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Linux/fs/afs/super.c

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  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@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/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 struct dentry *afs_mount(struct file_system_type *fs_type,
 34                       int flags, const char *dev_name, void *data);
 35 static void afs_kill_super(struct super_block *sb);
 36 static struct inode *afs_alloc_inode(struct super_block *sb);
 37 static void afs_destroy_inode(struct inode *inode);
 38 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
 39 static int afs_show_devname(struct seq_file *m, struct dentry *root);
 40 static int afs_show_options(struct seq_file *m, struct dentry *root);
 41 
 42 struct file_system_type afs_fs_type = {
 43         .owner          = THIS_MODULE,
 44         .name           = "afs",
 45         .mount          = afs_mount,
 46         .kill_sb        = afs_kill_super,
 47         .fs_flags       = 0,
 48 };
 49 MODULE_ALIAS_FS("afs");
 50 
 51 static const struct super_operations afs_super_ops = {
 52         .statfs         = afs_statfs,
 53         .alloc_inode    = afs_alloc_inode,
 54         .drop_inode     = afs_drop_inode,
 55         .destroy_inode  = afs_destroy_inode,
 56         .evict_inode    = afs_evict_inode,
 57         .show_devname   = afs_show_devname,
 58         .show_options   = afs_show_options,
 59 };
 60 
 61 static struct kmem_cache *afs_inode_cachep;
 62 static atomic_t afs_count_active_inodes;
 63 
 64 enum {
 65         afs_no_opt,
 66         afs_opt_cell,
 67         afs_opt_rwpath,
 68         afs_opt_vol,
 69         afs_opt_autocell,
 70 };
 71 
 72 static const match_table_t afs_options_list = {
 73         { afs_opt_cell,         "cell=%s"       },
 74         { afs_opt_rwpath,       "rwpath"        },
 75         { afs_opt_vol,          "vol=%s"        },
 76         { afs_opt_autocell,     "autocell"      },
 77         { afs_no_opt,           NULL            },
 78 };
 79 
 80 /*
 81  * initialise the filesystem
 82  */
 83 int __init afs_fs_init(void)
 84 {
 85         int ret;
 86 
 87         _enter("");
 88 
 89         /* create ourselves an inode cache */
 90         atomic_set(&afs_count_active_inodes, 0);
 91 
 92         ret = -ENOMEM;
 93         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
 94                                              sizeof(struct afs_vnode),
 95                                              0,
 96                                              SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
 97                                              afs_i_init_once);
 98         if (!afs_inode_cachep) {
 99                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
100                 return ret;
101         }
102 
103         /* now export our filesystem to lesser mortals */
104         ret = register_filesystem(&afs_fs_type);
105         if (ret < 0) {
106                 kmem_cache_destroy(afs_inode_cachep);
107                 _leave(" = %d", ret);
108                 return ret;
109         }
110 
111         _leave(" = 0");
112         return 0;
113 }
114 
115 /*
116  * clean up the filesystem
117  */
118 void __exit afs_fs_exit(void)
119 {
120         _enter("");
121 
122         afs_mntpt_kill_timer();
123         unregister_filesystem(&afs_fs_type);
124 
125         if (atomic_read(&afs_count_active_inodes) != 0) {
126                 printk("kAFS: %d active inode objects still present\n",
127                        atomic_read(&afs_count_active_inodes));
128                 BUG();
129         }
130 
131         /*
132          * Make sure all delayed rcu free inodes are flushed before we
133          * destroy cache.
134          */
135         rcu_barrier();
136         kmem_cache_destroy(afs_inode_cachep);
137         _leave("");
138 }
139 
140 /*
141  * Display the mount device name in /proc/mounts.
142  */
143 static int afs_show_devname(struct seq_file *m, struct dentry *root)
144 {
145         struct afs_super_info *as = AFS_FS_S(root->d_sb);
146         struct afs_volume *volume = as->volume;
147         struct afs_cell *cell = as->cell;
148         const char *suf = "";
149         char pref = '%';
150 
151         switch (volume->type) {
152         case AFSVL_RWVOL:
153                 break;
154         case AFSVL_ROVOL:
155                 pref = '#';
156                 if (volume->type_force)
157                         suf = ".readonly";
158                 break;
159         case AFSVL_BACKVOL:
160                 pref = '#';
161                 suf = ".backup";
162                 break;
163         }
164 
165         seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
166         return 0;
167 }
168 
169 /*
170  * Display the mount options in /proc/mounts.
171  */
172 static int afs_show_options(struct seq_file *m, struct dentry *root)
173 {
174         if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
175                 seq_puts(m, "autocell");
176         return 0;
177 }
178 
179 /*
180  * parse the mount options
181  * - this function has been shamelessly adapted from the ext3 fs which
182  *   shamelessly adapted it from the msdos fs
183  */
184 static int afs_parse_options(struct afs_mount_params *params,
185                              char *options, const char **devname)
186 {
187         struct afs_cell *cell;
188         substring_t args[MAX_OPT_ARGS];
189         char *p;
190         int token;
191 
192         _enter("%s", options);
193 
194         options[PAGE_SIZE - 1] = 0;
195 
196         while ((p = strsep(&options, ","))) {
197                 if (!*p)
198                         continue;
199 
200                 token = match_token(p, afs_options_list, args);
201                 switch (token) {
202                 case afs_opt_cell:
203                         rcu_read_lock();
204                         cell = afs_lookup_cell_rcu(params->net,
205                                                    args[0].from,
206                                                    args[0].to - args[0].from);
207                         rcu_read_unlock();
208                         if (IS_ERR(cell))
209                                 return PTR_ERR(cell);
210                         afs_put_cell(params->net, params->cell);
211                         params->cell = cell;
212                         break;
213 
214                 case afs_opt_rwpath:
215                         params->rwpath = 1;
216                         break;
217 
218                 case afs_opt_vol:
219                         *devname = args[0].from;
220                         break;
221 
222                 case afs_opt_autocell:
223                         params->autocell = 1;
224                         break;
225 
226                 default:
227                         printk(KERN_ERR "kAFS:"
228                                " Unknown or invalid mount option: '%s'\n", p);
229                         return -EINVAL;
230                 }
231         }
232 
233         _leave(" = 0");
234         return 0;
235 }
236 
237 /*
238  * parse a device name to get cell name, volume name, volume type and R/W
239  * selector
240  * - this can be one of the following:
241  *      "%[cell:]volume[.]"             R/W volume
242  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
243  *                                       or R/W (rwpath=1) volume
244  *      "%[cell:]volume.readonly"       R/O volume
245  *      "#[cell:]volume.readonly"       R/O volume
246  *      "%[cell:]volume.backup"         Backup volume
247  *      "#[cell:]volume.backup"         Backup volume
248  */
249 static int afs_parse_device_name(struct afs_mount_params *params,
250                                  const char *name)
251 {
252         struct afs_cell *cell;
253         const char *cellname, *suffix;
254         int cellnamesz;
255 
256         _enter(",%s", name);
257 
258         if (!name) {
259                 printk(KERN_ERR "kAFS: no volume name specified\n");
260                 return -EINVAL;
261         }
262 
263         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
264                 printk(KERN_ERR "kAFS: unparsable volume name\n");
265                 return -EINVAL;
266         }
267 
268         /* determine the type of volume we're looking for */
269         params->type = AFSVL_ROVOL;
270         params->force = false;
271         if (params->rwpath || name[0] == '%') {
272                 params->type = AFSVL_RWVOL;
273                 params->force = true;
274         }
275         name++;
276 
277         /* split the cell name out if there is one */
278         params->volname = strchr(name, ':');
279         if (params->volname) {
280                 cellname = name;
281                 cellnamesz = params->volname - name;
282                 params->volname++;
283         } else {
284                 params->volname = name;
285                 cellname = NULL;
286                 cellnamesz = 0;
287         }
288 
289         /* the volume type is further affected by a possible suffix */
290         suffix = strrchr(params->volname, '.');
291         if (suffix) {
292                 if (strcmp(suffix, ".readonly") == 0) {
293                         params->type = AFSVL_ROVOL;
294                         params->force = true;
295                 } else if (strcmp(suffix, ".backup") == 0) {
296                         params->type = AFSVL_BACKVOL;
297                         params->force = true;
298                 } else if (suffix[1] == 0) {
299                 } else {
300                         suffix = NULL;
301                 }
302         }
303 
304         params->volnamesz = suffix ?
305                 suffix - params->volname : strlen(params->volname);
306 
307         _debug("cell %*.*s [%p]",
308                cellnamesz, cellnamesz, cellname ?: "", params->cell);
309 
310         /* lookup the cell record */
311         if (cellname || !params->cell) {
312                 cell = afs_lookup_cell(params->net, cellname, cellnamesz,
313                                        NULL, false);
314                 if (IS_ERR(cell)) {
315                         printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
316                                cellnamesz, cellnamesz, cellname ?: "");
317                         return PTR_ERR(cell);
318                 }
319                 afs_put_cell(params->net, params->cell);
320                 params->cell = cell;
321         }
322 
323         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
324                params->cell->name, params->cell,
325                params->volnamesz, params->volnamesz, params->volname,
326                suffix ?: "-", params->type, params->force ? " FORCE" : "");
327 
328         return 0;
329 }
330 
331 /*
332  * check a superblock to see if it's the one we're looking for
333  */
334 static int afs_test_super(struct super_block *sb, void *data)
335 {
336         struct afs_super_info *as1 = data;
337         struct afs_super_info *as = AFS_FS_S(sb);
338 
339         return as->net == as1->net && as->volume->vid == as1->volume->vid;
340 }
341 
342 static int afs_set_super(struct super_block *sb, void *data)
343 {
344         struct afs_super_info *as = data;
345 
346         sb->s_fs_info = as;
347         return set_anon_super(sb, NULL);
348 }
349 
350 /*
351  * fill in the superblock
352  */
353 static int afs_fill_super(struct super_block *sb,
354                           struct afs_mount_params *params)
355 {
356         struct afs_super_info *as = AFS_FS_S(sb);
357         struct afs_fid fid;
358         struct inode *inode = NULL;
359         int ret;
360 
361         _enter("");
362 
363         /* fill in the superblock */
364         sb->s_blocksize         = PAGE_SIZE;
365         sb->s_blocksize_bits    = PAGE_SHIFT;
366         sb->s_magic             = AFS_FS_MAGIC;
367         sb->s_op                = &afs_super_ops;
368         sb->s_xattr             = afs_xattr_handlers;
369         ret = super_setup_bdi(sb);
370         if (ret)
371                 return ret;
372         sb->s_bdi->ra_pages     = VM_MAX_READAHEAD * 1024 / PAGE_SIZE;
373         sprintf(sb->s_id, "%u", as->volume->vid);
374 
375         afs_activate_volume(as->volume);
376 
377         /* allocate the root inode and dentry */
378         fid.vid         = as->volume->vid;
379         fid.vnode       = 1;
380         fid.unique      = 1;
381         inode = afs_iget(sb, params->key, &fid, NULL, NULL, NULL);
382         if (IS_ERR(inode))
383                 return PTR_ERR(inode);
384 
385         if (params->autocell)
386                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
387 
388         ret = -ENOMEM;
389         sb->s_root = d_make_root(inode);
390         if (!sb->s_root)
391                 goto error;
392 
393         sb->s_d_op = &afs_fs_dentry_operations;
394 
395         _leave(" = 0");
396         return 0;
397 
398 error:
399         _leave(" = %d", ret);
400         return ret;
401 }
402 
403 static struct afs_super_info *afs_alloc_sbi(struct afs_mount_params *params)
404 {
405         struct afs_super_info *as;
406 
407         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
408         if (as) {
409                 as->net = afs_get_net(params->net);
410                 as->cell = afs_get_cell(params->cell);
411         }
412         return as;
413 }
414 
415 static void afs_destroy_sbi(struct afs_super_info *as)
416 {
417         if (as) {
418                 afs_put_volume(as->cell, as->volume);
419                 afs_put_cell(as->net, as->cell);
420                 afs_put_net(as->net);
421                 kfree(as);
422         }
423 }
424 
425 /*
426  * get an AFS superblock
427  */
428 static struct dentry *afs_mount(struct file_system_type *fs_type,
429                                 int flags, const char *dev_name, void *options)
430 {
431         struct afs_mount_params params;
432         struct super_block *sb;
433         struct afs_volume *candidate;
434         struct key *key;
435         struct afs_super_info *as;
436         int ret;
437 
438         _enter(",,%s,%p", dev_name, options);
439 
440         memset(&params, 0, sizeof(params));
441         params.net = &__afs_net;
442 
443         ret = -EINVAL;
444         if (current->nsproxy->net_ns != &init_net)
445                 goto error;
446 
447         /* parse the options and device name */
448         if (options) {
449                 ret = afs_parse_options(&params, options, &dev_name);
450                 if (ret < 0)
451                         goto error;
452         }
453 
454         ret = afs_parse_device_name(&params, dev_name);
455         if (ret < 0)
456                 goto error;
457 
458         /* try and do the mount securely */
459         key = afs_request_key(params.cell);
460         if (IS_ERR(key)) {
461                 _leave(" = %ld [key]", PTR_ERR(key));
462                 ret = PTR_ERR(key);
463                 goto error;
464         }
465         params.key = key;
466 
467         /* allocate a superblock info record */
468         ret = -ENOMEM;
469         as = afs_alloc_sbi(&params);
470         if (!as)
471                 goto error_key;
472 
473         /* Assume we're going to need a volume record; at the very least we can
474          * use it to update the volume record if we have one already.  This
475          * checks that the volume exists within the cell.
476          */
477         candidate = afs_create_volume(&params);
478         if (IS_ERR(candidate)) {
479                 ret = PTR_ERR(candidate);
480                 goto error_as;
481         }
482 
483         as->volume = candidate;
484 
485         /* allocate a deviceless superblock */
486         sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
487         if (IS_ERR(sb)) {
488                 ret = PTR_ERR(sb);
489                 goto error_as;
490         }
491 
492         if (!sb->s_root) {
493                 /* initial superblock/root creation */
494                 _debug("create");
495                 ret = afs_fill_super(sb, &params);
496                 if (ret < 0)
497                         goto error_sb;
498                 as = NULL;
499                 sb->s_flags |= SB_ACTIVE;
500         } else {
501                 _debug("reuse");
502                 ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
503                 afs_destroy_sbi(as);
504                 as = NULL;
505         }
506 
507         afs_put_cell(params.net, params.cell);
508         key_put(params.key);
509         _leave(" = 0 [%p]", sb);
510         return dget(sb->s_root);
511 
512 error_sb:
513         deactivate_locked_super(sb);
514         goto error_key;
515 error_as:
516         afs_destroy_sbi(as);
517 error_key:
518         key_put(params.key);
519 error:
520         afs_put_cell(params.net, params.cell);
521         _leave(" = %d", ret);
522         return ERR_PTR(ret);
523 }
524 
525 static void afs_kill_super(struct super_block *sb)
526 {
527         struct afs_super_info *as = AFS_FS_S(sb);
528 
529         /* Clear the callback interests (which will do ilookup5) before
530          * deactivating the superblock.
531          */
532         afs_clear_callback_interests(as->net, as->volume->servers);
533         kill_anon_super(sb);
534         afs_deactivate_volume(as->volume);
535         afs_destroy_sbi(as);
536 }
537 
538 /*
539  * Initialise an inode cache slab element prior to any use.  Note that
540  * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
541  * inode to another.
542  */
543 static void afs_i_init_once(void *_vnode)
544 {
545         struct afs_vnode *vnode = _vnode;
546 
547         memset(vnode, 0, sizeof(*vnode));
548         inode_init_once(&vnode->vfs_inode);
549         mutex_init(&vnode->io_lock);
550         mutex_init(&vnode->validate_lock);
551         spin_lock_init(&vnode->wb_lock);
552         spin_lock_init(&vnode->lock);
553         INIT_LIST_HEAD(&vnode->wb_keys);
554         INIT_LIST_HEAD(&vnode->pending_locks);
555         INIT_LIST_HEAD(&vnode->granted_locks);
556         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
557         seqlock_init(&vnode->cb_lock);
558 }
559 
560 /*
561  * allocate an AFS inode struct from our slab cache
562  */
563 static struct inode *afs_alloc_inode(struct super_block *sb)
564 {
565         struct afs_vnode *vnode;
566 
567         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
568         if (!vnode)
569                 return NULL;
570 
571         atomic_inc(&afs_count_active_inodes);
572 
573         /* Reset anything that shouldn't leak from one inode to the next. */
574         memset(&vnode->fid, 0, sizeof(vnode->fid));
575         memset(&vnode->status, 0, sizeof(vnode->status));
576 
577         vnode->volume           = NULL;
578         vnode->lock_key         = NULL;
579         vnode->permit_cache     = NULL;
580         vnode->cb_interest      = NULL;
581 #ifdef CONFIG_AFS_FSCACHE
582         vnode->cache            = NULL;
583 #endif
584 
585         vnode->flags            = 1 << AFS_VNODE_UNSET;
586         vnode->cb_type          = 0;
587         vnode->lock_state       = AFS_VNODE_LOCK_NONE;
588 
589         _leave(" = %p", &vnode->vfs_inode);
590         return &vnode->vfs_inode;
591 }
592 
593 static void afs_i_callback(struct rcu_head *head)
594 {
595         struct inode *inode = container_of(head, struct inode, i_rcu);
596         struct afs_vnode *vnode = AFS_FS_I(inode);
597         kmem_cache_free(afs_inode_cachep, vnode);
598 }
599 
600 /*
601  * destroy an AFS inode struct
602  */
603 static void afs_destroy_inode(struct inode *inode)
604 {
605         struct afs_vnode *vnode = AFS_FS_I(inode);
606 
607         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
608 
609         _debug("DESTROY INODE %p", inode);
610 
611         ASSERTCMP(vnode->cb_interest, ==, NULL);
612 
613         call_rcu(&inode->i_rcu, afs_i_callback);
614         atomic_dec(&afs_count_active_inodes);
615 }
616 
617 /*
618  * return information about an AFS volume
619  */
620 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
621 {
622         struct afs_fs_cursor fc;
623         struct afs_volume_status vs;
624         struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
625         struct key *key;
626         int ret;
627 
628         key = afs_request_key(vnode->volume->cell);
629         if (IS_ERR(key))
630                 return PTR_ERR(key);
631 
632         ret = -ERESTARTSYS;
633         if (afs_begin_vnode_operation(&fc, vnode, key)) {
634                 fc.flags |= AFS_FS_CURSOR_NO_VSLEEP;
635                 while (afs_select_fileserver(&fc)) {
636                         fc.cb_break = vnode->cb_break + vnode->cb_s_break;
637                         afs_fs_get_volume_status(&fc, &vs);
638                 }
639 
640                 afs_check_for_remote_deletion(&fc, fc.vnode);
641                 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
642                 ret = afs_end_vnode_operation(&fc);
643         }
644 
645         key_put(key);
646 
647         if (ret == 0) {
648                 buf->f_type     = dentry->d_sb->s_magic;
649                 buf->f_bsize    = AFS_BLOCK_SIZE;
650                 buf->f_namelen  = AFSNAMEMAX - 1;
651 
652                 if (vs.max_quota == 0)
653                         buf->f_blocks = vs.part_max_blocks;
654                 else
655                         buf->f_blocks = vs.max_quota;
656                 buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
657         }
658 
659         return ret;
660 }
661 

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