fs/overlayfs/readdir.c

   1 /*
   2  *
   3  * Copyright (C) 2011 Novell Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/slab.h>
  12 #include <linux/namei.h>
  13 #include <linux/file.h>
  14 #include <linux/xattr.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/security.h>
  17 #include <linux/cred.h>
  18 #include <linux/ratelimit.h>
  19 #include "overlayfs.h"
  20
  21 struct ovl_cache_entry {
  22         unsigned int len;
  23         unsigned int type;
  24         u64 real_ino;
  25         u64 ino;
  26         struct list_head l_node;
  27         struct rb_node node;
  28         struct ovl_cache_entry *next_maybe_whiteout;
  29         bool is_upper;
  30         bool is_whiteout;
  31         char name[];
  32 };
  33
  34 struct ovl_dir_cache {
  35         long refcount;
  36         u64 version;
  37         struct list_head entries;
  38         struct rb_root root;
  39 };
  40
  41 struct ovl_readdir_data {
  42         struct dir_context ctx;
  43         struct dentry *dentry;
  44         bool is_lowest;
  45         struct rb_root *root;
  46         struct list_head *list;
  47         struct list_head middle;
  48         struct ovl_cache_entry *first_maybe_whiteout;
  49         int count;
  50         int err;
  51         bool is_upper;
  52         bool d_type_supported;
  53 };
  54
  55 struct ovl_dir_file {
  56         bool is_real;
  57         bool is_upper;
  58         struct ovl_dir_cache *cache;
  59         struct list_head *cursor;
  60         struct file *realfile;
  61         struct file *upperfile;
  62 };
  63
  64 static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
  65 {
  66         return rb_entry(n, struct ovl_cache_entry, node);
  67 }
  68
  69 static bool ovl_cache_entry_find_link(const char *name, int len,
  70                                       struct rb_node ***link,
  71                                       struct rb_node **parent)
  72 {
  73         bool found = false;
  74         struct rb_node **newp = *link;
  75
  76         while (!found && *newp) {
  77                 int cmp;
  78                 struct ovl_cache_entry *tmp;
  79
  80                 *parent = *newp;
  81                 tmp = ovl_cache_entry_from_node(*newp);
  82                 cmp = strncmp(name, tmp->name, len);
  83                 if (cmp > 0)
  84                         newp = &tmp->node.rb_right;
  85                 else if (cmp < 0 || len < tmp->len)
  86                         newp = &tmp->node.rb_left;
  87                 else
  88                         found = true;
  89         }
  90         *link = newp;
  91
  92         return found;
  93 }
  94
  95 static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
  96                                                     const char *name, int len)
  97 {
  98         struct rb_node *node = root->rb_node;
  99         int cmp;
 100
 101         while (node) {
 102                 struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
 103
 104                 cmp = strncmp(name, p->name, len);
 105                 if (cmp > 0)
 106                         node = p->node.rb_right;
 107                 else if (cmp < 0 || len < p->len)
 108                         node = p->node.rb_left;
 109                 else
 110                         return p;
 111         }
 112
 113         return NULL;
 114 }
 115
 116 static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
 117                            struct ovl_cache_entry *p)
 118 {
 119         /* Don't care if not doing ovl_iter() */
 120         if (!rdd->dentry)
 121                 return false;
 122
 123         /* Always recalc d_ino when remapping lower inode numbers */
 124         if (ovl_xino_bits(rdd->dentry->d_sb))
 125                 return true;
 126
 127         /* Always recalc d_ino for parent */
 128         if (strcmp(p->name, "..") == 0)
 129                 return true;
 130
 131         /* If this is lower, then native d_ino will do */
 132         if (!rdd->is_upper)
 133                 return false;
 134
 135         /*
 136          * Recalc d_ino for '.' and for all entries if dir is impure (contains
 137          * copied up entries)
 138          */
 139         if ((p->name[0] == '.' && p->len == 1) ||
 140             ovl_test_flag(OVL_IMPURE, d_inode(rdd->dentry)))
 141                 return true;
 142
 143         return false;
 144 }
 145
 146 static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
 147                                                    const char *name, int len,
 148                                                    u64 ino, unsigned int d_type)
 149 {
 150         struct ovl_cache_entry *p;
 151         size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
 152
 153         p = kmalloc(size, GFP_KERNEL);
 154         if (!p)
 155                 return NULL;
 156
 157         memcpy(p->name, name, len);
 158         p->name[len] = '\0';
 159         p->len = len;
 160         p->type = d_type;
 161         p->real_ino = ino;
 162         p->ino = ino;
 163         /* Defer setting d_ino for upper entry to ovl_iterate() */
 164         if (ovl_calc_d_ino(rdd, p))
 165                 p->ino = 0;
 166         p->is_upper = rdd->is_upper;
 167         p->is_whiteout = false;
 168
 169         if (d_type == DT_CHR) {
 170                 p->next_maybe_whiteout = rdd->first_maybe_whiteout;
 171                 rdd->first_maybe_whiteout = p;
 172         }
 173         return p;
 174 }
 175
 176 static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
 177                                   const char *name, int len, u64 ino,
 178                                   unsigned int d_type)
 179 {
 180         struct rb_node **newp = &rdd->root->rb_node;
 181         struct rb_node *parent = NULL;
 182         struct ovl_cache_entry *p;
 183
 184         if (ovl_cache_entry_find_link(name, len, &newp, &parent))
 185                 return 0;
 186
 187         p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
 188         if (p == NULL) {
 189                 rdd->err = -ENOMEM;
 190                 return -ENOMEM;
 191         }
 192
 193         list_add_tail(&p->l_node, rdd->list);
 194         rb_link_node(&p->node, parent, newp);
 195         rb_insert_color(&p->node, rdd->root);
 196
 197         return 0;
 198 }
 199
 200 static int ovl_fill_lowest(struct ovl_readdir_data *rdd,
 201                            const char *name, int namelen,
 202                            loff_t offset, u64 ino, unsigned int d_type)
 203 {
 204         struct ovl_cache_entry *p;
 205
 206         p = ovl_cache_entry_find(rdd->root, name, namelen);
 207         if (p) {
 208                 list_move_tail(&p->l_node, &rdd->middle);
 209         } else {
 210                 p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
 211                 if (p == NULL)
 212                         rdd->err = -ENOMEM;
 213                 else
 214                         list_add_tail(&p->l_node, &rdd->middle);
 215         }
 216
 217         return rdd->err;
 218 }
 219
 220 void ovl_cache_free(struct list_head *list)
 221 {
 222         struct ovl_cache_entry *p;
 223         struct ovl_cache_entry *n;
 224
 225         list_for_each_entry_safe(p, n, list, l_node)
 226                 kfree(p);
 227
 228         INIT_LIST_HEAD(list);
 229 }
 230
 231 void ovl_dir_cache_free(struct inode *inode)
 232 {
 233         struct ovl_dir_cache *cache = ovl_dir_cache(inode);
 234
 235         if (cache) {
 236                 ovl_cache_free(&cache->entries);
 237                 kfree(cache);
 238         }
 239 }
 240
 241 static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
 242 {
 243         struct ovl_dir_cache *cache = od->cache;
 244
 245         WARN_ON(cache->refcount <= 0);
 246         cache->refcount--;
 247         if (!cache->refcount) {
 248                 if (ovl_dir_cache(d_inode(dentry)) == cache)
 249                         ovl_set_dir_cache(d_inode(dentry), NULL);
 250
 251                 ovl_cache_free(&cache->entries);
 252                 kfree(cache);
 253         }
 254 }
 255
 256 static int ovl_fill_merge(struct dir_context *ctx, const char *name,
 257                           int namelen, loff_t offset, u64 ino,
 258                           unsigned int d_type)
 259 {
 260         struct ovl_readdir_data *rdd =
 261                 container_of(ctx, struct ovl_readdir_data, ctx);
 262
 263         rdd->count++;
 264         if (!rdd->is_lowest)
 265                 return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
 266         else
 267                 return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
 268 }
 269
 270 static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
 271 {
 272         int err;
 273         struct ovl_cache_entry *p;
 274         struct dentry *dentry;
 275         const struct cred *old_cred;
 276
 277         old_cred = ovl_override_creds(rdd->dentry->d_sb);
 278
 279         err = down_write_killable(&dir->d_inode->i_rwsem);
 280         if (!err) {
 281                 while (rdd->first_maybe_whiteout) {
 282                         p = rdd->first_maybe_whiteout;
 283                         rdd->first_maybe_whiteout = p->next_maybe_whiteout;
 284                         dentry = lookup_one_len(p->name, dir, p->len);
 285                         if (!IS_ERR(dentry)) {
 286                                 p->is_whiteout = ovl_is_whiteout(dentry);
 287                                 dput(dentry);
 288                         }
 289                 }
 290                 inode_unlock(dir->d_inode);
 291         }
 292         revert_creds(old_cred);
 293
 294         return err;
 295 }
 296
 297 static inline int ovl_dir_read(struct path *realpath,
 298                                struct ovl_readdir_data *rdd)
 299 {
 300         struct file *realfile;
 301         int err;
 302
 303         realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
 304         if (IS_ERR(realfile))
 305                 return PTR_ERR(realfile);
 306
 307         rdd->first_maybe_whiteout = NULL;
 308         rdd->ctx.pos = 0;
 309         do {
 310                 rdd->count = 0;
 311                 rdd->err = 0;
 312                 err = iterate_dir(realfile, &rdd->ctx);
 313                 if (err >= 0)
 314                         err = rdd->err;
 315         } while (!err && rdd->count);
 316
 317         if (!err && rdd->first_maybe_whiteout && rdd->dentry)
 318                 err = ovl_check_whiteouts(realpath->dentry, rdd);
 319
 320         fput(realfile);
 321
 322         return err;
 323 }
 324
 325 /*
 326  * Can we iterate real dir directly?
 327  *
 328  * Non-merge dir may contain whiteouts from a time it was a merge upper, before
 329  * lower dir was removed under it and possibly before it was rotated from upper
 330  * to lower layer.
 331  */
 332 static bool ovl_dir_is_real(struct dentry *dir)
 333 {
 334         return !ovl_test_flag(OVL_WHITEOUTS, d_inode(dir));
 335 }
 336
 337 static void ovl_dir_reset(struct file *file)
 338 {
 339         struct ovl_dir_file *od = file->private_data;
 340         struct ovl_dir_cache *cache = od->cache;
 341         struct dentry *dentry = file->f_path.dentry;
 342         bool is_real;
 343
 344         if (cache && ovl_dentry_version_get(dentry) != cache->version) {
 345                 ovl_cache_put(od, dentry);
 346                 od->cache = NULL;
 347                 od->cursor = NULL;
 348         }
 349         is_real = ovl_dir_is_real(dentry);
 350         if (od->is_real != is_real) {
 351                 /* is_real can only become false when dir is copied up */
 352                 if (WARN_ON(is_real))
 353                         return;
 354                 od->is_real = false;
 355         }
 356 }
 357
 358 static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list,
 359         struct rb_root *root)
 360 {
 361         int err;
 362         struct path realpath;
 363         struct ovl_readdir_data rdd = {
 364                 .ctx.actor = ovl_fill_merge,
 365                 .dentry = dentry,
 366                 .list = list,
 367                 .root = root,
 368                 .is_lowest = false,
 369         };
 370         int idx, next;
 371
 372         for (idx = 0; idx != -1; idx = next) {
 373                 next = ovl_path_next(idx, dentry, &realpath);
 374                 rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry;
 375
 376                 if (next != -1) {
 377                         err = ovl_dir_read(&realpath, &rdd);
 378                         if (err)
 379                                 break;
 380                 } else {
 381                         /*
 382                          * Insert lowest layer entries before upper ones, this
 383                          * allows offsets to be reasonably constant
 384                          */
 385                         list_add(&rdd.middle, rdd.list);
 386                         rdd.is_lowest = true;
 387                         err = ovl_dir_read(&realpath, &rdd);
 388                         list_del(&rdd.middle);
 389                 }
 390         }
 391         return err;
 392 }
 393
 394 static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
 395 {
 396         struct list_head *p;
 397         loff_t off = 0;
 398
 399         list_for_each(p, &od->cache->entries) {
 400                 if (off >= pos)
 401                         break;
 402                 off++;
 403         }
 404         /* Cursor is safe since the cache is stable */
 405         od->cursor = p;
 406 }
 407
 408 static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
 409 {
 410         int res;
 411         struct ovl_dir_cache *cache;
 412
 413         cache = ovl_dir_cache(d_inode(dentry));
 414         if (cache && ovl_dentry_version_get(dentry) == cache->version) {
 415                 WARN_ON(!cache->refcount);
 416                 cache->refcount++;
 417                 return cache;
 418         }
 419         ovl_set_dir_cache(d_inode(dentry), NULL);
 420
 421         cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
 422         if (!cache)
 423                 return ERR_PTR(-ENOMEM);
 424
 425         cache->refcount = 1;
 426         INIT_LIST_HEAD(&cache->entries);
 427         cache->root = RB_ROOT;
 428
 429         res = ovl_dir_read_merged(dentry, &cache->entries, &cache->root);
 430         if (res) {
 431                 ovl_cache_free(&cache->entries);
 432                 kfree(cache);
 433                 return ERR_PTR(res);
 434         }
 435
 436         cache->version = ovl_dentry_version_get(dentry);
 437         ovl_set_dir_cache(d_inode(dentry), cache);
 438
 439         return cache;
 440 }
 441
 442 /* Map inode number to lower fs unique range */
 443 static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
 444                                const char *name, int namelen)
 445 {
 446         if (ino >> (64 - xinobits)) {
 447                 pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
 448                                     namelen, name, ino, xinobits);
 449                 return ino;
 450         }
 451
 452         return ino | ((u64)fsid) << (64 - xinobits);
 453 }
 454
 455 /*
 456  * Set d_ino for upper entries. Non-upper entries should always report
 457  * the uppermost real inode ino and should not call this function.
 458  *
 459  * When not all layer are on same fs, report real ino also for upper.
 460  *
 461  * When all layers are on the same fs, and upper has a reference to
 462  * copy up origin, call vfs_getattr() on the overlay entry to make
 463  * sure that d_ino will be consistent with st_ino from stat(2).
 464  */
 465 static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
 466
 467 {
 468         struct dentry *dir = path->dentry;
 469         struct dentry *this = NULL;
 470         enum ovl_path_type type;
 471         u64 ino = p->real_ino;
 472         int xinobits = ovl_xino_bits(dir->d_sb);
 473         int err = 0;
 474
 475         if (!ovl_same_sb(dir->d_sb) && !xinobits)
 476                 goto out;
 477
 478         if (p->name[0] == '.') {
 479                 if (p->len == 1) {
 480                         this = dget(dir);
 481                         goto get;
 482                 }
 483                 if (p->len == 2 && p->name[1] == '.') {
 484                         /* we shall not be moved */
 485                         this = dget(dir->d_parent);
 486                         goto get;
 487                 }
 488         }
 489         this = lookup_one_len(p->name, dir, p->len);
 490         if (IS_ERR_OR_NULL(this) || !this->d_inode) {
 491                 if (IS_ERR(this)) {
 492                         err = PTR_ERR(this);
 493                         this = NULL;
 494                         goto fail;
 495                 }
 496                 goto out;
 497         }
 498
 499 get:
 500         type = ovl_path_type(this);
 501         if (OVL_TYPE_ORIGIN(type)) {
 502                 struct kstat stat;
 503                 struct path statpath = *path;
 504
 505                 statpath.dentry = this;
 506                 err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
 507                 if (err)
 508                         goto fail;
 509
 510                 WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
 511                 ino = stat.ino;
 512         } else if (xinobits && !OVL_TYPE_UPPER(type)) {
 513                 ino = ovl_remap_lower_ino(ino, xinobits,
 514                                           ovl_layer_lower(this)->fsid,
 515                                           p->name, p->len);
 516         }
 517
 518 out:
 519         p->ino = ino;
 520         dput(this);
 521         return err;
 522
 523 fail:
 524         pr_warn_ratelimited("overlayfs: failed to look up (%s) for ino (%i)\n",
 525                             p->name, err);
 526         goto out;
 527 }
 528
 529 static int ovl_fill_plain(struct dir_context *ctx, const char *name,
 530                           int namelen, loff_t offset, u64 ino,
 531                           unsigned int d_type)
 532 {
 533         struct ovl_cache_entry *p;
 534         struct ovl_readdir_data *rdd =
 535                 container_of(ctx, struct ovl_readdir_data, ctx);
 536
 537         rdd->count++;
 538         p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
 539         if (p == NULL) {
 540                 rdd->err = -ENOMEM;
 541                 return -ENOMEM;
 542         }
 543         list_add_tail(&p->l_node, rdd->list);
 544
 545         return 0;
 546 }
 547
 548 static int ovl_dir_read_impure(struct path *path,  struct list_head *list,
 549                                struct rb_root *root)
 550 {
 551         int err;
 552         struct path realpath;
 553         struct ovl_cache_entry *p, *n;
 554         struct ovl_readdir_data rdd = {
 555                 .ctx.actor = ovl_fill_plain,
 556                 .list = list,
 557                 .root = root,
 558         };
 559
 560         INIT_LIST_HEAD(list);
 561         *root = RB_ROOT;
 562         ovl_path_upper(path->dentry, &realpath);
 563
 564         err = ovl_dir_read(&realpath, &rdd);
 565         if (err)
 566                 return err;
 567
 568         list_for_each_entry_safe(p, n, list, l_node) {
 569                 if (strcmp(p->name, ".") != 0 &&
 570                     strcmp(p->name, "..") != 0) {
 571                         err = ovl_cache_update_ino(path, p);
 572                         if (err)
 573                                 return err;
 574                 }
 575                 if (p->ino == p->real_ino) {
 576                         list_del(&p->l_node);
 577                         kfree(p);
 578                 } else {
 579                         struct rb_node **newp = &root->rb_node;
 580                         struct rb_node *parent = NULL;
 581
 582                         if (WARN_ON(ovl_cache_entry_find_link(p->name, p->len,
 583                                                               &newp, &parent)))
 584                                 return -EIO;
 585
 586                         rb_link_node(&p->node, parent, newp);
 587                         rb_insert_color(&p->node, root);
 588                 }
 589         }
 590         return 0;
 591 }
 592
 593 static struct ovl_dir_cache *ovl_cache_get_impure(struct path *path)
 594 {
 595         int res;
 596         struct dentry *dentry = path->dentry;
 597         struct ovl_dir_cache *cache;
 598
 599         cache = ovl_dir_cache(d_inode(dentry));
 600         if (cache && ovl_dentry_version_get(dentry) == cache->version)
 601                 return cache;
 602
 603         /* Impure cache is not refcounted, free it here */
 604         ovl_dir_cache_free(d_inode(dentry));
 605         ovl_set_dir_cache(d_inode(dentry), NULL);
 606
 607         cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
 608         if (!cache)
 609                 return ERR_PTR(-ENOMEM);
 610
 611         res = ovl_dir_read_impure(path, &cache->entries, &cache->root);
 612         if (res) {
 613                 ovl_cache_free(&cache->entries);
 614                 kfree(cache);
 615                 return ERR_PTR(res);
 616         }
 617         if (list_empty(&cache->entries)) {
 618                 /*
 619                  * A good opportunity to get rid of an unneeded "impure" flag.
 620                  * Removing the "impure" xattr is best effort.
 621                  */
 622                 if (!ovl_want_write(dentry)) {
 623                         ovl_do_removexattr(ovl_dentry_upper(dentry),
 624                                            OVL_XATTR_IMPURE);
 625                         ovl_drop_write(dentry);
 626                 }
 627                 ovl_clear_flag(OVL_IMPURE, d_inode(dentry));
 628                 kfree(cache);
 629                 return NULL;
 630         }
 631
 632         cache->version = ovl_dentry_version_get(dentry);
 633         ovl_set_dir_cache(d_inode(dentry), cache);
 634
 635         return cache;
 636 }
 637
 638 struct ovl_readdir_translate {
 639         struct dir_context *orig_ctx;
 640         struct ovl_dir_cache *cache;
 641         struct dir_context ctx;
 642         u64 parent_ino;
 643         int fsid;
 644         int xinobits;
 645 };
 646
 647 static int ovl_fill_real(struct dir_context *ctx, const char *name,
 648                            int namelen, loff_t offset, u64 ino,
 649                            unsigned int d_type)
 650 {
 651         struct ovl_readdir_translate *rdt =
 652                 container_of(ctx, struct ovl_readdir_translate, ctx);
 653         struct dir_context *orig_ctx = rdt->orig_ctx;
 654
 655         if (rdt->parent_ino && strcmp(name, "..") == 0) {
 656                 ino = rdt->parent_ino;
 657         } else if (rdt->cache) {
 658                 struct ovl_cache_entry *p;
 659
 660                 p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
 661                 if (p)
 662                         ino = p->ino;
 663         } else if (rdt->xinobits) {
 664                 ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
 665                                           name, namelen);
 666         }
 667
 668         return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
 669 }
 670
 671 static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
 672 {
 673         int err;
 674         struct ovl_dir_file *od = file->private_data;
 675         struct dentry *dir = file->f_path.dentry;
 676         struct ovl_layer *lower_layer = ovl_layer_lower(dir);
 677         struct ovl_readdir_translate rdt = {
 678                 .ctx.actor = ovl_fill_real,
 679                 .orig_ctx = ctx,
 680                 .xinobits = ovl_xino_bits(dir->d_sb),
 681         };
 682
 683         if (rdt.xinobits && lower_layer)
 684                 rdt.fsid = lower_layer->fsid;
 685
 686         if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
 687                 struct kstat stat;
 688                 struct path statpath = file->f_path;
 689
 690                 statpath.dentry = dir->d_parent;
 691                 err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
 692                 if (err)
 693                         return err;
 694
 695                 WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
 696                 rdt.parent_ino = stat.ino;
 697         }
 698
 699         if (ovl_test_flag(OVL_IMPURE, d_inode(dir))) {
 700                 rdt.cache = ovl_cache_get_impure(&file->f_path);
 701                 if (IS_ERR(rdt.cache))
 702                         return PTR_ERR(rdt.cache);
 703         }
 704
 705         err = iterate_dir(od->realfile, &rdt.ctx);
 706         ctx->pos = rdt.ctx.pos;
 707
 708         return err;
 709 }
 710
 711
 712 static int ovl_iterate(struct file *file, struct dir_context *ctx)
 713 {
 714         struct ovl_dir_file *od = file->private_data;
 715         struct dentry *dentry = file->f_path.dentry;
 716         struct ovl_cache_entry *p;
 717         int err;
 718
 719         if (!ctx->pos)
 720                 ovl_dir_reset(file);
 721
 722         if (od->is_real) {
 723                 /*
 724                  * If parent is merge, then need to adjust d_ino for '..', if
 725                  * dir is impure then need to adjust d_ino for copied up
 726                  * entries.
 727                  */
 728                 if (ovl_xino_bits(dentry->d_sb) ||
 729                     (ovl_same_sb(dentry->d_sb) &&
 730                      (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
 731                       OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
 732                         return ovl_iterate_real(file, ctx);
 733                 }
 734                 return iterate_dir(od->realfile, ctx);
 735         }
 736
 737         if (!od->cache) {
 738                 struct ovl_dir_cache *cache;
 739
 740                 cache = ovl_cache_get(dentry);
 741                 if (IS_ERR(cache))
 742                         return PTR_ERR(cache);
 743
 744                 od->cache = cache;
 745                 ovl_seek_cursor(od, ctx->pos);
 746         }
 747
 748         while (od->cursor != &od->cache->entries) {
 749                 p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
 750                 if (!p->is_whiteout) {
 751                         if (!p->ino) {
 752                                 err = ovl_cache_update_ino(&file->f_path, p);
 753                                 if (err)
 754                                         return err;
 755                         }
 756                         if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
 757                                 break;
 758                 }
 759                 od->cursor = p->l_node.next;
 760                 ctx->pos++;
 761         }
 762         return 0;
 763 }
 764
 765 static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
 766 {
 767         loff_t res;
 768         struct ovl_dir_file *od = file->private_data;
 769
 770         inode_lock(file_inode(file));
 771         if (!file->f_pos)
 772                 ovl_dir_reset(file);
 773
 774         if (od->is_real) {
 775                 res = vfs_llseek(od->realfile, offset, origin);
 776                 file->f_pos = od->realfile->f_pos;
 777         } else {
 778                 res = -EINVAL;
 779
 780                 switch (origin) {
 781                 case SEEK_CUR:
 782                         offset += file->f_pos;
 783                         break;
 784                 case SEEK_SET:
 785                         break;
 786                 default:
 787                         goto out_unlock;
 788                 }
 789                 if (offset < 0)
 790                         goto out_unlock;
 791
 792                 if (offset != file->f_pos) {
 793                         file->f_pos = offset;
 794                         if (od->cache)
 795                                 ovl_seek_cursor(od, offset);
 796                 }
 797                 res = offset;
 798         }
 799 out_unlock:
 800         inode_unlock(file_inode(file));
 801
 802         return res;
 803 }
 804
 805 static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
 806                          int datasync)
 807 {
 808         struct ovl_dir_file *od = file->private_data;
 809         struct dentry *dentry = file->f_path.dentry;
 810         struct file *realfile = od->realfile;
 811
 812         /* Nothing to sync for lower */
 813         if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
 814                 return 0;
 815
 816         /*
 817          * Need to check if we started out being a lower dir, but got copied up
 818          */
 819         if (!od->is_upper) {
 820                 struct inode *inode = file_inode(file);
 821
 822                 realfile = READ_ONCE(od->upperfile);
 823                 if (!realfile) {
 824                         struct path upperpath;
 825
 826                         ovl_path_upper(dentry, &upperpath);
 827                         realfile = ovl_path_open(&upperpath, O_RDONLY);
 828
 829                         inode_lock(inode);
 830                         if (!od->upperfile) {
 831                                 if (IS_ERR(realfile)) {
 832                                         inode_unlock(inode);
 833                                         return PTR_ERR(realfile);
 834                                 }
 835                                 smp_store_release(&od->upperfile, realfile);
 836                         } else {
 837                                 /* somebody has beaten us to it */
 838                                 if (!IS_ERR(realfile))
 839                                         fput(realfile);
 840                                 realfile = od->upperfile;
 841                         }
 842                         inode_unlock(inode);
 843                 }
 844         }
 845
 846         return vfs_fsync_range(realfile, start, end, datasync);
 847 }
 848
 849 static int ovl_dir_release(struct inode *inode, struct file *file)
 850 {
 851         struct ovl_dir_file *od = file->private_data;
 852
 853         if (od->cache) {
 854                 inode_lock(inode);
 855                 ovl_cache_put(od, file->f_path.dentry);
 856                 inode_unlock(inode);
 857         }
 858         fput(od->realfile);
 859         if (od->upperfile)
 860                 fput(od->upperfile);
 861         kfree(od);
 862
 863         return 0;
 864 }
 865
 866 static int ovl_dir_open(struct inode *inode, struct file *file)
 867 {
 868         struct path realpath;
 869         struct file *realfile;
 870         struct ovl_dir_file *od;
 871         enum ovl_path_type type;
 872
 873         od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
 874         if (!od)
 875                 return -ENOMEM;
 876
 877         type = ovl_path_real(file->f_path.dentry, &realpath);
 878         realfile = ovl_path_open(&realpath, file->f_flags);
 879         if (IS_ERR(realfile)) {
 880                 kfree(od);
 881                 return PTR_ERR(realfile);
 882         }
 883         od->realfile = realfile;
 884         od->is_real = ovl_dir_is_real(file->f_path.dentry);
 885         od->is_upper = OVL_TYPE_UPPER(type);
 886         file->private_data = od;
 887
 888         return 0;
 889 }
 890
 891 const struct file_operations ovl_dir_operations = {
 892         .read           = generic_read_dir,
 893         .open           = ovl_dir_open,
 894         .iterate        = ovl_iterate,
 895         .llseek         = ovl_dir_llseek,
 896         .fsync          = ovl_dir_fsync,
 897         .release        = ovl_dir_release,
 898 };
 899
 900 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
 901 {
 902         int err;
 903         struct ovl_cache_entry *p, *n;
 904         struct rb_root root = RB_ROOT;
 905         const struct cred *old_cred;
 906
 907         old_cred = ovl_override_creds(dentry->d_sb);
 908         err = ovl_dir_read_merged(dentry, list, &root);
 909         revert_creds(old_cred);
 910         if (err)
 911                 return err;
 912
 913         err = 0;
 914
 915         list_for_each_entry_safe(p, n, list, l_node) {
 916                 /*
 917                  * Select whiteouts in upperdir, they should
 918                  * be cleared when deleting this directory.
 919                  */
 920                 if (p->is_whiteout) {
 921                         if (p->is_upper)
 922                                 continue;
 923                         goto del_entry;
 924                 }
 925
 926                 if (p->name[0] == '.') {
 927                         if (p->len == 1)
 928                                 goto del_entry;
 929                         if (p->len == 2 && p->name[1] == '.')
 930                                 goto del_entry;
 931                 }
 932                 err = -ENOTEMPTY;
 933                 break;
 934
 935 del_entry:
 936                 list_del(&p->l_node);
 937                 kfree(p);
 938         }
 939
 940         return err;
 941 }
 942
 943 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
 944 {
 945         struct ovl_cache_entry *p;
 946
 947         inode_lock_nested(upper->d_inode, I_MUTEX_CHILD);
 948         list_for_each_entry(p, list, l_node) {
 949                 struct dentry *dentry;
 950
 951                 if (WARN_ON(!p->is_whiteout || !p->is_upper))
 952                         continue;
 953
 954                 dentry = lookup_one_len(p->name, upper, p->len);
 955                 if (IS_ERR(dentry)) {
 956                         pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
 957                                upper->d_name.name, p->len, p->name,
 958                                (int) PTR_ERR(dentry));
 959                         continue;
 960                 }
 961                 if (dentry->d_inode)
 962                         ovl_cleanup(upper->d_inode, dentry);
 963                 dput(dentry);
 964         }
 965         inode_unlock(upper->d_inode);
 966 }
 967
 968 static int ovl_check_d_type(struct dir_context *ctx, const char *name,
 969                           int namelen, loff_t offset, u64 ino,
 970                           unsigned int d_type)
 971 {
 972         struct ovl_readdir_data *rdd =
 973                 container_of(ctx, struct ovl_readdir_data, ctx);
 974
 975         /* Even if d_type is not supported, DT_DIR is returned for . and .. */
 976         if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
 977                 return 0;
 978
 979         if (d_type != DT_UNKNOWN)
 980                 rdd->d_type_supported = true;
 981
 982         return 0;
 983 }
 984
 985 /*
 986  * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
 987  * if error is encountered.
 988  */
 989 int ovl_check_d_type_supported(struct path *realpath)
 990 {
 991         int err;
 992         struct ovl_readdir_data rdd = {
 993                 .ctx.actor = ovl_check_d_type,
 994                 .d_type_supported = false,
 995         };
 996
 997         err = ovl_dir_read(realpath, &rdd);
 998         if (err)
 999                 return err;
1000
1001         return rdd.d_type_supported;
1002 }
1003
1004 static void ovl_workdir_cleanup_recurse(struct path *path, int level)
1005 {
1006         int err;
1007         struct inode *dir = path->dentry->d_inode;
1008         LIST_HEAD(list);
1009         struct rb_root root = RB_ROOT;
1010         struct ovl_cache_entry *p;
1011         struct ovl_readdir_data rdd = {
1012                 .ctx.actor = ovl_fill_merge,
1013                 .dentry = NULL,
1014                 .list = &list,
1015                 .root = &root,
1016                 .is_lowest = false,
1017         };
1018
1019         err = ovl_dir_read(path, &rdd);
1020         if (err)
1021                 goto out;
1022
1023         inode_lock_nested(dir, I_MUTEX_PARENT);
1024         list_for_each_entry(p, &list, l_node) {
1025                 struct dentry *dentry;
1026
1027                 if (p->name[0] == '.') {
1028                         if (p->len == 1)
1029                                 continue;
1030                         if (p->len == 2 && p->name[1] == '.')
1031                                 continue;
1032                 }
1033                 dentry = lookup_one_len(p->name, path->dentry, p->len);
1034                 if (IS_ERR(dentry))
1035                         continue;
1036                 if (dentry->d_inode)
1037                         ovl_workdir_cleanup(dir, path->mnt, dentry, level);
1038                 dput(dentry);
1039         }
1040         inode_unlock(dir);
1041 out:
1042         ovl_cache_free(&list);
1043 }
1044
1045 void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
1046                          struct dentry *dentry, int level)
1047 {
1048         int err;
1049
1050         if (!d_is_dir(dentry) || level > 1) {
1051                 ovl_cleanup(dir, dentry);
1052                 return;
1053         }
1054
1055         err = ovl_do_rmdir(dir, dentry);
1056         if (err) {
1057                 struct path path = { .mnt = mnt, .dentry = dentry };
1058
1059                 inode_unlock(dir);
1060                 ovl_workdir_cleanup_recurse(&path, level + 1);
1061                 inode_lock_nested(dir, I_MUTEX_PARENT);
1062                 ovl_cleanup(dir, dentry);
1063         }
1064 }
1065
1066 int ovl_indexdir_cleanup(struct ovl_fs *ofs)
1067 {
1068         int err;
1069         struct dentry *indexdir = ofs->indexdir;
1070         struct dentry *index = NULL;
1071         struct inode *dir = indexdir->d_inode;
1072         struct path path = { .mnt = ofs->upper_mnt, .dentry = indexdir };
1073         LIST_HEAD(list);
1074         struct rb_root root = RB_ROOT;
1075         struct ovl_cache_entry *p;
1076         struct ovl_readdir_data rdd = {
1077                 .ctx.actor = ovl_fill_merge,
1078                 .dentry = NULL,
1079                 .list = &list,
1080                 .root = &root,
1081                 .is_lowest = false,
1082         };
1083
1084         err = ovl_dir_read(&path, &rdd);
1085         if (err)
1086                 goto out;
1087
1088         inode_lock_nested(dir, I_MUTEX_PARENT);
1089         list_for_each_entry(p, &list, l_node) {
1090                 if (p->name[0] == '.') {
1091                         if (p->len == 1)
1092                                 continue;
1093                         if (p->len == 2 && p->name[1] == '.')
1094                                 continue;
1095                 }
1096                 index = lookup_one_len(p->name, indexdir, p->len);
1097                 if (IS_ERR(index)) {
1098                         err = PTR_ERR(index);
1099                         index = NULL;
1100                         break;
1101                 }
1102                 err = ovl_verify_index(ofs, index);
1103                 if (!err) {
1104                         goto next;
1105                 } else if (err == -ESTALE) {
1106                         /* Cleanup stale index entries */
1107                         err = ovl_cleanup(dir, index);
1108                 } else if (err != -ENOENT) {
1109                         /*
1110                          * Abort mount to avoid corrupting the index if
1111                          * an incompatible index entry was found or on out
1112                          * of memory.
1113                          */
1114                         break;
1115                 } else if (ofs->config.nfs_export) {
1116                         /*
1117                          * Whiteout orphan index to block future open by
1118                          * handle after overlay nlink dropped to zero.
1119                          */
1120                         err = ovl_cleanup_and_whiteout(indexdir, dir, index);
1121                 } else {
1122                         /* Cleanup orphan index entries */
1123                         err = ovl_cleanup(dir, index);
1124                 }
1125
1126                 if (err)
1127                         break;
1128
1129 next:
1130                 dput(index);
1131                 index = NULL;
1132         }
1133         dput(index);
1134         inode_unlock(dir);
1135 out:
1136         ovl_cache_free(&list);
1137         if (err)
1138                 pr_err("overlayfs: failed index dir cleanup (%i)\n", err);
1139         return err;
1140 }