xref: /linux/net/sunrpc/rpc_pipe.c (revision 9ce7677cfd7cd871adb457c80bea3b581b839641)
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/config.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/string.h>
15 #include <linux/pagemap.h>
16 #include <linux/mount.h>
17 #include <linux/namei.h>
18 #include <linux/dnotify.h>
19 #include <linux/kernel.h>
20 
21 #include <asm/ioctls.h>
22 #include <linux/fs.h>
23 #include <linux/poll.h>
24 #include <linux/wait.h>
25 #include <linux/seq_file.h>
26 
27 #include <linux/sunrpc/clnt.h>
28 #include <linux/workqueue.h>
29 #include <linux/sunrpc/rpc_pipe_fs.h>
30 
31 static struct vfsmount *rpc_mount __read_mostly;
32 static int rpc_mount_count;
33 
34 static struct file_system_type rpc_pipe_fs_type;
35 
36 
37 static kmem_cache_t *rpc_inode_cachep __read_mostly;
38 
39 #define RPC_UPCALL_TIMEOUT (30*HZ)
40 
41 static void
42 __rpc_purge_list(struct rpc_inode *rpci, struct list_head *head, int err)
43 {
44 	struct rpc_pipe_msg *msg;
45 	void (*destroy_msg)(struct rpc_pipe_msg *);
46 
47 	destroy_msg = rpci->ops->destroy_msg;
48 	while (!list_empty(head)) {
49 		msg = list_entry(head->next, struct rpc_pipe_msg, list);
50 		list_del_init(&msg->list);
51 		msg->errno = err;
52 		destroy_msg(msg);
53 	}
54 }
55 
56 static void
57 __rpc_purge_upcall(struct inode *inode, int err)
58 {
59 	struct rpc_inode *rpci = RPC_I(inode);
60 
61 	__rpc_purge_list(rpci, &rpci->pipe, err);
62 	rpci->pipelen = 0;
63 	wake_up(&rpci->waitq);
64 }
65 
66 static void
67 rpc_timeout_upcall_queue(void *data)
68 {
69 	struct rpc_inode *rpci = (struct rpc_inode *)data;
70 	struct inode *inode = &rpci->vfs_inode;
71 
72 	down(&inode->i_sem);
73 	if (rpci->nreaders == 0 && !list_empty(&rpci->pipe))
74 		__rpc_purge_upcall(inode, -ETIMEDOUT);
75 	up(&inode->i_sem);
76 }
77 
78 int
79 rpc_queue_upcall(struct inode *inode, struct rpc_pipe_msg *msg)
80 {
81 	struct rpc_inode *rpci = RPC_I(inode);
82 	int res = -EPIPE;
83 
84 	down(&inode->i_sem);
85 	if (rpci->ops == NULL)
86 		goto out;
87 	if (rpci->nreaders) {
88 		list_add_tail(&msg->list, &rpci->pipe);
89 		rpci->pipelen += msg->len;
90 		res = 0;
91 	} else if (rpci->flags & RPC_PIPE_WAIT_FOR_OPEN) {
92 		if (list_empty(&rpci->pipe))
93 			schedule_delayed_work(&rpci->queue_timeout,
94 					RPC_UPCALL_TIMEOUT);
95 		list_add_tail(&msg->list, &rpci->pipe);
96 		rpci->pipelen += msg->len;
97 		res = 0;
98 	}
99 out:
100 	up(&inode->i_sem);
101 	wake_up(&rpci->waitq);
102 	return res;
103 }
104 
105 static inline void
106 rpc_inode_setowner(struct inode *inode, void *private)
107 {
108 	RPC_I(inode)->private = private;
109 }
110 
111 static void
112 rpc_close_pipes(struct inode *inode)
113 {
114 	struct rpc_inode *rpci = RPC_I(inode);
115 
116 	cancel_delayed_work(&rpci->queue_timeout);
117 	flush_scheduled_work();
118 	down(&inode->i_sem);
119 	if (rpci->ops != NULL) {
120 		rpci->nreaders = 0;
121 		__rpc_purge_list(rpci, &rpci->in_upcall, -EPIPE);
122 		__rpc_purge_upcall(inode, -EPIPE);
123 		rpci->nwriters = 0;
124 		if (rpci->ops->release_pipe)
125 			rpci->ops->release_pipe(inode);
126 		rpci->ops = NULL;
127 	}
128 	rpc_inode_setowner(inode, NULL);
129 	up(&inode->i_sem);
130 }
131 
132 static struct inode *
133 rpc_alloc_inode(struct super_block *sb)
134 {
135 	struct rpc_inode *rpci;
136 	rpci = (struct rpc_inode *)kmem_cache_alloc(rpc_inode_cachep, SLAB_KERNEL);
137 	if (!rpci)
138 		return NULL;
139 	return &rpci->vfs_inode;
140 }
141 
142 static void
143 rpc_destroy_inode(struct inode *inode)
144 {
145 	kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
146 }
147 
148 static int
149 rpc_pipe_open(struct inode *inode, struct file *filp)
150 {
151 	struct rpc_inode *rpci = RPC_I(inode);
152 	int res = -ENXIO;
153 
154 	down(&inode->i_sem);
155 	if (rpci->ops != NULL) {
156 		if (filp->f_mode & FMODE_READ)
157 			rpci->nreaders ++;
158 		if (filp->f_mode & FMODE_WRITE)
159 			rpci->nwriters ++;
160 		res = 0;
161 	}
162 	up(&inode->i_sem);
163 	return res;
164 }
165 
166 static int
167 rpc_pipe_release(struct inode *inode, struct file *filp)
168 {
169 	struct rpc_inode *rpci = RPC_I(filp->f_dentry->d_inode);
170 	struct rpc_pipe_msg *msg;
171 
172 	down(&inode->i_sem);
173 	if (rpci->ops == NULL)
174 		goto out;
175 	msg = (struct rpc_pipe_msg *)filp->private_data;
176 	if (msg != NULL) {
177 		msg->errno = -EPIPE;
178 		list_del_init(&msg->list);
179 		rpci->ops->destroy_msg(msg);
180 	}
181 	if (filp->f_mode & FMODE_WRITE)
182 		rpci->nwriters --;
183 	if (filp->f_mode & FMODE_READ)
184 		rpci->nreaders --;
185 	if (!rpci->nreaders)
186 		__rpc_purge_upcall(inode, -EPIPE);
187 	if (rpci->ops->release_pipe)
188 		rpci->ops->release_pipe(inode);
189 out:
190 	up(&inode->i_sem);
191 	return 0;
192 }
193 
194 static ssize_t
195 rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
196 {
197 	struct inode *inode = filp->f_dentry->d_inode;
198 	struct rpc_inode *rpci = RPC_I(inode);
199 	struct rpc_pipe_msg *msg;
200 	int res = 0;
201 
202 	down(&inode->i_sem);
203 	if (rpci->ops == NULL) {
204 		res = -EPIPE;
205 		goto out_unlock;
206 	}
207 	msg = filp->private_data;
208 	if (msg == NULL) {
209 		if (!list_empty(&rpci->pipe)) {
210 			msg = list_entry(rpci->pipe.next,
211 					struct rpc_pipe_msg,
212 					list);
213 			list_move(&msg->list, &rpci->in_upcall);
214 			rpci->pipelen -= msg->len;
215 			filp->private_data = msg;
216 			msg->copied = 0;
217 		}
218 		if (msg == NULL)
219 			goto out_unlock;
220 	}
221 	/* NOTE: it is up to the callback to update msg->copied */
222 	res = rpci->ops->upcall(filp, msg, buf, len);
223 	if (res < 0 || msg->len == msg->copied) {
224 		filp->private_data = NULL;
225 		list_del_init(&msg->list);
226 		rpci->ops->destroy_msg(msg);
227 	}
228 out_unlock:
229 	up(&inode->i_sem);
230 	return res;
231 }
232 
233 static ssize_t
234 rpc_pipe_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
235 {
236 	struct inode *inode = filp->f_dentry->d_inode;
237 	struct rpc_inode *rpci = RPC_I(inode);
238 	int res;
239 
240 	down(&inode->i_sem);
241 	res = -EPIPE;
242 	if (rpci->ops != NULL)
243 		res = rpci->ops->downcall(filp, buf, len);
244 	up(&inode->i_sem);
245 	return res;
246 }
247 
248 static unsigned int
249 rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
250 {
251 	struct rpc_inode *rpci;
252 	unsigned int mask = 0;
253 
254 	rpci = RPC_I(filp->f_dentry->d_inode);
255 	poll_wait(filp, &rpci->waitq, wait);
256 
257 	mask = POLLOUT | POLLWRNORM;
258 	if (rpci->ops == NULL)
259 		mask |= POLLERR | POLLHUP;
260 	if (!list_empty(&rpci->pipe))
261 		mask |= POLLIN | POLLRDNORM;
262 	return mask;
263 }
264 
265 static int
266 rpc_pipe_ioctl(struct inode *ino, struct file *filp,
267 		unsigned int cmd, unsigned long arg)
268 {
269 	struct rpc_inode *rpci = RPC_I(filp->f_dentry->d_inode);
270 	int len;
271 
272 	switch (cmd) {
273 	case FIONREAD:
274 		if (rpci->ops == NULL)
275 			return -EPIPE;
276 		len = rpci->pipelen;
277 		if (filp->private_data) {
278 			struct rpc_pipe_msg *msg;
279 			msg = (struct rpc_pipe_msg *)filp->private_data;
280 			len += msg->len - msg->copied;
281 		}
282 		return put_user(len, (int __user *)arg);
283 	default:
284 		return -EINVAL;
285 	}
286 }
287 
288 static struct file_operations rpc_pipe_fops = {
289 	.owner		= THIS_MODULE,
290 	.llseek		= no_llseek,
291 	.read		= rpc_pipe_read,
292 	.write		= rpc_pipe_write,
293 	.poll		= rpc_pipe_poll,
294 	.ioctl		= rpc_pipe_ioctl,
295 	.open		= rpc_pipe_open,
296 	.release	= rpc_pipe_release,
297 };
298 
299 static int
300 rpc_show_info(struct seq_file *m, void *v)
301 {
302 	struct rpc_clnt *clnt = m->private;
303 
304 	seq_printf(m, "RPC server: %s\n", clnt->cl_server);
305 	seq_printf(m, "service: %s (%d) version %d\n", clnt->cl_protname,
306 			clnt->cl_prog, clnt->cl_vers);
307 	seq_printf(m, "address: %u.%u.%u.%u\n",
308 			NIPQUAD(clnt->cl_xprt->addr.sin_addr.s_addr));
309 	seq_printf(m, "protocol: %s\n",
310 			clnt->cl_xprt->prot == IPPROTO_UDP ? "udp" : "tcp");
311 	return 0;
312 }
313 
314 static int
315 rpc_info_open(struct inode *inode, struct file *file)
316 {
317 	struct rpc_clnt *clnt;
318 	int ret = single_open(file, rpc_show_info, NULL);
319 
320 	if (!ret) {
321 		struct seq_file *m = file->private_data;
322 		down(&inode->i_sem);
323 		clnt = RPC_I(inode)->private;
324 		if (clnt) {
325 			atomic_inc(&clnt->cl_users);
326 			m->private = clnt;
327 		} else {
328 			single_release(inode, file);
329 			ret = -EINVAL;
330 		}
331 		up(&inode->i_sem);
332 	}
333 	return ret;
334 }
335 
336 static int
337 rpc_info_release(struct inode *inode, struct file *file)
338 {
339 	struct seq_file *m = file->private_data;
340 	struct rpc_clnt *clnt = (struct rpc_clnt *)m->private;
341 
342 	if (clnt)
343 		rpc_release_client(clnt);
344 	return single_release(inode, file);
345 }
346 
347 static struct file_operations rpc_info_operations = {
348 	.owner		= THIS_MODULE,
349 	.open		= rpc_info_open,
350 	.read		= seq_read,
351 	.llseek		= seq_lseek,
352 	.release	= rpc_info_release,
353 };
354 
355 
356 /*
357  * We have a single directory with 1 node in it.
358  */
359 enum {
360 	RPCAUTH_Root = 1,
361 	RPCAUTH_lockd,
362 	RPCAUTH_mount,
363 	RPCAUTH_nfs,
364 	RPCAUTH_portmap,
365 	RPCAUTH_statd,
366 	RPCAUTH_RootEOF
367 };
368 
369 /*
370  * Description of fs contents.
371  */
372 struct rpc_filelist {
373 	char *name;
374 	struct file_operations *i_fop;
375 	int mode;
376 };
377 
378 static struct rpc_filelist files[] = {
379 	[RPCAUTH_lockd] = {
380 		.name = "lockd",
381 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
382 	},
383 	[RPCAUTH_mount] = {
384 		.name = "mount",
385 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
386 	},
387 	[RPCAUTH_nfs] = {
388 		.name = "nfs",
389 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
390 	},
391 	[RPCAUTH_portmap] = {
392 		.name = "portmap",
393 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
394 	},
395 	[RPCAUTH_statd] = {
396 		.name = "statd",
397 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
398 	},
399 };
400 
401 enum {
402 	RPCAUTH_info = 2,
403 	RPCAUTH_EOF
404 };
405 
406 static struct rpc_filelist authfiles[] = {
407 	[RPCAUTH_info] = {
408 		.name = "info",
409 		.i_fop = &rpc_info_operations,
410 		.mode = S_IFREG | S_IRUSR,
411 	},
412 };
413 
414 static int
415 rpc_get_mount(void)
416 {
417 	return simple_pin_fs("rpc_pipefs", &rpc_mount, &rpc_mount_count);
418 }
419 
420 static void
421 rpc_put_mount(void)
422 {
423 	simple_release_fs(&rpc_mount, &rpc_mount_count);
424 }
425 
426 static int
427 rpc_lookup_parent(char *path, struct nameidata *nd)
428 {
429 	if (path[0] == '\0')
430 		return -ENOENT;
431 	if (rpc_get_mount()) {
432 		printk(KERN_WARNING "%s: %s failed to mount "
433 			       "pseudofilesystem \n", __FILE__, __FUNCTION__);
434 		return -ENODEV;
435 	}
436 	nd->mnt = mntget(rpc_mount);
437 	nd->dentry = dget(rpc_mount->mnt_root);
438 	nd->last_type = LAST_ROOT;
439 	nd->flags = LOOKUP_PARENT;
440 	nd->depth = 0;
441 
442 	if (path_walk(path, nd)) {
443 		printk(KERN_WARNING "%s: %s failed to find path %s\n",
444 				__FILE__, __FUNCTION__, path);
445 		rpc_put_mount();
446 		return -ENOENT;
447 	}
448 	return 0;
449 }
450 
451 static void
452 rpc_release_path(struct nameidata *nd)
453 {
454 	path_release(nd);
455 	rpc_put_mount();
456 }
457 
458 static struct inode *
459 rpc_get_inode(struct super_block *sb, int mode)
460 {
461 	struct inode *inode = new_inode(sb);
462 	if (!inode)
463 		return NULL;
464 	inode->i_mode = mode;
465 	inode->i_uid = inode->i_gid = 0;
466 	inode->i_blksize = PAGE_CACHE_SIZE;
467 	inode->i_blocks = 0;
468 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
469 	switch(mode & S_IFMT) {
470 		case S_IFDIR:
471 			inode->i_fop = &simple_dir_operations;
472 			inode->i_op = &simple_dir_inode_operations;
473 			inode->i_nlink++;
474 		default:
475 			break;
476 	}
477 	return inode;
478 }
479 
480 /*
481  * FIXME: This probably has races.
482  */
483 static void
484 rpc_depopulate(struct dentry *parent)
485 {
486 	struct inode *dir = parent->d_inode;
487 	struct list_head *pos, *next;
488 	struct dentry *dentry, *dvec[10];
489 	int n = 0;
490 
491 	down(&dir->i_sem);
492 repeat:
493 	spin_lock(&dcache_lock);
494 	list_for_each_safe(pos, next, &parent->d_subdirs) {
495 		dentry = list_entry(pos, struct dentry, d_child);
496 		spin_lock(&dentry->d_lock);
497 		if (!d_unhashed(dentry)) {
498 			dget_locked(dentry);
499 			__d_drop(dentry);
500 			spin_unlock(&dentry->d_lock);
501 			dvec[n++] = dentry;
502 			if (n == ARRAY_SIZE(dvec))
503 				break;
504 		} else
505 			spin_unlock(&dentry->d_lock);
506 	}
507 	spin_unlock(&dcache_lock);
508 	if (n) {
509 		do {
510 			dentry = dvec[--n];
511 			if (dentry->d_inode) {
512 				rpc_close_pipes(dentry->d_inode);
513 				simple_unlink(dir, dentry);
514 			}
515 			dput(dentry);
516 		} while (n);
517 		goto repeat;
518 	}
519 	up(&dir->i_sem);
520 }
521 
522 static int
523 rpc_populate(struct dentry *parent,
524 		struct rpc_filelist *files,
525 		int start, int eof)
526 {
527 	struct inode *inode, *dir = parent->d_inode;
528 	void *private = RPC_I(dir)->private;
529 	struct dentry *dentry;
530 	int mode, i;
531 
532 	down(&dir->i_sem);
533 	for (i = start; i < eof; i++) {
534 		dentry = d_alloc_name(parent, files[i].name);
535 		if (!dentry)
536 			goto out_bad;
537 		mode = files[i].mode;
538 		inode = rpc_get_inode(dir->i_sb, mode);
539 		if (!inode) {
540 			dput(dentry);
541 			goto out_bad;
542 		}
543 		inode->i_ino = i;
544 		if (files[i].i_fop)
545 			inode->i_fop = files[i].i_fop;
546 		if (private)
547 			rpc_inode_setowner(inode, private);
548 		if (S_ISDIR(mode))
549 			dir->i_nlink++;
550 		d_add(dentry, inode);
551 	}
552 	up(&dir->i_sem);
553 	return 0;
554 out_bad:
555 	up(&dir->i_sem);
556 	printk(KERN_WARNING "%s: %s failed to populate directory %s\n",
557 			__FILE__, __FUNCTION__, parent->d_name.name);
558 	return -ENOMEM;
559 }
560 
561 static int
562 __rpc_mkdir(struct inode *dir, struct dentry *dentry)
563 {
564 	struct inode *inode;
565 
566 	inode = rpc_get_inode(dir->i_sb, S_IFDIR | S_IRUSR | S_IXUSR);
567 	if (!inode)
568 		goto out_err;
569 	inode->i_ino = iunique(dir->i_sb, 100);
570 	d_instantiate(dentry, inode);
571 	dir->i_nlink++;
572 	inode_dir_notify(dir, DN_CREATE);
573 	rpc_get_mount();
574 	return 0;
575 out_err:
576 	printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %s\n",
577 			__FILE__, __FUNCTION__, dentry->d_name.name);
578 	return -ENOMEM;
579 }
580 
581 static int
582 __rpc_rmdir(struct inode *dir, struct dentry *dentry)
583 {
584 	int error;
585 
586 	shrink_dcache_parent(dentry);
587 	if (dentry->d_inode)
588 		rpc_close_pipes(dentry->d_inode);
589 	if ((error = simple_rmdir(dir, dentry)) != 0)
590 		return error;
591 	if (!error) {
592 		inode_dir_notify(dir, DN_DELETE);
593 		d_drop(dentry);
594 		rpc_put_mount();
595 	}
596 	return 0;
597 }
598 
599 static struct dentry *
600 rpc_lookup_negative(char *path, struct nameidata *nd)
601 {
602 	struct dentry *dentry;
603 	struct inode *dir;
604 	int error;
605 
606 	if ((error = rpc_lookup_parent(path, nd)) != 0)
607 		return ERR_PTR(error);
608 	dir = nd->dentry->d_inode;
609 	down(&dir->i_sem);
610 	dentry = lookup_hash(nd);
611 	if (IS_ERR(dentry))
612 		goto out_err;
613 	if (dentry->d_inode) {
614 		dput(dentry);
615 		dentry = ERR_PTR(-EEXIST);
616 		goto out_err;
617 	}
618 	return dentry;
619 out_err:
620 	up(&dir->i_sem);
621 	rpc_release_path(nd);
622 	return dentry;
623 }
624 
625 
626 struct dentry *
627 rpc_mkdir(char *path, struct rpc_clnt *rpc_client)
628 {
629 	struct nameidata nd;
630 	struct dentry *dentry;
631 	struct inode *dir;
632 	int error;
633 
634 	dentry = rpc_lookup_negative(path, &nd);
635 	if (IS_ERR(dentry))
636 		return dentry;
637 	dir = nd.dentry->d_inode;
638 	if ((error = __rpc_mkdir(dir, dentry)) != 0)
639 		goto err_dput;
640 	RPC_I(dentry->d_inode)->private = rpc_client;
641 	error = rpc_populate(dentry, authfiles,
642 			RPCAUTH_info, RPCAUTH_EOF);
643 	if (error)
644 		goto err_depopulate;
645 out:
646 	up(&dir->i_sem);
647 	rpc_release_path(&nd);
648 	return dentry;
649 err_depopulate:
650 	rpc_depopulate(dentry);
651 	__rpc_rmdir(dir, dentry);
652 err_dput:
653 	dput(dentry);
654 	printk(KERN_WARNING "%s: %s() failed to create directory %s (errno = %d)\n",
655 			__FILE__, __FUNCTION__, path, error);
656 	dentry = ERR_PTR(error);
657 	goto out;
658 }
659 
660 int
661 rpc_rmdir(char *path)
662 {
663 	struct nameidata nd;
664 	struct dentry *dentry;
665 	struct inode *dir;
666 	int error;
667 
668 	if ((error = rpc_lookup_parent(path, &nd)) != 0)
669 		return error;
670 	dir = nd.dentry->d_inode;
671 	down(&dir->i_sem);
672 	dentry = lookup_hash(&nd);
673 	if (IS_ERR(dentry)) {
674 		error = PTR_ERR(dentry);
675 		goto out_release;
676 	}
677 	rpc_depopulate(dentry);
678 	error = __rpc_rmdir(dir, dentry);
679 	dput(dentry);
680 out_release:
681 	up(&dir->i_sem);
682 	rpc_release_path(&nd);
683 	return error;
684 }
685 
686 struct dentry *
687 rpc_mkpipe(char *path, void *private, struct rpc_pipe_ops *ops, int flags)
688 {
689 	struct nameidata nd;
690 	struct dentry *dentry;
691 	struct inode *dir, *inode;
692 	struct rpc_inode *rpci;
693 
694 	dentry = rpc_lookup_negative(path, &nd);
695 	if (IS_ERR(dentry))
696 		return dentry;
697 	dir = nd.dentry->d_inode;
698 	inode = rpc_get_inode(dir->i_sb, S_IFSOCK | S_IRUSR | S_IWUSR);
699 	if (!inode)
700 		goto err_dput;
701 	inode->i_ino = iunique(dir->i_sb, 100);
702 	inode->i_fop = &rpc_pipe_fops;
703 	d_instantiate(dentry, inode);
704 	rpci = RPC_I(inode);
705 	rpci->private = private;
706 	rpci->flags = flags;
707 	rpci->ops = ops;
708 	inode_dir_notify(dir, DN_CREATE);
709 out:
710 	up(&dir->i_sem);
711 	rpc_release_path(&nd);
712 	return dentry;
713 err_dput:
714 	dput(dentry);
715 	dentry = ERR_PTR(-ENOMEM);
716 	printk(KERN_WARNING "%s: %s() failed to create pipe %s (errno = %d)\n",
717 			__FILE__, __FUNCTION__, path, -ENOMEM);
718 	goto out;
719 }
720 
721 int
722 rpc_unlink(char *path)
723 {
724 	struct nameidata nd;
725 	struct dentry *dentry;
726 	struct inode *dir;
727 	int error;
728 
729 	if ((error = rpc_lookup_parent(path, &nd)) != 0)
730 		return error;
731 	dir = nd.dentry->d_inode;
732 	down(&dir->i_sem);
733 	dentry = lookup_hash(&nd);
734 	if (IS_ERR(dentry)) {
735 		error = PTR_ERR(dentry);
736 		goto out_release;
737 	}
738 	d_drop(dentry);
739 	if (dentry->d_inode) {
740 		rpc_close_pipes(dentry->d_inode);
741 		error = simple_unlink(dir, dentry);
742 	}
743 	dput(dentry);
744 	inode_dir_notify(dir, DN_DELETE);
745 out_release:
746 	up(&dir->i_sem);
747 	rpc_release_path(&nd);
748 	return error;
749 }
750 
751 /*
752  * populate the filesystem
753  */
754 static struct super_operations s_ops = {
755 	.alloc_inode	= rpc_alloc_inode,
756 	.destroy_inode	= rpc_destroy_inode,
757 	.statfs		= simple_statfs,
758 };
759 
760 #define RPCAUTH_GSSMAGIC 0x67596969
761 
762 static int
763 rpc_fill_super(struct super_block *sb, void *data, int silent)
764 {
765 	struct inode *inode;
766 	struct dentry *root;
767 
768 	sb->s_blocksize = PAGE_CACHE_SIZE;
769 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
770 	sb->s_magic = RPCAUTH_GSSMAGIC;
771 	sb->s_op = &s_ops;
772 	sb->s_time_gran = 1;
773 
774 	inode = rpc_get_inode(sb, S_IFDIR | 0755);
775 	if (!inode)
776 		return -ENOMEM;
777 	root = d_alloc_root(inode);
778 	if (!root) {
779 		iput(inode);
780 		return -ENOMEM;
781 	}
782 	if (rpc_populate(root, files, RPCAUTH_Root + 1, RPCAUTH_RootEOF))
783 		goto out;
784 	sb->s_root = root;
785 	return 0;
786 out:
787 	d_genocide(root);
788 	dput(root);
789 	return -ENOMEM;
790 }
791 
792 static struct super_block *
793 rpc_get_sb(struct file_system_type *fs_type,
794 		int flags, const char *dev_name, void *data)
795 {
796 	return get_sb_single(fs_type, flags, data, rpc_fill_super);
797 }
798 
799 static struct file_system_type rpc_pipe_fs_type = {
800 	.owner		= THIS_MODULE,
801 	.name		= "rpc_pipefs",
802 	.get_sb		= rpc_get_sb,
803 	.kill_sb	= kill_litter_super,
804 };
805 
806 static void
807 init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
808 {
809 	struct rpc_inode *rpci = (struct rpc_inode *) foo;
810 
811 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
812 	    SLAB_CTOR_CONSTRUCTOR) {
813 		inode_init_once(&rpci->vfs_inode);
814 		rpci->private = NULL;
815 		rpci->nreaders = 0;
816 		rpci->nwriters = 0;
817 		INIT_LIST_HEAD(&rpci->in_upcall);
818 		INIT_LIST_HEAD(&rpci->pipe);
819 		rpci->pipelen = 0;
820 		init_waitqueue_head(&rpci->waitq);
821 		INIT_WORK(&rpci->queue_timeout, rpc_timeout_upcall_queue, rpci);
822 		rpci->ops = NULL;
823 	}
824 }
825 
826 int register_rpc_pipefs(void)
827 {
828 	rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",
829                                              sizeof(struct rpc_inode),
830                                              0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
831                                              init_once, NULL);
832 	if (!rpc_inode_cachep)
833 		return -ENOMEM;
834 	register_filesystem(&rpc_pipe_fs_type);
835 	return 0;
836 }
837 
838 void unregister_rpc_pipefs(void)
839 {
840 	if (kmem_cache_destroy(rpc_inode_cachep))
841 		printk(KERN_WARNING "RPC: unable to free inode cache\n");
842 	unregister_filesystem(&rpc_pipe_fs_type);
843 }
844