xref: /kernel/linux/linux-6.6/fs/afs/super.c (revision 62306a36) 
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
32static void afs_i_init_once(void *foo);
33static void afs_kill_super(struct super_block *sb);
34static struct inode *afs_alloc_inode(struct super_block *sb);
35static void afs_destroy_inode(struct inode *inode);
36static void afs_free_inode(struct inode *inode);
37static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
38static int afs_show_devname(struct seq_file *m, struct dentry *root);
39static int afs_show_options(struct seq_file *m, struct dentry *root);
40static int afs_init_fs_context(struct fs_context *fc);
41static const struct fs_parameter_spec afs_fs_parameters[];
42
43struct 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};
51MODULE_ALIAS_FS("afs");
52
53int afs_net_id;
54
55static const struct super_operations afs_super_ops = {
56	.statfs		= afs_statfs,
57	.alloc_inode	= afs_alloc_inode,
58	.write_inode	= afs_write_inode,
59	.drop_inode	= afs_drop_inode,
60	.destroy_inode	= afs_destroy_inode,
61	.free_inode	= afs_free_inode,
62	.evict_inode	= afs_evict_inode,
63	.show_devname	= afs_show_devname,
64	.show_options	= afs_show_options,
65};
66
67static struct kmem_cache *afs_inode_cachep;
68static atomic_t afs_count_active_inodes;
69
70enum afs_param {
71	Opt_autocell,
72	Opt_dyn,
73	Opt_flock,
74	Opt_source,
75};
76
77static const struct constant_table afs_param_flock[] = {
78	{"local",	afs_flock_mode_local },
79	{"openafs",	afs_flock_mode_openafs },
80	{"strict",	afs_flock_mode_strict },
81	{"write",	afs_flock_mode_write },
82	{}
83};
84
85static const struct fs_parameter_spec afs_fs_parameters[] = {
86	fsparam_flag  ("autocell",	Opt_autocell),
87	fsparam_flag  ("dyn",		Opt_dyn),
88	fsparam_enum  ("flock",		Opt_flock, afs_param_flock),
89	fsparam_string("source",	Opt_source),
90	{}
91};
92
93/*
94 * initialise the filesystem
95 */
96int __init afs_fs_init(void)
97{
98	int ret;
99
100	_enter("");
101
102	/* create ourselves an inode cache */
103	atomic_set(&afs_count_active_inodes, 0);
104
105	ret = -ENOMEM;
106	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
107					     sizeof(struct afs_vnode),
108					     0,
109					     SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
110					     afs_i_init_once);
111	if (!afs_inode_cachep) {
112		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
113		return ret;
114	}
115
116	/* now export our filesystem to lesser mortals */
117	ret = register_filesystem(&afs_fs_type);
118	if (ret < 0) {
119		kmem_cache_destroy(afs_inode_cachep);
120		_leave(" = %d", ret);
121		return ret;
122	}
123
124	_leave(" = 0");
125	return 0;
126}
127
128/*
129 * clean up the filesystem
130 */
131void afs_fs_exit(void)
132{
133	_enter("");
134
135	afs_mntpt_kill_timer();
136	unregister_filesystem(&afs_fs_type);
137
138	if (atomic_read(&afs_count_active_inodes) != 0) {
139		printk("kAFS: %d active inode objects still present\n",
140		       atomic_read(&afs_count_active_inodes));
141		BUG();
142	}
143
144	/*
145	 * Make sure all delayed rcu free inodes are flushed before we
146	 * destroy cache.
147	 */
148	rcu_barrier();
149	kmem_cache_destroy(afs_inode_cachep);
150	_leave("");
151}
152
153/*
154 * Display the mount device name in /proc/mounts.
155 */
156static int afs_show_devname(struct seq_file *m, struct dentry *root)
157{
158	struct afs_super_info *as = AFS_FS_S(root->d_sb);
159	struct afs_volume *volume = as->volume;
160	struct afs_cell *cell = as->cell;
161	const char *suf = "";
162	char pref = '%';
163
164	if (as->dyn_root) {
165		seq_puts(m, "none");
166		return 0;
167	}
168
169	switch (volume->type) {
170	case AFSVL_RWVOL:
171		break;
172	case AFSVL_ROVOL:
173		pref = '#';
174		if (volume->type_force)
175			suf = ".readonly";
176		break;
177	case AFSVL_BACKVOL:
178		pref = '#';
179		suf = ".backup";
180		break;
181	}
182
183	seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
184	return 0;
185}
186
187/*
188 * Display the mount options in /proc/mounts.
189 */
190static int afs_show_options(struct seq_file *m, struct dentry *root)
191{
192	struct afs_super_info *as = AFS_FS_S(root->d_sb);
193	const char *p = NULL;
194
195	if (as->dyn_root)
196		seq_puts(m, ",dyn");
197	if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
198		seq_puts(m, ",autocell");
199	switch (as->flock_mode) {
200	case afs_flock_mode_unset:	break;
201	case afs_flock_mode_local:	p = "local";	break;
202	case afs_flock_mode_openafs:	p = "openafs";	break;
203	case afs_flock_mode_strict:	p = "strict";	break;
204	case afs_flock_mode_write:	p = "write";	break;
205	}
206	if (p)
207		seq_printf(m, ",flock=%s", p);
208
209	return 0;
210}
211
212/*
213 * Parse the source name to get cell name, volume name, volume type and R/W
214 * selector.
215 *
216 * This can be one of the following:
217 *	"%[cell:]volume[.]"		R/W volume
218 *	"#[cell:]volume[.]"		R/O or R/W volume (R/O parent),
219 *					 or R/W (R/W parent) volume
220 *	"%[cell:]volume.readonly"	R/O volume
221 *	"#[cell:]volume.readonly"	R/O volume
222 *	"%[cell:]volume.backup"		Backup volume
223 *	"#[cell:]volume.backup"		Backup volume
224 */
225static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
226{
227	struct afs_fs_context *ctx = fc->fs_private;
228	struct afs_cell *cell;
229	const char *cellname, *suffix, *name = param->string;
230	int cellnamesz;
231
232	_enter(",%s", name);
233
234	if (fc->source)
235		return invalf(fc, "kAFS: Multiple sources not supported");
236
237	if (!name) {
238		printk(KERN_ERR "kAFS: no volume name specified\n");
239		return -EINVAL;
240	}
241
242	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
243		/* To use dynroot, we don't want to have to provide a source */
244		if (strcmp(name, "none") == 0) {
245			ctx->no_cell = true;
246			return 0;
247		}
248		printk(KERN_ERR "kAFS: unparsable volume name\n");
249		return -EINVAL;
250	}
251
252	/* determine the type of volume we're looking for */
253	if (name[0] == '%') {
254		ctx->type = AFSVL_RWVOL;
255		ctx->force = true;
256	}
257	name++;
258
259	/* split the cell name out if there is one */
260	ctx->volname = strchr(name, ':');
261	if (ctx->volname) {
262		cellname = name;
263		cellnamesz = ctx->volname - name;
264		ctx->volname++;
265	} else {
266		ctx->volname = name;
267		cellname = NULL;
268		cellnamesz = 0;
269	}
270
271	/* the volume type is further affected by a possible suffix */
272	suffix = strrchr(ctx->volname, '.');
273	if (suffix) {
274		if (strcmp(suffix, ".readonly") == 0) {
275			ctx->type = AFSVL_ROVOL;
276			ctx->force = true;
277		} else if (strcmp(suffix, ".backup") == 0) {
278			ctx->type = AFSVL_BACKVOL;
279			ctx->force = true;
280		} else if (suffix[1] == 0) {
281		} else {
282			suffix = NULL;
283		}
284	}
285
286	ctx->volnamesz = suffix ?
287		suffix - ctx->volname : strlen(ctx->volname);
288
289	_debug("cell %*.*s [%p]",
290	       cellnamesz, cellnamesz, cellname ?: "", ctx->cell);
291
292	/* lookup the cell record */
293	if (cellname) {
294		cell = afs_lookup_cell(ctx->net, cellname, cellnamesz,
295				       NULL, false);
296		if (IS_ERR(cell)) {
297			pr_err("kAFS: unable to lookup cell '%*.*s'\n",
298			       cellnamesz, cellnamesz, cellname ?: "");
299			return PTR_ERR(cell);
300		}
301		afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_parse);
302		afs_see_cell(cell, afs_cell_trace_see_source);
303		ctx->cell = cell;
304	}
305
306	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
307	       ctx->cell->name, ctx->cell,
308	       ctx->volnamesz, ctx->volnamesz, ctx->volname,
309	       suffix ?: "-", ctx->type, ctx->force ? " FORCE" : "");
310
311	fc->source = param->string;
312	param->string = NULL;
313	return 0;
314}
315
316/*
317 * Parse a single mount parameter.
318 */
319static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
320{
321	struct fs_parse_result result;
322	struct afs_fs_context *ctx = fc->fs_private;
323	int opt;
324
325	opt = fs_parse(fc, afs_fs_parameters, param, &result);
326	if (opt < 0)
327		return opt;
328
329	switch (opt) {
330	case Opt_source:
331		return afs_parse_source(fc, param);
332
333	case Opt_autocell:
334		ctx->autocell = true;
335		break;
336
337	case Opt_dyn:
338		ctx->dyn_root = true;
339		break;
340
341	case Opt_flock:
342		ctx->flock_mode = result.uint_32;
343		break;
344
345	default:
346		return -EINVAL;
347	}
348
349	_leave(" = 0");
350	return 0;
351}
352
353/*
354 * Validate the options, get the cell key and look up the volume.
355 */
356static int afs_validate_fc(struct fs_context *fc)
357{
358	struct afs_fs_context *ctx = fc->fs_private;
359	struct afs_volume *volume;
360	struct afs_cell *cell;
361	struct key *key;
362	int ret;
363
364	if (!ctx->dyn_root) {
365		if (ctx->no_cell) {
366			pr_warn("kAFS: Can only specify source 'none' with -o dyn\n");
367			return -EINVAL;
368		}
369
370		if (!ctx->cell) {
371			pr_warn("kAFS: No cell specified\n");
372			return -EDESTADDRREQ;
373		}
374
375	reget_key:
376		/* We try to do the mount securely. */
377		key = afs_request_key(ctx->cell);
378		if (IS_ERR(key))
379			return PTR_ERR(key);
380
381		ctx->key = key;
382
383		if (ctx->volume) {
384			afs_put_volume(ctx->net, ctx->volume,
385				       afs_volume_trace_put_validate_fc);
386			ctx->volume = NULL;
387		}
388
389		if (test_bit(AFS_CELL_FL_CHECK_ALIAS, &ctx->cell->flags)) {
390			ret = afs_cell_detect_alias(ctx->cell, key);
391			if (ret < 0)
392				return ret;
393			if (ret == 1) {
394				_debug("switch to alias");
395				key_put(ctx->key);
396				ctx->key = NULL;
397				cell = afs_use_cell(ctx->cell->alias_of,
398						    afs_cell_trace_use_fc_alias);
399				afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
400				ctx->cell = cell;
401				goto reget_key;
402			}
403		}
404
405		volume = afs_create_volume(ctx);
406		if (IS_ERR(volume))
407			return PTR_ERR(volume);
408
409		ctx->volume = volume;
410		if (volume->type != AFSVL_RWVOL)
411			ctx->flock_mode = afs_flock_mode_local;
412	}
413
414	return 0;
415}
416
417/*
418 * check a superblock to see if it's the one we're looking for
419 */
420static int afs_test_super(struct super_block *sb, struct fs_context *fc)
421{
422	struct afs_fs_context *ctx = fc->fs_private;
423	struct afs_super_info *as = AFS_FS_S(sb);
424
425	return (as->net_ns == fc->net_ns &&
426		as->volume &&
427		as->volume->vid == ctx->volume->vid &&
428		as->cell == ctx->cell &&
429		!as->dyn_root);
430}
431
432static int afs_dynroot_test_super(struct super_block *sb, struct fs_context *fc)
433{
434	struct afs_super_info *as = AFS_FS_S(sb);
435
436	return (as->net_ns == fc->net_ns &&
437		as->dyn_root);
438}
439
440static int afs_set_super(struct super_block *sb, struct fs_context *fc)
441{
442	return set_anon_super(sb, NULL);
443}
444
445/*
446 * fill in the superblock
447 */
448static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
449{
450	struct afs_super_info *as = AFS_FS_S(sb);
451	struct inode *inode = NULL;
452	int ret;
453
454	_enter("");
455
456	/* fill in the superblock */
457	sb->s_blocksize		= PAGE_SIZE;
458	sb->s_blocksize_bits	= PAGE_SHIFT;
459	sb->s_maxbytes		= MAX_LFS_FILESIZE;
460	sb->s_magic		= AFS_FS_MAGIC;
461	sb->s_op		= &afs_super_ops;
462	if (!as->dyn_root)
463		sb->s_xattr	= afs_xattr_handlers;
464	ret = super_setup_bdi(sb);
465	if (ret)
466		return ret;
467
468	/* allocate the root inode and dentry */
469	if (as->dyn_root) {
470		inode = afs_iget_pseudo_dir(sb, true);
471	} else {
472		sprintf(sb->s_id, "%llu", as->volume->vid);
473		afs_activate_volume(as->volume);
474		inode = afs_root_iget(sb, ctx->key);
475	}
476
477	if (IS_ERR(inode))
478		return PTR_ERR(inode);
479
480	if (ctx->autocell || as->dyn_root)
481		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
482
483	ret = -ENOMEM;
484	sb->s_root = d_make_root(inode);
485	if (!sb->s_root)
486		goto error;
487
488	if (as->dyn_root) {
489		sb->s_d_op = &afs_dynroot_dentry_operations;
490		ret = afs_dynroot_populate(sb);
491		if (ret < 0)
492			goto error;
493	} else {
494		sb->s_d_op = &afs_fs_dentry_operations;
495		rcu_assign_pointer(as->volume->sb, sb);
496	}
497
498	_leave(" = 0");
499	return 0;
500
501error:
502	_leave(" = %d", ret);
503	return ret;
504}
505
506static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
507{
508	struct afs_fs_context *ctx = fc->fs_private;
509	struct afs_super_info *as;
510
511	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
512	if (as) {
513		as->net_ns = get_net(fc->net_ns);
514		as->flock_mode = ctx->flock_mode;
515		if (ctx->dyn_root) {
516			as->dyn_root = true;
517		} else {
518			as->cell = afs_use_cell(ctx->cell, afs_cell_trace_use_sbi);
519			as->volume = afs_get_volume(ctx->volume,
520						    afs_volume_trace_get_alloc_sbi);
521		}
522	}
523	return as;
524}
525
526static void afs_destroy_sbi(struct afs_super_info *as)
527{
528	if (as) {
529		struct afs_net *net = afs_net(as->net_ns);
530		afs_put_volume(net, as->volume, afs_volume_trace_put_destroy_sbi);
531		afs_unuse_cell(net, as->cell, afs_cell_trace_unuse_sbi);
532		put_net(as->net_ns);
533		kfree(as);
534	}
535}
536
537static void afs_kill_super(struct super_block *sb)
538{
539	struct afs_super_info *as = AFS_FS_S(sb);
540
541	if (as->dyn_root)
542		afs_dynroot_depopulate(sb);
543
544	/* Clear the callback interests (which will do ilookup5) before
545	 * deactivating the superblock.
546	 */
547	if (as->volume)
548		rcu_assign_pointer(as->volume->sb, NULL);
549	kill_anon_super(sb);
550	if (as->volume)
551		afs_deactivate_volume(as->volume);
552	afs_destroy_sbi(as);
553}
554
555/*
556 * Get an AFS superblock and root directory.
557 */
558static int afs_get_tree(struct fs_context *fc)
559{
560	struct afs_fs_context *ctx = fc->fs_private;
561	struct super_block *sb;
562	struct afs_super_info *as;
563	int ret;
564
565	ret = afs_validate_fc(fc);
566	if (ret)
567		goto error;
568
569	_enter("");
570
571	/* allocate a superblock info record */
572	ret = -ENOMEM;
573	as = afs_alloc_sbi(fc);
574	if (!as)
575		goto error;
576	fc->s_fs_info = as;
577
578	/* allocate a deviceless superblock */
579	sb = sget_fc(fc,
580		     as->dyn_root ? afs_dynroot_test_super : afs_test_super,
581		     afs_set_super);
582	if (IS_ERR(sb)) {
583		ret = PTR_ERR(sb);
584		goto error;
585	}
586
587	if (!sb->s_root) {
588		/* initial superblock/root creation */
589		_debug("create");
590		ret = afs_fill_super(sb, ctx);
591		if (ret < 0)
592			goto error_sb;
593		sb->s_flags |= SB_ACTIVE;
594	} else {
595		_debug("reuse");
596		ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
597	}
598
599	fc->root = dget(sb->s_root);
600	trace_afs_get_tree(as->cell, as->volume);
601	_leave(" = 0 [%p]", sb);
602	return 0;
603
604error_sb:
605	deactivate_locked_super(sb);
606error:
607	_leave(" = %d", ret);
608	return ret;
609}
610
611static void afs_free_fc(struct fs_context *fc)
612{
613	struct afs_fs_context *ctx = fc->fs_private;
614
615	afs_destroy_sbi(fc->s_fs_info);
616	afs_put_volume(ctx->net, ctx->volume, afs_volume_trace_put_free_fc);
617	afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
618	key_put(ctx->key);
619	kfree(ctx);
620}
621
622static const struct fs_context_operations afs_context_ops = {
623	.free		= afs_free_fc,
624	.parse_param	= afs_parse_param,
625	.get_tree	= afs_get_tree,
626};
627
628/*
629 * Set up the filesystem mount context.
630 */
631static int afs_init_fs_context(struct fs_context *fc)
632{
633	struct afs_fs_context *ctx;
634	struct afs_cell *cell;
635
636	ctx = kzalloc(sizeof(struct afs_fs_context), GFP_KERNEL);
637	if (!ctx)
638		return -ENOMEM;
639
640	ctx->type = AFSVL_ROVOL;
641	ctx->net = afs_net(fc->net_ns);
642
643	/* Default to the workstation cell. */
644	cell = afs_find_cell(ctx->net, NULL, 0, afs_cell_trace_use_fc);
645	if (IS_ERR(cell))
646		cell = NULL;
647	ctx->cell = cell;
648
649	fc->fs_private = ctx;
650	fc->ops = &afs_context_ops;
651	return 0;
652}
653
654/*
655 * Initialise an inode cache slab element prior to any use.  Note that
656 * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
657 * inode to another.
658 */
659static void afs_i_init_once(void *_vnode)
660{
661	struct afs_vnode *vnode = _vnode;
662
663	memset(vnode, 0, sizeof(*vnode));
664	inode_init_once(&vnode->netfs.inode);
665	mutex_init(&vnode->io_lock);
666	init_rwsem(&vnode->validate_lock);
667	spin_lock_init(&vnode->wb_lock);
668	spin_lock_init(&vnode->lock);
669	INIT_LIST_HEAD(&vnode->wb_keys);
670	INIT_LIST_HEAD(&vnode->pending_locks);
671	INIT_LIST_HEAD(&vnode->granted_locks);
672	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
673	INIT_LIST_HEAD(&vnode->cb_mmap_link);
674	seqlock_init(&vnode->cb_lock);
675}
676
677/*
678 * allocate an AFS inode struct from our slab cache
679 */
680static struct inode *afs_alloc_inode(struct super_block *sb)
681{
682	struct afs_vnode *vnode;
683
684	vnode = alloc_inode_sb(sb, afs_inode_cachep, GFP_KERNEL);
685	if (!vnode)
686		return NULL;
687
688	atomic_inc(&afs_count_active_inodes);
689
690	/* Reset anything that shouldn't leak from one inode to the next. */
691	memset(&vnode->fid, 0, sizeof(vnode->fid));
692	memset(&vnode->status, 0, sizeof(vnode->status));
693	afs_vnode_set_cache(vnode, NULL);
694
695	vnode->volume		= NULL;
696	vnode->lock_key		= NULL;
697	vnode->permit_cache	= NULL;
698
699	vnode->flags		= 1 << AFS_VNODE_UNSET;
700	vnode->lock_state	= AFS_VNODE_LOCK_NONE;
701
702	init_rwsem(&vnode->rmdir_lock);
703	INIT_WORK(&vnode->cb_work, afs_invalidate_mmap_work);
704
705	_leave(" = %p", &vnode->netfs.inode);
706	return &vnode->netfs.inode;
707}
708
709static void afs_free_inode(struct inode *inode)
710{
711	kmem_cache_free(afs_inode_cachep, AFS_FS_I(inode));
712}
713
714/*
715 * destroy an AFS inode struct
716 */
717static void afs_destroy_inode(struct inode *inode)
718{
719	struct afs_vnode *vnode = AFS_FS_I(inode);
720
721	_enter("%p{%llx:%llu}", inode, vnode->fid.vid, vnode->fid.vnode);
722
723	_debug("DESTROY INODE %p", inode);
724
725	atomic_dec(&afs_count_active_inodes);
726}
727
728static void afs_get_volume_status_success(struct afs_operation *op)
729{
730	struct afs_volume_status *vs = &op->volstatus.vs;
731	struct kstatfs *buf = op->volstatus.buf;
732
733	if (vs->max_quota == 0)
734		buf->f_blocks = vs->part_max_blocks;
735	else
736		buf->f_blocks = vs->max_quota;
737
738	if (buf->f_blocks > vs->blocks_in_use)
739		buf->f_bavail = buf->f_bfree =
740			buf->f_blocks - vs->blocks_in_use;
741}
742
743static const struct afs_operation_ops afs_get_volume_status_operation = {
744	.issue_afs_rpc	= afs_fs_get_volume_status,
745	.issue_yfs_rpc	= yfs_fs_get_volume_status,
746	.success	= afs_get_volume_status_success,
747};
748
749/*
750 * return information about an AFS volume
751 */
752static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
753{
754	struct afs_super_info *as = AFS_FS_S(dentry->d_sb);
755	struct afs_operation *op;
756	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
757
758	buf->f_type	= dentry->d_sb->s_magic;
759	buf->f_bsize	= AFS_BLOCK_SIZE;
760	buf->f_namelen	= AFSNAMEMAX - 1;
761
762	if (as->dyn_root) {
763		buf->f_blocks	= 1;
764		buf->f_bavail	= 0;
765		buf->f_bfree	= 0;
766		return 0;
767	}
768
769	op = afs_alloc_operation(NULL, as->volume);
770	if (IS_ERR(op))
771		return PTR_ERR(op);
772
773	afs_op_set_vnode(op, 0, vnode);
774	op->nr_files		= 1;
775	op->volstatus.buf	= buf;
776	op->ops			= &afs_get_volume_status_operation;
777	return afs_do_sync_operation(op);
778}
779