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