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/slab.h>
  16 #include <linux/file.h>
  17 #include <linux/stat.h>
  18 #include <linux/errno.h>
  19 #include <linux/string.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/namei.h>
  22 #include <linux/uaccess.h>
  23
  24 #include <linux/coda.h>
  25 #include <linux/coda_psdev.h>
  26 #include "coda_linux.h"
  27 #include "coda_cache.h"
  28
  29 #include "coda_int.h"
  30
  31 /* same as fs/bad_inode.c */
  32 static int coda_return_EIO(void)
  33 {
  34         return -EIO;
  35 }
  36 #define CODA_EIO_ERROR ((void *) (coda_return_EIO))
  37
  38 /* inode operations for directories */
  39 /* access routines: lookup, readlink, permission */
  40 static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
  41 {
  42         struct super_block *sb = dir->i_sb;
  43         const char *name = entry->d_name.name;
  44         size_t length = entry->d_name.len;
  45         struct inode *inode;
  46         int type = 0;
  47
  48         if (length > CODA_MAXNAMLEN) {
  49                 pr_err("name too long: lookup, %s (%*s)\n",
  50                        coda_i2s(dir), (int)length, name);
  51                 return ERR_PTR(-ENAMETOOLONG);
  52         }
  53
  54         /* control object, create inode on the fly */
  55         if (is_root_inode(dir) && coda_iscontrol(name, length)) {
  56                 inode = coda_cnode_makectl(sb);
  57                 type = CODA_NOCACHE;
  58         } else {
  59                 struct CodaFid fid = { { 0, } };
  60                 int error = venus_lookup(sb, coda_i2f(dir), name, length,
  61                                      &type, &fid);
  62                 inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
  63         }
  64
  65         if (!IS_ERR(inode) && (type & CODA_NOCACHE))
  66                 coda_flag_inode(inode, C_VATTR | C_PURGE);
  67
  68         if (inode == ERR_PTR(-ENOENT))
  69                 inode = NULL;
  70
  71         return d_splice_alias(inode, entry);
  72 }
  73
  74
  75 int coda_permission(struct inode *inode, int mask)
  76 {
  77         int error;
  78
  79         if (mask & MAY_NOT_BLOCK)
  80                 return -ECHILD;
  81
  82         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
  83
  84         if (!mask)
  85                 return 0;
  86
  87         if ((mask & MAY_EXEC) && !execute_ok(inode))
  88                 return -EACCES;
  89
  90         if (coda_cache_check(inode, mask))
  91                 return 0;
  92
  93         error = venus_access(inode->i_sb, coda_i2f(inode), mask);
  94
  95         if (!error)
  96                 coda_cache_enter(inode, mask);
  97
  98         return error;
  99 }
 100
 101
 102 static inline void coda_dir_update_mtime(struct inode *dir)
 103 {
 104 #ifdef REQUERY_VENUS_FOR_MTIME
 105         /* invalidate the directory cnode's attributes so we refetch the
 106          * attributes from venus next time the inode is referenced */
 107         coda_flag_inode(dir, C_VATTR);
 108 #else
 109         /* optimistically we can also act as if our nose bleeds. The
 110          * granularity of the mtime is coarse anyways so we might actually be
 111          * right most of the time. Note: we only do this for directories. */
 112         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 113 #endif
 114 }
 115
 116 /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
 117  * trick to fool GNU find's optimizations. If we can't be sure of the link
 118  * (because of volume mount points) we set i_nlink to 1 which forces find
 119  * to consider every child as a possible directory. We should also never
 120  * see an increment or decrement for deleted directories where i_nlink == 0 */
 121 static inline void coda_dir_inc_nlink(struct inode *dir)
 122 {
 123         if (dir->i_nlink >= 2)
 124                 inc_nlink(dir);
 125 }
 126
 127 static inline void coda_dir_drop_nlink(struct inode *dir)
 128 {
 129         if (dir->i_nlink > 2)
 130                 drop_nlink(dir);
 131 }
 132
 133 /* creation routines: create, mknod, mkdir, link, symlink */
 134 static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
 135 {
 136         int error;
 137         const char *name=de->d_name.name;
 138         int length=de->d_name.len;
 139         struct inode *inode;
 140         struct CodaFid newfid;
 141         struct coda_vattr attrs;
 142
 143         if (is_root_inode(dir) && coda_iscontrol(name, length))
 144                 return -EPERM;
 145
 146         error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
 147                                 0, mode, &newfid, &attrs);
 148         if (error)
 149                 goto err_out;
 150
 151         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 152         if (IS_ERR(inode)) {
 153                 error = PTR_ERR(inode);
 154                 goto err_out;
 155         }
 156
 157         /* invalidate the directory cnode's attributes */
 158         coda_dir_update_mtime(dir);
 159         d_instantiate(de, inode);
 160         return 0;
 161 err_out:
 162         d_drop(de);
 163         return error;
 164 }
 165
 166 static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
 167 {
 168         struct inode *inode;
 169         struct coda_vattr attrs;
 170         const char *name = de->d_name.name;
 171         int len = de->d_name.len;
 172         int error;
 173         struct CodaFid newfid;
 174
 175         if (is_root_inode(dir) && coda_iscontrol(name, len))
 176                 return -EPERM;
 177
 178         attrs.va_mode = mode;
 179         error = venus_mkdir(dir->i_sb, coda_i2f(dir),
 180                                name, len, &newfid, &attrs);
 181         if (error)
 182                 goto err_out;
 183
 184         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 185         if (IS_ERR(inode)) {
 186                 error = PTR_ERR(inode);
 187                 goto err_out;
 188         }
 189
 190         /* invalidate the directory cnode's attributes */
 191         coda_dir_inc_nlink(dir);
 192         coda_dir_update_mtime(dir);
 193         d_instantiate(de, inode);
 194         return 0;
 195 err_out:
 196         d_drop(de);
 197         return error;
 198 }
 199
 200 /* try to make de an entry in dir_inodde linked to source_de */
 201 static int coda_link(struct dentry *source_de, struct inode *dir_inode,
 202           struct dentry *de)
 203 {
 204         struct inode *inode = d_inode(source_de);
 205         const char * name = de->d_name.name;
 206         int len = de->d_name.len;
 207         int error;
 208
 209         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 210                 return -EPERM;
 211
 212         error = venus_link(dir_inode->i_sb, coda_i2f(inode),
 213                            coda_i2f(dir_inode), (const char *)name, len);
 214         if (error) {
 215                 d_drop(de);
 216                 return error;
 217         }
 218
 219         coda_dir_update_mtime(dir_inode);
 220         ihold(inode);
 221         d_instantiate(de, inode);
 222         inc_nlink(inode);
 223         return 0;
 224 }
 225
 226
 227 static int coda_symlink(struct inode *dir_inode, struct dentry *de,
 228                         const char *symname)
 229 {
 230         const char *name = de->d_name.name;
 231         int len = de->d_name.len;
 232         int symlen;
 233         int error;
 234
 235         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 236                 return -EPERM;
 237
 238         symlen = strlen(symname);
 239         if (symlen > CODA_MAXPATHLEN)
 240                 return -ENAMETOOLONG;
 241
 242         /*
 243          * This entry is now negative. Since we do not create
 244          * an inode for the entry we have to drop it.
 245          */
 246         d_drop(de);
 247         error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
 248                               symname, symlen);
 249
 250         /* mtime is no good anymore */
 251         if (!error)
 252                 coda_dir_update_mtime(dir_inode);
 253
 254         return error;
 255 }
 256
 257 /* destruction routines: unlink, rmdir */
 258 static int coda_unlink(struct inode *dir, struct dentry *de)
 259 {
 260         int error;
 261         const char *name = de->d_name.name;
 262         int len = de->d_name.len;
 263
 264         error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
 265         if (error)
 266                 return error;
 267
 268         coda_dir_update_mtime(dir);
 269         drop_nlink(d_inode(de));
 270         return 0;
 271 }
 272
 273 static int coda_rmdir(struct inode *dir, struct dentry *de)
 274 {
 275         const char *name = de->d_name.name;
 276         int len = de->d_name.len;
 277         int error;
 278
 279         error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
 280         if (!error) {
 281                 /* VFS may delete the child */
 282                 if (d_really_is_positive(de))
 283                         clear_nlink(d_inode(de));
 284
 285                 /* fix the link count of the parent */
 286                 coda_dir_drop_nlink(dir);
 287                 coda_dir_update_mtime(dir);
 288         }
 289         return error;
 290 }
 291
 292 /* rename */
 293 static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 294                        struct inode *new_dir, struct dentry *new_dentry)
 295 {
 296         const char *old_name = old_dentry->d_name.name;
 297         const char *new_name = new_dentry->d_name.name;
 298         int old_length = old_dentry->d_name.len;
 299         int new_length = new_dentry->d_name.len;
 300         int error;
 301
 302         error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
 303                              coda_i2f(new_dir), old_length, new_length,
 304                              (const char *) old_name, (const char *)new_name);
 305         if (!error) {
 306                 if (d_really_is_positive(new_dentry)) {
 307                         if (d_is_dir(new_dentry)) {
 308                                 coda_dir_drop_nlink(old_dir);
 309                                 coda_dir_inc_nlink(new_dir);
 310                         }
 311                         coda_dir_update_mtime(old_dir);
 312                         coda_dir_update_mtime(new_dir);
 313                         coda_flag_inode(d_inode(new_dentry), C_VATTR);
 314                 } else {
 315                         coda_flag_inode(old_dir, C_VATTR);
 316                         coda_flag_inode(new_dir, C_VATTR);
 317                 }
 318         }
 319         return error;
 320 }
 321
 322 static inline unsigned int CDT2DT(unsigned char cdt)
 323 {
 324         unsigned int dt;
 325
 326         switch(cdt) {
 327         case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
 328         case CDT_FIFO:    dt = DT_FIFO;    break;
 329         case CDT_CHR:     dt = DT_CHR;     break;
 330         case CDT_DIR:     dt = DT_DIR;     break;
 331         case CDT_BLK:     dt = DT_BLK;     break;
 332         case CDT_REG:     dt = DT_REG;     break;
 333         case CDT_LNK:     dt = DT_LNK;     break;
 334         case CDT_SOCK:    dt = DT_SOCK;    break;
 335         case CDT_WHT:     dt = DT_WHT;     break;
 336         default:          dt = DT_UNKNOWN; break;
 337         }
 338         return dt;
 339 }
 340
 341 /* support routines */
 342 static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
 343 {
 344         struct coda_file_info *cfi;
 345         struct coda_inode_info *cii;
 346         struct file *host_file;
 347         struct venus_dirent *vdir;
 348         unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
 349         unsigned int type;
 350         struct qstr name;
 351         ino_t ino;
 352         int ret;
 353
 354         cfi = CODA_FTOC(coda_file);
 355         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 356         host_file = cfi->cfi_container;
 357
 358         cii = ITOC(file_inode(coda_file));
 359
 360         vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
 361         if (!vdir) return -ENOMEM;
 362
 363         if (!dir_emit_dots(coda_file, ctx))
 364                 goto out;
 365
 366         while (1) {
 367                 /* read entries from the directory file */
 368                 ret = kernel_read(host_file, ctx->pos - 2, (char *)vdir,
 369                                   sizeof(*vdir));
 370                 if (ret < 0) {
 371                         pr_err("%s: read dir %s failed %d\n",
 372                                __func__, coda_f2s(&cii->c_fid), ret);
 373                         break;
 374                 }
 375                 if (ret == 0) break; /* end of directory file reached */
 376
 377                 /* catch truncated reads */
 378                 if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
 379                         pr_err("%s: short read on %s\n",
 380                                __func__, coda_f2s(&cii->c_fid));
 381                         ret = -EBADF;
 382                         break;
 383                 }
 384                 /* validate whether the directory file actually makes sense */
 385                 if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
 386                         pr_err("%s: invalid dir %s\n",
 387                                __func__, coda_f2s(&cii->c_fid));
 388                         ret = -EBADF;
 389                         break;
 390                 }
 391
 392                 name.len = vdir->d_namlen;
 393                 name.name = vdir->d_name;
 394
 395                 /* Make sure we skip '.' and '..', we already got those */
 396                 if (name.name[0] == '.' && (name.len == 1 ||
 397                     (name.name[1] == '.' && name.len == 2)))
 398                         vdir->d_fileno = name.len = 0;
 399
 400                 /* skip null entries */
 401                 if (vdir->d_fileno && name.len) {
 402                         ino = vdir->d_fileno;
 403                         type = CDT2DT(vdir->d_type);
 404                         if (!dir_emit(ctx, name.name, name.len, ino, type))
 405                                 break;
 406                 }
 407                 /* we'll always have progress because d_reclen is unsigned and
 408                  * we've already established it is non-zero. */
 409                 ctx->pos += vdir->d_reclen;
 410         }
 411 out:
 412         kfree(vdir);
 413         return 0;
 414 }
 415
 416 /* file operations for directories */
 417 static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
 418 {
 419         struct coda_file_info *cfi;
 420         struct file *host_file;
 421         int ret;
 422
 423         cfi = CODA_FTOC(coda_file);
 424         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 425         host_file = cfi->cfi_container;
 426
 427         if (host_file->f_op->iterate || host_file->f_op->iterate_shared) {
 428                 struct inode *host_inode = file_inode(host_file);
 429                 ret = -ENOENT;
 430                 if (!IS_DEADDIR(host_inode)) {
 431                         if (host_file->f_op->iterate_shared) {
 432                                 inode_lock_shared(host_inode);
 433                                 ret = host_file->f_op->iterate_shared(host_file, ctx);
 434                                 file_accessed(host_file);
 435                                 inode_unlock_shared(host_inode);
 436                         } else {
 437                                 inode_lock(host_inode);
 438                                 ret = host_file->f_op->iterate(host_file, ctx);
 439                                 file_accessed(host_file);
 440                                 inode_unlock(host_inode);
 441                         }
 442                 }
 443                 return ret;
 444         }
 445         /* Venus: we must read Venus dirents from a file */
 446         return coda_venus_readdir(coda_file, ctx);
 447 }
 448
 449 /* called when a cache lookup succeeds */
 450 static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
 451 {
 452         struct inode *inode;
 453         struct coda_inode_info *cii;
 454
 455         if (flags & LOOKUP_RCU)
 456                 return -ECHILD;
 457
 458         inode = d_inode(de);
 459         if (!inode || is_root_inode(inode))
 460                 goto out;
 461         if (is_bad_inode(inode))
 462                 goto bad;
 463
 464         cii = ITOC(d_inode(de));
 465         if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
 466                 goto out;
 467
 468         shrink_dcache_parent(de);
 469
 470         /* propagate for a flush */
 471         if (cii->c_flags & C_FLUSH)
 472                 coda_flag_inode_children(inode, C_FLUSH);
 473
 474         if (d_count(de) > 1)
 475                 /* pretend it's valid, but don't change the flags */
 476                 goto out;
 477
 478         /* clear the flags. */
 479         spin_lock(&cii->c_lock);
 480         cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 481         spin_unlock(&cii->c_lock);
 482 bad:
 483         return 0;
 484 out:
 485         return 1;
 486 }
 487
 488 /*
 489  * This is the callback from dput() when d_count is going to 0.
 490  * We use this to unhash dentries with bad inodes.
 491  */
 492 static int coda_dentry_delete(const struct dentry * dentry)
 493 {
 494         int flags;
 495
 496         if (d_really_is_negative(dentry))
 497                 return 0;
 498
 499         flags = (ITOC(d_inode(dentry))->c_flags) & C_PURGE;
 500         if (is_bad_inode(d_inode(dentry)) || flags) {
 501                 return 1;
 502         }
 503         return 0;
 504 }
 505
 506
 507
 508 /*
 509  * This is called when we want to check if the inode has
 510  * changed on the server.  Coda makes this easy since the
 511  * cache manager Venus issues a downcall to the kernel when this
 512  * happens
 513  */
 514 int coda_revalidate_inode(struct inode *inode)
 515 {
 516         struct coda_vattr attr;
 517         int error;
 518         int old_mode;
 519         ino_t old_ino;
 520         struct coda_inode_info *cii = ITOC(inode);
 521
 522         if (!cii->c_flags)
 523                 return 0;
 524
 525         if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
 526                 error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
 527                 if (error)
 528                         return -EIO;
 529
 530                 /* this inode may be lost if:
 531                    - it's ino changed
 532                    - type changes must be permitted for repair and
 533                    missing mount points.
 534                 */
 535                 old_mode = inode->i_mode;
 536                 old_ino = inode->i_ino;
 537                 coda_vattr_to_iattr(inode, &attr);
 538
 539                 if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
 540                         pr_warn("inode %ld, fid %s changed type!\n",
 541                                 inode->i_ino, coda_f2s(&(cii->c_fid)));
 542                 }
 543
 544                 /* the following can happen when a local fid is replaced
 545                    with a global one, here we lose and declare the inode bad */
 546                 if (inode->i_ino != old_ino)
 547                         return -EIO;
 548
 549                 coda_flag_inode_children(inode, C_FLUSH);
 550
 551                 spin_lock(&cii->c_lock);
 552                 cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 553                 spin_unlock(&cii->c_lock);
 554         }
 555         return 0;
 556 }
 557
 558 const struct dentry_operations coda_dentry_operations = {
 559         .d_revalidate   = coda_dentry_revalidate,
 560         .d_delete       = coda_dentry_delete,
 561 };
 562
 563 const struct inode_operations coda_dir_inode_operations = {
 564         .create         = coda_create,
 565         .lookup         = coda_lookup,
 566         .link           = coda_link,
 567         .unlink         = coda_unlink,
 568         .symlink        = coda_symlink,
 569         .mkdir          = coda_mkdir,
 570         .rmdir          = coda_rmdir,
 571         .mknod          = CODA_EIO_ERROR,
 572         .rename         = coda_rename,
 573         .permission     = coda_permission,
 574         .getattr        = coda_getattr,
 575         .setattr        = coda_setattr,
 576 };
 577
 578 const struct file_operations coda_dir_operations = {
 579         .llseek         = generic_file_llseek,
 580         .read           = generic_read_dir,
 581         .iterate        = coda_readdir,
 582         .open           = coda_open,
 583         .release        = coda_release,
 584         .fsync          = coda_fsync,
 585 };