xref: /openbmc/linux/fs/afs/super.c (revision 3b64b188) 
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 "internal.h"
28 
29 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
30 
31 static void afs_i_init_once(void *foo);
32 static struct dentry *afs_mount(struct file_system_type *fs_type,
33 		      int flags, const char *dev_name, void *data);
34 static void afs_kill_super(struct super_block *sb);
35 static struct inode *afs_alloc_inode(struct super_block *sb);
36 static void afs_destroy_inode(struct inode *inode);
37 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
38 
39 struct file_system_type afs_fs_type = {
40 	.owner		= THIS_MODULE,
41 	.name		= "afs",
42 	.mount		= afs_mount,
43 	.kill_sb	= afs_kill_super,
44 	.fs_flags	= 0,
45 };
46 
47 static const struct super_operations afs_super_ops = {
48 	.statfs		= afs_statfs,
49 	.alloc_inode	= afs_alloc_inode,
50 	.drop_inode	= afs_drop_inode,
51 	.destroy_inode	= afs_destroy_inode,
52 	.evict_inode	= afs_evict_inode,
53 	.show_options	= generic_show_options,
54 };
55 
56 static struct kmem_cache *afs_inode_cachep;
57 static atomic_t afs_count_active_inodes;
58 
59 enum {
60 	afs_no_opt,
61 	afs_opt_cell,
62 	afs_opt_rwpath,
63 	afs_opt_vol,
64 	afs_opt_autocell,
65 };
66 
67 static const match_table_t afs_options_list = {
68 	{ afs_opt_cell,		"cell=%s"	},
69 	{ afs_opt_rwpath,	"rwpath"	},
70 	{ afs_opt_vol,		"vol=%s"	},
71 	{ afs_opt_autocell,	"autocell"	},
72 	{ afs_no_opt,		NULL		},
73 };
74 
75 /*
76  * initialise the filesystem
77  */
78 int __init afs_fs_init(void)
79 {
80 	int ret;
81 
82 	_enter("");
83 
84 	/* create ourselves an inode cache */
85 	atomic_set(&afs_count_active_inodes, 0);
86 
87 	ret = -ENOMEM;
88 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
89 					     sizeof(struct afs_vnode),
90 					     0,
91 					     SLAB_HWCACHE_ALIGN,
92 					     afs_i_init_once);
93 	if (!afs_inode_cachep) {
94 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
95 		return ret;
96 	}
97 
98 	/* now export our filesystem to lesser mortals */
99 	ret = register_filesystem(&afs_fs_type);
100 	if (ret < 0) {
101 		kmem_cache_destroy(afs_inode_cachep);
102 		_leave(" = %d", ret);
103 		return ret;
104 	}
105 
106 	_leave(" = 0");
107 	return 0;
108 }
109 
110 /*
111  * clean up the filesystem
112  */
113 void __exit afs_fs_exit(void)
114 {
115 	_enter("");
116 
117 	afs_mntpt_kill_timer();
118 	unregister_filesystem(&afs_fs_type);
119 
120 	if (atomic_read(&afs_count_active_inodes) != 0) {
121 		printk("kAFS: %d active inode objects still present\n",
122 		       atomic_read(&afs_count_active_inodes));
123 		BUG();
124 	}
125 
126 	/*
127 	 * Make sure all delayed rcu free inodes are flushed before we
128 	 * destroy cache.
129 	 */
130 	rcu_barrier();
131 	kmem_cache_destroy(afs_inode_cachep);
132 	_leave("");
133 }
134 
135 /*
136  * parse the mount options
137  * - this function has been shamelessly adapted from the ext3 fs which
138  *   shamelessly adapted it from the msdos fs
139  */
140 static int afs_parse_options(struct afs_mount_params *params,
141 			     char *options, const char **devname)
142 {
143 	struct afs_cell *cell;
144 	substring_t args[MAX_OPT_ARGS];
145 	char *p;
146 	int token;
147 
148 	_enter("%s", options);
149 
150 	options[PAGE_SIZE - 1] = 0;
151 
152 	while ((p = strsep(&options, ","))) {
153 		if (!*p)
154 			continue;
155 
156 		token = match_token(p, afs_options_list, args);
157 		switch (token) {
158 		case afs_opt_cell:
159 			cell = afs_cell_lookup(args[0].from,
160 					       args[0].to - args[0].from,
161 					       false);
162 			if (IS_ERR(cell))
163 				return PTR_ERR(cell);
164 			afs_put_cell(params->cell);
165 			params->cell = cell;
166 			break;
167 
168 		case afs_opt_rwpath:
169 			params->rwpath = 1;
170 			break;
171 
172 		case afs_opt_vol:
173 			*devname = args[0].from;
174 			break;
175 
176 		case afs_opt_autocell:
177 			params->autocell = 1;
178 			break;
179 
180 		default:
181 			printk(KERN_ERR "kAFS:"
182 			       " Unknown or invalid mount option: '%s'\n", p);
183 			return -EINVAL;
184 		}
185 	}
186 
187 	_leave(" = 0");
188 	return 0;
189 }
190 
191 /*
192  * parse a device name to get cell name, volume name, volume type and R/W
193  * selector
194  * - this can be one of the following:
195  *	"%[cell:]volume[.]"		R/W volume
196  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
197  *					 or R/W (rwpath=1) volume
198  *	"%[cell:]volume.readonly"	R/O volume
199  *	"#[cell:]volume.readonly"	R/O volume
200  *	"%[cell:]volume.backup"		Backup volume
201  *	"#[cell:]volume.backup"		Backup volume
202  */
203 static int afs_parse_device_name(struct afs_mount_params *params,
204 				 const char *name)
205 {
206 	struct afs_cell *cell;
207 	const char *cellname, *suffix;
208 	int cellnamesz;
209 
210 	_enter(",%s", name);
211 
212 	if (!name) {
213 		printk(KERN_ERR "kAFS: no volume name specified\n");
214 		return -EINVAL;
215 	}
216 
217 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
218 		printk(KERN_ERR "kAFS: unparsable volume name\n");
219 		return -EINVAL;
220 	}
221 
222 	/* determine the type of volume we're looking for */
223 	params->type = AFSVL_ROVOL;
224 	params->force = false;
225 	if (params->rwpath || name[0] == '%') {
226 		params->type = AFSVL_RWVOL;
227 		params->force = true;
228 	}
229 	name++;
230 
231 	/* split the cell name out if there is one */
232 	params->volname = strchr(name, ':');
233 	if (params->volname) {
234 		cellname = name;
235 		cellnamesz = params->volname - name;
236 		params->volname++;
237 	} else {
238 		params->volname = name;
239 		cellname = NULL;
240 		cellnamesz = 0;
241 	}
242 
243 	/* the volume type is further affected by a possible suffix */
244 	suffix = strrchr(params->volname, '.');
245 	if (suffix) {
246 		if (strcmp(suffix, ".readonly") == 0) {
247 			params->type = AFSVL_ROVOL;
248 			params->force = true;
249 		} else if (strcmp(suffix, ".backup") == 0) {
250 			params->type = AFSVL_BACKVOL;
251 			params->force = true;
252 		} else if (suffix[1] == 0) {
253 		} else {
254 			suffix = NULL;
255 		}
256 	}
257 
258 	params->volnamesz = suffix ?
259 		suffix - params->volname : strlen(params->volname);
260 
261 	_debug("cell %*.*s [%p]",
262 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
263 
264 	/* lookup the cell record */
265 	if (cellname || !params->cell) {
266 		cell = afs_cell_lookup(cellname, cellnamesz, true);
267 		if (IS_ERR(cell)) {
268 			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
269 			       cellnamesz, cellnamesz, cellname ?: "");
270 			return PTR_ERR(cell);
271 		}
272 		afs_put_cell(params->cell);
273 		params->cell = cell;
274 	}
275 
276 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
277 	       params->cell->name, params->cell,
278 	       params->volnamesz, params->volnamesz, params->volname,
279 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
280 
281 	return 0;
282 }
283 
284 /*
285  * check a superblock to see if it's the one we're looking for
286  */
287 static int afs_test_super(struct super_block *sb, void *data)
288 {
289 	struct afs_super_info *as1 = data;
290 	struct afs_super_info *as = sb->s_fs_info;
291 
292 	return as->volume == as1->volume;
293 }
294 
295 static int afs_set_super(struct super_block *sb, void *data)
296 {
297 	sb->s_fs_info = data;
298 	return set_anon_super(sb, NULL);
299 }
300 
301 /*
302  * fill in the superblock
303  */
304 static int afs_fill_super(struct super_block *sb,
305 			  struct afs_mount_params *params)
306 {
307 	struct afs_super_info *as = sb->s_fs_info;
308 	struct afs_fid fid;
309 	struct inode *inode = NULL;
310 	int ret;
311 
312 	_enter("");
313 
314 	/* fill in the superblock */
315 	sb->s_blocksize		= PAGE_CACHE_SIZE;
316 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
317 	sb->s_magic		= AFS_FS_MAGIC;
318 	sb->s_op		= &afs_super_ops;
319 	sb->s_bdi		= &as->volume->bdi;
320 	strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
321 
322 	/* allocate the root inode and dentry */
323 	fid.vid		= as->volume->vid;
324 	fid.vnode	= 1;
325 	fid.unique	= 1;
326 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
327 	if (IS_ERR(inode))
328 		return PTR_ERR(inode);
329 
330 	if (params->autocell)
331 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
332 
333 	ret = -ENOMEM;
334 	sb->s_root = d_make_root(inode);
335 	if (!sb->s_root)
336 		goto error;
337 
338 	sb->s_d_op = &afs_fs_dentry_operations;
339 
340 	_leave(" = 0");
341 	return 0;
342 
343 error:
344 	_leave(" = %d", ret);
345 	return ret;
346 }
347 
348 /*
349  * get an AFS superblock
350  */
351 static struct dentry *afs_mount(struct file_system_type *fs_type,
352 		      int flags, const char *dev_name, void *options)
353 {
354 	struct afs_mount_params params;
355 	struct super_block *sb;
356 	struct afs_volume *vol;
357 	struct key *key;
358 	char *new_opts = kstrdup(options, GFP_KERNEL);
359 	struct afs_super_info *as;
360 	int ret;
361 
362 	_enter(",,%s,%p", dev_name, options);
363 
364 	memset(&params, 0, sizeof(params));
365 
366 	/* parse the options and device name */
367 	if (options) {
368 		ret = afs_parse_options(&params, options, &dev_name);
369 		if (ret < 0)
370 			goto error;
371 	}
372 
373 	ret = afs_parse_device_name(&params, dev_name);
374 	if (ret < 0)
375 		goto error;
376 
377 	/* try and do the mount securely */
378 	key = afs_request_key(params.cell);
379 	if (IS_ERR(key)) {
380 		_leave(" = %ld [key]", PTR_ERR(key));
381 		ret = PTR_ERR(key);
382 		goto error;
383 	}
384 	params.key = key;
385 
386 	/* parse the device name */
387 	vol = afs_volume_lookup(&params);
388 	if (IS_ERR(vol)) {
389 		ret = PTR_ERR(vol);
390 		goto error;
391 	}
392 
393 	/* allocate a superblock info record */
394 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
395 	if (!as) {
396 		ret = -ENOMEM;
397 		afs_put_volume(vol);
398 		goto error;
399 	}
400 	as->volume = vol;
401 
402 	/* allocate a deviceless superblock */
403 	sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
404 	if (IS_ERR(sb)) {
405 		ret = PTR_ERR(sb);
406 		afs_put_volume(vol);
407 		kfree(as);
408 		goto error;
409 	}
410 
411 	if (!sb->s_root) {
412 		/* initial superblock/root creation */
413 		_debug("create");
414 		ret = afs_fill_super(sb, &params);
415 		if (ret < 0) {
416 			deactivate_locked_super(sb);
417 			goto error;
418 		}
419 		save_mount_options(sb, new_opts);
420 		sb->s_flags |= MS_ACTIVE;
421 	} else {
422 		_debug("reuse");
423 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
424 		afs_put_volume(vol);
425 		kfree(as);
426 	}
427 
428 	afs_put_cell(params.cell);
429 	kfree(new_opts);
430 	_leave(" = 0 [%p]", sb);
431 	return dget(sb->s_root);
432 
433 error:
434 	afs_put_cell(params.cell);
435 	key_put(params.key);
436 	kfree(new_opts);
437 	_leave(" = %d", ret);
438 	return ERR_PTR(ret);
439 }
440 
441 static void afs_kill_super(struct super_block *sb)
442 {
443 	struct afs_super_info *as = sb->s_fs_info;
444 	kill_anon_super(sb);
445 	afs_put_volume(as->volume);
446 	kfree(as);
447 }
448 
449 /*
450  * initialise an inode cache slab element prior to any use
451  */
452 static void afs_i_init_once(void *_vnode)
453 {
454 	struct afs_vnode *vnode = _vnode;
455 
456 	memset(vnode, 0, sizeof(*vnode));
457 	inode_init_once(&vnode->vfs_inode);
458 	init_waitqueue_head(&vnode->update_waitq);
459 	mutex_init(&vnode->permits_lock);
460 	mutex_init(&vnode->validate_lock);
461 	spin_lock_init(&vnode->writeback_lock);
462 	spin_lock_init(&vnode->lock);
463 	INIT_LIST_HEAD(&vnode->writebacks);
464 	INIT_LIST_HEAD(&vnode->pending_locks);
465 	INIT_LIST_HEAD(&vnode->granted_locks);
466 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
467 	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
468 }
469 
470 /*
471  * allocate an AFS inode struct from our slab cache
472  */
473 static struct inode *afs_alloc_inode(struct super_block *sb)
474 {
475 	struct afs_vnode *vnode;
476 
477 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
478 	if (!vnode)
479 		return NULL;
480 
481 	atomic_inc(&afs_count_active_inodes);
482 
483 	memset(&vnode->fid, 0, sizeof(vnode->fid));
484 	memset(&vnode->status, 0, sizeof(vnode->status));
485 
486 	vnode->volume		= NULL;
487 	vnode->update_cnt	= 0;
488 	vnode->flags		= 1 << AFS_VNODE_UNSET;
489 	vnode->cb_promised	= false;
490 
491 	_leave(" = %p", &vnode->vfs_inode);
492 	return &vnode->vfs_inode;
493 }
494 
495 static void afs_i_callback(struct rcu_head *head)
496 {
497 	struct inode *inode = container_of(head, struct inode, i_rcu);
498 	struct afs_vnode *vnode = AFS_FS_I(inode);
499 	kmem_cache_free(afs_inode_cachep, vnode);
500 }
501 
502 /*
503  * destroy an AFS inode struct
504  */
505 static void afs_destroy_inode(struct inode *inode)
506 {
507 	struct afs_vnode *vnode = AFS_FS_I(inode);
508 
509 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
510 
511 	_debug("DESTROY INODE %p", inode);
512 
513 	ASSERTCMP(vnode->server, ==, NULL);
514 
515 	call_rcu(&inode->i_rcu, afs_i_callback);
516 	atomic_dec(&afs_count_active_inodes);
517 }
518 
519 /*
520  * return information about an AFS volume
521  */
522 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
523 {
524 	struct afs_volume_status vs;
525 	struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
526 	struct key *key;
527 	int ret;
528 
529 	key = afs_request_key(vnode->volume->cell);
530 	if (IS_ERR(key))
531 		return PTR_ERR(key);
532 
533 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
534 	key_put(key);
535 	if (ret < 0) {
536 		_leave(" = %d", ret);
537 		return ret;
538 	}
539 
540 	buf->f_type	= dentry->d_sb->s_magic;
541 	buf->f_bsize	= AFS_BLOCK_SIZE;
542 	buf->f_namelen	= AFSNAMEMAX - 1;
543 
544 	if (vs.max_quota == 0)
545 		buf->f_blocks = vs.part_max_blocks;
546 	else
547 		buf->f_blocks = vs.max_quota;
548 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
549 	return 0;
550 }
551