fs/hppfs/hppfs.c

   1 /*
   2  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/ctype.h>
   7 #include <linux/dcache.h>
   8 #include <linux/file.h>
   9 #include <linux/fs.h>
  10 #include <linux/init.h>
  11 #include <linux/kernel.h>
  12 #include <linux/list.h>
  13 #include <linux/module.h>
  14 #include <linux/mount.h>
  15 #include <linux/slab.h>
  16 #include <linux/statfs.h>
  17 #include <linux/types.h>
  18 #include <linux/pid_namespace.h>
  19 #include <linux/namei.h>
  20 #include <asm/uaccess.h>
  21 #include "os.h"
  22
  23 static struct inode *get_inode(struct super_block *, struct dentry *);
  24
  25 struct hppfs_data {
  26         struct list_head list;
  27         char contents[PAGE_SIZE - sizeof(struct list_head)];
  28 };
  29
  30 struct hppfs_private {
  31         struct file *proc_file;
  32         int host_fd;
  33         loff_t len;
  34         struct hppfs_data *contents;
  35 };
  36
  37 struct hppfs_inode_info {
  38         struct dentry *proc_dentry;
  39         struct inode vfs_inode;
  40 };
  41
  42 static inline struct hppfs_inode_info *HPPFS_I(struct inode *inode)
  43 {
  44         return container_of(inode, struct hppfs_inode_info, vfs_inode);
  45 }
  46
  47 #define HPPFS_SUPER_MAGIC 0xb00000ee
  48
  49 static const struct super_operations hppfs_sbops;
  50
  51 static int is_pid(struct dentry *dentry)
  52 {
  53         struct super_block *sb;
  54         int i;
  55
  56         sb = dentry->d_sb;
  57         if (dentry->d_parent != sb->s_root)
  58                 return 0;
  59
  60         for (i = 0; i < dentry->d_name.len; i++) {
  61                 if (!isdigit(dentry->d_name.name[i]))
  62                         return 0;
  63         }
  64         return 1;
  65 }
  66
  67 static char *dentry_name(struct dentry *dentry, int extra)
  68 {
  69         struct dentry *parent;
  70         char *root, *name;
  71         const char *seg_name;
  72         int len, seg_len;
  73
  74         len = 0;
  75         parent = dentry;
  76         while (parent->d_parent != parent) {
  77                 if (is_pid(parent))
  78                         len += strlen("pid") + 1;
  79                 else len += parent->d_name.len + 1;
  80                 parent = parent->d_parent;
  81         }
  82
  83         root = "proc";
  84         len += strlen(root);
  85         name = kmalloc(len + extra + 1, GFP_KERNEL);
  86         if (name == NULL)
  87                 return NULL;
  88
  89         name[len] = '\0';
  90         parent = dentry;
  91         while (parent->d_parent != parent) {
  92                 if (is_pid(parent)) {
  93                         seg_name = "pid";
  94                         seg_len = strlen("pid");
  95                 }
  96                 else {
  97                         seg_name = parent->d_name.name;
  98                         seg_len = parent->d_name.len;
  99                 }
 100
 101                 len -= seg_len + 1;
 102                 name[len] = '/';
 103                 strncpy(&name[len + 1], seg_name, seg_len);
 104                 parent = parent->d_parent;
 105         }
 106         strncpy(name, root, strlen(root));
 107         return name;
 108 }
 109
 110 static int file_removed(struct dentry *dentry, const char *file)
 111 {
 112         char *host_file;
 113         int extra, fd;
 114
 115         extra = 0;
 116         if (file != NULL)
 117                 extra += strlen(file) + 1;
 118
 119         host_file = dentry_name(dentry, extra + strlen("/remove"));
 120         if (host_file == NULL) {
 121                 printk(KERN_ERR "file_removed : allocation failed\n");
 122                 return -ENOMEM;
 123         }
 124
 125         if (file != NULL) {
 126                 strcat(host_file, "/");
 127                 strcat(host_file, file);
 128         }
 129         strcat(host_file, "/remove");
 130
 131         fd = os_open_file(host_file, of_read(OPENFLAGS()), 0);
 132         kfree(host_file);
 133         if (fd > 0) {
 134                 os_close_file(fd);
 135                 return 1;
 136         }
 137         return 0;
 138 }
 139
 140 static struct dentry *hppfs_lookup(struct inode *ino, struct dentry *dentry,
 141                                    struct nameidata *nd)
 142 {
 143         struct dentry *proc_dentry, *parent;
 144         struct qstr *name = &dentry->d_name;
 145         struct inode *inode;
 146         int err, deleted;
 147
 148         deleted = file_removed(dentry, NULL);
 149         if (deleted < 0)
 150                 return ERR_PTR(deleted);
 151         else if (deleted)
 152                 return ERR_PTR(-ENOENT);
 153
 154         parent = HPPFS_I(ino)->proc_dentry;
 155         mutex_lock(&parent->d_inode->i_mutex);
 156         proc_dentry = lookup_one_len(name->name, parent, name->len);
 157         mutex_unlock(&parent->d_inode->i_mutex);
 158
 159         if (IS_ERR(proc_dentry))
 160                 return proc_dentry;
 161
 162         err = -ENOMEM;
 163         inode = get_inode(ino->i_sb, proc_dentry);
 164         if (!inode)
 165                 goto out;
 166
 167         d_add(dentry, inode);
 168         return NULL;
 169
 170  out:
 171         return ERR_PTR(err);
 172 }
 173
 174 static const struct inode_operations hppfs_file_iops = {
 175 };
 176
 177 static ssize_t read_proc(struct file *file, char __user *buf, ssize_t count,
 178                          loff_t *ppos, int is_user)
 179 {
 180         ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
 181         ssize_t n;
 182
 183         read = file->f_path.dentry->d_inode->i_fop->read;
 184
 185         if (!is_user)
 186                 set_fs(KERNEL_DS);
 187
 188         n = (*read)(file, buf, count, &file->f_pos);
 189
 190         if (!is_user)
 191                 set_fs(USER_DS);
 192
 193         if (ppos)
 194                 *ppos = file->f_pos;
 195         return n;
 196 }
 197
 198 static ssize_t hppfs_read_file(int fd, char __user *buf, ssize_t count)
 199 {
 200         ssize_t n;
 201         int cur, err;
 202         char *new_buf;
 203
 204         n = -ENOMEM;
 205         new_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 206         if (new_buf == NULL) {
 207                 printk(KERN_ERR "hppfs_read_file : kmalloc failed\n");
 208                 goto out;
 209         }
 210         n = 0;
 211         while (count > 0) {
 212                 cur = min_t(ssize_t, count, PAGE_SIZE);
 213                 err = os_read_file(fd, new_buf, cur);
 214                 if (err < 0) {
 215                         printk(KERN_ERR "hppfs_read : read failed, "
 216                                "errno = %d\n", err);
 217                         n = err;
 218                         goto out_free;
 219                 } else if (err == 0)
 220                         break;
 221
 222                 if (copy_to_user(buf, new_buf, err)) {
 223                         n = -EFAULT;
 224                         goto out_free;
 225                 }
 226                 n += err;
 227                 count -= err;
 228         }
 229  out_free:
 230         kfree(new_buf);
 231  out:
 232         return n;
 233 }
 234
 235 static ssize_t hppfs_read(struct file *file, char __user *buf, size_t count,
 236                           loff_t *ppos)
 237 {
 238         struct hppfs_private *hppfs = file->private_data;
 239         struct hppfs_data *data;
 240         loff_t off;
 241         int err;
 242
 243         if (hppfs->contents != NULL) {
 244                 int rem;
 245
 246                 if (*ppos >= hppfs->len)
 247                         return 0;
 248
 249                 data = hppfs->contents;
 250                 off = *ppos;
 251                 while (off >= sizeof(data->contents)) {
 252                         data = list_entry(data->list.next, struct hppfs_data,
 253                                           list);
 254                         off -= sizeof(data->contents);
 255                 }
 256
 257                 if (off + count > hppfs->len)
 258                         count = hppfs->len - off;
 259                 rem = copy_to_user(buf, &data->contents[off], count);
 260                 *ppos += count - rem;
 261                 if (rem > 0)
 262                         return -EFAULT;
 263         } else if (hppfs->host_fd != -1) {
 264                 err = os_seek_file(hppfs->host_fd, *ppos);
 265                 if (err) {
 266                         printk(KERN_ERR "hppfs_read : seek failed, "
 267                                "errno = %d\n", err);
 268                         return err;
 269                 }
 270                 err = hppfs_read_file(hppfs->host_fd, buf, count);
 271                 if (err < 0) {
 272                         printk(KERN_ERR "hppfs_read: read failed: %d\n", err);
 273                         return err;
 274                 }
 275                 count = err;
 276                 if (count > 0)
 277                         *ppos += count;
 278         }
 279         else count = read_proc(hppfs->proc_file, buf, count, ppos, 1);
 280
 281         return count;
 282 }
 283
 284 static ssize_t hppfs_write(struct file *file, const char __user *buf,
 285                            size_t len, loff_t *ppos)
 286 {
 287         struct hppfs_private *data = file->private_data;
 288         struct file *proc_file = data->proc_file;
 289         ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
 290
 291         write = proc_file->f_path.dentry->d_inode->i_fop->write;
 292         return (*write)(proc_file, buf, len, ppos);
 293 }
 294
 295 static int open_host_sock(char *host_file, int *filter_out)
 296 {
 297         char *end;
 298         int fd;
 299
 300         end = &host_file[strlen(host_file)];
 301         strcpy(end, "/rw");
 302         *filter_out = 1;
 303         fd = os_connect_socket(host_file);
 304         if (fd > 0)
 305                 return fd;
 306
 307         strcpy(end, "/r");
 308         *filter_out = 0;
 309         fd = os_connect_socket(host_file);
 310         return fd;
 311 }
 312
 313 static void free_contents(struct hppfs_data *head)
 314 {
 315         struct hppfs_data *data;
 316         struct list_head *ele, *next;
 317
 318         if (head == NULL)
 319                 return;
 320
 321         list_for_each_safe(ele, next, &head->list) {
 322                 data = list_entry(ele, struct hppfs_data, list);
 323                 kfree(data);
 324         }
 325         kfree(head);
 326 }
 327
 328 static struct hppfs_data *hppfs_get_data(int fd, int filter,
 329                                          struct file *proc_file,
 330                                          struct file *hppfs_file,
 331                                          loff_t *size_out)
 332 {
 333         struct hppfs_data *data, *new, *head;
 334         int n, err;
 335
 336         err = -ENOMEM;
 337         data = kmalloc(sizeof(*data), GFP_KERNEL);
 338         if (data == NULL) {
 339                 printk(KERN_ERR "hppfs_get_data : head allocation failed\n");
 340                 goto failed;
 341         }
 342
 343         INIT_LIST_HEAD(&data->list);
 344
 345         head = data;
 346         *size_out = 0;
 347
 348         if (filter) {
 349                 while ((n = read_proc(proc_file, data->contents,
 350                                       sizeof(data->contents), NULL, 0)) > 0)
 351                         os_write_file(fd, data->contents, n);
 352                 err = os_shutdown_socket(fd, 0, 1);
 353                 if (err) {
 354                         printk(KERN_ERR "hppfs_get_data : failed to shut down "
 355                                "socket\n");
 356                         goto failed_free;
 357                 }
 358         }
 359         while (1) {
 360                 n = os_read_file(fd, data->contents, sizeof(data->contents));
 361                 if (n < 0) {
 362                         err = n;
 363                         printk(KERN_ERR "hppfs_get_data : read failed, "
 364                                "errno = %d\n", err);
 365                         goto failed_free;
 366                 } else if (n == 0)
 367                         break;
 368
 369                 *size_out += n;
 370
 371                 if (n < sizeof(data->contents))
 372                         break;
 373
 374                 new = kmalloc(sizeof(*data), GFP_KERNEL);
 375                 if (new == 0) {
 376                         printk(KERN_ERR "hppfs_get_data : data allocation "
 377                                "failed\n");
 378                         err = -ENOMEM;
 379                         goto failed_free;
 380                 }
 381
 382                 INIT_LIST_HEAD(&new->list);
 383                 list_add(&new->list, &data->list);
 384                 data = new;
 385         }
 386         return head;
 387
 388  failed_free:
 389         free_contents(head);
 390  failed:
 391         return ERR_PTR(err);
 392 }
 393
 394 static struct hppfs_private *hppfs_data(void)
 395 {
 396         struct hppfs_private *data;
 397
 398         data = kmalloc(sizeof(*data), GFP_KERNEL);
 399         if (data == NULL)
 400                 return data;
 401
 402         *data = ((struct hppfs_private ) { .host_fd             = -1,
 403                                            .len                 = -1,
 404                                            .contents            = NULL } );
 405         return data;
 406 }
 407
 408 static int file_mode(int fmode)
 409 {
 410         if (fmode == (FMODE_READ | FMODE_WRITE))
 411                 return O_RDWR;
 412         if (fmode == FMODE_READ)
 413                 return O_RDONLY;
 414         if (fmode == FMODE_WRITE)
 415                 return O_WRONLY;
 416         return 0;
 417 }
 418
 419 static int hppfs_open(struct inode *inode, struct file *file)
 420 {
 421         const struct cred *cred = file->f_cred;
 422         struct hppfs_private *data;
 423         struct vfsmount *proc_mnt;
 424         struct dentry *proc_dentry;
 425         char *host_file;
 426         int err, fd, type, filter;
 427
 428         err = -ENOMEM;
 429         data = hppfs_data();
 430         if (data == NULL)
 431                 goto out;
 432
 433         host_file = dentry_name(file->f_path.dentry, strlen("/rw"));
 434         if (host_file == NULL)
 435                 goto out_free2;
 436
 437         proc_dentry = HPPFS_I(inode)->proc_dentry;
 438         proc_mnt = inode->i_sb->s_fs_info;
 439
 440         /* XXX This isn't closed anywhere */
 441         data->proc_file = dentry_open(dget(proc_dentry), mntget(proc_mnt),
 442                                       file_mode(file->f_mode), cred);
 443         err = PTR_ERR(data->proc_file);
 444         if (IS_ERR(data->proc_file))
 445                 goto out_free1;
 446
 447         type = os_file_type(host_file);
 448         if (type == OS_TYPE_FILE) {
 449                 fd = os_open_file(host_file, of_read(OPENFLAGS()), 0);
 450                 if (fd >= 0)
 451                         data->host_fd = fd;
 452                 else
 453                         printk(KERN_ERR "hppfs_open : failed to open '%s', "
 454                                "errno = %d\n", host_file, -fd);
 455
 456                 data->contents = NULL;
 457         } else if (type == OS_TYPE_DIR) {
 458                 fd = open_host_sock(host_file, &filter);
 459                 if (fd > 0) {
 460                         data->contents = hppfs_get_data(fd, filter,
 461                                                         data->proc_file,
 462                                                         file, &data->len);
 463                         if (!IS_ERR(data->contents))
 464                                 data->host_fd = fd;
 465                 } else
 466                         printk(KERN_ERR "hppfs_open : failed to open a socket "
 467                                "in '%s', errno = %d\n", host_file, -fd);
 468         }
 469         kfree(host_file);
 470
 471         file->private_data = data;
 472         return 0;
 473
 474  out_free1:
 475         kfree(host_file);
 476  out_free2:
 477         free_contents(data->contents);
 478         kfree(data);
 479  out:
 480         return err;
 481 }
 482
 483 static int hppfs_dir_open(struct inode *inode, struct file *file)
 484 {
 485         const struct cred *cred = file->f_cred;
 486         struct hppfs_private *data;
 487         struct vfsmount *proc_mnt;
 488         struct dentry *proc_dentry;
 489         int err;
 490
 491         err = -ENOMEM;
 492         data = hppfs_data();
 493         if (data == NULL)
 494                 goto out;
 495
 496         proc_dentry = HPPFS_I(inode)->proc_dentry;
 497         proc_mnt = inode->i_sb->s_fs_info;
 498         data->proc_file = dentry_open(dget(proc_dentry), mntget(proc_mnt),
 499                                       file_mode(file->f_mode), cred);
 500         err = PTR_ERR(data->proc_file);
 501         if (IS_ERR(data->proc_file))
 502                 goto out_free;
 503
 504         file->private_data = data;
 505         return 0;
 506
 507  out_free:
 508         kfree(data);
 509  out:
 510         return err;
 511 }
 512
 513 static loff_t hppfs_llseek(struct file *file, loff_t off, int where)
 514 {
 515         struct hppfs_private *data = file->private_data;
 516         struct file *proc_file = data->proc_file;
 517         loff_t (*llseek)(struct file *, loff_t, int);
 518         loff_t ret;
 519
 520         llseek = proc_file->f_path.dentry->d_inode->i_fop->llseek;
 521         if (llseek != NULL) {
 522                 ret = (*llseek)(proc_file, off, where);
 523                 if (ret < 0)
 524                         return ret;
 525         }
 526
 527         return default_llseek(file, off, where);
 528 }
 529
 530 static const struct file_operations hppfs_file_fops = {
 531         .owner          = NULL,
 532         .llseek         = hppfs_llseek,
 533         .read           = hppfs_read,
 534         .write          = hppfs_write,
 535         .open           = hppfs_open,
 536 };
 537
 538 struct hppfs_dirent {
 539         void *vfs_dirent;
 540         filldir_t filldir;
 541         struct dentry *dentry;
 542 };
 543
 544 static int hppfs_filldir(void *d, const char *name, int size,
 545                          loff_t offset, u64 inode, unsigned int type)
 546 {
 547         struct hppfs_dirent *dirent = d;
 548
 549         if (file_removed(dirent->dentry, name))
 550                 return 0;
 551
 552         return (*dirent->filldir)(dirent->vfs_dirent, name, size, offset,
 553                                   inode, type);
 554 }
 555
 556 static int hppfs_readdir(struct file *file, void *ent, filldir_t filldir)
 557 {
 558         struct hppfs_private *data = file->private_data;
 559         struct file *proc_file = data->proc_file;
 560         int (*readdir)(struct file *, void *, filldir_t);
 561         struct hppfs_dirent dirent = ((struct hppfs_dirent)
 562                                       { .vfs_dirent     = ent,
 563                                         .filldir        = filldir,
 564                                         .dentry         = file->f_path.dentry
 565                                       });
 566         int err;
 567
 568         readdir = proc_file->f_path.dentry->d_inode->i_fop->readdir;
 569
 570         proc_file->f_pos = file->f_pos;
 571         err = (*readdir)(proc_file, &dirent, hppfs_filldir);
 572         file->f_pos = proc_file->f_pos;
 573
 574         return err;
 575 }
 576
 577 static int hppfs_fsync(struct file *file, loff_t start, loff_t end,
 578                        int datasync)
 579 {
 580         return filemap_write_and_wait_range(file->f_mapping, start, end);
 581 }
 582
 583 static const struct file_operations hppfs_dir_fops = {
 584         .owner          = NULL,
 585         .readdir        = hppfs_readdir,
 586         .open           = hppfs_dir_open,
 587         .fsync          = hppfs_fsync,
 588         .llseek         = default_llseek,
 589 };
 590
 591 static int hppfs_statfs(struct dentry *dentry, struct kstatfs *sf)
 592 {
 593         sf->f_blocks = 0;
 594         sf->f_bfree = 0;
 595         sf->f_bavail = 0;
 596         sf->f_files = 0;
 597         sf->f_ffree = 0;
 598         sf->f_type = HPPFS_SUPER_MAGIC;
 599         return 0;
 600 }
 601
 602 static struct inode *hppfs_alloc_inode(struct super_block *sb)
 603 {
 604         struct hppfs_inode_info *hi;
 605
 606         hi = kmalloc(sizeof(*hi), GFP_KERNEL);
 607         if (!hi)
 608                 return NULL;
 609
 610         hi->proc_dentry = NULL;
 611         inode_init_once(&hi->vfs_inode);
 612         return &hi->vfs_inode;
 613 }
 614
 615 void hppfs_evict_inode(struct inode *ino)
 616 {
 617         end_writeback(ino);
 618         dput(HPPFS_I(ino)->proc_dentry);
 619         mntput(ino->i_sb->s_fs_info);
 620 }
 621
 622 static void hppfs_i_callback(struct rcu_head *head)
 623 {
 624         struct inode *inode = container_of(head, struct inode, i_rcu);
 625         INIT_LIST_HEAD(&inode->i_dentry);
 626         kfree(HPPFS_I(inode));
 627 }
 628
 629 static void hppfs_destroy_inode(struct inode *inode)
 630 {
 631         call_rcu(&inode->i_rcu, hppfs_i_callback);
 632 }
 633
 634 static const struct super_operations hppfs_sbops = {
 635         .alloc_inode    = hppfs_alloc_inode,
 636         .destroy_inode  = hppfs_destroy_inode,
 637         .evict_inode    = hppfs_evict_inode,
 638         .statfs         = hppfs_statfs,
 639 };
 640
 641 static int hppfs_readlink(struct dentry *dentry, char __user *buffer,
 642                           int buflen)
 643 {
 644         struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;
 645         return proc_dentry->d_inode->i_op->readlink(proc_dentry, buffer,
 646                                                     buflen);
 647 }
 648
 649 static void *hppfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 650 {
 651         struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;
 652
 653         return proc_dentry->d_inode->i_op->follow_link(proc_dentry, nd);
 654 }
 655
 656 static void hppfs_put_link(struct dentry *dentry, struct nameidata *nd,
 657                            void *cookie)
 658 {
 659         struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;
 660
 661         if (proc_dentry->d_inode->i_op->put_link)
 662                 proc_dentry->d_inode->i_op->put_link(proc_dentry, nd, cookie);
 663 }
 664
 665 static const struct inode_operations hppfs_dir_iops = {
 666         .lookup         = hppfs_lookup,
 667 };
 668
 669 static const struct inode_operations hppfs_link_iops = {
 670         .readlink       = hppfs_readlink,
 671         .follow_link    = hppfs_follow_link,
 672         .put_link       = hppfs_put_link,
 673 };
 674
 675 static struct inode *get_inode(struct super_block *sb, struct dentry *dentry)
 676 {
 677         struct inode *proc_ino = dentry->d_inode;
 678         struct inode *inode = new_inode(sb);
 679
 680         if (!inode) {
 681                 dput(dentry);
 682                 return ERR_PTR(-ENOMEM);
 683         }
 684
 685         if (S_ISDIR(dentry->d_inode->i_mode)) {
 686                 inode->i_op = &hppfs_dir_iops;
 687                 inode->i_fop = &hppfs_dir_fops;
 688         } else if (S_ISLNK(dentry->d_inode->i_mode)) {
 689                 inode->i_op = &hppfs_link_iops;
 690                 inode->i_fop = &hppfs_file_fops;
 691         } else {
 692                 inode->i_op = &hppfs_file_iops;
 693                 inode->i_fop = &hppfs_file_fops;
 694         }
 695
 696         HPPFS_I(inode)->proc_dentry = dentry;
 697
 698         inode->i_uid = proc_ino->i_uid;
 699         inode->i_gid = proc_ino->i_gid;
 700         inode->i_atime = proc_ino->i_atime;
 701         inode->i_mtime = proc_ino->i_mtime;
 702         inode->i_ctime = proc_ino->i_ctime;
 703         inode->i_ino = proc_ino->i_ino;
 704         inode->i_mode = proc_ino->i_mode;
 705         inode->i_nlink = proc_ino->i_nlink;
 706         inode->i_size = proc_ino->i_size;
 707         inode->i_blocks = proc_ino->i_blocks;
 708
 709         return inode;
 710 }
 711
 712 static int hppfs_fill_super(struct super_block *sb, void *d, int silent)
 713 {
 714         struct inode *root_inode;
 715         struct vfsmount *proc_mnt;
 716         int err = -ENOENT;
 717
 718         proc_mnt = mntget(current->nsproxy->pid_ns->proc_mnt);
 719         if (IS_ERR(proc_mnt))
 720                 goto out;
 721
 722         sb->s_blocksize = 1024;
 723         sb->s_blocksize_bits = 10;
 724         sb->s_magic = HPPFS_SUPER_MAGIC;
 725         sb->s_op = &hppfs_sbops;
 726         sb->s_fs_info = proc_mnt;
 727
 728         err = -ENOMEM;
 729         root_inode = get_inode(sb, dget(proc_mnt->mnt_sb->s_root));
 730         if (!root_inode)
 731                 goto out_mntput;
 732
 733         sb->s_root = d_alloc_root(root_inode);
 734         if (!sb->s_root)
 735                 goto out_iput;
 736
 737         return 0;
 738
 739  out_iput:
 740         iput(root_inode);
 741  out_mntput:
 742         mntput(proc_mnt);
 743  out:
 744         return(err);
 745 }
 746
 747 static struct dentry *hppfs_read_super(struct file_system_type *type,
 748                             int flags, const char *dev_name,
 749                             void *data)
 750 {
 751         return mount_nodev(type, flags, data, hppfs_fill_super);
 752 }
 753
 754 static struct file_system_type hppfs_type = {
 755         .owner          = THIS_MODULE,
 756         .name           = "hppfs",
 757         .mount          = hppfs_read_super,
 758         .kill_sb        = kill_anon_super,
 759         .fs_flags       = 0,
 760 };
 761
 762 static int __init init_hppfs(void)
 763 {
 764         return register_filesystem(&hppfs_type);
 765 }
 766
 767 static void __exit exit_hppfs(void)
 768 {
 769         unregister_filesystem(&hppfs_type);
 770 }
 771
 772 module_init(init_hppfs)
 773 module_exit(exit_hppfs)
 774 MODULE_LICENSE("GPL");