xref: /openbmc/linux/fs/afs/super.c (revision 8569c914) 
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/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);
31 static int afs_get_sb(struct file_system_type *fs_type,
32 		      int flags, const char *dev_name,
33 		      void *data, struct vfsmount *mnt);
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 	.get_sb		= afs_get_sb,
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 	.write_inode	= afs_write_inode,
51 	.destroy_inode	= afs_destroy_inode,
52 	.clear_inode	= afs_clear_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 };
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_no_opt,		NULL		},
72 };
73 
74 /*
75  * initialise the filesystem
76  */
77 int __init afs_fs_init(void)
78 {
79 	int ret;
80 
81 	_enter("");
82 
83 	/* create ourselves an inode cache */
84 	atomic_set(&afs_count_active_inodes, 0);
85 
86 	ret = -ENOMEM;
87 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
88 					     sizeof(struct afs_vnode),
89 					     0,
90 					     SLAB_HWCACHE_ALIGN,
91 					     afs_i_init_once);
92 	if (!afs_inode_cachep) {
93 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
94 		return ret;
95 	}
96 
97 	/* now export our filesystem to lesser mortals */
98 	ret = register_filesystem(&afs_fs_type);
99 	if (ret < 0) {
100 		kmem_cache_destroy(afs_inode_cachep);
101 		_leave(" = %d", ret);
102 		return ret;
103 	}
104 
105 	_leave(" = 0");
106 	return 0;
107 }
108 
109 /*
110  * clean up the filesystem
111  */
112 void __exit afs_fs_exit(void)
113 {
114 	_enter("");
115 
116 	afs_mntpt_kill_timer();
117 	unregister_filesystem(&afs_fs_type);
118 
119 	if (atomic_read(&afs_count_active_inodes) != 0) {
120 		printk("kAFS: %d active inode objects still present\n",
121 		       atomic_read(&afs_count_active_inodes));
122 		BUG();
123 	}
124 
125 	kmem_cache_destroy(afs_inode_cachep);
126 	_leave("");
127 }
128 
129 /*
130  * parse the mount options
131  * - this function has been shamelessly adapted from the ext3 fs which
132  *   shamelessly adapted it from the msdos fs
133  */
134 static int afs_parse_options(struct afs_mount_params *params,
135 			     char *options, const char **devname)
136 {
137 	struct afs_cell *cell;
138 	substring_t args[MAX_OPT_ARGS];
139 	char *p;
140 	int token;
141 
142 	_enter("%s", options);
143 
144 	options[PAGE_SIZE - 1] = 0;
145 
146 	while ((p = strsep(&options, ","))) {
147 		if (!*p)
148 			continue;
149 
150 		token = match_token(p, afs_options_list, args);
151 		switch (token) {
152 		case afs_opt_cell:
153 			cell = afs_cell_lookup(args[0].from,
154 					       args[0].to - args[0].from);
155 			if (IS_ERR(cell))
156 				return PTR_ERR(cell);
157 			afs_put_cell(params->cell);
158 			params->cell = cell;
159 			break;
160 
161 		case afs_opt_rwpath:
162 			params->rwpath = 1;
163 			break;
164 
165 		case afs_opt_vol:
166 			*devname = args[0].from;
167 			break;
168 
169 		default:
170 			printk(KERN_ERR "kAFS:"
171 			       " Unknown or invalid mount option: '%s'\n", p);
172 			return -EINVAL;
173 		}
174 	}
175 
176 	_leave(" = 0");
177 	return 0;
178 }
179 
180 /*
181  * parse a device name to get cell name, volume name, volume type and R/W
182  * selector
183  * - this can be one of the following:
184  *	"%[cell:]volume[.]"		R/W volume
185  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
186  *					 or R/W (rwpath=1) volume
187  *	"%[cell:]volume.readonly"	R/O volume
188  *	"#[cell:]volume.readonly"	R/O volume
189  *	"%[cell:]volume.backup"		Backup volume
190  *	"#[cell:]volume.backup"		Backup volume
191  */
192 static int afs_parse_device_name(struct afs_mount_params *params,
193 				 const char *name)
194 {
195 	struct afs_cell *cell;
196 	const char *cellname, *suffix;
197 	int cellnamesz;
198 
199 	_enter(",%s", name);
200 
201 	if (!name) {
202 		printk(KERN_ERR "kAFS: no volume name specified\n");
203 		return -EINVAL;
204 	}
205 
206 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
207 		printk(KERN_ERR "kAFS: unparsable volume name\n");
208 		return -EINVAL;
209 	}
210 
211 	/* determine the type of volume we're looking for */
212 	params->type = AFSVL_ROVOL;
213 	params->force = false;
214 	if (params->rwpath || name[0] == '%') {
215 		params->type = AFSVL_RWVOL;
216 		params->force = true;
217 	}
218 	name++;
219 
220 	/* split the cell name out if there is one */
221 	params->volname = strchr(name, ':');
222 	if (params->volname) {
223 		cellname = name;
224 		cellnamesz = params->volname - name;
225 		params->volname++;
226 	} else {
227 		params->volname = name;
228 		cellname = NULL;
229 		cellnamesz = 0;
230 	}
231 
232 	/* the volume type is further affected by a possible suffix */
233 	suffix = strrchr(params->volname, '.');
234 	if (suffix) {
235 		if (strcmp(suffix, ".readonly") == 0) {
236 			params->type = AFSVL_ROVOL;
237 			params->force = true;
238 		} else if (strcmp(suffix, ".backup") == 0) {
239 			params->type = AFSVL_BACKVOL;
240 			params->force = true;
241 		} else if (suffix[1] == 0) {
242 		} else {
243 			suffix = NULL;
244 		}
245 	}
246 
247 	params->volnamesz = suffix ?
248 		suffix - params->volname : strlen(params->volname);
249 
250 	_debug("cell %*.*s [%p]",
251 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
252 
253 	/* lookup the cell record */
254 	if (cellname || !params->cell) {
255 		cell = afs_cell_lookup(cellname, cellnamesz);
256 		if (IS_ERR(cell)) {
257 			printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
258 			       cellname ?: "");
259 			return PTR_ERR(cell);
260 		}
261 		afs_put_cell(params->cell);
262 		params->cell = cell;
263 	}
264 
265 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
266 	       params->cell->name, params->cell,
267 	       params->volnamesz, params->volnamesz, params->volname,
268 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
269 
270 	return 0;
271 }
272 
273 /*
274  * check a superblock to see if it's the one we're looking for
275  */
276 static int afs_test_super(struct super_block *sb, void *data)
277 {
278 	struct afs_mount_params *params = data;
279 	struct afs_super_info *as = sb->s_fs_info;
280 
281 	return as->volume == params->volume;
282 }
283 
284 /*
285  * fill in the superblock
286  */
287 static int afs_fill_super(struct super_block *sb, void *data)
288 {
289 	struct afs_mount_params *params = data;
290 	struct afs_super_info *as = NULL;
291 	struct afs_fid fid;
292 	struct dentry *root = NULL;
293 	struct inode *inode = NULL;
294 	int ret;
295 
296 	_enter("");
297 
298 	/* allocate a superblock info record */
299 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
300 	if (!as) {
301 		_leave(" = -ENOMEM");
302 		return -ENOMEM;
303 	}
304 
305 	afs_get_volume(params->volume);
306 	as->volume = params->volume;
307 
308 	/* fill in the superblock */
309 	sb->s_blocksize		= PAGE_CACHE_SIZE;
310 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
311 	sb->s_magic		= AFS_FS_MAGIC;
312 	sb->s_op		= &afs_super_ops;
313 	sb->s_fs_info		= as;
314 
315 	/* allocate the root inode and dentry */
316 	fid.vid		= as->volume->vid;
317 	fid.vnode	= 1;
318 	fid.unique	= 1;
319 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
320 	if (IS_ERR(inode))
321 		goto error_inode;
322 
323 	ret = -ENOMEM;
324 	root = d_alloc_root(inode);
325 	if (!root)
326 		goto error;
327 
328 	sb->s_root = root;
329 
330 	_leave(" = 0");
331 	return 0;
332 
333 error_inode:
334 	ret = PTR_ERR(inode);
335 	inode = NULL;
336 error:
337 	iput(inode);
338 	afs_put_volume(as->volume);
339 	kfree(as);
340 
341 	sb->s_fs_info = NULL;
342 
343 	_leave(" = %d", ret);
344 	return ret;
345 }
346 
347 /*
348  * get an AFS superblock
349  */
350 static int afs_get_sb(struct file_system_type *fs_type,
351 		      int flags,
352 		      const char *dev_name,
353 		      void *options,
354 		      struct vfsmount *mnt)
355 {
356 	struct afs_mount_params params;
357 	struct super_block *sb;
358 	struct afs_volume *vol;
359 	struct key *key;
360 	char *new_opts = kstrdup(options, GFP_KERNEL);
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_options = new_opts;
413 		sb->s_flags |= MS_ACTIVE;
414 	} else {
415 		_debug("reuse");
416 		kfree(new_opts);
417 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
418 	}
419 
420 	simple_set_mnt(mnt, sb);
421 	afs_put_volume(params.volume);
422 	afs_put_cell(params.cell);
423 	_leave(" = 0 [%p]", sb);
424 	return 0;
425 
426 error:
427 	afs_put_volume(params.volume);
428 	afs_put_cell(params.cell);
429 	key_put(params.key);
430 	kfree(new_opts);
431 	_leave(" = %d", ret);
432 	return ret;
433 }
434 
435 /*
436  * finish the unmounting process on the superblock
437  */
438 static void afs_put_super(struct super_block *sb)
439 {
440 	struct afs_super_info *as = sb->s_fs_info;
441 
442 	_enter("");
443 
444 	afs_put_volume(as->volume);
445 
446 	_leave("");
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 /*
496  * destroy an AFS inode struct
497  */
498 static void afs_destroy_inode(struct inode *inode)
499 {
500 	struct afs_vnode *vnode = AFS_FS_I(inode);
501 
502 	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
503 
504 	_debug("DESTROY INODE %p", inode);
505 
506 	ASSERTCMP(vnode->server, ==, NULL);
507 
508 	kmem_cache_free(afs_inode_cachep, vnode);
509 	atomic_dec(&afs_count_active_inodes);
510 }
511 
512 /*
513  * return information about an AFS volume
514  */
515 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
516 {
517 	struct afs_volume_status vs;
518 	struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
519 	struct key *key;
520 	int ret;
521 
522 	key = afs_request_key(vnode->volume->cell);
523 	if (IS_ERR(key))
524 		return PTR_ERR(key);
525 
526 	ret = afs_vnode_get_volume_status(vnode, key, &vs);
527 	key_put(key);
528 	if (ret < 0) {
529 		_leave(" = %d", ret);
530 		return ret;
531 	}
532 
533 	buf->f_type	= dentry->d_sb->s_magic;
534 	buf->f_bsize	= AFS_BLOCK_SIZE;
535 	buf->f_namelen	= AFSNAMEMAX - 1;
536 
537 	if (vs.max_quota == 0)
538 		buf->f_blocks = vs.part_max_blocks;
539 	else
540 		buf->f_blocks = vs.max_quota;
541 	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
542 	return 0;
543 }
544