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, u64 ino, unsigned dtype);
  34
  35 const 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_mapping_page(dir->i_mapping, index, NULL);
 189         if (!IS_ERR(page)) {
 190                 wait_on_page_locked(page);
 191                 kmap(page);
 192                 if (!PageUptodate(page))
 193                         goto fail;
 194                 if (!PageChecked(page))
 195                         afs_dir_check_page(dir, page);
 196                 if (PageError(page))
 197                         goto fail;
 198         }
 199         return page;
 200
 201  fail:
 202         afs_dir_put_page(page);
 203         return ERR_PTR(-EIO);
 204 } /* end afs_dir_get_page() */
 205
 206 /*****************************************************************************/
 207 /*
 208  * open an AFS directory file
 209  */
 210 static int afs_dir_open(struct inode *inode, struct file *file)
 211 {
 212         _enter("{%lu}", inode->i_ino);
 213
 214         BUG_ON(sizeof(union afs_dir_block) != 2048);
 215         BUG_ON(sizeof(union afs_dirent) != 32);
 216
 217         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED)
 218                 return -ENOENT;
 219
 220         _leave(" = 0");
 221         return 0;
 222
 223 } /* end afs_dir_open() */
 224
 225 /*****************************************************************************/
 226 /*
 227  * deal with one block in an AFS directory
 228  */
 229 static int afs_dir_iterate_block(unsigned *fpos,
 230                                  union afs_dir_block *block,
 231                                  unsigned blkoff,
 232                                  void *cookie,
 233                                  filldir_t filldir)
 234 {
 235         union afs_dirent *dire;
 236         unsigned offset, next, curr;
 237         size_t nlen;
 238         int tmp, ret;
 239
 240         _enter("%u,%x,%p,,",*fpos,blkoff,block);
 241
 242         curr = (*fpos - blkoff) / sizeof(union afs_dirent);
 243
 244         /* walk through the block, an entry at a time */
 245         for (offset = AFS_DIRENT_PER_BLOCK - block->pagehdr.nentries;
 246              offset < AFS_DIRENT_PER_BLOCK;
 247              offset = next
 248              ) {
 249                 next = offset + 1;
 250
 251                 /* skip entries marked unused in the bitmap */
 252                 if (!(block->pagehdr.bitmap[offset / 8] &
 253                       (1 << (offset % 8)))) {
 254                         _debug("ENT[%Zu.%u]: unused\n",
 255                                blkoff / sizeof(union afs_dir_block), offset);
 256                         if (offset >= curr)
 257                                 *fpos = blkoff +
 258                                         next * sizeof(union afs_dirent);
 259                         continue;
 260                 }
 261
 262                 /* got a valid entry */
 263                 dire = &block->dirents[offset];
 264                 nlen = strnlen(dire->u.name,
 265                                sizeof(*block) -
 266                                offset * sizeof(union afs_dirent));
 267
 268                 _debug("ENT[%Zu.%u]: %s %Zu \"%s\"\n",
 269                        blkoff / sizeof(union afs_dir_block), offset,
 270                        (offset < curr ? "skip" : "fill"),
 271                        nlen, dire->u.name);
 272
 273                 /* work out where the next possible entry is */
 274                 for (tmp = nlen; tmp > 15; tmp -= sizeof(union afs_dirent)) {
 275                         if (next >= AFS_DIRENT_PER_BLOCK) {
 276                                 _debug("ENT[%Zu.%u]:"
 277                                        " %u travelled beyond end dir block"
 278                                        " (len %u/%Zu)\n",
 279                                        blkoff / sizeof(union afs_dir_block),
 280                                        offset, next, tmp, nlen);
 281                                 return -EIO;
 282                         }
 283                         if (!(block->pagehdr.bitmap[next / 8] &
 284                               (1 << (next % 8)))) {
 285                                 _debug("ENT[%Zu.%u]:"
 286                                        " %u unmarked extension (len %u/%Zu)\n",
 287                                        blkoff / sizeof(union afs_dir_block),
 288                                        offset, next, tmp, nlen);
 289                                 return -EIO;
 290                         }
 291
 292                         _debug("ENT[%Zu.%u]: ext %u/%Zu\n",
 293                                blkoff / sizeof(union afs_dir_block),
 294                                next, tmp, nlen);
 295                         next++;
 296                 }
 297
 298                 /* skip if starts before the current position */
 299                 if (offset < curr)
 300                         continue;
 301
 302                 /* found the next entry */
 303                 ret = filldir(cookie,
 304                               dire->u.name,
 305                               nlen,
 306                               blkoff + offset * sizeof(union afs_dirent),
 307                               ntohl(dire->u.vnode),
 308                               filldir == afs_dir_lookup_filldir ?
 309                               ntohl(dire->u.unique) : DT_UNKNOWN);
 310                 if (ret < 0) {
 311                         _leave(" = 0 [full]");
 312                         return 0;
 313                 }
 314
 315                 *fpos = blkoff + next * sizeof(union afs_dirent);
 316         }
 317
 318         _leave(" = 1 [more]");
 319         return 1;
 320 } /* end afs_dir_iterate_block() */
 321
 322 /*****************************************************************************/
 323 /*
 324  * read an AFS directory
 325  */
 326 static int afs_dir_iterate(struct inode *dir, unsigned *fpos, void *cookie,
 327                            filldir_t filldir)
 328 {
 329         union afs_dir_block     *dblock;
 330         struct afs_dir_page *dbuf;
 331         struct page *page;
 332         unsigned blkoff, limit;
 333         int ret;
 334
 335         _enter("{%lu},%u,,", dir->i_ino, *fpos);
 336
 337         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 338                 _leave(" = -ESTALE");
 339                 return -ESTALE;
 340         }
 341
 342         /* round the file position up to the next entry boundary */
 343         *fpos += sizeof(union afs_dirent) - 1;
 344         *fpos &= ~(sizeof(union afs_dirent) - 1);
 345
 346         /* walk through the blocks in sequence */
 347         ret = 0;
 348         while (*fpos < dir->i_size) {
 349                 blkoff = *fpos & ~(sizeof(union afs_dir_block) - 1);
 350
 351                 /* fetch the appropriate page from the directory */
 352                 page = afs_dir_get_page(dir, blkoff / PAGE_SIZE);
 353                 if (IS_ERR(page)) {
 354                         ret = PTR_ERR(page);
 355                         break;
 356                 }
 357
 358                 limit = blkoff & ~(PAGE_SIZE - 1);
 359
 360                 dbuf = page_address(page);
 361
 362                 /* deal with the individual blocks stashed on this page */
 363                 do {
 364                         dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
 365                                                sizeof(union afs_dir_block)];
 366                         ret = afs_dir_iterate_block(fpos, dblock, blkoff,
 367                                                     cookie, filldir);
 368                         if (ret != 1) {
 369                                 afs_dir_put_page(page);
 370                                 goto out;
 371                         }
 372
 373                         blkoff += sizeof(union afs_dir_block);
 374
 375                 } while (*fpos < dir->i_size && blkoff < limit);
 376
 377                 afs_dir_put_page(page);
 378                 ret = 0;
 379         }
 380
 381  out:
 382         _leave(" = %d", ret);
 383         return ret;
 384 } /* end afs_dir_iterate() */
 385
 386 /*****************************************************************************/
 387 /*
 388  * read an AFS directory
 389  */
 390 static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
 391 {
 392         unsigned fpos;
 393         int ret;
 394
 395         _enter("{%Ld,{%lu}}", file->f_pos, file->f_dentry->d_inode->i_ino);
 396
 397         fpos = file->f_pos;
 398         ret = afs_dir_iterate(file->f_dentry->d_inode, &fpos, cookie, filldir);
 399         file->f_pos = fpos;
 400
 401         _leave(" = %d", ret);
 402         return ret;
 403 } /* end afs_dir_readdir() */
 404
 405 /*****************************************************************************/
 406 /*
 407  * search the directory for a name
 408  * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 409  *   uniquifier through dtype
 410  */
 411 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
 412                                   loff_t fpos, u64 ino, unsigned dtype)
 413 {
 414         struct afs_dir_lookup_cookie *cookie = _cookie;
 415
 416         _enter("{%s,%Zu},%s,%u,,%lu,%u",
 417                cookie->name, cookie->nlen, name, nlen, ino, dtype);
 418
 419         if (cookie->nlen != nlen || memcmp(cookie->name, name, nlen) != 0) {
 420                 _leave(" = 0 [no]");
 421                 return 0;
 422         }
 423
 424         cookie->fid.vnode = ino;
 425         cookie->fid.unique = dtype;
 426         cookie->found = 1;
 427
 428         _leave(" = -1 [found]");
 429         return -1;
 430 } /* end afs_dir_lookup_filldir() */
 431
 432 /*****************************************************************************/
 433 /*
 434  * look up an entry in a directory
 435  */
 436 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
 437                                      struct nameidata *nd)
 438 {
 439         struct afs_dir_lookup_cookie cookie;
 440         struct afs_super_info *as;
 441         struct afs_vnode *vnode;
 442         struct inode *inode;
 443         unsigned fpos;
 444         int ret;
 445
 446         _enter("{%lu},%p{%s}", dir->i_ino, dentry, dentry->d_name.name);
 447
 448         /* insanity checks first */
 449         BUG_ON(sizeof(union afs_dir_block) != 2048);
 450         BUG_ON(sizeof(union afs_dirent) != 32);
 451
 452         if (dentry->d_name.len > 255) {
 453                 _leave(" = -ENAMETOOLONG");
 454                 return ERR_PTR(-ENAMETOOLONG);
 455         }
 456
 457         vnode = AFS_FS_I(dir);
 458         if (vnode->flags & AFS_VNODE_DELETED) {
 459                 _leave(" = -ESTALE");
 460                 return ERR_PTR(-ESTALE);
 461         }
 462
 463         as = dir->i_sb->s_fs_info;
 464
 465         /* search the directory */
 466         cookie.name     = dentry->d_name.name;
 467         cookie.nlen     = dentry->d_name.len;
 468         cookie.fid.vid  = as->volume->vid;
 469         cookie.found    = 0;
 470
 471         fpos = 0;
 472         ret = afs_dir_iterate(dir, &fpos, &cookie, afs_dir_lookup_filldir);
 473         if (ret < 0) {
 474                 _leave(" = %d", ret);
 475                 return ERR_PTR(ret);
 476         }
 477
 478         ret = -ENOENT;
 479         if (!cookie.found) {
 480                 _leave(" = %d", ret);
 481                 return ERR_PTR(ret);
 482         }
 483
 484         /* instantiate the dentry */
 485         ret = afs_iget(dir->i_sb, &cookie.fid, &inode);
 486         if (ret < 0) {
 487                 _leave(" = %d", ret);
 488                 return ERR_PTR(ret);
 489         }
 490
 491         dentry->d_op = &afs_fs_dentry_operations;
 492         dentry->d_fsdata = (void *) (unsigned long) vnode->status.version;
 493
 494         d_add(dentry, inode);
 495         _leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
 496                cookie.fid.vnode,
 497                cookie.fid.unique,
 498                dentry->d_inode->i_ino,
 499                dentry->d_inode->i_version);
 500
 501         return NULL;
 502 } /* end afs_dir_lookup() */
 503
 504 /*****************************************************************************/
 505 /*
 506  * check that a dentry lookup hit has found a valid entry
 507  * - NOTE! the hit can be a negative hit too, so we can't assume we have an
 508  *   inode
 509  * (derived from nfs_lookup_revalidate)
 510  */
 511 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 512 {
 513         struct afs_dir_lookup_cookie cookie;
 514         struct dentry *parent;
 515         struct inode *inode, *dir;
 516         unsigned fpos;
 517         int ret;
 518
 519         _enter("{sb=%p n=%s},", dentry->d_sb, dentry->d_name.name);
 520
 521         /* lock down the parent dentry so we can peer at it */
 522         parent = dget_parent(dentry->d_parent);
 523
 524         dir = parent->d_inode;
 525         inode = dentry->d_inode;
 526
 527         /* handle a negative dentry */
 528         if (!inode)
 529                 goto out_bad;
 530
 531         /* handle a bad inode */
 532         if (is_bad_inode(inode)) {
 533                 printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
 534                        dentry->d_parent->d_name.name, dentry->d_name.name);
 535                 goto out_bad;
 536         }
 537
 538         /* force a full look up if the parent directory changed since last the
 539          * server was consulted
 540          * - otherwise this inode must still exist, even if the inode details
 541          *   themselves have changed
 542          */
 543         if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
 544                 afs_vnode_fetch_status(AFS_FS_I(dir));
 545
 546         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 547                 _debug("%s: parent dir deleted", dentry->d_name.name);
 548                 goto out_bad;
 549         }
 550
 551         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
 552                 _debug("%s: file already deleted", dentry->d_name.name);
 553                 goto out_bad;
 554         }
 555
 556         if ((unsigned long) dentry->d_fsdata !=
 557             (unsigned long) AFS_FS_I(dir)->status.version) {
 558                 _debug("%s: parent changed %lu -> %u",
 559                        dentry->d_name.name,
 560                        (unsigned long) dentry->d_fsdata,
 561                        (unsigned) AFS_FS_I(dir)->status.version);
 562
 563                 /* search the directory for this vnode */
 564                 cookie.name     = dentry->d_name.name;
 565                 cookie.nlen     = dentry->d_name.len;
 566                 cookie.fid.vid  = AFS_FS_I(inode)->volume->vid;
 567                 cookie.found    = 0;
 568
 569                 fpos = 0;
 570                 ret = afs_dir_iterate(dir, &fpos, &cookie,
 571                                       afs_dir_lookup_filldir);
 572                 if (ret < 0) {
 573                         _debug("failed to iterate dir %s: %d",
 574                                parent->d_name.name, ret);
 575                         goto out_bad;
 576                 }
 577
 578                 if (!cookie.found) {
 579                         _debug("%s: dirent not found", dentry->d_name.name);
 580                         goto not_found;
 581                 }
 582
 583                 /* if the vnode ID has changed, then the dirent points to a
 584                  * different file */
 585                 if (cookie.fid.vnode != AFS_FS_I(inode)->fid.vnode) {
 586                         _debug("%s: dirent changed", dentry->d_name.name);
 587                         goto not_found;
 588                 }
 589
 590                 /* if the vnode ID uniqifier has changed, then the file has
 591                  * been deleted */
 592                 if (cookie.fid.unique != AFS_FS_I(inode)->fid.unique) {
 593                         _debug("%s: file deleted (uq %u -> %u I:%lu)",
 594                                dentry->d_name.name,
 595                                cookie.fid.unique,
 596                                AFS_FS_I(inode)->fid.unique,
 597                                inode->i_version);
 598                         spin_lock(&AFS_FS_I(inode)->lock);
 599                         AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
 600                         spin_unlock(&AFS_FS_I(inode)->lock);
 601                         invalidate_remote_inode(inode);
 602                         goto out_bad;
 603                 }
 604
 605                 dentry->d_fsdata =
 606                         (void *) (unsigned long) AFS_FS_I(dir)->status.version;
 607         }
 608
 609  out_valid:
 610         dput(parent);
 611         _leave(" = 1 [valid]");
 612         return 1;
 613
 614         /* the dirent, if it exists, now points to a different vnode */
 615  not_found:
 616         spin_lock(&dentry->d_lock);
 617         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 618         spin_unlock(&dentry->d_lock);
 619
 620  out_bad:
 621         if (inode) {
 622                 /* don't unhash if we have submounts */
 623                 if (have_submounts(dentry))
 624                         goto out_valid;
 625         }
 626
 627         shrink_dcache_parent(dentry);
 628
 629         _debug("dropping dentry %s/%s",
 630                dentry->d_parent->d_name.name, dentry->d_name.name);
 631         d_drop(dentry);
 632
 633         dput(parent);
 634
 635         _leave(" = 0 [bad]");
 636         return 0;
 637 } /* end afs_d_revalidate() */
 638
 639 /*****************************************************************************/
 640 /*
 641  * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 642  * sleep)
 643  * - called from dput() when d_count is going to 0.
 644  * - return 1 to request dentry be unhashed, 0 otherwise
 645  */
 646 static int afs_d_delete(struct dentry *dentry)
 647 {
 648         _enter("%s", dentry->d_name.name);
 649
 650         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 651                 goto zap;
 652
 653         if (dentry->d_inode) {
 654                 if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
 655                         goto zap;
 656         }
 657
 658         _leave(" = 0 [keep]");
 659         return 0;
 660
 661  zap:
 662         _leave(" = 1 [zap]");
 663         return 1;
 664 } /* end afs_d_delete() */