xref: /openbmc/linux/fs/afs/super.c (revision c21b37f6) 
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@redhat.com>
14  *
15  */
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/init.h>
20 #include <linux/slab.h>
21 #include <linux/fs.h>
22 #include <linux/pagemap.h>
23 #include <linux/parser.h>
24 #include <linux/statfs.h>
25 #include <linux/sched.h>
26 #include "internal.h"
27 
28 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
29 
30 static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
31 			    unsigned long flags);
32 static int afs_get_sb(struct file_system_type *fs_type,
33 		      int flags, const char *dev_name,
34 		      void *data, struct vfsmount *mnt);
35 static struct inode *afs_alloc_inode(struct super_block *sb);
36 static void afs_put_super(struct super_block *sb);
37 static void afs_destroy_inode(struct inode *inode);
38 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
39 
40 struct file_system_type afs_fs_type = {
41 	.owner		= THIS_MODULE,
42 	.name		= "afs",
43 	.get_sb		= afs_get_sb,
44 	.kill_sb	= kill_anon_super,
45 	.fs_flags	= 0,
46 };
47 
48 static const struct super_operations afs_super_ops = {
49 	.statfs		= afs_statfs,
50 	.alloc_inode	= afs_alloc_inode,
51 	.write_inode	= afs_write_inode,
52 	.destroy_inode	= afs_destroy_inode,
53 	.clear_inode	= afs_clear_inode,
54 	.umount_begin	= afs_umount_begin,
55 	.put_super	= afs_put_super,
56 };
57 
58 static struct kmem_cache *afs_inode_cachep;
59 static atomic_t afs_count_active_inodes;
60 
61 enum {
62 	afs_no_opt,
63 	afs_opt_cell,
64 	afs_opt_rwpath,
65 	afs_opt_vol,
66 };
67 
68 static 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_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 			if (IS_ERR(cell))
157 				return PTR_ERR(cell);
158 			afs_put_cell(params->cell);
159 			params->cell = cell;
160 			break;
161 
162 		case afs_opt_rwpath:
163 			params->rwpath = 1;
164 			break;
165 
166 		case afs_opt_vol:
167 			*devname = args[0].from;
168 			break;
169 
170 		default:
171 			printk(KERN_ERR "kAFS:"
172 			       " Unknown or invalid mount option: '%s'\n", p);
173 			return -EINVAL;
174 		}
175 	}
176 
177 	_leave(" = 0");
178 	return 0;
179 }
180 
181 /*
182  * parse a device name to get cell name, volume name, volume type and R/W
183  * selector
184  * - this can be one of the following:
185  *	"%[cell:]volume[.]"		R/W volume
186  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
187  *					 or R/W (rwpath=1) volume
188  *	"%[cell:]volume.readonly"	R/O volume
189  *	"#[cell:]volume.readonly"	R/O volume
190  *	"%[cell:]volume.backup"		Backup volume
191  *	"#[cell:]volume.backup"		Backup volume
192  */
193 static int afs_parse_device_name(struct afs_mount_params *params,
194 				 const char *name)
195 {
196 	struct afs_cell *cell;
197 	const char *cellname, *suffix;
198 	int cellnamesz;
199 
200 	_enter(",%s", name);
201 
202 	if (!name) {
203 		printk(KERN_ERR "kAFS: no volume name specified\n");
204 		return -EINVAL;
205 	}
206 
207 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
208 		printk(KERN_ERR "kAFS: unparsable volume name\n");
209 		return -EINVAL;
210 	}
211 
212 	/* determine the type of volume we're looking for */
213 	params->type = AFSVL_ROVOL;
214 	params->force = false;
215 	if (params->rwpath || name[0] == '%') {
216 		params->type = AFSVL_RWVOL;
217 		params->force = true;
218 	}
219 	name++;
220 
221 	/* split the cell name out if there is one */
222 	params->volname = strchr(name, ':');
223 	if (params->volname) {
224 		cellname = name;
225 		cellnamesz = params->volname - name;
226 		params->volname++;
227 	} else {
228 		params->volname = name;
229 		cellname = NULL;
230 		cellnamesz = 0;
231 	}
232 
233 	/* the volume type is further affected by a possible suffix */
234 	suffix = strrchr(params->volname, '.');
235 	if (suffix) {
236 		if (strcmp(suffix, ".readonly") == 0) {
237 			params->type = AFSVL_ROVOL;
238 			params->force = true;
239 		} else if (strcmp(suffix, ".backup") == 0) {
240 			params->type = AFSVL_BACKVOL;
241 			params->force = true;
242 		} else if (suffix[1] == 0) {
243 		} else {
244 			suffix = NULL;
245 		}
246 	}
247 
248 	params->volnamesz = suffix ?
249 		suffix - params->volname : strlen(params->volname);
250 
251 	_debug("cell %*.*s [%p]",
252 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
253 
254 	/* lookup the cell record */
255 	if (cellname || !params->cell) {
256 		cell = afs_cell_lookup(cellname, cellnamesz);
257 		if (IS_ERR(cell)) {
258 			printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
259 			       cellname ?: "");
260 			return PTR_ERR(cell);
261 		}
262 		afs_put_cell(params->cell);
263 		params->cell = cell;
264 	}
265 
266 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
267 	       params->cell->name, params->cell,
268 	       params->volnamesz, params->volnamesz, params->volname,
269 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
270 
271 	return 0;
272 }
273 
274 /*
275  * check a superblock to see if it's the one we're looking for
276  */
277 static int afs_test_super(struct super_block *sb, void *data)
278 {
279 	struct afs_mount_params *params = data;
280 	struct afs_super_info *as = sb->s_fs_info;
281 
282 	return as->volume == params->volume;
283 }
284 
285 /*
286  * fill in the superblock
287  */
288 static int afs_fill_super(struct super_block *sb, void *data)
289 {
290 	struct afs_mount_params *params = data;
291 	struct afs_super_info *as = NULL;
292 	struct afs_fid fid;
293 	struct dentry *root = NULL;
294 	struct inode *inode = NULL;
295 	int ret;
296 
297 	_enter("");
298 
299 	/* allocate a superblock info record */
300 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
301 	if (!as) {
302 		_leave(" = -ENOMEM");
303 		return -ENOMEM;
304 	}
305 
306 	afs_get_volume(params->volume);
307 	as->volume = params->volume;
308 
309 	/* fill in the superblock */
310 	sb->s_blocksize		= PAGE_CACHE_SIZE;
311 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
312 	sb->s_magic		= AFS_FS_MAGIC;
313 	sb->s_op		= &afs_super_ops;
314 	sb->s_fs_info		= as;
315 
316 	/* allocate the root inode and dentry */
317 	fid.vid		= as->volume->vid;
318 	fid.vnode	= 1;
319 	fid.unique	= 1;
320 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
321 	if (IS_ERR(inode))
322 		goto error_inode;
323 
324 	ret = -ENOMEM;
325 	root = d_alloc_root(inode);
326 	if (!root)
327 		goto error;
328 
329 	sb->s_root = root;
330 
331 	_leave(" = 0");
332 	return 0;
333 
334 error_inode:
335 	ret = PTR_ERR(inode);
336 	inode = NULL;
337 error:
338 	iput(inode);
339 	afs_put_volume(as->volume);
340 	kfree(as);
341 
342 	sb->s_fs_info = NULL;
343 
344 	_leave(" = %d", ret);
345 	return ret;
346 }
347 
348 /*
349  * get an AFS superblock
350  */
351 static int afs_get_sb(struct file_system_type *fs_type,
352 		      int flags,
353 		      const char *dev_name,
354 		      void *options,
355 		      struct vfsmount *mnt)
356 {
357 	struct afs_mount_params params;
358 	struct super_block *sb;
359 	struct afs_volume *vol;
360 	struct key *key;
361 	int ret;
362 
363 	_enter(",,%s,%p", dev_name, options);
364 
365 	memset(&params, 0, sizeof(params));
366 
367 	/* parse the options and device name */
368 	if (options) {
369 		ret = afs_parse_options(&params, options, &dev_name);
370 		if (ret < 0)
371 			goto error;
372 	}
373 
374 	ret = afs_parse_device_name(&params, dev_name);
375 	if (ret < 0)
376 		goto error;
377 
378 	/* try and do the mount securely */
379 	key = afs_request_key(params.cell);
380 	if (IS_ERR(key)) {
381 		_leave(" = %ld [key]", PTR_ERR(key));
382 		ret = PTR_ERR(key);
383 		goto error;
384 	}
385 	params.key = key;
386 
387 	/* parse the device name */
388 	vol = afs_volume_lookup(&params);
389 	if (IS_ERR(vol)) {
390 		ret = PTR_ERR(vol);
391 		goto error;
392 	}
393 	params.volume = vol;
394 
395 	/* allocate a deviceless superblock */
396 	sb = sget(fs_type, afs_test_super, set_anon_super, &params);
397 	if (IS_ERR(sb)) {
398 		ret = PTR_ERR(sb);
399 		goto error;
400 	}
401 
402 	if (!sb->s_root) {
403 		/* initial superblock/root creation */
404 		_debug("create");
405 		sb->s_flags = flags;
406 		ret = afs_fill_super(sb, &params);
407 		if (ret < 0) {
408 			up_write(&sb->s_umount);
409 			deactivate_super(sb);
410 			goto error;
411 		}
412 		sb->s_flags |= MS_ACTIVE;
413 	} else {
414 		_debug("reuse");
415 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
416 	}
417 
418 	simple_set_mnt(mnt, sb);
419 	afs_put_volume(params.volume);
420 	afs_put_cell(params.cell);
421 	_leave(" = 0 [%p]", sb);
422 	return 0;
423 
424 error:
425 	afs_put_volume(params.volume);
426 	afs_put_cell(params.cell);
427 	key_put(params.key);
428 	_leave(" = %d", ret);
429 	return ret;
430 }
431 
432 /*
433  * finish the unmounting process on the superblock
434  */
435 static void afs_put_super(struct super_block *sb)
436 {
437 	struct afs_super_info *as = sb->s_fs_info;
438 
439 	_enter("");
440 
441 	afs_put_volume(as->volume);
442 
443 	_leave("");
444 }
445 
446 /*
447  * initialise an inode cache slab element prior to any use
448  */
449 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
450 			    unsigned long flags)
451 {
452 	struct afs_vnode *vnode = _vnode;
453 
454 	memset(vnode, 0, sizeof(*vnode));
455 	inode_init_once(&vnode->vfs_inode);
456 	init_waitqueue_head(&vnode->update_waitq);
457 	mutex_init(&vnode->permits_lock);
458 	mutex_init(&vnode->validate_lock);
459 	spin_lock_init(&vnode->writeback_lock);
460 	spin_lock_init(&vnode->lock);
461 	INIT_LIST_HEAD(&vnode->writebacks);
462 	INIT_LIST_HEAD(&vnode->pending_locks);
463 	INIT_LIST_HEAD(&vnode->granted_locks);
464 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
465 	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
466 }
467 
468 /*
469  * allocate an AFS inode struct from our slab cache
470  */
471 static struct inode *afs_alloc_inode(struct super_block *sb)
472 {
473 	struct afs_vnode *vnode;
474 
475 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
476 	if (!vnode)
477 		return NULL;
478 
479 	atomic_inc(&afs_count_active_inodes);
480 
481 	memset(&vnode->fid, 0, sizeof(vnode->fid));
482 	memset(&vnode->status, 0, sizeof(vnode->status));
483 
484 	vnode->volume		= NULL;
485 	vnode->update_cnt	= 0;
486 	vnode->flags		= 1 << AFS_VNODE_UNSET;
487 	vnode->cb_promised	= false;
488 
489 	_leave(" = %p", &vnode->vfs_inode);
490 	return &vnode->vfs_inode;
491 }
492 
493 /*
494  * destroy an AFS inode struct
495  */
496 static void afs_destroy_inode(struct inode *inode)
497 {
498 	struct afs_vnode *vnode = AFS_FS_I(inode);
499 
500 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
501 
502 	_debug("DESTROY INODE %p", inode);
503 
504 	ASSERTCMP(vnode->server, ==, NULL);
505 
506 	kmem_cache_free(afs_inode_cachep, vnode);
507 	atomic_dec(&afs_count_active_inodes);
508 }
509 
510 /*
511  * return information about an AFS volume
512  */
513 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
514 {
515 	struct afs_volume_status vs;
516 	struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
517 	struct key *key;
518 	int ret;
519 
520 	key = afs_request_key(vnode->volume->cell);
521 	if (IS_ERR(key))
522 		return PTR_ERR(key);
523 
524 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
525 	key_put(key);
526 	if (ret < 0) {
527 		_leave(" = %d", ret);
528 		return ret;
529 	}
530 
531 	buf->f_type	= dentry->d_sb->s_magic;
532 	buf->f_bsize	= AFS_BLOCK_SIZE;
533 	buf->f_namelen	= AFSNAMEMAX - 1;
534 
535 	if (vs.max_quota == 0)
536 		buf->f_blocks = vs.part_max_blocks;
537 	else
538 		buf->f_blocks = vs.max_quota;
539 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
540 	return 0;
541 }
542