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_buf.h"
   5 #include "bkey_methods.h"
   6 #include "btree_update.h"
   7 #include "extents.h"
   8 #include "dirent.h"
   9 #include "fs.h"
  10 #include "keylist.h"
  11 #include "str_hash.h"
  12 #include "subvolume.h"
  13
  14 #include <linux/dcache.h>
  15
  16 static unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  17 {
  18         unsigned bkey_u64s = bkey_val_u64s(d.k);
  19         unsigned bkey_bytes = bkey_u64s * sizeof(u64);
  20         u64 last_u64 = ((u64*)d.v)[bkey_u64s - 1];
  21 #if CPU_BIG_ENDIAN
  22         unsigned trailing_nuls = last_u64 ? __builtin_ctzll(last_u64) / 8 : 64 / 8;
  23 #else
  24         unsigned trailing_nuls = last_u64 ? __builtin_clzll(last_u64) / 8 : 64 / 8;
  25 #endif
  26
  27         return bkey_bytes -
  28                 offsetof(struct bch_dirent, d_name) -
  29                 trailing_nuls;
  30 }
  31
  32 struct qstr bch2_dirent_get_name(struct bkey_s_c_dirent d)
  33 {
  34         return (struct qstr) QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  35 }
  36
  37 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  38                             const struct qstr *name)
  39 {
  40         struct bch_str_hash_ctx ctx;
  41
  42         bch2_str_hash_init(&ctx, info);
  43         bch2_str_hash_update(&ctx, info, name->name, name->len);
  44
  45         /* [0,2) reserved for dots */
  46         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  47 }
  48
  49 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  50 {
  51         return bch2_dirent_hash(info, key);
  52 }
  53
  54 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  55 {
  56         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  57         struct qstr name = bch2_dirent_get_name(d);
  58
  59         return bch2_dirent_hash(info, &name);
  60 }
  61
  62 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  63 {
  64         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  65         const struct qstr l_name = bch2_dirent_get_name(l);
  66         const struct qstr *r_name = _r;
  67
  68         return l_name.len - r_name->len ?: memcmp(l_name.name, r_name->name, l_name.len);
  69 }
  70
  71 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  72 {
  73         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  74         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  75         const struct qstr l_name = bch2_dirent_get_name(l);
  76         const struct qstr r_name = bch2_dirent_get_name(r);
  77
  78         return l_name.len - r_name.len ?: memcmp(l_name.name, r_name.name, l_name.len);
  79 }
  80
  81 static bool dirent_is_visible(subvol_inum inum, struct bkey_s_c k)
  82 {
  83         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  84
  85         if (d.v->d_type == DT_SUBVOL)
  86                 return le32_to_cpu(d.v->d_parent_subvol) == inum.subvol;
  87         return true;
  88 }
  89
  90 const struct bch_hash_desc bch2_dirent_hash_desc = {
  91         .btree_id       = BTREE_ID_dirents,
  92         .key_type       = KEY_TYPE_dirent,
  93         .hash_key       = dirent_hash_key,
  94         .hash_bkey      = dirent_hash_bkey,
  95         .cmp_key        = dirent_cmp_key,
  96         .cmp_bkey       = dirent_cmp_bkey,
  97         .is_visible     = dirent_is_visible,
  98 };
  99
 100 int bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k,
 101                         enum bkey_invalid_flags flags,
 102                         struct printbuf *err)
 103 {
 104         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 105         struct qstr d_name = bch2_dirent_get_name(d);
 106
 107         if (!d_name.len) {
 108                 prt_printf(err, "empty name");
 109                 return -BCH_ERR_invalid_bkey;
 110         }
 111
 112         if (bkey_val_u64s(k.k) > dirent_val_u64s(d_name.len)) {
 113                 prt_printf(err, "value too big (%zu > %u)",
 114                        bkey_val_u64s(k.k), dirent_val_u64s(d_name.len));
 115                 return -BCH_ERR_invalid_bkey;
 116         }
 117
 118         /*
 119          * Check new keys don't exceed the max length
 120          * (older keys may be larger.)
 121          */
 122         if ((flags & BKEY_INVALID_COMMIT) && d_name.len > BCH_NAME_MAX) {
 123                 prt_printf(err, "dirent name too big (%u > %u)",
 124                        d_name.len, BCH_NAME_MAX);
 125                 return -BCH_ERR_invalid_bkey;
 126         }
 127
 128         if (d_name.len != strnlen(d_name.name, d_name.len)) {
 129                 prt_printf(err, "dirent has stray data after name's NUL");
 130                 return -BCH_ERR_invalid_bkey;
 131         }
 132
 133         if (d_name.len == 1 && !memcmp(d_name.name, ".", 1)) {
 134                 prt_printf(err, "invalid name");
 135                 return -BCH_ERR_invalid_bkey;
 136         }
 137
 138         if (d_name.len == 2 && !memcmp(d_name.name, "..", 2)) {
 139                 prt_printf(err, "invalid name");
 140                 return -BCH_ERR_invalid_bkey;
 141         }
 142
 143         if (memchr(d_name.name, '/', d_name.len)) {
 144                 prt_printf(err, "invalid name");
 145                 return -BCH_ERR_invalid_bkey;
 146         }
 147
 148         if (d.v->d_type != DT_SUBVOL &&
 149             le64_to_cpu(d.v->d_inum) == d.k->p.inode) {
 150                 prt_printf(err, "dirent points to own directory");
 151                 return -BCH_ERR_invalid_bkey;
 152         }
 153
 154         return 0;
 155 }
 156
 157 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 158                          struct bkey_s_c k)
 159 {
 160         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 161         struct qstr d_name = bch2_dirent_get_name(d);
 162
 163         prt_printf(out, "%.*s -> %llu type %s",
 164                d_name.len,
 165                d_name.name,
 166                d.v->d_type != DT_SUBVOL
 167                ? le64_to_cpu(d.v->d_inum)
 168                : le32_to_cpu(d.v->d_child_subvol),
 169                bch2_d_type_str(d.v->d_type));
 170 }
 171
 172 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 173                                 subvol_inum dir, u8 type,
 174                                 const struct qstr *name, u64 dst)
 175 {
 176         struct bkey_i_dirent *dirent;
 177         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 178
 179         if (name->len > BCH_NAME_MAX)
 180                 return ERR_PTR(-ENAMETOOLONG);
 181
 182         BUG_ON(u64s > U8_MAX);
 183
 184         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 185         if (IS_ERR(dirent))
 186                 return dirent;
 187
 188         bkey_dirent_init(&dirent->k_i);
 189         dirent->k.u64s = u64s;
 190
 191         if (type != DT_SUBVOL) {
 192                 dirent->v.d_inum = cpu_to_le64(dst);
 193         } else {
 194                 dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
 195                 dirent->v.d_child_subvol = cpu_to_le32(dst);
 196         }
 197
 198         dirent->v.d_type = type;
 199
 200         memcpy(dirent->v.d_name, name->name, name->len);
 201         memset(dirent->v.d_name + name->len, 0,
 202                bkey_val_bytes(&dirent->k) -
 203                offsetof(struct bch_dirent, d_name) -
 204                name->len);
 205
 206         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 207
 208         return dirent;
 209 }
 210
 211 int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
 212                        const struct bch_hash_info *hash_info,
 213                        u8 type, const struct qstr *name, u64 dst_inum,
 214                        u64 *dir_offset, int flags)
 215 {
 216         struct bkey_i_dirent *dirent;
 217         int ret;
 218
 219         dirent = dirent_create_key(trans, dir, type, name, dst_inum);
 220         ret = PTR_ERR_OR_ZERO(dirent);
 221         if (ret)
 222                 return ret;
 223
 224         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 225                             dir, &dirent->k_i, flags);
 226         *dir_offset = dirent->k.p.offset;
 227
 228         return ret;
 229 }
 230
 231 static void dirent_copy_target(struct bkey_i_dirent *dst,
 232                                struct bkey_s_c_dirent src)
 233 {
 234         dst->v.d_inum = src.v->d_inum;
 235         dst->v.d_type = src.v->d_type;
 236 }
 237
 238 int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
 239                             struct bkey_s_c_dirent d, subvol_inum *target)
 240 {
 241         struct bch_subvolume s;
 242         int ret = 0;
 243
 244         if (d.v->d_type == DT_SUBVOL &&
 245             le32_to_cpu(d.v->d_parent_subvol) != dir.subvol)
 246                 return 1;
 247
 248         if (likely(d.v->d_type != DT_SUBVOL)) {
 249                 target->subvol  = dir.subvol;
 250                 target->inum    = le64_to_cpu(d.v->d_inum);
 251         } else {
 252                 target->subvol  = le32_to_cpu(d.v->d_child_subvol);
 253
 254                 ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_CACHED, &s);
 255
 256                 target->inum    = le64_to_cpu(s.inode);
 257         }
 258
 259         return ret;
 260 }
 261
 262 int bch2_dirent_rename(struct btree_trans *trans,
 263                 subvol_inum src_dir, struct bch_hash_info *src_hash,
 264                 subvol_inum dst_dir, struct bch_hash_info *dst_hash,
 265                 const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
 266                 const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
 267                 enum bch_rename_mode mode)
 268 {
 269         struct btree_iter src_iter = { NULL };
 270         struct btree_iter dst_iter = { NULL };
 271         struct bkey_s_c old_src, old_dst = bkey_s_c_null;
 272         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 273         struct bpos dst_pos =
 274                 POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
 275         unsigned src_type = 0, dst_type = 0, src_update_flags = 0;
 276         int ret = 0;
 277
 278         if (src_dir.subvol != dst_dir.subvol)
 279                 return -EXDEV;
 280
 281         memset(src_inum, 0, sizeof(*src_inum));
 282         memset(dst_inum, 0, sizeof(*dst_inum));
 283
 284         /* Lookup src: */
 285         ret = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
 286                                src_hash, src_dir, src_name,
 287                                BTREE_ITER_INTENT);
 288         if (ret)
 289                 goto out;
 290
 291         old_src = bch2_btree_iter_peek_slot(&src_iter);
 292         ret = bkey_err(old_src);
 293         if (ret)
 294                 goto out;
 295
 296         ret = bch2_dirent_read_target(trans, src_dir,
 297                         bkey_s_c_to_dirent(old_src), src_inum);
 298         if (ret)
 299                 goto out;
 300
 301         src_type = bkey_s_c_to_dirent(old_src).v->d_type;
 302
 303         if (src_type == DT_SUBVOL && mode == BCH_RENAME_EXCHANGE)
 304                 return -EOPNOTSUPP;
 305
 306
 307         /* Lookup dst: */
 308         if (mode == BCH_RENAME) {
 309                 /*
 310                  * Note that we're _not_ checking if the target already exists -
 311                  * we're relying on the VFS to do that check for us for
 312                  * correctness:
 313                  */
 314                 ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
 315                                      dst_hash, dst_dir, dst_name);
 316                 if (ret)
 317                         goto out;
 318         } else {
 319                 ret = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
 320                                        dst_hash, dst_dir, dst_name,
 321                                        BTREE_ITER_INTENT);
 322                 if (ret)
 323                         goto out;
 324
 325                 old_dst = bch2_btree_iter_peek_slot(&dst_iter);
 326                 ret = bkey_err(old_dst);
 327                 if (ret)
 328                         goto out;
 329
 330                 ret = bch2_dirent_read_target(trans, dst_dir,
 331                                 bkey_s_c_to_dirent(old_dst), dst_inum);
 332                 if (ret)
 333                         goto out;
 334
 335                 dst_type = bkey_s_c_to_dirent(old_dst).v->d_type;
 336
 337                 if (dst_type == DT_SUBVOL)
 338                         return -EOPNOTSUPP;
 339         }
 340
 341         if (mode != BCH_RENAME_EXCHANGE)
 342                 *src_offset = dst_iter.pos.offset;
 343
 344         /* Create new dst key: */
 345         new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
 346         ret = PTR_ERR_OR_ZERO(new_dst);
 347         if (ret)
 348                 goto out;
 349
 350         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 351         new_dst->k.p = dst_iter.pos;
 352
 353         /* Create new src key: */
 354         if (mode == BCH_RENAME_EXCHANGE) {
 355                 new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
 356                 ret = PTR_ERR_OR_ZERO(new_src);
 357                 if (ret)
 358                         goto out;
 359
 360                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 361                 new_src->k.p = src_iter.pos;
 362         } else {
 363                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 364                 ret = PTR_ERR_OR_ZERO(new_src);
 365                 if (ret)
 366                         goto out;
 367
 368                 bkey_init(&new_src->k);
 369                 new_src->k.p = src_iter.pos;
 370
 371                 if (bkey_le(dst_pos, src_iter.pos) &&
 372                     bkey_lt(src_iter.pos, dst_iter.pos)) {
 373                         /*
 374                          * We have a hash collision for the new dst key,
 375                          * and new_src - the key we're deleting - is between
 376                          * new_dst's hashed slot and the slot we're going to be
 377                          * inserting it into - oops.  This will break the hash
 378                          * table if we don't deal with it:
 379                          */
 380                         if (mode == BCH_RENAME) {
 381                                 /*
 382                                  * If we're not overwriting, we can just insert
 383                                  * new_dst at the src position:
 384                                  */
 385                                 new_src = new_dst;
 386                                 new_src->k.p = src_iter.pos;
 387                                 goto out_set_src;
 388                         } else {
 389                                 /* If we're overwriting, we can't insert new_dst
 390                                  * at a different slot because it has to
 391                                  * overwrite old_dst - just make sure to use a
 392                                  * whiteout when deleting src:
 393                                  */
 394                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 395                         }
 396                 } else {
 397                         /* Check if we need a whiteout to delete src: */
 398                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 399                                                        src_hash, &src_iter);
 400                         if (ret < 0)
 401                                 goto out;
 402
 403                         if (ret)
 404                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 405                 }
 406         }
 407
 408         ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
 409         if (ret)
 410                 goto out;
 411 out_set_src:
 412
 413         /*
 414          * If we're deleting a subvolume, we need to really delete the dirent,
 415          * not just emit a whiteout in the current snapshot:
 416          */
 417         if (src_type == DT_SUBVOL) {
 418                 bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
 419                 ret = bch2_btree_iter_traverse(&src_iter);
 420                 if (ret)
 421                         goto out;
 422
 423                 new_src->k.p = src_iter.pos;
 424                 src_update_flags |= BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE;
 425         }
 426
 427         ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
 428         if (ret)
 429                 goto out;
 430
 431         if (mode == BCH_RENAME_EXCHANGE)
 432                 *src_offset = new_src->k.p.offset;
 433         *dst_offset = new_dst->k.p.offset;
 434 out:
 435         bch2_trans_iter_exit(trans, &src_iter);
 436         bch2_trans_iter_exit(trans, &dst_iter);
 437         return ret;
 438 }
 439
 440 int __bch2_dirent_lookup_trans(struct btree_trans *trans,
 441                                struct btree_iter *iter,
 442                                subvol_inum dir,
 443                                const struct bch_hash_info *hash_info,
 444                                const struct qstr *name, subvol_inum *inum,
 445                                unsigned flags)
 446 {
 447         struct bkey_s_c k;
 448         struct bkey_s_c_dirent d;
 449         u32 snapshot;
 450         int ret;
 451
 452         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 453         if (ret)
 454                 return ret;
 455
 456         ret = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
 457                                hash_info, dir, name, flags);
 458         if (ret)
 459                 return ret;
 460
 461         k = bch2_btree_iter_peek_slot(iter);
 462         ret = bkey_err(k);
 463         if (ret)
 464                 goto err;
 465
 466         d = bkey_s_c_to_dirent(k);
 467
 468         ret = bch2_dirent_read_target(trans, dir, d, inum);
 469         if (ret > 0)
 470                 ret = -ENOENT;
 471 err:
 472         if (ret)
 473                 bch2_trans_iter_exit(trans, iter);
 474
 475         return ret;
 476 }
 477
 478 u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 479                        const struct bch_hash_info *hash_info,
 480                        const struct qstr *name, subvol_inum *inum)
 481 {
 482         struct btree_trans *trans = bch2_trans_get(c);
 483         struct btree_iter iter;
 484         int ret;
 485 retry:
 486         bch2_trans_begin(trans);
 487
 488         ret = __bch2_dirent_lookup_trans(trans, &iter, dir, hash_info,
 489                                           name, inum, 0);
 490         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 491                 goto retry;
 492         if (!ret)
 493                 bch2_trans_iter_exit(trans, &iter);
 494         bch2_trans_put(trans);
 495         return ret;
 496 }
 497
 498 int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 499 {
 500         struct btree_iter iter;
 501         struct bkey_s_c k;
 502         u32 snapshot;
 503         int ret;
 504
 505         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 506         if (ret)
 507                 return ret;
 508
 509         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 510                            SPOS(dir.inum, 0, snapshot),
 511                            POS(dir.inum, U64_MAX), 0, k, ret)
 512                 if (k.k->type == KEY_TYPE_dirent) {
 513                         ret = -ENOTEMPTY;
 514                         break;
 515                 }
 516         bch2_trans_iter_exit(trans, &iter);
 517
 518         return ret;
 519 }
 520
 521 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 522 {
 523         struct btree_trans *trans = bch2_trans_get(c);
 524         struct btree_iter iter;
 525         struct bkey_s_c k;
 526         struct bkey_s_c_dirent dirent;
 527         subvol_inum target;
 528         u32 snapshot;
 529         struct bkey_buf sk;
 530         struct qstr name;
 531         int ret;
 532
 533         bch2_bkey_buf_init(&sk);
 534 retry:
 535         bch2_trans_begin(trans);
 536
 537         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 538         if (ret)
 539                 goto err;
 540
 541         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 542                            SPOS(inum.inum, ctx->pos, snapshot),
 543                            POS(inum.inum, U64_MAX), 0, k, ret) {
 544                 if (k.k->type != KEY_TYPE_dirent)
 545                         continue;
 546
 547                 dirent = bkey_s_c_to_dirent(k);
 548
 549                 ret = bch2_dirent_read_target(trans, inum, dirent, &target);
 550                 if (ret < 0)
 551                         break;
 552                 if (ret)
 553                         continue;
 554
 555                 /* dir_emit() can fault and block: */
 556                 bch2_bkey_buf_reassemble(&sk, c, k);
 557                 dirent = bkey_i_to_s_c_dirent(sk.k);
 558                 bch2_trans_unlock(trans);
 559
 560                 name = bch2_dirent_get_name(dirent);
 561
 562                 ctx->pos = dirent.k->p.offset;
 563                 if (!dir_emit(ctx, name.name,
 564                               name.len,
 565                               target.inum,
 566                               vfs_d_type(dirent.v->d_type)))
 567                         break;
 568                 ctx->pos = dirent.k->p.offset + 1;
 569
 570                 /*
 571                  * read_target looks up subvolumes, we can overflow paths if the
 572                  * directory has many subvolumes in it
 573                  */
 574                 ret = btree_trans_too_many_iters(trans);
 575                 if (ret)
 576                         break;
 577         }
 578         bch2_trans_iter_exit(trans, &iter);
 579 err:
 580         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 581                 goto retry;
 582
 583         bch2_trans_put(trans);
 584         bch2_bkey_buf_exit(&sk, c);
 585
 586         return ret;
 587 }