fs/fuse/inode.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/pagemap.h>
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/mount.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/parser.h>
  20 #include <linux/statfs.h>
  21
  22 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
  23 MODULE_DESCRIPTION("Filesystem in Userspace");
  24 MODULE_LICENSE("GPL");
  25
  26 spinlock_t fuse_lock;
  27 static kmem_cache_t *fuse_inode_cachep;
  28 static int mount_count;
  29
  30 static int mount_max = 1000;
  31 module_param(mount_max, int, 0644);
  32 MODULE_PARM_DESC(mount_max, "Maximum number of FUSE mounts allowed, if -1 then unlimited (default: 1000)");
  33
  34 #define FUSE_SUPER_MAGIC 0x65735546
  35
  36 struct fuse_mount_data {
  37         int fd;
  38         unsigned rootmode;
  39         unsigned user_id;
  40 };
  41
  42 static struct inode *fuse_alloc_inode(struct super_block *sb)
  43 {
  44         struct inode *inode;
  45         struct fuse_inode *fi;
  46
  47         inode = kmem_cache_alloc(fuse_inode_cachep, SLAB_KERNEL);
  48         if (!inode)
  49                 return NULL;
  50
  51         fi = get_fuse_inode(inode);
  52         fi->i_time = jiffies - 1;
  53         fi->nodeid = 0;
  54
  55         return inode;
  56 }
  57
  58 static void fuse_destroy_inode(struct inode *inode)
  59 {
  60         kmem_cache_free(fuse_inode_cachep, inode);
  61 }
  62
  63 static void fuse_read_inode(struct inode *inode)
  64 {
  65         /* No op */
  66 }
  67
  68 static void fuse_clear_inode(struct inode *inode)
  69 {
  70 }
  71
  72 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
  73 {
  74         if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
  75                 invalidate_inode_pages(inode->i_mapping);
  76
  77         inode->i_ino     = attr->ino;
  78         inode->i_mode    = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
  79         inode->i_nlink   = attr->nlink;
  80         inode->i_uid     = attr->uid;
  81         inode->i_gid     = attr->gid;
  82         i_size_write(inode, attr->size);
  83         inode->i_blksize = PAGE_CACHE_SIZE;
  84         inode->i_blocks  = attr->blocks;
  85         inode->i_atime.tv_sec   = attr->atime;
  86         inode->i_atime.tv_nsec  = attr->atimensec;
  87         inode->i_mtime.tv_sec   = attr->mtime;
  88         inode->i_mtime.tv_nsec  = attr->mtimensec;
  89         inode->i_ctime.tv_sec   = attr->ctime;
  90         inode->i_ctime.tv_nsec  = attr->ctimensec;
  91 }
  92
  93 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
  94 {
  95         inode->i_mode = attr->mode & S_IFMT;
  96         i_size_write(inode, attr->size);
  97 }
  98
  99 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 100 {
 101         unsigned long nodeid = *(unsigned long *) _nodeidp;
 102         if (get_node_id(inode) == nodeid)
 103                 return 1;
 104         else
 105                 return 0;
 106 }
 107
 108 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 109 {
 110         unsigned long nodeid = *(unsigned long *) _nodeidp;
 111         get_fuse_inode(inode)->nodeid = nodeid;
 112         return 0;
 113 }
 114
 115 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 116                         int generation, struct fuse_attr *attr, int version)
 117 {
 118         struct inode *inode;
 119         struct fuse_conn *fc = get_fuse_conn_super(sb);
 120         int retried = 0;
 121
 122  retry:
 123         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 124         if (!inode)
 125                 return NULL;
 126
 127         if ((inode->i_state & I_NEW)) {
 128                 inode->i_generation = generation;
 129                 inode->i_data.backing_dev_info = &fc->bdi;
 130                 fuse_init_inode(inode, attr);
 131                 unlock_new_inode(inode);
 132         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 133                 BUG_ON(retried);
 134                 /* Inode has changed type, any I/O on the old should fail */
 135                 make_bad_inode(inode);
 136                 iput(inode);
 137                 retried = 1;
 138                 goto retry;
 139         }
 140
 141         fuse_change_attributes(inode, attr);
 142         inode->i_version = version;
 143         return inode;
 144 }
 145
 146 static void fuse_put_super(struct super_block *sb)
 147 {
 148         struct fuse_conn *fc = get_fuse_conn_super(sb);
 149
 150         spin_lock(&fuse_lock);
 151         mount_count --;
 152         fc->sb = NULL;
 153         fc->user_id = 0;
 154         fuse_release_conn(fc);
 155         *get_fuse_conn_super_p(sb) = NULL;
 156         spin_unlock(&fuse_lock);
 157 }
 158
 159 enum {
 160         OPT_FD,
 161         OPT_ROOTMODE,
 162         OPT_USER_ID,
 163         OPT_DEFAULT_PERMISSIONS,
 164         OPT_ALLOW_OTHER,
 165         OPT_ALLOW_ROOT,
 166         OPT_KERNEL_CACHE,
 167         OPT_ERR
 168 };
 169
 170 static match_table_t tokens = {
 171         {OPT_FD,                        "fd=%u"},
 172         {OPT_ROOTMODE,                  "rootmode=%o"},
 173         {OPT_USER_ID,                   "user_id=%u"},
 174         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 175         {OPT_ALLOW_OTHER,               "allow_other"},
 176         {OPT_ALLOW_ROOT,                "allow_root"},
 177         {OPT_KERNEL_CACHE,              "kernel_cache"},
 178         {OPT_ERR,                       NULL}
 179 };
 180
 181 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
 182 {
 183         char *p;
 184         memset(d, 0, sizeof(struct fuse_mount_data));
 185         d->fd = -1;
 186
 187         while ((p = strsep(&opt, ",")) != NULL) {
 188                 int token;
 189                 int value;
 190                 substring_t args[MAX_OPT_ARGS];
 191                 if (!*p)
 192                         continue;
 193
 194                 token = match_token(p, tokens, args);
 195                 switch (token) {
 196                 case OPT_FD:
 197                         if (match_int(&args[0], &value))
 198                                 return 0;
 199                         d->fd = value;
 200                         break;
 201
 202                 case OPT_ROOTMODE:
 203                         if (match_octal(&args[0], &value))
 204                                 return 0;
 205                         d->rootmode = value;
 206                         break;
 207
 208                 case OPT_USER_ID:
 209                         if (match_int(&args[0], &value))
 210                                 return 0;
 211                         d->user_id = value;
 212                         break;
 213
 214                 default:
 215                         return 0;
 216                 }
 217         }
 218         if (d->fd == -1)
 219                 return 0;
 220
 221         return 1;
 222 }
 223
 224 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
 225 {
 226         struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
 227
 228         seq_printf(m, ",user_id=%u", fc->user_id);
 229         return 0;
 230 }
 231
 232 void fuse_release_conn(struct fuse_conn *fc)
 233 {
 234         kfree(fc);
 235 }
 236
 237 static struct fuse_conn *new_conn(void)
 238 {
 239         struct fuse_conn *fc;
 240
 241         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
 242         if (fc != NULL) {
 243                 memset(fc, 0, sizeof(*fc));
 244                 fc->sb = NULL;
 245                 fc->user_id = 0;
 246                 fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 247                 fc->bdi.unplug_io_fn = default_unplug_io_fn;
 248         }
 249         return fc;
 250 }
 251
 252 static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
 253 {
 254         struct fuse_conn *fc;
 255
 256         fc = new_conn();
 257         if (fc == NULL)
 258                 return NULL;
 259         spin_lock(&fuse_lock);
 260         fc->sb = sb;
 261         spin_unlock(&fuse_lock);
 262         return fc;
 263 }
 264
 265 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
 266 {
 267         struct fuse_attr attr;
 268         memset(&attr, 0, sizeof(attr));
 269
 270         attr.mode = mode;
 271         attr.ino = FUSE_ROOT_ID;
 272         return fuse_iget(sb, 1, 0, &attr, 0);
 273 }
 274
 275 static struct super_operations fuse_super_operations = {
 276         .alloc_inode    = fuse_alloc_inode,
 277         .destroy_inode  = fuse_destroy_inode,
 278         .read_inode     = fuse_read_inode,
 279         .clear_inode    = fuse_clear_inode,
 280         .put_super      = fuse_put_super,
 281         .show_options   = fuse_show_options,
 282 };
 283
 284 static int inc_mount_count(void)
 285 {
 286         int success = 0;
 287         spin_lock(&fuse_lock);
 288         mount_count ++;
 289         if (mount_max == -1 || mount_count <= mount_max)
 290                 success = 1;
 291         spin_unlock(&fuse_lock);
 292         return success;
 293 }
 294
 295 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 296 {
 297         struct fuse_conn *fc;
 298         struct inode *root;
 299         struct fuse_mount_data d;
 300         struct file *file;
 301         int err;
 302
 303         if (!parse_fuse_opt((char *) data, &d))
 304                 return -EINVAL;
 305
 306         sb->s_blocksize = PAGE_CACHE_SIZE;
 307         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 308         sb->s_magic = FUSE_SUPER_MAGIC;
 309         sb->s_op = &fuse_super_operations;
 310         sb->s_maxbytes = MAX_LFS_FILESIZE;
 311
 312         file = fget(d.fd);
 313         if (!file)
 314                 return -EINVAL;
 315
 316         fc = get_conn(file, sb);
 317         fput(file);
 318         if (fc == NULL)
 319                 return -EINVAL;
 320
 321         fc->user_id = d.user_id;
 322
 323         *get_fuse_conn_super_p(sb) = fc;
 324
 325         err = -ENFILE;
 326         if (!inc_mount_count() && current->uid != 0)
 327                 goto err;
 328
 329         err = -ENOMEM;
 330         root = get_root_inode(sb, d.rootmode);
 331         if (root == NULL)
 332                 goto err;
 333
 334         sb->s_root = d_alloc_root(root);
 335         if (!sb->s_root) {
 336                 iput(root);
 337                 goto err;
 338         }
 339         return 0;
 340
 341  err:
 342         spin_lock(&fuse_lock);
 343         mount_count --;
 344         fc->sb = NULL;
 345         fuse_release_conn(fc);
 346         spin_unlock(&fuse_lock);
 347         *get_fuse_conn_super_p(sb) = NULL;
 348         return err;
 349 }
 350
 351 static struct super_block *fuse_get_sb(struct file_system_type *fs_type,
 352                                        int flags, const char *dev_name,
 353                                        void *raw_data)
 354 {
 355         return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super);
 356 }
 357
 358 static struct file_system_type fuse_fs_type = {
 359         .owner          = THIS_MODULE,
 360         .name           = "fuse",
 361         .get_sb         = fuse_get_sb,
 362         .kill_sb        = kill_anon_super,
 363 };
 364
 365 static void fuse_inode_init_once(void *foo, kmem_cache_t *cachep,
 366                                  unsigned long flags)
 367 {
 368         struct inode * inode = foo;
 369
 370         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 371             SLAB_CTOR_CONSTRUCTOR)
 372                 inode_init_once(inode);
 373 }
 374
 375 static int __init fuse_fs_init(void)
 376 {
 377         int err;
 378
 379         err = register_filesystem(&fuse_fs_type);
 380         if (err)
 381                 printk("fuse: failed to register filesystem\n");
 382         else {
 383                 fuse_inode_cachep = kmem_cache_create("fuse_inode",
 384                                                       sizeof(struct fuse_inode),
 385                                                       0, SLAB_HWCACHE_ALIGN,
 386                                                       fuse_inode_init_once, NULL);
 387                 if (!fuse_inode_cachep) {
 388                         unregister_filesystem(&fuse_fs_type);
 389                         err = -ENOMEM;
 390                 }
 391         }
 392
 393         return err;
 394 }
 395
 396 static void fuse_fs_cleanup(void)
 397 {
 398         unregister_filesystem(&fuse_fs_type);
 399         kmem_cache_destroy(fuse_inode_cachep);
 400 }
 401
 402 static int __init fuse_init(void)
 403 {
 404         int res;
 405
 406         printk("fuse init (API version %i.%i)\n",
 407                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
 408
 409         spin_lock_init(&fuse_lock);
 410         res = fuse_fs_init();
 411         if (res)
 412                 goto err;
 413
 414         return 0;
 415
 416  err:
 417         return res;
 418 }
 419
 420 static void __exit fuse_exit(void)
 421 {
 422         printk(KERN_DEBUG "fuse exit\n");
 423
 424         fuse_fs_cleanup();
 425 }
 426
 427 module_init(fuse_init);
 428 module_exit(fuse_exit);