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 unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  17 {
  18         unsigned len = bkey_val_bytes(d.k) -
  19                 offsetof(struct bch_dirent, d_name);
  20
  21         return strnlen(d.v->d_name, len);
  22 }
  23
  24 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  25                             const struct qstr *name)
  26 {
  27         struct bch_str_hash_ctx ctx;
  28
  29         bch2_str_hash_init(&ctx, info);
  30         bch2_str_hash_update(&ctx, info, name->name, name->len);
  31
  32         /* [0,2) reserved for dots */
  33         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  34 }
  35
  36 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  37 {
  38         return bch2_dirent_hash(info, key);
  39 }
  40
  41 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  42 {
  43         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  44         struct qstr name = QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  45
  46         return bch2_dirent_hash(info, &name);
  47 }
  48
  49 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  50 {
  51         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  52         int len = bch2_dirent_name_bytes(l);
  53         const struct qstr *r = _r;
  54
  55         return len - r->len ?: memcmp(l.v->d_name, r->name, len);
  56 }
  57
  58 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  59 {
  60         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  61         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  62         int l_len = bch2_dirent_name_bytes(l);
  63         int r_len = bch2_dirent_name_bytes(r);
  64
  65         return l_len - r_len ?: memcmp(l.v->d_name, r.v->d_name, l_len);
  66 }
  67
  68 static bool dirent_is_visible(subvol_inum inum, struct bkey_s_c k)
  69 {
  70         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  71
  72         if (d.v->d_type == DT_SUBVOL)
  73                 return le32_to_cpu(d.v->d_parent_subvol) == inum.subvol;
  74         return true;
  75 }
  76
  77 const struct bch_hash_desc bch2_dirent_hash_desc = {
  78         .btree_id       = BTREE_ID_dirents,
  79         .key_type       = KEY_TYPE_dirent,
  80         .hash_key       = dirent_hash_key,
  81         .hash_bkey      = dirent_hash_bkey,
  82         .cmp_key        = dirent_cmp_key,
  83         .cmp_bkey       = dirent_cmp_bkey,
  84         .is_visible     = dirent_is_visible,
  85 };
  86
  87 int bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k,
  88                         enum bkey_invalid_flags flags,
  89                         struct printbuf *err)
  90 {
  91         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  92         unsigned len;
  93
  94         len = bch2_dirent_name_bytes(d);
  95         if (!len) {
  96                 prt_printf(err, "empty name");
  97                 return -BCH_ERR_invalid_bkey;
  98         }
  99
 100         if (bkey_val_u64s(k.k) > dirent_val_u64s(len)) {
 101                 prt_printf(err, "value too big (%zu > %u)",
 102                        bkey_val_u64s(k.k), dirent_val_u64s(len));
 103                 return -BCH_ERR_invalid_bkey;
 104         }
 105
 106         if (len > BCH_NAME_MAX) {
 107                 prt_printf(err, "dirent name too big (%u > %u)",
 108                        len, BCH_NAME_MAX);
 109                 return -BCH_ERR_invalid_bkey;
 110         }
 111
 112         if (len == 1 && !memcmp(d.v->d_name, ".", 1)) {
 113                 prt_printf(err, "invalid name");
 114                 return -BCH_ERR_invalid_bkey;
 115         }
 116
 117         if (len == 2 && !memcmp(d.v->d_name, "..", 2)) {
 118                 prt_printf(err, "invalid name");
 119                 return -BCH_ERR_invalid_bkey;
 120         }
 121
 122         if (memchr(d.v->d_name, '/', len)) {
 123                 prt_printf(err, "invalid name");
 124                 return -BCH_ERR_invalid_bkey;
 125         }
 126
 127         if (d.v->d_type != DT_SUBVOL &&
 128             le64_to_cpu(d.v->d_inum) == d.k->p.inode) {
 129                 prt_printf(err, "dirent points to own directory");
 130                 return -BCH_ERR_invalid_bkey;
 131         }
 132
 133         return 0;
 134 }
 135
 136 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 137                          struct bkey_s_c k)
 138 {
 139         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 140
 141         prt_printf(out, "%.*s -> %llu type %s",
 142                bch2_dirent_name_bytes(d),
 143                d.v->d_name,
 144                d.v->d_type != DT_SUBVOL
 145                ? le64_to_cpu(d.v->d_inum)
 146                : le32_to_cpu(d.v->d_child_subvol),
 147                bch2_d_type_str(d.v->d_type));
 148 }
 149
 150 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 151                                 subvol_inum dir, u8 type,
 152                                 const struct qstr *name, u64 dst)
 153 {
 154         struct bkey_i_dirent *dirent;
 155         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 156
 157         if (name->len > BCH_NAME_MAX)
 158                 return ERR_PTR(-ENAMETOOLONG);
 159
 160         BUG_ON(u64s > U8_MAX);
 161
 162         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 163         if (IS_ERR(dirent))
 164                 return dirent;
 165
 166         bkey_dirent_init(&dirent->k_i);
 167         dirent->k.u64s = u64s;
 168
 169         if (type != DT_SUBVOL) {
 170                 dirent->v.d_inum = cpu_to_le64(dst);
 171         } else {
 172                 dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
 173                 dirent->v.d_child_subvol = cpu_to_le32(dst);
 174         }
 175
 176         dirent->v.d_type = type;
 177
 178         memcpy(dirent->v.d_name, name->name, name->len);
 179         memset(dirent->v.d_name + name->len, 0,
 180                bkey_val_bytes(&dirent->k) -
 181                offsetof(struct bch_dirent, d_name) -
 182                name->len);
 183
 184         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 185
 186         return dirent;
 187 }
 188
 189 int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
 190                        const struct bch_hash_info *hash_info,
 191                        u8 type, const struct qstr *name, u64 dst_inum,
 192                        u64 *dir_offset, int flags)
 193 {
 194         struct bkey_i_dirent *dirent;
 195         int ret;
 196
 197         dirent = dirent_create_key(trans, dir, type, name, dst_inum);
 198         ret = PTR_ERR_OR_ZERO(dirent);
 199         if (ret)
 200                 return ret;
 201
 202         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 203                             dir, &dirent->k_i, flags);
 204         *dir_offset = dirent->k.p.offset;
 205
 206         return ret;
 207 }
 208
 209 static void dirent_copy_target(struct bkey_i_dirent *dst,
 210                                struct bkey_s_c_dirent src)
 211 {
 212         dst->v.d_inum = src.v->d_inum;
 213         dst->v.d_type = src.v->d_type;
 214 }
 215
 216 int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
 217                             struct bkey_s_c_dirent d, subvol_inum *target)
 218 {
 219         struct bch_subvolume s;
 220         int ret = 0;
 221
 222         if (d.v->d_type == DT_SUBVOL &&
 223             le32_to_cpu(d.v->d_parent_subvol) != dir.subvol)
 224                 return 1;
 225
 226         if (likely(d.v->d_type != DT_SUBVOL)) {
 227                 target->subvol  = dir.subvol;
 228                 target->inum    = le64_to_cpu(d.v->d_inum);
 229         } else {
 230                 target->subvol  = le32_to_cpu(d.v->d_child_subvol);
 231
 232                 ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_CACHED, &s);
 233
 234                 target->inum    = le64_to_cpu(s.inode);
 235         }
 236
 237         return ret;
 238 }
 239
 240 int bch2_dirent_rename(struct btree_trans *trans,
 241                 subvol_inum src_dir, struct bch_hash_info *src_hash,
 242                 subvol_inum dst_dir, struct bch_hash_info *dst_hash,
 243                 const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
 244                 const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
 245                 enum bch_rename_mode mode)
 246 {
 247         struct btree_iter src_iter = { NULL };
 248         struct btree_iter dst_iter = { NULL };
 249         struct bkey_s_c old_src, old_dst = bkey_s_c_null;
 250         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 251         struct bpos dst_pos =
 252                 POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
 253         unsigned src_type = 0, dst_type = 0, src_update_flags = 0;
 254         int ret = 0;
 255
 256         if (src_dir.subvol != dst_dir.subvol)
 257                 return -EXDEV;
 258
 259         memset(src_inum, 0, sizeof(*src_inum));
 260         memset(dst_inum, 0, sizeof(*dst_inum));
 261
 262         /* Lookup src: */
 263         ret = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
 264                                src_hash, src_dir, src_name,
 265                                BTREE_ITER_INTENT);
 266         if (ret)
 267                 goto out;
 268
 269         old_src = bch2_btree_iter_peek_slot(&src_iter);
 270         ret = bkey_err(old_src);
 271         if (ret)
 272                 goto out;
 273
 274         ret = bch2_dirent_read_target(trans, src_dir,
 275                         bkey_s_c_to_dirent(old_src), src_inum);
 276         if (ret)
 277                 goto out;
 278
 279         src_type = bkey_s_c_to_dirent(old_src).v->d_type;
 280
 281         if (src_type == DT_SUBVOL && mode == BCH_RENAME_EXCHANGE)
 282                 return -EOPNOTSUPP;
 283
 284
 285         /* Lookup dst: */
 286         if (mode == BCH_RENAME) {
 287                 /*
 288                  * Note that we're _not_ checking if the target already exists -
 289                  * we're relying on the VFS to do that check for us for
 290                  * correctness:
 291                  */
 292                 ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
 293                                      dst_hash, dst_dir, dst_name);
 294                 if (ret)
 295                         goto out;
 296         } else {
 297                 ret = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
 298                                        dst_hash, dst_dir, dst_name,
 299                                        BTREE_ITER_INTENT);
 300                 if (ret)
 301                         goto out;
 302
 303                 old_dst = bch2_btree_iter_peek_slot(&dst_iter);
 304                 ret = bkey_err(old_dst);
 305                 if (ret)
 306                         goto out;
 307
 308                 ret = bch2_dirent_read_target(trans, dst_dir,
 309                                 bkey_s_c_to_dirent(old_dst), dst_inum);
 310                 if (ret)
 311                         goto out;
 312
 313                 dst_type = bkey_s_c_to_dirent(old_dst).v->d_type;
 314
 315                 if (dst_type == DT_SUBVOL)
 316                         return -EOPNOTSUPP;
 317         }
 318
 319         if (mode != BCH_RENAME_EXCHANGE)
 320                 *src_offset = dst_iter.pos.offset;
 321
 322         /* Create new dst key: */
 323         new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
 324         ret = PTR_ERR_OR_ZERO(new_dst);
 325         if (ret)
 326                 goto out;
 327
 328         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 329         new_dst->k.p = dst_iter.pos;
 330
 331         /* Create new src key: */
 332         if (mode == BCH_RENAME_EXCHANGE) {
 333                 new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
 334                 ret = PTR_ERR_OR_ZERO(new_src);
 335                 if (ret)
 336                         goto out;
 337
 338                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 339                 new_src->k.p = src_iter.pos;
 340         } else {
 341                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 342                 ret = PTR_ERR_OR_ZERO(new_src);
 343                 if (ret)
 344                         goto out;
 345
 346                 bkey_init(&new_src->k);
 347                 new_src->k.p = src_iter.pos;
 348
 349                 if (bkey_le(dst_pos, src_iter.pos) &&
 350                     bkey_lt(src_iter.pos, dst_iter.pos)) {
 351                         /*
 352                          * We have a hash collision for the new dst key,
 353                          * and new_src - the key we're deleting - is between
 354                          * new_dst's hashed slot and the slot we're going to be
 355                          * inserting it into - oops.  This will break the hash
 356                          * table if we don't deal with it:
 357                          */
 358                         if (mode == BCH_RENAME) {
 359                                 /*
 360                                  * If we're not overwriting, we can just insert
 361                                  * new_dst at the src position:
 362                                  */
 363                                 new_src = new_dst;
 364                                 new_src->k.p = src_iter.pos;
 365                                 goto out_set_src;
 366                         } else {
 367                                 /* If we're overwriting, we can't insert new_dst
 368                                  * at a different slot because it has to
 369                                  * overwrite old_dst - just make sure to use a
 370                                  * whiteout when deleting src:
 371                                  */
 372                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 373                         }
 374                 } else {
 375                         /* Check if we need a whiteout to delete src: */
 376                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 377                                                        src_hash, &src_iter);
 378                         if (ret < 0)
 379                                 goto out;
 380
 381                         if (ret)
 382                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 383                 }
 384         }
 385
 386         ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
 387         if (ret)
 388                 goto out;
 389 out_set_src:
 390
 391         /*
 392          * If we're deleting a subvolume, we need to really delete the dirent,
 393          * not just emit a whiteout in the current snapshot:
 394          */
 395         if (src_type == DT_SUBVOL) {
 396                 bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
 397                 ret = bch2_btree_iter_traverse(&src_iter);
 398                 if (ret)
 399                         goto out;
 400
 401                 new_src->k.p = src_iter.pos;
 402                 src_update_flags |= BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE;
 403         }
 404
 405         ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
 406         if (ret)
 407                 goto out;
 408
 409         if (mode == BCH_RENAME_EXCHANGE)
 410                 *src_offset = new_src->k.p.offset;
 411         *dst_offset = new_dst->k.p.offset;
 412 out:
 413         bch2_trans_iter_exit(trans, &src_iter);
 414         bch2_trans_iter_exit(trans, &dst_iter);
 415         return ret;
 416 }
 417
 418 int __bch2_dirent_lookup_trans(struct btree_trans *trans,
 419                                struct btree_iter *iter,
 420                                subvol_inum dir,
 421                                const struct bch_hash_info *hash_info,
 422                                const struct qstr *name, subvol_inum *inum,
 423                                unsigned flags)
 424 {
 425         struct bkey_s_c k;
 426         struct bkey_s_c_dirent d;
 427         u32 snapshot;
 428         int ret;
 429
 430         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 431         if (ret)
 432                 return ret;
 433
 434         ret = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
 435                                hash_info, dir, name, flags);
 436         if (ret)
 437                 return ret;
 438
 439         k = bch2_btree_iter_peek_slot(iter);
 440         ret = bkey_err(k);
 441         if (ret)
 442                 goto err;
 443
 444         d = bkey_s_c_to_dirent(k);
 445
 446         ret = bch2_dirent_read_target(trans, dir, d, inum);
 447         if (ret > 0)
 448                 ret = -ENOENT;
 449 err:
 450         if (ret)
 451                 bch2_trans_iter_exit(trans, iter);
 452
 453         return ret;
 454 }
 455
 456 u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 457                        const struct bch_hash_info *hash_info,
 458                        const struct qstr *name, subvol_inum *inum)
 459 {
 460         struct btree_trans trans;
 461         struct btree_iter iter;
 462         int ret;
 463
 464         bch2_trans_init(&trans, c, 0, 0);
 465 retry:
 466         bch2_trans_begin(&trans);
 467
 468         ret = __bch2_dirent_lookup_trans(&trans, &iter, dir, hash_info,
 469                                           name, inum, 0);
 470         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 471                 goto retry;
 472         if (!ret)
 473                 bch2_trans_iter_exit(&trans, &iter);
 474         bch2_trans_exit(&trans);
 475         return ret;
 476 }
 477
 478 int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 479 {
 480         struct btree_iter iter;
 481         struct bkey_s_c k;
 482         u32 snapshot;
 483         int ret;
 484
 485         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 486         if (ret)
 487                 return ret;
 488
 489         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 490                            SPOS(dir.inum, 0, snapshot),
 491                            POS(dir.inum, U64_MAX), 0, k, ret)
 492                 if (k.k->type == KEY_TYPE_dirent) {
 493                         ret = -ENOTEMPTY;
 494                         break;
 495                 }
 496         bch2_trans_iter_exit(trans, &iter);
 497
 498         return ret;
 499 }
 500
 501 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 502 {
 503         struct btree_trans trans;
 504         struct btree_iter iter;
 505         struct bkey_s_c k;
 506         struct bkey_s_c_dirent dirent;
 507         subvol_inum target;
 508         u32 snapshot;
 509         struct bkey_buf sk;
 510         int ret;
 511
 512         bch2_bkey_buf_init(&sk);
 513         bch2_trans_init(&trans, c, 0, 0);
 514 retry:
 515         bch2_trans_begin(&trans);
 516
 517         ret = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
 518         if (ret)
 519                 goto err;
 520
 521         for_each_btree_key_upto_norestart(&trans, iter, BTREE_ID_dirents,
 522                            SPOS(inum.inum, ctx->pos, snapshot),
 523                            POS(inum.inum, U64_MAX), 0, k, ret) {
 524                 if (k.k->type != KEY_TYPE_dirent)
 525                         continue;
 526
 527                 dirent = bkey_s_c_to_dirent(k);
 528
 529                 ret = bch2_dirent_read_target(&trans, inum, dirent, &target);
 530                 if (ret < 0)
 531                         break;
 532                 if (ret)
 533                         continue;
 534
 535                 /* dir_emit() can fault and block: */
 536                 bch2_bkey_buf_reassemble(&sk, c, k);
 537                 dirent = bkey_i_to_s_c_dirent(sk.k);
 538                 bch2_trans_unlock(&trans);
 539
 540                 ctx->pos = dirent.k->p.offset;
 541                 if (!dir_emit(ctx, dirent.v->d_name,
 542                               bch2_dirent_name_bytes(dirent),
 543                               target.inum,
 544                               vfs_d_type(dirent.v->d_type)))
 545                         break;
 546                 ctx->pos = dirent.k->p.offset + 1;
 547
 548                 /*
 549                  * read_target looks up subvolumes, we can overflow paths if the
 550                  * directory has many subvolumes in it
 551                  */
 552                 ret = btree_trans_too_many_iters(&trans);
 553                 if (ret)
 554                         break;
 555         }
 556         bch2_trans_iter_exit(&trans, &iter);
 557 err:
 558         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 559                 goto retry;
 560
 561         bch2_trans_exit(&trans);
 562         bch2_bkey_buf_exit(&sk, c);
 563
 564         return ret;
 565 }