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1da177e4 LT |
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 | //printk("%d: %d,%d,%d\n", bnode->this, b, e, rec); | |
68 | if (rec != e && e >= 0) { | |
69 | len = hfs_brec_lenoff(bnode, e, &off); | |
70 | keylen = hfs_brec_keylen(bnode, e); | |
71 | hfs_bnode_read(bnode, fd->key, off, keylen); | |
72 | } | |
73 | done: | |
74 | fd->record = e; | |
75 | fd->keyoffset = off; | |
76 | fd->keylength = keylen; | |
77 | fd->entryoffset = off + keylen; | |
78 | fd->entrylength = len - keylen; | |
79 | return res; | |
80 | } | |
81 | ||
82 | /* Traverse a B*Tree from the root to a leaf finding best fit to key */ | |
83 | /* Return allocated copy of node found, set recnum to best record */ | |
84 | int hfs_brec_find(struct hfs_find_data *fd) | |
85 | { | |
86 | struct hfs_btree *tree; | |
87 | struct hfs_bnode *bnode; | |
88 | u32 nidx, parent; | |
89 | __be32 data; | |
90 | int height, res; | |
91 | ||
92 | tree = fd->tree; | |
93 | if (fd->bnode) | |
94 | hfs_bnode_put(fd->bnode); | |
95 | fd->bnode = NULL; | |
96 | nidx = tree->root; | |
97 | if (!nidx) | |
98 | return -ENOENT; | |
99 | height = tree->depth; | |
100 | res = 0; | |
101 | parent = 0; | |
102 | for (;;) { | |
103 | bnode = hfs_bnode_find(tree, nidx); | |
104 | if (IS_ERR(bnode)) { | |
105 | res = PTR_ERR(bnode); | |
106 | bnode = NULL; | |
107 | break; | |
108 | } | |
109 | if (bnode->height != height) | |
110 | goto invalid; | |
111 | if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF)) | |
112 | goto invalid; | |
113 | bnode->parent = parent; | |
114 | ||
115 | res = __hfs_brec_find(bnode, fd); | |
116 | if (!height) | |
117 | break; | |
118 | if (fd->record < 0) | |
119 | goto release; | |
120 | ||
121 | parent = nidx; | |
122 | hfs_bnode_read(bnode, &data, fd->entryoffset, 4); | |
123 | nidx = be32_to_cpu(data); | |
124 | hfs_bnode_put(bnode); | |
125 | } | |
126 | fd->bnode = bnode; | |
127 | return res; | |
128 | ||
129 | invalid: | |
130 | printk("HFS: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n", | |
131 | height, bnode->height, bnode->type, nidx, parent); | |
132 | res = -EIO; | |
133 | release: | |
134 | hfs_bnode_put(bnode); | |
135 | return res; | |
136 | } | |
137 | ||
138 | int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len) | |
139 | { | |
140 | int res; | |
141 | ||
142 | res = hfs_brec_find(fd); | |
143 | if (res) | |
144 | return res; | |
145 | if (fd->entrylength > rec_len) | |
146 | return -EINVAL; | |
147 | hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength); | |
148 | return 0; | |
149 | } | |
150 | ||
151 | int hfs_brec_goto(struct hfs_find_data *fd, int cnt) | |
152 | { | |
153 | struct hfs_btree *tree; | |
154 | struct hfs_bnode *bnode; | |
155 | int idx, res = 0; | |
156 | u16 off, len, keylen; | |
157 | ||
158 | bnode = fd->bnode; | |
159 | tree = bnode->tree; | |
160 | ||
161 | if (cnt < 0) { | |
162 | cnt = -cnt; | |
163 | while (cnt > fd->record) { | |
164 | cnt -= fd->record + 1; | |
165 | fd->record = bnode->num_recs - 1; | |
166 | idx = bnode->prev; | |
167 | if (!idx) { | |
168 | res = -ENOENT; | |
169 | goto out; | |
170 | } | |
171 | hfs_bnode_put(bnode); | |
172 | bnode = hfs_bnode_find(tree, idx); | |
173 | if (IS_ERR(bnode)) { | |
174 | res = PTR_ERR(bnode); | |
175 | bnode = NULL; | |
176 | goto out; | |
177 | } | |
178 | } | |
179 | fd->record -= cnt; | |
180 | } else { | |
181 | while (cnt >= bnode->num_recs - fd->record) { | |
182 | cnt -= bnode->num_recs - fd->record; | |
183 | fd->record = 0; | |
184 | idx = bnode->next; | |
185 | if (!idx) { | |
186 | res = -ENOENT; | |
187 | goto out; | |
188 | } | |
189 | hfs_bnode_put(bnode); | |
190 | bnode = hfs_bnode_find(tree, idx); | |
191 | if (IS_ERR(bnode)) { | |
192 | res = PTR_ERR(bnode); | |
193 | bnode = NULL; | |
194 | goto out; | |
195 | } | |
196 | } | |
197 | fd->record += cnt; | |
198 | } | |
199 | ||
200 | len = hfs_brec_lenoff(bnode, fd->record, &off); | |
201 | keylen = hfs_brec_keylen(bnode, fd->record); | |
202 | fd->keyoffset = off; | |
203 | fd->keylength = keylen; | |
204 | fd->entryoffset = off + keylen; | |
205 | fd->entrylength = len - keylen; | |
206 | hfs_bnode_read(bnode, fd->key, off, keylen); | |
207 | out: | |
208 | fd->bnode = bnode; | |
209 | return res; | |
210 | } |