xref: /openbmc/linux/fs/afs/super.c (revision 25985edc) 
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 struct inode *afs_alloc_inode(struct super_block *sb);
35 static void afs_put_super(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	= kill_anon_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 	.put_super	= afs_put_super,
54 	.show_options	= generic_show_options,
55 };
56 
57 static struct kmem_cache *afs_inode_cachep;
58 static atomic_t afs_count_active_inodes;
59 
60 enum {
61 	afs_no_opt,
62 	afs_opt_cell,
63 	afs_opt_rwpath,
64 	afs_opt_vol,
65 	afs_opt_autocell,
66 };
67 
68 static const match_table_t afs_options_list = {
69 	{ afs_opt_cell,		"cell=%s"	},
70 	{ afs_opt_rwpath,	"rwpath"	},
71 	{ afs_opt_vol,		"vol=%s"	},
72 	{ afs_opt_autocell,	"autocell"	},
73 	{ afs_no_opt,		NULL		},
74 };
75 
76 /*
77  * initialise the filesystem
78  */
79 int __init afs_fs_init(void)
80 {
81 	int ret;
82 
83 	_enter("");
84 
85 	/* create ourselves an inode cache */
86 	atomic_set(&afs_count_active_inodes, 0);
87 
88 	ret = -ENOMEM;
89 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
90 					     sizeof(struct afs_vnode),
91 					     0,
92 					     SLAB_HWCACHE_ALIGN,
93 					     afs_i_init_once);
94 	if (!afs_inode_cachep) {
95 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
96 		return ret;
97 	}
98 
99 	/* now export our filesystem to lesser mortals */
100 	ret = register_filesystem(&afs_fs_type);
101 	if (ret < 0) {
102 		kmem_cache_destroy(afs_inode_cachep);
103 		_leave(" = %d", ret);
104 		return ret;
105 	}
106 
107 	_leave(" = 0");
108 	return 0;
109 }
110 
111 /*
112  * clean up the filesystem
113  */
114 void __exit afs_fs_exit(void)
115 {
116 	_enter("");
117 
118 	afs_mntpt_kill_timer();
119 	unregister_filesystem(&afs_fs_type);
120 
121 	if (atomic_read(&afs_count_active_inodes) != 0) {
122 		printk("kAFS: %d active inode objects still present\n",
123 		       atomic_read(&afs_count_active_inodes));
124 		BUG();
125 	}
126 
127 	kmem_cache_destroy(afs_inode_cachep);
128 	_leave("");
129 }
130 
131 /*
132  * parse the mount options
133  * - this function has been shamelessly adapted from the ext3 fs which
134  *   shamelessly adapted it from the msdos fs
135  */
136 static int afs_parse_options(struct afs_mount_params *params,
137 			     char *options, const char **devname)
138 {
139 	struct afs_cell *cell;
140 	substring_t args[MAX_OPT_ARGS];
141 	char *p;
142 	int token;
143 
144 	_enter("%s", options);
145 
146 	options[PAGE_SIZE - 1] = 0;
147 
148 	while ((p = strsep(&options, ","))) {
149 		if (!*p)
150 			continue;
151 
152 		token = match_token(p, afs_options_list, args);
153 		switch (token) {
154 		case afs_opt_cell:
155 			cell = afs_cell_lookup(args[0].from,
156 					       args[0].to - args[0].from,
157 					       false);
158 			if (IS_ERR(cell))
159 				return PTR_ERR(cell);
160 			afs_put_cell(params->cell);
161 			params->cell = cell;
162 			break;
163 
164 		case afs_opt_rwpath:
165 			params->rwpath = 1;
166 			break;
167 
168 		case afs_opt_vol:
169 			*devname = args[0].from;
170 			break;
171 
172 		case afs_opt_autocell:
173 			params->autocell = 1;
174 			break;
175 
176 		default:
177 			printk(KERN_ERR "kAFS:"
178 			       " Unknown or invalid mount option: '%s'\n", p);
179 			return -EINVAL;
180 		}
181 	}
182 
183 	_leave(" = 0");
184 	return 0;
185 }
186 
187 /*
188  * parse a device name to get cell name, volume name, volume type and R/W
189  * selector
190  * - this can be one of the following:
191  *	"%[cell:]volume[.]"		R/W volume
192  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
193  *					 or R/W (rwpath=1) volume
194  *	"%[cell:]volume.readonly"	R/O volume
195  *	"#[cell:]volume.readonly"	R/O volume
196  *	"%[cell:]volume.backup"		Backup volume
197  *	"#[cell:]volume.backup"		Backup volume
198  */
199 static int afs_parse_device_name(struct afs_mount_params *params,
200 				 const char *name)
201 {
202 	struct afs_cell *cell;
203 	const char *cellname, *suffix;
204 	int cellnamesz;
205 
206 	_enter(",%s", name);
207 
208 	if (!name) {
209 		printk(KERN_ERR "kAFS: no volume name specified\n");
210 		return -EINVAL;
211 	}
212 
213 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
214 		printk(KERN_ERR "kAFS: unparsable volume name\n");
215 		return -EINVAL;
216 	}
217 
218 	/* determine the type of volume we're looking for */
219 	params->type = AFSVL_ROVOL;
220 	params->force = false;
221 	if (params->rwpath || name[0] == '%') {
222 		params->type = AFSVL_RWVOL;
223 		params->force = true;
224 	}
225 	name++;
226 
227 	/* split the cell name out if there is one */
228 	params->volname = strchr(name, ':');
229 	if (params->volname) {
230 		cellname = name;
231 		cellnamesz = params->volname - name;
232 		params->volname++;
233 	} else {
234 		params->volname = name;
235 		cellname = NULL;
236 		cellnamesz = 0;
237 	}
238 
239 	/* the volume type is further affected by a possible suffix */
240 	suffix = strrchr(params->volname, '.');
241 	if (suffix) {
242 		if (strcmp(suffix, ".readonly") == 0) {
243 			params->type = AFSVL_ROVOL;
244 			params->force = true;
245 		} else if (strcmp(suffix, ".backup") == 0) {
246 			params->type = AFSVL_BACKVOL;
247 			params->force = true;
248 		} else if (suffix[1] == 0) {
249 		} else {
250 			suffix = NULL;
251 		}
252 	}
253 
254 	params->volnamesz = suffix ?
255 		suffix - params->volname : strlen(params->volname);
256 
257 	_debug("cell %*.*s [%p]",
258 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
259 
260 	/* lookup the cell record */
261 	if (cellname || !params->cell) {
262 		cell = afs_cell_lookup(cellname, cellnamesz, true);
263 		if (IS_ERR(cell)) {
264 			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
265 			       cellnamesz, cellnamesz, cellname ?: "");
266 			return PTR_ERR(cell);
267 		}
268 		afs_put_cell(params->cell);
269 		params->cell = cell;
270 	}
271 
272 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
273 	       params->cell->name, params->cell,
274 	       params->volnamesz, params->volnamesz, params->volname,
275 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
276 
277 	return 0;
278 }
279 
280 /*
281  * check a superblock to see if it's the one we're looking for
282  */
283 static int afs_test_super(struct super_block *sb, void *data)
284 {
285 	struct afs_mount_params *params = data;
286 	struct afs_super_info *as = sb->s_fs_info;
287 
288 	return as->volume == params->volume;
289 }
290 
291 /*
292  * fill in the superblock
293  */
294 static int afs_fill_super(struct super_block *sb, void *data)
295 {
296 	struct afs_mount_params *params = data;
297 	struct afs_super_info *as = NULL;
298 	struct afs_fid fid;
299 	struct dentry *root = NULL;
300 	struct inode *inode = NULL;
301 	int ret;
302 
303 	_enter("");
304 
305 	/* allocate a superblock info record */
306 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
307 	if (!as) {
308 		_leave(" = -ENOMEM");
309 		return -ENOMEM;
310 	}
311 
312 	afs_get_volume(params->volume);
313 	as->volume = params->volume;
314 
315 	/* fill in the superblock */
316 	sb->s_blocksize		= PAGE_CACHE_SIZE;
317 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
318 	sb->s_magic		= AFS_FS_MAGIC;
319 	sb->s_op		= &afs_super_ops;
320 	sb->s_fs_info		= as;
321 	sb->s_bdi		= &as->volume->bdi;
322 
323 	/* allocate the root inode and dentry */
324 	fid.vid		= as->volume->vid;
325 	fid.vnode	= 1;
326 	fid.unique	= 1;
327 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
328 	if (IS_ERR(inode))
329 		goto error_inode;
330 
331 	if (params->autocell)
332 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
333 
334 	ret = -ENOMEM;
335 	root = d_alloc_root(inode);
336 	if (!root)
337 		goto error;
338 
339 	sb->s_d_op = &afs_fs_dentry_operations;
340 	sb->s_root = root;
341 
342 	_leave(" = 0");
343 	return 0;
344 
345 error_inode:
346 	ret = PTR_ERR(inode);
347 	inode = NULL;
348 error:
349 	iput(inode);
350 	afs_put_volume(as->volume);
351 	kfree(as);
352 
353 	sb->s_fs_info = NULL;
354 
355 	_leave(" = %d", ret);
356 	return ret;
357 }
358 
359 /*
360  * get an AFS superblock
361  */
362 static struct dentry *afs_mount(struct file_system_type *fs_type,
363 		      int flags, const char *dev_name, void *options)
364 {
365 	struct afs_mount_params params;
366 	struct super_block *sb;
367 	struct afs_volume *vol;
368 	struct key *key;
369 	char *new_opts = kstrdup(options, GFP_KERNEL);
370 	int ret;
371 
372 	_enter(",,%s,%p", dev_name, options);
373 
374 	memset(&params, 0, sizeof(params));
375 
376 	/* parse the options and device name */
377 	if (options) {
378 		ret = afs_parse_options(&params, options, &dev_name);
379 		if (ret < 0)
380 			goto error;
381 	}
382 
383 	ret = afs_parse_device_name(&params, dev_name);
384 	if (ret < 0)
385 		goto error;
386 
387 	/* try and do the mount securely */
388 	key = afs_request_key(params.cell);
389 	if (IS_ERR(key)) {
390 		_leave(" = %ld [key]", PTR_ERR(key));
391 		ret = PTR_ERR(key);
392 		goto error;
393 	}
394 	params.key = key;
395 
396 	/* parse the device name */
397 	vol = afs_volume_lookup(&params);
398 	if (IS_ERR(vol)) {
399 		ret = PTR_ERR(vol);
400 		goto error;
401 	}
402 	params.volume = vol;
403 
404 	/* allocate a deviceless superblock */
405 	sb = sget(fs_type, afs_test_super, set_anon_super, &params);
406 	if (IS_ERR(sb)) {
407 		ret = PTR_ERR(sb);
408 		goto error;
409 	}
410 
411 	if (!sb->s_root) {
412 		/* initial superblock/root creation */
413 		_debug("create");
414 		sb->s_flags = flags;
415 		ret = afs_fill_super(sb, &params);
416 		if (ret < 0) {
417 			deactivate_locked_super(sb);
418 			goto error;
419 		}
420 		save_mount_options(sb, new_opts);
421 		sb->s_flags |= MS_ACTIVE;
422 	} else {
423 		_debug("reuse");
424 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
425 	}
426 
427 	afs_put_volume(params.volume);
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_volume(params.volume);
435 	afs_put_cell(params.cell);
436 	key_put(params.key);
437 	kfree(new_opts);
438 	_leave(" = %d", ret);
439 	return ERR_PTR(ret);
440 }
441 
442 /*
443  * finish the unmounting process on the superblock
444  */
445 static void afs_put_super(struct super_block *sb)
446 {
447 	struct afs_super_info *as = sb->s_fs_info;
448 
449 	_enter("");
450 
451 	afs_put_volume(as->volume);
452 
453 	_leave("");
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 	INIT_LIST_HEAD(&inode->i_dentry);
507 	kmem_cache_free(afs_inode_cachep, vnode);
508 }
509 
510 /*
511  * destroy an AFS inode struct
512  */
513 static void afs_destroy_inode(struct inode *inode)
514 {
515 	struct afs_vnode *vnode = AFS_FS_I(inode);
516 
517 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
518 
519 	_debug("DESTROY INODE %p", inode);
520 
521 	ASSERTCMP(vnode->server, ==, NULL);
522 
523 	call_rcu(&inode->i_rcu, afs_i_callback);
524 	atomic_dec(&afs_count_active_inodes);
525 }
526 
527 /*
528  * return information about an AFS volume
529  */
530 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
531 {
532 	struct afs_volume_status vs;
533 	struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
534 	struct key *key;
535 	int ret;
536 
537 	key = afs_request_key(vnode->volume->cell);
538 	if (IS_ERR(key))
539 		return PTR_ERR(key);
540 
541 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
542 	key_put(key);
543 	if (ret < 0) {
544 		_leave(" = %d", ret);
545 		return ret;
546 	}
547 
548 	buf->f_type	= dentry->d_sb->s_magic;
549 	buf->f_bsize	= AFS_BLOCK_SIZE;
550 	buf->f_namelen	= AFSNAMEMAX - 1;
551 
552 	if (vs.max_quota == 0)
553 		buf->f_blocks = vs.part_max_blocks;
554 	else
555 		buf->f_blocks = vs.max_quota;
556 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
557 	return 0;
558 }
559