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         hfs_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         hfs_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;
  60         __be32 search_cnid;
  61
  62         if (bnode->tree->cnid == HFSPLUS_EXT_CNID) {
  63                 cur_cnid = fd->key->ext.cnid;
  64                 search_cnid = fd->search_key->ext.cnid;
  65         } else if (bnode->tree->cnid == HFSPLUS_CAT_CNID) {
  66                 cur_cnid = fd->key->cat.parent;
  67                 search_cnid = fd->search_key->cat.parent;
  68         } else if (bnode->tree->cnid == HFSPLUS_ATTR_CNID) {
  69                 cur_cnid = fd->key->attr.cnid;
  70                 search_cnid = fd->search_key->attr.cnid;
  71         } else {
  72                 cur_cnid = 0;   /* used-uninitialized warning */
  73                 search_cnid = 0;
  74                 BUG();
  75         }
  76
  77         if (cur_cnid == search_cnid) {
  78                 (*end) = (*cur_rec);
  79                 if ((*begin) == (*end))
  80                         return 1;
  81         } else {
  82                 if (be32_to_cpu(cur_cnid) < be32_to_cpu(search_cnid))
  83                         (*begin) = (*cur_rec) + 1;
  84                 else
  85                         (*end) = (*cur_rec) - 1;
  86         }
  87
  88         return 0;
  89 }
  90
  91 int hfs_find_rec_by_key(struct hfs_bnode *bnode,
  92                                 struct hfs_find_data *fd,
  93                                 int *begin,
  94                                 int *end,
  95                                 int *cur_rec)
  96 {
  97         int cmpval;
  98
  99         cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
 100         if (!cmpval) {
 101                 (*end) = (*cur_rec);
 102                 return 1;
 103         }
 104         if (cmpval < 0)
 105                 (*begin) = (*cur_rec) + 1;
 106         else
 107                 *(end) = (*cur_rec) - 1;
 108
 109         return 0;
 110 }
 111
 112 /* Find the record in bnode that best matches key (not greater than...)*/
 113 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd,
 114                                         search_strategy_t rec_found)
 115 {
 116         u16 off, len, keylen;
 117         int rec;
 118         int b, e;
 119         int res;
 120
 121         BUG_ON(!rec_found);
 122         b = 0;
 123         e = bnode->num_recs - 1;
 124         res = -ENOENT;
 125         do {
 126                 rec = (e + b) / 2;
 127                 len = hfs_brec_lenoff(bnode, rec, &off);
 128                 keylen = hfs_brec_keylen(bnode, rec);
 129                 if (keylen == 0) {
 130                         res = -EINVAL;
 131                         goto fail;
 132                 }
 133                 hfs_bnode_read(bnode, fd->key, off, keylen);
 134                 if (rec_found(bnode, fd, &b, &e, &rec)) {
 135                         res = 0;
 136                         goto done;
 137                 }
 138         } while (b <= e);
 139
 140         if (rec != e && e >= 0) {
 141                 len = hfs_brec_lenoff(bnode, e, &off);
 142                 keylen = hfs_brec_keylen(bnode, e);
 143                 if (keylen == 0) {
 144                         res = -EINVAL;
 145                         goto fail;
 146                 }
 147                 hfs_bnode_read(bnode, fd->key, off, keylen);
 148         }
 149
 150 done:
 151         fd->record = e;
 152         fd->keyoffset = off;
 153         fd->keylength = keylen;
 154         fd->entryoffset = off + keylen;
 155         fd->entrylength = len - keylen;
 156
 157 fail:
 158         return res;
 159 }
 160
 161 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 162 /* Return allocated copy of node found, set recnum to best record */
 163 int hfs_brec_find(struct hfs_find_data *fd, search_strategy_t do_key_compare)
 164 {
 165         struct hfs_btree *tree;
 166         struct hfs_bnode *bnode;
 167         u32 nidx, parent;
 168         __be32 data;
 169         int height, res;
 170
 171         tree = fd->tree;
 172         if (fd->bnode)
 173                 hfs_bnode_put(fd->bnode);
 174         fd->bnode = NULL;
 175         nidx = tree->root;
 176         if (!nidx)
 177                 return -ENOENT;
 178         height = tree->depth;
 179         res = 0;
 180         parent = 0;
 181         for (;;) {
 182                 bnode = hfs_bnode_find(tree, nidx);
 183                 if (IS_ERR(bnode)) {
 184                         res = PTR_ERR(bnode);
 185                         bnode = NULL;
 186                         break;
 187                 }
 188                 if (bnode->height != height)
 189                         goto invalid;
 190                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 191                         goto invalid;
 192                 bnode->parent = parent;
 193
 194                 res = __hfs_brec_find(bnode, fd, do_key_compare);
 195                 if (!height)
 196                         break;
 197                 if (fd->record < 0)
 198                         goto release;
 199
 200                 parent = nidx;
 201                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 202                 nidx = be32_to_cpu(data);
 203                 hfs_bnode_put(bnode);
 204         }
 205         fd->bnode = bnode;
 206         return res;
 207
 208 invalid:
 209         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 210                 height, bnode->height, bnode->type, nidx, parent);
 211         res = -EIO;
 212 release:
 213         hfs_bnode_put(bnode);
 214         return res;
 215 }
 216
 217 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 218 {
 219         int res;
 220
 221         res = hfs_brec_find(fd, hfs_find_rec_by_key);
 222         if (res)
 223                 return res;
 224         if (fd->entrylength > rec_len)
 225                 return -EINVAL;
 226         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 227         return 0;
 228 }
 229
 230 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 231 {
 232         struct hfs_btree *tree;
 233         struct hfs_bnode *bnode;
 234         int idx, res = 0;
 235         u16 off, len, keylen;
 236
 237         bnode = fd->bnode;
 238         tree = bnode->tree;
 239
 240         if (cnt < 0) {
 241                 cnt = -cnt;
 242                 while (cnt > fd->record) {
 243                         cnt -= fd->record + 1;
 244                         fd->record = bnode->num_recs - 1;
 245                         idx = bnode->prev;
 246                         if (!idx) {
 247                                 res = -ENOENT;
 248                                 goto out;
 249                         }
 250                         hfs_bnode_put(bnode);
 251                         bnode = hfs_bnode_find(tree, idx);
 252                         if (IS_ERR(bnode)) {
 253                                 res = PTR_ERR(bnode);
 254                                 bnode = NULL;
 255                                 goto out;
 256                         }
 257                 }
 258                 fd->record -= cnt;
 259         } else {
 260                 while (cnt >= bnode->num_recs - fd->record) {
 261                         cnt -= bnode->num_recs - fd->record;
 262                         fd->record = 0;
 263                         idx = bnode->next;
 264                         if (!idx) {
 265                                 res = -ENOENT;
 266                                 goto out;
 267                         }
 268                         hfs_bnode_put(bnode);
 269                         bnode = hfs_bnode_find(tree, idx);
 270                         if (IS_ERR(bnode)) {
 271                                 res = PTR_ERR(bnode);
 272                                 bnode = NULL;
 273                                 goto out;
 274                         }
 275                 }
 276                 fd->record += cnt;
 277         }
 278
 279         len = hfs_brec_lenoff(bnode, fd->record, &off);
 280         keylen = hfs_brec_keylen(bnode, fd->record);
 281         if (keylen == 0) {
 282                 res = -EINVAL;
 283                 goto out;
 284         }
 285         fd->keyoffset = off;
 286         fd->keylength = keylen;
 287         fd->entryoffset = off + keylen;
 288         fd->entrylength = len - keylen;
 289         hfs_bnode_read(bnode, fd->key, off, keylen);
 290 out:
 291         fd->bnode = bnode;
 292         return res;
 293 }