fs/hfs/bfind.c

   1 /*
   2  *  linux/fs/hfs/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 "btree.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 HFS_CAT_CNID:
  29                 mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
  30                 break;
  31         case HFS_EXT_CNID:
  32                 mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
  33                 break;
  34         case HFS_ATTR_CNID:
  35                 mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
  36                 break;
  37         default:
  38                 return -EINVAL;
  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 /* Find the record in bnode that best matches key (not greater than...)*/
  54 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
  55 {
  56         int cmpval;
  57         u16 off, len, keylen;
  58         int rec;
  59         int b, e;
  60         int res;
  61
  62         b = 0;
  63         e = bnode->num_recs - 1;
  64         res = -ENOENT;
  65         do {
  66                 rec = (e + b) / 2;
  67                 len = hfs_brec_lenoff(bnode, rec, &off);
  68                 keylen = hfs_brec_keylen(bnode, rec);
  69                 if (keylen == 0) {
  70                         res = -EINVAL;
  71                         goto fail;
  72                 }
  73                 hfs_bnode_read(bnode, fd->key, off, keylen);
  74                 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  75                 if (!cmpval) {
  76                         e = rec;
  77                         res = 0;
  78                         goto done;
  79                 }
  80                 if (cmpval < 0)
  81                         b = rec + 1;
  82                 else
  83                         e = rec - 1;
  84         } while (b <= e);
  85         if (rec != e && e >= 0) {
  86                 len = hfs_brec_lenoff(bnode, e, &off);
  87                 keylen = hfs_brec_keylen(bnode, e);
  88                 if (keylen == 0) {
  89                         res = -EINVAL;
  90                         goto fail;
  91                 }
  92                 hfs_bnode_read(bnode, fd->key, off, keylen);
  93         }
  94 done:
  95         fd->record = e;
  96         fd->keyoffset = off;
  97         fd->keylength = keylen;
  98         fd->entryoffset = off + keylen;
  99         fd->entrylength = len - keylen;
 100 fail:
 101         return res;
 102 }
 103
 104 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 105 /* Return allocated copy of node found, set recnum to best record */
 106 int hfs_brec_find(struct hfs_find_data *fd)
 107 {
 108         struct hfs_btree *tree;
 109         struct hfs_bnode *bnode;
 110         u32 nidx, parent;
 111         __be32 data;
 112         int height, res;
 113
 114         tree = fd->tree;
 115         if (fd->bnode)
 116                 hfs_bnode_put(fd->bnode);
 117         fd->bnode = NULL;
 118         nidx = tree->root;
 119         if (!nidx)
 120                 return -ENOENT;
 121         height = tree->depth;
 122         res = 0;
 123         parent = 0;
 124         for (;;) {
 125                 bnode = hfs_bnode_find(tree, nidx);
 126                 if (IS_ERR(bnode)) {
 127                         res = PTR_ERR(bnode);
 128                         bnode = NULL;
 129                         break;
 130                 }
 131                 if (bnode->height != height)
 132                         goto invalid;
 133                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 134                         goto invalid;
 135                 bnode->parent = parent;
 136
 137                 res = __hfs_brec_find(bnode, fd);
 138                 if (!height)
 139                         break;
 140                 if (fd->record < 0)
 141                         goto release;
 142
 143                 parent = nidx;
 144                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 145                 nidx = be32_to_cpu(data);
 146                 hfs_bnode_put(bnode);
 147         }
 148         fd->bnode = bnode;
 149         return res;
 150
 151 invalid:
 152         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 153                height, bnode->height, bnode->type, nidx, parent);
 154         res = -EIO;
 155 release:
 156         hfs_bnode_put(bnode);
 157         return res;
 158 }
 159
 160 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 161 {
 162         int res;
 163
 164         res = hfs_brec_find(fd);
 165         if (res)
 166                 return res;
 167         if (fd->entrylength > rec_len)
 168                 return -EINVAL;
 169         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 170         return 0;
 171 }
 172
 173 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 174 {
 175         struct hfs_btree *tree;
 176         struct hfs_bnode *bnode;
 177         int idx, res = 0;
 178         u16 off, len, keylen;
 179
 180         bnode = fd->bnode;
 181         tree = bnode->tree;
 182
 183         if (cnt < 0) {
 184                 cnt = -cnt;
 185                 while (cnt > fd->record) {
 186                         cnt -= fd->record + 1;
 187                         fd->record = bnode->num_recs - 1;
 188                         idx = bnode->prev;
 189                         if (!idx) {
 190                                 res = -ENOENT;
 191                                 goto out;
 192                         }
 193                         hfs_bnode_put(bnode);
 194                         bnode = hfs_bnode_find(tree, idx);
 195                         if (IS_ERR(bnode)) {
 196                                 res = PTR_ERR(bnode);
 197                                 bnode = NULL;
 198                                 goto out;
 199                         }
 200                 }
 201                 fd->record -= cnt;
 202         } else {
 203                 while (cnt >= bnode->num_recs - fd->record) {
 204                         cnt -= bnode->num_recs - fd->record;
 205                         fd->record = 0;
 206                         idx = bnode->next;
 207                         if (!idx) {
 208                                 res = -ENOENT;
 209                                 goto out;
 210                         }
 211                         hfs_bnode_put(bnode);
 212                         bnode = hfs_bnode_find(tree, idx);
 213                         if (IS_ERR(bnode)) {
 214                                 res = PTR_ERR(bnode);
 215                                 bnode = NULL;
 216                                 goto out;
 217                         }
 218                 }
 219                 fd->record += cnt;
 220         }
 221
 222         len = hfs_brec_lenoff(bnode, fd->record, &off);
 223         keylen = hfs_brec_keylen(bnode, fd->record);
 224         if (keylen == 0) {
 225                 res = -EINVAL;
 226                 goto out;
 227         }
 228         fd->keyoffset = off;
 229         fd->keylength = keylen;
 230         fd->entryoffset = off + keylen;
 231         fd->entrylength = len - keylen;
 232         hfs_bnode_read(bnode, fd->key, off, keylen);
 233 out:
 234         fd->bnode = bnode;
 235         return res;
 236 }