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         mutex_lock(&tree->tree_lock);
  28         return 0;
  29 }
  30
  31 void hfs_find_exit(struct hfs_find_data *fd)
  32 {
  33         hfs_bnode_put(fd->bnode);
  34         kfree(fd->search_key);
  35         hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
  36                 fd->tree->cnid, __builtin_return_address(0));
  37         mutex_unlock(&fd->tree->tree_lock);
  38         fd->tree = NULL;
  39 }
  40
  41 /* Find the record in bnode that best matches key (not greater than...)*/
  42 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
  43 {
  44         int cmpval;
  45         u16 off, len, keylen;
  46         int rec;
  47         int b, e;
  48         int res;
  49
  50         b = 0;
  51         e = bnode->num_recs - 1;
  52         res = -ENOENT;
  53         do {
  54                 rec = (e + b) / 2;
  55                 len = hfs_brec_lenoff(bnode, rec, &off);
  56                 keylen = hfs_brec_keylen(bnode, rec);
  57                 if (keylen == 0) {
  58                         res = -EINVAL;
  59                         goto fail;
  60                 }
  61                 hfs_bnode_read(bnode, fd->key, off, keylen);
  62                 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  63                 if (!cmpval) {
  64                         e = rec;
  65                         res = 0;
  66                         goto done;
  67                 }
  68                 if (cmpval < 0)
  69                         b = rec + 1;
  70                 else
  71                         e = rec - 1;
  72         } while (b <= e);
  73         if (rec != e && e >= 0) {
  74                 len = hfs_brec_lenoff(bnode, e, &off);
  75                 keylen = hfs_brec_keylen(bnode, e);
  76                 if (keylen == 0) {
  77                         res = -EINVAL;
  78                         goto fail;
  79                 }
  80                 hfs_bnode_read(bnode, fd->key, off, keylen);
  81         }
  82 done:
  83         fd->record = e;
  84         fd->keyoffset = off;
  85         fd->keylength = keylen;
  86         fd->entryoffset = off + keylen;
  87         fd->entrylength = len - keylen;
  88 fail:
  89         return res;
  90 }
  91
  92 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
  93 /* Return allocated copy of node found, set recnum to best record */
  94 int hfs_brec_find(struct hfs_find_data *fd)
  95 {
  96         struct hfs_btree *tree;
  97         struct hfs_bnode *bnode;
  98         u32 nidx, parent;
  99         __be32 data;
 100         int height, res;
 101
 102         tree = fd->tree;
 103         if (fd->bnode)
 104                 hfs_bnode_put(fd->bnode);
 105         fd->bnode = NULL;
 106         nidx = tree->root;
 107         if (!nidx)
 108                 return -ENOENT;
 109         height = tree->depth;
 110         res = 0;
 111         parent = 0;
 112         for (;;) {
 113                 bnode = hfs_bnode_find(tree, nidx);
 114                 if (IS_ERR(bnode)) {
 115                         res = PTR_ERR(bnode);
 116                         bnode = NULL;
 117                         break;
 118                 }
 119                 if (bnode->height != height)
 120                         goto invalid;
 121                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 122                         goto invalid;
 123                 bnode->parent = parent;
 124
 125                 res = __hfs_brec_find(bnode, fd);
 126                 if (!height)
 127                         break;
 128                 if (fd->record < 0)
 129                         goto release;
 130
 131                 parent = nidx;
 132                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 133                 nidx = be32_to_cpu(data);
 134                 hfs_bnode_put(bnode);
 135         }
 136         fd->bnode = bnode;
 137         return res;
 138
 139 invalid:
 140         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 141                height, bnode->height, bnode->type, nidx, parent);
 142         res = -EIO;
 143 release:
 144         hfs_bnode_put(bnode);
 145         return res;
 146 }
 147
 148 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 149 {
 150         int res;
 151
 152         res = hfs_brec_find(fd);
 153         if (res)
 154                 return res;
 155         if (fd->entrylength > rec_len)
 156                 return -EINVAL;
 157         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 158         return 0;
 159 }
 160
 161 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 162 {
 163         struct hfs_btree *tree;
 164         struct hfs_bnode *bnode;
 165         int idx, res = 0;
 166         u16 off, len, keylen;
 167
 168         bnode = fd->bnode;
 169         tree = bnode->tree;
 170
 171         if (cnt < 0) {
 172                 cnt = -cnt;
 173                 while (cnt > fd->record) {
 174                         cnt -= fd->record + 1;
 175                         fd->record = bnode->num_recs - 1;
 176                         idx = bnode->prev;
 177                         if (!idx) {
 178                                 res = -ENOENT;
 179                                 goto out;
 180                         }
 181                         hfs_bnode_put(bnode);
 182                         bnode = hfs_bnode_find(tree, idx);
 183                         if (IS_ERR(bnode)) {
 184                                 res = PTR_ERR(bnode);
 185                                 bnode = NULL;
 186                                 goto out;
 187                         }
 188                 }
 189                 fd->record -= cnt;
 190         } else {
 191                 while (cnt >= bnode->num_recs - fd->record) {
 192                         cnt -= bnode->num_recs - fd->record;
 193                         fd->record = 0;
 194                         idx = bnode->next;
 195                         if (!idx) {
 196                                 res = -ENOENT;
 197                                 goto out;
 198                         }
 199                         hfs_bnode_put(bnode);
 200                         bnode = hfs_bnode_find(tree, idx);
 201                         if (IS_ERR(bnode)) {
 202                                 res = PTR_ERR(bnode);
 203                                 bnode = NULL;
 204                                 goto out;
 205                         }
 206                 }
 207                 fd->record += cnt;
 208         }
 209
 210         len = hfs_brec_lenoff(bnode, fd->record, &off);
 211         keylen = hfs_brec_keylen(bnode, fd->record);
 212         if (keylen == 0) {
 213                 res = -EINVAL;
 214                 goto out;
 215         }
 216         fd->keyoffset = off;
 217         fd->keylength = keylen;
 218         fd->entryoffset = off + keylen;
 219         fd->entrylength = len - keylen;
 220         hfs_bnode_read(bnode, fd->key, off, keylen);
 221 out:
 222         fd->bnode = bnode;
 223         return res;
 224 }