super.c

  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	= netfs_unpin_writeback,
 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	switch (as->flock_mode) {
198	case afs_flock_mode_unset:	break;
199	case afs_flock_mode_local:	p = "local";	break;
200	case afs_flock_mode_openafs:	p = "openafs";	break;
201	case afs_flock_mode_strict:	p = "strict";	break;
202	case afs_flock_mode_write:	p = "write";	break;
203	}
204	if (p)
205		seq_printf(m, ",flock=%s", p);
206
207	return 0;
208}
209
210/*
211 * Parse the source name to get cell name, volume name, volume type and R/W
212 * selector.
213 *
214 * This can be one of the following:
215 *	"%[cell:]volume[.]"		R/W volume
216 *	"#[cell:]volume[.]"		R/O or R/W volume (R/O parent),
217 *					 or R/W (R/W parent) volume
218 *	"%[cell:]volume.readonly"	R/O volume
219 *	"#[cell:]volume.readonly"	R/O volume
220 *	"%[cell:]volume.backup"		Backup volume
221 *	"#[cell:]volume.backup"		Backup volume
222 */
223static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
224{
225	struct afs_fs_context *ctx = fc->fs_private;
226	struct afs_cell *cell;
227	const char *cellname, *suffix, *name = param->string;
228	int cellnamesz;
229
230	_enter(",%s", name);
231
232	if (fc->source)
233		return invalf(fc, "kAFS: Multiple sources not supported");
234
235	if (!name) {
236		printk(KERN_ERR "kAFS: no volume name specified\n");
237		return -EINVAL;
238	}
239
240	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
241		/* To use dynroot, we don't want to have to provide a source */
242		if (strcmp(name, "none") == 0) {
243			ctx->no_cell = true;
244			return 0;
245		}
246		printk(KERN_ERR "kAFS: unparsable volume name\n");
247		return -EINVAL;
248	}
249
250	/* determine the type of volume we're looking for */
251	if (name[0] == '%') {
252		ctx->type = AFSVL_RWVOL;
253		ctx->force = true;
254	}
255	name++;
256
257	/* split the cell name out if there is one */
258	ctx->volname = strchr(name, ':');
259	if (ctx->volname) {
260		cellname = name;
261		cellnamesz = ctx->volname - name;
262		ctx->volname++;
263	} else {
264		ctx->volname = name;
265		cellname = NULL;
266		cellnamesz = 0;
267	}
268
269	/* the volume type is further affected by a possible suffix */
270	suffix = strrchr(ctx->volname, '.');
271	if (suffix) {
272		if (strcmp(suffix, ".readonly") == 0) {
273			ctx->type = AFSVL_ROVOL;
274			ctx->force = true;
275		} else if (strcmp(suffix, ".backup") == 0) {
276			ctx->type = AFSVL_BACKVOL;
277			ctx->force = true;
278		} else if (suffix[1] == 0) {
279		} else {
280			suffix = NULL;
281		}
282	}
283
284	ctx->volnamesz = suffix ?
285		suffix - ctx->volname : strlen(ctx->volname);
286
287	_debug("cell %*.*s [%p]",
288	       cellnamesz, cellnamesz, cellname ?: "", ctx->cell);
289
290	/* lookup the cell record */
291	if (cellname) {
292		cell = afs_lookup_cell(ctx->net, cellname, cellnamesz,
293				       NULL, AFS_LOOKUP_CELL_DIRECT_MOUNT,
294				       afs_cell_trace_use_lookup_mount);
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->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 */
318static 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 */
355static 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->volume, afs_volume_trace_put_validate_fc);
384			ctx->volume = NULL;
385		}
386
387		if (test_bit(AFS_CELL_FL_CHECK_ALIAS, &ctx->cell->flags)) {
388			ret = afs_cell_detect_alias(ctx->cell, key);
389			if (ret < 0)
390				return ret;
391			if (ret == 1) {
392				_debug("switch to alias");
393				key_put(ctx->key);
394				ctx->key = NULL;
395				cell = afs_use_cell(ctx->cell->alias_of,
396						    afs_cell_trace_use_fc_alias);
397				afs_unuse_cell(ctx->cell, afs_cell_trace_unuse_fc);
398				ctx->cell = cell;
399				goto reget_key;
400			}
401		}
402
403		volume = afs_create_volume(ctx);
404		if (IS_ERR(volume))
405			return PTR_ERR(volume);
406
407		ctx->volume = volume;
408		if (volume->type != AFSVL_RWVOL) {
409			ctx->flock_mode = afs_flock_mode_local;
410			fc->sb_flags |= SB_RDONLY;
411		}
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_dynroot_iget_root(sb);
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	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		set_default_d_op(sb, &afs_dynroot_dentry_operations);
487	} else {
488		set_default_d_op(sb, &afs_fs_dentry_operations);
489		rcu_assign_pointer(as->volume->sb, sb);
490	}
491
492	_leave(" = 0");
493	return 0;
494
495error:
496	_leave(" = %d", ret);
497	return ret;
498}
499
500static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
501{
502	struct afs_fs_context *ctx = fc->fs_private;
503	struct afs_super_info *as;
504
505	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
506	if (as) {
507		as->net_ns = get_net(fc->net_ns);
508		as->flock_mode = ctx->flock_mode;
509		if (ctx->dyn_root) {
510			as->dyn_root = true;
511		} else {
512			as->cell = afs_use_cell(ctx->cell, afs_cell_trace_use_sbi);
513			as->volume = afs_get_volume(ctx->volume,
514						    afs_volume_trace_get_alloc_sbi);
515		}
516	}
517	return as;
518}
519
520static void afs_destroy_sbi(struct afs_super_info *as)
521{
522	if (as) {
523		afs_put_volume(as->volume, afs_volume_trace_put_destroy_sbi);
524		afs_unuse_cell(as->cell, afs_cell_trace_unuse_sbi);
525		put_net(as->net_ns);
526		kfree(as);
527	}
528}
529
530static void afs_kill_super(struct super_block *sb)
531{
532	struct afs_super_info *as = AFS_FS_S(sb);
533
534	/* Clear the callback interests (which will do ilookup5) before
535	 * deactivating the superblock.
536	 */
537	if (as->volume)
538		rcu_assign_pointer(as->volume->sb, NULL);
539	kill_anon_super(sb);
540	if (as->volume)
541		afs_deactivate_volume(as->volume);
542	afs_destroy_sbi(as);
543}
544
545/*
546 * Get an AFS superblock and root directory.
547 */
548static int afs_get_tree(struct fs_context *fc)
549{
550	struct afs_fs_context *ctx = fc->fs_private;
551	struct super_block *sb;
552	struct afs_super_info *as;
553	int ret;
554
555	ret = afs_validate_fc(fc);
556	if (ret)
557		goto error;
558
559	_enter("");
560
561	/* allocate a superblock info record */
562	ret = -ENOMEM;
563	as = afs_alloc_sbi(fc);
564	if (!as)
565		goto error;
566	fc->s_fs_info = as;
567
568	/* allocate a deviceless superblock */
569	sb = sget_fc(fc,
570		     as->dyn_root ? afs_dynroot_test_super : afs_test_super,
571		     afs_set_super);
572	if (IS_ERR(sb)) {
573		ret = PTR_ERR(sb);
574		goto error;
575	}
576
577	if (!sb->s_root) {
578		/* initial superblock/root creation */
579		_debug("create");
580		ret = afs_fill_super(sb, ctx);
581		if (ret < 0)
582			goto error_sb;
583		sb->s_flags |= SB_ACTIVE;
584	} else {
585		_debug("reuse");
586		ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
587	}
588
589	fc->root = dget(sb->s_root);
590	trace_afs_get_tree(as->cell, as->volume);
591	_leave(" = 0 [%p]", sb);
592	return 0;
593
594error_sb:
595	deactivate_locked_super(sb);
596error:
597	_leave(" = %d", ret);
598	return ret;
599}
600
601static void afs_free_fc(struct fs_context *fc)
602{
603	struct afs_fs_context *ctx = fc->fs_private;
604
605	afs_destroy_sbi(fc->s_fs_info);
606	afs_put_volume(ctx->volume, afs_volume_trace_put_free_fc);
607	afs_unuse_cell(ctx->cell, afs_cell_trace_unuse_fc);
608	key_put(ctx->key);
609	kfree(ctx);
610}
611
612static const struct fs_context_operations afs_context_ops = {
613	.free		= afs_free_fc,
614	.parse_param	= afs_parse_param,
615	.get_tree	= afs_get_tree,
616};
617
618/*
619 * Set up the filesystem mount context.
620 */
621static int afs_init_fs_context(struct fs_context *fc)
622{
623	struct afs_fs_context *ctx;
624	struct afs_cell *cell;
625
626	ctx = kzalloc(sizeof(struct afs_fs_context), GFP_KERNEL);
627	if (!ctx)
628		return -ENOMEM;
629
630	ctx->type = AFSVL_ROVOL;
631	ctx->net = afs_net(fc->net_ns);
632
633	/* Default to the workstation cell. */
634	cell = afs_find_cell(ctx->net, NULL, 0, afs_cell_trace_use_fc);
635	if (IS_ERR(cell))
636		cell = NULL;
637	ctx->cell = cell;
638
639	fc->fs_private = ctx;
640	fc->ops = &afs_context_ops;
641	return 0;
642}
643
644/*
645 * Initialise an inode cache slab element prior to any use.  Note that
646 * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
647 * inode to another.
648 */
649static void afs_i_init_once(void *_vnode)
650{
651	struct afs_vnode *vnode = _vnode;
652
653	memset(vnode, 0, sizeof(*vnode));
654	inode_init_once(&vnode->netfs.inode);
655	INIT_LIST_HEAD(&vnode->io_lock_waiters);
656	init_rwsem(&vnode->validate_lock);
657	spin_lock_init(&vnode->wb_lock);
658	spin_lock_init(&vnode->lock);
659	INIT_LIST_HEAD(&vnode->wb_keys);
660	INIT_LIST_HEAD(&vnode->pending_locks);
661	INIT_LIST_HEAD(&vnode->granted_locks);
662	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
663	INIT_LIST_HEAD(&vnode->cb_mmap_link);
664	seqlock_init(&vnode->cb_lock);
665}
666
667/*
668 * allocate an AFS inode struct from our slab cache
669 */
670static struct inode *afs_alloc_inode(struct super_block *sb)
671{
672	struct afs_vnode *vnode;
673
674	vnode = alloc_inode_sb(sb, afs_inode_cachep, GFP_KERNEL);
675	if (!vnode)
676		return NULL;
677
678	atomic_inc(&afs_count_active_inodes);
679
680	/* Reset anything that shouldn't leak from one inode to the next. */
681	memset(&vnode->fid, 0, sizeof(vnode->fid));
682	memset(&vnode->status, 0, sizeof(vnode->status));
683	afs_vnode_set_cache(vnode, NULL);
684
685	vnode->volume		= NULL;
686	vnode->lock_key		= NULL;
687	vnode->permit_cache	= NULL;
688	vnode->directory	= NULL;
689	vnode->directory_size	= 0;
690
691	vnode->flags		= 1 << AFS_VNODE_UNSET;
692	vnode->lock_state	= AFS_VNODE_LOCK_NONE;
693
694	init_rwsem(&vnode->rmdir_lock);
695	INIT_WORK(&vnode->cb_work, afs_invalidate_mmap_work);
696
697	_leave(" = %p", &vnode->netfs.inode);
698	return &vnode->netfs.inode;
699}
700
701static void afs_free_inode(struct inode *inode)
702{
703	kmem_cache_free(afs_inode_cachep, AFS_FS_I(inode));
704}
705
706/*
707 * destroy an AFS inode struct
708 */
709static void afs_destroy_inode(struct inode *inode)
710{
711	struct afs_vnode *vnode = AFS_FS_I(inode);
712
713	_enter("%p{%llx:%llu}", inode, vnode->fid.vid, vnode->fid.vnode);
714
715	_debug("DESTROY INODE %p", inode);
716
717	atomic_dec(&afs_count_active_inodes);
718}
719
720static void afs_get_volume_status_success(struct afs_operation *op)
721{
722	struct afs_volume_status *vs = &op->volstatus.vs;
723	struct kstatfs *buf = op->volstatus.buf;
724
725	if (vs->max_quota == 0)
726		buf->f_blocks = vs->part_max_blocks;
727	else
728		buf->f_blocks = vs->max_quota;
729
730	if (buf->f_blocks > vs->blocks_in_use)
731		buf->f_bavail = buf->f_bfree =
732			buf->f_blocks - vs->blocks_in_use;
733}
734
735static const struct afs_operation_ops afs_get_volume_status_operation = {
736	.issue_afs_rpc	= afs_fs_get_volume_status,
737	.issue_yfs_rpc	= yfs_fs_get_volume_status,
738	.success	= afs_get_volume_status_success,
739};
740
741/*
742 * return information about an AFS volume
743 */
744static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
745{
746	struct afs_super_info *as = AFS_FS_S(dentry->d_sb);
747	struct afs_operation *op;
748	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
749
750	buf->f_type	= dentry->d_sb->s_magic;
751	buf->f_bsize	= AFS_BLOCK_SIZE;
752	buf->f_namelen	= AFSNAMEMAX - 1;
753
754	if (as->dyn_root) {
755		buf->f_blocks	= 1;
756		buf->f_bavail	= 0;
757		buf->f_bfree	= 0;
758		return 0;
759	}
760
761	op = afs_alloc_operation(NULL, as->volume);
762	if (IS_ERR(op))
763		return PTR_ERR(op);
764
765	afs_op_set_vnode(op, 0, vnode);
766	op->nr_files		= 1;
767	op->volstatus.buf	= buf;
768	op->ops			= &afs_get_volume_status_operation;
769	return afs_do_sync_operation(op);
770}