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(v: &afs_count_active_inodes, i: 0);
104
105 ret = -ENOMEM;
106 afs_inode_cachep = kmem_cache_create(name: "afs_inode_cache",
107 size: sizeof(struct afs_vnode),
108 align: 0,
109 SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
110 ctor: 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(s: 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(v: &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(s: 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(sb: 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, s: "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, fmt: "%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(sb: root->d_sb);
193 const char *p = NULL;
194
195 if (as->dyn_root)
196 seq_puts(m, s: ",dyn");
197 if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
198 seq_puts(m, s: ",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, fmt: ",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(ptr: cell)) {
297 pr_err("kAFS: unable to lookup cell '%*.*s'\n",
298 cellnamesz, cellnamesz, cellname ?: "");
299 return PTR_ERR(ptr: 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, desc: afs_fs_parameters, param, result: &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(ptr: key))
379 return PTR_ERR(ptr: 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(key: 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(ptr: volume))
407 return PTR_ERR(ptr: volume);
408
409 ctx->volume = volume;
410 }
411
412 return 0;
413}
414
415/*
416 * check a superblock to see if it's the one we're looking for
417 */
418static int afs_test_super(struct super_block *sb, struct fs_context *fc)
419{
420 struct afs_fs_context *ctx = fc->fs_private;
421 struct afs_super_info *as = AFS_FS_S(sb);
422
423 return (as->net_ns == fc->net_ns &&
424 as->volume &&
425 as->volume->vid == ctx->volume->vid &&
426 as->cell == ctx->cell &&
427 !as->dyn_root);
428}
429
430static int afs_dynroot_test_super(struct super_block *sb, struct fs_context *fc)
431{
432 struct afs_super_info *as = AFS_FS_S(sb);
433
434 return (as->net_ns == fc->net_ns &&
435 as->dyn_root);
436}
437
438static int afs_set_super(struct super_block *sb, struct fs_context *fc)
439{
440 return set_anon_super(s: sb, NULL);
441}
442
443/*
444 * fill in the superblock
445 */
446static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
447{
448 struct afs_super_info *as = AFS_FS_S(sb);
449 struct inode *inode = NULL;
450 int ret;
451
452 _enter("");
453
454 /* fill in the superblock */
455 sb->s_blocksize = PAGE_SIZE;
456 sb->s_blocksize_bits = PAGE_SHIFT;
457 sb->s_maxbytes = MAX_LFS_FILESIZE;
458 sb->s_magic = AFS_FS_MAGIC;
459 sb->s_op = &afs_super_ops;
460 if (!as->dyn_root)
461 sb->s_xattr = afs_xattr_handlers;
462 ret = super_setup_bdi(sb);
463 if (ret)
464 return ret;
465
466 /* allocate the root inode and dentry */
467 if (as->dyn_root) {
468 inode = afs_iget_pseudo_dir(sb, true);
469 } else {
470 sprintf(buf: sb->s_id, fmt: "%llu", as->volume->vid);
471 afs_activate_volume(as->volume);
472 inode = afs_root_iget(sb, ctx->key);
473 }
474
475 if (IS_ERR(ptr: inode))
476 return PTR_ERR(ptr: inode);
477
478 if (ctx->autocell || as->dyn_root)
479 set_bit(AFS_VNODE_AUTOCELL, addr: &AFS_FS_I(inode)->flags);
480
481 ret = -ENOMEM;
482 sb->s_root = d_make_root(inode);
483 if (!sb->s_root)
484 goto error;
485
486 if (as->dyn_root) {
487 sb->s_d_op = &afs_dynroot_dentry_operations;
488 ret = afs_dynroot_populate(sb);
489 if (ret < 0)
490 goto error;
491 } else {
492 sb->s_d_op = &afs_fs_dentry_operations;
493 rcu_assign_pointer(as->volume->sb, sb);
494 }
495
496 _leave(" = 0");
497 return 0;
498
499error:
500 _leave(" = %d", ret);
501 return ret;
502}
503
504static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
505{
506 struct afs_fs_context *ctx = fc->fs_private;
507 struct afs_super_info *as;
508
509 as = kzalloc(size: sizeof(struct afs_super_info), GFP_KERNEL);
510 if (as) {
511 as->net_ns = get_net(net: fc->net_ns);
512 as->flock_mode = ctx->flock_mode;
513 if (ctx->dyn_root) {
514 as->dyn_root = true;
515 } else {
516 as->cell = afs_use_cell(ctx->cell, afs_cell_trace_use_sbi);
517 as->volume = afs_get_volume(ctx->volume,
518 afs_volume_trace_get_alloc_sbi);
519 }
520 }
521 return as;
522}
523
524static void afs_destroy_sbi(struct afs_super_info *as)
525{
526 if (as) {
527 struct afs_net *net = afs_net(net: as->net_ns);
528 afs_put_volume(net, as->volume, afs_volume_trace_put_destroy_sbi);
529 afs_unuse_cell(net, as->cell, afs_cell_trace_unuse_sbi);
530 put_net(net: as->net_ns);
531 kfree(objp: as);
532 }
533}
534
535static void afs_kill_super(struct super_block *sb)
536{
537 struct afs_super_info *as = AFS_FS_S(sb);
538
539 if (as->dyn_root)
540 afs_dynroot_depopulate(sb);
541
542 /* Clear the callback interests (which will do ilookup5) before
543 * deactivating the superblock.
544 */
545 if (as->volume)
546 rcu_assign_pointer(as->volume->sb, NULL);
547 kill_anon_super(sb);
548 if (as->volume)
549 afs_deactivate_volume(as->volume);
550 afs_destroy_sbi(as);
551}
552
553/*
554 * Get an AFS superblock and root directory.
555 */
556static int afs_get_tree(struct fs_context *fc)
557{
558 struct afs_fs_context *ctx = fc->fs_private;
559 struct super_block *sb;
560 struct afs_super_info *as;
561 int ret;
562
563 ret = afs_validate_fc(fc);
564 if (ret)
565 goto error;
566
567 _enter("");
568
569 /* allocate a superblock info record */
570 ret = -ENOMEM;
571 as = afs_alloc_sbi(fc);
572 if (!as)
573 goto error;
574 fc->s_fs_info = as;
575
576 /* allocate a deviceless superblock */
577 sb = sget_fc(fc,
578 test: as->dyn_root ? afs_dynroot_test_super : afs_test_super,
579 set: afs_set_super);
580 if (IS_ERR(ptr: sb)) {
581 ret = PTR_ERR(ptr: sb);
582 goto error;
583 }
584
585 if (!sb->s_root) {
586 /* initial superblock/root creation */
587 _debug("create");
588 ret = afs_fill_super(sb, ctx);
589 if (ret < 0)
590 goto error_sb;
591 sb->s_flags |= SB_ACTIVE;
592 } else {
593 _debug("reuse");
594 ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
595 }
596
597 fc->root = dget(dentry: sb->s_root);
598 trace_afs_get_tree(cell: as->cell, volume: as->volume);
599 _leave(" = 0 [%p]", sb);
600 return 0;
601
602error_sb:
603 deactivate_locked_super(sb);
604error:
605 _leave(" = %d", ret);
606 return ret;
607}
608
609static void afs_free_fc(struct fs_context *fc)
610{
611 struct afs_fs_context *ctx = fc->fs_private;
612
613 afs_destroy_sbi(as: fc->s_fs_info);
614 afs_put_volume(ctx->net, ctx->volume, afs_volume_trace_put_free_fc);
615 afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
616 key_put(key: ctx->key);
617 kfree(objp: ctx);
618}
619
620static const struct fs_context_operations afs_context_ops = {
621 .free = afs_free_fc,
622 .parse_param = afs_parse_param,
623 .get_tree = afs_get_tree,
624};
625
626/*
627 * Set up the filesystem mount context.
628 */
629static int afs_init_fs_context(struct fs_context *fc)
630{
631 struct afs_fs_context *ctx;
632 struct afs_cell *cell;
633
634 ctx = kzalloc(size: sizeof(struct afs_fs_context), GFP_KERNEL);
635 if (!ctx)
636 return -ENOMEM;
637
638 ctx->type = AFSVL_ROVOL;
639 ctx->net = afs_net(net: fc->net_ns);
640
641 /* Default to the workstation cell. */
642 cell = afs_find_cell(ctx->net, NULL, 0, afs_cell_trace_use_fc);
643 if (IS_ERR(ptr: cell))
644 cell = NULL;
645 ctx->cell = cell;
646
647 fc->fs_private = ctx;
648 fc->ops = &afs_context_ops;
649 return 0;
650}
651
652/*
653 * Initialise an inode cache slab element prior to any use. Note that
654 * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
655 * inode to another.
656 */
657static void afs_i_init_once(void *_vnode)
658{
659 struct afs_vnode *vnode = _vnode;
660
661 memset(vnode, 0, sizeof(*vnode));
662 inode_init_once(&vnode->netfs.inode);
663 mutex_init(&vnode->io_lock);
664 init_rwsem(&vnode->validate_lock);
665 spin_lock_init(&vnode->wb_lock);
666 spin_lock_init(&vnode->lock);
667 INIT_LIST_HEAD(list: &vnode->wb_keys);
668 INIT_LIST_HEAD(list: &vnode->pending_locks);
669 INIT_LIST_HEAD(list: &vnode->granted_locks);
670 INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
671 INIT_LIST_HEAD(list: &vnode->cb_mmap_link);
672 seqlock_init(&vnode->cb_lock);
673}
674
675/*
676 * allocate an AFS inode struct from our slab cache
677 */
678static struct inode *afs_alloc_inode(struct super_block *sb)
679{
680 struct afs_vnode *vnode;
681
682 vnode = alloc_inode_sb(sb, cache: afs_inode_cachep, GFP_KERNEL);
683 if (!vnode)
684 return NULL;
685
686 atomic_inc(v: &afs_count_active_inodes);
687
688 /* Reset anything that shouldn't leak from one inode to the next. */
689 memset(&vnode->fid, 0, sizeof(vnode->fid));
690 memset(&vnode->status, 0, sizeof(vnode->status));
691 afs_vnode_set_cache(vnode, NULL);
692
693 vnode->volume = NULL;
694 vnode->lock_key = NULL;
695 vnode->permit_cache = NULL;
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->netfs.inode);
704 return &vnode->netfs.inode;
705}
706
707static void afs_free_inode(struct inode *inode)
708{
709 kmem_cache_free(s: afs_inode_cachep, objp: AFS_FS_I(inode));
710}
711
712/*
713 * destroy an AFS inode struct
714 */
715static 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(v: &afs_count_active_inodes);
724}
725
726static 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
741static 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 */
750static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
751{
752 struct afs_super_info *as = AFS_FS_S(sb: dentry->d_sb);
753 struct afs_operation *op;
754 struct afs_vnode *vnode = AFS_FS_I(inode: 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(ptr: op))
769 return PTR_ERR(ptr: op);
770
771 afs_op_set_vnode(op, n: 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

source code of linux/fs/afs/super.c