git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/dirent.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_methods.h"
   5 #include "btree_update.h"
   6 #include "extents.h"
   7 #include "dirent.h"
   8 #include "fs.h"
   9 #include "keylist.h"
  10 #include "str_hash.h"
  11 #include "subvolume.h"
  12
  13 #include <linux/dcache.h>
  14
  15 unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  16 {
  17         unsigned len = bkey_val_bytes(d.k) -
  18                 offsetof(struct bch_dirent, d_name);
  19
  20         return strnlen(d.v->d_name, len);
  21 }
  22
  23 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  24                             const struct qstr *name)
  25 {
  26         struct bch_str_hash_ctx ctx;
  27
  28         bch2_str_hash_init(&ctx, info);
  29         bch2_str_hash_update(&ctx, info, name->name, name->len);
  30
  31         /* [0,2) reserved for dots */
  32         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  33 }
  34
  35 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  36 {
  37         return bch2_dirent_hash(info, key);
  38 }
  39
  40 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  41 {
  42         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  43         struct qstr name = QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  44
  45         return bch2_dirent_hash(info, &name);
  46 }
  47
  48 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  49 {
  50         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  51         int len = bch2_dirent_name_bytes(l);
  52         const struct qstr *r = _r;
  53
  54         return len - r->len ?: memcmp(l.v->d_name, r->name, len);
  55 }
  56
  57 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  58 {
  59         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  60         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  61         int l_len = bch2_dirent_name_bytes(l);
  62         int r_len = bch2_dirent_name_bytes(r);
  63
  64         return l_len - r_len ?: memcmp(l.v->d_name, r.v->d_name, l_len);
  65 }
  66
  67 static bool dirent_is_visible(subvol_inum inum, struct bkey_s_c k)
  68 {
  69         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  70
  71         if (d.v->d_type == DT_SUBVOL)
  72                 return le32_to_cpu(d.v->d_parent_subvol) == inum.subvol;
  73         return true;
  74 }
  75
  76 const struct bch_hash_desc bch2_dirent_hash_desc = {
  77         .btree_id       = BTREE_ID_dirents,
  78         .key_type       = KEY_TYPE_dirent,
  79         .hash_key       = dirent_hash_key,
  80         .hash_bkey      = dirent_hash_bkey,
  81         .cmp_key        = dirent_cmp_key,
  82         .cmp_bkey       = dirent_cmp_bkey,
  83         .is_visible     = dirent_is_visible,
  84 };
  85
  86 int bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k,
  87                         unsigned flags, struct printbuf *err)
  88 {
  89         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  90         unsigned len;
  91
  92         len = bch2_dirent_name_bytes(d);
  93         if (!len) {
  94                 prt_printf(err, "empty name");
  95                 return -BCH_ERR_invalid_bkey;
  96         }
  97
  98         if (bkey_val_u64s(k.k) > dirent_val_u64s(len)) {
  99                 prt_printf(err, "value too big (%zu > %u)",
 100                        bkey_val_u64s(k.k), dirent_val_u64s(len));
 101                 return -BCH_ERR_invalid_bkey;
 102         }
 103
 104         if (len > BCH_NAME_MAX) {
 105                 prt_printf(err, "dirent name too big (%u > %u)",
 106                        len, BCH_NAME_MAX);
 107                 return -BCH_ERR_invalid_bkey;
 108         }
 109
 110         if (len == 1 && !memcmp(d.v->d_name, ".", 1)) {
 111                 prt_printf(err, "invalid name");
 112                 return -BCH_ERR_invalid_bkey;
 113         }
 114
 115         if (len == 2 && !memcmp(d.v->d_name, "..", 2)) {
 116                 prt_printf(err, "invalid name");
 117                 return -BCH_ERR_invalid_bkey;
 118         }
 119
 120         if (memchr(d.v->d_name, '/', len)) {
 121                 prt_printf(err, "invalid name");
 122                 return -BCH_ERR_invalid_bkey;
 123         }
 124
 125         if (d.v->d_type != DT_SUBVOL &&
 126             le64_to_cpu(d.v->d_inum) == d.k->p.inode) {
 127                 prt_printf(err, "dirent points to own directory");
 128                 return -BCH_ERR_invalid_bkey;
 129         }
 130
 131         return 0;
 132 }
 133
 134 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 135                          struct bkey_s_c k)
 136 {
 137         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 138
 139         prt_printf(out, "%.*s -> %llu type %s",
 140                bch2_dirent_name_bytes(d),
 141                d.v->d_name,
 142                d.v->d_type != DT_SUBVOL
 143                ? le64_to_cpu(d.v->d_inum)
 144                : le32_to_cpu(d.v->d_child_subvol),
 145                bch2_d_type_str(d.v->d_type));
 146 }
 147
 148 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 149                                 subvol_inum dir, u8 type,
 150                                 const struct qstr *name, u64 dst)
 151 {
 152         struct bkey_i_dirent *dirent;
 153         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 154
 155         if (name->len > BCH_NAME_MAX)
 156                 return ERR_PTR(-ENAMETOOLONG);
 157
 158         BUG_ON(u64s > U8_MAX);
 159
 160         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 161         if (IS_ERR(dirent))
 162                 return dirent;
 163
 164         bkey_dirent_init(&dirent->k_i);
 165         dirent->k.u64s = u64s;
 166
 167         if (type != DT_SUBVOL) {
 168                 dirent->v.d_inum = cpu_to_le64(dst);
 169         } else {
 170                 dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
 171                 dirent->v.d_child_subvol = cpu_to_le32(dst);
 172         }
 173
 174         dirent->v.d_type = type;
 175
 176         memcpy(dirent->v.d_name, name->name, name->len);
 177         memset(dirent->v.d_name + name->len, 0,
 178                bkey_val_bytes(&dirent->k) -
 179                offsetof(struct bch_dirent, d_name) -
 180                name->len);
 181
 182         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 183
 184         return dirent;
 185 }
 186
 187 int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
 188                        const struct bch_hash_info *hash_info,
 189                        u8 type, const struct qstr *name, u64 dst_inum,
 190                        u64 *dir_offset, int flags)
 191 {
 192         struct bkey_i_dirent *dirent;
 193         int ret;
 194
 195         dirent = dirent_create_key(trans, dir, type, name, dst_inum);
 196         ret = PTR_ERR_OR_ZERO(dirent);
 197         if (ret)
 198                 return ret;
 199
 200         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 201                             dir, &dirent->k_i, flags);
 202         *dir_offset = dirent->k.p.offset;
 203
 204         return ret;
 205 }
 206
 207 static void dirent_copy_target(struct bkey_i_dirent *dst,
 208                                struct bkey_s_c_dirent src)
 209 {
 210         dst->v.d_inum = src.v->d_inum;
 211         dst->v.d_type = src.v->d_type;
 212 }
 213
 214 int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
 215                             struct bkey_s_c_dirent d, subvol_inum *target)
 216 {
 217         struct bch_subvolume s;
 218         int ret = 0;
 219
 220         if (d.v->d_type == DT_SUBVOL &&
 221             d.v->d_parent_subvol != dir.subvol)
 222                 return 1;
 223
 224         if (likely(d.v->d_type != DT_SUBVOL)) {
 225                 target->subvol  = dir.subvol;
 226                 target->inum    = le64_to_cpu(d.v->d_inum);
 227         } else {
 228                 target->subvol  = le32_to_cpu(d.v->d_child_subvol);
 229
 230                 ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_CACHED, &s);
 231
 232                 target->inum    = le64_to_cpu(s.inode);
 233         }
 234
 235         return ret;
 236 }
 237
 238 int bch2_dirent_rename(struct btree_trans *trans,
 239                 subvol_inum src_dir, struct bch_hash_info *src_hash,
 240                 subvol_inum dst_dir, struct bch_hash_info *dst_hash,
 241                 const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
 242                 const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
 243                 enum bch_rename_mode mode)
 244 {
 245         struct btree_iter src_iter = { NULL };
 246         struct btree_iter dst_iter = { NULL };
 247         struct bkey_s_c old_src, old_dst = bkey_s_c_null;
 248         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 249         struct bpos dst_pos =
 250                 POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
 251         unsigned src_type = 0, dst_type = 0, src_update_flags = 0;
 252         int ret = 0;
 253
 254         if (src_dir.subvol != dst_dir.subvol)
 255                 return -EXDEV;
 256
 257         memset(src_inum, 0, sizeof(*src_inum));
 258         memset(dst_inum, 0, sizeof(*dst_inum));
 259
 260         /* Lookup src: */
 261         ret = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
 262                                src_hash, src_dir, src_name,
 263                                BTREE_ITER_INTENT);
 264         if (ret)
 265                 goto out;
 266
 267         old_src = bch2_btree_iter_peek_slot(&src_iter);
 268         ret = bkey_err(old_src);
 269         if (ret)
 270                 goto out;
 271
 272         ret = bch2_dirent_read_target(trans, src_dir,
 273                         bkey_s_c_to_dirent(old_src), src_inum);
 274         if (ret)
 275                 goto out;
 276
 277         src_type = bkey_s_c_to_dirent(old_src).v->d_type;
 278
 279         if (src_type == DT_SUBVOL && mode == BCH_RENAME_EXCHANGE)
 280                 return -EOPNOTSUPP;
 281
 282
 283         /* Lookup dst: */
 284         if (mode == BCH_RENAME) {
 285                 /*
 286                  * Note that we're _not_ checking if the target already exists -
 287                  * we're relying on the VFS to do that check for us for
 288                  * correctness:
 289                  */
 290                 ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
 291                                      dst_hash, dst_dir, dst_name);
 292                 if (ret)
 293                         goto out;
 294         } else {
 295                 ret = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
 296                                        dst_hash, dst_dir, dst_name,
 297                                        BTREE_ITER_INTENT);
 298                 if (ret)
 299                         goto out;
 300
 301                 old_dst = bch2_btree_iter_peek_slot(&dst_iter);
 302                 ret = bkey_err(old_dst);
 303                 if (ret)
 304                         goto out;
 305
 306                 ret = bch2_dirent_read_target(trans, dst_dir,
 307                                 bkey_s_c_to_dirent(old_dst), dst_inum);
 308                 if (ret)
 309                         goto out;
 310
 311                 dst_type = bkey_s_c_to_dirent(old_dst).v->d_type;
 312
 313                 if (dst_type == DT_SUBVOL)
 314                         return -EOPNOTSUPP;
 315         }
 316
 317         if (mode != BCH_RENAME_EXCHANGE)
 318                 *src_offset = dst_iter.pos.offset;
 319
 320         /* Create new dst key: */
 321         new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
 322         ret = PTR_ERR_OR_ZERO(new_dst);
 323         if (ret)
 324                 goto out;
 325
 326         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 327         new_dst->k.p = dst_iter.pos;
 328
 329         /* Create new src key: */
 330         if (mode == BCH_RENAME_EXCHANGE) {
 331                 new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
 332                 ret = PTR_ERR_OR_ZERO(new_src);
 333                 if (ret)
 334                         goto out;
 335
 336                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 337                 new_src->k.p = src_iter.pos;
 338         } else {
 339                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 340                 ret = PTR_ERR_OR_ZERO(new_src);
 341                 if (ret)
 342                         goto out;
 343
 344                 bkey_init(&new_src->k);
 345                 new_src->k.p = src_iter.pos;
 346
 347                 if (bkey_le(dst_pos, src_iter.pos) &&
 348                     bkey_lt(src_iter.pos, dst_iter.pos)) {
 349                         /*
 350                          * We have a hash collision for the new dst key,
 351                          * and new_src - the key we're deleting - is between
 352                          * new_dst's hashed slot and the slot we're going to be
 353                          * inserting it into - oops.  This will break the hash
 354                          * table if we don't deal with it:
 355                          */
 356                         if (mode == BCH_RENAME) {
 357                                 /*
 358                                  * If we're not overwriting, we can just insert
 359                                  * new_dst at the src position:
 360                                  */
 361                                 new_src = new_dst;
 362                                 new_src->k.p = src_iter.pos;
 363                                 goto out_set_src;
 364                         } else {
 365                                 /* If we're overwriting, we can't insert new_dst
 366                                  * at a different slot because it has to
 367                                  * overwrite old_dst - just make sure to use a
 368                                  * whiteout when deleting src:
 369                                  */
 370                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 371                         }
 372                 } else {
 373                         /* Check if we need a whiteout to delete src: */
 374                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 375                                                        src_hash, &src_iter);
 376                         if (ret < 0)
 377                                 goto out;
 378
 379                         if (ret)
 380                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 381                 }
 382         }
 383
 384         ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
 385         if (ret)
 386                 goto out;
 387 out_set_src:
 388
 389         /*
 390          * If we're deleting a subvolume, we need to really delete the dirent,
 391          * not just emit a whiteout in the current snapshot:
 392          */
 393         if (src_type == DT_SUBVOL) {
 394                 bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
 395                 ret = bch2_btree_iter_traverse(&src_iter);
 396                 if (ret)
 397                         goto out;
 398
 399                 new_src->k.p = src_iter.pos;
 400                 src_update_flags |= BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE;
 401         }
 402
 403         ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
 404         if (ret)
 405                 goto out;
 406
 407         if (mode == BCH_RENAME_EXCHANGE)
 408                 *src_offset = new_src->k.p.offset;
 409         *dst_offset = new_dst->k.p.offset;
 410 out:
 411         bch2_trans_iter_exit(trans, &src_iter);
 412         bch2_trans_iter_exit(trans, &dst_iter);
 413         return ret;
 414 }
 415
 416 int __bch2_dirent_lookup_trans(struct btree_trans *trans,
 417                                struct btree_iter *iter,
 418                                subvol_inum dir,
 419                                const struct bch_hash_info *hash_info,
 420                                const struct qstr *name, subvol_inum *inum,
 421                                unsigned flags)
 422 {
 423         struct bkey_s_c k;
 424         struct bkey_s_c_dirent d;
 425         u32 snapshot;
 426         int ret;
 427
 428         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 429         if (ret)
 430                 return ret;
 431
 432         ret = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
 433                                hash_info, dir, name, flags);
 434         if (ret)
 435                 return ret;
 436
 437         k = bch2_btree_iter_peek_slot(iter);
 438         ret = bkey_err(k);
 439         if (ret)
 440                 goto err;
 441
 442         d = bkey_s_c_to_dirent(k);
 443
 444         ret = bch2_dirent_read_target(trans, dir, d, inum);
 445         if (ret > 0)
 446                 ret = -ENOENT;
 447 err:
 448         if (ret)
 449                 bch2_trans_iter_exit(trans, iter);
 450
 451         return ret;
 452 }
 453
 454 u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 455                        const struct bch_hash_info *hash_info,
 456                        const struct qstr *name, subvol_inum *inum)
 457 {
 458         struct btree_trans trans;
 459         struct btree_iter iter;
 460         int ret;
 461
 462         bch2_trans_init(&trans, c, 0, 0);
 463 retry:
 464         bch2_trans_begin(&trans);
 465
 466         ret = __bch2_dirent_lookup_trans(&trans, &iter, dir, hash_info,
 467                                           name, inum, 0);
 468         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 469                 goto retry;
 470         if (!ret)
 471                 bch2_trans_iter_exit(&trans, &iter);
 472         bch2_trans_exit(&trans);
 473         return ret;
 474 }
 475
 476 int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 477 {
 478         struct btree_iter iter;
 479         struct bkey_s_c k;
 480         u32 snapshot;
 481         int ret;
 482
 483         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 484         if (ret)
 485                 return ret;
 486
 487         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 488                            SPOS(dir.inum, 0, snapshot),
 489                            POS(dir.inum, U64_MAX), 0, k, ret)
 490                 if (k.k->type == KEY_TYPE_dirent) {
 491                         ret = -ENOTEMPTY;
 492                         break;
 493                 }
 494         bch2_trans_iter_exit(trans, &iter);
 495
 496         return ret;
 497 }
 498
 499 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 500 {
 501         struct btree_trans trans;
 502         struct btree_iter iter;
 503         struct bkey_s_c k;
 504         struct bkey_s_c_dirent dirent;
 505         subvol_inum target;
 506         u32 snapshot;
 507         int ret;
 508
 509         bch2_trans_init(&trans, c, 0, 0);
 510 retry:
 511         bch2_trans_begin(&trans);
 512
 513         ret = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
 514         if (ret)
 515                 goto err;
 516
 517         for_each_btree_key_upto_norestart(&trans, iter, BTREE_ID_dirents,
 518                            SPOS(inum.inum, ctx->pos, snapshot),
 519                            POS(inum.inum, U64_MAX), 0, k, ret) {
 520                 if (k.k->type != KEY_TYPE_dirent)
 521                         continue;
 522
 523                 dirent = bkey_s_c_to_dirent(k);
 524
 525                 ret = bch2_dirent_read_target(&trans, inum, dirent, &target);
 526                 if (ret < 0)
 527                         break;
 528                 if (ret)
 529                         continue;
 530
 531                 /*
 532                  * XXX: dir_emit() can fault and block, while we're holding
 533                  * locks
 534                  */
 535                 ctx->pos = dirent.k->p.offset;
 536                 if (!dir_emit(ctx, dirent.v->d_name,
 537                               bch2_dirent_name_bytes(dirent),
 538                               target.inum,
 539                               vfs_d_type(dirent.v->d_type)))
 540                         break;
 541                 ctx->pos = dirent.k->p.offset + 1;
 542
 543                 /*
 544                  * read_target looks up subvolumes, we can overflow paths if the
 545                  * directory has many subvolumes in it
 546                  */
 547                 ret = btree_trans_too_many_iters(&trans);
 548                 if (ret)
 549                         break;
 550         }
 551         bch2_trans_iter_exit(&trans, &iter);
 552 err:
 553         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 554                 goto retry;
 555
 556         bch2_trans_exit(&trans);
 557
 558         return ret;
 559 }