root/fs/coda/dir.c

DEFINITIONS

1. coda_return_EIO
2. coda_lookup
3. coda_permission
4. coda_dir_update_mtime
5. coda_dir_inc_nlink
6. coda_dir_drop_nlink
7. coda_create
8. coda_mkdir
9. coda_link
10. coda_symlink
11. coda_unlink
12. coda_rmdir
13. coda_rename
14. CDT2DT
15. coda_venus_readdir
16. coda_readdir
17. coda_dentry_revalidate
18. coda_dentry_delete
19. coda_revalidate_inode

   1 // SPDX-License-Identifier: GPL-2.0
   2 
   3 /*
   4  * Directory operations for Coda filesystem
   5  * Original version: (C) 1996 P. Braam and M. Callahan
   6  * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
   7  * 
   8  * Carnegie Mellon encourages users to contribute improvements to
   9  * the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
  10  */
  11 
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/time.h>
  15 #include <linux/fs.h>
  16 #include <linux/slab.h>
  17 #include <linux/file.h>
  18 #include <linux/stat.h>
  19 #include <linux/errno.h>
  20 #include <linux/string.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/namei.h>
  23 #include <linux/uaccess.h>
  24 
  25 #include <linux/coda.h>
  26 #include "coda_psdev.h"
  27 #include "coda_linux.h"
  28 #include "coda_cache.h"
  29 
  30 #include "coda_int.h"
  31 
  32 /* same as fs/bad_inode.c */
  33 static int coda_return_EIO(void)
  34 {
  35         return -EIO;
  36 }
  37 #define CODA_EIO_ERROR ((void *) (coda_return_EIO))
  38 
  39 /* inode operations for directories */
  40 /* access routines: lookup, readlink, permission */
  41 static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
  42 {
  43         struct super_block *sb = dir->i_sb;
  44         const char *name = entry->d_name.name;
  45         size_t length = entry->d_name.len;
  46         struct inode *inode;
  47         int type = 0;
  48 
  49         if (length > CODA_MAXNAMLEN) {
  50                 pr_err("name too long: lookup, %s %zu\n",
  51                        coda_i2s(dir), length);
  52                 return ERR_PTR(-ENAMETOOLONG);
  53         }
  54 
  55         /* control object, create inode on the fly */
  56         if (is_root_inode(dir) && coda_iscontrol(name, length)) {
  57                 inode = coda_cnode_makectl(sb);
  58                 type = CODA_NOCACHE;
  59         } else {
  60                 struct CodaFid fid = { { 0, } };
  61                 int error = venus_lookup(sb, coda_i2f(dir), name, length,
  62                                      &type, &fid);
  63                 inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
  64         }
  65 
  66         if (!IS_ERR(inode) && (type & CODA_NOCACHE))
  67                 coda_flag_inode(inode, C_VATTR | C_PURGE);
  68 
  69         if (inode == ERR_PTR(-ENOENT))
  70                 inode = NULL;
  71 
  72         return d_splice_alias(inode, entry);
  73 }
  74 
  75 
  76 int coda_permission(struct inode *inode, int mask)
  77 {
  78         int error;
  79 
  80         if (mask & MAY_NOT_BLOCK)
  81                 return -ECHILD;
  82 
  83         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
  84  
  85         if (!mask)
  86                 return 0;
  87 
  88         if ((mask & MAY_EXEC) && !execute_ok(inode))
  89                 return -EACCES;
  90 
  91         if (coda_cache_check(inode, mask))
  92                 return 0;
  93 
  94         error = venus_access(inode->i_sb, coda_i2f(inode), mask);
  95     
  96         if (!error)
  97                 coda_cache_enter(inode, mask);
  98 
  99         return error;
 100 }
 101 
 102 
 103 static inline void coda_dir_update_mtime(struct inode *dir)
 104 {
 105 #ifdef REQUERY_VENUS_FOR_MTIME
 106         /* invalidate the directory cnode's attributes so we refetch the
 107          * attributes from venus next time the inode is referenced */
 108         coda_flag_inode(dir, C_VATTR);
 109 #else
 110         /* optimistically we can also act as if our nose bleeds. The
 111          * granularity of the mtime is coarse anyways so we might actually be
 112          * right most of the time. Note: we only do this for directories. */
 113         dir->i_mtime = dir->i_ctime = current_time(dir);
 114 #endif
 115 }
 116 
 117 /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
 118  * trick to fool GNU find's optimizations. If we can't be sure of the link
 119  * (because of volume mount points) we set i_nlink to 1 which forces find
 120  * to consider every child as a possible directory. We should also never
 121  * see an increment or decrement for deleted directories where i_nlink == 0 */
 122 static inline void coda_dir_inc_nlink(struct inode *dir)
 123 {
 124         if (dir->i_nlink >= 2)
 125                 inc_nlink(dir);
 126 }
 127 
 128 static inline void coda_dir_drop_nlink(struct inode *dir)
 129 {
 130         if (dir->i_nlink > 2)
 131                 drop_nlink(dir);
 132 }
 133 
 134 /* creation routines: create, mknod, mkdir, link, symlink */
 135 static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
 136 {
 137         int error;
 138         const char *name=de->d_name.name;
 139         int length=de->d_name.len;
 140         struct inode *inode;
 141         struct CodaFid newfid;
 142         struct coda_vattr attrs;
 143 
 144         if (is_root_inode(dir) && coda_iscontrol(name, length))
 145                 return -EPERM;
 146 
 147         error = venus_create(dir->i_sb, coda_i2f(dir), name, length, 
 148                                 0, mode, &newfid, &attrs);
 149         if (error)
 150                 goto err_out;
 151 
 152         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 153         if (IS_ERR(inode)) {
 154                 error = PTR_ERR(inode);
 155                 goto err_out;
 156         }
 157 
 158         /* invalidate the directory cnode's attributes */
 159         coda_dir_update_mtime(dir);
 160         d_instantiate(de, inode);
 161         return 0;
 162 err_out:
 163         d_drop(de);
 164         return error;
 165 }
 166 
 167 static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
 168 {
 169         struct inode *inode;
 170         struct coda_vattr attrs;
 171         const char *name = de->d_name.name;
 172         int len = de->d_name.len;
 173         int error;
 174         struct CodaFid newfid;
 175 
 176         if (is_root_inode(dir) && coda_iscontrol(name, len))
 177                 return -EPERM;
 178 
 179         attrs.va_mode = mode;
 180         error = venus_mkdir(dir->i_sb, coda_i2f(dir), 
 181                                name, len, &newfid, &attrs);
 182         if (error)
 183                 goto err_out;
 184          
 185         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 186         if (IS_ERR(inode)) {
 187                 error = PTR_ERR(inode);
 188                 goto err_out;
 189         }
 190 
 191         /* invalidate the directory cnode's attributes */
 192         coda_dir_inc_nlink(dir);
 193         coda_dir_update_mtime(dir);
 194         d_instantiate(de, inode);
 195         return 0;
 196 err_out:
 197         d_drop(de);
 198         return error;
 199 }
 200 
 201 /* try to make de an entry in dir_inodde linked to source_de */ 
 202 static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
 203           struct dentry *de)
 204 {
 205         struct inode *inode = d_inode(source_de);
 206         const char * name = de->d_name.name;
 207         int len = de->d_name.len;
 208         int error;
 209 
 210         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 211                 return -EPERM;
 212 
 213         error = venus_link(dir_inode->i_sb, coda_i2f(inode),
 214                            coda_i2f(dir_inode), (const char *)name, len);
 215         if (error) {
 216                 d_drop(de);
 217                 return error;
 218         }
 219 
 220         coda_dir_update_mtime(dir_inode);
 221         ihold(inode);
 222         d_instantiate(de, inode);
 223         inc_nlink(inode);
 224         return 0;
 225 }
 226 
 227 
 228 static int coda_symlink(struct inode *dir_inode, struct dentry *de,
 229                         const char *symname)
 230 {
 231         const char *name = de->d_name.name;
 232         int len = de->d_name.len;
 233         int symlen;
 234         int error;
 235 
 236         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 237                 return -EPERM;
 238 
 239         symlen = strlen(symname);
 240         if (symlen > CODA_MAXPATHLEN)
 241                 return -ENAMETOOLONG;
 242 
 243         /*
 244          * This entry is now negative. Since we do not create
 245          * an inode for the entry we have to drop it.
 246          */
 247         d_drop(de);
 248         error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
 249                               symname, symlen);
 250 
 251         /* mtime is no good anymore */
 252         if (!error)
 253                 coda_dir_update_mtime(dir_inode);
 254 
 255         return error;
 256 }
 257 
 258 /* destruction routines: unlink, rmdir */
 259 static int coda_unlink(struct inode *dir, struct dentry *de)
 260 {
 261         int error;
 262         const char *name = de->d_name.name;
 263         int len = de->d_name.len;
 264 
 265         error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
 266         if (error)
 267                 return error;
 268 
 269         coda_dir_update_mtime(dir);
 270         drop_nlink(d_inode(de));
 271         return 0;
 272 }
 273 
 274 static int coda_rmdir(struct inode *dir, struct dentry *de)
 275 {
 276         const char *name = de->d_name.name;
 277         int len = de->d_name.len;
 278         int error;
 279 
 280         error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
 281         if (!error) {
 282                 /* VFS may delete the child */
 283                 if (d_really_is_positive(de))
 284                         clear_nlink(d_inode(de));
 285 
 286                 /* fix the link count of the parent */
 287                 coda_dir_drop_nlink(dir);
 288                 coda_dir_update_mtime(dir);
 289         }
 290         return error;
 291 }
 292 
 293 /* rename */
 294 static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 295                        struct inode *new_dir, struct dentry *new_dentry,
 296                        unsigned int flags)
 297 {
 298         const char *old_name = old_dentry->d_name.name;
 299         const char *new_name = new_dentry->d_name.name;
 300         int old_length = old_dentry->d_name.len;
 301         int new_length = new_dentry->d_name.len;
 302         int error;
 303 
 304         if (flags)
 305                 return -EINVAL;
 306 
 307         error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
 308                              coda_i2f(new_dir), old_length, new_length,
 309                              (const char *) old_name, (const char *)new_name);
 310         if (!error) {
 311                 if (d_really_is_positive(new_dentry)) {
 312                         if (d_is_dir(new_dentry)) {
 313                                 coda_dir_drop_nlink(old_dir);
 314                                 coda_dir_inc_nlink(new_dir);
 315                         }
 316                         coda_dir_update_mtime(old_dir);
 317                         coda_dir_update_mtime(new_dir);
 318                         coda_flag_inode(d_inode(new_dentry), C_VATTR);
 319                 } else {
 320                         coda_flag_inode(old_dir, C_VATTR);
 321                         coda_flag_inode(new_dir, C_VATTR);
 322                 }
 323         }
 324         return error;
 325 }
 326 
 327 static inline unsigned int CDT2DT(unsigned char cdt)
 328 {
 329         unsigned int dt;
 330 
 331         switch(cdt) {
 332         case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
 333         case CDT_FIFO:    dt = DT_FIFO;    break;
 334         case CDT_CHR:     dt = DT_CHR;     break;
 335         case CDT_DIR:     dt = DT_DIR;     break;
 336         case CDT_BLK:     dt = DT_BLK;     break;
 337         case CDT_REG:     dt = DT_REG;     break;
 338         case CDT_LNK:     dt = DT_LNK;     break;
 339         case CDT_SOCK:    dt = DT_SOCK;    break;
 340         case CDT_WHT:     dt = DT_WHT;     break;
 341         default:          dt = DT_UNKNOWN; break;
 342         }
 343         return dt;
 344 }
 345 
 346 /* support routines */
 347 static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
 348 {
 349         struct coda_file_info *cfi;
 350         struct coda_inode_info *cii;
 351         struct file *host_file;
 352         struct venus_dirent *vdir;
 353         unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
 354         unsigned int type;
 355         struct qstr name;
 356         ino_t ino;
 357         int ret;
 358 
 359         cfi = coda_ftoc(coda_file);
 360         host_file = cfi->cfi_container;
 361 
 362         cii = ITOC(file_inode(coda_file));
 363 
 364         vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
 365         if (!vdir) return -ENOMEM;
 366 
 367         if (!dir_emit_dots(coda_file, ctx))
 368                 goto out;
 369 
 370         while (1) {
 371                 loff_t pos = ctx->pos - 2;
 372 
 373                 /* read entries from the directory file */
 374                 ret = kernel_read(host_file, vdir, sizeof(*vdir), &pos);
 375                 if (ret < 0) {
 376                         pr_err("%s: read dir %s failed %d\n",
 377                                __func__, coda_f2s(&cii->c_fid), ret);
 378                         break;
 379                 }
 380                 if (ret == 0) break; /* end of directory file reached */
 381 
 382                 /* catch truncated reads */
 383                 if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
 384                         pr_err("%s: short read on %s\n",
 385                                __func__, coda_f2s(&cii->c_fid));
 386                         ret = -EBADF;
 387                         break;
 388                 }
 389                 /* validate whether the directory file actually makes sense */
 390                 if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
 391                         pr_err("%s: invalid dir %s\n",
 392                                __func__, coda_f2s(&cii->c_fid));
 393                         ret = -EBADF;
 394                         break;
 395                 }
 396 
 397                 name.len = vdir->d_namlen;
 398                 name.name = vdir->d_name;
 399 
 400                 /* Make sure we skip '.' and '..', we already got those */
 401                 if (name.name[0] == '.' && (name.len == 1 ||
 402                     (name.name[1] == '.' && name.len == 2)))
 403                         vdir->d_fileno = name.len = 0;
 404 
 405                 /* skip null entries */
 406                 if (vdir->d_fileno && name.len) {
 407                         ino = vdir->d_fileno;
 408                         type = CDT2DT(vdir->d_type);
 409                         if (!dir_emit(ctx, name.name, name.len, ino, type))
 410                                 break;
 411                 }
 412                 /* we'll always have progress because d_reclen is unsigned and
 413                  * we've already established it is non-zero. */
 414                 ctx->pos += vdir->d_reclen;
 415         }
 416 out:
 417         kfree(vdir);
 418         return 0;
 419 }
 420 
 421 /* file operations for directories */
 422 static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
 423 {
 424         struct coda_file_info *cfi;
 425         struct file *host_file;
 426         int ret;
 427 
 428         cfi = coda_ftoc(coda_file);
 429         host_file = cfi->cfi_container;
 430 
 431         if (host_file->f_op->iterate || host_file->f_op->iterate_shared) {
 432                 struct inode *host_inode = file_inode(host_file);
 433                 ret = -ENOENT;
 434                 if (!IS_DEADDIR(host_inode)) {
 435                         if (host_file->f_op->iterate_shared) {
 436                                 inode_lock_shared(host_inode);
 437                                 ret = host_file->f_op->iterate_shared(host_file, ctx);
 438                                 file_accessed(host_file);
 439                                 inode_unlock_shared(host_inode);
 440                         } else {
 441                                 inode_lock(host_inode);
 442                                 ret = host_file->f_op->iterate(host_file, ctx);
 443                                 file_accessed(host_file);
 444                                 inode_unlock(host_inode);
 445                         }
 446                 }
 447                 return ret;
 448         }
 449         /* Venus: we must read Venus dirents from a file */
 450         return coda_venus_readdir(coda_file, ctx);
 451 }
 452 
 453 /* called when a cache lookup succeeds */
 454 static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
 455 {
 456         struct inode *inode;
 457         struct coda_inode_info *cii;
 458 
 459         if (flags & LOOKUP_RCU)
 460                 return -ECHILD;
 461 
 462         inode = d_inode(de);
 463         if (!inode || is_root_inode(inode))
 464                 goto out;
 465         if (is_bad_inode(inode))
 466                 goto bad;
 467 
 468         cii = ITOC(d_inode(de));
 469         if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
 470                 goto out;
 471 
 472         shrink_dcache_parent(de);
 473 
 474         /* propagate for a flush */
 475         if (cii->c_flags & C_FLUSH) 
 476                 coda_flag_inode_children(inode, C_FLUSH);
 477 
 478         if (d_count(de) > 1)
 479                 /* pretend it's valid, but don't change the flags */
 480                 goto out;
 481 
 482         /* clear the flags. */
 483         spin_lock(&cii->c_lock);
 484         cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 485         spin_unlock(&cii->c_lock);
 486 bad:
 487         return 0;
 488 out:
 489         return 1;
 490 }
 491 
 492 /*
 493  * This is the callback from dput() when d_count is going to 0.
 494  * We use this to unhash dentries with bad inodes.
 495  */
 496 static int coda_dentry_delete(const struct dentry * dentry)
 497 {
 498         int flags;
 499 
 500         if (d_really_is_negative(dentry)) 
 501                 return 0;
 502 
 503         flags = (ITOC(d_inode(dentry))->c_flags) & C_PURGE;
 504         if (is_bad_inode(d_inode(dentry)) || flags) {
 505                 return 1;
 506         }
 507         return 0;
 508 }
 509 
 510 
 511 
 512 /*
 513  * This is called when we want to check if the inode has
 514  * changed on the server.  Coda makes this easy since the
 515  * cache manager Venus issues a downcall to the kernel when this 
 516  * happens 
 517  */
 518 int coda_revalidate_inode(struct inode *inode)
 519 {
 520         struct coda_vattr attr;
 521         int error;
 522         int old_mode;
 523         ino_t old_ino;
 524         struct coda_inode_info *cii = ITOC(inode);
 525 
 526         if (!cii->c_flags)
 527                 return 0;
 528 
 529         if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
 530                 error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
 531                 if (error)
 532                         return -EIO;
 533 
 534                 /* this inode may be lost if:
 535                    - it's ino changed 
 536                    - type changes must be permitted for repair and
 537                    missing mount points.
 538                 */
 539                 old_mode = inode->i_mode;
 540                 old_ino = inode->i_ino;
 541                 coda_vattr_to_iattr(inode, &attr);
 542 
 543                 if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
 544                         pr_warn("inode %ld, fid %s changed type!\n",
 545                                 inode->i_ino, coda_f2s(&(cii->c_fid)));
 546                 }
 547 
 548                 /* the following can happen when a local fid is replaced 
 549                    with a global one, here we lose and declare the inode bad */
 550                 if (inode->i_ino != old_ino)
 551                         return -EIO;
 552                 
 553                 coda_flag_inode_children(inode, C_FLUSH);
 554 
 555                 spin_lock(&cii->c_lock);
 556                 cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 557                 spin_unlock(&cii->c_lock);
 558         }
 559         return 0;
 560 }
 561 
 562 const struct dentry_operations coda_dentry_operations = {
 563         .d_revalidate   = coda_dentry_revalidate,
 564         .d_delete       = coda_dentry_delete,
 565 };
 566 
 567 const struct inode_operations coda_dir_inode_operations = {
 568         .create         = coda_create,
 569         .lookup         = coda_lookup,
 570         .link           = coda_link,
 571         .unlink         = coda_unlink,
 572         .symlink        = coda_symlink,
 573         .mkdir          = coda_mkdir,
 574         .rmdir          = coda_rmdir,
 575         .mknod          = CODA_EIO_ERROR,
 576         .rename         = coda_rename,
 577         .permission     = coda_permission,
 578         .getattr        = coda_getattr,
 579         .setattr        = coda_setattr,
 580 };
 581 
 582 const struct file_operations coda_dir_operations = {
 583         .llseek         = generic_file_llseek,
 584         .read           = generic_read_dir,
 585         .iterate        = coda_readdir,
 586         .open           = coda_open,
 587         .release        = coda_release,
 588         .fsync          = coda_fsync,
 589 };