xref: /openbmc/linux/fs/afs/super.c (revision 81d67439) 
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 	kmem_cache_destroy(afs_inode_cachep);
127 	_leave("");
128 }
129 
130 /*
131  * parse the mount options
132  * - this function has been shamelessly adapted from the ext3 fs which
133  *   shamelessly adapted it from the msdos fs
134  */
135 static int afs_parse_options(struct afs_mount_params *params,
136 			     char *options, const char **devname)
137 {
138 	struct afs_cell *cell;
139 	substring_t args[MAX_OPT_ARGS];
140 	char *p;
141 	int token;
142 
143 	_enter("%s", options);
144 
145 	options[PAGE_SIZE - 1] = 0;
146 
147 	while ((p = strsep(&options, ","))) {
148 		if (!*p)
149 			continue;
150 
151 		token = match_token(p, afs_options_list, args);
152 		switch (token) {
153 		case afs_opt_cell:
154 			cell = afs_cell_lookup(args[0].from,
155 					       args[0].to - args[0].from,
156 					       false);
157 			if (IS_ERR(cell))
158 				return PTR_ERR(cell);
159 			afs_put_cell(params->cell);
160 			params->cell = cell;
161 			break;
162 
163 		case afs_opt_rwpath:
164 			params->rwpath = 1;
165 			break;
166 
167 		case afs_opt_vol:
168 			*devname = args[0].from;
169 			break;
170 
171 		case afs_opt_autocell:
172 			params->autocell = 1;
173 			break;
174 
175 		default:
176 			printk(KERN_ERR "kAFS:"
177 			       " Unknown or invalid mount option: '%s'\n", p);
178 			return -EINVAL;
179 		}
180 	}
181 
182 	_leave(" = 0");
183 	return 0;
184 }
185 
186 /*
187  * parse a device name to get cell name, volume name, volume type and R/W
188  * selector
189  * - this can be one of the following:
190  *	"%[cell:]volume[.]"		R/W volume
191  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
192  *					 or R/W (rwpath=1) volume
193  *	"%[cell:]volume.readonly"	R/O volume
194  *	"#[cell:]volume.readonly"	R/O volume
195  *	"%[cell:]volume.backup"		Backup volume
196  *	"#[cell:]volume.backup"		Backup volume
197  */
198 static int afs_parse_device_name(struct afs_mount_params *params,
199 				 const char *name)
200 {
201 	struct afs_cell *cell;
202 	const char *cellname, *suffix;
203 	int cellnamesz;
204 
205 	_enter(",%s", name);
206 
207 	if (!name) {
208 		printk(KERN_ERR "kAFS: no volume name specified\n");
209 		return -EINVAL;
210 	}
211 
212 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
213 		printk(KERN_ERR "kAFS: unparsable volume name\n");
214 		return -EINVAL;
215 	}
216 
217 	/* determine the type of volume we're looking for */
218 	params->type = AFSVL_ROVOL;
219 	params->force = false;
220 	if (params->rwpath || name[0] == '%') {
221 		params->type = AFSVL_RWVOL;
222 		params->force = true;
223 	}
224 	name++;
225 
226 	/* split the cell name out if there is one */
227 	params->volname = strchr(name, ':');
228 	if (params->volname) {
229 		cellname = name;
230 		cellnamesz = params->volname - name;
231 		params->volname++;
232 	} else {
233 		params->volname = name;
234 		cellname = NULL;
235 		cellnamesz = 0;
236 	}
237 
238 	/* the volume type is further affected by a possible suffix */
239 	suffix = strrchr(params->volname, '.');
240 	if (suffix) {
241 		if (strcmp(suffix, ".readonly") == 0) {
242 			params->type = AFSVL_ROVOL;
243 			params->force = true;
244 		} else if (strcmp(suffix, ".backup") == 0) {
245 			params->type = AFSVL_BACKVOL;
246 			params->force = true;
247 		} else if (suffix[1] == 0) {
248 		} else {
249 			suffix = NULL;
250 		}
251 	}
252 
253 	params->volnamesz = suffix ?
254 		suffix - params->volname : strlen(params->volname);
255 
256 	_debug("cell %*.*s [%p]",
257 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
258 
259 	/* lookup the cell record */
260 	if (cellname || !params->cell) {
261 		cell = afs_cell_lookup(cellname, cellnamesz, true);
262 		if (IS_ERR(cell)) {
263 			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
264 			       cellnamesz, cellnamesz, cellname ?: "");
265 			return PTR_ERR(cell);
266 		}
267 		afs_put_cell(params->cell);
268 		params->cell = cell;
269 	}
270 
271 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
272 	       params->cell->name, params->cell,
273 	       params->volnamesz, params->volnamesz, params->volname,
274 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
275 
276 	return 0;
277 }
278 
279 /*
280  * check a superblock to see if it's the one we're looking for
281  */
282 static int afs_test_super(struct super_block *sb, void *data)
283 {
284 	struct afs_super_info *as1 = data;
285 	struct afs_super_info *as = sb->s_fs_info;
286 
287 	return as->volume == as1->volume;
288 }
289 
290 static int afs_set_super(struct super_block *sb, void *data)
291 {
292 	sb->s_fs_info = data;
293 	return set_anon_super(sb, NULL);
294 }
295 
296 /*
297  * fill in the superblock
298  */
299 static int afs_fill_super(struct super_block *sb,
300 			  struct afs_mount_params *params)
301 {
302 	struct afs_super_info *as = sb->s_fs_info;
303 	struct afs_fid fid;
304 	struct dentry *root = NULL;
305 	struct inode *inode = NULL;
306 	int ret;
307 
308 	_enter("");
309 
310 	/* fill in the superblock */
311 	sb->s_blocksize		= PAGE_CACHE_SIZE;
312 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
313 	sb->s_magic		= AFS_FS_MAGIC;
314 	sb->s_op		= &afs_super_ops;
315 	sb->s_bdi		= &as->volume->bdi;
316 	strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
317 
318 	/* allocate the root inode and dentry */
319 	fid.vid		= as->volume->vid;
320 	fid.vnode	= 1;
321 	fid.unique	= 1;
322 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
323 	if (IS_ERR(inode))
324 		return PTR_ERR(inode);
325 
326 	if (params->autocell)
327 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
328 
329 	ret = -ENOMEM;
330 	root = d_alloc_root(inode);
331 	if (!root)
332 		goto error;
333 
334 	sb->s_d_op = &afs_fs_dentry_operations;
335 	sb->s_root = root;
336 
337 	_leave(" = 0");
338 	return 0;
339 
340 error:
341 	iput(inode);
342 	_leave(" = %d", ret);
343 	return ret;
344 }
345 
346 /*
347  * get an AFS superblock
348  */
349 static struct dentry *afs_mount(struct file_system_type *fs_type,
350 		      int flags, const char *dev_name, void *options)
351 {
352 	struct afs_mount_params params;
353 	struct super_block *sb;
354 	struct afs_volume *vol;
355 	struct key *key;
356 	char *new_opts = kstrdup(options, GFP_KERNEL);
357 	struct afs_super_info *as;
358 	int ret;
359 
360 	_enter(",,%s,%p", dev_name, options);
361 
362 	memset(&params, 0, sizeof(params));
363 
364 	/* parse the options and device name */
365 	if (options) {
366 		ret = afs_parse_options(&params, options, &dev_name);
367 		if (ret < 0)
368 			goto error;
369 	}
370 
371 	ret = afs_parse_device_name(&params, dev_name);
372 	if (ret < 0)
373 		goto error;
374 
375 	/* try and do the mount securely */
376 	key = afs_request_key(params.cell);
377 	if (IS_ERR(key)) {
378 		_leave(" = %ld [key]", PTR_ERR(key));
379 		ret = PTR_ERR(key);
380 		goto error;
381 	}
382 	params.key = key;
383 
384 	/* parse the device name */
385 	vol = afs_volume_lookup(&params);
386 	if (IS_ERR(vol)) {
387 		ret = PTR_ERR(vol);
388 		goto error;
389 	}
390 
391 	/* allocate a superblock info record */
392 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
393 	if (!as) {
394 		ret = -ENOMEM;
395 		afs_put_volume(vol);
396 		goto error;
397 	}
398 	as->volume = vol;
399 
400 	/* allocate a deviceless superblock */
401 	sb = sget(fs_type, afs_test_super, afs_set_super, as);
402 	if (IS_ERR(sb)) {
403 		ret = PTR_ERR(sb);
404 		afs_put_volume(vol);
405 		kfree(as);
406 		goto error;
407 	}
408 
409 	if (!sb->s_root) {
410 		/* initial superblock/root creation */
411 		_debug("create");
412 		sb->s_flags = flags;
413 		ret = afs_fill_super(sb, &params);
414 		if (ret < 0) {
415 			deactivate_locked_super(sb);
416 			goto error;
417 		}
418 		save_mount_options(sb, new_opts);
419 		sb->s_flags |= MS_ACTIVE;
420 	} else {
421 		_debug("reuse");
422 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
423 		afs_put_volume(vol);
424 		kfree(as);
425 	}
426 
427 	afs_put_cell(params.cell);
428 	kfree(new_opts);
429 	_leave(" = 0 [%p]", sb);
430 	return dget(sb->s_root);
431 
432 error:
433 	afs_put_cell(params.cell);
434 	key_put(params.key);
435 	kfree(new_opts);
436 	_leave(" = %d", ret);
437 	return ERR_PTR(ret);
438 }
439 
440 static void afs_kill_super(struct super_block *sb)
441 {
442 	struct afs_super_info *as = sb->s_fs_info;
443 	kill_anon_super(sb);
444 	afs_put_volume(as->volume);
445 	kfree(as);
446 }
447 
448 /*
449  * initialise an inode cache slab element prior to any use
450  */
451 static void afs_i_init_once(void *_vnode)
452 {
453 	struct afs_vnode *vnode = _vnode;
454 
455 	memset(vnode, 0, sizeof(*vnode));
456 	inode_init_once(&vnode->vfs_inode);
457 	init_waitqueue_head(&vnode->update_waitq);
458 	mutex_init(&vnode->permits_lock);
459 	mutex_init(&vnode->validate_lock);
460 	spin_lock_init(&vnode->writeback_lock);
461 	spin_lock_init(&vnode->lock);
462 	INIT_LIST_HEAD(&vnode->writebacks);
463 	INIT_LIST_HEAD(&vnode->pending_locks);
464 	INIT_LIST_HEAD(&vnode->granted_locks);
465 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
466 	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
467 }
468 
469 /*
470  * allocate an AFS inode struct from our slab cache
471  */
472 static struct inode *afs_alloc_inode(struct super_block *sb)
473 {
474 	struct afs_vnode *vnode;
475 
476 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
477 	if (!vnode)
478 		return NULL;
479 
480 	atomic_inc(&afs_count_active_inodes);
481 
482 	memset(&vnode->fid, 0, sizeof(vnode->fid));
483 	memset(&vnode->status, 0, sizeof(vnode->status));
484 
485 	vnode->volume		= NULL;
486 	vnode->update_cnt	= 0;
487 	vnode->flags		= 1 << AFS_VNODE_UNSET;
488 	vnode->cb_promised	= false;
489 
490 	_leave(" = %p", &vnode->vfs_inode);
491 	return &vnode->vfs_inode;
492 }
493 
494 static void afs_i_callback(struct rcu_head *head)
495 {
496 	struct inode *inode = container_of(head, struct inode, i_rcu);
497 	struct afs_vnode *vnode = AFS_FS_I(inode);
498 	INIT_LIST_HEAD(&inode->i_dentry);
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