xref: /openbmc/linux/fs/fuse/inode.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
4 
5   This program can be distributed under the terms of the GNU GPL.
6   See the file COPYING.
7 */
8 
9 #include "fuse_i.h"
10 
11 #include <linux/pagemap.h>
12 #include <linux/slab.h>
13 #include <linux/file.h>
14 #include <linux/mount.h>
15 #include <linux/seq_file.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/parser.h>
19 #include <linux/statfs.h>
20 
21 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
22 MODULE_DESCRIPTION("Filesystem in Userspace");
23 MODULE_LICENSE("GPL");
24 
25 spinlock_t fuse_lock;
26 static kmem_cache_t *fuse_inode_cachep;
27 
28 #define FUSE_SUPER_MAGIC 0x65735546
29 
30 struct fuse_mount_data {
31 	int fd;
32 	unsigned rootmode;
33 	unsigned user_id;
34 	unsigned group_id;
35 	unsigned fd_present : 1;
36 	unsigned rootmode_present : 1;
37 	unsigned user_id_present : 1;
38 	unsigned group_id_present : 1;
39 	unsigned flags;
40 	unsigned max_read;
41 };
42 
43 static struct inode *fuse_alloc_inode(struct super_block *sb)
44 {
45 	struct inode *inode;
46 	struct fuse_inode *fi;
47 
48 	inode = kmem_cache_alloc(fuse_inode_cachep, SLAB_KERNEL);
49 	if (!inode)
50 		return NULL;
51 
52 	fi = get_fuse_inode(inode);
53 	fi->i_time = jiffies - 1;
54 	fi->nodeid = 0;
55 	fi->nlookup = 0;
56 	fi->forget_req = fuse_request_alloc();
57 	if (!fi->forget_req) {
58 		kmem_cache_free(fuse_inode_cachep, inode);
59 		return NULL;
60 	}
61 
62 	return inode;
63 }
64 
65 static void fuse_destroy_inode(struct inode *inode)
66 {
67 	struct fuse_inode *fi = get_fuse_inode(inode);
68 	if (fi->forget_req)
69 		fuse_request_free(fi->forget_req);
70 	kmem_cache_free(fuse_inode_cachep, inode);
71 }
72 
73 static void fuse_read_inode(struct inode *inode)
74 {
75 	/* No op */
76 }
77 
78 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
79 		      unsigned long nodeid, u64 nlookup)
80 {
81 	struct fuse_forget_in *inarg = &req->misc.forget_in;
82 	inarg->nlookup = nlookup;
83 	req->in.h.opcode = FUSE_FORGET;
84 	req->in.h.nodeid = nodeid;
85 	req->in.numargs = 1;
86 	req->in.args[0].size = sizeof(struct fuse_forget_in);
87 	req->in.args[0].value = inarg;
88 	request_send_noreply(fc, req);
89 }
90 
91 static void fuse_clear_inode(struct inode *inode)
92 {
93 	if (inode->i_sb->s_flags & MS_ACTIVE) {
94 		struct fuse_conn *fc = get_fuse_conn(inode);
95 		struct fuse_inode *fi = get_fuse_inode(inode);
96 		fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
97 		fi->forget_req = NULL;
98 	}
99 }
100 
101 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
102 {
103 	if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
104 		invalidate_inode_pages(inode->i_mapping);
105 
106 	inode->i_ino     = attr->ino;
107 	inode->i_mode    = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
108 	inode->i_nlink   = attr->nlink;
109 	inode->i_uid     = attr->uid;
110 	inode->i_gid     = attr->gid;
111 	i_size_write(inode, attr->size);
112 	inode->i_blksize = PAGE_CACHE_SIZE;
113 	inode->i_blocks  = attr->blocks;
114 	inode->i_atime.tv_sec   = attr->atime;
115 	inode->i_atime.tv_nsec  = attr->atimensec;
116 	inode->i_mtime.tv_sec   = attr->mtime;
117 	inode->i_mtime.tv_nsec  = attr->mtimensec;
118 	inode->i_ctime.tv_sec   = attr->ctime;
119 	inode->i_ctime.tv_nsec  = attr->ctimensec;
120 }
121 
122 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
123 {
124 	inode->i_mode = attr->mode & S_IFMT;
125 	i_size_write(inode, attr->size);
126 	if (S_ISREG(inode->i_mode)) {
127 		fuse_init_common(inode);
128 		fuse_init_file_inode(inode);
129 	} else if (S_ISDIR(inode->i_mode))
130 		fuse_init_dir(inode);
131 	else if (S_ISLNK(inode->i_mode))
132 		fuse_init_symlink(inode);
133 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
134 		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
135 		fuse_init_common(inode);
136 		init_special_inode(inode, inode->i_mode,
137 				   new_decode_dev(attr->rdev));
138 	} else {
139 		/* Don't let user create weird files */
140 		inode->i_mode = S_IFREG;
141 		fuse_init_common(inode);
142 		fuse_init_file_inode(inode);
143 	}
144 }
145 
146 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
147 {
148 	unsigned long nodeid = *(unsigned long *) _nodeidp;
149 	if (get_node_id(inode) == nodeid)
150 		return 1;
151 	else
152 		return 0;
153 }
154 
155 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
156 {
157 	unsigned long nodeid = *(unsigned long *) _nodeidp;
158 	get_fuse_inode(inode)->nodeid = nodeid;
159 	return 0;
160 }
161 
162 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
163 			int generation, struct fuse_attr *attr)
164 {
165 	struct inode *inode;
166 	struct fuse_inode *fi;
167 	struct fuse_conn *fc = get_fuse_conn_super(sb);
168 	int retried = 0;
169 
170  retry:
171 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
172 	if (!inode)
173 		return NULL;
174 
175 	if ((inode->i_state & I_NEW)) {
176 		inode->i_flags |= S_NOATIME|S_NOCMTIME;
177 		inode->i_generation = generation;
178 		inode->i_data.backing_dev_info = &fc->bdi;
179 		fuse_init_inode(inode, attr);
180 		unlock_new_inode(inode);
181 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
182 		BUG_ON(retried);
183 		/* Inode has changed type, any I/O on the old should fail */
184 		make_bad_inode(inode);
185 		iput(inode);
186 		retried = 1;
187 		goto retry;
188 	}
189 
190 	fi = get_fuse_inode(inode);
191 	fi->nlookup ++;
192 	fuse_change_attributes(inode, attr);
193 	return inode;
194 }
195 
196 static void fuse_put_super(struct super_block *sb)
197 {
198 	struct fuse_conn *fc = get_fuse_conn_super(sb);
199 
200 	down_write(&fc->sbput_sem);
201 	while (!list_empty(&fc->background))
202 		fuse_release_background(list_entry(fc->background.next,
203 						   struct fuse_req, bg_entry));
204 
205 	spin_lock(&fuse_lock);
206 	fc->mounted = 0;
207 	fc->user_id = 0;
208 	fc->group_id = 0;
209 	fc->flags = 0;
210 	/* Flush all readers on this fs */
211 	wake_up_all(&fc->waitq);
212 	up_write(&fc->sbput_sem);
213 	fuse_release_conn(fc);
214 	spin_unlock(&fuse_lock);
215 }
216 
217 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
218 {
219 	stbuf->f_type    = FUSE_SUPER_MAGIC;
220 	stbuf->f_bsize   = attr->bsize;
221 	stbuf->f_blocks  = attr->blocks;
222 	stbuf->f_bfree   = attr->bfree;
223 	stbuf->f_bavail  = attr->bavail;
224 	stbuf->f_files   = attr->files;
225 	stbuf->f_ffree   = attr->ffree;
226 	stbuf->f_namelen = attr->namelen;
227 	/* fsid is left zero */
228 }
229 
230 static int fuse_statfs(struct super_block *sb, struct kstatfs *buf)
231 {
232 	struct fuse_conn *fc = get_fuse_conn_super(sb);
233 	struct fuse_req *req;
234 	struct fuse_statfs_out outarg;
235 	int err;
236 
237         req = fuse_get_request(fc);
238 	if (!req)
239 		return -EINTR;
240 
241 	req->in.numargs = 0;
242 	req->in.h.opcode = FUSE_STATFS;
243 	req->out.numargs = 1;
244 	req->out.args[0].size = sizeof(outarg);
245 	req->out.args[0].value = &outarg;
246 	request_send(fc, req);
247 	err = req->out.h.error;
248 	if (!err)
249 		convert_fuse_statfs(buf, &outarg.st);
250 	fuse_put_request(fc, req);
251 	return err;
252 }
253 
254 enum {
255 	OPT_FD,
256 	OPT_ROOTMODE,
257 	OPT_USER_ID,
258 	OPT_GROUP_ID,
259 	OPT_DEFAULT_PERMISSIONS,
260 	OPT_ALLOW_OTHER,
261 	OPT_MAX_READ,
262 	OPT_ERR
263 };
264 
265 static match_table_t tokens = {
266 	{OPT_FD,			"fd=%u"},
267 	{OPT_ROOTMODE,			"rootmode=%o"},
268 	{OPT_USER_ID,			"user_id=%u"},
269 	{OPT_GROUP_ID,			"group_id=%u"},
270 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
271 	{OPT_ALLOW_OTHER,		"allow_other"},
272 	{OPT_MAX_READ,			"max_read=%u"},
273 	{OPT_ERR,			NULL}
274 };
275 
276 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
277 {
278 	char *p;
279 	memset(d, 0, sizeof(struct fuse_mount_data));
280 	d->max_read = ~0;
281 
282 	while ((p = strsep(&opt, ",")) != NULL) {
283 		int token;
284 		int value;
285 		substring_t args[MAX_OPT_ARGS];
286 		if (!*p)
287 			continue;
288 
289 		token = match_token(p, tokens, args);
290 		switch (token) {
291 		case OPT_FD:
292 			if (match_int(&args[0], &value))
293 				return 0;
294 			d->fd = value;
295 			d->fd_present = 1;
296 			break;
297 
298 		case OPT_ROOTMODE:
299 			if (match_octal(&args[0], &value))
300 				return 0;
301 			d->rootmode = value;
302 			d->rootmode_present = 1;
303 			break;
304 
305 		case OPT_USER_ID:
306 			if (match_int(&args[0], &value))
307 				return 0;
308 			d->user_id = value;
309 			d->user_id_present = 1;
310 			break;
311 
312 		case OPT_GROUP_ID:
313 			if (match_int(&args[0], &value))
314 				return 0;
315 			d->group_id = value;
316 			d->group_id_present = 1;
317 			break;
318 
319 		case OPT_DEFAULT_PERMISSIONS:
320 			d->flags |= FUSE_DEFAULT_PERMISSIONS;
321 			break;
322 
323 		case OPT_ALLOW_OTHER:
324 			d->flags |= FUSE_ALLOW_OTHER;
325 			break;
326 
327 		case OPT_MAX_READ:
328 			if (match_int(&args[0], &value))
329 				return 0;
330 			d->max_read = value;
331 			break;
332 
333 		default:
334 			return 0;
335 		}
336 	}
337 
338 	if (!d->fd_present || !d->rootmode_present ||
339 	    !d->user_id_present || !d->group_id_present)
340 		return 0;
341 
342 	return 1;
343 }
344 
345 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
346 {
347 	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
348 
349 	seq_printf(m, ",user_id=%u", fc->user_id);
350 	seq_printf(m, ",group_id=%u", fc->group_id);
351 	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
352 		seq_puts(m, ",default_permissions");
353 	if (fc->flags & FUSE_ALLOW_OTHER)
354 		seq_puts(m, ",allow_other");
355 	if (fc->max_read != ~0)
356 		seq_printf(m, ",max_read=%u", fc->max_read);
357 	return 0;
358 }
359 
360 static void free_conn(struct fuse_conn *fc)
361 {
362 	while (!list_empty(&fc->unused_list)) {
363 		struct fuse_req *req;
364 		req = list_entry(fc->unused_list.next, struct fuse_req, list);
365 		list_del(&req->list);
366 		fuse_request_free(req);
367 	}
368 	kfree(fc);
369 }
370 
371 /* Must be called with the fuse lock held */
372 void fuse_release_conn(struct fuse_conn *fc)
373 {
374 	fc->count--;
375 	if (!fc->count)
376 		free_conn(fc);
377 }
378 
379 static struct fuse_conn *new_conn(void)
380 {
381 	struct fuse_conn *fc;
382 
383 	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
384 	if (fc != NULL) {
385 		int i;
386 		memset(fc, 0, sizeof(*fc));
387 		init_waitqueue_head(&fc->waitq);
388 		INIT_LIST_HEAD(&fc->pending);
389 		INIT_LIST_HEAD(&fc->processing);
390 		INIT_LIST_HEAD(&fc->unused_list);
391 		INIT_LIST_HEAD(&fc->background);
392 		sema_init(&fc->outstanding_sem, 0);
393 		init_rwsem(&fc->sbput_sem);
394 		for (i = 0; i < FUSE_MAX_OUTSTANDING; i++) {
395 			struct fuse_req *req = fuse_request_alloc();
396 			if (!req) {
397 				free_conn(fc);
398 				return NULL;
399 			}
400 			list_add(&req->list, &fc->unused_list);
401 		}
402 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
403 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
404 		fc->reqctr = 0;
405 	}
406 	return fc;
407 }
408 
409 static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
410 {
411 	struct fuse_conn *fc;
412 
413 	if (file->f_op != &fuse_dev_operations)
414 		return ERR_PTR(-EINVAL);
415 	fc = new_conn();
416 	if (fc == NULL)
417 		return ERR_PTR(-ENOMEM);
418 	spin_lock(&fuse_lock);
419 	if (file->private_data) {
420 		free_conn(fc);
421 		fc = ERR_PTR(-EINVAL);
422 	} else {
423 		file->private_data = fc;
424 		*get_fuse_conn_super_p(sb) = fc;
425 		fc->mounted = 1;
426 		fc->connected = 1;
427 		fc->count = 2;
428 	}
429 	spin_unlock(&fuse_lock);
430 	return fc;
431 }
432 
433 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
434 {
435 	struct fuse_attr attr;
436 	memset(&attr, 0, sizeof(attr));
437 
438 	attr.mode = mode;
439 	attr.ino = FUSE_ROOT_ID;
440 	return fuse_iget(sb, 1, 0, &attr);
441 }
442 
443 static struct super_operations fuse_super_operations = {
444 	.alloc_inode    = fuse_alloc_inode,
445 	.destroy_inode  = fuse_destroy_inode,
446 	.read_inode	= fuse_read_inode,
447 	.clear_inode	= fuse_clear_inode,
448 	.put_super	= fuse_put_super,
449 	.statfs		= fuse_statfs,
450 	.show_options	= fuse_show_options,
451 };
452 
453 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
454 {
455 	struct fuse_conn *fc;
456 	struct inode *root;
457 	struct fuse_mount_data d;
458 	struct file *file;
459 	int err;
460 
461 	if (!parse_fuse_opt((char *) data, &d))
462 		return -EINVAL;
463 
464 	sb->s_blocksize = PAGE_CACHE_SIZE;
465 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
466 	sb->s_magic = FUSE_SUPER_MAGIC;
467 	sb->s_op = &fuse_super_operations;
468 	sb->s_maxbytes = MAX_LFS_FILESIZE;
469 
470 	file = fget(d.fd);
471 	if (!file)
472 		return -EINVAL;
473 
474 	fc = get_conn(file, sb);
475 	fput(file);
476 	if (IS_ERR(fc))
477 		return PTR_ERR(fc);
478 
479 	fc->flags = d.flags;
480 	fc->user_id = d.user_id;
481 	fc->group_id = d.group_id;
482 	fc->max_read = d.max_read;
483 	if (fc->max_read / PAGE_CACHE_SIZE < fc->bdi.ra_pages)
484 		fc->bdi.ra_pages = fc->max_read / PAGE_CACHE_SIZE;
485 	fc->max_write = FUSE_MAX_IN / 2;
486 
487 	err = -ENOMEM;
488 	root = get_root_inode(sb, d.rootmode);
489 	if (root == NULL)
490 		goto err;
491 
492 	sb->s_root = d_alloc_root(root);
493 	if (!sb->s_root) {
494 		iput(root);
495 		goto err;
496 	}
497 	fuse_send_init(fc);
498 	return 0;
499 
500  err:
501 	spin_lock(&fuse_lock);
502 	fuse_release_conn(fc);
503 	spin_unlock(&fuse_lock);
504 	return err;
505 }
506 
507 static struct super_block *fuse_get_sb(struct file_system_type *fs_type,
508 				       int flags, const char *dev_name,
509 				       void *raw_data)
510 {
511 	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super);
512 }
513 
514 static struct file_system_type fuse_fs_type = {
515 	.owner		= THIS_MODULE,
516 	.name		= "fuse",
517 	.get_sb		= fuse_get_sb,
518 	.kill_sb	= kill_anon_super,
519 };
520 
521 static void fuse_inode_init_once(void *foo, kmem_cache_t *cachep,
522 				 unsigned long flags)
523 {
524 	struct inode * inode = foo;
525 
526 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
527 	    SLAB_CTOR_CONSTRUCTOR)
528 		inode_init_once(inode);
529 }
530 
531 static int __init fuse_fs_init(void)
532 {
533 	int err;
534 
535 	err = register_filesystem(&fuse_fs_type);
536 	if (err)
537 		printk("fuse: failed to register filesystem\n");
538 	else {
539 		fuse_inode_cachep = kmem_cache_create("fuse_inode",
540 						      sizeof(struct fuse_inode),
541 						      0, SLAB_HWCACHE_ALIGN,
542 						      fuse_inode_init_once, NULL);
543 		if (!fuse_inode_cachep) {
544 			unregister_filesystem(&fuse_fs_type);
545 			err = -ENOMEM;
546 		}
547 	}
548 
549 	return err;
550 }
551 
552 static void fuse_fs_cleanup(void)
553 {
554 	unregister_filesystem(&fuse_fs_type);
555 	kmem_cache_destroy(fuse_inode_cachep);
556 }
557 
558 static int __init fuse_init(void)
559 {
560 	int res;
561 
562 	printk("fuse init (API version %i.%i)\n",
563 	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
564 
565 	spin_lock_init(&fuse_lock);
566 	res = fuse_fs_init();
567 	if (res)
568 		goto err;
569 
570 	res = fuse_dev_init();
571 	if (res)
572 		goto err_fs_cleanup;
573 
574 	return 0;
575 
576  err_fs_cleanup:
577 	fuse_fs_cleanup();
578  err:
579 	return res;
580 }
581 
582 static void __exit fuse_exit(void)
583 {
584 	printk(KERN_DEBUG "fuse exit\n");
585 
586 	fuse_fs_cleanup();
587 	fuse_dev_cleanup();
588 }
589 
590 module_init(fuse_init);
591 module_exit(fuse_exit);
592