File: /usr/src/linux/fs/minix/bitmap.c
1 /*
2 * linux/fs/minix/bitmap.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 /*
8 * Modified for 680x0 by Hamish Macdonald
9 * Fixed for 680x0 by Andreas Schwab
10 */
11
12 /* bitmap.c contains the code that handles the inode and block bitmaps */
13
14 #include <linux/fs.h>
15 #include <linux/minix_fs.h>
16 #include <linux/locks.h>
17
18 #include <asm/bitops.h>
19
20 static int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };
21
22 static unsigned long count_free(struct buffer_head *map[], unsigned numblocks, __u32 numbits)
23 {
24 unsigned i, j, sum = 0;
25 struct buffer_head *bh;
26
27 for (i=0; i<numblocks-1; i++) {
28 if (!(bh=map[i]))
29 return(0);
30 for (j=0; j<BLOCK_SIZE; j++)
31 sum += nibblemap[bh->b_data[j] & 0xf]
32 + nibblemap[(bh->b_data[j]>>4) & 0xf];
33 }
34
35 if (numblocks==0 || !(bh=map[numblocks-1]))
36 return(0);
37 i = ((numbits-(numblocks-1)*BLOCK_SIZE*8)/16)*2;
38 for (j=0; j<i; j++) {
39 sum += nibblemap[bh->b_data[j] & 0xf]
40 + nibblemap[(bh->b_data[j]>>4) & 0xf];
41 }
42
43 i = numbits%16;
44 if (i!=0) {
45 i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
46 sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
47 sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
48 }
49 return(sum);
50 }
51
52 void minix_free_block(struct inode * inode, int block)
53 {
54 struct super_block * sb = inode->i_sb;
55 struct buffer_head * bh;
56 unsigned int bit,zone;
57
58 if (!sb) {
59 printk("trying to free block on nonexistent device\n");
60 return;
61 }
62 if (block < sb->u.minix_sb.s_firstdatazone ||
63 block >= sb->u.minix_sb.s_nzones) {
64 printk("trying to free block not in datazone\n");
65 return;
66 }
67 zone = block - sb->u.minix_sb.s_firstdatazone + 1;
68 bit = zone & 8191;
69 zone >>= 13;
70 if (zone >= sb->u.minix_sb.s_zmap_blocks) {
71 printk("minix_free_block: nonexistent bitmap buffer\n");
72 return;
73 }
74 bh = sb->u.minix_sb.s_zmap[zone];
75 if (!minix_test_and_clear_bit(bit,bh->b_data))
76 printk("free_block (%s:%d): bit already cleared\n",
77 kdevname(sb->s_dev), block);
78 mark_buffer_dirty(bh);
79 return;
80 }
81
82 int minix_new_block(struct inode * inode)
83 {
84 struct super_block * sb = inode->i_sb;
85 struct buffer_head * bh;
86 int i,j;
87
88 if (!sb) {
89 printk("trying to get new block from nonexistent device\n");
90 return 0;
91 }
92 repeat:
93 j = 8192;
94 bh = NULL;
95 for (i = 0; i < sb->u.minix_sb.s_zmap_blocks; i++) {
96 bh = sb->u.minix_sb.s_zmap[i];
97 if ((j = minix_find_first_zero_bit(bh->b_data, 8192)) < 8192)
98 break;
99 }
100 if (!bh || j >= 8192)
101 return 0;
102 if (minix_test_and_set_bit(j,bh->b_data)) {
103 printk("new_block: bit already set");
104 goto repeat;
105 }
106 mark_buffer_dirty(bh);
107 j += i*8192 + sb->u.minix_sb.s_firstdatazone-1;
108 if (j < sb->u.minix_sb.s_firstdatazone ||
109 j >= sb->u.minix_sb.s_nzones)
110 return 0;
111 return j;
112 }
113
114 unsigned long minix_count_free_blocks(struct super_block *sb)
115 {
116 return (count_free(sb->u.minix_sb.s_zmap, sb->u.minix_sb.s_zmap_blocks,
117 sb->u.minix_sb.s_nzones - sb->u.minix_sb.s_firstdatazone + 1)
118 << sb->u.minix_sb.s_log_zone_size);
119 }
120
121 struct minix_inode *
122 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
123 {
124 int block;
125 struct minix_sb_info *sbi = &sb->u.minix_sb;
126 struct minix_inode *p;
127
128 if (!ino || ino > sbi->s_ninodes) {
129 printk("Bad inode number on dev %s: %ld is out of range\n",
130 bdevname(sb->s_dev), ino);
131 return NULL;
132 }
133 ino--;
134 block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
135 ino / MINIX_INODES_PER_BLOCK;
136 *bh = bread(sb->s_dev, block, BLOCK_SIZE);
137 if (!*bh) {
138 printk("unable to read i-node block\n");
139 return NULL;
140 }
141 p = (void *)(*bh)->b_data;
142 return p + ino % MINIX_INODES_PER_BLOCK;
143 }
144
145 struct minix2_inode *
146 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
147 {
148 int block;
149 struct minix_sb_info *sbi = &sb->u.minix_sb;
150 struct minix2_inode *p;
151
152 *bh = NULL;
153 if (!ino || ino > sbi->s_ninodes) {
154 printk("Bad inode number on dev %s: %ld is out of range\n",
155 bdevname(sb->s_dev), ino);
156 return NULL;
157 }
158 ino--;
159 block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
160 ino / MINIX2_INODES_PER_BLOCK;
161 *bh = bread(sb->s_dev, block, BLOCK_SIZE);
162 if (!*bh) {
163 printk("unable to read i-node block\n");
164 return NULL;
165 }
166 p = (void *)(*bh)->b_data;
167 return p + ino % MINIX2_INODES_PER_BLOCK;
168 }
169
170 /* Clear the link count and mode of a deleted inode on disk. */
171
172 static void minix_clear_inode(struct inode *inode)
173 {
174 struct buffer_head *bh;
175 if (INODE_VERSION(inode) == MINIX_V1) {
176 struct minix_inode *raw_inode;
177 raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
178 if (raw_inode) {
179 raw_inode->i_nlinks = 0;
180 raw_inode->i_mode = 0;
181 }
182 } else {
183 struct minix2_inode *raw_inode;
184 raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
185 if (raw_inode) {
186 raw_inode->i_nlinks = 0;
187 raw_inode->i_mode = 0;
188 }
189 }
190 if (bh) {
191 mark_buffer_dirty(bh);
192 brelse (bh);
193 }
194 }
195
196 void minix_free_inode(struct inode * inode)
197 {
198 struct buffer_head * bh;
199 unsigned long ino;
200
201 if (inode->i_ino < 1 || inode->i_ino > inode->i_sb->u.minix_sb.s_ninodes) {
202 printk("free_inode: inode 0 or nonexistent inode\n");
203 return;
204 }
205 ino = inode->i_ino;
206 if ((ino >> 13) >= inode->i_sb->u.minix_sb.s_imap_blocks) {
207 printk("free_inode: nonexistent imap in superblock\n");
208 return;
209 }
210
211 bh = inode->i_sb->u.minix_sb.s_imap[ino >> 13];
212 minix_clear_inode(inode);
213 clear_inode(inode);
214 if (!minix_test_and_clear_bit(ino & 8191, bh->b_data))
215 printk("free_inode: bit %lu already cleared.\n",ino);
216 mark_buffer_dirty(bh);
217 }
218
219 struct inode * minix_new_inode(const struct inode * dir, int * error)
220 {
221 struct super_block * sb;
222 struct inode * inode;
223 struct buffer_head * bh;
224 int i,j;
225
226 sb = dir->i_sb;
227 inode = new_inode(sb);
228 if (!inode) {
229 *error = -ENOMEM;
230 return NULL;
231 }
232 j = 8192;
233 bh = NULL;
234 *error = -ENOSPC;
235 lock_super(sb);
236 for (i = 0; i < sb->u.minix_sb.s_imap_blocks; i++) {
237 bh = inode->i_sb->u.minix_sb.s_imap[i];
238 if ((j = minix_find_first_zero_bit(bh->b_data, 8192)) < 8192)
239 break;
240 }
241 if (!bh || j >= 8192) {
242 iput(inode);
243 unlock_super(sb);
244 return NULL;
245 }
246 if (minix_test_and_set_bit(j,bh->b_data)) { /* shouldn't happen */
247 printk("new_inode: bit already set");
248 iput(inode);
249 unlock_super(sb);
250 return NULL;
251 }
252 mark_buffer_dirty(bh);
253 j += i*8192;
254 if (!j || j > inode->i_sb->u.minix_sb.s_ninodes) {
255 iput(inode);
256 unlock_super(sb);
257 return NULL;
258 }
259 inode->i_uid = current->fsuid;
260 inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
261 inode->i_ino = j;
262 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
263 inode->i_blocks = inode->i_blksize = 0;
264 insert_inode_hash(inode);
265 mark_inode_dirty(inode);
266
267 unlock_super(sb);
268 *error = 0;
269 return inode;
270 }
271
272 unsigned long minix_count_free_inodes(struct super_block *sb)
273 {
274 return count_free(sb->u.minix_sb.s_imap, sb->u.minix_sb.s_imap_blocks,
275 sb->u.minix_sb.s_ninodes + 1);
276 }
277