylen == 0) {
 142                         res = -EINVAL;
 143                         goto fail;
 144                 }
 145                 hfs_bnode_read(bnode, fd->key, off, keylen);
 146         }
 147
 148 done:
 149         fd->record = e;
 150         fd->keyoffset = off;
 151         fd->keylength = keylen;
 152         fd->entryoffset = off + keylen;
 153         fd->entrylength = len - keylen;
 154
 155 fail:
 156         return res;
 157 }
 158
 159 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 160 /* Return allocated copy of node found, set recnum to best record */
 161 int hfs_brec_find(struct hfs_find_data *fd, search_strategy_t do_key_compare)
 162 {
 163         struct hfs_btree *tree;
 164         struct hfs_bnode *bnode;
 165         u32 nidx, parent;
 166         __be32 data;
 167         int height, res;
 168
 169         tree = fd->tree;
 170         if (fd->bnode)
 171                 hfs_bnode_put(fd->bnode);
 172         fd->bnode = NULL;
 173         nidx = tree->root;
 174         if (!nidx)
 175                 return -ENOENT;
 176         height = tree->depth;
 177         res = 0;
 178         parent = 0;
 179         for (;;) {
 180                 bnode = hfs_bnode_find(tree, nidx);
 181                 if (IS_ERR(bnode)) {
 182                         res = PTR_ERR(bnode);
 183                         bnode = NULL;
 184                         break;
 185                 }
 186                 if (bnode->height != height)
 187                         goto invalid;
 188                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 189                         goto invalid;
 190                 bnode->parent = parent;
 191
 192                 res = __hfs_brec_find(bnode, fd, do_key_compare);
 193                 if (!height)
 194                         break;
 195                 if (fd->record < 0)
 196                         goto release;
 197
 198                 parent = nidx;
 199                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 200                 nidx = be32_to_cpu(data);
 201                 hfs_bnode_put(bnode);
 202         }
 203         fd->bnode = bnode;
 204         return res;
 205
 206 invalid:
 207         printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 208                 height, bnode->height, bnode->type, nidx, parent);
 209         res = -EIO;
 210 release:
 211         hfs_bnode_put(bnode);
 212         return res;
 213 }
 214
 215 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 216 {
 217         int res;
 218
 219         res = hfs_brec_find(fd, hfs_find_rec_by_key);
 220         if (res)
 221                 return res;
 222         if (fd->entrylength > rec_len)
 223                 return -EINVAL;
 224         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 225         return 0;
 226 }
 227
 228 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 229 {
 230         struct hfs_btree *tree;
 231         struct hfs_bnode *bnode;
 232         int idx, res = 0;
 233         u16 off, len, keylen;
 234
 235         bnode = fd->bnode;
 236         tree = bnode->tree;
 237
 238         if (cnt < 0) {
 239                 cnt = -cnt;
 240                 while (cnt > fd->record) {
 241                         cnt -= fd->record + 1;
 242                         fd->record = bnode->num_recs - 1;
 243                         idx = bnode->prev;
 244                         if (!idx) {
 245                                 res = -ENOENT;
 246                                 goto out;
 247                         }
 248                         hfs_bnode_put(bnode);
 249                         bnode = hfs_bnode_find(tree, idx);
 250                         if (IS_ERR(bnode)) {
 251                                 res = PTR_ERR(bnode);
 252                                 bnode = NULL;
 253                                 goto out;
 254                         }
 255                 }
 256                 fd->record -= cnt;
 257         } else {
 258                 while (cnt >= bnode->num_recs - fd->record) {
 259                         cnt -= bnode->num_recs - fd->record;
 260                         fd->record = 0;
 261                         idx = bnode->next;
 262                         if (!idx) {
 263                                 res = -ENOENT;
 264                                 goto out;
 265                         }
 266                         hfs_bnode_put(bnode);
 267                         bnode = hfs_bnode_find(tree, idx);
 268                         if (IS_ERR(bnode)) {
 269                                 res = PTR_ERR(bnode);
 270                                 bnode = NULL;
 271                                 goto out;
 272                         }
 273                 }
 274                 fd->record += cnt;
 275         }
 276
 277         len = hfs_brec_lenoff(bnode, fd->record, &off);
 278         keylen = hfs_brec_keylen(bnode, fd->record);
 279         if (keylen == 0) {
 280                 res = -EINVAL;
 281                 goto out;
 282         }
 283         fd->keyoffset = off;
 284         fd->keylength = keylen;
 285         fd->entryoffset = off + keylen;
 286         fd->entrylength = len - keylen;
 287         hfs_bnode_read(bnode, fd->key, off, keylen);
 288 out:
 289         fd->bnode = bnode;
 290         return res;
 291 }