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@redhat.com>
  14  *
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <linux/fs.h>
  22 #include <linux/pagemap.h>
  23 #include "internal.h"
  24
  25 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  26
  27 struct afs_mount_params {
  28         int                     rwpath;
  29         struct afs_cell         *default_cell;
  30         struct afs_volume       *volume;
  31 };
  32
  33 static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
  34                             unsigned long flags);
  35
  36 static int afs_get_sb(struct file_system_type *fs_type,
  37                       int flags, const char *dev_name,
  38                       void *data, struct vfsmount *mnt);
  39
  40 static struct inode *afs_alloc_inode(struct super_block *sb);
  41
  42 static void afs_put_super(struct super_block *sb);
  43
  44 static void afs_destroy_inode(struct inode *inode);
  45
  46 struct file_system_type afs_fs_type = {
  47         .owner          = THIS_MODULE,
  48         .name           = "afs",
  49         .get_sb         = afs_get_sb,
  50         .kill_sb        = kill_anon_super,
  51         .fs_flags       = FS_BINARY_MOUNTDATA,
  52 };
  53
  54 static const struct super_operations afs_super_ops = {
  55         .statfs         = simple_statfs,
  56         .alloc_inode    = afs_alloc_inode,
  57         .drop_inode     = generic_delete_inode,
  58         .destroy_inode  = afs_destroy_inode,
  59         .clear_inode    = afs_clear_inode,
  60         .umount_begin   = afs_umount_begin,
  61         .put_super      = afs_put_super,
  62 };
  63
  64 static struct kmem_cache *afs_inode_cachep;
  65 static atomic_t afs_count_active_inodes;
  66
  67 /*
  68  * initialise the filesystem
  69  */
  70 int __init afs_fs_init(void)
  71 {
  72         int ret;
  73
  74         _enter("");
  75
  76         /* create ourselves an inode cache */
  77         atomic_set(&afs_count_active_inodes, 0);
  78
  79         ret = -ENOMEM;
  80         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  81                                              sizeof(struct afs_vnode),
  82                                              0,
  83                                              SLAB_HWCACHE_ALIGN,
  84                                              afs_i_init_once,
  85                                              NULL);
  86         if (!afs_inode_cachep) {
  87                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
  88                 return ret;
  89         }
  90
  91         /* now export our filesystem to lesser mortals */
  92         ret = register_filesystem(&afs_fs_type);
  93         if (ret < 0) {
  94                 kmem_cache_destroy(afs_inode_cachep);
  95                 _leave(" = %d", ret);
  96                 return ret;
  97         }
  98
  99         _leave(" = 0");
 100         return 0;
 101 }
 102
 103 /*
 104  * clean up the filesystem
 105  */
 106 void __exit afs_fs_exit(void)
 107 {
 108         _enter("");
 109
 110         afs_mntpt_kill_timer();
 111         unregister_filesystem(&afs_fs_type);
 112
 113         if (atomic_read(&afs_count_active_inodes) != 0) {
 114                 printk("kAFS: %d active inode objects still present\n",
 115                        atomic_read(&afs_count_active_inodes));
 116                 BUG();
 117         }
 118
 119         kmem_cache_destroy(afs_inode_cachep);
 120         _leave("");
 121 }
 122
 123 /*
 124  * check that an argument has a value
 125  */
 126 static int want_arg(char **_value, const char *option)
 127 {
 128         if (!_value || !*_value || !**_value) {
 129                 printk(KERN_NOTICE "kAFS: %s: argument missing\n", option);
 130                 return 0;
 131         }
 132         return 1;
 133 }
 134
 135 /*
 136  * check that there's no subsequent value
 137  */
 138 static int want_no_value(char *const *_value, const char *option)
 139 {
 140         if (*_value && **_value) {
 141                 printk(KERN_NOTICE "kAFS: %s: Invalid argument: %s\n",
 142                        option, *_value);
 143                 return 0;
 144         }
 145         return 1;
 146 }
 147
 148 /*
 149  * parse the mount options
 150  * - this function has been shamelessly adapted from the ext3 fs which
 151  *   shamelessly adapted it from the msdos fs
 152  */
 153 static int afs_super_parse_options(struct afs_mount_params *params,
 154                                    char *options, const char **devname)
 155 {
 156         struct afs_cell *cell;
 157         char *key, *value;
 158         int ret;
 159
 160         _enter("%s", options);
 161
 162         options[PAGE_SIZE - 1] = 0;
 163
 164         ret = 0;
 165         while ((key = strsep(&options, ","))) {
 166                 value = strchr(key, '=');
 167                 if (value)
 168                         *value++ = 0;
 169
 170                 _debug("kAFS: KEY: %s, VAL:%s", key, value ?: "-");
 171
 172                 if (strcmp(key, "rwpath") == 0) {
 173                         if (!want_no_value(&value, "rwpath"))
 174                                 return -EINVAL;
 175                         params->rwpath = 1;
 176                 } else if (strcmp(key, "vol") == 0) {
 177                         if (!want_arg(&value, "vol"))
 178                                 return -EINVAL;
 179                         *devname = value;
 180                 } else if (strcmp(key, "cell") == 0) {
 181                         if (!want_arg(&value, "cell"))
 182                                 return -EINVAL;
 183                         cell = afs_cell_lookup(value, strlen(value));
 184                         if (IS_ERR(cell))
 185                                 return PTR_ERR(cell);
 186                         afs_put_cell(params->default_cell);
 187                         params->default_cell = cell;
 188                 } else {
 189                         printk("kAFS: Unknown mount option: '%s'\n",  key);
 190                         ret = -EINVAL;
 191                         goto error;
 192                 }
 193         }
 194
 195         ret = 0;
 196 error:
 197         _leave(" = %d", ret);
 198         return ret;
 199 }
 200
 201 /*
 202  * check a superblock to see if it's the one we're looking for
 203  */
 204 static int afs_test_super(struct super_block *sb, void *data)
 205 {
 206         struct afs_mount_params *params = data;
 207         struct afs_super_info *as = sb->s_fs_info;
 208
 209         return as->volume == params->volume;
 210 }
 211
 212 /*
 213  * fill in the superblock
 214  */
 215 static int afs_fill_super(struct super_block *sb, void *data)
 216 {
 217         struct afs_mount_params *params = data;
 218         struct afs_super_info *as = NULL;
 219         struct afs_fid fid;
 220         struct dentry *root = NULL;
 221         struct inode *inode = NULL;
 222         int ret;
 223
 224         _enter("");
 225
 226         /* allocate a superblock info record */
 227         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 228         if (!as) {
 229                 _leave(" = -ENOMEM");
 230                 return -ENOMEM;
 231         }
 232
 233         afs_get_volume(params->volume);
 234         as->volume = params->volume;
 235
 236         /* fill in the superblock */
 237         sb->s_blocksize         = PAGE_CACHE_SIZE;
 238         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 239         sb->s_magic             = AFS_FS_MAGIC;
 240         sb->s_op                = &afs_super_ops;
 241         sb->s_fs_info           = as;
 242
 243         /* allocate the root inode and dentry */
 244         fid.vid         = as->volume->vid;
 245         fid.vnode       = 1;
 246         fid.unique      = 1;
 247         inode = afs_iget(sb, &fid);
 248         if (IS_ERR(inode))
 249                 goto error_inode;
 250
 251         ret = -ENOMEM;
 252         root = d_alloc_root(inode);
 253         if (!root)
 254                 goto error;
 255
 256         sb->s_root = root;
 257
 258         _leave(" = 0");
 259         return 0;
 260
 261 error_inode:
 262         ret = PTR_ERR(inode);
 263         inode = NULL;
 264 error:
 265         iput(inode);
 266         afs_put_volume(as->volume);
 267         kfree(as);
 268
 269         sb->s_fs_info = NULL;
 270
 271         _leave(" = %d", ret);
 272         return ret;
 273 }
 274
 275 /*
 276  * get an AFS superblock
 277  * - TODO: don't use get_sb_nodev(), but rather call sget() directly
 278  */
 279 static int afs_get_sb(struct file_system_type *fs_type,
 280                       int flags,
 281                       const char *dev_name,
 282                       void *options,
 283                       struct vfsmount *mnt)
 284 {
 285         struct afs_mount_params params;
 286         struct super_block *sb;
 287         struct afs_volume *vol;
 288         int ret;
 289
 290         _enter(",,%s,%p", dev_name, options);
 291
 292         memset(&params, 0, sizeof(params));
 293
 294         /* parse the options */
 295         if (options) {
 296                 ret = afs_super_parse_options(&params, options, &dev_name);
 297                 if (ret < 0)
 298                         goto error;
 299                 if (!dev_name) {
 300                         printk("kAFS: no volume name specified\n");
 301                         ret = -EINVAL;
 302                         goto error;
 303                 }
 304         }
 305
 306         /* parse the device name */
 307         vol = afs_volume_lookup(dev_name, params.default_cell, params.rwpath);
 308         if (IS_ERR(vol)) {
 309                 ret = PTR_ERR(vol);
 310                 goto error;
 311         }
 312
 313         params.volume = vol;
 314
 315         /* allocate a deviceless superblock */
 316         sb = sget(fs_type, afs_test_super, set_anon_super, &params);
 317         if (IS_ERR(sb)) {
 318                 ret = PTR_ERR(sb);
 319                 goto error;
 320         }
 321
 322         if (!sb->s_root) {
 323                 /* initial superblock/root creation */
 324                 _debug("create");
 325                 sb->s_flags = flags;
 326                 ret = afs_fill_super(sb, &params);
 327                 if (ret < 0) {
 328                         up_write(&sb->s_umount);
 329                         deactivate_super(sb);
 330                         goto error;
 331                 }
 332                 sb->s_flags |= MS_ACTIVE;
 333         } else {
 334                 _debug("reuse");
 335                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 336         }
 337
 338         simple_set_mnt(mnt, sb);
 339         afs_put_volume(params.volume);
 340         afs_put_cell(params.default_cell);
 341         _leave(" = 0 [%p]", sb);
 342         return 0;
 343
 344 error:
 345         afs_put_volume(params.volume);
 346         afs_put_cell(params.default_cell);
 347         _leave(" = %d", ret);
 348         return ret;
 349 }
 350
 351 /*
 352  * finish the unmounting process on the superblock
 353  */
 354 static void afs_put_super(struct super_block *sb)
 355 {
 356         struct afs_super_info *as = sb->s_fs_info;
 357
 358         _enter("");
 359
 360         afs_put_volume(as->volume);
 361
 362         _leave("");
 363 }
 364
 365 /*
 366  * initialise an inode cache slab element prior to any use
 367  */
 368 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
 369                             unsigned long flags)
 370 {
 371         struct afs_vnode *vnode = _vnode;
 372
 373         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 374             SLAB_CTOR_CONSTRUCTOR) {
 375                 memset(vnode, 0, sizeof(*vnode));
 376                 inode_init_once(&vnode->vfs_inode);
 377                 init_waitqueue_head(&vnode->update_waitq);
 378                 spin_lock_init(&vnode->lock);
 379                 INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 380                 mutex_init(&vnode->cb_broken_lock);
 381         }
 382 }
 383
 384 /*
 385  * allocate an AFS inode struct from our slab cache
 386  */
 387 static struct inode *afs_alloc_inode(struct super_block *sb)
 388 {
 389         struct afs_vnode *vnode;
 390
 391         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 392         if (!vnode)
 393                 return NULL;
 394
 395         atomic_inc(&afs_count_active_inodes);
 396
 397         memset(&vnode->fid, 0, sizeof(vnode->fid));
 398         memset(&vnode->status, 0, sizeof(vnode->status));
 399
 400         vnode->volume           = NULL;
 401         vnode->update_cnt       = 0;
 402         vnode->flags            = 0;
 403         vnode->cb_promised      = false;
 404
 405         return &vnode->vfs_inode;
 406 }
 407
 408 /*
 409  * destroy an AFS inode struct
 410  */
 411 static void afs_destroy_inode(struct inode *inode)
 412 {
 413         struct afs_vnode *vnode = AFS_FS_I(inode);
 414
 415         _enter("{%lu}", inode->i_ino);
 416
 417         _debug("DESTROY INODE %p", inode);
 418
 419         ASSERTCMP(vnode->server, ==, NULL);
 420
 421         kmem_cache_free(afs_inode_cachep, vnode);
 422         atomic_dec(&afs_count_active_inodes);
 423 }