Convert simple loops over superblocks to list_for_each_entry_safe
[linux-3.10.git] / fs / quota / 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/security.h>
15 #include <linux/syscalls.h>
16 #include <linux/buffer_head.h>
17 #include <linux/capability.h>
18 #include <linux/quotaops.h>
19 #include <linux/types.h>
20 #include <linux/writeback.h>
21
22 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
23                                      qid_t id)
24 {
25         switch (cmd) {
26         /* these commands do not require any special privilegues */
27         case Q_GETFMT:
28         case Q_SYNC:
29         case Q_GETINFO:
30         case Q_XGETQSTAT:
31         case Q_XQUOTASYNC:
32                 break;
33         /* allow to query information for dquots we "own" */
34         case Q_GETQUOTA:
35         case Q_XGETQUOTA:
36                 if ((type == USRQUOTA && current_euid() == id) ||
37                     (type == GRPQUOTA && in_egroup_p(id)))
38                         break;
39                 /*FALLTHROUGH*/
40         default:
41                 if (!capable(CAP_SYS_ADMIN))
42                         return -EPERM;
43         }
44
45         return security_quotactl(cmd, type, id, sb);
46 }
47
48 static int quota_sync_all(int type)
49 {
50         struct super_block *sb, *n;
51         int ret;
52
53         if (type >= MAXQUOTAS)
54                 return -EINVAL;
55         ret = security_quotactl(Q_SYNC, type, 0, NULL);
56         if (ret)
57                 return ret;
58
59         spin_lock(&sb_lock);
60         list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
61                 if (list_empty(&sb->s_instances))
62                         continue;
63                 if (!sb->s_qcop || !sb->s_qcop->quota_sync)
64                         continue;
65
66                 sb->s_count++;
67                 spin_unlock(&sb_lock);
68                 down_read(&sb->s_umount);
69                 if (sb->s_root)
70                         sb->s_qcop->quota_sync(sb, type, 1);
71                 up_read(&sb->s_umount);
72                 spin_lock(&sb_lock);
73                 __put_super(sb);
74         }
75         spin_unlock(&sb_lock);
76
77         return 0;
78 }
79
80 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
81                          void __user *addr)
82 {
83         char *pathname;
84         int ret = -ENOSYS;
85
86         pathname = getname(addr);
87         if (IS_ERR(pathname))
88                 return PTR_ERR(pathname);
89         if (sb->s_qcop->quota_on)
90                 ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
91         putname(pathname);
92         return ret;
93 }
94
95 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
96 {
97         __u32 fmt;
98
99         down_read(&sb_dqopt(sb)->dqptr_sem);
100         if (!sb_has_quota_active(sb, type)) {
101                 up_read(&sb_dqopt(sb)->dqptr_sem);
102                 return -ESRCH;
103         }
104         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
105         up_read(&sb_dqopt(sb)->dqptr_sem);
106         if (copy_to_user(addr, &fmt, sizeof(fmt)))
107                 return -EFAULT;
108         return 0;
109 }
110
111 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
112 {
113         struct if_dqinfo info;
114         int ret;
115
116         if (!sb->s_qcop->get_info)
117                 return -ENOSYS;
118         ret = sb->s_qcop->get_info(sb, type, &info);
119         if (!ret && copy_to_user(addr, &info, sizeof(info)))
120                 return -EFAULT;
121         return ret;
122 }
123
124 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
125 {
126         struct if_dqinfo info;
127
128         if (copy_from_user(&info, addr, sizeof(info)))
129                 return -EFAULT;
130         if (!sb->s_qcop->set_info)
131                 return -ENOSYS;
132         return sb->s_qcop->set_info(sb, type, &info);
133 }
134
135 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
136 {
137         dst->dqb_bhardlimit = src->d_blk_hardlimit;
138         dst->dqb_bsoftlimit = src->d_blk_softlimit;
139         dst->dqb_curspace = src->d_bcount;
140         dst->dqb_ihardlimit = src->d_ino_hardlimit;
141         dst->dqb_isoftlimit = src->d_ino_softlimit;
142         dst->dqb_curinodes = src->d_icount;
143         dst->dqb_btime = src->d_btimer;
144         dst->dqb_itime = src->d_itimer;
145         dst->dqb_valid = QIF_ALL;
146 }
147
148 static int quota_getquota(struct super_block *sb, int type, qid_t id,
149                           void __user *addr)
150 {
151         struct fs_disk_quota fdq;
152         struct if_dqblk idq;
153         int ret;
154
155         if (!sb->s_qcop->get_dqblk)
156                 return -ENOSYS;
157         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
158         if (ret)
159                 return ret;
160         copy_to_if_dqblk(&idq, &fdq);
161         if (copy_to_user(addr, &idq, sizeof(idq)))
162                 return -EFAULT;
163         return 0;
164 }
165
166 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
167 {
168         dst->d_blk_hardlimit = src->dqb_bhardlimit;
169         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
170         dst->d_bcount = src->dqb_curspace;
171         dst->d_ino_hardlimit = src->dqb_ihardlimit;
172         dst->d_ino_softlimit = src->dqb_isoftlimit;
173         dst->d_icount = src->dqb_curinodes;
174         dst->d_btimer = src->dqb_btime;
175         dst->d_itimer = src->dqb_itime;
176
177         dst->d_fieldmask = 0;
178         if (src->dqb_valid & QIF_BLIMITS)
179                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
180         if (src->dqb_valid & QIF_SPACE)
181                 dst->d_fieldmask |= FS_DQ_BCOUNT;
182         if (src->dqb_valid & QIF_ILIMITS)
183                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
184         if (src->dqb_valid & QIF_INODES)
185                 dst->d_fieldmask |= FS_DQ_ICOUNT;
186         if (src->dqb_valid & QIF_BTIME)
187                 dst->d_fieldmask |= FS_DQ_BTIMER;
188         if (src->dqb_valid & QIF_ITIME)
189                 dst->d_fieldmask |= FS_DQ_ITIMER;
190 }
191
192 static int quota_setquota(struct super_block *sb, int type, qid_t id,
193                           void __user *addr)
194 {
195         struct fs_disk_quota fdq;
196         struct if_dqblk idq;
197
198         if (copy_from_user(&idq, addr, sizeof(idq)))
199                 return -EFAULT;
200         if (!sb->s_qcop->set_dqblk)
201                 return -ENOSYS;
202         copy_from_if_dqblk(&fdq, &idq);
203         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
204 }
205
206 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
207 {
208         __u32 flags;
209
210         if (copy_from_user(&flags, addr, sizeof(flags)))
211                 return -EFAULT;
212         if (!sb->s_qcop->set_xstate)
213                 return -ENOSYS;
214         return sb->s_qcop->set_xstate(sb, flags, cmd);
215 }
216
217 static int quota_getxstate(struct super_block *sb, void __user *addr)
218 {
219         struct fs_quota_stat fqs;
220         int ret;
221
222         if (!sb->s_qcop->get_xstate)
223                 return -ENOSYS;
224         ret = sb->s_qcop->get_xstate(sb, &fqs);
225         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
226                 return -EFAULT;
227         return ret;
228 }
229
230 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
231                            void __user *addr)
232 {
233         struct fs_disk_quota fdq;
234
235         if (copy_from_user(&fdq, addr, sizeof(fdq)))
236                 return -EFAULT;
237         if (!sb->s_qcop->set_dqblk)
238                 return -ENOSYS;
239         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
240 }
241
242 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
243                            void __user *addr)
244 {
245         struct fs_disk_quota fdq;
246         int ret;
247
248         if (!sb->s_qcop->get_dqblk)
249                 return -ENOSYS;
250         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
251         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
252                 return -EFAULT;
253         return ret;
254 }
255
256 /* Copy parameters and call proper function */
257 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
258                        void __user *addr)
259 {
260         int ret;
261
262         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
263                 return -EINVAL;
264         if (!sb->s_qcop)
265                 return -ENOSYS;
266
267         ret = check_quotactl_permission(sb, type, cmd, id);
268         if (ret < 0)
269                 return ret;
270
271         switch (cmd) {
272         case Q_QUOTAON:
273                 return quota_quotaon(sb, type, cmd, id, addr);
274         case Q_QUOTAOFF:
275                 if (!sb->s_qcop->quota_off)
276                         return -ENOSYS;
277                 return sb->s_qcop->quota_off(sb, type, 0);
278         case Q_GETFMT:
279                 return quota_getfmt(sb, type, addr);
280         case Q_GETINFO:
281                 return quota_getinfo(sb, type, addr);
282         case Q_SETINFO:
283                 return quota_setinfo(sb, type, addr);
284         case Q_GETQUOTA:
285                 return quota_getquota(sb, type, id, addr);
286         case Q_SETQUOTA:
287                 return quota_setquota(sb, type, id, addr);
288         case Q_SYNC:
289                 if (!sb->s_qcop->quota_sync)
290                         return -ENOSYS;
291                 return sb->s_qcop->quota_sync(sb, type, 1);
292         case Q_XQUOTAON:
293         case Q_XQUOTAOFF:
294         case Q_XQUOTARM:
295                 return quota_setxstate(sb, cmd, addr);
296         case Q_XGETQSTAT:
297                 return quota_getxstate(sb, addr);
298         case Q_XSETQLIM:
299                 return quota_setxquota(sb, type, id, addr);
300         case Q_XGETQUOTA:
301                 return quota_getxquota(sb, type, id, addr);
302         case Q_XQUOTASYNC:
303                 /* caller already holds s_umount */
304                 if (sb->s_flags & MS_RDONLY)
305                         return -EROFS;
306                 writeback_inodes_sb(sb);
307                 return 0;
308         default:
309                 return -EINVAL;
310         }
311 }
312
313 /*
314  * look up a superblock on which quota ops will be performed
315  * - use the name of a block device to find the superblock thereon
316  */
317 static struct super_block *quotactl_block(const char __user *special)
318 {
319 #ifdef CONFIG_BLOCK
320         struct block_device *bdev;
321         struct super_block *sb;
322         char *tmp = getname(special);
323
324         if (IS_ERR(tmp))
325                 return ERR_CAST(tmp);
326         bdev = lookup_bdev(tmp);
327         putname(tmp);
328         if (IS_ERR(bdev))
329                 return ERR_CAST(bdev);
330         sb = get_super(bdev);
331         bdput(bdev);
332         if (!sb)
333                 return ERR_PTR(-ENODEV);
334
335         return sb;
336 #else
337         return ERR_PTR(-ENODEV);
338 #endif
339 }
340
341 /*
342  * This is the system call interface. This communicates with
343  * the user-level programs. Currently this only supports diskquota
344  * calls. Maybe we need to add the process quotas etc. in the future,
345  * but we probably should use rlimits for that.
346  */
347 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
348                 qid_t, id, void __user *, addr)
349 {
350         uint cmds, type;
351         struct super_block *sb = NULL;
352         int ret;
353
354         cmds = cmd >> SUBCMDSHIFT;
355         type = cmd & SUBCMDMASK;
356
357         /*
358          * As a special case Q_SYNC can be called without a specific device.
359          * It will iterate all superblocks that have quota enabled and call
360          * the sync action on each of them.
361          */
362         if (!special) {
363                 if (cmds == Q_SYNC)
364                         return quota_sync_all(type);
365                 return -ENODEV;
366         }
367
368         sb = quotactl_block(special);
369         if (IS_ERR(sb))
370                 return PTR_ERR(sb);
371
372         ret = do_quotactl(sb, type, cmds, id, addr);
373
374         drop_super(sb);
375         return ret;
376 }