1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/minix/bitmap.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8 /*
9 * Modified for 680x0 by Hamish Macdonald
10 * Fixed for 680x0 by Andreas Schwab
11 */
12
13 /* bitmap.c contains the code that handles the inode and block bitmaps */
14
15 #include "minix.h"
16 #include <linux/buffer_head.h>
17 #include <linux/bitops.h>
18 #include <linux/sched.h>
19
20 static DEFINE_SPINLOCK(bitmap_lock);
21
22 /*
23 * bitmap consists of blocks filled with 16bit words
24 * bit set == busy, bit clear == free
25 * endianness is a mess, but for counting zero bits it really doesn't matter...
26 */
count_free(struct buffer_head * map[],unsigned blocksize,__u32 numbits)27 static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
28 {
29 __u32 sum = 0;
30 unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
31
32 while (blocks--) {
33 unsigned words = blocksize / 2;
34 __u16 *p = (__u16 *)(*map++)->b_data;
35 while (words--)
36 sum += 16 - hweight16(*p++);
37 }
38
39 return sum;
40 }
41
minix_free_block(struct inode * inode,unsigned long block)42 void minix_free_block(struct inode *inode, unsigned long block)
43 {
44 struct super_block *sb = inode->i_sb;
45 struct minix_sb_info *sbi = minix_sb(sb);
46 struct buffer_head *bh;
47 int k = sb->s_blocksize_bits + 3;
48 unsigned long bit, zone;
49
50 if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
51 printk("Trying to free block not in datazone\n");
52 return;
53 }
54 zone = block - sbi->s_firstdatazone + 1;
55 bit = zone & ((1<<k) - 1);
56 zone >>= k;
57 if (zone >= sbi->s_zmap_blocks) {
58 printk("minix_free_block: nonexistent bitmap buffer\n");
59 return;
60 }
61 bh = sbi->s_zmap[zone];
62 spin_lock(&bitmap_lock);
63 if (!minix_test_and_clear_bit(bit, bh->b_data))
64 printk("minix_free_block (%s:%lu): bit already cleared\n",
65 sb->s_id, block);
66 spin_unlock(&bitmap_lock);
67 mark_buffer_dirty(bh);
68 return;
69 }
70
minix_new_block(struct inode * inode)71 int minix_new_block(struct inode * inode)
72 {
73 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
74 int bits_per_zone = 8 * inode->i_sb->s_blocksize;
75 int i;
76
77 for (i = 0; i < sbi->s_zmap_blocks; i++) {
78 struct buffer_head *bh = sbi->s_zmap[i];
79 int j;
80
81 spin_lock(&bitmap_lock);
82 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
83 if (j < bits_per_zone) {
84 minix_set_bit(j, bh->b_data);
85 spin_unlock(&bitmap_lock);
86 mark_buffer_dirty(bh);
87 j += i * bits_per_zone + sbi->s_firstdatazone-1;
88 if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
89 break;
90 return j;
91 }
92 spin_unlock(&bitmap_lock);
93 }
94 return 0;
95 }
96
minix_count_free_blocks(struct super_block * sb)97 unsigned long minix_count_free_blocks(struct super_block *sb)
98 {
99 struct minix_sb_info *sbi = minix_sb(sb);
100 u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;
101
102 return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
103 << sbi->s_log_zone_size);
104 }
105
106 struct minix_inode *
minix_V1_raw_inode(struct super_block * sb,ino_t ino,struct buffer_head ** bh)107 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
108 {
109 int block;
110 struct minix_sb_info *sbi = minix_sb(sb);
111 struct minix_inode *p;
112
113 if (!ino || ino > sbi->s_ninodes) {
114 printk("Bad inode number on dev %s: %ld is out of range\n",
115 sb->s_id, (long)ino);
116 return NULL;
117 }
118 ino--;
119 block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
120 ino / MINIX_INODES_PER_BLOCK;
121 *bh = sb_bread(sb, block);
122 if (!*bh) {
123 printk("Unable to read inode block\n");
124 return NULL;
125 }
126 p = (void *)(*bh)->b_data;
127 return p + ino % MINIX_INODES_PER_BLOCK;
128 }
129
130 struct minix2_inode *
minix_V2_raw_inode(struct super_block * sb,ino_t ino,struct buffer_head ** bh)131 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
132 {
133 int block;
134 struct minix_sb_info *sbi = minix_sb(sb);
135 struct minix2_inode *p;
136 int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
137
138 *bh = NULL;
139 if (!ino || ino > sbi->s_ninodes) {
140 printk("Bad inode number on dev %s: %ld is out of range\n",
141 sb->s_id, (long)ino);
142 return NULL;
143 }
144 ino--;
145 block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
146 ino / minix2_inodes_per_block;
147 *bh = sb_bread(sb, block);
148 if (!*bh) {
149 printk("Unable to read inode block\n");
150 return NULL;
151 }
152 p = (void *)(*bh)->b_data;
153 return p + ino % minix2_inodes_per_block;
154 }
155
156 /* Clear the link count and mode of a deleted inode on disk. */
157
minix_clear_inode(struct inode * inode)158 static void minix_clear_inode(struct inode *inode)
159 {
160 struct buffer_head *bh = NULL;
161
162 if (INODE_VERSION(inode) == MINIX_V1) {
163 struct minix_inode *raw_inode;
164 raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
165 if (raw_inode) {
166 raw_inode->i_nlinks = 0;
167 raw_inode->i_mode = 0;
168 }
169 } else {
170 struct minix2_inode *raw_inode;
171 raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
172 if (raw_inode) {
173 raw_inode->i_nlinks = 0;
174 raw_inode->i_mode = 0;
175 }
176 }
177 if (bh) {
178 mark_buffer_dirty(bh);
179 brelse (bh);
180 }
181 }
182
minix_free_inode(struct inode * inode)183 void minix_free_inode(struct inode * inode)
184 {
185 struct super_block *sb = inode->i_sb;
186 struct minix_sb_info *sbi = minix_sb(inode->i_sb);
187 struct buffer_head *bh;
188 int k = sb->s_blocksize_bits + 3;
189 unsigned long ino, bit;
190
191 ino = inode->i_ino;
192 if (ino < 1 || ino > sbi->s_ninodes) {
193 printk("minix_free_inode: inode 0 or nonexistent inode\n");
194 return;
195 }
196 bit = ino & ((1<<k) - 1);
197 ino >>= k;
198 if (ino >= sbi->s_imap_blocks) {
199 printk("minix_free_inode: nonexistent imap in superblock\n");
200 return;
201 }
202
203 minix_clear_inode(inode); /* clear on-disk copy */
204
205 bh = sbi->s_imap[ino];
206 spin_lock(&bitmap_lock);
207 if (!minix_test_and_clear_bit(bit, bh->b_data))
208 printk("minix_free_inode: bit %lu already cleared\n", bit);
209 spin_unlock(&bitmap_lock);
210 mark_buffer_dirty(bh);
211 }
212
minix_new_inode(const struct inode * dir,umode_t mode,int * error)213 struct inode *minix_new_inode(const struct inode *dir, umode_t mode, int *error)
214 {
215 struct super_block *sb = dir->i_sb;
216 struct minix_sb_info *sbi = minix_sb(sb);
217 struct inode *inode = new_inode(sb);
218 struct buffer_head * bh;
219 int bits_per_zone = 8 * sb->s_blocksize;
220 unsigned long j;
221 int i;
222
223 if (!inode) {
224 *error = -ENOMEM;
225 return NULL;
226 }
227 j = bits_per_zone;
228 bh = NULL;
229 *error = -ENOSPC;
230 spin_lock(&bitmap_lock);
231 for (i = 0; i < sbi->s_imap_blocks; i++) {
232 bh = sbi->s_imap[i];
233 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
234 if (j < bits_per_zone)
235 break;
236 }
237 if (!bh || j >= bits_per_zone) {
238 spin_unlock(&bitmap_lock);
239 iput(inode);
240 return NULL;
241 }
242 if (minix_test_and_set_bit(j, bh->b_data)) { /* shouldn't happen */
243 spin_unlock(&bitmap_lock);
244 printk("minix_new_inode: bit already set\n");
245 iput(inode);
246 return NULL;
247 }
248 spin_unlock(&bitmap_lock);
249 mark_buffer_dirty(bh);
250 j += i * bits_per_zone;
251 if (!j || j > sbi->s_ninodes) {
252 iput(inode);
253 return NULL;
254 }
255 inode_init_owner(inode, dir, mode);
256 inode->i_ino = j;
257 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
258 inode->i_blocks = 0;
259 memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
260 insert_inode_hash(inode);
261 mark_inode_dirty(inode);
262
263 *error = 0;
264 return inode;
265 }
266
minix_count_free_inodes(struct super_block * sb)267 unsigned long minix_count_free_inodes(struct super_block *sb)
268 {
269 struct minix_sb_info *sbi = minix_sb(sb);
270 u32 bits = sbi->s_ninodes + 1;
271
272 return count_free(sbi->s_imap, sb->s_blocksize, bits);
273 }
274