fs/coda/dir.c

   1
   2 /*
   3  * Directory operations for Coda filesystem
   4  * Original version: (C) 1996 P. Braam and M. Callahan
   5  * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
   6  *
   7  * Carnegie Mellon encourages users to contribute improvements to
   8  * the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/kernel.h>
  13 #include <linux/time.h>
  14 #include <linux/fs.h>
  15 #include <linux/file.h>
  16 #include <linux/stat.h>
  17 #include <linux/errno.h>
  18 #include <linux/string.h>
  19 #include <linux/smp_lock.h>
  20
  21 #include <asm/uaccess.h>
  22
  23 #include <linux/coda.h>
  24 #include <linux/coda_linux.h>
  25 #include <linux/coda_psdev.h>
  26 #include <linux/coda_fs_i.h>
  27 #include <linux/coda_cache.h>
  28
  29 #include "coda_int.h"
  30
  31 /* dir inode-ops */
  32 static int coda_create(struct inode *dir, struct dentry *new, int mode, struct nameidata *nd);
  33 static struct dentry *coda_lookup(struct inode *dir, struct dentry *target, struct nameidata *nd);
  34 static int coda_link(struct dentry *old_dentry, struct inode *dir_inode,
  35                      struct dentry *entry);
  36 static int coda_unlink(struct inode *dir_inode, struct dentry *entry);
  37 static int coda_symlink(struct inode *dir_inode, struct dentry *entry,
  38                         const char *symname);
  39 static int coda_mkdir(struct inode *dir_inode, struct dentry *entry, int mode);
  40 static int coda_rmdir(struct inode *dir_inode, struct dentry *entry);
  41 static int coda_rename(struct inode *old_inode, struct dentry *old_dentry,
  42                        struct inode *new_inode, struct dentry *new_dentry);
  43
  44 /* dir file-ops */
  45 static int coda_readdir(struct file *file, void *buf, filldir_t filldir);
  46
  47 /* dentry ops */
  48 static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd);
  49 static int coda_dentry_delete(struct dentry *);
  50
  51 /* support routines */
  52 static int coda_venus_readdir(struct file *coda_file, void *buf,
  53                               filldir_t filldir);
  54
  55 /* same as fs/bad_inode.c */
  56 static int coda_return_EIO(void)
  57 {
  58         return -EIO;
  59 }
  60 #define CODA_EIO_ERROR ((void *) (coda_return_EIO))
  61
  62 static const struct dentry_operations coda_dentry_operations =
  63 {
  64         .d_revalidate   = coda_dentry_revalidate,
  65         .d_delete       = coda_dentry_delete,
  66 };
  67
  68 const struct inode_operations coda_dir_inode_operations =
  69 {
  70         .create         = coda_create,
  71         .lookup         = coda_lookup,
  72         .link           = coda_link,
  73         .unlink         = coda_unlink,
  74         .symlink        = coda_symlink,
  75         .mkdir          = coda_mkdir,
  76         .rmdir          = coda_rmdir,
  77         .mknod          = CODA_EIO_ERROR,
  78         .rename         = coda_rename,
  79         .permission     = coda_permission,
  80         .getattr        = coda_getattr,
  81         .setattr        = coda_setattr,
  82 };
  83
  84 const struct file_operations coda_dir_operations = {
  85         .llseek         = generic_file_llseek,
  86         .read           = generic_read_dir,
  87         .readdir        = coda_readdir,
  88         .open           = coda_open,
  89         .release        = coda_release,
  90         .fsync          = coda_fsync,
  91 };
  92
  93
  94 /* inode operations for directories */
  95 /* access routines: lookup, readlink, permission */
  96 static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, struct nameidata *nd)
  97 {
  98         struct inode *inode = NULL;
  99         struct CodaFid resfid = { { 0, } };
 100         int type = 0;
 101         int error = 0;
 102         const char *name = entry->d_name.name;
 103         size_t length = entry->d_name.len;
 104
 105         if (length > CODA_MAXNAMLEN) {
 106                 printk(KERN_ERR "name too long: lookup, %s (%*s)\n",
 107                        coda_i2s(dir), (int)length, name);
 108                 return ERR_PTR(-ENAMETOOLONG);
 109         }
 110
 111         /* control object, create inode on the fly */
 112         if (coda_isroot(dir) && coda_iscontrol(name, length)) {
 113                 error = coda_cnode_makectl(&inode, dir->i_sb);
 114                 type = CODA_NOCACHE;
 115                 goto exit;
 116         }
 117
 118         lock_kernel();
 119
 120         error = venus_lookup(dir->i_sb, coda_i2f(dir), name, length,
 121                              &type, &resfid);
 122         if (!error)
 123                 error = coda_cnode_make(&inode, &resfid, dir->i_sb);
 124
 125         unlock_kernel();
 126
 127         if (error && error != -ENOENT)
 128                 return ERR_PTR(error);
 129
 130 exit:
 131         entry->d_op = &coda_dentry_operations;
 132
 133         if (inode && (type & CODA_NOCACHE))
 134                 coda_flag_inode(inode, C_VATTR | C_PURGE);
 135
 136         return d_splice_alias(inode, entry);
 137 }
 138
 139
 140 int coda_permission(struct inode *inode, int mask)
 141 {
 142         int error = 0;
 143
 144         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 145
 146         if (!mask)
 147                 return 0;
 148
 149         if ((mask & MAY_EXEC) && !execute_ok(inode))
 150                 return -EACCES;
 151
 152         lock_kernel();
 153
 154         if (coda_cache_check(inode, mask))
 155                 goto out;
 156
 157         error = venus_access(inode->i_sb, coda_i2f(inode), mask);
 158
 159         if (!error)
 160                 coda_cache_enter(inode, mask);
 161
 162  out:
 163         unlock_kernel();
 164         return error;
 165 }
 166
 167
 168 static inline void coda_dir_update_mtime(struct inode *dir)
 169 {
 170 #ifdef REQUERY_VENUS_FOR_MTIME
 171         /* invalidate the directory cnode's attributes so we refetch the
 172          * attributes from venus next time the inode is referenced */
 173         coda_flag_inode(dir, C_VATTR);
 174 #else
 175         /* optimistically we can also act as if our nose bleeds. The
 176          * granularity of the mtime is coarse anyways so we might actually be
 177          * right most of the time. Note: we only do this for directories. */
 178         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 179 #endif
 180 }
 181
 182 /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
 183  * trick to fool GNU find's optimizations. If we can't be sure of the link
 184  * (because of volume mount points) we set i_nlink to 1 which forces find
 185  * to consider every child as a possible directory. We should also never
 186  * see an increment or decrement for deleted directories where i_nlink == 0 */
 187 static inline void coda_dir_inc_nlink(struct inode *dir)
 188 {
 189         if (dir->i_nlink >= 2)
 190                 inc_nlink(dir);
 191 }
 192
 193 static inline void coda_dir_drop_nlink(struct inode *dir)
 194 {
 195         if (dir->i_nlink > 2)
 196                 drop_nlink(dir);
 197 }
 198
 199 /* creation routines: create, mknod, mkdir, link, symlink */
 200 static int coda_create(struct inode *dir, struct dentry *de, int mode, struct nameidata *nd)
 201 {
 202         int error=0;
 203         const char *name=de->d_name.name;
 204         int length=de->d_name.len;
 205         struct inode *inode;
 206         struct CodaFid newfid;
 207         struct coda_vattr attrs;
 208
 209         lock_kernel();
 210
 211         if (coda_isroot(dir) && coda_iscontrol(name, length)) {
 212                 unlock_kernel();
 213                 return -EPERM;
 214         }
 215
 216         error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
 217                                 0, mode, &newfid, &attrs);
 218
 219         if ( error ) {
 220                 unlock_kernel();
 221                 d_drop(de);
 222                 return error;
 223         }
 224
 225         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 226         if ( IS_ERR(inode) ) {
 227                 unlock_kernel();
 228                 d_drop(de);
 229                 return PTR_ERR(inode);
 230         }
 231
 232         /* invalidate the directory cnode's attributes */
 233         coda_dir_update_mtime(dir);
 234         unlock_kernel();
 235         d_instantiate(de, inode);
 236         return 0;
 237 }
 238
 239 static int coda_mkdir(struct inode *dir, struct dentry *de, int mode)
 240 {
 241         struct inode *inode;
 242         struct coda_vattr attrs;
 243         const char *name = de->d_name.name;
 244         int len = de->d_name.len;
 245         int error;
 246         struct CodaFid newfid;
 247
 248         lock_kernel();
 249
 250         if (coda_isroot(dir) && coda_iscontrol(name, len)) {
 251                 unlock_kernel();
 252                 return -EPERM;
 253         }
 254
 255         attrs.va_mode = mode;
 256         error = venus_mkdir(dir->i_sb, coda_i2f(dir),
 257                                name, len, &newfid, &attrs);
 258
 259         if ( error ) {
 260                 unlock_kernel();
 261                 d_drop(de);
 262                 return error;
 263         }
 264
 265         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 266         if ( IS_ERR(inode) ) {
 267                 unlock_kernel();
 268                 d_drop(de);
 269                 return PTR_ERR(inode);
 270         }
 271
 272         /* invalidate the directory cnode's attributes */
 273         coda_dir_inc_nlink(dir);
 274         coda_dir_update_mtime(dir);
 275         unlock_kernel();
 276         d_instantiate(de, inode);
 277         return 0;
 278 }
 279
 280 /* try to make de an entry in dir_inodde linked to source_de */
 281 static int coda_link(struct dentry *source_de, struct inode *dir_inode,
 282           struct dentry *de)
 283 {
 284         struct inode *inode = source_de->d_inode;
 285         const char * name = de->d_name.name;
 286         int len = de->d_name.len;
 287         int error;
 288
 289         lock_kernel();
 290
 291         if (coda_isroot(dir_inode) && coda_iscontrol(name, len)) {
 292                 unlock_kernel();
 293                 return -EPERM;
 294         }
 295
 296         error = venus_link(dir_inode->i_sb, coda_i2f(inode),
 297                            coda_i2f(dir_inode), (const char *)name, len);
 298
 299         if (error) {
 300                 d_drop(de);
 301                 goto out;
 302         }
 303
 304         coda_dir_update_mtime(dir_inode);
 305         atomic_inc(&inode->i_count);
 306         d_instantiate(de, inode);
 307         inc_nlink(inode);
 308
 309 out:
 310         unlock_kernel();
 311         return(error);
 312 }
 313
 314
 315 static int coda_symlink(struct inode *dir_inode, struct dentry *de,
 316                         const char *symname)
 317 {
 318         const char *name = de->d_name.name;
 319         int len = de->d_name.len;
 320         int symlen;
 321         int error = 0;
 322
 323         lock_kernel();
 324
 325         if (coda_isroot(dir_inode) && coda_iscontrol(name, len)) {
 326                 unlock_kernel();
 327                 return -EPERM;
 328         }
 329
 330         symlen = strlen(symname);
 331         if ( symlen > CODA_MAXPATHLEN ) {
 332                 unlock_kernel();
 333                 return -ENAMETOOLONG;
 334         }
 335
 336         /*
 337          * This entry is now negative. Since we do not create
 338          * an inode for the entry we have to drop it.
 339          */
 340         d_drop(de);
 341         error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
 342                               symname, symlen);
 343
 344         /* mtime is no good anymore */
 345         if ( !error )
 346                 coda_dir_update_mtime(dir_inode);
 347
 348         unlock_kernel();
 349         return error;
 350 }
 351
 352 /* destruction routines: unlink, rmdir */
 353 static int coda_unlink(struct inode *dir, struct dentry *de)
 354 {
 355         int error;
 356         const char *name = de->d_name.name;
 357         int len = de->d_name.len;
 358
 359         lock_kernel();
 360
 361         error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
 362         if ( error ) {
 363                 unlock_kernel();
 364                 return error;
 365         }
 366
 367         coda_dir_update_mtime(dir);
 368         drop_nlink(de->d_inode);
 369         unlock_kernel();
 370         return 0;
 371 }
 372
 373 static int coda_rmdir(struct inode *dir, struct dentry *de)
 374 {
 375         const char *name = de->d_name.name;
 376         int len = de->d_name.len;
 377         int error;
 378
 379         lock_kernel();
 380
 381         error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
 382         if (!error) {
 383                 /* VFS may delete the child */
 384                 if (de->d_inode)
 385                     de->d_inode->i_nlink = 0;
 386
 387                 /* fix the link count of the parent */
 388                 coda_dir_drop_nlink(dir);
 389                 coda_dir_update_mtime(dir);
 390         }
 391         unlock_kernel();
 392         return error;
 393 }
 394
 395 /* rename */
 396 static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 397                        struct inode *new_dir, struct dentry *new_dentry)
 398 {
 399         const char *old_name = old_dentry->d_name.name;
 400         const char *new_name = new_dentry->d_name.name;
 401         int old_length = old_dentry->d_name.len;
 402         int new_length = new_dentry->d_name.len;
 403         int error;
 404
 405         lock_kernel();
 406
 407         error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
 408                              coda_i2f(new_dir), old_length, new_length,
 409                              (const char *) old_name, (const char *)new_name);
 410
 411         if ( !error ) {
 412                 if ( new_dentry->d_inode ) {
 413                         if ( S_ISDIR(new_dentry->d_inode->i_mode) ) {
 414                                 coda_dir_drop_nlink(old_dir);
 415                                 coda_dir_inc_nlink(new_dir);
 416                         }
 417                         coda_dir_update_mtime(old_dir);
 418                         coda_dir_update_mtime(new_dir);
 419                         coda_flag_inode(new_dentry->d_inode, C_VATTR);
 420                 } else {
 421                         coda_flag_inode(old_dir, C_VATTR);
 422                         coda_flag_inode(new_dir, C_VATTR);
 423                 }
 424         }
 425         unlock_kernel();
 426
 427         return error;
 428 }
 429
 430
 431 /* file operations for directories */
 432 static int coda_readdir(struct file *coda_file, void *buf, filldir_t filldir)
 433 {
 434         struct coda_file_info *cfi;
 435         struct file *host_file;
 436         int ret;
 437
 438         cfi = CODA_FTOC(coda_file);
 439         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 440         host_file = cfi->cfi_container;
 441
 442         if (!host_file->f_op)
 443                 return -ENOTDIR;
 444
 445         if (host_file->f_op->readdir)
 446         {
 447                 /* potemkin case: we were handed a directory inode.
 448                  * We can't use vfs_readdir because we have to keep the file
 449                  * position in sync between the coda_file and the host_file.
 450                  * and as such we need grab the inode mutex. */
 451                 struct inode *host_inode = host_file->f_path.dentry->d_inode;
 452
 453                 mutex_lock(&host_inode->i_mutex);
 454                 host_file->f_pos = coda_file->f_pos;
 455
 456                 ret = -ENOENT;
 457                 if (!IS_DEADDIR(host_inode)) {
 458                         ret = host_file->f_op->readdir(host_file, buf, filldir);
 459                         file_accessed(host_file);
 460                 }
 461
 462                 coda_file->f_pos = host_file->f_pos;
 463                 mutex_unlock(&host_inode->i_mutex);
 464         }
 465         else /* Venus: we must read Venus dirents from a file */
 466                 ret = coda_venus_readdir(coda_file, buf, filldir);
 467
 468         return ret;
 469 }
 470
 471 static inline unsigned int CDT2DT(unsigned char cdt)
 472 {
 473         unsigned int dt;
 474
 475         switch(cdt) {
 476         case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
 477         case CDT_FIFO:    dt = DT_FIFO;    break;
 478         case CDT_CHR:     dt = DT_CHR;     break;
 479         case CDT_DIR:     dt = DT_DIR;     break;
 480         case CDT_BLK:     dt = DT_BLK;     break;
 481         case CDT_REG:     dt = DT_REG;     break;
 482         case CDT_LNK:     dt = DT_LNK;     break;
 483         case CDT_SOCK:    dt = DT_SOCK;    break;
 484         case CDT_WHT:     dt = DT_WHT;     break;
 485         default:          dt = DT_UNKNOWN; break;
 486         }
 487         return dt;
 488 }
 489
 490 /* support routines */
 491 static int coda_venus_readdir(struct file *coda_file, void *buf,
 492                               filldir_t filldir)
 493 {
 494         int result = 0; /* # of entries returned */
 495         struct coda_file_info *cfi;
 496         struct coda_inode_info *cii;
 497         struct file *host_file;
 498         struct dentry *de;
 499         struct venus_dirent *vdir;
 500         unsigned long vdir_size =
 501             (unsigned long)(&((struct venus_dirent *)0)->d_name);
 502         unsigned int type;
 503         struct qstr name;
 504         ino_t ino;
 505         int ret;
 506
 507         cfi = CODA_FTOC(coda_file);
 508         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 509         host_file = cfi->cfi_container;
 510
 511         de = coda_file->f_path.dentry;
 512         cii = ITOC(de->d_inode);
 513
 514         vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
 515         if (!vdir) return -ENOMEM;
 516
 517         if (coda_file->f_pos == 0) {
 518                 ret = filldir(buf, ".", 1, 0, de->d_inode->i_ino, DT_DIR);
 519                 if (ret < 0)
 520                         goto out;
 521                 result++;
 522                 coda_file->f_pos++;
 523         }
 524         if (coda_file->f_pos == 1) {
 525                 ret = filldir(buf, "..", 2, 1, de->d_parent->d_inode->i_ino, DT_DIR);
 526                 if (ret < 0)
 527                         goto out;
 528                 result++;
 529                 coda_file->f_pos++;
 530         }
 531         while (1) {
 532                 /* read entries from the directory file */
 533                 ret = kernel_read(host_file, coda_file->f_pos - 2, (char *)vdir,
 534                                   sizeof(*vdir));
 535                 if (ret < 0) {
 536                         printk(KERN_ERR "coda readdir: read dir %s failed %d\n",
 537                                coda_f2s(&cii->c_fid), ret);
 538                         break;
 539                 }
 540                 if (ret == 0) break; /* end of directory file reached */
 541
 542                 /* catch truncated reads */
 543                 if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
 544                         printk(KERN_ERR "coda readdir: short read on %s\n",
 545                                coda_f2s(&cii->c_fid));
 546                         ret = -EBADF;
 547                         break;
 548                 }
 549                 /* validate whether the directory file actually makes sense */
 550                 if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
 551                         printk(KERN_ERR "coda readdir: invalid dir %s\n",
 552                                coda_f2s(&cii->c_fid));
 553                         ret = -EBADF;
 554                         break;
 555                 }
 556
 557                 name.len = vdir->d_namlen;
 558                 name.name = vdir->d_name;
 559
 560                 /* Make sure we skip '.' and '..', we already got those */
 561                 if (name.name[0] == '.' && (name.len == 1 ||
 562                     (vdir->d_name[1] == '.' && name.len == 2)))
 563                         vdir->d_fileno = name.len = 0;
 564
 565                 /* skip null entries */
 566                 if (vdir->d_fileno && name.len) {
 567                         /* try to look up this entry in the dcache, that way
 568                          * userspace doesn't have to worry about breaking
 569                          * getcwd by having mismatched inode numbers for
 570                          * internal volume mountpoints. */
 571                         ino = find_inode_number(de, &name);
 572                         if (!ino) ino = vdir->d_fileno;
 573
 574                         type = CDT2DT(vdir->d_type);
 575                         ret = filldir(buf, name.name, name.len,
 576                                       coda_file->f_pos, ino, type);
 577                         /* failure means no space for filling in this round */
 578                         if (ret < 0) break;
 579                         result++;
 580                 }
 581                 /* we'll always have progress because d_reclen is unsigned and
 582                  * we've already established it is non-zero. */
 583                 coda_file->f_pos += vdir->d_reclen;
 584         }
 585 out:
 586         kfree(vdir);
 587         return result ? result : ret;
 588 }
 589
 590 /* called when a cache lookup succeeds */
 591 static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
 592 {
 593         struct inode *inode = de->d_inode;
 594         struct coda_inode_info *cii;
 595
 596         if (!inode)
 597                 return 1;
 598         lock_kernel();
 599         if (coda_isroot(inode))
 600                 goto out;
 601         if (is_bad_inode(inode))
 602                 goto bad;
 603
 604         cii = ITOC(de->d_inode);
 605         if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
 606                 goto out;
 607
 608         shrink_dcache_parent(de);
 609
 610         /* propagate for a flush */
 611         if (cii->c_flags & C_FLUSH)
 612                 coda_flag_inode_children(inode, C_FLUSH);
 613
 614         if (atomic_read(&de->d_count) > 1)
 615                 /* pretend it's valid, but don't change the flags */
 616                 goto out;
 617
 618         /* clear the flags. */
 619         cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 620
 621 bad:
 622         unlock_kernel();
 623         return 0;
 624 out:
 625         unlock_kernel();
 626         return 1;
 627 }
 628
 629 /*
 630  * This is the callback from dput() when d_count is going to 0.
 631  * We use this to unhash dentries with bad inodes.
 632  */
 633 static int coda_dentry_delete(struct dentry * dentry)
 634 {
 635         int flags;
 636
 637         if (!dentry->d_inode)
 638                 return 0;
 639
 640         flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
 641         if (is_bad_inode(dentry->d_inode) || flags) {
 642                 return 1;
 643         }
 644         return 0;
 645 }
 646
 647
 648
 649 /*
 650  * This is called when we want to check if the inode has
 651  * changed on the server.  Coda makes this easy since the
 652  * cache manager Venus issues a downcall to the kernel when this
 653  * happens
 654  */
 655 int coda_revalidate_inode(struct dentry *dentry)
 656 {
 657         struct coda_vattr attr;
 658         int error = 0;
 659         int old_mode;
 660         ino_t old_ino;
 661         struct inode *inode = dentry->d_inode;
 662         struct coda_inode_info *cii = ITOC(inode);
 663
 664         lock_kernel();
 665         if ( !cii->c_flags )
 666                 goto ok;
 667
 668         if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
 669                 error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
 670                 if ( error )
 671                         goto return_bad;
 672
 673                 /* this inode may be lost if:
 674                    - it's ino changed
 675                    - type changes must be permitted for repair and
 676                    missing mount points.
 677                 */
 678                 old_mode = inode->i_mode;
 679                 old_ino = inode->i_ino;
 680                 coda_vattr_to_iattr(inode, &attr);
 681
 682                 if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
 683                         printk("Coda: inode %ld, fid %s changed type!\n",
 684                                inode->i_ino, coda_f2s(&(cii->c_fid)));
 685                 }
 686
 687                 /* the following can happen when a local fid is replaced
 688                    with a global one, here we lose and declare the inode bad */
 689                 if (inode->i_ino != old_ino)
 690                         goto return_bad;
 691
 692                 coda_flag_inode_children(inode, C_FLUSH);
 693                 cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 694         }
 695
 696 ok:
 697         unlock_kernel();
 698         return 0;
 699
 700 return_bad:
 701         unlock_kernel();
 702         return -EIO;
 703 }