[PATCH] fix posix lock on NFS
[linux-2.6.git] / fs / quota.c
1 /*
2  * Quota code necessary even when VFS quota support is not compiled
3  * into the kernel.  The interesting stuff is over in dquot.c, here
4  * we have symbols for initial quotactl(2) handling, the sysctl(2)
5  * variables, etc - things needed even when quota support disabled.
6  */
7
8 #include <linux/fs.h>
9 #include <linux/namei.h>
10 #include <linux/slab.h>
11 #include <asm/current.h>
12 #include <asm/uaccess.h>
13 #include <linux/kernel.h>
14 #include <linux/smp_lock.h>
15 #include <linux/security.h>
16 #include <linux/syscalls.h>
17 #include <linux/buffer_head.h>
18 #include <linux/quotaops.h>
19
20 /* Check validity of generic quotactl commands */
21 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
22 {
23         if (type >= MAXQUOTAS)
24                 return -EINVAL;
25         if (!sb && cmd != Q_SYNC)
26                 return -ENODEV;
27         /* Is operation supported? */
28         if (sb && !sb->s_qcop)
29                 return -ENOSYS;
30
31         switch (cmd) {
32                 case Q_GETFMT:
33                         break;
34                 case Q_QUOTAON:
35                         if (!sb->s_qcop->quota_on)
36                                 return -ENOSYS;
37                         break;
38                 case Q_QUOTAOFF:
39                         if (!sb->s_qcop->quota_off)
40                                 return -ENOSYS;
41                         break;
42                 case Q_SETINFO:
43                         if (!sb->s_qcop->set_info)
44                                 return -ENOSYS;
45                         break;
46                 case Q_GETINFO:
47                         if (!sb->s_qcop->get_info)
48                                 return -ENOSYS;
49                         break;
50                 case Q_SETQUOTA:
51                         if (!sb->s_qcop->set_dqblk)
52                                 return -ENOSYS;
53                         break;
54                 case Q_GETQUOTA:
55                         if (!sb->s_qcop->get_dqblk)
56                                 return -ENOSYS;
57                         break;
58                 case Q_SYNC:
59                         if (sb && !sb->s_qcop->quota_sync)
60                                 return -ENOSYS;
61                         break;
62                 default:
63                         return -EINVAL;
64         }
65
66         /* Is quota turned on for commands which need it? */
67         switch (cmd) {
68                 case Q_GETFMT:
69                 case Q_GETINFO:
70                 case Q_QUOTAOFF:
71                 case Q_SETINFO:
72                 case Q_SETQUOTA:
73                 case Q_GETQUOTA:
74                         /* This is just informative test so we are satisfied without a lock */
75                         if (!sb_has_quota_enabled(sb, type))
76                                 return -ESRCH;
77         }
78
79         /* Check privileges */
80         if (cmd == Q_GETQUOTA) {
81                 if (((type == USRQUOTA && current->euid != id) ||
82                      (type == GRPQUOTA && !in_egroup_p(id))) &&
83                     !capable(CAP_SYS_ADMIN))
84                         return -EPERM;
85         }
86         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
87                 if (!capable(CAP_SYS_ADMIN))
88                         return -EPERM;
89
90         return 0;
91 }
92
93 /* Check validity of XFS Quota Manager commands */
94 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
95 {
96         if (type >= XQM_MAXQUOTAS)
97                 return -EINVAL;
98         if (!sb)
99                 return -ENODEV;
100         if (!sb->s_qcop)
101                 return -ENOSYS;
102
103         switch (cmd) {
104                 case Q_XQUOTAON:
105                 case Q_XQUOTAOFF:
106                 case Q_XQUOTARM:
107                         if (!sb->s_qcop->set_xstate)
108                                 return -ENOSYS;
109                         break;
110                 case Q_XGETQSTAT:
111                         if (!sb->s_qcop->get_xstate)
112                                 return -ENOSYS;
113                         break;
114                 case Q_XSETQLIM:
115                         if (!sb->s_qcop->set_xquota)
116                                 return -ENOSYS;
117                         break;
118                 case Q_XGETQUOTA:
119                         if (!sb->s_qcop->get_xquota)
120                                 return -ENOSYS;
121                         break;
122                 case Q_XQUOTASYNC:
123                         if (!sb->s_qcop->quota_sync)
124                                 return -ENOSYS;
125                         break;
126                 default:
127                         return -EINVAL;
128         }
129
130         /* Check privileges */
131         if (cmd == Q_XGETQUOTA) {
132                 if (((type == XQM_USRQUOTA && current->euid != id) ||
133                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
134                      !capable(CAP_SYS_ADMIN))
135                         return -EPERM;
136         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
137                 if (!capable(CAP_SYS_ADMIN))
138                         return -EPERM;
139         }
140
141         return 0;
142 }
143
144 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
145 {
146         int error;
147
148         if (XQM_COMMAND(cmd))
149                 error = xqm_quotactl_valid(sb, type, cmd, id);
150         else
151                 error = generic_quotactl_valid(sb, type, cmd, id);
152         if (!error)
153                 error = security_quotactl(cmd, type, id, sb);
154         return error;
155 }
156
157 static void quota_sync_sb(struct super_block *sb, int type)
158 {
159         int cnt;
160         struct inode *discard[MAXQUOTAS];
161
162         sb->s_qcop->quota_sync(sb, type);
163         /* This is not very clever (and fast) but currently I don't know about
164          * any other simple way of getting quota data to disk and we must get
165          * them there for userspace to be visible... */
166         if (sb->s_op->sync_fs)
167                 sb->s_op->sync_fs(sb, 1);
168         sync_blockdev(sb->s_bdev);
169
170         /* Now when everything is written we can discard the pagecache so
171          * that userspace sees the changes. We need i_sem and so we could
172          * not do it inside dqonoff_sem. Moreover we need to be carefull
173          * about races with quotaoff() (that is the reason why we have own
174          * reference to inode). */
175         down(&sb_dqopt(sb)->dqonoff_sem);
176         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
177                 discard[cnt] = NULL;
178                 if (type != -1 && cnt != type)
179                         continue;
180                 if (!sb_has_quota_enabled(sb, cnt))
181                         continue;
182                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
183         }
184         up(&sb_dqopt(sb)->dqonoff_sem);
185         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
186                 if (discard[cnt]) {
187                         down(&discard[cnt]->i_sem);
188                         truncate_inode_pages(&discard[cnt]->i_data, 0);
189                         up(&discard[cnt]->i_sem);
190                         iput(discard[cnt]);
191                 }
192         }
193 }
194
195 void sync_dquots(struct super_block *sb, int type)
196 {
197         int cnt, dirty;
198
199         if (sb) {
200                 if (sb->s_qcop->quota_sync)
201                         quota_sync_sb(sb, type);
202                 return;
203         }
204
205         spin_lock(&sb_lock);
206 restart:
207         list_for_each_entry(sb, &super_blocks, s_list) {
208                 /* This test just improves performance so it needn't be reliable... */
209                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
210                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
211                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
212                                 dirty = 1;
213                 if (!dirty)
214                         continue;
215                 sb->s_count++;
216                 spin_unlock(&sb_lock);
217                 down_read(&sb->s_umount);
218                 if (sb->s_root && sb->s_qcop->quota_sync)
219                         quota_sync_sb(sb, type);
220                 up_read(&sb->s_umount);
221                 spin_lock(&sb_lock);
222                 if (__put_super_and_need_restart(sb))
223                         goto restart;
224         }
225         spin_unlock(&sb_lock);
226 }
227
228 /* Copy parameters and call proper function */
229 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
230 {
231         int ret;
232
233         switch (cmd) {
234                 case Q_QUOTAON: {
235                         char *pathname;
236
237                         if (IS_ERR(pathname = getname(addr)))
238                                 return PTR_ERR(pathname);
239                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
240                         putname(pathname);
241                         return ret;
242                 }
243                 case Q_QUOTAOFF:
244                         return sb->s_qcop->quota_off(sb, type);
245
246                 case Q_GETFMT: {
247                         __u32 fmt;
248
249                         down_read(&sb_dqopt(sb)->dqptr_sem);
250                         if (!sb_has_quota_enabled(sb, type)) {
251                                 up_read(&sb_dqopt(sb)->dqptr_sem);
252                                 return -ESRCH;
253                         }
254                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
255                         up_read(&sb_dqopt(sb)->dqptr_sem);
256                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
257                                 return -EFAULT;
258                         return 0;
259                 }
260                 case Q_GETINFO: {
261                         struct if_dqinfo info;
262
263                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
264                                 return ret;
265                         if (copy_to_user(addr, &info, sizeof(info)))
266                                 return -EFAULT;
267                         return 0;
268                 }
269                 case Q_SETINFO: {
270                         struct if_dqinfo info;
271
272                         if (copy_from_user(&info, addr, sizeof(info)))
273                                 return -EFAULT;
274                         return sb->s_qcop->set_info(sb, type, &info);
275                 }
276                 case Q_GETQUOTA: {
277                         struct if_dqblk idq;
278
279                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
280                                 return ret;
281                         if (copy_to_user(addr, &idq, sizeof(idq)))
282                                 return -EFAULT;
283                         return 0;
284                 }
285                 case Q_SETQUOTA: {
286                         struct if_dqblk idq;
287
288                         if (copy_from_user(&idq, addr, sizeof(idq)))
289                                 return -EFAULT;
290                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
291                 }
292                 case Q_SYNC:
293                         sync_dquots(sb, type);
294                         return 0;
295
296                 case Q_XQUOTAON:
297                 case Q_XQUOTAOFF:
298                 case Q_XQUOTARM: {
299                         __u32 flags;
300
301                         if (copy_from_user(&flags, addr, sizeof(flags)))
302                                 return -EFAULT;
303                         return sb->s_qcop->set_xstate(sb, flags, cmd);
304                 }
305                 case Q_XGETQSTAT: {
306                         struct fs_quota_stat fqs;
307                 
308                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
309                                 return ret;
310                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
311                                 return -EFAULT;
312                         return 0;
313                 }
314                 case Q_XSETQLIM: {
315                         struct fs_disk_quota fdq;
316
317                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
318                                 return -EFAULT;
319                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
320                 }
321                 case Q_XGETQUOTA: {
322                         struct fs_disk_quota fdq;
323
324                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
325                                 return ret;
326                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
327                                 return -EFAULT;
328                         return 0;
329                 }
330                 case Q_XQUOTASYNC:
331                         return sb->s_qcop->quota_sync(sb, type);
332                 /* We never reach here unless validity check is broken */
333                 default:
334                         BUG();
335         }
336         return 0;
337 }
338
339 /*
340  * This is the system call interface. This communicates with
341  * the user-level programs. Currently this only supports diskquota
342  * calls. Maybe we need to add the process quotas etc. in the future,
343  * but we probably should use rlimits for that.
344  */
345 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
346 {
347         uint cmds, type;
348         struct super_block *sb = NULL;
349         struct block_device *bdev;
350         char *tmp;
351         int ret;
352
353         cmds = cmd >> SUBCMDSHIFT;
354         type = cmd & SUBCMDMASK;
355
356         if (cmds != Q_SYNC || special) {
357                 tmp = getname(special);
358                 if (IS_ERR(tmp))
359                         return PTR_ERR(tmp);
360                 bdev = lookup_bdev(tmp);
361                 putname(tmp);
362                 if (IS_ERR(bdev))
363                         return PTR_ERR(bdev);
364                 sb = get_super(bdev);
365                 bdput(bdev);
366                 if (!sb)
367                         return -ENODEV;
368         }
369
370         ret = check_quotactl_valid(sb, type, cmds, id);
371         if (ret >= 0)
372                 ret = do_quotactl(sb, type, cmds, id, addr);
373         if (sb)
374                 drop_super(sb);
375
376         return ret;
377 }