xref: /openbmc/linux/fs/afs/super.c (revision 887069f4) 
1 /* AFS superblock handling
2  *
3  * Copyright (c) 2002, 2007, 2018 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/fs_parser.h>
25 #include <linux/statfs.h>
26 #include <linux/sched.h>
27 #include <linux/nsproxy.h>
28 #include <linux/magic.h>
29 #include <net/net_namespace.h>
30 #include "internal.h"
31 
32 static void afs_i_init_once(void *foo);
33 static void afs_kill_super(struct super_block *sb);
34 static struct inode *afs_alloc_inode(struct super_block *sb);
35 static void afs_destroy_inode(struct inode *inode);
36 static void afs_free_inode(struct inode *inode);
37 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
38 static int afs_show_devname(struct seq_file *m, struct dentry *root);
39 static int afs_show_options(struct seq_file *m, struct dentry *root);
40 static int afs_init_fs_context(struct fs_context *fc);
41 static const struct fs_parameter_spec afs_fs_parameters[];
42 
43 struct file_system_type afs_fs_type = {
44 	.owner			= THIS_MODULE,
45 	.name			= "afs",
46 	.init_fs_context	= afs_init_fs_context,
47 	.parameters		= afs_fs_parameters,
48 	.kill_sb		= afs_kill_super,
49 	.fs_flags		= FS_RENAME_DOES_D_MOVE,
50 };
51 MODULE_ALIAS_FS("afs");
52 
53 int afs_net_id;
54 
55 static const struct super_operations afs_super_ops = {
56 	.statfs		= afs_statfs,
57 	.alloc_inode	= afs_alloc_inode,
58 	.drop_inode	= afs_drop_inode,
59 	.destroy_inode	= afs_destroy_inode,
60 	.free_inode	= afs_free_inode,
61 	.evict_inode	= afs_evict_inode,
62 	.show_devname	= afs_show_devname,
63 	.show_options	= afs_show_options,
64 };
65 
66 static struct kmem_cache *afs_inode_cachep;
67 static atomic_t afs_count_active_inodes;
68 
69 enum afs_param {
70 	Opt_autocell,
71 	Opt_dyn,
72 	Opt_flock,
73 	Opt_source,
74 };
75 
76 static const struct constant_table afs_param_flock[] = {
77 	{"local",	afs_flock_mode_local },
78 	{"openafs",	afs_flock_mode_openafs },
79 	{"strict",	afs_flock_mode_strict },
80 	{"write",	afs_flock_mode_write },
81 	{}
82 };
83 
84 static const struct fs_parameter_spec afs_fs_parameters[] = {
85 	fsparam_flag  ("autocell",	Opt_autocell),
86 	fsparam_flag  ("dyn",		Opt_dyn),
87 	fsparam_enum  ("flock",		Opt_flock, afs_param_flock),
88 	fsparam_string("source",	Opt_source),
89 	{}
90 };
91 
92 /*
93  * initialise the filesystem
94  */
95 int __init afs_fs_init(void)
96 {
97 	int ret;
98 
99 	_enter("");
100 
101 	/* create ourselves an inode cache */
102 	atomic_set(&afs_count_active_inodes, 0);
103 
104 	ret = -ENOMEM;
105 	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
106 					     sizeof(struct afs_vnode),
107 					     0,
108 					     SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
109 					     afs_i_init_once);
110 	if (!afs_inode_cachep) {
111 		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
112 		return ret;
113 	}
114 
115 	/* now export our filesystem to lesser mortals */
116 	ret = register_filesystem(&afs_fs_type);
117 	if (ret < 0) {
118 		kmem_cache_destroy(afs_inode_cachep);
119 		_leave(" = %d", ret);
120 		return ret;
121 	}
122 
123 	_leave(" = 0");
124 	return 0;
125 }
126 
127 /*
128  * clean up the filesystem
129  */
130 void afs_fs_exit(void)
131 {
132 	_enter("");
133 
134 	afs_mntpt_kill_timer();
135 	unregister_filesystem(&afs_fs_type);
136 
137 	if (atomic_read(&afs_count_active_inodes) != 0) {
138 		printk("kAFS: %d active inode objects still present\n",
139 		       atomic_read(&afs_count_active_inodes));
140 		BUG();
141 	}
142 
143 	/*
144 	 * Make sure all delayed rcu free inodes are flushed before we
145 	 * destroy cache.
146 	 */
147 	rcu_barrier();
148 	kmem_cache_destroy(afs_inode_cachep);
149 	_leave("");
150 }
151 
152 /*
153  * Display the mount device name in /proc/mounts.
154  */
155 static int afs_show_devname(struct seq_file *m, struct dentry *root)
156 {
157 	struct afs_super_info *as = AFS_FS_S(root->d_sb);
158 	struct afs_volume *volume = as->volume;
159 	struct afs_cell *cell = as->cell;
160 	const char *suf = "";
161 	char pref = '%';
162 
163 	if (as->dyn_root) {
164 		seq_puts(m, "none");
165 		return 0;
166 	}
167 
168 	switch (volume->type) {
169 	case AFSVL_RWVOL:
170 		break;
171 	case AFSVL_ROVOL:
172 		pref = '#';
173 		if (volume->type_force)
174 			suf = ".readonly";
175 		break;
176 	case AFSVL_BACKVOL:
177 		pref = '#';
178 		suf = ".backup";
179 		break;
180 	}
181 
182 	seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
183 	return 0;
184 }
185 
186 /*
187  * Display the mount options in /proc/mounts.
188  */
189 static int afs_show_options(struct seq_file *m, struct dentry *root)
190 {
191 	struct afs_super_info *as = AFS_FS_S(root->d_sb);
192 	const char *p = NULL;
193 
194 	if (as->dyn_root)
195 		seq_puts(m, ",dyn");
196 	if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
197 		seq_puts(m, ",autocell");
198 	switch (as->flock_mode) {
199 	case afs_flock_mode_unset:	break;
200 	case afs_flock_mode_local:	p = "local";	break;
201 	case afs_flock_mode_openafs:	p = "openafs";	break;
202 	case afs_flock_mode_strict:	p = "strict";	break;
203 	case afs_flock_mode_write:	p = "write";	break;
204 	}
205 	if (p)
206 		seq_printf(m, ",flock=%s", p);
207 
208 	return 0;
209 }
210 
211 /*
212  * Parse the source name to get cell name, volume name, volume type and R/W
213  * selector.
214  *
215  * This can be one of the following:
216  *	"%[cell:]volume[.]"		R/W volume
217  *	"#[cell:]volume[.]"		R/O or R/W volume (R/O parent),
218  *					 or R/W (R/W parent) volume
219  *	"%[cell:]volume.readonly"	R/O volume
220  *	"#[cell:]volume.readonly"	R/O volume
221  *	"%[cell:]volume.backup"		Backup volume
222  *	"#[cell:]volume.backup"		Backup volume
223  */
224 static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
225 {
226 	struct afs_fs_context *ctx = fc->fs_private;
227 	struct afs_cell *cell;
228 	const char *cellname, *suffix, *name = param->string;
229 	int cellnamesz;
230 
231 	_enter(",%s", name);
232 
233 	if (fc->source)
234 		return invalf(fc, "kAFS: Multiple sources not supported");
235 
236 	if (!name) {
237 		printk(KERN_ERR "kAFS: no volume name specified\n");
238 		return -EINVAL;
239 	}
240 
241 	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
242 		/* To use dynroot, we don't want to have to provide a source */
243 		if (strcmp(name, "none") == 0) {
244 			ctx->no_cell = true;
245 			return 0;
246 		}
247 		printk(KERN_ERR "kAFS: unparsable volume name\n");
248 		return -EINVAL;
249 	}
250 
251 	/* determine the type of volume we're looking for */
252 	if (name[0] == '%') {
253 		ctx->type = AFSVL_RWVOL;
254 		ctx->force = true;
255 	}
256 	name++;
257 
258 	/* split the cell name out if there is one */
259 	ctx->volname = strchr(name, ':');
260 	if (ctx->volname) {
261 		cellname = name;
262 		cellnamesz = ctx->volname - name;
263 		ctx->volname++;
264 	} else {
265 		ctx->volname = name;
266 		cellname = NULL;
267 		cellnamesz = 0;
268 	}
269 
270 	/* the volume type is further affected by a possible suffix */
271 	suffix = strrchr(ctx->volname, '.');
272 	if (suffix) {
273 		if (strcmp(suffix, ".readonly") == 0) {
274 			ctx->type = AFSVL_ROVOL;
275 			ctx->force = true;
276 		} else if (strcmp(suffix, ".backup") == 0) {
277 			ctx->type = AFSVL_BACKVOL;
278 			ctx->force = true;
279 		} else if (suffix[1] == 0) {
280 		} else {
281 			suffix = NULL;
282 		}
283 	}
284 
285 	ctx->volnamesz = suffix ?
286 		suffix - ctx->volname : strlen(ctx->volname);
287 
288 	_debug("cell %*.*s [%p]",
289 	       cellnamesz, cellnamesz, cellname ?: "", ctx->cell);
290 
291 	/* lookup the cell record */
292 	if (cellname) {
293 		cell = afs_lookup_cell(ctx->net, cellname, cellnamesz,
294 				       NULL, false);
295 		if (IS_ERR(cell)) {
296 			pr_err("kAFS: unable to lookup cell '%*.*s'\n",
297 			       cellnamesz, cellnamesz, cellname ?: "");
298 			return PTR_ERR(cell);
299 		}
300 		afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_parse);
301 		afs_see_cell(cell, afs_cell_trace_see_source);
302 		ctx->cell = cell;
303 	}
304 
305 	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
306 	       ctx->cell->name, ctx->cell,
307 	       ctx->volnamesz, ctx->volnamesz, ctx->volname,
308 	       suffix ?: "-", ctx->type, ctx->force ? " FORCE" : "");
309 
310 	fc->source = param->string;
311 	param->string = NULL;
312 	return 0;
313 }
314 
315 /*
316  * Parse a single mount parameter.
317  */
318 static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
319 {
320 	struct fs_parse_result result;
321 	struct afs_fs_context *ctx = fc->fs_private;
322 	int opt;
323 
324 	opt = fs_parse(fc, afs_fs_parameters, param, &result);
325 	if (opt < 0)
326 		return opt;
327 
328 	switch (opt) {
329 	case Opt_source:
330 		return afs_parse_source(fc, param);
331 
332 	case Opt_autocell:
333 		ctx->autocell = true;
334 		break;
335 
336 	case Opt_dyn:
337 		ctx->dyn_root = true;
338 		break;
339 
340 	case Opt_flock:
341 		ctx->flock_mode = result.uint_32;
342 		break;
343 
344 	default:
345 		return -EINVAL;
346 	}
347 
348 	_leave(" = 0");
349 	return 0;
350 }
351 
352 /*
353  * Validate the options, get the cell key and look up the volume.
354  */
355 static int afs_validate_fc(struct fs_context *fc)
356 {
357 	struct afs_fs_context *ctx = fc->fs_private;
358 	struct afs_volume *volume;
359 	struct afs_cell *cell;
360 	struct key *key;
361 	int ret;
362 
363 	if (!ctx->dyn_root) {
364 		if (ctx->no_cell) {
365 			pr_warn("kAFS: Can only specify source 'none' with -o dyn\n");
366 			return -EINVAL;
367 		}
368 
369 		if (!ctx->cell) {
370 			pr_warn("kAFS: No cell specified\n");
371 			return -EDESTADDRREQ;
372 		}
373 
374 	reget_key:
375 		/* We try to do the mount securely. */
376 		key = afs_request_key(ctx->cell);
377 		if (IS_ERR(key))
378 			return PTR_ERR(key);
379 
380 		ctx->key = key;
381 
382 		if (ctx->volume) {
383 			afs_put_volume(ctx->net, ctx->volume,
384 				       afs_volume_trace_put_validate_fc);
385 			ctx->volume = NULL;
386 		}
387 
388 		if (test_bit(AFS_CELL_FL_CHECK_ALIAS, &ctx->cell->flags)) {
389 			ret = afs_cell_detect_alias(ctx->cell, key);
390 			if (ret < 0)
391 				return ret;
392 			if (ret == 1) {
393 				_debug("switch to alias");
394 				key_put(ctx->key);
395 				ctx->key = NULL;
396 				cell = afs_use_cell(ctx->cell->alias_of,
397 						    afs_cell_trace_use_fc_alias);
398 				afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
399 				ctx->cell = cell;
400 				goto reget_key;
401 			}
402 		}
403 
404 		volume = afs_create_volume(ctx);
405 		if (IS_ERR(volume))
406 			return PTR_ERR(volume);
407 
408 		ctx->volume = volume;
409 	}
410 
411 	return 0;
412 }
413 
414 /*
415  * check a superblock to see if it's the one we're looking for
416  */
417 static int afs_test_super(struct super_block *sb, struct fs_context *fc)
418 {
419 	struct afs_fs_context *ctx = fc->fs_private;
420 	struct afs_super_info *as = AFS_FS_S(sb);
421 
422 	return (as->net_ns == fc->net_ns &&
423 		as->volume &&
424 		as->volume->vid == ctx->volume->vid &&
425 		as->cell == ctx->cell &&
426 		!as->dyn_root);
427 }
428 
429 static int afs_dynroot_test_super(struct super_block *sb, struct fs_context *fc)
430 {
431 	struct afs_super_info *as = AFS_FS_S(sb);
432 
433 	return (as->net_ns == fc->net_ns &&
434 		as->dyn_root);
435 }
436 
437 static int afs_set_super(struct super_block *sb, struct fs_context *fc)
438 {
439 	return set_anon_super(sb, NULL);
440 }
441 
442 /*
443  * fill in the superblock
444  */
445 static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
446 {
447 	struct afs_super_info *as = AFS_FS_S(sb);
448 	struct inode *inode = NULL;
449 	int ret;
450 
451 	_enter("");
452 
453 	/* fill in the superblock */
454 	sb->s_blocksize		= PAGE_SIZE;
455 	sb->s_blocksize_bits	= PAGE_SHIFT;
456 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
457 	sb->s_magic		= AFS_FS_MAGIC;
458 	sb->s_op		= &afs_super_ops;
459 	if (!as->dyn_root)
460 		sb->s_xattr	= afs_xattr_handlers;
461 	ret = super_setup_bdi(sb);
462 	if (ret)
463 		return ret;
464 
465 	/* allocate the root inode and dentry */
466 	if (as->dyn_root) {
467 		inode = afs_iget_pseudo_dir(sb, true);
468 	} else {
469 		sprintf(sb->s_id, "%llu", as->volume->vid);
470 		afs_activate_volume(as->volume);
471 		inode = afs_root_iget(sb, ctx->key);
472 	}
473 
474 	if (IS_ERR(inode))
475 		return PTR_ERR(inode);
476 
477 	if (ctx->autocell || as->dyn_root)
478 		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
479 
480 	ret = -ENOMEM;
481 	sb->s_root = d_make_root(inode);
482 	if (!sb->s_root)
483 		goto error;
484 
485 	if (as->dyn_root) {
486 		sb->s_d_op = &afs_dynroot_dentry_operations;
487 		ret = afs_dynroot_populate(sb);
488 		if (ret < 0)
489 			goto error;
490 	} else {
491 		sb->s_d_op = &afs_fs_dentry_operations;
492 		rcu_assign_pointer(as->volume->sb, sb);
493 	}
494 
495 	_leave(" = 0");
496 	return 0;
497 
498 error:
499 	_leave(" = %d", ret);
500 	return ret;
501 }
502 
503 static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
504 {
505 	struct afs_fs_context *ctx = fc->fs_private;
506 	struct afs_super_info *as;
507 
508 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
509 	if (as) {
510 		as->net_ns = get_net(fc->net_ns);
511 		as->flock_mode = ctx->flock_mode;
512 		if (ctx->dyn_root) {
513 			as->dyn_root = true;
514 		} else {
515 			as->cell = afs_use_cell(ctx->cell, afs_cell_trace_use_sbi);
516 			as->volume = afs_get_volume(ctx->volume,
517 						    afs_volume_trace_get_alloc_sbi);
518 		}
519 	}
520 	return as;
521 }
522 
523 static void afs_destroy_sbi(struct afs_super_info *as)
524 {
525 	if (as) {
526 		struct afs_net *net = afs_net(as->net_ns);
527 		afs_put_volume(net, as->volume, afs_volume_trace_put_destroy_sbi);
528 		afs_unuse_cell(net, as->cell, afs_cell_trace_unuse_sbi);
529 		put_net(as->net_ns);
530 		kfree(as);
531 	}
532 }
533 
534 static void afs_kill_super(struct super_block *sb)
535 {
536 	struct afs_super_info *as = AFS_FS_S(sb);
537 
538 	if (as->dyn_root)
539 		afs_dynroot_depopulate(sb);
540 
541 	/* Clear the callback interests (which will do ilookup5) before
542 	 * deactivating the superblock.
543 	 */
544 	if (as->volume)
545 		rcu_assign_pointer(as->volume->sb, NULL);
546 	kill_anon_super(sb);
547 	if (as->volume)
548 		afs_deactivate_volume(as->volume);
549 	afs_destroy_sbi(as);
550 }
551 
552 /*
553  * Get an AFS superblock and root directory.
554  */
555 static int afs_get_tree(struct fs_context *fc)
556 {
557 	struct afs_fs_context *ctx = fc->fs_private;
558 	struct super_block *sb;
559 	struct afs_super_info *as;
560 	int ret;
561 
562 	ret = afs_validate_fc(fc);
563 	if (ret)
564 		goto error;
565 
566 	_enter("");
567 
568 	/* allocate a superblock info record */
569 	ret = -ENOMEM;
570 	as = afs_alloc_sbi(fc);
571 	if (!as)
572 		goto error;
573 	fc->s_fs_info = as;
574 
575 	/* allocate a deviceless superblock */
576 	sb = sget_fc(fc,
577 		     as->dyn_root ? afs_dynroot_test_super : afs_test_super,
578 		     afs_set_super);
579 	if (IS_ERR(sb)) {
580 		ret = PTR_ERR(sb);
581 		goto error;
582 	}
583 
584 	if (!sb->s_root) {
585 		/* initial superblock/root creation */
586 		_debug("create");
587 		ret = afs_fill_super(sb, ctx);
588 		if (ret < 0)
589 			goto error_sb;
590 		sb->s_flags |= SB_ACTIVE;
591 	} else {
592 		_debug("reuse");
593 		ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
594 	}
595 
596 	fc->root = dget(sb->s_root);
597 	trace_afs_get_tree(as->cell, as->volume);
598 	_leave(" = 0 [%p]", sb);
599 	return 0;
600 
601 error_sb:
602 	deactivate_locked_super(sb);
603 error:
604 	_leave(" = %d", ret);
605 	return ret;
606 }
607 
608 static void afs_free_fc(struct fs_context *fc)
609 {
610 	struct afs_fs_context *ctx = fc->fs_private;
611 
612 	afs_destroy_sbi(fc->s_fs_info);
613 	afs_put_volume(ctx->net, ctx->volume, afs_volume_trace_put_free_fc);
614 	afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
615 	key_put(ctx->key);
616 	kfree(ctx);
617 }
618 
619 static const struct fs_context_operations afs_context_ops = {
620 	.free		= afs_free_fc,
621 	.parse_param	= afs_parse_param,
622 	.get_tree	= afs_get_tree,
623 };
624 
625 /*
626  * Set up the filesystem mount context.
627  */
628 static int afs_init_fs_context(struct fs_context *fc)
629 {
630 	struct afs_fs_context *ctx;
631 	struct afs_cell *cell;
632 
633 	ctx = kzalloc(sizeof(struct afs_fs_context), GFP_KERNEL);
634 	if (!ctx)
635 		return -ENOMEM;
636 
637 	ctx->type = AFSVL_ROVOL;
638 	ctx->net = afs_net(fc->net_ns);
639 
640 	/* Default to the workstation cell. */
641 	cell = afs_find_cell(ctx->net, NULL, 0, afs_cell_trace_use_fc);
642 	if (IS_ERR(cell))
643 		cell = NULL;
644 	ctx->cell = cell;
645 
646 	fc->fs_private = ctx;
647 	fc->ops = &afs_context_ops;
648 	return 0;
649 }
650 
651 /*
652  * Initialise an inode cache slab element prior to any use.  Note that
653  * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
654  * inode to another.
655  */
656 static void afs_i_init_once(void *_vnode)
657 {
658 	struct afs_vnode *vnode = _vnode;
659 
660 	memset(vnode, 0, sizeof(*vnode));
661 	inode_init_once(&vnode->vfs_inode);
662 	mutex_init(&vnode->io_lock);
663 	init_rwsem(&vnode->validate_lock);
664 	spin_lock_init(&vnode->wb_lock);
665 	spin_lock_init(&vnode->lock);
666 	INIT_LIST_HEAD(&vnode->wb_keys);
667 	INIT_LIST_HEAD(&vnode->pending_locks);
668 	INIT_LIST_HEAD(&vnode->granted_locks);
669 	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
670 	seqlock_init(&vnode->cb_lock);
671 }
672 
673 /*
674  * allocate an AFS inode struct from our slab cache
675  */
676 static struct inode *afs_alloc_inode(struct super_block *sb)
677 {
678 	struct afs_vnode *vnode;
679 
680 	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
681 	if (!vnode)
682 		return NULL;
683 
684 	atomic_inc(&afs_count_active_inodes);
685 
686 	/* Reset anything that shouldn't leak from one inode to the next. */
687 	memset(&vnode->fid, 0, sizeof(vnode->fid));
688 	memset(&vnode->status, 0, sizeof(vnode->status));
689 
690 	vnode->volume		= NULL;
691 	vnode->lock_key		= NULL;
692 	vnode->permit_cache	= NULL;
693 #ifdef CONFIG_AFS_FSCACHE
694 	vnode->cache		= NULL;
695 #endif
696 
697 	vnode->flags		= 1 << AFS_VNODE_UNSET;
698 	vnode->lock_state	= AFS_VNODE_LOCK_NONE;
699 
700 	init_rwsem(&vnode->rmdir_lock);
701 	INIT_WORK(&vnode->cb_work, afs_invalidate_mmap_work);
702 
703 	_leave(" = %p", &vnode->vfs_inode);
704 	return &vnode->vfs_inode;
705 }
706 
707 static void afs_free_inode(struct inode *inode)
708 {
709 	kmem_cache_free(afs_inode_cachep, AFS_FS_I(inode));
710 }
711 
712 /*
713  * destroy an AFS inode struct
714  */
715 static void afs_destroy_inode(struct inode *inode)
716 {
717 	struct afs_vnode *vnode = AFS_FS_I(inode);
718 
719 	_enter("%p{%llx:%llu}", inode, vnode->fid.vid, vnode->fid.vnode);
720 
721 	_debug("DESTROY INODE %p", inode);
722 
723 	atomic_dec(&afs_count_active_inodes);
724 }
725 
726 static void afs_get_volume_status_success(struct afs_operation *op)
727 {
728 	struct afs_volume_status *vs = &op->volstatus.vs;
729 	struct kstatfs *buf = op->volstatus.buf;
730 
731 	if (vs->max_quota == 0)
732 		buf->f_blocks = vs->part_max_blocks;
733 	else
734 		buf->f_blocks = vs->max_quota;
735 
736 	if (buf->f_blocks > vs->blocks_in_use)
737 		buf->f_bavail = buf->f_bfree =
738 			buf->f_blocks - vs->blocks_in_use;
739 }
740 
741 static const struct afs_operation_ops afs_get_volume_status_operation = {
742 	.issue_afs_rpc	= afs_fs_get_volume_status,
743 	.issue_yfs_rpc	= yfs_fs_get_volume_status,
744 	.success	= afs_get_volume_status_success,
745 };
746 
747 /*
748  * return information about an AFS volume
749  */
750 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
751 {
752 	struct afs_super_info *as = AFS_FS_S(dentry->d_sb);
753 	struct afs_operation *op;
754 	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
755 
756 	buf->f_type	= dentry->d_sb->s_magic;
757 	buf->f_bsize	= AFS_BLOCK_SIZE;
758 	buf->f_namelen	= AFSNAMEMAX - 1;
759 
760 	if (as->dyn_root) {
761 		buf->f_blocks	= 1;
762 		buf->f_bavail	= 0;
763 		buf->f_bfree	= 0;
764 		return 0;
765 	}
766 
767 	op = afs_alloc_operation(NULL, as->volume);
768 	if (IS_ERR(op))
769 		return PTR_ERR(op);
770 
771 	afs_op_set_vnode(op, 0, vnode);
772 	op->nr_files		= 1;
773 	op->volstatus.buf	= buf;
774 	op->ops			= &afs_get_volume_status_operation;
775 	return afs_do_sync_operation(op);
776 }
777