xref: /openbmc/linux/fs/afs/super.c (revision 981ab3f1) 
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 static int afs_show_devname(struct seq_file *m, struct dentry *root);
41 static int afs_show_options(struct seq_file *m, struct dentry *root);
42 
43 struct file_system_type afs_fs_type = {
44 	.owner		= THIS_MODULE,
45 	.name		= "afs",
46 	.mount		= afs_mount,
47 	.kill_sb	= afs_kill_super,
48 	.fs_flags	= 0,
49 };
50 MODULE_ALIAS_FS("afs");
51 
52 static const struct super_operations afs_super_ops = {
53 	.statfs		= afs_statfs,
54 	.alloc_inode	= afs_alloc_inode,
55 	.drop_inode	= afs_drop_inode,
56 	.destroy_inode	= afs_destroy_inode,
57 	.evict_inode	= afs_evict_inode,
58 	.show_devname	= afs_show_devname,
59 	.show_options	= afs_show_options,
60 };
61 
62 static struct kmem_cache *afs_inode_cachep;
63 static atomic_t afs_count_active_inodes;
64 
65 enum {
66 	afs_no_opt,
67 	afs_opt_cell,
68 	afs_opt_rwpath,
69 	afs_opt_vol,
70 	afs_opt_autocell,
71 };
72 
73 static const match_table_t afs_options_list = {
74 	{ afs_opt_cell,		"cell=%s"	},
75 	{ afs_opt_rwpath,	"rwpath"	},
76 	{ afs_opt_vol,		"vol=%s"	},
77 	{ afs_opt_autocell,	"autocell"	},
78 	{ afs_no_opt,		NULL		},
79 };
80 
81 /*
82  * initialise the filesystem
83  */
84 int __init afs_fs_init(void)
85 {
86 	int ret;
87 
88 	_enter("");
89 
90 	/* create ourselves an inode cache */
91 	atomic_set(&afs_count_active_inodes, 0);
92 
93 	ret = -ENOMEM;
94 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
95 					     sizeof(struct afs_vnode),
96 					     0,
97 					     SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
98 					     afs_i_init_once);
99 	if (!afs_inode_cachep) {
100 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
101 		return ret;
102 	}
103 
104 	/* now export our filesystem to lesser mortals */
105 	ret = register_filesystem(&afs_fs_type);
106 	if (ret < 0) {
107 		kmem_cache_destroy(afs_inode_cachep);
108 		_leave(" = %d", ret);
109 		return ret;
110 	}
111 
112 	_leave(" = 0");
113 	return 0;
114 }
115 
116 /*
117  * clean up the filesystem
118  */
119 void __exit afs_fs_exit(void)
120 {
121 	_enter("");
122 
123 	afs_mntpt_kill_timer();
124 	unregister_filesystem(&afs_fs_type);
125 
126 	if (atomic_read(&afs_count_active_inodes) != 0) {
127 		printk("kAFS: %d active inode objects still present\n",
128 		       atomic_read(&afs_count_active_inodes));
129 		BUG();
130 	}
131 
132 	/*
133 	 * Make sure all delayed rcu free inodes are flushed before we
134 	 * destroy cache.
135 	 */
136 	rcu_barrier();
137 	kmem_cache_destroy(afs_inode_cachep);
138 	_leave("");
139 }
140 
141 /*
142  * Display the mount device name in /proc/mounts.
143  */
144 static int afs_show_devname(struct seq_file *m, struct dentry *root)
145 {
146 	struct afs_super_info *as = root->d_sb->s_fs_info;
147 	struct afs_volume *volume = as->volume;
148 	struct afs_cell *cell = volume->cell;
149 	const char *suf = "";
150 	char pref = '%';
151 
152 	switch (volume->type) {
153 	case AFSVL_RWVOL:
154 		break;
155 	case AFSVL_ROVOL:
156 		pref = '#';
157 		if (volume->type_force)
158 			suf = ".readonly";
159 		break;
160 	case AFSVL_BACKVOL:
161 		pref = '#';
162 		suf = ".backup";
163 		break;
164 	}
165 
166 	seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->vlocation->vldb.name, suf);
167 	return 0;
168 }
169 
170 /*
171  * Display the mount options in /proc/mounts.
172  */
173 static int afs_show_options(struct seq_file *m, struct dentry *root)
174 {
175 	if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
176 		seq_puts(m, "autocell");
177 	return 0;
178 }
179 
180 /*
181  * parse the mount options
182  * - this function has been shamelessly adapted from the ext3 fs which
183  *   shamelessly adapted it from the msdos fs
184  */
185 static int afs_parse_options(struct afs_mount_params *params,
186 			     char *options, const char **devname)
187 {
188 	struct afs_cell *cell;
189 	substring_t args[MAX_OPT_ARGS];
190 	char *p;
191 	int token;
192 
193 	_enter("%s", options);
194 
195 	options[PAGE_SIZE - 1] = 0;
196 
197 	while ((p = strsep(&options, ","))) {
198 		if (!*p)
199 			continue;
200 
201 		token = match_token(p, afs_options_list, args);
202 		switch (token) {
203 		case afs_opt_cell:
204 			cell = afs_cell_lookup(args[0].from,
205 					       args[0].to - args[0].from,
206 					       false);
207 			if (IS_ERR(cell))
208 				return PTR_ERR(cell);
209 			afs_put_cell(params->cell);
210 			params->cell = cell;
211 			break;
212 
213 		case afs_opt_rwpath:
214 			params->rwpath = 1;
215 			break;
216 
217 		case afs_opt_vol:
218 			*devname = args[0].from;
219 			break;
220 
221 		case afs_opt_autocell:
222 			params->autocell = 1;
223 			break;
224 
225 		default:
226 			printk(KERN_ERR "kAFS:"
227 			       " Unknown or invalid mount option: '%s'\n", p);
228 			return -EINVAL;
229 		}
230 	}
231 
232 	_leave(" = 0");
233 	return 0;
234 }
235 
236 /*
237  * parse a device name to get cell name, volume name, volume type and R/W
238  * selector
239  * - this can be one of the following:
240  *	"%[cell:]volume[.]"		R/W volume
241  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
242  *					 or R/W (rwpath=1) volume
243  *	"%[cell:]volume.readonly"	R/O volume
244  *	"#[cell:]volume.readonly"	R/O volume
245  *	"%[cell:]volume.backup"		Backup volume
246  *	"#[cell:]volume.backup"		Backup volume
247  */
248 static int afs_parse_device_name(struct afs_mount_params *params,
249 				 const char *name)
250 {
251 	struct afs_cell *cell;
252 	const char *cellname, *suffix;
253 	int cellnamesz;
254 
255 	_enter(",%s", name);
256 
257 	if (!name) {
258 		printk(KERN_ERR "kAFS: no volume name specified\n");
259 		return -EINVAL;
260 	}
261 
262 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
263 		printk(KERN_ERR "kAFS: unparsable volume name\n");
264 		return -EINVAL;
265 	}
266 
267 	/* determine the type of volume we're looking for */
268 	params->type = AFSVL_ROVOL;
269 	params->force = false;
270 	if (params->rwpath || name[0] == '%') {
271 		params->type = AFSVL_RWVOL;
272 		params->force = true;
273 	}
274 	name++;
275 
276 	/* split the cell name out if there is one */
277 	params->volname = strchr(name, ':');
278 	if (params->volname) {
279 		cellname = name;
280 		cellnamesz = params->volname - name;
281 		params->volname++;
282 	} else {
283 		params->volname = name;
284 		cellname = NULL;
285 		cellnamesz = 0;
286 	}
287 
288 	/* the volume type is further affected by a possible suffix */
289 	suffix = strrchr(params->volname, '.');
290 	if (suffix) {
291 		if (strcmp(suffix, ".readonly") == 0) {
292 			params->type = AFSVL_ROVOL;
293 			params->force = true;
294 		} else if (strcmp(suffix, ".backup") == 0) {
295 			params->type = AFSVL_BACKVOL;
296 			params->force = true;
297 		} else if (suffix[1] == 0) {
298 		} else {
299 			suffix = NULL;
300 		}
301 	}
302 
303 	params->volnamesz = suffix ?
304 		suffix - params->volname : strlen(params->volname);
305 
306 	_debug("cell %*.*s [%p]",
307 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
308 
309 	/* lookup the cell record */
310 	if (cellname || !params->cell) {
311 		cell = afs_cell_lookup(cellname, cellnamesz, true);
312 		if (IS_ERR(cell)) {
313 			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
314 			       cellnamesz, cellnamesz, cellname ?: "");
315 			return PTR_ERR(cell);
316 		}
317 		afs_put_cell(params->cell);
318 		params->cell = cell;
319 	}
320 
321 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
322 	       params->cell->name, params->cell,
323 	       params->volnamesz, params->volnamesz, params->volname,
324 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
325 
326 	return 0;
327 }
328 
329 /*
330  * check a superblock to see if it's the one we're looking for
331  */
332 static int afs_test_super(struct super_block *sb, void *data)
333 {
334 	struct afs_super_info *as1 = data;
335 	struct afs_super_info *as = sb->s_fs_info;
336 
337 	return as->volume == as1->volume;
338 }
339 
340 static int afs_set_super(struct super_block *sb, void *data)
341 {
342 	sb->s_fs_info = data;
343 	return set_anon_super(sb, NULL);
344 }
345 
346 /*
347  * fill in the superblock
348  */
349 static int afs_fill_super(struct super_block *sb,
350 			  struct afs_mount_params *params)
351 {
352 	struct afs_super_info *as = sb->s_fs_info;
353 	struct afs_fid fid;
354 	struct inode *inode = NULL;
355 	int ret;
356 
357 	_enter("");
358 
359 	/* fill in the superblock */
360 	sb->s_blocksize		= PAGE_SIZE;
361 	sb->s_blocksize_bits	= PAGE_SHIFT;
362 	sb->s_magic		= AFS_FS_MAGIC;
363 	sb->s_op		= &afs_super_ops;
364 	sb->s_xattr		= afs_xattr_handlers;
365 	ret = super_setup_bdi(sb);
366 	if (ret)
367 		return ret;
368 	sb->s_bdi->ra_pages	= VM_MAX_READAHEAD * 1024 / PAGE_SIZE;
369 	strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
370 
371 	/* allocate the root inode and dentry */
372 	fid.vid		= as->volume->vid;
373 	fid.vnode	= 1;
374 	fid.unique	= 1;
375 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
376 	if (IS_ERR(inode))
377 		return PTR_ERR(inode);
378 
379 	if (params->autocell)
380 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
381 
382 	ret = -ENOMEM;
383 	sb->s_root = d_make_root(inode);
384 	if (!sb->s_root)
385 		goto error;
386 
387 	sb->s_d_op = &afs_fs_dentry_operations;
388 
389 	_leave(" = 0");
390 	return 0;
391 
392 error:
393 	_leave(" = %d", ret);
394 	return ret;
395 }
396 
397 /*
398  * get an AFS superblock
399  */
400 static struct dentry *afs_mount(struct file_system_type *fs_type,
401 		      int flags, const char *dev_name, void *options)
402 {
403 	struct afs_mount_params params;
404 	struct super_block *sb;
405 	struct afs_volume *vol;
406 	struct key *key;
407 	char *new_opts = kstrdup(options, GFP_KERNEL);
408 	struct afs_super_info *as;
409 	int ret;
410 
411 	_enter(",,%s,%p", dev_name, options);
412 
413 	memset(&params, 0, sizeof(params));
414 
415 	ret = -EINVAL;
416 	if (current->nsproxy->net_ns != &init_net)
417 		goto error;
418 
419 	/* parse the options and device name */
420 	if (options) {
421 		ret = afs_parse_options(&params, options, &dev_name);
422 		if (ret < 0)
423 			goto error;
424 	}
425 
426 	ret = afs_parse_device_name(&params, dev_name);
427 	if (ret < 0)
428 		goto error;
429 
430 	/* try and do the mount securely */
431 	key = afs_request_key(params.cell);
432 	if (IS_ERR(key)) {
433 		_leave(" = %ld [key]", PTR_ERR(key));
434 		ret = PTR_ERR(key);
435 		goto error;
436 	}
437 	params.key = key;
438 
439 	/* parse the device name */
440 	vol = afs_volume_lookup(&params);
441 	if (IS_ERR(vol)) {
442 		ret = PTR_ERR(vol);
443 		goto error;
444 	}
445 
446 	/* allocate a superblock info record */
447 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
448 	if (!as) {
449 		ret = -ENOMEM;
450 		afs_put_volume(vol);
451 		goto error;
452 	}
453 	as->volume = vol;
454 
455 	/* allocate a deviceless superblock */
456 	sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
457 	if (IS_ERR(sb)) {
458 		ret = PTR_ERR(sb);
459 		afs_put_volume(vol);
460 		kfree(as);
461 		goto error;
462 	}
463 
464 	if (!sb->s_root) {
465 		/* initial superblock/root creation */
466 		_debug("create");
467 		ret = afs_fill_super(sb, &params);
468 		if (ret < 0) {
469 			deactivate_locked_super(sb);
470 			goto error;
471 		}
472 		sb->s_flags |= MS_ACTIVE;
473 	} else {
474 		_debug("reuse");
475 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
476 		afs_put_volume(vol);
477 		kfree(as);
478 	}
479 
480 	afs_put_cell(params.cell);
481 	kfree(new_opts);
482 	_leave(" = 0 [%p]", sb);
483 	return dget(sb->s_root);
484 
485 error:
486 	afs_put_cell(params.cell);
487 	key_put(params.key);
488 	kfree(new_opts);
489 	_leave(" = %d", ret);
490 	return ERR_PTR(ret);
491 }
492 
493 static void afs_kill_super(struct super_block *sb)
494 {
495 	struct afs_super_info *as = sb->s_fs_info;
496 	kill_anon_super(sb);
497 	afs_put_volume(as->volume);
498 	kfree(as);
499 }
500 
501 /*
502  * initialise an inode cache slab element prior to any use
503  */
504 static void afs_i_init_once(void *_vnode)
505 {
506 	struct afs_vnode *vnode = _vnode;
507 
508 	memset(vnode, 0, sizeof(*vnode));
509 	inode_init_once(&vnode->vfs_inode);
510 	init_waitqueue_head(&vnode->update_waitq);
511 	mutex_init(&vnode->permits_lock);
512 	mutex_init(&vnode->validate_lock);
513 	spin_lock_init(&vnode->writeback_lock);
514 	spin_lock_init(&vnode->lock);
515 	INIT_LIST_HEAD(&vnode->writebacks);
516 	INIT_LIST_HEAD(&vnode->pending_locks);
517 	INIT_LIST_HEAD(&vnode->granted_locks);
518 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
519 	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
520 }
521 
522 /*
523  * allocate an AFS inode struct from our slab cache
524  */
525 static struct inode *afs_alloc_inode(struct super_block *sb)
526 {
527 	struct afs_vnode *vnode;
528 
529 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
530 	if (!vnode)
531 		return NULL;
532 
533 	atomic_inc(&afs_count_active_inodes);
534 
535 	memset(&vnode->fid, 0, sizeof(vnode->fid));
536 	memset(&vnode->status, 0, sizeof(vnode->status));
537 
538 	vnode->volume		= NULL;
539 	vnode->update_cnt	= 0;
540 	vnode->flags		= 1 << AFS_VNODE_UNSET;
541 	vnode->cb_promised	= false;
542 
543 	_leave(" = %p", &vnode->vfs_inode);
544 	return &vnode->vfs_inode;
545 }
546 
547 static void afs_i_callback(struct rcu_head *head)
548 {
549 	struct inode *inode = container_of(head, struct inode, i_rcu);
550 	struct afs_vnode *vnode = AFS_FS_I(inode);
551 	kmem_cache_free(afs_inode_cachep, vnode);
552 }
553 
554 /*
555  * destroy an AFS inode struct
556  */
557 static void afs_destroy_inode(struct inode *inode)
558 {
559 	struct afs_vnode *vnode = AFS_FS_I(inode);
560 
561 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
562 
563 	_debug("DESTROY INODE %p", inode);
564 
565 	ASSERTCMP(vnode->server, ==, NULL);
566 
567 	call_rcu(&inode->i_rcu, afs_i_callback);
568 	atomic_dec(&afs_count_active_inodes);
569 }
570 
571 /*
572  * return information about an AFS volume
573  */
574 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
575 {
576 	struct afs_volume_status vs;
577 	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
578 	struct key *key;
579 	int ret;
580 
581 	key = afs_request_key(vnode->volume->cell);
582 	if (IS_ERR(key))
583 		return PTR_ERR(key);
584 
585 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
586 	key_put(key);
587 	if (ret < 0) {
588 		_leave(" = %d", ret);
589 		return ret;
590 	}
591 
592 	buf->f_type	= dentry->d_sb->s_magic;
593 	buf->f_bsize	= AFS_BLOCK_SIZE;
594 	buf->f_namelen	= AFSNAMEMAX - 1;
595 
596 	if (vs.max_quota == 0)
597 		buf->f_blocks = vs.part_max_blocks;
598 	else
599 		buf->f_blocks = vs.max_quota;
600 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
601 	return 0;
602 }
603