xref: /openbmc/linux/fs/afs/super.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 "internal.h"
26 
27 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
28 
29 static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
30 			    unsigned long flags);
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 	.drop_inode	= generic_delete_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 					     NULL);
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 			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 		default:
172 			printk(KERN_ERR "kAFS:"
173 			       " Unknown or invalid mount option: '%s'\n", p);
174 			return -EINVAL;
175 		}
176 	}
177 
178 	_leave(" = 0");
179 	return 0;
180 }
181 
182 /*
183  * parse a device name to get cell name, volume name, volume type and R/W
184  * selector
185  * - this can be one of the following:
186  *	"%[cell:]volume[.]"		R/W volume
187  *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
188  *					 or R/W (rwpath=1) volume
189  *	"%[cell:]volume.readonly"	R/O volume
190  *	"#[cell:]volume.readonly"	R/O volume
191  *	"%[cell:]volume.backup"		Backup volume
192  *	"#[cell:]volume.backup"		Backup volume
193  */
194 static int afs_parse_device_name(struct afs_mount_params *params,
195 				 const char *name)
196 {
197 	struct afs_cell *cell;
198 	const char *cellname, *suffix;
199 	int cellnamesz;
200 
201 	_enter(",%s", name);
202 
203 	if (!name) {
204 		printk(KERN_ERR "kAFS: no volume name specified\n");
205 		return -EINVAL;
206 	}
207 
208 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
209 		printk(KERN_ERR "kAFS: unparsable volume name\n");
210 		return -EINVAL;
211 	}
212 
213 	/* determine the type of volume we're looking for */
214 	params->type = AFSVL_ROVOL;
215 	params->force = false;
216 	if (params->rwpath || name[0] == '%') {
217 		params->type = AFSVL_RWVOL;
218 		params->force = true;
219 	}
220 	name++;
221 
222 	/* split the cell name out if there is one */
223 	params->volname = strchr(name, ':');
224 	if (params->volname) {
225 		cellname = name;
226 		cellnamesz = params->volname - name;
227 		params->volname++;
228 	} else {
229 		params->volname = name;
230 		cellname = NULL;
231 		cellnamesz = 0;
232 	}
233 
234 	/* the volume type is further affected by a possible suffix */
235 	suffix = strrchr(params->volname, '.');
236 	if (suffix) {
237 		if (strcmp(suffix, ".readonly") == 0) {
238 			params->type = AFSVL_ROVOL;
239 			params->force = true;
240 		} else if (strcmp(suffix, ".backup") == 0) {
241 			params->type = AFSVL_BACKVOL;
242 			params->force = true;
243 		} else if (suffix[1] == 0) {
244 		} else {
245 			suffix = NULL;
246 		}
247 	}
248 
249 	params->volnamesz = suffix ?
250 		suffix - params->volname : strlen(params->volname);
251 
252 	_debug("cell %*.*s [%p]",
253 	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
254 
255 	/* lookup the cell record */
256 	if (cellname || !params->cell) {
257 		cell = afs_cell_lookup(cellname, cellnamesz);
258 		if (IS_ERR(cell)) {
259 			printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
260 			       cellname ?: "");
261 			return PTR_ERR(cell);
262 		}
263 		afs_put_cell(params->cell);
264 		params->cell = cell;
265 	}
266 
267 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
268 	       params->cell->name, params->cell,
269 	       params->volnamesz, params->volnamesz, params->volname,
270 	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
271 
272 	return 0;
273 }
274 
275 /*
276  * check a superblock to see if it's the one we're looking for
277  */
278 static int afs_test_super(struct super_block *sb, void *data)
279 {
280 	struct afs_mount_params *params = data;
281 	struct afs_super_info *as = sb->s_fs_info;
282 
283 	return as->volume == params->volume;
284 }
285 
286 /*
287  * fill in the superblock
288  */
289 static int afs_fill_super(struct super_block *sb, void *data)
290 {
291 	struct afs_mount_params *params = data;
292 	struct afs_super_info *as = NULL;
293 	struct afs_fid fid;
294 	struct dentry *root = NULL;
295 	struct inode *inode = NULL;
296 	int ret;
297 
298 	_enter("");
299 
300 	/* allocate a superblock info record */
301 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
302 	if (!as) {
303 		_leave(" = -ENOMEM");
304 		return -ENOMEM;
305 	}
306 
307 	afs_get_volume(params->volume);
308 	as->volume = params->volume;
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_fs_info		= as;
316 
317 	/* allocate the root inode and dentry */
318 	fid.vid		= as->volume->vid;
319 	fid.vnode	= 1;
320 	fid.unique	= 1;
321 	inode = afs_iget(sb, params->key, &fid, NULL, NULL);
322 	if (IS_ERR(inode))
323 		goto error_inode;
324 
325 	ret = -ENOMEM;
326 	root = d_alloc_root(inode);
327 	if (!root)
328 		goto error;
329 
330 	sb->s_root = root;
331 
332 	_leave(" = 0");
333 	return 0;
334 
335 error_inode:
336 	ret = PTR_ERR(inode);
337 	inode = NULL;
338 error:
339 	iput(inode);
340 	afs_put_volume(as->volume);
341 	kfree(as);
342 
343 	sb->s_fs_info = NULL;
344 
345 	_leave(" = %d", ret);
346 	return ret;
347 }
348 
349 /*
350  * get an AFS superblock
351  */
352 static int afs_get_sb(struct file_system_type *fs_type,
353 		      int flags,
354 		      const char *dev_name,
355 		      void *options,
356 		      struct vfsmount *mnt)
357 {
358 	struct afs_mount_params params;
359 	struct super_block *sb;
360 	struct afs_volume *vol;
361 	struct key *key;
362 	int ret;
363 
364 	_enter(",,%s,%p", dev_name, options);
365 
366 	memset(&params, 0, sizeof(params));
367 
368 	/* parse the options and device name */
369 	if (options) {
370 		ret = afs_parse_options(&params, options, &dev_name);
371 		if (ret < 0)
372 			goto error;
373 	}
374 
375 	ret = afs_parse_device_name(&params, dev_name);
376 	if (ret < 0)
377 		goto error;
378 
379 	/* try and do the mount securely */
380 	key = afs_request_key(params.cell);
381 	if (IS_ERR(key)) {
382 		_leave(" = %ld [key]", PTR_ERR(key));
383 		ret = PTR_ERR(key);
384 		goto error;
385 	}
386 	params.key = key;
387 
388 	/* parse the device name */
389 	vol = afs_volume_lookup(&params);
390 	if (IS_ERR(vol)) {
391 		ret = PTR_ERR(vol);
392 		goto error;
393 	}
394 	params.volume = vol;
395 
396 	/* allocate a deviceless superblock */
397 	sb = sget(fs_type, afs_test_super, set_anon_super, &params);
398 	if (IS_ERR(sb)) {
399 		ret = PTR_ERR(sb);
400 		goto error;
401 	}
402 
403 	if (!sb->s_root) {
404 		/* initial superblock/root creation */
405 		_debug("create");
406 		sb->s_flags = flags;
407 		ret = afs_fill_super(sb, &params);
408 		if (ret < 0) {
409 			up_write(&sb->s_umount);
410 			deactivate_super(sb);
411 			goto error;
412 		}
413 		sb->s_flags |= MS_ACTIVE;
414 	} else {
415 		_debug("reuse");
416 		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
417 	}
418 
419 	simple_set_mnt(mnt, sb);
420 	afs_put_volume(params.volume);
421 	afs_put_cell(params.cell);
422 	_leave(" = 0 [%p]", sb);
423 	return 0;
424 
425 error:
426 	afs_put_volume(params.volume);
427 	afs_put_cell(params.cell);
428 	key_put(params.key);
429 	_leave(" = %d", ret);
430 	return ret;
431 }
432 
433 /*
434  * finish the unmounting process on the superblock
435  */
436 static void afs_put_super(struct super_block *sb)
437 {
438 	struct afs_super_info *as = sb->s_fs_info;
439 
440 	_enter("");
441 
442 	afs_put_volume(as->volume);
443 
444 	_leave("");
445 }
446 
447 /*
448  * initialise an inode cache slab element prior to any use
449  */
450 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
451 			    unsigned long flags)
452 {
453 	struct afs_vnode *vnode = _vnode;
454 
455 	if (flags & SLAB_CTOR_CONSTRUCTOR) {
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_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
465 	}
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