linux/fs/coda/dir.c
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   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 */
  32static 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 */
  40static 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
  75int 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
 102static 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 */
 121static inline void coda_dir_inc_nlink(struct inode *dir)
 122{
 123        if (dir->i_nlink >= 2)
 124                inc_nlink(dir);
 125}
 126
 127static 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 */
 134static 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;
 161err_out:
 162        d_drop(de);
 163        return error;
 164}
 165
 166static 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;
 195err_out:
 196        d_drop(de);
 197        return error;
 198}
 199
 200/* try to make de an entry in dir_inodde linked to source_de */ 
 201static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
 202          struct dentry *de)
 203{
 204        struct inode *inode = source_de->d_inode;
 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
 227static 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 */
 258static 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(de->d_inode);
 270        return 0;
 271}
 272
 273static 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 (de->d_inode)
 283                        clear_nlink(de->d_inode);
 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 */
 293static 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 (new_dentry->d_inode) {
 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(new_dentry->d_inode, 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
 322static 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 */
 342static 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        }
 411out:
 412        kfree(vdir);
 413        return 0;
 414}
 415
 416/* file operations for directories */
 417static 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) {
 428                struct inode *host_inode = file_inode(host_file);
 429
 430                mutex_lock(&host_inode->i_mutex);
 431                ret = -ENOENT;
 432                if (!IS_DEADDIR(host_inode)) {
 433                        ret = host_file->f_op->iterate(host_file, ctx);
 434                        file_accessed(host_file);
 435                }
 436                mutex_unlock(&host_inode->i_mutex);
 437                return ret;
 438        }
 439        /* Venus: we must read Venus dirents from a file */
 440        return coda_venus_readdir(coda_file, ctx);
 441}
 442
 443/* called when a cache lookup succeeds */
 444static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
 445{
 446        struct inode *inode;
 447        struct coda_inode_info *cii;
 448
 449        if (flags & LOOKUP_RCU)
 450                return -ECHILD;
 451
 452        inode = de->d_inode;
 453        if (!inode || is_root_inode(inode))
 454                goto out;
 455        if (is_bad_inode(inode))
 456                goto bad;
 457
 458        cii = ITOC(de->d_inode);
 459        if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
 460                goto out;
 461
 462        shrink_dcache_parent(de);
 463
 464        /* propagate for a flush */
 465        if (cii->c_flags & C_FLUSH) 
 466                coda_flag_inode_children(inode, C_FLUSH);
 467
 468        if (d_count(de) > 1)
 469                /* pretend it's valid, but don't change the flags */
 470                goto out;
 471
 472        /* clear the flags. */
 473        spin_lock(&cii->c_lock);
 474        cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 475        spin_unlock(&cii->c_lock);
 476bad:
 477        return 0;
 478out:
 479        return 1;
 480}
 481
 482/*
 483 * This is the callback from dput() when d_count is going to 0.
 484 * We use this to unhash dentries with bad inodes.
 485 */
 486static int coda_dentry_delete(const struct dentry * dentry)
 487{
 488        int flags;
 489
 490        if (!dentry->d_inode) 
 491                return 0;
 492
 493        flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
 494        if (is_bad_inode(dentry->d_inode) || flags) {
 495                return 1;
 496        }
 497        return 0;
 498}
 499
 500
 501
 502/*
 503 * This is called when we want to check if the inode has
 504 * changed on the server.  Coda makes this easy since the
 505 * cache manager Venus issues a downcall to the kernel when this 
 506 * happens 
 507 */
 508int coda_revalidate_inode(struct inode *inode)
 509{
 510        struct coda_vattr attr;
 511        int error;
 512        int old_mode;
 513        ino_t old_ino;
 514        struct coda_inode_info *cii = ITOC(inode);
 515
 516        if (!cii->c_flags)
 517                return 0;
 518
 519        if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
 520                error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
 521                if (error)
 522                        return -EIO;
 523
 524                /* this inode may be lost if:
 525                   - it's ino changed 
 526                   - type changes must be permitted for repair and
 527                   missing mount points.
 528                */
 529                old_mode = inode->i_mode;
 530                old_ino = inode->i_ino;
 531                coda_vattr_to_iattr(inode, &attr);
 532
 533                if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
 534                        pr_warn("inode %ld, fid %s changed type!\n",
 535                                inode->i_ino, coda_f2s(&(cii->c_fid)));
 536                }
 537
 538                /* the following can happen when a local fid is replaced 
 539                   with a global one, here we lose and declare the inode bad */
 540                if (inode->i_ino != old_ino)
 541                        return -EIO;
 542                
 543                coda_flag_inode_children(inode, C_FLUSH);
 544
 545                spin_lock(&cii->c_lock);
 546                cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
 547                spin_unlock(&cii->c_lock);
 548        }
 549        return 0;
 550}
 551
 552const struct dentry_operations coda_dentry_operations = {
 553        .d_revalidate   = coda_dentry_revalidate,
 554        .d_delete       = coda_dentry_delete,
 555};
 556
 557const struct inode_operations coda_dir_inode_operations = {
 558        .create         = coda_create,
 559        .lookup         = coda_lookup,
 560        .link           = coda_link,
 561        .unlink         = coda_unlink,
 562        .symlink        = coda_symlink,
 563        .mkdir          = coda_mkdir,
 564        .rmdir          = coda_rmdir,
 565        .mknod          = CODA_EIO_ERROR,
 566        .rename         = coda_rename,
 567        .permission     = coda_permission,
 568        .getattr        = coda_getattr,
 569        .setattr        = coda_setattr,
 570};
 571
 572const struct file_operations coda_dir_operations = {
 573        .llseek         = generic_file_llseek,
 574        .read           = generic_read_dir,
 575        .iterate        = coda_readdir,
 576        .open           = coda_open,
 577        .release        = coda_release,
 578        .fsync          = coda_fsync,
 579};
 580