fs/coda/dir.c

   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 user_namespace *mnt_userns, struct inode *inode,
  77                     int mask)
  78 {
  79         int error;
  80
  81         if (mask & MAY_NOT_BLOCK)
  82                 return -ECHILD;
  83
  84         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
  85
  86         if (!mask)
  87                 return 0;
  88
  89         if ((mask & MAY_EXEC) && !execute_ok(inode))
  90                 return -EACCES;
  91
  92         if (coda_cache_check(inode, mask))
  93                 return 0;
  94
  95         error = venus_access(inode->i_sb, coda_i2f(inode), mask);
  96
  97         if (!error)
  98                 coda_cache_enter(inode, mask);
  99
 100         return error;
 101 }
 102
 103
 104 static inline void coda_dir_update_mtime(struct inode *dir)
 105 {
 106 #ifdef REQUERY_VENUS_FOR_MTIME
 107         /* invalidate the directory cnode's attributes so we refetch the
 108          * attributes from venus next time the inode is referenced */
 109         coda_flag_inode(dir, C_VATTR);
 110 #else
 111         /* optimistically we can also act as if our nose bleeds. The
 112          * granularity of the mtime is coarse anyways so we might actually be
 113          * right most of the time. Note: we only do this for directories. */
 114         dir->i_mtime = dir->i_ctime = current_time(dir);
 115 #endif
 116 }
 117
 118 /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
 119  * trick to fool GNU find's optimizations. If we can't be sure of the link
 120  * (because of volume mount points) we set i_nlink to 1 which forces find
 121  * to consider every child as a possible directory. We should also never
 122  * see an increment or decrement for deleted directories where i_nlink == 0 */
 123 static inline void coda_dir_inc_nlink(struct inode *dir)
 124 {
 125         if (dir->i_nlink >= 2)
 126                 inc_nlink(dir);
 127 }
 128
 129 static inline void coda_dir_drop_nlink(struct inode *dir)
 130 {
 131         if (dir->i_nlink > 2)
 132                 drop_nlink(dir);
 133 }
 134
 135 /* creation routines: create, mknod, mkdir, link, symlink */
 136 static int coda_create(struct user_namespace *mnt_userns, struct inode *dir,
 137                        struct dentry *de, umode_t mode, bool excl)
 138 {
 139         int error;
 140         const char *name=de->d_name.name;
 141         int length=de->d_name.len;
 142         struct inode *inode;
 143         struct CodaFid newfid;
 144         struct coda_vattr attrs;
 145
 146         if (is_root_inode(dir) && coda_iscontrol(name, length))
 147                 return -EPERM;
 148
 149         error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
 150                                 0, mode, &newfid, &attrs);
 151         if (error)
 152                 goto err_out;
 153
 154         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 155         if (IS_ERR(inode)) {
 156                 error = PTR_ERR(inode);
 157                 goto err_out;
 158         }
 159
 160         /* invalidate the directory cnode's attributes */
 161         coda_dir_update_mtime(dir);
 162         d_instantiate(de, inode);
 163         return 0;
 164 err_out:
 165         d_drop(de);
 166         return error;
 167 }
 168
 169 static int coda_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 170                       struct dentry *de, umode_t mode)
 171 {
 172         struct inode *inode;
 173         struct coda_vattr attrs;
 174         const char *name = de->d_name.name;
 175         int len = de->d_name.len;
 176         int error;
 177         struct CodaFid newfid;
 178
 179         if (is_root_inode(dir) && coda_iscontrol(name, len))
 180                 return -EPERM;
 181
 182         attrs.va_mode = mode;
 183         error = venus_mkdir(dir->i_sb, coda_i2f(dir),
 184                                name, len, &newfid, &attrs);
 185         if (error)
 186                 goto err_out;
 187
 188         inode = coda_iget(dir->i_sb, &newfid, &attrs);
 189         if (IS_ERR(inode)) {
 190                 error = PTR_ERR(inode);
 191                 goto err_out;
 192         }
 193
 194         /* invalidate the directory cnode's attributes */
 195         coda_dir_inc_nlink(dir);
 196         coda_dir_update_mtime(dir);
 197         d_instantiate(de, inode);
 198         return 0;
 199 err_out:
 200         d_drop(de);
 201         return error;
 202 }
 203
 204 /* try to make de an entry in dir_inodde linked to source_de */
 205 static int coda_link(struct dentry *source_de, struct inode *dir_inode,
 206           struct dentry *de)
 207 {
 208         struct inode *inode = d_inode(source_de);
 209         const char * name = de->d_name.name;
 210         int len = de->d_name.len;
 211         int error;
 212
 213         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 214                 return -EPERM;
 215
 216         error = venus_link(dir_inode->i_sb, coda_i2f(inode),
 217                            coda_i2f(dir_inode), (const char *)name, len);
 218         if (error) {
 219                 d_drop(de);
 220                 return error;
 221         }
 222
 223         coda_dir_update_mtime(dir_inode);
 224         ihold(inode);
 225         d_instantiate(de, inode);
 226         inc_nlink(inode);
 227         return 0;
 228 }
 229
 230
 231 static int coda_symlink(struct user_namespace *mnt_userns,
 232                         struct inode *dir_inode, struct dentry *de,
 233                         const char *symname)
 234 {
 235         const char *name = de->d_name.name;
 236         int len = de->d_name.len;
 237         int symlen;
 238         int error;
 239
 240         if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
 241                 return -EPERM;
 242
 243         symlen = strlen(symname);
 244         if (symlen > CODA_MAXPATHLEN)
 245                 return -ENAMETOOLONG;
 246
 247         /*
 248          * This entry is now negative. Since we do not create
 249          * an inode for the entry we have to drop it.
 250          */
 251         d_drop(de);
 252         error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
 253                               symname, symlen);
 254
 255         /* mtime is no good anymore */
 256         if (!error)
 257                 coda_dir_update_mtime(dir_inode);
 258
 259         return error;
 260 }
 261
 262 /* destruction routines: unlink, rmdir */
 263 static int coda_unlink(struct inode *dir, struct dentry *de)
 264 {
 265         int error;
 266         const char *name = de->d_name.name;
 267         int len = de->d_name.len;
 268
 269         error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
 270         if (error)
 271                 return error;
 272
 273         coda_dir_update_mtime(dir);
 274         drop_nlink(d_inode(de));
 275         return 0;
 276 }
 277
 278 static int coda_rmdir(struct inode *dir, struct dentry *de)
 279 {
 280         const char *name = de->d_name.name;
 281         int len = de->d_name.len;
 282         int error;
 283
 284         error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
 285         if (!error) {
 286                 /* VFS may delete the child */
 287                 if (d_really_is_positive(de))
 288                         clear_nlink(d_inode(de));
 289
 290                 /* fix the link count of the parent */
 291                 coda_dir_drop_nlink(dir);
 292                 coda_dir_update_mtime(dir);
 293         }
 294         return error;
 295 }
 296
 297 /* rename */
 298 static int coda_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 299                        struct dentry *old_dentry, struct inode *new_dir,
 300                        struct dentry *new_dentry, unsigned int flags)
 301 {
 302         const char *old_name = old_dentry->d_name.name;
 303         const char *new_name = new_dentry->d_name.name;
 304         int old_length = old_dentry->d_name.len;
 305         int new_length = new_dentry->d_name.len;
 306         int error;
 307
 308         if (flags)
 309                 return -EINVAL;
 310
 311         error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
 312                              coda_i2f(new_dir), old_length, new_length,
 313                              (const char *) old_name, (const char *)new_name);
 314         if (!error) {
 315                 if (d_really_is_positive(new_dentry)) {
 316                         if (d_is_dir(new_dentry)) {
 317                                 coda_dir_drop_nlink(old_dir);
 318                                 coda_dir_inc_nlink(new_dir);
 319                         }
 320                         coda_flag_inode(d_inode(new_dentry), C_VATTR);
 321                 }
 322                 coda_dir_update_mtime(old_dir);
 323                 coda_dir_update_mtime(new_dir);
 324         }
 325         return error;
 326 }
 327
 328 static inline unsigned int CDT2DT(unsigned char cdt)
 329 {
 330         unsigned int dt;
 331
 332         switch(cdt) {
 333         case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
 334         case CDT_FIFO:    dt = DT_FIFO;    break;
 335         case CDT_CHR:     dt = DT_CHR;     break;
 336         case CDT_DIR:     dt = DT_DIR;     break;
 337         case CDT_BLK:     dt = DT_BLK;     break;
 338         case CDT_REG:     dt = DT_REG;     break;
 339         case CDT_LNK:     dt = DT_LNK;     break;
 340         case CDT_SOCK:    dt = DT_SOCK;    break;
 341         case CDT_WHT:     dt = DT_WHT;     break;
 342         default:          dt = DT_UNKNOWN; break;
 343         }
 344         return dt;
 345 }
 346
 347 /* support routines */
 348 static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
 349 {
 350         struct coda_file_info *cfi;
 351         struct coda_inode_info *cii;
 352         struct file *host_file;
 353         struct venus_dirent *vdir;
 354         unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
 355         unsigned int type;
 356         struct qstr name;
 357         ino_t ino;
 358         int ret;
 359
 360         cfi = coda_ftoc(coda_file);
 361         host_file = cfi->cfi_container;
 362
 363         cii = ITOC(file_inode(coda_file));
 364
 365         vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
 366         if (!vdir) return -ENOMEM;
 367
 368         if (!dir_emit_dots(coda_file, ctx))
 369                 goto out;
 370
 371         while (1) {
 372                 loff_t pos = ctx->pos - 2;
 373
 374                 /* read entries from the directory file */
 375                 ret = kernel_read(host_file, vdir, sizeof(*vdir), &pos);
 376                 if (ret < 0) {
 377                         pr_err("%s: read dir %s failed %d\n",
 378                                __func__, coda_f2s(&cii->c_fid), ret);
 379                         break;
 380                 }
 381                 if (ret == 0) break; /* end of directory file reached */
 382
 383                 /* catch truncated reads */
 384                 if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
 385                         pr_err("%s: short read on %s\n",
 386                                __func__, coda_f2s(&cii->c_fid));
 387                         ret = -EBADF;
 388                         break;
 389                 }
 390                 /* validate whether the directory file actually makes sense */
 391                 if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
 392                         pr_err("%s: invalid dir %s\n",
 393                                __func__, coda_f2s(&cii->c_fid));
 394                         ret = -EBADF;
 395                         break;
 396                 }
 397
 398                 name.len = vdir->d_namlen;
 399                 name.name = vdir->d_name;
 400
 401                 /* Make sure we skip '.' and '..', we already got those */
 402                 if (name.name[0] == '.' && (name.len == 1 ||
 403                     (name.name[1] == '.' && name.len == 2)))
 404                         vdir->d_fileno = name.len = 0;
 405
 406                 /* skip null entries */
 407                 if (vdir->d_fileno && name.len) {
 408                         ino = vdir->d_fileno;
 409                         type = CDT2DT(vdir->d_type);
 410                         if (!dir_emit(ctx, name.name, name.len, ino, type))
 411                                 break;
 412                 }
 413                 /* we'll always have progress because d_reclen is unsigned and
 414                  * we've already established it is non-zero. */
 415                 ctx->pos += vdir->d_reclen;
 416         }
 417 out:
 418         kfree(vdir);
 419         return 0;
 420 }
 421
 422 /* file operations for directories */
 423 static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
 424 {
 425         struct coda_file_info *cfi;
 426         struct file *host_file;
 427         int ret;
 428
 429         cfi = coda_ftoc(coda_file);
 430         host_file = cfi->cfi_container;
 431
 432         if (host_file->f_op->iterate || host_file->f_op->iterate_shared) {
 433                 struct inode *host_inode = file_inode(host_file);
 434                 ret = -ENOENT;
 435                 if (!IS_DEADDIR(host_inode)) {
 436                         if (host_file->f_op->iterate_shared) {
 437                                 inode_lock_shared(host_inode);
 438                                 ret = host_file->f_op->iterate_shared(host_file, ctx);
 439                                 file_accessed(host_file);
 440                                 inode_unlock_shared(host_inode);
 441                         } else {
 442                                 inode_lock(host_inode);
 443                                 ret = host_file->f_op->iterate(host_file, ctx);
 444                                 file_accessed(host_file);
 445                                 inode_unlock(host_inode);
 446                         }
 447                 }
 448                 return ret;
 449         }
 450         /* Venus: we must read Venus dirents from a file */
 451         return coda_venus_readdir(coda_file, ctx);
 452 }
 453
 454 /* called when a cache lookup succeeds */
 455 static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
 456 {
 457         struct inode *inode;
 458         struct coda_inode_info *cii;
 459
 460         if (flags & LOOKUP_RCU)
 461                 return -ECHILD;
 462
 463         inode = d_inode(de);
 464         if (!inode || is_root_inode(inode))
 465                 goto out;
 466         if (is_bad_inode(inode))
 467                 goto bad;
 468
 469         cii = ITOC(d_inode(de));
 470         if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
 471                 goto out;
 472
 473         shrink_dcache_parent(de);
 474
 475         /* propagate for a flush */
 476         if (cii->c_flags & C_FLUSH)
 477                 coda_flag_inode_children(inode, C_FLUSH);
 478
 479         if (d_count(de) > 1)
 480                 /* pretend it's valid, but don't change the flags */
 481                 goto out;
 482
 483         /* clear the flags. */
 484         spin_lock(&cii->c_lock);
 485         cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 486         spin_unlock(&cii->c_lock);
 487 bad:
 488         return 0;
 489 out:
 490         return 1;
 491 }
 492
 493 /*
 494  * This is the callback from dput() when d_count is going to 0.
 495  * We use this to unhash dentries with bad inodes.
 496  */
 497 static int coda_dentry_delete(const struct dentry * dentry)
 498 {
 499         struct inode *inode;
 500         struct coda_inode_info *cii;
 501
 502         if (d_really_is_negative(dentry))
 503                 return 0;
 504
 505         inode = d_inode(dentry);
 506         if (!inode || is_bad_inode(inode))
 507                 return 1;
 508
 509         cii = ITOC(inode);
 510         if (cii->c_flags & C_PURGE)
 511                 return 1;
 512
 513         return 0;
 514 }
 515
 516
 517
 518 /*
 519  * This is called when we want to check if the inode has
 520  * changed on the server.  Coda makes this easy since the
 521  * cache manager Venus issues a downcall to the kernel when this
 522  * happens
 523  */
 524 int coda_revalidate_inode(struct inode *inode)
 525 {
 526         struct coda_vattr attr;
 527         int error;
 528         int old_mode;
 529         ino_t old_ino;
 530         struct coda_inode_info *cii = ITOC(inode);
 531
 532         if (!cii->c_flags)
 533                 return 0;
 534
 535         if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
 536                 error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
 537                 if (error)
 538                         return -EIO;
 539
 540                 /* this inode may be lost if:
 541                    - it's ino changed
 542                    - type changes must be permitted for repair and
 543                    missing mount points.
 544                 */
 545                 old_mode = inode->i_mode;
 546                 old_ino = inode->i_ino;
 547                 coda_vattr_to_iattr(inode, &attr);
 548
 549                 if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
 550                         pr_warn("inode %ld, fid %s changed type!\n",
 551                                 inode->i_ino, coda_f2s(&(cii->c_fid)));
 552                 }
 553
 554                 /* the following can happen when a local fid is replaced
 555                    with a global one, here we lose and declare the inode bad */
 556                 if (inode->i_ino != old_ino)
 557                         return -EIO;
 558
 559                 coda_flag_inode_children(inode, C_FLUSH);
 560
 561                 spin_lock(&cii->c_lock);
 562                 cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 563                 spin_unlock(&cii->c_lock);
 564         }
 565         return 0;
 566 }
 567
 568 const struct dentry_operations coda_dentry_operations = {
 569         .d_revalidate   = coda_dentry_revalidate,
 570         .d_delete       = coda_dentry_delete,
 571 };
 572
 573 const struct inode_operations coda_dir_inode_operations = {
 574         .create         = coda_create,
 575         .lookup         = coda_lookup,
 576         .link           = coda_link,
 577         .unlink         = coda_unlink,
 578         .symlink        = coda_symlink,
 579         .mkdir          = coda_mkdir,
 580         .rmdir          = coda_rmdir,
 581         .mknod          = CODA_EIO_ERROR,
 582         .rename         = coda_rename,
 583         .permission     = coda_permission,
 584         .getattr        = coda_getattr,
 585         .setattr        = coda_setattr,
 586 };
 587
 588 const struct file_operations coda_dir_operations = {
 589         .llseek         = generic_file_llseek,
 590         .read           = generic_read_dir,
 591         .iterate        = coda_readdir,
 592         .open           = coda_open,
 593         .release        = coda_release,
 594         .fsync          = coda_fsync,
 595 };