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
30static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
31			    unsigned long flags);
32static int afs_get_sb(struct file_system_type *fs_type,
33		      int flags, const char *dev_name,
34		      void *data, struct vfsmount *mnt);
35static struct inode *afs_alloc_inode(struct super_block *sb);
36static void afs_put_super(struct super_block *sb);
37static void afs_destroy_inode(struct inode *inode);
38static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
39
40struct 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
48static 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
58static struct kmem_cache *afs_inode_cachep;
59static atomic_t afs_count_active_inodes;
60
61enum {
62	afs_no_opt,
63	afs_opt_cell,
64	afs_opt_rwpath,
65	afs_opt_vol,
66};
67
68static 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 */
78int __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 */
114void __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 */
136static 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 */
194static 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 */
278static 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 */
289static 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
335error_inode:
336	ret = PTR_ERR(inode);
337	inode = NULL;
338error:
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 */
352static 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
425error:
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 */
436static 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 */
450static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
451			    unsigned long flags)
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_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
464}
465
466/*
467 * allocate an AFS inode struct from our slab cache
468 */
469static struct inode *afs_alloc_inode(struct super_block *sb)
470{
471	struct afs_vnode *vnode;
472
473	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
474	if (!vnode)
475		return NULL;
476
477	atomic_inc(&afs_count_active_inodes);
478
479	memset(&vnode->fid, 0, sizeof(vnode->fid));
480	memset(&vnode->status, 0, sizeof(vnode->status));
481
482	vnode->volume		= NULL;
483	vnode->update_cnt	= 0;
484	vnode->flags		= 1 << AFS_VNODE_UNSET;
485	vnode->cb_promised	= false;
486
487	_leave(" = %p", &vnode->vfs_inode);
488	return &vnode->vfs_inode;
489}
490
491/*
492 * destroy an AFS inode struct
493 */
494static void afs_destroy_inode(struct inode *inode)
495{
496	struct afs_vnode *vnode = AFS_FS_I(inode);
497
498	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
499
500	_debug("DESTROY INODE %p", inode);
501
502	ASSERTCMP(vnode->server, ==, NULL);
503
504	kmem_cache_free(afs_inode_cachep, vnode);
505	atomic_dec(&afs_count_active_inodes);
506}
507
508/*
509 * return information about an AFS volume
510 */
511static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
512{
513	struct afs_volume_status vs;
514	struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
515	struct key *key;
516	int ret;
517
518	key = afs_request_key(vnode->volume->cell);
519	if (IS_ERR(key))
520		return PTR_ERR(key);
521
522	ret = afs_vnode_get_volume_status(vnode, key, &vs);
523	key_put(key);
524	if (ret < 0) {
525		_leave(" = %d", ret);
526		return ret;
527	}
528
529	buf->f_type	= dentry->d_sb->s_magic;
530	buf->f_bsize	= AFS_BLOCK_SIZE;
531	buf->f_namelen	= AFSNAMEMAX - 1;
532
533	if (vs.max_quota == 0)
534		buf->f_blocks = vs.part_max_blocks;
535	else
536		buf->f_blocks = vs.max_quota;
537	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
538	return 0;
539}
540