SUNRPC: One more clean up for rpc_create_client_dir()
[linux-3.10.git] / net / sunrpc / rpc_pipe.c
1 /*
2  * net/sunrpc/rpc_pipe.c
3  *
4  * Userland/kernel interface for rpcauth_gss.
5  * Code shamelessly plagiarized from fs/nfsd/nfsctl.c
6  * and fs/sysfs/inode.c
7  *
8  * Copyright (c) 2002, Trond Myklebust <trond.myklebust@fys.uio.no>
9  *
10  */
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/string.h>
14 #include <linux/pagemap.h>
15 #include <linux/mount.h>
16 #include <linux/namei.h>
17 #include <linux/fsnotify.h>
18 #include <linux/kernel.h>
19
20 #include <asm/ioctls.h>
21 #include <linux/fs.h>
22 #include <linux/poll.h>
23 #include <linux/wait.h>
24 #include <linux/seq_file.h>
25
26 #include <linux/sunrpc/clnt.h>
27 #include <linux/workqueue.h>
28 #include <linux/sunrpc/rpc_pipe_fs.h>
29
30 static struct vfsmount *rpc_mount __read_mostly;
31 static int rpc_mount_count;
32
33 static struct file_system_type rpc_pipe_fs_type;
34
35
36 static struct kmem_cache *rpc_inode_cachep __read_mostly;
37
38 #define RPC_UPCALL_TIMEOUT (30*HZ)
39
40 static void rpc_purge_list(struct rpc_inode *rpci, struct list_head *head,
41                 void (*destroy_msg)(struct rpc_pipe_msg *), int err)
42 {
43         struct rpc_pipe_msg *msg;
44
45         if (list_empty(head))
46                 return;
47         do {
48                 msg = list_entry(head->next, struct rpc_pipe_msg, list);
49                 list_del(&msg->list);
50                 msg->errno = err;
51                 destroy_msg(msg);
52         } while (!list_empty(head));
53         wake_up(&rpci->waitq);
54 }
55
56 static void
57 rpc_timeout_upcall_queue(struct work_struct *work)
58 {
59         LIST_HEAD(free_list);
60         struct rpc_inode *rpci =
61                 container_of(work, struct rpc_inode, queue_timeout.work);
62         struct inode *inode = &rpci->vfs_inode;
63         void (*destroy_msg)(struct rpc_pipe_msg *);
64
65         spin_lock(&inode->i_lock);
66         if (rpci->ops == NULL) {
67                 spin_unlock(&inode->i_lock);
68                 return;
69         }
70         destroy_msg = rpci->ops->destroy_msg;
71         if (rpci->nreaders == 0) {
72                 list_splice_init(&rpci->pipe, &free_list);
73                 rpci->pipelen = 0;
74         }
75         spin_unlock(&inode->i_lock);
76         rpc_purge_list(rpci, &free_list, destroy_msg, -ETIMEDOUT);
77 }
78
79 /**
80  * rpc_queue_upcall
81  * @inode: inode of upcall pipe on which to queue given message
82  * @msg: message to queue
83  *
84  * Call with an @inode created by rpc_mkpipe() to queue an upcall.
85  * A userspace process may then later read the upcall by performing a
86  * read on an open file for this inode.  It is up to the caller to
87  * initialize the fields of @msg (other than @msg->list) appropriately.
88  */
89 int
90 rpc_queue_upcall(struct inode *inode, struct rpc_pipe_msg *msg)
91 {
92         struct rpc_inode *rpci = RPC_I(inode);
93         int res = -EPIPE;
94
95         spin_lock(&inode->i_lock);
96         if (rpci->ops == NULL)
97                 goto out;
98         if (rpci->nreaders) {
99                 list_add_tail(&msg->list, &rpci->pipe);
100                 rpci->pipelen += msg->len;
101                 res = 0;
102         } else if (rpci->flags & RPC_PIPE_WAIT_FOR_OPEN) {
103                 if (list_empty(&rpci->pipe))
104                         queue_delayed_work(rpciod_workqueue,
105                                         &rpci->queue_timeout,
106                                         RPC_UPCALL_TIMEOUT);
107                 list_add_tail(&msg->list, &rpci->pipe);
108                 rpci->pipelen += msg->len;
109                 res = 0;
110         }
111 out:
112         spin_unlock(&inode->i_lock);
113         wake_up(&rpci->waitq);
114         return res;
115 }
116 EXPORT_SYMBOL_GPL(rpc_queue_upcall);
117
118 static inline void
119 rpc_inode_setowner(struct inode *inode, void *private)
120 {
121         RPC_I(inode)->private = private;
122 }
123
124 static void
125 rpc_close_pipes(struct inode *inode)
126 {
127         struct rpc_inode *rpci = RPC_I(inode);
128         const struct rpc_pipe_ops *ops;
129         int need_release;
130
131         mutex_lock(&inode->i_mutex);
132         ops = rpci->ops;
133         if (ops != NULL) {
134                 LIST_HEAD(free_list);
135                 spin_lock(&inode->i_lock);
136                 need_release = rpci->nreaders != 0 || rpci->nwriters != 0;
137                 rpci->nreaders = 0;
138                 list_splice_init(&rpci->in_upcall, &free_list);
139                 list_splice_init(&rpci->pipe, &free_list);
140                 rpci->pipelen = 0;
141                 rpci->ops = NULL;
142                 spin_unlock(&inode->i_lock);
143                 rpc_purge_list(rpci, &free_list, ops->destroy_msg, -EPIPE);
144                 rpci->nwriters = 0;
145                 if (need_release && ops->release_pipe)
146                         ops->release_pipe(inode);
147                 cancel_delayed_work_sync(&rpci->queue_timeout);
148         }
149         rpc_inode_setowner(inode, NULL);
150         mutex_unlock(&inode->i_mutex);
151 }
152
153 static struct inode *
154 rpc_alloc_inode(struct super_block *sb)
155 {
156         struct rpc_inode *rpci;
157         rpci = (struct rpc_inode *)kmem_cache_alloc(rpc_inode_cachep, GFP_KERNEL);
158         if (!rpci)
159                 return NULL;
160         return &rpci->vfs_inode;
161 }
162
163 static void
164 rpc_destroy_inode(struct inode *inode)
165 {
166         kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
167 }
168
169 static int
170 rpc_pipe_open(struct inode *inode, struct file *filp)
171 {
172         struct rpc_inode *rpci = RPC_I(inode);
173         int first_open;
174         int res = -ENXIO;
175
176         mutex_lock(&inode->i_mutex);
177         if (rpci->ops == NULL)
178                 goto out;
179         first_open = rpci->nreaders == 0 && rpci->nwriters == 0;
180         if (first_open && rpci->ops->open_pipe) {
181                 res = rpci->ops->open_pipe(inode);
182                 if (res)
183                         goto out;
184         }
185         if (filp->f_mode & FMODE_READ)
186                 rpci->nreaders++;
187         if (filp->f_mode & FMODE_WRITE)
188                 rpci->nwriters++;
189         res = 0;
190 out:
191         mutex_unlock(&inode->i_mutex);
192         return res;
193 }
194
195 static int
196 rpc_pipe_release(struct inode *inode, struct file *filp)
197 {
198         struct rpc_inode *rpci = RPC_I(inode);
199         struct rpc_pipe_msg *msg;
200         int last_close;
201
202         mutex_lock(&inode->i_mutex);
203         if (rpci->ops == NULL)
204                 goto out;
205         msg = (struct rpc_pipe_msg *)filp->private_data;
206         if (msg != NULL) {
207                 spin_lock(&inode->i_lock);
208                 msg->errno = -EAGAIN;
209                 list_del(&msg->list);
210                 spin_unlock(&inode->i_lock);
211                 rpci->ops->destroy_msg(msg);
212         }
213         if (filp->f_mode & FMODE_WRITE)
214                 rpci->nwriters --;
215         if (filp->f_mode & FMODE_READ) {
216                 rpci->nreaders --;
217                 if (rpci->nreaders == 0) {
218                         LIST_HEAD(free_list);
219                         spin_lock(&inode->i_lock);
220                         list_splice_init(&rpci->pipe, &free_list);
221                         rpci->pipelen = 0;
222                         spin_unlock(&inode->i_lock);
223                         rpc_purge_list(rpci, &free_list,
224                                         rpci->ops->destroy_msg, -EAGAIN);
225                 }
226         }
227         last_close = rpci->nwriters == 0 && rpci->nreaders == 0;
228         if (last_close && rpci->ops->release_pipe)
229                 rpci->ops->release_pipe(inode);
230 out:
231         mutex_unlock(&inode->i_mutex);
232         return 0;
233 }
234
235 static ssize_t
236 rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
237 {
238         struct inode *inode = filp->f_path.dentry->d_inode;
239         struct rpc_inode *rpci = RPC_I(inode);
240         struct rpc_pipe_msg *msg;
241         int res = 0;
242
243         mutex_lock(&inode->i_mutex);
244         if (rpci->ops == NULL) {
245                 res = -EPIPE;
246                 goto out_unlock;
247         }
248         msg = filp->private_data;
249         if (msg == NULL) {
250                 spin_lock(&inode->i_lock);
251                 if (!list_empty(&rpci->pipe)) {
252                         msg = list_entry(rpci->pipe.next,
253                                         struct rpc_pipe_msg,
254                                         list);
255                         list_move(&msg->list, &rpci->in_upcall);
256                         rpci->pipelen -= msg->len;
257                         filp->private_data = msg;
258                         msg->copied = 0;
259                 }
260                 spin_unlock(&inode->i_lock);
261                 if (msg == NULL)
262                         goto out_unlock;
263         }
264         /* NOTE: it is up to the callback to update msg->copied */
265         res = rpci->ops->upcall(filp, msg, buf, len);
266         if (res < 0 || msg->len == msg->copied) {
267                 filp->private_data = NULL;
268                 spin_lock(&inode->i_lock);
269                 list_del(&msg->list);
270                 spin_unlock(&inode->i_lock);
271                 rpci->ops->destroy_msg(msg);
272         }
273 out_unlock:
274         mutex_unlock(&inode->i_mutex);
275         return res;
276 }
277
278 static ssize_t
279 rpc_pipe_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
280 {
281         struct inode *inode = filp->f_path.dentry->d_inode;
282         struct rpc_inode *rpci = RPC_I(inode);
283         int res;
284
285         mutex_lock(&inode->i_mutex);
286         res = -EPIPE;
287         if (rpci->ops != NULL)
288                 res = rpci->ops->downcall(filp, buf, len);
289         mutex_unlock(&inode->i_mutex);
290         return res;
291 }
292
293 static unsigned int
294 rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
295 {
296         struct rpc_inode *rpci;
297         unsigned int mask = 0;
298
299         rpci = RPC_I(filp->f_path.dentry->d_inode);
300         poll_wait(filp, &rpci->waitq, wait);
301
302         mask = POLLOUT | POLLWRNORM;
303         if (rpci->ops == NULL)
304                 mask |= POLLERR | POLLHUP;
305         if (filp->private_data || !list_empty(&rpci->pipe))
306                 mask |= POLLIN | POLLRDNORM;
307         return mask;
308 }
309
310 static int
311 rpc_pipe_ioctl(struct inode *ino, struct file *filp,
312                 unsigned int cmd, unsigned long arg)
313 {
314         struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
315         int len;
316
317         switch (cmd) {
318         case FIONREAD:
319                 if (rpci->ops == NULL)
320                         return -EPIPE;
321                 len = rpci->pipelen;
322                 if (filp->private_data) {
323                         struct rpc_pipe_msg *msg;
324                         msg = (struct rpc_pipe_msg *)filp->private_data;
325                         len += msg->len - msg->copied;
326                 }
327                 return put_user(len, (int __user *)arg);
328         default:
329                 return -EINVAL;
330         }
331 }
332
333 static const struct file_operations rpc_pipe_fops = {
334         .owner          = THIS_MODULE,
335         .llseek         = no_llseek,
336         .read           = rpc_pipe_read,
337         .write          = rpc_pipe_write,
338         .poll           = rpc_pipe_poll,
339         .ioctl          = rpc_pipe_ioctl,
340         .open           = rpc_pipe_open,
341         .release        = rpc_pipe_release,
342 };
343
344 static int
345 rpc_show_info(struct seq_file *m, void *v)
346 {
347         struct rpc_clnt *clnt = m->private;
348
349         seq_printf(m, "RPC server: %s\n", clnt->cl_server);
350         seq_printf(m, "service: %s (%d) version %d\n", clnt->cl_protname,
351                         clnt->cl_prog, clnt->cl_vers);
352         seq_printf(m, "address: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_ADDR));
353         seq_printf(m, "protocol: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PROTO));
354         seq_printf(m, "port: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PORT));
355         return 0;
356 }
357
358 static int
359 rpc_info_open(struct inode *inode, struct file *file)
360 {
361         struct rpc_clnt *clnt;
362         int ret = single_open(file, rpc_show_info, NULL);
363
364         if (!ret) {
365                 struct seq_file *m = file->private_data;
366                 mutex_lock(&inode->i_mutex);
367                 clnt = RPC_I(inode)->private;
368                 if (clnt) {
369                         kref_get(&clnt->cl_kref);
370                         m->private = clnt;
371                 } else {
372                         single_release(inode, file);
373                         ret = -EINVAL;
374                 }
375                 mutex_unlock(&inode->i_mutex);
376         }
377         return ret;
378 }
379
380 static int
381 rpc_info_release(struct inode *inode, struct file *file)
382 {
383         struct seq_file *m = file->private_data;
384         struct rpc_clnt *clnt = (struct rpc_clnt *)m->private;
385
386         if (clnt)
387                 rpc_release_client(clnt);
388         return single_release(inode, file);
389 }
390
391 static const struct file_operations rpc_info_operations = {
392         .owner          = THIS_MODULE,
393         .open           = rpc_info_open,
394         .read           = seq_read,
395         .llseek         = seq_lseek,
396         .release        = rpc_info_release,
397 };
398
399
400 /*
401  * Description of fs contents.
402  */
403 struct rpc_filelist {
404         const char *name;
405         const struct file_operations *i_fop;
406         umode_t mode;
407 };
408
409 struct vfsmount *rpc_get_mount(void)
410 {
411         int err;
412
413         err = simple_pin_fs(&rpc_pipe_fs_type, &rpc_mount, &rpc_mount_count);
414         if (err != 0)
415                 return ERR_PTR(err);
416         return rpc_mount;
417 }
418
419 void rpc_put_mount(void)
420 {
421         simple_release_fs(&rpc_mount, &rpc_mount_count);
422 }
423
424 static int rpc_delete_dentry(struct dentry *dentry)
425 {
426         return 1;
427 }
428
429 static const struct dentry_operations rpc_dentry_operations = {
430         .d_delete = rpc_delete_dentry,
431 };
432
433 static struct inode *
434 rpc_get_inode(struct super_block *sb, umode_t mode)
435 {
436         struct inode *inode = new_inode(sb);
437         if (!inode)
438                 return NULL;
439         inode->i_mode = mode;
440         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
441         switch(mode & S_IFMT) {
442                 case S_IFDIR:
443                         inode->i_fop = &simple_dir_operations;
444                         inode->i_op = &simple_dir_inode_operations;
445                         inc_nlink(inode);
446                 default:
447                         break;
448         }
449         return inode;
450 }
451
452 static int __rpc_create_common(struct inode *dir, struct dentry *dentry,
453                                umode_t mode,
454                                const struct file_operations *i_fop,
455                                void *private)
456 {
457         struct inode *inode;
458
459         BUG_ON(!d_unhashed(dentry));
460         inode = rpc_get_inode(dir->i_sb, mode);
461         if (!inode)
462                 goto out_err;
463         inode->i_ino = iunique(dir->i_sb, 100);
464         if (i_fop)
465                 inode->i_fop = i_fop;
466         if (private)
467                 rpc_inode_setowner(inode, private);
468         d_add(dentry, inode);
469         return 0;
470 out_err:
471         printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %s\n",
472                         __FILE__, __func__, dentry->d_name.name);
473         dput(dentry);
474         return -ENOMEM;
475 }
476
477 static int __rpc_create(struct inode *dir, struct dentry *dentry,
478                         umode_t mode,
479                         const struct file_operations *i_fop,
480                         void *private)
481 {
482         int err;
483
484         err = __rpc_create_common(dir, dentry, S_IFREG | mode, i_fop, private);
485         if (err)
486                 return err;
487         fsnotify_create(dir, dentry);
488         return 0;
489 }
490
491 static int __rpc_mkdir(struct inode *dir, struct dentry *dentry,
492                        umode_t mode,
493                        const struct file_operations *i_fop,
494                        void *private)
495 {
496         int err;
497
498         err = __rpc_create_common(dir, dentry, S_IFDIR | mode, i_fop, private);
499         if (err)
500                 return err;
501         inc_nlink(dir);
502         fsnotify_mkdir(dir, dentry);
503         return 0;
504 }
505
506 static int __rpc_mkpipe(struct inode *dir, struct dentry *dentry,
507                         umode_t mode,
508                         const struct file_operations *i_fop,
509                         void *private,
510                         const struct rpc_pipe_ops *ops,
511                         int flags)
512 {
513         struct rpc_inode *rpci;
514         int err;
515
516         err = __rpc_create_common(dir, dentry, S_IFIFO | mode, i_fop, private);
517         if (err)
518                 return err;
519         rpci = RPC_I(dentry->d_inode);
520         rpci->nkern_readwriters = 1;
521         rpci->private = private;
522         rpci->flags = flags;
523         rpci->ops = ops;
524         fsnotify_create(dir, dentry);
525         return 0;
526 }
527
528 static int __rpc_rmdir(struct inode *dir, struct dentry *dentry)
529 {
530         int ret;
531
532         dget(dentry);
533         ret = simple_rmdir(dir, dentry);
534         d_delete(dentry);
535         dput(dentry);
536         return ret;
537 }
538
539 static int __rpc_unlink(struct inode *dir, struct dentry *dentry)
540 {
541         int ret;
542
543         dget(dentry);
544         ret = simple_unlink(dir, dentry);
545         d_delete(dentry);
546         dput(dentry);
547         return ret;
548 }
549
550 static int __rpc_rmpipe(struct inode *dir, struct dentry *dentry)
551 {
552         struct inode *inode = dentry->d_inode;
553         struct rpc_inode *rpci = RPC_I(inode);
554
555         rpci->nkern_readwriters--;
556         if (rpci->nkern_readwriters != 0)
557                 return 0;
558         rpc_close_pipes(inode);
559         return __rpc_unlink(dir, dentry);
560 }
561
562 static struct dentry *__rpc_lookup_create(struct dentry *parent,
563                                           struct qstr *name)
564 {
565         struct dentry *dentry;
566
567         dentry = d_lookup(parent, name);
568         if (!dentry) {
569                 dentry = d_alloc(parent, name);
570                 if (!dentry) {
571                         dentry = ERR_PTR(-ENOMEM);
572                         goto out_err;
573                 }
574         }
575         if (!dentry->d_inode)
576                 dentry->d_op = &rpc_dentry_operations;
577 out_err:
578         return dentry;
579 }
580
581 static struct dentry *__rpc_lookup_create_exclusive(struct dentry *parent,
582                                           struct qstr *name)
583 {
584         struct dentry *dentry;
585
586         dentry = __rpc_lookup_create(parent, name);
587         if (dentry->d_inode == NULL)
588                 return dentry;
589         dput(dentry);
590         return ERR_PTR(-EEXIST);
591 }
592
593 /*
594  * FIXME: This probably has races.
595  */
596 static void __rpc_depopulate(struct dentry *parent,
597                              const struct rpc_filelist *files,
598                              int start, int eof)
599 {
600         struct inode *dir = parent->d_inode;
601         struct dentry *dentry;
602         struct qstr name;
603         int i;
604
605         for (i = start; i < eof; i++) {
606                 name.name = files[i].name;
607                 name.len = strlen(files[i].name);
608                 name.hash = full_name_hash(name.name, name.len);
609                 dentry = d_lookup(parent, &name);
610
611                 if (dentry == NULL)
612                         continue;
613                 if (dentry->d_inode == NULL)
614                         goto next;
615                 switch (dentry->d_inode->i_mode & S_IFMT) {
616                         default:
617                                 BUG();
618                         case S_IFREG:
619                                 __rpc_unlink(dir, dentry);
620                                 break;
621                         case S_IFDIR:
622                                 __rpc_rmdir(dir, dentry);
623                 }
624 next:
625                 dput(dentry);
626         }
627 }
628
629 static void rpc_depopulate(struct dentry *parent,
630                            const struct rpc_filelist *files,
631                            int start, int eof)
632 {
633         struct inode *dir = parent->d_inode;
634
635         mutex_lock_nested(&dir->i_mutex, I_MUTEX_CHILD);
636         __rpc_depopulate(parent, files, start, eof);
637         mutex_unlock(&dir->i_mutex);
638 }
639
640 static int rpc_populate(struct dentry *parent,
641                         const struct rpc_filelist *files,
642                         int start, int eof,
643                         void *private)
644 {
645         struct inode *dir = parent->d_inode;
646         struct dentry *dentry;
647         int i, err;
648
649         mutex_lock(&dir->i_mutex);
650         for (i = start; i < eof; i++) {
651                 struct qstr q;
652
653                 q.name = files[i].name;
654                 q.len = strlen(files[i].name);
655                 q.hash = full_name_hash(q.name, q.len);
656                 dentry = __rpc_lookup_create_exclusive(parent, &q);
657                 err = PTR_ERR(dentry);
658                 if (IS_ERR(dentry))
659                         goto out_bad;
660                 switch (files[i].mode & S_IFMT) {
661                         default:
662                                 BUG();
663                         case S_IFREG:
664                                 err = __rpc_create(dir, dentry,
665                                                 files[i].mode,
666                                                 files[i].i_fop,
667                                                 private);
668                                 break;
669                         case S_IFDIR:
670                                 err = __rpc_mkdir(dir, dentry,
671                                                 files[i].mode,
672                                                 NULL,
673                                                 private);
674                 }
675                 if (err != 0)
676                         goto out_bad;
677         }
678         mutex_unlock(&dir->i_mutex);
679         return 0;
680 out_bad:
681         __rpc_depopulate(parent, files, start, eof);
682         mutex_unlock(&dir->i_mutex);
683         printk(KERN_WARNING "%s: %s failed to populate directory %s\n",
684                         __FILE__, __func__, parent->d_name.name);
685         return err;
686 }
687
688 static struct dentry *rpc_mkdir_populate(struct dentry *parent,
689                 struct qstr *name, umode_t mode, void *private,
690                 int (*populate)(struct dentry *, void *), void *args_populate)
691 {
692         struct dentry *dentry;
693         struct inode *dir = parent->d_inode;
694         int error;
695
696         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
697         dentry = __rpc_lookup_create_exclusive(parent, name);
698         if (IS_ERR(dentry))
699                 goto out;
700         error = __rpc_mkdir(dir, dentry, mode, NULL, private);
701         if (error != 0)
702                 goto out_err;
703         if (populate != NULL) {
704                 error = populate(dentry, args_populate);
705                 if (error)
706                         goto err_rmdir;
707         }
708 out:
709         mutex_unlock(&dir->i_mutex);
710         return dentry;
711 err_rmdir:
712         __rpc_rmdir(dir, dentry);
713 out_err:
714         dentry = ERR_PTR(error);
715         goto out;
716 }
717
718 static int rpc_rmdir_depopulate(struct dentry *dentry,
719                 void (*depopulate)(struct dentry *))
720 {
721         struct dentry *parent;
722         struct inode *dir;
723         int error;
724
725         parent = dget_parent(dentry);
726         dir = parent->d_inode;
727         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
728         if (depopulate != NULL)
729                 depopulate(dentry);
730         error = __rpc_rmdir(dir, dentry);
731         mutex_unlock(&dir->i_mutex);
732         dput(parent);
733         return error;
734 }
735
736 /**
737  * rpc_mkpipe - make an rpc_pipefs file for kernel<->userspace communication
738  * @parent: dentry of directory to create new "pipe" in
739  * @name: name of pipe
740  * @private: private data to associate with the pipe, for the caller's use
741  * @ops: operations defining the behavior of the pipe: upcall, downcall,
742  *      release_pipe, open_pipe, and destroy_msg.
743  * @flags: rpc_inode flags
744  *
745  * Data is made available for userspace to read by calls to
746  * rpc_queue_upcall().  The actual reads will result in calls to
747  * @ops->upcall, which will be called with the file pointer,
748  * message, and userspace buffer to copy to.
749  *
750  * Writes can come at any time, and do not necessarily have to be
751  * responses to upcalls.  They will result in calls to @msg->downcall.
752  *
753  * The @private argument passed here will be available to all these methods
754  * from the file pointer, via RPC_I(file->f_dentry->d_inode)->private.
755  */
756 struct dentry *rpc_mkpipe(struct dentry *parent, const char *name,
757                           void *private, const struct rpc_pipe_ops *ops,
758                           int flags)
759 {
760         struct dentry *dentry;
761         struct inode *dir = parent->d_inode;
762         umode_t umode = S_IFIFO | S_IRUSR | S_IWUSR;
763         struct qstr q;
764         int err;
765
766         if (ops->upcall == NULL)
767                 umode &= ~S_IRUGO;
768         if (ops->downcall == NULL)
769                 umode &= ~S_IWUGO;
770
771         q.name = name;
772         q.len = strlen(name);
773         q.hash = full_name_hash(q.name, q.len),
774
775         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
776         dentry = __rpc_lookup_create(parent, &q);
777         if (IS_ERR(dentry))
778                 goto out;
779         if (dentry->d_inode) {
780                 struct rpc_inode *rpci = RPC_I(dentry->d_inode);
781                 if (rpci->private != private ||
782                                 rpci->ops != ops ||
783                                 rpci->flags != flags) {
784                         dput (dentry);
785                         err = -EBUSY;
786                         goto out_err;
787                 }
788                 rpci->nkern_readwriters++;
789                 goto out;
790         }
791
792         err = __rpc_mkpipe(dir, dentry, umode, &rpc_pipe_fops,
793                            private, ops, flags);
794         if (err)
795                 goto out_err;
796 out:
797         mutex_unlock(&dir->i_mutex);
798         return dentry;
799 out_err:
800         dentry = ERR_PTR(err);
801         printk(KERN_WARNING "%s: %s() failed to create pipe %s/%s (errno = %d)\n",
802                         __FILE__, __func__, parent->d_name.name, name,
803                         err);
804         goto out;
805 }
806 EXPORT_SYMBOL_GPL(rpc_mkpipe);
807
808 /**
809  * rpc_unlink - remove a pipe
810  * @dentry: dentry for the pipe, as returned from rpc_mkpipe
811  *
812  * After this call, lookups will no longer find the pipe, and any
813  * attempts to read or write using preexisting opens of the pipe will
814  * return -EPIPE.
815  */
816 int
817 rpc_unlink(struct dentry *dentry)
818 {
819         struct dentry *parent;
820         struct inode *dir;
821         int error = 0;
822
823         parent = dget_parent(dentry);
824         dir = parent->d_inode;
825         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
826         error = __rpc_rmpipe(dir, dentry);
827         mutex_unlock(&dir->i_mutex);
828         dput(parent);
829         return error;
830 }
831 EXPORT_SYMBOL_GPL(rpc_unlink);
832
833 enum {
834         RPCAUTH_info,
835         RPCAUTH_EOF
836 };
837
838 static const struct rpc_filelist authfiles[] = {
839         [RPCAUTH_info] = {
840                 .name = "info",
841                 .i_fop = &rpc_info_operations,
842                 .mode = S_IFREG | S_IRUSR,
843         },
844 };
845
846 static int rpc_clntdir_populate(struct dentry *dentry, void *private)
847 {
848         return rpc_populate(dentry,
849                             authfiles, RPCAUTH_info, RPCAUTH_EOF,
850                             private);
851 }
852
853 static void rpc_clntdir_depopulate(struct dentry *dentry)
854 {
855         rpc_depopulate(dentry, authfiles, RPCAUTH_info, RPCAUTH_EOF);
856 }
857
858 /**
859  * rpc_create_client_dir - Create a new rpc_client directory in rpc_pipefs
860  * @path: path from the rpc_pipefs root to the new directory
861  * @rpc_client: rpc client to associate with this directory
862  *
863  * This creates a directory at the given @path associated with
864  * @rpc_clnt, which will contain a file named "info" with some basic
865  * information about the client, together with any "pipes" that may
866  * later be created using rpc_mkpipe().
867  */
868 struct dentry *rpc_create_client_dir(struct dentry *dentry,
869                                    struct qstr *name,
870                                    struct rpc_clnt *rpc_client)
871 {
872         return rpc_mkdir_populate(dentry, name, S_IRUGO | S_IXUGO, NULL,
873                         rpc_clntdir_populate, rpc_client);
874 }
875
876 /**
877  * rpc_remove_client_dir - Remove a directory created with rpc_create_client_dir()
878  * @dentry: directory to remove
879  */
880 int rpc_remove_client_dir(struct dentry *dentry)
881 {
882         return rpc_rmdir_depopulate(dentry, rpc_clntdir_depopulate);
883 }
884
885 /*
886  * populate the filesystem
887  */
888 static struct super_operations s_ops = {
889         .alloc_inode    = rpc_alloc_inode,
890         .destroy_inode  = rpc_destroy_inode,
891         .statfs         = simple_statfs,
892 };
893
894 #define RPCAUTH_GSSMAGIC 0x67596969
895
896 /*
897  * We have a single directory with 1 node in it.
898  */
899 enum {
900         RPCAUTH_lockd,
901         RPCAUTH_mount,
902         RPCAUTH_nfs,
903         RPCAUTH_portmap,
904         RPCAUTH_statd,
905         RPCAUTH_nfsd4_cb,
906         RPCAUTH_RootEOF
907 };
908
909 static const struct rpc_filelist files[] = {
910         [RPCAUTH_lockd] = {
911                 .name = "lockd",
912                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
913         },
914         [RPCAUTH_mount] = {
915                 .name = "mount",
916                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
917         },
918         [RPCAUTH_nfs] = {
919                 .name = "nfs",
920                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
921         },
922         [RPCAUTH_portmap] = {
923                 .name = "portmap",
924                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
925         },
926         [RPCAUTH_statd] = {
927                 .name = "statd",
928                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
929         },
930         [RPCAUTH_nfsd4_cb] = {
931                 .name = "nfsd4_cb",
932                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
933         },
934 };
935
936 static int
937 rpc_fill_super(struct super_block *sb, void *data, int silent)
938 {
939         struct inode *inode;
940         struct dentry *root;
941
942         sb->s_blocksize = PAGE_CACHE_SIZE;
943         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
944         sb->s_magic = RPCAUTH_GSSMAGIC;
945         sb->s_op = &s_ops;
946         sb->s_time_gran = 1;
947
948         inode = rpc_get_inode(sb, S_IFDIR | 0755);
949         if (!inode)
950                 return -ENOMEM;
951         root = d_alloc_root(inode);
952         if (!root) {
953                 iput(inode);
954                 return -ENOMEM;
955         }
956         if (rpc_populate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF, NULL))
957                 goto out;
958         sb->s_root = root;
959         return 0;
960 out:
961         d_genocide(root);
962         dput(root);
963         return -ENOMEM;
964 }
965
966 static int
967 rpc_get_sb(struct file_system_type *fs_type,
968                 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
969 {
970         return get_sb_single(fs_type, flags, data, rpc_fill_super, mnt);
971 }
972
973 static struct file_system_type rpc_pipe_fs_type = {
974         .owner          = THIS_MODULE,
975         .name           = "rpc_pipefs",
976         .get_sb         = rpc_get_sb,
977         .kill_sb        = kill_litter_super,
978 };
979
980 static void
981 init_once(void *foo)
982 {
983         struct rpc_inode *rpci = (struct rpc_inode *) foo;
984
985         inode_init_once(&rpci->vfs_inode);
986         rpci->private = NULL;
987         rpci->nreaders = 0;
988         rpci->nwriters = 0;
989         INIT_LIST_HEAD(&rpci->in_upcall);
990         INIT_LIST_HEAD(&rpci->in_downcall);
991         INIT_LIST_HEAD(&rpci->pipe);
992         rpci->pipelen = 0;
993         init_waitqueue_head(&rpci->waitq);
994         INIT_DELAYED_WORK(&rpci->queue_timeout,
995                             rpc_timeout_upcall_queue);
996         rpci->ops = NULL;
997 }
998
999 int register_rpc_pipefs(void)
1000 {
1001         int err;
1002
1003         rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",
1004                                 sizeof(struct rpc_inode),
1005                                 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
1006                                                 SLAB_MEM_SPREAD),
1007                                 init_once);
1008         if (!rpc_inode_cachep)
1009                 return -ENOMEM;
1010         err = register_filesystem(&rpc_pipe_fs_type);
1011         if (err) {
1012                 kmem_cache_destroy(rpc_inode_cachep);
1013                 return err;
1014         }
1015
1016         return 0;
1017 }
1018
1019 void unregister_rpc_pipefs(void)
1020 {
1021         kmem_cache_destroy(rpc_inode_cachep);
1022         unregister_filesystem(&rpc_pipe_fs_type);
1023 }