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Linux/fs/minix/bitmap.c

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  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  */
 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 
 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 
 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 
 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 *
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 *
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 
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 
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 
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 
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 

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