fs/afs/dir.c

   1 /* dir.c: AFS filesystem directory handling
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/sched.h>
  16 #include <linux/slab.h>
  17 #include <linux/fs.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/smp_lock.h>
  20 #include "vnode.h"
  21 #include "volume.h"
  22 #include <rxrpc/call.h>
  23 #include "super.h"
  24 #include "internal.h"
  25
  26 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
  27                                      struct nameidata *nd);
  28 static int afs_dir_open(struct inode *inode, struct file *file);
  29 static int afs_dir_readdir(struct file *file, void *dirent, filldir_t filldir);
  30 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd);
  31 static int afs_d_delete(struct dentry *dentry);
  32 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
  33                                   loff_t fpos, ino_t ino, unsigned dtype);
  34
  35 struct file_operations afs_dir_file_operations = {
  36         .open           = afs_dir_open,
  37         .readdir        = afs_dir_readdir,
  38 };
  39
  40 struct inode_operations afs_dir_inode_operations = {
  41         .lookup         = afs_dir_lookup,
  42         .getattr        = afs_inode_getattr,
  43 #if 0 /* TODO */
  44         .create         = afs_dir_create,
  45         .link           = afs_dir_link,
  46         .unlink         = afs_dir_unlink,
  47         .symlink        = afs_dir_symlink,
  48         .mkdir          = afs_dir_mkdir,
  49         .rmdir          = afs_dir_rmdir,
  50         .mknod          = afs_dir_mknod,
  51         .rename         = afs_dir_rename,
  52 #endif
  53 };
  54
  55 static struct dentry_operations afs_fs_dentry_operations = {
  56         .d_revalidate   = afs_d_revalidate,
  57         .d_delete       = afs_d_delete,
  58 };
  59
  60 #define AFS_DIR_HASHTBL_SIZE    128
  61 #define AFS_DIR_DIRENT_SIZE     32
  62 #define AFS_DIRENT_PER_BLOCK    64
  63
  64 union afs_dirent {
  65         struct {
  66                 uint8_t         valid;
  67                 uint8_t         unused[1];
  68                 __be16          hash_next;
  69                 __be32          vnode;
  70                 __be32          unique;
  71                 uint8_t         name[16];
  72                 uint8_t         overflow[4];    /* if any char of the name (inc
  73                                                  * NUL) reaches here, consume
  74                                                  * the next dirent too */
  75         } u;
  76         uint8_t extended_name[32];
  77 };
  78
  79 /* AFS directory page header (one at the beginning of every 2048-byte chunk) */
  80 struct afs_dir_pagehdr {
  81         __be16          npages;
  82         __be16          magic;
  83 #define AFS_DIR_MAGIC htons(1234)
  84         uint8_t         nentries;
  85         uint8_t         bitmap[8];
  86         uint8_t         pad[19];
  87 };
  88
  89 /* directory block layout */
  90 union afs_dir_block {
  91
  92         struct afs_dir_pagehdr pagehdr;
  93
  94         struct {
  95                 struct afs_dir_pagehdr  pagehdr;
  96                 uint8_t                 alloc_ctrs[128];
  97                 /* dir hash table */
  98                 uint16_t                hashtable[AFS_DIR_HASHTBL_SIZE];
  99         } hdr;
 100
 101         union afs_dirent dirents[AFS_DIRENT_PER_BLOCK];
 102 };
 103
 104 /* layout on a linux VM page */
 105 struct afs_dir_page {
 106         union afs_dir_block blocks[PAGE_SIZE / sizeof(union afs_dir_block)];
 107 };
 108
 109 struct afs_dir_lookup_cookie {
 110         struct afs_fid  fid;
 111         const char      *name;
 112         size_t          nlen;
 113         int             found;
 114 };
 115
 116 /*****************************************************************************/
 117 /*
 118  * check that a directory page is valid
 119  */
 120 static inline void afs_dir_check_page(struct inode *dir, struct page *page)
 121 {
 122         struct afs_dir_page *dbuf;
 123         loff_t latter;
 124         int tmp, qty;
 125
 126 #if 0
 127         /* check the page count */
 128         qty = desc.size / sizeof(dbuf->blocks[0]);
 129         if (qty == 0)
 130                 goto error;
 131
 132         if (page->index==0 && qty!=ntohs(dbuf->blocks[0].pagehdr.npages)) {
 133                 printk("kAFS: %s(%lu): wrong number of dir blocks %d!=%hu\n",
 134                        __FUNCTION__,dir->i_ino,qty,ntohs(dbuf->blocks[0].pagehdr.npages));
 135                 goto error;
 136         }
 137 #endif
 138
 139         /* determine how many magic numbers there should be in this page */
 140         latter = dir->i_size - page_offset(page);
 141         if (latter >= PAGE_SIZE)
 142                 qty = PAGE_SIZE;
 143         else
 144                 qty = latter;
 145         qty /= sizeof(union afs_dir_block);
 146
 147         /* check them */
 148         dbuf = page_address(page);
 149         for (tmp = 0; tmp < qty; tmp++) {
 150                 if (dbuf->blocks[tmp].pagehdr.magic != AFS_DIR_MAGIC) {
 151                         printk("kAFS: %s(%lu): bad magic %d/%d is %04hx\n",
 152                                __FUNCTION__, dir->i_ino, tmp, qty,
 153                                ntohs(dbuf->blocks[tmp].pagehdr.magic));
 154                         goto error;
 155                 }
 156         }
 157
 158         SetPageChecked(page);
 159         return;
 160
 161  error:
 162         SetPageChecked(page);
 163         SetPageError(page);
 164
 165 } /* end afs_dir_check_page() */
 166
 167 /*****************************************************************************/
 168 /*
 169  * discard a page cached in the pagecache
 170  */
 171 static inline void afs_dir_put_page(struct page *page)
 172 {
 173         kunmap(page);
 174         page_cache_release(page);
 175
 176 } /* end afs_dir_put_page() */
 177
 178 /*****************************************************************************/
 179 /*
 180  * get a page into the pagecache
 181  */
 182 static struct page *afs_dir_get_page(struct inode *dir, unsigned long index)
 183 {
 184         struct page *page;
 185
 186         _enter("{%lu},%lu", dir->i_ino, index);
 187
 188         page = read_cache_page(dir->i_mapping,index,
 189                                (filler_t *) dir->i_mapping->a_ops->readpage,
 190                                NULL);
 191         if (!IS_ERR(page)) {
 192                 wait_on_page_locked(page);
 193                 kmap(page);
 194                 if (!PageUptodate(page))
 195                         goto fail;
 196                 if (!PageChecked(page))
 197                         afs_dir_check_page(dir, page);
 198                 if (PageError(page))
 199                         goto fail;
 200         }
 201         return page;
 202
 203  fail:
 204         afs_dir_put_page(page);
 205         return ERR_PTR(-EIO);
 206 } /* end afs_dir_get_page() */
 207
 208 /*****************************************************************************/
 209 /*
 210  * open an AFS directory file
 211  */
 212 static int afs_dir_open(struct inode *inode, struct file *file)
 213 {
 214         _enter("{%lu}", inode->i_ino);
 215
 216         BUG_ON(sizeof(union afs_dir_block) != 2048);
 217         BUG_ON(sizeof(union afs_dirent) != 32);
 218
 219         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED)
 220                 return -ENOENT;
 221
 222         _leave(" = 0");
 223         return 0;
 224
 225 } /* end afs_dir_open() */
 226
 227 /*****************************************************************************/
 228 /*
 229  * deal with one block in an AFS directory
 230  */
 231 static int afs_dir_iterate_block(unsigned *fpos,
 232                                  union afs_dir_block *block,
 233                                  unsigned blkoff,
 234                                  void *cookie,
 235                                  filldir_t filldir)
 236 {
 237         union afs_dirent *dire;
 238         unsigned offset, next, curr;
 239         size_t nlen;
 240         int tmp, ret;
 241
 242         _enter("%u,%x,%p,,",*fpos,blkoff,block);
 243
 244         curr = (*fpos - blkoff) / sizeof(union afs_dirent);
 245
 246         /* walk through the block, an entry at a time */
 247         for (offset = AFS_DIRENT_PER_BLOCK - block->pagehdr.nentries;
 248              offset < AFS_DIRENT_PER_BLOCK;
 249              offset = next
 250              ) {
 251                 next = offset + 1;
 252
 253                 /* skip entries marked unused in the bitmap */
 254                 if (!(block->pagehdr.bitmap[offset / 8] &
 255                       (1 << (offset % 8)))) {
 256                         _debug("ENT[%Zu.%u]: unused\n",
 257                                blkoff / sizeof(union afs_dir_block), offset);
 258                         if (offset >= curr)
 259                                 *fpos = blkoff +
 260                                         next * sizeof(union afs_dirent);
 261                         continue;
 262                 }
 263
 264                 /* got a valid entry */
 265                 dire = &block->dirents[offset];
 266                 nlen = strnlen(dire->u.name,
 267                                sizeof(*block) -
 268                                offset * sizeof(union afs_dirent));
 269
 270                 _debug("ENT[%Zu.%u]: %s %Zu \"%s\"\n",
 271                        blkoff / sizeof(union afs_dir_block), offset,
 272                        (offset < curr ? "skip" : "fill"),
 273                        nlen, dire->u.name);
 274
 275                 /* work out where the next possible entry is */
 276                 for (tmp = nlen; tmp > 15; tmp -= sizeof(union afs_dirent)) {
 277                         if (next >= AFS_DIRENT_PER_BLOCK) {
 278                                 _debug("ENT[%Zu.%u]:"
 279                                        " %u travelled beyond end dir block"
 280                                        " (len %u/%Zu)\n",
 281                                        blkoff / sizeof(union afs_dir_block),
 282                                        offset, next, tmp, nlen);
 283                                 return -EIO;
 284                         }
 285                         if (!(block->pagehdr.bitmap[next / 8] &
 286                               (1 << (next % 8)))) {
 287                                 _debug("ENT[%Zu.%u]:"
 288                                        " %u unmarked extension (len %u/%Zu)\n",
 289                                        blkoff / sizeof(union afs_dir_block),
 290                                        offset, next, tmp, nlen);
 291                                 return -EIO;
 292                         }
 293
 294                         _debug("ENT[%Zu.%u]: ext %u/%Zu\n",
 295                                blkoff / sizeof(union afs_dir_block),
 296                                next, tmp, nlen);
 297                         next++;
 298                 }
 299
 300                 /* skip if starts before the current position */
 301                 if (offset < curr)
 302                         continue;
 303
 304                 /* found the next entry */
 305                 ret = filldir(cookie,
 306                               dire->u.name,
 307                               nlen,
 308                               blkoff + offset * sizeof(union afs_dirent),
 309                               ntohl(dire->u.vnode),
 310                               filldir == afs_dir_lookup_filldir ?
 311                               ntohl(dire->u.unique) : DT_UNKNOWN);
 312                 if (ret < 0) {
 313                         _leave(" = 0 [full]");
 314                         return 0;
 315                 }
 316
 317                 *fpos = blkoff + next * sizeof(union afs_dirent);
 318         }
 319
 320         _leave(" = 1 [more]");
 321         return 1;
 322 } /* end afs_dir_iterate_block() */
 323
 324 /*****************************************************************************/
 325 /*
 326  * read an AFS directory
 327  */
 328 static int afs_dir_iterate(struct inode *dir, unsigned *fpos, void *cookie,
 329                            filldir_t filldir)
 330 {
 331         union afs_dir_block     *dblock;
 332         struct afs_dir_page *dbuf;
 333         struct page *page;
 334         unsigned blkoff, limit;
 335         int ret;
 336
 337         _enter("{%lu},%u,,", dir->i_ino, *fpos);
 338
 339         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 340                 _leave(" = -ESTALE");
 341                 return -ESTALE;
 342         }
 343
 344         /* round the file position up to the next entry boundary */
 345         *fpos += sizeof(union afs_dirent) - 1;
 346         *fpos &= ~(sizeof(union afs_dirent) - 1);
 347
 348         /* walk through the blocks in sequence */
 349         ret = 0;
 350         while (*fpos < dir->i_size) {
 351                 blkoff = *fpos & ~(sizeof(union afs_dir_block) - 1);
 352
 353                 /* fetch the appropriate page from the directory */
 354                 page = afs_dir_get_page(dir, blkoff / PAGE_SIZE);
 355                 if (IS_ERR(page)) {
 356                         ret = PTR_ERR(page);
 357                         break;
 358                 }
 359
 360                 limit = blkoff & ~(PAGE_SIZE - 1);
 361
 362                 dbuf = page_address(page);
 363
 364                 /* deal with the individual blocks stashed on this page */
 365                 do {
 366                         dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
 367                                                sizeof(union afs_dir_block)];
 368                         ret = afs_dir_iterate_block(fpos, dblock, blkoff,
 369                                                     cookie, filldir);
 370                         if (ret != 1) {
 371                                 afs_dir_put_page(page);
 372                                 goto out;
 373                         }
 374
 375                         blkoff += sizeof(union afs_dir_block);
 376
 377                 } while (*fpos < dir->i_size && blkoff < limit);
 378
 379                 afs_dir_put_page(page);
 380                 ret = 0;
 381         }
 382
 383  out:
 384         _leave(" = %d", ret);
 385         return ret;
 386 } /* end afs_dir_iterate() */
 387
 388 /*****************************************************************************/
 389 /*
 390  * read an AFS directory
 391  */
 392 static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
 393 {
 394         unsigned fpos;
 395         int ret;
 396
 397         _enter("{%Ld,{%lu}}", file->f_pos, file->f_dentry->d_inode->i_ino);
 398
 399         fpos = file->f_pos;
 400         ret = afs_dir_iterate(file->f_dentry->d_inode, &fpos, cookie, filldir);
 401         file->f_pos = fpos;
 402
 403         _leave(" = %d", ret);
 404         return ret;
 405 } /* end afs_dir_readdir() */
 406
 407 /*****************************************************************************/
 408 /*
 409  * search the directory for a name
 410  * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 411  *   uniquifier through dtype
 412  */
 413 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
 414                                   loff_t fpos, ino_t ino, unsigned dtype)
 415 {
 416         struct afs_dir_lookup_cookie *cookie = _cookie;
 417
 418         _enter("{%s,%Zu},%s,%u,,%lu,%u",
 419                cookie->name, cookie->nlen, name, nlen, ino, dtype);
 420
 421         if (cookie->nlen != nlen || memcmp(cookie->name, name, nlen) != 0) {
 422                 _leave(" = 0 [no]");
 423                 return 0;
 424         }
 425
 426         cookie->fid.vnode = ino;
 427         cookie->fid.unique = dtype;
 428         cookie->found = 1;
 429
 430         _leave(" = -1 [found]");
 431         return -1;
 432 } /* end afs_dir_lookup_filldir() */
 433
 434 /*****************************************************************************/
 435 /*
 436  * look up an entry in a directory
 437  */
 438 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
 439                                      struct nameidata *nd)
 440 {
 441         struct afs_dir_lookup_cookie cookie;
 442         struct afs_super_info *as;
 443         struct afs_vnode *vnode;
 444         struct inode *inode;
 445         unsigned fpos;
 446         int ret;
 447
 448         _enter("{%lu},%p{%s}", dir->i_ino, dentry, dentry->d_name.name);
 449
 450         /* insanity checks first */
 451         BUG_ON(sizeof(union afs_dir_block) != 2048);
 452         BUG_ON(sizeof(union afs_dirent) != 32);
 453
 454         if (dentry->d_name.len > 255) {
 455                 _leave(" = -ENAMETOOLONG");
 456                 return ERR_PTR(-ENAMETOOLONG);
 457         }
 458
 459         vnode = AFS_FS_I(dir);
 460         if (vnode->flags & AFS_VNODE_DELETED) {
 461                 _leave(" = -ESTALE");
 462                 return ERR_PTR(-ESTALE);
 463         }
 464
 465         as = dir->i_sb->s_fs_info;
 466
 467         /* search the directory */
 468         cookie.name     = dentry->d_name.name;
 469         cookie.nlen     = dentry->d_name.len;
 470         cookie.fid.vid  = as->volume->vid;
 471         cookie.found    = 0;
 472
 473         fpos = 0;
 474         ret = afs_dir_iterate(dir, &fpos, &cookie, afs_dir_lookup_filldir);
 475         if (ret < 0) {
 476                 _leave(" = %d", ret);
 477                 return ERR_PTR(ret);
 478         }
 479
 480         ret = -ENOENT;
 481         if (!cookie.found) {
 482                 _leave(" = %d", ret);
 483                 return ERR_PTR(ret);
 484         }
 485
 486         /* instantiate the dentry */
 487         ret = afs_iget(dir->i_sb, &cookie.fid, &inode);
 488         if (ret < 0) {
 489                 _leave(" = %d", ret);
 490                 return ERR_PTR(ret);
 491         }
 492
 493         dentry->d_op = &afs_fs_dentry_operations;
 494         dentry->d_fsdata = (void *) (unsigned long) vnode->status.version;
 495
 496         d_add(dentry, inode);
 497         _leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
 498                cookie.fid.vnode,
 499                cookie.fid.unique,
 500                dentry->d_inode->i_ino,
 501                dentry->d_inode->i_version);
 502
 503         return NULL;
 504 } /* end afs_dir_lookup() */
 505
 506 /*****************************************************************************/
 507 /*
 508  * check that a dentry lookup hit has found a valid entry
 509  * - NOTE! the hit can be a negative hit too, so we can't assume we have an
 510  *   inode
 511  * (derived from nfs_lookup_revalidate)
 512  */
 513 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 514 {
 515         struct afs_dir_lookup_cookie cookie;
 516         struct dentry *parent;
 517         struct inode *inode, *dir;
 518         unsigned fpos;
 519         int ret;
 520
 521         _enter("{sb=%p n=%s},", dentry->d_sb, dentry->d_name.name);
 522
 523         /* lock down the parent dentry so we can peer at it */
 524         parent = dget_parent(dentry->d_parent);
 525
 526         dir = parent->d_inode;
 527         inode = dentry->d_inode;
 528
 529         /* handle a negative dentry */
 530         if (!inode)
 531                 goto out_bad;
 532
 533         /* handle a bad inode */
 534         if (is_bad_inode(inode)) {
 535                 printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
 536                        dentry->d_parent->d_name.name, dentry->d_name.name);
 537                 goto out_bad;
 538         }
 539
 540         /* force a full look up if the parent directory changed since last the
 541          * server was consulted
 542          * - otherwise this inode must still exist, even if the inode details
 543          *   themselves have changed
 544          */
 545         if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
 546                 afs_vnode_fetch_status(AFS_FS_I(dir));
 547
 548         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 549                 _debug("%s: parent dir deleted", dentry->d_name.name);
 550                 goto out_bad;
 551         }
 552
 553         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
 554                 _debug("%s: file already deleted", dentry->d_name.name);
 555                 goto out_bad;
 556         }
 557
 558         if ((unsigned long) dentry->d_fsdata !=
 559             (unsigned long) AFS_FS_I(dir)->status.version) {
 560                 _debug("%s: parent changed %lu -> %u",
 561                        dentry->d_name.name,
 562                        (unsigned long) dentry->d_fsdata,
 563                        (unsigned) AFS_FS_I(dir)->status.version);
 564
 565                 /* search the directory for this vnode */
 566                 cookie.name     = dentry->d_name.name;
 567                 cookie.nlen     = dentry->d_name.len;
 568                 cookie.fid.vid  = AFS_FS_I(inode)->volume->vid;
 569                 cookie.found    = 0;
 570
 571                 fpos = 0;
 572                 ret = afs_dir_iterate(dir, &fpos, &cookie,
 573                                       afs_dir_lookup_filldir);
 574                 if (ret < 0) {
 575                         _debug("failed to iterate dir %s: %d",
 576                                parent->d_name.name, ret);
 577                         goto out_bad;
 578                 }
 579
 580                 if (!cookie.found) {
 581                         _debug("%s: dirent not found", dentry->d_name.name);
 582                         goto not_found;
 583                 }
 584
 585                 /* if the vnode ID has changed, then the dirent points to a
 586                  * different file */
 587                 if (cookie.fid.vnode != AFS_FS_I(inode)->fid.vnode) {
 588                         _debug("%s: dirent changed", dentry->d_name.name);
 589                         goto not_found;
 590                 }
 591
 592                 /* if the vnode ID uniqifier has changed, then the file has
 593                  * been deleted */
 594                 if (cookie.fid.unique != AFS_FS_I(inode)->fid.unique) {
 595                         _debug("%s: file deleted (uq %u -> %u I:%lu)",
 596                                dentry->d_name.name,
 597                                cookie.fid.unique,
 598                                AFS_FS_I(inode)->fid.unique,
 599                                inode->i_version);
 600                         spin_lock(&AFS_FS_I(inode)->lock);
 601                         AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
 602                         spin_unlock(&AFS_FS_I(inode)->lock);
 603                         invalidate_remote_inode(inode);
 604                         goto out_bad;
 605                 }
 606
 607                 dentry->d_fsdata =
 608                         (void *) (unsigned long) AFS_FS_I(dir)->status.version;
 609         }
 610
 611  out_valid:
 612         dput(parent);
 613         _leave(" = 1 [valid]");
 614         return 1;
 615
 616         /* the dirent, if it exists, now points to a different vnode */
 617  not_found:
 618         spin_lock(&dentry->d_lock);
 619         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 620         spin_unlock(&dentry->d_lock);
 621
 622  out_bad:
 623         if (inode) {
 624                 /* don't unhash if we have submounts */
 625                 if (have_submounts(dentry))
 626                         goto out_valid;
 627         }
 628
 629         shrink_dcache_parent(dentry);
 630
 631         _debug("dropping dentry %s/%s",
 632                dentry->d_parent->d_name.name, dentry->d_name.name);
 633         d_drop(dentry);
 634
 635         dput(parent);
 636
 637         _leave(" = 0 [bad]");
 638         return 0;
 639 } /* end afs_d_revalidate() */
 640
 641 /*****************************************************************************/
 642 /*
 643  * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 644  * sleep)
 645  * - called from dput() when d_count is going to 0.
 646  * - return 1 to request dentry be unhashed, 0 otherwise
 647  */
 648 static int afs_d_delete(struct dentry *dentry)
 649 {
 650         _enter("%s", dentry->d_name.name);
 651
 652         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 653                 goto zap;
 654
 655         if (dentry->d_inode) {
 656                 if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
 657                         goto zap;
 658         }
 659
 660         _leave(" = 0 [keep]");
 661         return 0;
 662
 663  zap:
 664         _leave(" = 1 [zap]");
 665         return 1;
 666 } /* end afs_d_delete() */