fs/hfs/bfind.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/hfs/bfind.c
   4  *
   5  * Copyright (C) 2001
   6  * Brad Boyer (flar@allandria.com)
   7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   8  *
   9  * Search routines for btrees
  10  */
  11
  12 #include <linux/slab.h>
  13 #include "btree.h"
  14
  15 int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
  16 {
  17         void *ptr;
  18
  19         fd->tree = tree;
  20         fd->bnode = NULL;
  21         ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
  22         if (!ptr)
  23                 return -ENOMEM;
  24         fd->search_key = ptr;
  25         fd->key = ptr + tree->max_key_len + 2;
  26         hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
  27                 tree->cnid, __builtin_return_address(0));
  28         switch (tree->cnid) {
  29         case HFS_CAT_CNID:
  30                 mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
  31                 break;
  32         case HFS_EXT_CNID:
  33                 mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
  34                 break;
  35         case HFS_ATTR_CNID:
  36                 mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
  37                 break;
  38         default:
  39                 return -EINVAL;
  40         }
  41         return 0;
  42 }
  43
  44 void hfs_find_exit(struct hfs_find_data *fd)
  45 {
  46         hfs_bnode_put(fd->bnode);
  47         kfree(fd->search_key);
  48         hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
  49                 fd->tree->cnid, __builtin_return_address(0));
  50         mutex_unlock(&fd->tree->tree_lock);
  51         fd->tree = NULL;
  52 }
  53
  54 /* Find the record in bnode that best matches key (not greater than...)*/
  55 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
  56 {
  57         int cmpval;
  58         u16 off, len, keylen;
  59         int rec;
  60         int b, e;
  61         int res;
  62
  63         b = 0;
  64         e = bnode->num_recs - 1;
  65         res = -ENOENT;
  66         do {
  67                 rec = (e + b) / 2;
  68                 len = hfs_brec_lenoff(bnode, rec, &off);
  69                 keylen = hfs_brec_keylen(bnode, rec);
  70                 if (keylen == 0) {
  71                         res = -EINVAL;
  72                         goto fail;
  73                 }
  74                 hfs_bnode_read(bnode, fd->key, off, keylen);
  75                 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  76                 if (!cmpval) {
  77                         e = rec;
  78                         res = 0;
  79                         goto done;
  80                 }
  81                 if (cmpval < 0)
  82                         b = rec + 1;
  83                 else
  84                         e = rec - 1;
  85         } while (b <= e);
  86         if (rec != e && e >= 0) {
  87                 len = hfs_brec_lenoff(bnode, e, &off);
  88                 keylen = hfs_brec_keylen(bnode, e);
  89                 if (keylen == 0) {
  90                         res = -EINVAL;
  91                         goto fail;
  92                 }
  93                 hfs_bnode_read(bnode, fd->key, off, keylen);
  94         }
  95 done:
  96         fd->record = e;
  97         fd->keyoffset = off;
  98         fd->keylength = keylen;
  99         fd->entryoffset = off + keylen;
 100         fd->entrylength = len - keylen;
 101 fail:
 102         return res;
 103 }
 104
 105 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 106 /* Return allocated copy of node found, set recnum to best record */
 107 int hfs_brec_find(struct hfs_find_data *fd)
 108 {
 109         struct hfs_btree *tree;
 110         struct hfs_bnode *bnode;
 111         u32 nidx, parent;
 112         __be32 data;
 113         int height, res;
 114
 115         tree = fd->tree;
 116         if (fd->bnode)
 117                 hfs_bnode_put(fd->bnode);
 118         fd->bnode = NULL;
 119         nidx = tree->root;
 120         if (!nidx)
 121                 return -ENOENT;
 122         height = tree->depth;
 123         res = 0;
 124         parent = 0;
 125         for (;;) {
 126                 bnode = hfs_bnode_find(tree, nidx);
 127                 if (IS_ERR(bnode)) {
 128                         res = PTR_ERR(bnode);
 129                         bnode = NULL;
 130                         break;
 131                 }
 132                 if (bnode->height != height)
 133                         goto invalid;
 134                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 135                         goto invalid;
 136                 bnode->parent = parent;
 137
 138                 res = __hfs_brec_find(bnode, fd);
 139                 if (!height)
 140                         break;
 141                 if (fd->record < 0)
 142                         goto release;
 143
 144                 parent = nidx;
 145                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 146                 nidx = be32_to_cpu(data);
 147                 hfs_bnode_put(bnode);
 148         }
 149         fd->bnode = bnode;
 150         return res;
 151
 152 invalid:
 153         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 154                height, bnode->height, bnode->type, nidx, parent);
 155         res = -EIO;
 156 release:
 157         hfs_bnode_put(bnode);
 158         return res;
 159 }
 160
 161 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 162 {
 163         int res;
 164
 165         res = hfs_brec_find(fd);
 166         if (res)
 167                 return res;
 168         if (fd->entrylength > rec_len)
 169                 return -EINVAL;
 170         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 171         return 0;
 172 }
 173
 174 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 175 {
 176         struct hfs_btree *tree;
 177         struct hfs_bnode *bnode;
 178         int idx, res = 0;
 179         u16 off, len, keylen;
 180
 181         bnode = fd->bnode;
 182         tree = bnode->tree;
 183
 184         if (cnt < 0) {
 185                 cnt = -cnt;
 186                 while (cnt > fd->record) {
 187                         cnt -= fd->record + 1;
 188                         fd->record = bnode->num_recs - 1;
 189                         idx = bnode->prev;
 190                         if (!idx) {
 191                                 res = -ENOENT;
 192                                 goto out;
 193                         }
 194                         hfs_bnode_put(bnode);
 195                         bnode = hfs_bnode_find(tree, idx);
 196                         if (IS_ERR(bnode)) {
 197                                 res = PTR_ERR(bnode);
 198                                 bnode = NULL;
 199                                 goto out;
 200                         }
 201                 }
 202                 fd->record -= cnt;
 203         } else {
 204                 while (cnt >= bnode->num_recs - fd->record) {
 205                         cnt -= bnode->num_recs - fd->record;
 206                         fd->record = 0;
 207                         idx = bnode->next;
 208                         if (!idx) {
 209                                 res = -ENOENT;
 210                                 goto out;
 211                         }
 212                         hfs_bnode_put(bnode);
 213                         bnode = hfs_bnode_find(tree, idx);
 214                         if (IS_ERR(bnode)) {
 215                                 res = PTR_ERR(bnode);
 216                                 bnode = NULL;
 217                                 goto out;
 218                         }
 219                 }
 220                 fd->record += cnt;
 221         }
 222
 223         len = hfs_brec_lenoff(bnode, fd->record, &off);
 224         keylen = hfs_brec_keylen(bnode, fd->record);
 225         if (keylen == 0) {
 226                 res = -EINVAL;
 227                 goto out;
 228         }
 229         fd->keyoffset = off;
 230         fd->keylength = keylen;
 231         fd->entryoffset = off + keylen;
 232         fd->entrylength = len - keylen;
 233         hfs_bnode_read(bnode, fd->key, off, keylen);
 234 out:
 235         fd->bnode = bnode;
 236         return res;
 237 }