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