xref: /openbmc/linux/fs/afs/super.c (revision 2c684d89) 
1 /* AFS superblock handling
2  *
3  * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
4  *
5  * This software may be freely redistributed under the terms of the
6  * GNU General Public License.
7  *
8  * You should have received a copy of the GNU General Public License
9  * along with this program; if not, write to the Free Software
10  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
11  *
12  * Authors: David Howells <dhowells@redhat.com>
13  *          David Woodhouse <dwmw2@infradead.org>
14  *
15  */
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/mount.h>
20 #include <linux/init.h>
21 #include <linux/slab.h>
22 #include <linux/fs.h>
23 #include <linux/pagemap.h>
24 #include <linux/parser.h>
25 #include <linux/statfs.h>
26 #include <linux/sched.h>
27 #include <linux/nsproxy.h>
28 #include <net/net_namespace.h>
29 #include "internal.h"
30 
31 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
32 
33 static void afs_i_init_once(void *foo);
34 static struct dentry *afs_mount(struct file_system_type *fs_type,
35 		      int flags, const char *dev_name, void *data);
36 static void afs_kill_super(struct super_block *sb);
37 static struct inode *afs_alloc_inode(struct super_block *sb);
38 static void afs_destroy_inode(struct inode *inode);
39 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
40 
41 struct file_system_type afs_fs_type = {
42 	.owner		= THIS_MODULE,
43 	.name		= "afs",
44 	.mount		= afs_mount,
45 	.kill_sb	= afs_kill_super,
46 	.fs_flags	= 0,
47 };
48 MODULE_ALIAS_FS("afs");
49 
50 static const struct super_operations afs_super_ops = {
51 	.statfs		= afs_statfs,
52 	.alloc_inode	= afs_alloc_inode,
53 	.drop_inode	= afs_drop_inode,
54 	.destroy_inode	= afs_destroy_inode,
55 	.evict_inode	= afs_evict_inode,
56 	.show_options	= generic_show_options,
57 };
58 
59 static struct kmem_cache *afs_inode_cachep;
60 static atomic_t afs_count_active_inodes;
61 
62 enum {
63 	afs_no_opt,
64 	afs_opt_cell,
65 	afs_opt_rwpath,
66 	afs_opt_vol,
67 	afs_opt_autocell,
68 };
69 
70 static const match_table_t afs_options_list = {
71 	{ afs_opt_cell,		"cell=%s"	},
72 	{ afs_opt_rwpath,	"rwpath"	},
73 	{ afs_opt_vol,		"vol=%s"	},
74 	{ afs_opt_autocell,	"autocell"	},
75 	{ afs_no_opt,		NULL		},
76 };
77 
78 /*
79  * initialise the filesystem
80  */
81 int __init afs_fs_init(void)
82 {
83 	int ret;
84 
85 	_enter("");
86 
87 	/* create ourselves an inode cache */
88 	atomic_set(&afs_count_active_inodes, 0);
89 
90 	ret = -ENOMEM;
91 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
92 					     sizeof(struct afs_vnode),
93 					     0,
94 					     SLAB_HWCACHE_ALIGN,
95 					     afs_i_init_once);
96 	if (!afs_inode_cachep) {
97 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
98 		return ret;
99 	}
100 
101 	/* now export our filesystem to lesser mortals */
102 	ret = register_filesystem(&afs_fs_type);
103 	if (ret < 0) {
104 		kmem_cache_destroy(afs_inode_cachep);
105 		_leave(" = %d", ret);
106 		return ret;
107 	}
108 
109 	_leave(" = 0");
110 	return 0;
111 }
112 
113 /*
114  * clean up the filesystem
115  */
116 void __exit afs_fs_exit(void)
117 {
118 	_enter("");
119 
120 	afs_mntpt_kill_timer();
121 	unregister_filesystem(&afs_fs_type);
122 
123 	if (atomic_read(&afs_count_active_inodes) != 0) {
124 		printk("kAFS: %d active inode objects still present\n",
125 		       atomic_read(&afs_count_active_inodes));
126 		BUG();
127 	}
128 
129 	/*
130 	 * Make sure all delayed rcu free inodes are flushed before we
131 	 * destroy cache.
132 	 */
133 	rcu_barrier();
134 	kmem_cache_destroy(afs_inode_cachep);
135 	_leave("");
136 }
137 
138 /*
139  * parse the mount options
140  * - this function has been shamelessly adapted from the ext3 fs which
141  *   shamelessly adapted it from the msdos fs
142  */
143 static int afs_parse_options(struct afs_mount_params *params,
144 			     char *options, const char **devname)
145 {
146 	struct afs_cell *cell;
147 	substring_t args[MAX_OPT_ARGS];
148 	char *p;
149 	int token;
150 
151 	_enter("%s", options);
152 
153 	options[PAGE_SIZE - 1] = 0;
154 
155 	while ((p = strsep(&options, ","))) {
156 		if (!*p)
157 			continue;
158 
159 		token = match_token(p, afs_options_list, args);
160 		switch (token) {
161 		case afs_opt_cell:
162 			cell = afs_cell_lookup(args[0].from,
163 					       args[0].to - args[0].from,
164 					       false);
165 			if (IS_ERR(cell))
166 				return PTR_ERR(cell);
167 			afs_put_cell(params->cell);
168 			params->cell = cell;
169 			break;
170 
171 		case afs_opt_rwpath:
172 			params->rwpath = 1;
173 			break;
174 
175 		case afs_opt_vol:
176 			*devname = args[0].from;
177 			break;
178 
179 		case afs_opt_autocell:
180 			params->autocell = 1;
181 			break;
182 
183 		default:
184 			printk(KERN_ERR "kAFS:"
185 			       " Unknown or invalid mount option: '%s'\n", p);
186 			return -EINVAL;
187 		}
188 	}
189 
190 	_leave(" = 0");
191 	return 0;
192 }
193 
194 /*
195  * parse a device name to get cell name, volume name, volume type and R/W
196  * selector
197  * - this can be one of the following:
198  *	"%[cell:]volume[.]"		R/W volume
199  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
200  *					 or R/W (rwpath=1) volume
201  *	"%[cell:]volume.readonly"	R/O volume
202  *	"#[cell:]volume.readonly"	R/O volume
203  *	"%[cell:]volume.backup"		Backup volume
204  *	"#[cell:]volume.backup"		Backup volume
205  */
206 static int afs_parse_device_name(struct afs_mount_params *params,
207 				 const char *name)
208 {
209 	struct afs_cell *cell;
210 	const char *cellname, *suffix;
211 	int cellnamesz;
212 
213 	_enter(",%s", name);
214 
215 	if (!name) {
216 		printk(KERN_ERR "kAFS: no volume name specified\n");
217 		return -EINVAL;
218 	}
219 
220 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
221 		printk(KERN_ERR "kAFS: unparsable volume name\n");
222 		return -EINVAL;
223 	}
224 
225 	/* determine the type of volume we're looking for */
226 	params->type = AFSVL_ROVOL;
227 	params->force = false;
228 	if (params->rwpath || name[0] == '%') {
229 		params->type = AFSVL_RWVOL;
230 		params->force = true;
231 	}
232 	name++;
233 
234 	/* split the cell name out if there is one */
235 	params->volname = strchr(name, ':');
236 	if (params->volname) {
237 		cellname = name;
238 		cellnamesz = params->volname - name;
239 		params->volname++;
240 	} else {
241 		params->volname = name;
242 		cellname = NULL;
243 		cellnamesz = 0;
244 	}
245 
246 	/* the volume type is further affected by a possible suffix */
247 	suffix = strrchr(params->volname, '.');
248 	if (suffix) {
249 		if (strcmp(suffix, ".readonly") == 0) {
250 			params->type = AFSVL_ROVOL;
251 			params->force = true;
252 		} else if (strcmp(suffix, ".backup") == 0) {
253 			params->type = AFSVL_BACKVOL;
254 			params->force = true;
255 		} else if (suffix[1] == 0) {
256 		} else {
257 			suffix = NULL;
258 		}
259 	}
260 
261 	params->volnamesz = suffix ?
262 		suffix - params->volname : strlen(params->volname);
263 
264 	_debug("cell %*.*s [%p]",
265 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
266 
267 	/* lookup the cell record */
268 	if (cellname || !params->cell) {
269 		cell = afs_cell_lookup(cellname, cellnamesz, true);
270 		if (IS_ERR(cell)) {
271 			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
272 			       cellnamesz, cellnamesz, cellname ?: "");
273 			return PTR_ERR(cell);
274 		}
275 		afs_put_cell(params->cell);
276 		params->cell = cell;
277 	}
278 
279 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
280 	       params->cell->name, params->cell,
281 	       params->volnamesz, params->volnamesz, params->volname,
282 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
283 
284 	return 0;
285 }
286 
287 /*
288  * check a superblock to see if it's the one we're looking for
289  */
290 static int afs_test_super(struct super_block *sb, void *data)
291 {
292 	struct afs_super_info *as1 = data;
293 	struct afs_super_info *as = sb->s_fs_info;
294 
295 	return as->volume == as1->volume;
296 }
297 
298 static int afs_set_super(struct super_block *sb, void *data)
299 {
300 	sb->s_fs_info = data;
301 	return set_anon_super(sb, NULL);
302 }
303 
304 /*
305  * fill in the superblock
306  */
307 static int afs_fill_super(struct super_block *sb,
308 			  struct afs_mount_params *params)
309 {
310 	struct afs_super_info *as = sb->s_fs_info;
311 	struct afs_fid fid;
312 	struct inode *inode = NULL;
313 	int ret;
314 
315 	_enter("");
316 
317 	/* fill in the superblock */
318 	sb->s_blocksize		= PAGE_CACHE_SIZE;
319 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
320 	sb->s_magic		= AFS_FS_MAGIC;
321 	sb->s_op		= &afs_super_ops;
322 	sb->s_bdi		= &as->volume->bdi;
323 	strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
324 
325 	/* allocate the root inode and dentry */
326 	fid.vid		= as->volume->vid;
327 	fid.vnode	= 1;
328 	fid.unique	= 1;
329 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
330 	if (IS_ERR(inode))
331 		return PTR_ERR(inode);
332 
333 	if (params->autocell)
334 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
335 
336 	ret = -ENOMEM;
337 	sb->s_root = d_make_root(inode);
338 	if (!sb->s_root)
339 		goto error;
340 
341 	sb->s_d_op = &afs_fs_dentry_operations;
342 
343 	_leave(" = 0");
344 	return 0;
345 
346 error:
347 	_leave(" = %d", ret);
348 	return ret;
349 }
350 
351 /*
352  * get an AFS superblock
353  */
354 static struct dentry *afs_mount(struct file_system_type *fs_type,
355 		      int flags, const char *dev_name, void *options)
356 {
357 	struct afs_mount_params params;
358 	struct super_block *sb;
359 	struct afs_volume *vol;
360 	struct key *key;
361 	char *new_opts = kstrdup(options, GFP_KERNEL);
362 	struct afs_super_info *as;
363 	int ret;
364 
365 	_enter(",,%s,%p", dev_name, options);
366 
367 	memset(&params, 0, sizeof(params));
368 
369 	ret = -EINVAL;
370 	if (current->nsproxy->net_ns != &init_net)
371 		goto error;
372 
373 	/* parse the options and device name */
374 	if (options) {
375 		ret = afs_parse_options(&params, options, &dev_name);
376 		if (ret < 0)
377 			goto error;
378 	}
379 
380 	ret = afs_parse_device_name(&params, dev_name);
381 	if (ret < 0)
382 		goto error;
383 
384 	/* try and do the mount securely */
385 	key = afs_request_key(params.cell);
386 	if (IS_ERR(key)) {
387 		_leave(" = %ld [key]", PTR_ERR(key));
388 		ret = PTR_ERR(key);
389 		goto error;
390 	}
391 	params.key = key;
392 
393 	/* parse the device name */
394 	vol = afs_volume_lookup(&params);
395 	if (IS_ERR(vol)) {
396 		ret = PTR_ERR(vol);
397 		goto error;
398 	}
399 
400 	/* allocate a superblock info record */
401 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
402 	if (!as) {
403 		ret = -ENOMEM;
404 		afs_put_volume(vol);
405 		goto error;
406 	}
407 	as->volume = vol;
408 
409 	/* allocate a deviceless superblock */
410 	sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
411 	if (IS_ERR(sb)) {
412 		ret = PTR_ERR(sb);
413 		afs_put_volume(vol);
414 		kfree(as);
415 		goto error;
416 	}
417 
418 	if (!sb->s_root) {
419 		/* initial superblock/root creation */
420 		_debug("create");
421 		ret = afs_fill_super(sb, &params);
422 		if (ret < 0) {
423 			deactivate_locked_super(sb);
424 			goto error;
425 		}
426 		save_mount_options(sb, new_opts);
427 		sb->s_flags |= MS_ACTIVE;
428 	} else {
429 		_debug("reuse");
430 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
431 		afs_put_volume(vol);
432 		kfree(as);
433 	}
434 
435 	afs_put_cell(params.cell);
436 	kfree(new_opts);
437 	_leave(" = 0 [%p]", sb);
438 	return dget(sb->s_root);
439 
440 error:
441 	afs_put_cell(params.cell);
442 	key_put(params.key);
443 	kfree(new_opts);
444 	_leave(" = %d", ret);
445 	return ERR_PTR(ret);
446 }
447 
448 static void afs_kill_super(struct super_block *sb)
449 {
450 	struct afs_super_info *as = sb->s_fs_info;
451 	kill_anon_super(sb);
452 	afs_put_volume(as->volume);
453 	kfree(as);
454 }
455 
456 /*
457  * initialise an inode cache slab element prior to any use
458  */
459 static void afs_i_init_once(void *_vnode)
460 {
461 	struct afs_vnode *vnode = _vnode;
462 
463 	memset(vnode, 0, sizeof(*vnode));
464 	inode_init_once(&vnode->vfs_inode);
465 	init_waitqueue_head(&vnode->update_waitq);
466 	mutex_init(&vnode->permits_lock);
467 	mutex_init(&vnode->validate_lock);
468 	spin_lock_init(&vnode->writeback_lock);
469 	spin_lock_init(&vnode->lock);
470 	INIT_LIST_HEAD(&vnode->writebacks);
471 	INIT_LIST_HEAD(&vnode->pending_locks);
472 	INIT_LIST_HEAD(&vnode->granted_locks);
473 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
474 	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
475 }
476 
477 /*
478  * allocate an AFS inode struct from our slab cache
479  */
480 static struct inode *afs_alloc_inode(struct super_block *sb)
481 {
482 	struct afs_vnode *vnode;
483 
484 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
485 	if (!vnode)
486 		return NULL;
487 
488 	atomic_inc(&afs_count_active_inodes);
489 
490 	memset(&vnode->fid, 0, sizeof(vnode->fid));
491 	memset(&vnode->status, 0, sizeof(vnode->status));
492 
493 	vnode->volume		= NULL;
494 	vnode->update_cnt	= 0;
495 	vnode->flags		= 1 << AFS_VNODE_UNSET;
496 	vnode->cb_promised	= false;
497 
498 	_leave(" = %p", &vnode->vfs_inode);
499 	return &vnode->vfs_inode;
500 }
501 
502 static void afs_i_callback(struct rcu_head *head)
503 {
504 	struct inode *inode = container_of(head, struct inode, i_rcu);
505 	struct afs_vnode *vnode = AFS_FS_I(inode);
506 	kmem_cache_free(afs_inode_cachep, vnode);
507 }
508 
509 /*
510  * destroy an AFS inode struct
511  */
512 static void afs_destroy_inode(struct inode *inode)
513 {
514 	struct afs_vnode *vnode = AFS_FS_I(inode);
515 
516 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
517 
518 	_debug("DESTROY INODE %p", inode);
519 
520 	ASSERTCMP(vnode->server, ==, NULL);
521 
522 	call_rcu(&inode->i_rcu, afs_i_callback);
523 	atomic_dec(&afs_count_active_inodes);
524 }
525 
526 /*
527  * return information about an AFS volume
528  */
529 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
530 {
531 	struct afs_volume_status vs;
532 	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
533 	struct key *key;
534 	int ret;
535 
536 	key = afs_request_key(vnode->volume->cell);
537 	if (IS_ERR(key))
538 		return PTR_ERR(key);
539 
540 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
541 	key_put(key);
542 	if (ret < 0) {
543 		_leave(" = %d", ret);
544 		return ret;
545 	}
546 
547 	buf->f_type	= dentry->d_sb->s_magic;
548 	buf->f_bsize	= AFS_BLOCK_SIZE;
549 	buf->f_namelen	= AFSNAMEMAX - 1;
550 
551 	if (vs.max_quota == 0)
552 		buf->f_blocks = vs.part_max_blocks;
553 	else
554 		buf->f_blocks = vs.max_quota;
555 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
556 	return 0;
557 }
558