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/slab.h>
  16 #include <linux/fs.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/smp_lock.h>
  19 #include "vnode.h"
  20 #include "volume.h"
  21 #include <rxrpc/call.h>
  22 #include "super.h"
  23 #include "internal.h"
  24
  25 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
  26                                      struct nameidata *nd);
  27 static int afs_dir_open(struct inode *inode, struct file *file);
  28 static int afs_dir_readdir(struct file *file, void *dirent, filldir_t filldir);
  29 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd);
  30 static int afs_d_delete(struct dentry *dentry);
  31 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
  32                                   loff_t fpos, u64 ino, unsigned dtype);
  33
  34 const struct file_operations afs_dir_file_operations = {
  35         .open           = afs_dir_open,
  36         .readdir        = afs_dir_readdir,
  37 };
  38
  39 const struct inode_operations afs_dir_inode_operations = {
  40         .lookup         = afs_dir_lookup,
  41         .getattr        = afs_inode_getattr,
  42 #if 0 /* TODO */
  43         .create         = afs_dir_create,
  44         .link           = afs_dir_link,
  45         .unlink         = afs_dir_unlink,
  46         .symlink        = afs_dir_symlink,
  47         .mkdir          = afs_dir_mkdir,
  48         .rmdir          = afs_dir_rmdir,
  49         .mknod          = afs_dir_mknod,
  50         .rename         = afs_dir_rename,
  51 #endif
  52 };
  53
  54 static struct dentry_operations afs_fs_dentry_operations = {
  55         .d_revalidate   = afs_d_revalidate,
  56         .d_delete       = afs_d_delete,
  57 };
  58
  59 #define AFS_DIR_HASHTBL_SIZE    128
  60 #define AFS_DIR_DIRENT_SIZE     32
  61 #define AFS_DIRENT_PER_BLOCK    64
  62
  63 union afs_dirent {
  64         struct {
  65                 uint8_t         valid;
  66                 uint8_t         unused[1];
  67                 __be16          hash_next;
  68                 __be32          vnode;
  69                 __be32          unique;
  70                 uint8_t         name[16];
  71                 uint8_t         overflow[4];    /* if any char of the name (inc
  72                                                  * NUL) reaches here, consume
  73                                                  * the next dirent too */
  74         } u;
  75         uint8_t extended_name[32];
  76 };
  77
  78 /* AFS directory page header (one at the beginning of every 2048-byte chunk) */
  79 struct afs_dir_pagehdr {
  80         __be16          npages;
  81         __be16          magic;
  82 #define AFS_DIR_MAGIC htons(1234)
  83         uint8_t         nentries;
  84         uint8_t         bitmap[8];
  85         uint8_t         pad[19];
  86 };
  87
  88 /* directory block layout */
  89 union afs_dir_block {
  90
  91         struct afs_dir_pagehdr pagehdr;
  92
  93         struct {
  94                 struct afs_dir_pagehdr  pagehdr;
  95                 uint8_t                 alloc_ctrs[128];
  96                 /* dir hash table */
  97                 uint16_t                hashtable[AFS_DIR_HASHTBL_SIZE];
  98         } hdr;
  99
 100         union afs_dirent dirents[AFS_DIRENT_PER_BLOCK];
 101 };
 102
 103 /* layout on a linux VM page */
 104 struct afs_dir_page {
 105         union afs_dir_block blocks[PAGE_SIZE / sizeof(union afs_dir_block)];
 106 };
 107
 108 struct afs_dir_lookup_cookie {
 109         struct afs_fid  fid;
 110         const char      *name;
 111         size_t          nlen;
 112         int             found;
 113 };
 114
 115 /*****************************************************************************/
 116 /*
 117  * check that a directory page is valid
 118  */
 119 static inline void afs_dir_check_page(struct inode *dir, struct page *page)
 120 {
 121         struct afs_dir_page *dbuf;
 122         loff_t latter;
 123         int tmp, qty;
 124
 125 #if 0
 126         /* check the page count */
 127         qty = desc.size / sizeof(dbuf->blocks[0]);
 128         if (qty == 0)
 129                 goto error;
 130
 131         if (page->index==0 && qty!=ntohs(dbuf->blocks[0].pagehdr.npages)) {
 132                 printk("kAFS: %s(%lu): wrong number of dir blocks %d!=%hu\n",
 133                        __FUNCTION__,dir->i_ino,qty,ntohs(dbuf->blocks[0].pagehdr.npages));
 134                 goto error;
 135         }
 136 #endif
 137
 138         /* determine how many magic numbers there should be in this page */
 139         latter = dir->i_size - page_offset(page);
 140         if (latter >= PAGE_SIZE)
 141                 qty = PAGE_SIZE;
 142         else
 143                 qty = latter;
 144         qty /= sizeof(union afs_dir_block);
 145
 146         /* check them */
 147         dbuf = page_address(page);
 148         for (tmp = 0; tmp < qty; tmp++) {
 149                 if (dbuf->blocks[tmp].pagehdr.magic != AFS_DIR_MAGIC) {
 150                         printk("kAFS: %s(%lu): bad magic %d/%d is %04hx\n",
 151                                __FUNCTION__, dir->i_ino, tmp, qty,
 152                                ntohs(dbuf->blocks[tmp].pagehdr.magic));
 153                         goto error;
 154                 }
 155         }
 156
 157         SetPageChecked(page);
 158         return;
 159
 160  error:
 161         SetPageChecked(page);
 162         SetPageError(page);
 163
 164 } /* end afs_dir_check_page() */
 165
 166 /*****************************************************************************/
 167 /*
 168  * discard a page cached in the pagecache
 169  */
 170 static inline void afs_dir_put_page(struct page *page)
 171 {
 172         kunmap(page);
 173         page_cache_release(page);
 174
 175 } /* end afs_dir_put_page() */
 176
 177 /*****************************************************************************/
 178 /*
 179  * get a page into the pagecache
 180  */
 181 static struct page *afs_dir_get_page(struct inode *dir, unsigned long index)
 182 {
 183         struct page *page;
 184
 185         _enter("{%lu},%lu", dir->i_ino, index);
 186
 187         page = read_mapping_page(dir->i_mapping, index, NULL);
 188         if (!IS_ERR(page)) {
 189                 wait_on_page_locked(page);
 190                 kmap(page);
 191                 if (!PageUptodate(page))
 192                         goto fail;
 193                 if (!PageChecked(page))
 194                         afs_dir_check_page(dir, page);
 195                 if (PageError(page))
 196                         goto fail;
 197         }
 198         return page;
 199
 200  fail:
 201         afs_dir_put_page(page);
 202         return ERR_PTR(-EIO);
 203 } /* end afs_dir_get_page() */
 204
 205 /*****************************************************************************/
 206 /*
 207  * open an AFS directory file
 208  */
 209 static int afs_dir_open(struct inode *inode, struct file *file)
 210 {
 211         _enter("{%lu}", inode->i_ino);
 212
 213         BUILD_BUG_ON(sizeof(union afs_dir_block) != 2048);
 214         BUILD_BUG_ON(sizeof(union afs_dirent) != 32);
 215
 216         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED)
 217                 return -ENOENT;
 218
 219         _leave(" = 0");
 220         return 0;
 221
 222 } /* end afs_dir_open() */
 223
 224 /*****************************************************************************/
 225 /*
 226  * deal with one block in an AFS directory
 227  */
 228 static int afs_dir_iterate_block(unsigned *fpos,
 229                                  union afs_dir_block *block,
 230                                  unsigned blkoff,
 231                                  void *cookie,
 232                                  filldir_t filldir)
 233 {
 234         union afs_dirent *dire;
 235         unsigned offset, next, curr;
 236         size_t nlen;
 237         int tmp, ret;
 238
 239         _enter("%u,%x,%p,,",*fpos,blkoff,block);
 240
 241         curr = (*fpos - blkoff) / sizeof(union afs_dirent);
 242
 243         /* walk through the block, an entry at a time */
 244         for (offset = AFS_DIRENT_PER_BLOCK - block->pagehdr.nentries;
 245              offset < AFS_DIRENT_PER_BLOCK;
 246              offset = next
 247              ) {
 248                 next = offset + 1;
 249
 250                 /* skip entries marked unused in the bitmap */
 251                 if (!(block->pagehdr.bitmap[offset / 8] &
 252                       (1 << (offset % 8)))) {
 253                         _debug("ENT[%Zu.%u]: unused\n",
 254                                blkoff / sizeof(union afs_dir_block), offset);
 255                         if (offset >= curr)
 256                                 *fpos = blkoff +
 257                                         next * sizeof(union afs_dirent);
 258                         continue;
 259                 }
 260
 261                 /* got a valid entry */
 262                 dire = &block->dirents[offset];
 263                 nlen = strnlen(dire->u.name,
 264                                sizeof(*block) -
 265                                offset * sizeof(union afs_dirent));
 266
 267                 _debug("ENT[%Zu.%u]: %s %Zu \"%s\"\n",
 268                        blkoff / sizeof(union afs_dir_block), offset,
 269                        (offset < curr ? "skip" : "fill"),
 270                        nlen, dire->u.name);
 271
 272                 /* work out where the next possible entry is */
 273                 for (tmp = nlen; tmp > 15; tmp -= sizeof(union afs_dirent)) {
 274                         if (next >= AFS_DIRENT_PER_BLOCK) {
 275                                 _debug("ENT[%Zu.%u]:"
 276                                        " %u travelled beyond end dir block"
 277                                        " (len %u/%Zu)\n",
 278                                        blkoff / sizeof(union afs_dir_block),
 279                                        offset, next, tmp, nlen);
 280                                 return -EIO;
 281                         }
 282                         if (!(block->pagehdr.bitmap[next / 8] &
 283                               (1 << (next % 8)))) {
 284                                 _debug("ENT[%Zu.%u]:"
 285                                        " %u unmarked extension (len %u/%Zu)\n",
 286                                        blkoff / sizeof(union afs_dir_block),
 287                                        offset, next, tmp, nlen);
 288                                 return -EIO;
 289                         }
 290
 291                         _debug("ENT[%Zu.%u]: ext %u/%Zu\n",
 292                                blkoff / sizeof(union afs_dir_block),
 293                                next, tmp, nlen);
 294                         next++;
 295                 }
 296
 297                 /* skip if starts before the current position */
 298                 if (offset < curr)
 299                         continue;
 300
 301                 /* found the next entry */
 302                 ret = filldir(cookie,
 303                               dire->u.name,
 304                               nlen,
 305                               blkoff + offset * sizeof(union afs_dirent),
 306                               ntohl(dire->u.vnode),
 307                               filldir == afs_dir_lookup_filldir ?
 308                               ntohl(dire->u.unique) : DT_UNKNOWN);
 309                 if (ret < 0) {
 310                         _leave(" = 0 [full]");
 311                         return 0;
 312                 }
 313
 314                 *fpos = blkoff + next * sizeof(union afs_dirent);
 315         }
 316
 317         _leave(" = 1 [more]");
 318         return 1;
 319 } /* end afs_dir_iterate_block() */
 320
 321 /*****************************************************************************/
 322 /*
 323  * read an AFS directory
 324  */
 325 static int afs_dir_iterate(struct inode *dir, unsigned *fpos, void *cookie,
 326                            filldir_t filldir)
 327 {
 328         union afs_dir_block     *dblock;
 329         struct afs_dir_page *dbuf;
 330         struct page *page;
 331         unsigned blkoff, limit;
 332         int ret;
 333
 334         _enter("{%lu},%u,,", dir->i_ino, *fpos);
 335
 336         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 337                 _leave(" = -ESTALE");
 338                 return -ESTALE;
 339         }
 340
 341         /* round the file position up to the next entry boundary */
 342         *fpos += sizeof(union afs_dirent) - 1;
 343         *fpos &= ~(sizeof(union afs_dirent) - 1);
 344
 345         /* walk through the blocks in sequence */
 346         ret = 0;
 347         while (*fpos < dir->i_size) {
 348                 blkoff = *fpos & ~(sizeof(union afs_dir_block) - 1);
 349
 350                 /* fetch the appropriate page from the directory */
 351                 page = afs_dir_get_page(dir, blkoff / PAGE_SIZE);
 352                 if (IS_ERR(page)) {
 353                         ret = PTR_ERR(page);
 354                         break;
 355                 }
 356
 357                 limit = blkoff & ~(PAGE_SIZE - 1);
 358
 359                 dbuf = page_address(page);
 360
 361                 /* deal with the individual blocks stashed on this page */
 362                 do {
 363                         dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
 364                                                sizeof(union afs_dir_block)];
 365                         ret = afs_dir_iterate_block(fpos, dblock, blkoff,
 366                                                     cookie, filldir);
 367                         if (ret != 1) {
 368                                 afs_dir_put_page(page);
 369                                 goto out;
 370                         }
 371
 372                         blkoff += sizeof(union afs_dir_block);
 373
 374                 } while (*fpos < dir->i_size && blkoff < limit);
 375
 376                 afs_dir_put_page(page);
 377                 ret = 0;
 378         }
 379
 380  out:
 381         _leave(" = %d", ret);
 382         return ret;
 383 } /* end afs_dir_iterate() */
 384
 385 /*****************************************************************************/
 386 /*
 387  * read an AFS directory
 388  */
 389 static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
 390 {
 391         unsigned fpos;
 392         int ret;
 393
 394         _enter("{%Ld,{%lu}}", file->f_pos, file->f_path.dentry->d_inode->i_ino);
 395
 396         fpos = file->f_pos;
 397         ret = afs_dir_iterate(file->f_path.dentry->d_inode, &fpos, cookie, filldir);
 398         file->f_pos = fpos;
 399
 400         _leave(" = %d", ret);
 401         return ret;
 402 } /* end afs_dir_readdir() */
 403
 404 /*****************************************************************************/
 405 /*
 406  * search the directory for a name
 407  * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 408  *   uniquifier through dtype
 409  */
 410 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
 411                                   loff_t fpos, u64 ino, unsigned dtype)
 412 {
 413         struct afs_dir_lookup_cookie *cookie = _cookie;
 414
 415         _enter("{%s,%Zu},%s,%u,,%lu,%u",
 416                cookie->name, cookie->nlen, name, nlen, ino, dtype);
 417
 418         if (cookie->nlen != nlen || memcmp(cookie->name, name, nlen) != 0) {
 419                 _leave(" = 0 [no]");
 420                 return 0;
 421         }
 422
 423         cookie->fid.vnode = ino;
 424         cookie->fid.unique = dtype;
 425         cookie->found = 1;
 426
 427         _leave(" = -1 [found]");
 428         return -1;
 429 } /* end afs_dir_lookup_filldir() */
 430
 431 /*****************************************************************************/
 432 /*
 433  * look up an entry in a directory
 434  */
 435 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
 436                                      struct nameidata *nd)
 437 {
 438         struct afs_dir_lookup_cookie cookie;
 439         struct afs_super_info *as;
 440         struct afs_vnode *vnode;
 441         struct inode *inode;
 442         unsigned fpos;
 443         int ret;
 444
 445         _enter("{%lu},%p{%s}", dir->i_ino, dentry, dentry->d_name.name);
 446
 447         /* insanity checks first */
 448         BUILD_BUG_ON(sizeof(union afs_dir_block) != 2048);
 449         BUILD_BUG_ON(sizeof(union afs_dirent) != 32);
 450
 451         if (dentry->d_name.len > 255) {
 452                 _leave(" = -ENAMETOOLONG");
 453                 return ERR_PTR(-ENAMETOOLONG);
 454         }
 455
 456         vnode = AFS_FS_I(dir);
 457         if (vnode->flags & AFS_VNODE_DELETED) {
 458                 _leave(" = -ESTALE");
 459                 return ERR_PTR(-ESTALE);
 460         }
 461
 462         as = dir->i_sb->s_fs_info;
 463
 464         /* search the directory */
 465         cookie.name     = dentry->d_name.name;
 466         cookie.nlen     = dentry->d_name.len;
 467         cookie.fid.vid  = as->volume->vid;
 468         cookie.found    = 0;
 469
 470         fpos = 0;
 471         ret = afs_dir_iterate(dir, &fpos, &cookie, afs_dir_lookup_filldir);
 472         if (ret < 0) {
 473                 _leave(" = %d", ret);
 474                 return ERR_PTR(ret);
 475         }
 476
 477         ret = -ENOENT;
 478         if (!cookie.found) {
 479                 _leave(" = %d", ret);
 480                 return ERR_PTR(ret);
 481         }
 482
 483         /* instantiate the dentry */
 484         ret = afs_iget(dir->i_sb, &cookie.fid, &inode);
 485         if (ret < 0) {
 486                 _leave(" = %d", ret);
 487                 return ERR_PTR(ret);
 488         }
 489
 490         dentry->d_op = &afs_fs_dentry_operations;
 491         dentry->d_fsdata = (void *) (unsigned long) vnode->status.version;
 492
 493         d_add(dentry, inode);
 494         _leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
 495                cookie.fid.vnode,
 496                cookie.fid.unique,
 497                dentry->d_inode->i_ino,
 498                dentry->d_inode->i_version);
 499
 500         return NULL;
 501 } /* end afs_dir_lookup() */
 502
 503 /*****************************************************************************/
 504 /*
 505  * check that a dentry lookup hit has found a valid entry
 506  * - NOTE! the hit can be a negative hit too, so we can't assume we have an
 507  *   inode
 508  * (derived from nfs_lookup_revalidate)
 509  */
 510 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 511 {
 512         struct afs_dir_lookup_cookie cookie;
 513         struct dentry *parent;
 514         struct inode *inode, *dir;
 515         unsigned fpos;
 516         int ret;
 517
 518         _enter("{sb=%p n=%s},", dentry->d_sb, dentry->d_name.name);
 519
 520         /* lock down the parent dentry so we can peer at it */
 521         parent = dget_parent(dentry->d_parent);
 522
 523         dir = parent->d_inode;
 524         inode = dentry->d_inode;
 525
 526         /* handle a negative dentry */
 527         if (!inode)
 528                 goto out_bad;
 529
 530         /* handle a bad inode */
 531         if (is_bad_inode(inode)) {
 532                 printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
 533                        dentry->d_parent->d_name.name, dentry->d_name.name);
 534                 goto out_bad;
 535         }
 536
 537         /* force a full look up if the parent directory changed since last the
 538          * server was consulted
 539          * - otherwise this inode must still exist, even if the inode details
 540          *   themselves have changed
 541          */
 542         if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
 543                 afs_vnode_fetch_status(AFS_FS_I(dir));
 544
 545         if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
 546                 _debug("%s: parent dir deleted", dentry->d_name.name);
 547                 goto out_bad;
 548         }
 549
 550         if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
 551                 _debug("%s: file already deleted", dentry->d_name.name);
 552                 goto out_bad;
 553         }
 554
 555         if ((unsigned long) dentry->d_fsdata !=
 556             (unsigned long) AFS_FS_I(dir)->status.version) {
 557                 _debug("%s: parent changed %lu -> %u",
 558                        dentry->d_name.name,
 559                        (unsigned long) dentry->d_fsdata,
 560                        (unsigned) AFS_FS_I(dir)->status.version);
 561
 562                 /* search the directory for this vnode */
 563                 cookie.name     = dentry->d_name.name;
 564                 cookie.nlen     = dentry->d_name.len;
 565                 cookie.fid.vid  = AFS_FS_I(inode)->volume->vid;
 566                 cookie.found    = 0;
 567
 568                 fpos = 0;
 569                 ret = afs_dir_iterate(dir, &fpos, &cookie,
 570                                       afs_dir_lookup_filldir);
 571                 if (ret < 0) {
 572                         _debug("failed to iterate dir %s: %d",
 573                                parent->d_name.name, ret);
 574                         goto out_bad;
 575                 }
 576
 577                 if (!cookie.found) {
 578                         _debug("%s: dirent not found", dentry->d_name.name);
 579                         goto not_found;
 580                 }
 581
 582                 /* if the vnode ID has changed, then the dirent points to a
 583                  * different file */
 584                 if (cookie.fid.vnode != AFS_FS_I(inode)->fid.vnode) {
 585                         _debug("%s: dirent changed", dentry->d_name.name);
 586                         goto not_found;
 587                 }
 588
 589                 /* if the vnode ID uniqifier has changed, then the file has
 590                  * been deleted */
 591                 if (cookie.fid.unique != AFS_FS_I(inode)->fid.unique) {
 592                         _debug("%s: file deleted (uq %u -> %u I:%lu)",
 593                                dentry->d_name.name,
 594                                cookie.fid.unique,
 595                                AFS_FS_I(inode)->fid.unique,
 596                                inode->i_version);
 597                         spin_lock(&AFS_FS_I(inode)->lock);
 598                         AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
 599                         spin_unlock(&AFS_FS_I(inode)->lock);
 600                         invalidate_remote_inode(inode);
 601                         goto out_bad;
 602                 }
 603
 604                 dentry->d_fsdata =
 605                         (void *) (unsigned long) AFS_FS_I(dir)->status.version;
 606         }
 607
 608  out_valid:
 609         dput(parent);
 610         _leave(" = 1 [valid]");
 611         return 1;
 612
 613         /* the dirent, if it exists, now points to a different vnode */
 614  not_found:
 615         spin_lock(&dentry->d_lock);
 616         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 617         spin_unlock(&dentry->d_lock);
 618
 619  out_bad:
 620         if (inode) {
 621                 /* don't unhash if we have submounts */
 622                 if (have_submounts(dentry))
 623                         goto out_valid;
 624         }
 625
 626         shrink_dcache_parent(dentry);
 627
 628         _debug("dropping dentry %s/%s",
 629                dentry->d_parent->d_name.name, dentry->d_name.name);
 630         d_drop(dentry);
 631
 632         dput(parent);
 633
 634         _leave(" = 0 [bad]");
 635         return 0;
 636 } /* end afs_d_revalidate() */
 637
 638 /*****************************************************************************/
 639 /*
 640  * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 641  * sleep)
 642  * - called from dput() when d_count is going to 0.
 643  * - return 1 to request dentry be unhashed, 0 otherwise
 644  */
 645 static int afs_d_delete(struct dentry *dentry)
 646 {
 647         _enter("%s", dentry->d_name.name);
 648
 649         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 650                 goto zap;
 651
 652         if (dentry->d_inode) {
 653                 if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
 654                         goto zap;
 655         }
 656
 657         _leave(" = 0 [keep]");
 658         return 0;
 659
 660  zap:
 661         _leave(" = 1 [zap]");
 662         return 1;
 663 } /* end afs_d_delete() */