1 /*
2 * linux/fs/super.c
3 *
4 * (C) 1991 Linus Torvalds
5 */
6
7 /*
8 * super.c contains code to handle the super-block tables.
9 */
10 #include <linux/config.h>
11 #include <linux/sched.h>
12 #include <linux/kernel.h>
13 #include <asm/system.h>
14
15 #include <errno.h>
16 #include <sys/stat.h>
17
18 int sync_dev(int dev);
19 void wait_for_keypress(void);
20
21 /* set_bit uses setb, as gas doesn't recognize setc */
22 #define set_bit(bitnr,addr) ({ \
23 register int __res __asm__("ax"); \
24 __asm__("bt %2,%3;setb %%al":"=a" (__res):"a" (0),"r" (bitnr),"m" (*(addr))); \
25 __res; })
26
27 struct super_block super_block[NR_SUPER];
28 /* this is initialized in init/main.c */
29 int ROOT_DEV = 0;
30
31 static void lock_super(struct super_block * sb)
32 {
33 cli();
34 while (sb->s_lock)
35 sleep_on(&(sb->s_wait));
36 sb->s_lock = 1;
37 sti();
38 }
39
40 static void free_super(struct super_block * sb)
41 {
42 cli();
43 sb->s_lock = 0;
44 wake_up(&(sb->s_wait));
45 sti();
46 }
47
48 static void wait_on_super(struct super_block * sb)
49 {
50 cli();
51 while (sb->s_lock)
52 sleep_on(&(sb->s_wait));
53 sti();
54 }
55
56 struct super_block * get_super(int dev)
57 {
58 struct super_block * s;
59
60 if (!dev)
61 return NULL;
62 s = 0+super_block;
63 while (s < NR_SUPER+super_block)
64 if (s->s_dev == dev) {
65 wait_on_super(s);
66 if (s->s_dev == dev)
67 return s;
68 s = 0+super_block;
69 } else
70 s++;
71 return NULL;
72 }
73
74 void put_super(int dev)
75 {
76 struct super_block * sb;
77 struct m_inode * inode;
78 int i;
79
80 if (dev == ROOT_DEV) {
81 printk("root diskette changed: prepare for armageddon\n\r");
82 return;
83 }
84 if (!(sb = get_super(dev)))
85 return;
86 if (sb->s_imount) {
87 printk("Mounted disk changed - tssk, tssk\n\r");
88 return;
89 }
90 lock_super(sb);
91 sb->s_dev = 0;
92 for(i=0;i<I_MAP_SLOTS;i++)
93 brelse(sb->s_imap[i]);
94 for(i=0;i<Z_MAP_SLOTS;i++)
95 brelse(sb->s_zmap[i]);
96 free_super(sb);
97 return;
98 }
99
100 static struct super_block * read_super(int dev)
101 {
102 struct super_block * s;
103 struct buffer_head * bh;
104 int i,block;
105
106 if (!dev)
107 return NULL;
108 check_disk_change(dev);
109 if (s = get_super(dev))
110 return s;
111 for (s = 0+super_block ;; s++) {
112 if (s >= NR_SUPER+super_block)
113 return NULL;
114 if (!s->s_dev)
115 break;
116 }
117 s->s_dev = dev;
118 s->s_isup = NULL;
119 s->s_imount = NULL;
120 s->s_time = 0;
121 s->s_rd_only = 0;
122 s->s_dirt = 0;
123 lock_super(s);
124 if (!(bh = bread(dev,1))) {
125 s->s_dev=0;
126 free_super(s);
127 return NULL;
128 }
129 *((struct d_super_block *) s) =
130 *((struct d_super_block *) bh->b_data);
131 brelse(bh);
132 if (s->s_magic != SUPER_MAGIC) {
133 s->s_dev = 0;
134 free_super(s);
135 return NULL;
136 }
137 for (i=0;i<I_MAP_SLOTS;i++)
138 s->s_imap[i] = NULL;
139 for (i=0;i<Z_MAP_SLOTS;i++)
140 s->s_zmap[i] = NULL;
141 block=2;
142 for (i=0 ; i < s->s_imap_blocks ; i++)
143 if (s->s_imap[i]=bread(dev,block))
144 block++;
145 else
146 break;
147 for (i=0 ; i < s->s_zmap_blocks ; i++)
148 if (s->s_zmap[i]=bread(dev,block))
149 block++;
150 else
151 break;
152 if (block != 2+s->s_imap_blocks+s->s_zmap_blocks) {
153 for(i=0;i<I_MAP_SLOTS;i++)
154 brelse(s->s_imap[i]);
155 for(i=0;i<Z_MAP_SLOTS;i++)
156 brelse(s->s_zmap[i]);
157 s->s_dev=0;
158 free_super(s);
159 return NULL;
160 }
161 s->s_imap[0]->b_data[0] |= 1;
162 s->s_zmap[0]->b_data[0] |= 1;
163 free_super(s);
164 return s;
165 }
166
167 int sys_umount(char * dev_name)
168 {
169 struct m_inode * inode;
170 struct super_block * sb;
171 int dev;
172
173 if (!(inode=namei(dev_name)))
174 return -ENOENT;
175 dev = inode->i_zone[0];
176 if (!S_ISBLK(inode->i_mode)) {
177 iput(inode);
178 return -ENOTBLK;
179 }
180 iput(inode);
181 if (dev==ROOT_DEV)
182 return -EBUSY;
183 if (!(sb=get_super(dev)) || !(sb->s_imount))
184 return -ENOENT;
185 if (!sb->s_imount->i_mount)
186 printk("Mounted inode has i_mount=0\n");
187 for (inode=inode_table+0 ; inode<inode_table+NR_INODE ; inode++)
188 if (inode->i_dev==dev && inode->i_count)
189 return -EBUSY;
190 sb->s_imount->i_mount=0;
191 iput(sb->s_imount);
192 sb->s_imount = NULL;
193 iput(sb->s_isup);
194 sb->s_isup = NULL;
195 put_super(dev);
196 sync_dev(dev);
197 return 0;
198 }
199
200 int sys_mount(char * dev_name, char * dir_name, int rw_flag)
201 {
202 struct m_inode * dev_i, * dir_i;
203 struct super_block * sb;
204 int dev;
205
206 if (!(dev_i=namei(dev_name)))
207 return -ENOENT;
208 dev = dev_i->i_zone[0];
209 if (!S_ISBLK(dev_i->i_mode)) {
210 iput(dev_i);
211 return -EPERM;
212 }
213 iput(dev_i);
214 if (!(dir_i=namei(dir_name)))
215 return -ENOENT;
216 if (dir_i->i_count != 1 || dir_i->i_num == ROOT_INO) {
217 iput(dir_i);
218 return -EBUSY;
219 }
220 if (!S_ISDIR(dir_i->i_mode)) {
221 iput(dir_i);
222 return -EPERM;
223 }
224 if (!(sb=read_super(dev))) {
225 iput(dir_i);
226 return -EBUSY;
227 }
228 if (sb->s_imount) {
229 iput(dir_i);
230 return -EBUSY;
231 }
232 if (dir_i->i_mount) {
233 iput(dir_i);
234 return -EPERM;
235 }
236 sb->s_imount=dir_i;
237 dir_i->i_mount=1;
238 dir_i->i_dirt=1; /* NOTE! we don't iput(dir_i) */
239 return 0; /* we do that in umount */
240 }
241
242 void mount_root(void)
243 {
244 int i,free;
245 struct super_block * p;
246 struct m_inode * mi;
247
248 if (32 != sizeof (struct d_inode))
249 panic("bad i-node size");
250 for(i=0;i<NR_FILE;i++)
251 file_table[i].f_count=0;
252 if (MAJOR(ROOT_DEV) == 2) {
253 printk("Insert root floppy and press ENTER");
254 wait_for_keypress();
255 }
256 for(p = &super_block[0] ; p < &super_block[NR_SUPER] ; p++) {
257 p->s_dev = 0;
258 p->s_lock = 0;
259 p->s_wait = NULL;
260 }
261 if (!(p=read_super(ROOT_DEV)))
262 panic("Unable to mount root");
263 if (!(mi=iget(ROOT_DEV,ROOT_INO)))
264 panic("Unable to read root i-node");
265 mi->i_count += 3 ; /* NOTE! it is logically used 4 times, not 1 */
266 p->s_isup = p->s_imount = mi;
267 current->pwd = mi;
268 current->root = mi;
269 free=0;
270 i=p->s_nzones;
271 while (-- i >= 0)
272 if (!set_bit(i&8191,p->s_zmap[i>>13]->b_data))
273 free++;
274 printk("%d/%d free blocks\n\r",free,p->s_nzones);
275 free=0;
276 i=p->s_ninodes+1;
277 while (-- i >= 0)
278 if (!set_bit(i&8191,p->s_imap[i>>13]->b_data))
279 free++;
280 printk("%d/%d free inodes\n\r",free,p->s_ninodes);
281 }
282
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