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Linux/fs/afs/super.c

  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 <net/net_namespace.h>
 29 #include "internal.h"
 30 
 31 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
 32 
 33 static void afs_i_init_once(void *foo);
 34 static struct dentry *afs_mount(struct file_system_type *fs_type,
 35                       int flags, const char *dev_name, void *data);
 36 static void afs_kill_super(struct super_block *sb);
 37 static struct inode *afs_alloc_inode(struct super_block *sb);
 38 static void afs_destroy_inode(struct inode *inode);
 39 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
 40 
 41 struct file_system_type afs_fs_type = {
 42         .owner          = THIS_MODULE,
 43         .name           = "afs",
 44         .mount          = afs_mount,
 45         .kill_sb        = afs_kill_super,
 46         .fs_flags       = 0,
 47 };
 48 MODULE_ALIAS_FS("afs");
 49 
 50 static const struct super_operations afs_super_ops = {
 51         .statfs         = afs_statfs,
 52         .alloc_inode    = afs_alloc_inode,
 53         .drop_inode     = afs_drop_inode,
 54         .destroy_inode  = afs_destroy_inode,
 55         .evict_inode    = afs_evict_inode,
 56         .show_options   = generic_show_options,
 57 };
 58 
 59 static struct kmem_cache *afs_inode_cachep;
 60 static atomic_t afs_count_active_inodes;
 61 
 62 enum {
 63         afs_no_opt,
 64         afs_opt_cell,
 65         afs_opt_rwpath,
 66         afs_opt_vol,
 67         afs_opt_autocell,
 68 };
 69 
 70 static const match_table_t afs_options_list = {
 71         { afs_opt_cell,         "cell=%s"       },
 72         { afs_opt_rwpath,       "rwpath"        },
 73         { afs_opt_vol,          "vol=%s"        },
 74         { afs_opt_autocell,     "autocell"      },
 75         { afs_no_opt,           NULL            },
 76 };
 77 
 78 /*
 79  * initialise the filesystem
 80  */
 81 int __init afs_fs_init(void)
 82 {
 83         int ret;
 84 
 85         _enter("");
 86 
 87         /* create ourselves an inode cache */
 88         atomic_set(&afs_count_active_inodes, 0);
 89 
 90         ret = -ENOMEM;
 91         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
 92                                              sizeof(struct afs_vnode),
 93                                              0,
 94                                              SLAB_HWCACHE_ALIGN,
 95                                              afs_i_init_once);
 96         if (!afs_inode_cachep) {
 97                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
 98                 return ret;
 99         }
100 
101         /* now export our filesystem to lesser mortals */
102         ret = register_filesystem(&afs_fs_type);
103         if (ret < 0) {
104                 kmem_cache_destroy(afs_inode_cachep);
105                 _leave(" = %d", ret);
106                 return ret;
107         }
108 
109         _leave(" = 0");
110         return 0;
111 }
112 
113 /*
114  * clean up the filesystem
115  */
116 void __exit afs_fs_exit(void)
117 {
118         _enter("");
119 
120         afs_mntpt_kill_timer();
121         unregister_filesystem(&afs_fs_type);
122 
123         if (atomic_read(&afs_count_active_inodes) != 0) {
124                 printk("kAFS: %d active inode objects still present\n",
125                        atomic_read(&afs_count_active_inodes));
126                 BUG();
127         }
128 
129         /*
130          * Make sure all delayed rcu free inodes are flushed before we
131          * destroy cache.
132          */
133         rcu_barrier();
134         kmem_cache_destroy(afs_inode_cachep);
135         _leave("");
136 }
137 
138 /*
139  * parse the mount options
140  * - this function has been shamelessly adapted from the ext3 fs which
141  *   shamelessly adapted it from the msdos fs
142  */
143 static int afs_parse_options(struct afs_mount_params *params,
144                              char *options, const char **devname)
145 {
146         struct afs_cell *cell;
147         substring_t args[MAX_OPT_ARGS];
148         char *p;
149         int token;
150 
151         _enter("%s", options);
152 
153         options[PAGE_SIZE - 1] = 0;
154 
155         while ((p = strsep(&options, ","))) {
156                 if (!*p)
157                         continue;
158 
159                 token = match_token(p, afs_options_list, args);
160                 switch (token) {
161                 case afs_opt_cell:
162                         cell = afs_cell_lookup(args[0].from,
163                                                args[0].to - args[0].from,
164                                                false);
165                         if (IS_ERR(cell))
166                                 return PTR_ERR(cell);
167                         afs_put_cell(params->cell);
168                         params->cell = cell;
169                         break;
170 
171                 case afs_opt_rwpath:
172                         params->rwpath = 1;
173                         break;
174 
175                 case afs_opt_vol:
176                         *devname = args[0].from;
177                         break;
178 
179                 case afs_opt_autocell:
180                         params->autocell = 1;
181                         break;
182 
183                 default:
184                         printk(KERN_ERR "kAFS:"
185                                " Unknown or invalid mount option: '%s'\n", p);
186                         return -EINVAL;
187                 }
188         }
189 
190         _leave(" = 0");
191         return 0;
192 }
193 
194 /*
195  * parse a device name to get cell name, volume name, volume type and R/W
196  * selector
197  * - this can be one of the following:
198  *      "%[cell:]volume[.]"             R/W volume
199  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
200  *                                       or R/W (rwpath=1) volume
201  *      "%[cell:]volume.readonly"       R/O volume
202  *      "#[cell:]volume.readonly"       R/O volume
203  *      "%[cell:]volume.backup"         Backup volume
204  *      "#[cell:]volume.backup"         Backup volume
205  */
206 static int afs_parse_device_name(struct afs_mount_params *params,
207                                  const char *name)
208 {
209         struct afs_cell *cell;
210         const char *cellname, *suffix;
211         int cellnamesz;
212 
213         _enter(",%s", name);
214 
215         if (!name) {
216                 printk(KERN_ERR "kAFS: no volume name specified\n");
217                 return -EINVAL;
218         }
219 
220         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
221                 printk(KERN_ERR "kAFS: unparsable volume name\n");
222                 return -EINVAL;
223         }
224 
225         /* determine the type of volume we're looking for */
226         params->type = AFSVL_ROVOL;
227         params->force = false;
228         if (params->rwpath || name[0] == '%') {
229                 params->type = AFSVL_RWVOL;
230                 params->force = true;
231         }
232         name++;
233 
234         /* split the cell name out if there is one */
235         params->volname = strchr(name, ':');
236         if (params->volname) {
237                 cellname = name;
238                 cellnamesz = params->volname - name;
239                 params->volname++;
240         } else {
241                 params->volname = name;
242                 cellname = NULL;
243                 cellnamesz = 0;
244         }
245 
246         /* the volume type is further affected by a possible suffix */
247         suffix = strrchr(params->volname, '.');
248         if (suffix) {
249                 if (strcmp(suffix, ".readonly") == 0) {
250                         params->type = AFSVL_ROVOL;
251                         params->force = true;
252                 } else if (strcmp(suffix, ".backup") == 0) {
253                         params->type = AFSVL_BACKVOL;
254                         params->force = true;
255                 } else if (suffix[1] == 0) {
256                 } else {
257                         suffix = NULL;
258                 }
259         }
260 
261         params->volnamesz = suffix ?
262                 suffix - params->volname : strlen(params->volname);
263 
264         _debug("cell %*.*s [%p]",
265                cellnamesz, cellnamesz, cellname ?: "", params->cell);
266 
267         /* lookup the cell record */
268         if (cellname || !params->cell) {
269                 cell = afs_cell_lookup(cellname, cellnamesz, true);
270                 if (IS_ERR(cell)) {
271                         printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
272                                cellnamesz, cellnamesz, cellname ?: "");
273                         return PTR_ERR(cell);
274                 }
275                 afs_put_cell(params->cell);
276                 params->cell = cell;
277         }
278 
279         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
280                params->cell->name, params->cell,
281                params->volnamesz, params->volnamesz, params->volname,
282                suffix ?: "-", params->type, params->force ? " FORCE" : "");
283 
284         return 0;
285 }
286 
287 /*
288  * check a superblock to see if it's the one we're looking for
289  */
290 static int afs_test_super(struct super_block *sb, void *data)
291 {
292         struct afs_super_info *as1 = data;
293         struct afs_super_info *as = sb->s_fs_info;
294 
295         return as->volume == as1->volume;
296 }
297 
298 static int afs_set_super(struct super_block *sb, void *data)
299 {
300         sb->s_fs_info = data;
301         return set_anon_super(sb, NULL);
302 }
303 
304 /*
305  * fill in the superblock
306  */
307 static int afs_fill_super(struct super_block *sb,
308                           struct afs_mount_params *params)
309 {
310         struct afs_super_info *as = sb->s_fs_info;
311         struct afs_fid fid;
312         struct inode *inode = NULL;
313         int ret;
314 
315         _enter("");
316 
317         /* fill in the superblock */
318         sb->s_blocksize         = PAGE_CACHE_SIZE;
319         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
320         sb->s_magic             = AFS_FS_MAGIC;
321         sb->s_op                = &afs_super_ops;
322         sb->s_bdi               = &as->volume->bdi;
323         strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
324 
325         /* allocate the root inode and dentry */
326         fid.vid         = as->volume->vid;
327         fid.vnode       = 1;
328         fid.unique      = 1;
329         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
330         if (IS_ERR(inode))
331                 return PTR_ERR(inode);
332 
333         if (params->autocell)
334                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
335 
336         ret = -ENOMEM;
337         sb->s_root = d_make_root(inode);
338         if (!sb->s_root)
339                 goto error;
340 
341         sb->s_d_op = &afs_fs_dentry_operations;
342 
343         _leave(" = 0");
344         return 0;
345 
346 error:
347         _leave(" = %d", ret);
348         return ret;
349 }
350 
351 /*
352  * get an AFS superblock
353  */
354 static struct dentry *afs_mount(struct file_system_type *fs_type,
355                       int flags, const char *dev_name, void *options)
356 {
357         struct afs_mount_params params;
358         struct super_block *sb;
359         struct afs_volume *vol;
360         struct key *key;
361         char *new_opts = kstrdup(options, GFP_KERNEL);
362         struct afs_super_info *as;
363         int ret;
364 
365         _enter(",,%s,%p", dev_name, options);
366 
367         memset(&params, 0, sizeof(params));
368 
369         ret = -EINVAL;
370         if (current->nsproxy->net_ns != &init_net)
371                 goto error;
372 
373         /* parse the options and device name */
374         if (options) {
375                 ret = afs_parse_options(&params, options, &dev_name);
376                 if (ret < 0)
377                         goto error;
378         }
379 
380         ret = afs_parse_device_name(&params, dev_name);
381         if (ret < 0)
382                 goto error;
383 
384         /* try and do the mount securely */
385         key = afs_request_key(params.cell);
386         if (IS_ERR(key)) {
387                 _leave(" = %ld [key]", PTR_ERR(key));
388                 ret = PTR_ERR(key);
389                 goto error;
390         }
391         params.key = key;
392 
393         /* parse the device name */
394         vol = afs_volume_lookup(&params);
395         if (IS_ERR(vol)) {
396                 ret = PTR_ERR(vol);
397                 goto error;
398         }
399 
400         /* allocate a superblock info record */
401         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
402         if (!as) {
403                 ret = -ENOMEM;
404                 afs_put_volume(vol);
405                 goto error;
406         }
407         as->volume = vol;
408 
409         /* allocate a deviceless superblock */
410         sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
411         if (IS_ERR(sb)) {
412                 ret = PTR_ERR(sb);
413                 afs_put_volume(vol);
414                 kfree(as);
415                 goto error;
416         }
417 
418         if (!sb->s_root) {
419                 /* initial superblock/root creation */
420                 _debug("create");
421                 ret = afs_fill_super(sb, &params);
422                 if (ret < 0) {
423                         deactivate_locked_super(sb);
424                         goto error;
425                 }
426                 save_mount_options(sb, new_opts);
427                 sb->s_flags |= MS_ACTIVE;
428         } else {
429                 _debug("reuse");
430                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
431                 afs_put_volume(vol);
432                 kfree(as);
433         }
434 
435         afs_put_cell(params.cell);
436         kfree(new_opts);
437         _leave(" = 0 [%p]", sb);
438         return dget(sb->s_root);
439 
440 error:
441         afs_put_cell(params.cell);
442         key_put(params.key);
443         kfree(new_opts);
444         _leave(" = %d", ret);
445         return ERR_PTR(ret);
446 }
447 
448 static void afs_kill_super(struct super_block *sb)
449 {
450         struct afs_super_info *as = sb->s_fs_info;
451         kill_anon_super(sb);
452         afs_put_volume(as->volume);
453         kfree(as);
454 }
455 
456 /*
457  * initialise an inode cache slab element prior to any use
458  */
459 static void afs_i_init_once(void *_vnode)
460 {
461         struct afs_vnode *vnode = _vnode;
462 
463         memset(vnode, 0, sizeof(*vnode));
464         inode_init_once(&vnode->vfs_inode);
465         init_waitqueue_head(&vnode->update_waitq);
466         mutex_init(&vnode->permits_lock);
467         mutex_init(&vnode->validate_lock);
468         spin_lock_init(&vnode->writeback_lock);
469         spin_lock_init(&vnode->lock);
470         INIT_LIST_HEAD(&vnode->writebacks);
471         INIT_LIST_HEAD(&vnode->pending_locks);
472         INIT_LIST_HEAD(&vnode->granted_locks);
473         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
474         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
475 }
476 
477 /*
478  * allocate an AFS inode struct from our slab cache
479  */
480 static struct inode *afs_alloc_inode(struct super_block *sb)
481 {
482         struct afs_vnode *vnode;
483 
484         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
485         if (!vnode)
486                 return NULL;
487 
488         atomic_inc(&afs_count_active_inodes);
489 
490         memset(&vnode->fid, 0, sizeof(vnode->fid));
491         memset(&vnode->status, 0, sizeof(vnode->status));
492 
493         vnode->volume           = NULL;
494         vnode->update_cnt       = 0;
495         vnode->flags            = 1 << AFS_VNODE_UNSET;
496         vnode->cb_promised      = false;
497 
498         _leave(" = %p", &vnode->vfs_inode);
499         return &vnode->vfs_inode;
500 }
501 
502 static void afs_i_callback(struct rcu_head *head)
503 {
504         struct inode *inode = container_of(head, struct inode, i_rcu);
505         struct afs_vnode *vnode = AFS_FS_I(inode);
506         kmem_cache_free(afs_inode_cachep, vnode);
507 }
508 
509 /*
510  * destroy an AFS inode struct
511  */
512 static void afs_destroy_inode(struct inode *inode)
513 {
514         struct afs_vnode *vnode = AFS_FS_I(inode);
515 
516         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
517 
518         _debug("DESTROY INODE %p", inode);
519 
520         ASSERTCMP(vnode->server, ==, NULL);
521 
522         call_rcu(&inode->i_rcu, afs_i_callback);
523         atomic_dec(&afs_count_active_inodes);
524 }
525 
526 /*
527  * return information about an AFS volume
528  */
529 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
530 {
531         struct afs_volume_status vs;
532         struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
533         struct key *key;
534         int ret;
535 
536         key = afs_request_key(vnode->volume->cell);
537         if (IS_ERR(key))
538                 return PTR_ERR(key);
539 
540         ret = afs_vnode_get_volume_status(vnode, key, &vs);
541         key_put(key);
542         if (ret < 0) {
543                 _leave(" = %d", ret);
544                 return ret;
545         }
546 
547         buf->f_type     = dentry->d_sb->s_magic;
548         buf->f_bsize    = AFS_BLOCK_SIZE;
549         buf->f_namelen  = AFSNAMEMAX - 1;
550 
551         if (vs.max_quota == 0)
552                 buf->f_blocks = vs.part_max_blocks;
553         else
554                 buf->f_blocks = vs.max_quota;
555         buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
556         return 0;
557 }
558 

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