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Linux/fs/hfs/bfind.c

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  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         mutex_lock(&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         mutex_unlock(&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                 if (keylen == 0) {
 56                         res = -EINVAL;
 57                         goto fail;
 58                 }
 59                 hfs_bnode_read(bnode, fd->key, off, keylen);
 60                 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
 61                 if (!cmpval) {
 62                         e = rec;
 63                         res = 0;
 64                         goto done;
 65                 }
 66                 if (cmpval < 0)
 67                         b = rec + 1;
 68                 else
 69                         e = rec - 1;
 70         } while (b <= e);
 71         if (rec != e && e >= 0) {
 72                 len = hfs_brec_lenoff(bnode, e, &off);
 73                 keylen = hfs_brec_keylen(bnode, e);
 74                 if (keylen == 0) {
 75                         res = -EINVAL;
 76                         goto fail;
 77                 }
 78                 hfs_bnode_read(bnode, fd->key, off, keylen);
 79         }
 80 done:
 81         fd->record = e;
 82         fd->keyoffset = off;
 83         fd->keylength = keylen;
 84         fd->entryoffset = off + keylen;
 85         fd->entrylength = len - keylen;
 86 fail:
 87         return res;
 88 }
 89 
 90 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 91 /* Return allocated copy of node found, set recnum to best record */
 92 int hfs_brec_find(struct hfs_find_data *fd)
 93 {
 94         struct hfs_btree *tree;
 95         struct hfs_bnode *bnode;
 96         u32 nidx, parent;
 97         __be32 data;
 98         int height, res;
 99 
100         tree = fd->tree;
101         if (fd->bnode)
102                 hfs_bnode_put(fd->bnode);
103         fd->bnode = NULL;
104         nidx = tree->root;
105         if (!nidx)
106                 return -ENOENT;
107         height = tree->depth;
108         res = 0;
109         parent = 0;
110         for (;;) {
111                 bnode = hfs_bnode_find(tree, nidx);
112                 if (IS_ERR(bnode)) {
113                         res = PTR_ERR(bnode);
114                         bnode = NULL;
115                         break;
116                 }
117                 if (bnode->height != height)
118                         goto invalid;
119                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
120                         goto invalid;
121                 bnode->parent = parent;
122 
123                 res = __hfs_brec_find(bnode, fd);
124                 if (!height)
125                         break;
126                 if (fd->record < 0)
127                         goto release;
128 
129                 parent = nidx;
130                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
131                 nidx = be32_to_cpu(data);
132                 hfs_bnode_put(bnode);
133         }
134         fd->bnode = bnode;
135         return res;
136 
137 invalid:
138         printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
139                 height, bnode->height, bnode->type, nidx, parent);
140         res = -EIO;
141 release:
142         hfs_bnode_put(bnode);
143         return res;
144 }
145 
146 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
147 {
148         int res;
149 
150         res = hfs_brec_find(fd);
151         if (res)
152                 return res;
153         if (fd->entrylength > rec_len)
154                 return -EINVAL;
155         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
156         return 0;
157 }
158 
159 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
160 {
161         struct hfs_btree *tree;
162         struct hfs_bnode *bnode;
163         int idx, res = 0;
164         u16 off, len, keylen;
165 
166         bnode = fd->bnode;
167         tree = bnode->tree;
168 
169         if (cnt < 0) {
170                 cnt = -cnt;
171                 while (cnt > fd->record) {
172                         cnt -= fd->record + 1;
173                         fd->record = bnode->num_recs - 1;
174                         idx = bnode->prev;
175                         if (!idx) {
176                                 res = -ENOENT;
177                                 goto out;
178                         }
179                         hfs_bnode_put(bnode);
180                         bnode = hfs_bnode_find(tree, idx);
181                         if (IS_ERR(bnode)) {
182                                 res = PTR_ERR(bnode);
183                                 bnode = NULL;
184                                 goto out;
185                         }
186                 }
187                 fd->record -= cnt;
188         } else {
189                 while (cnt >= bnode->num_recs - fd->record) {
190                         cnt -= bnode->num_recs - fd->record;
191                         fd->record = 0;
192                         idx = bnode->next;
193                         if (!idx) {
194                                 res = -ENOENT;
195                                 goto out;
196                         }
197                         hfs_bnode_put(bnode);
198                         bnode = hfs_bnode_find(tree, idx);
199                         if (IS_ERR(bnode)) {
200                                 res = PTR_ERR(bnode);
201                                 bnode = NULL;
202                                 goto out;
203                         }
204                 }
205                 fd->record += cnt;
206         }
207 
208         len = hfs_brec_lenoff(bnode, fd->record, &off);
209         keylen = hfs_brec_keylen(bnode, fd->record);
210         if (keylen == 0) {
211                 res = -EINVAL;
212                 goto out;
213         }
214         fd->keyoffset = off;
215         fd->keylength = keylen;
216         fd->entryoffset = off + keylen;
217         fd->entrylength = len - keylen;
218         hfs_bnode_read(bnode, fd->key, off, keylen);
219 out:
220         fd->bnode = bnode;
221         return res;
222 }
223 

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