git.sesse.net Git - bcachefs-tools-debian/blob - c_src/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 !qstr_eq(l_name, *r_name);
  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 !qstr_eq(l_name, r_name);
  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(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         int ret = 0;
 107
 108         bkey_fsck_err_on(!d_name.len, c, err,
 109                          dirent_empty_name,
 110                          "empty name");
 111
 112         bkey_fsck_err_on(bkey_val_u64s(k.k) > dirent_val_u64s(d_name.len), c, err,
 113                          dirent_val_too_big,
 114                          "value too big (%zu > %u)",
 115                          bkey_val_u64s(k.k), dirent_val_u64s(d_name.len));
 116
 117         /*
 118          * Check new keys don't exceed the max length
 119          * (older keys may be larger.)
 120          */
 121         bkey_fsck_err_on((flags & BKEY_INVALID_COMMIT) && d_name.len > BCH_NAME_MAX, c, err,
 122                          dirent_name_too_long,
 123                          "dirent name too big (%u > %u)",
 124                          d_name.len, BCH_NAME_MAX);
 125
 126         bkey_fsck_err_on(d_name.len != strnlen(d_name.name, d_name.len), c, err,
 127                          dirent_name_embedded_nul,
 128                          "dirent has stray data after name's NUL");
 129
 130         bkey_fsck_err_on((d_name.len == 1 && !memcmp(d_name.name, ".", 1)) ||
 131                          (d_name.len == 2 && !memcmp(d_name.name, "..", 2)), c, err,
 132                          dirent_name_dot_or_dotdot,
 133                          "invalid name");
 134
 135         bkey_fsck_err_on(memchr(d_name.name, '/', d_name.len), c, err,
 136                          dirent_name_has_slash,
 137                          "name with /");
 138
 139         bkey_fsck_err_on(d.v->d_type != DT_SUBVOL &&
 140                          le64_to_cpu(d.v->d_inum) == d.k->p.inode, c, err,
 141                          dirent_to_itself,
 142                          "dirent points to own directory");
 143 fsck_err:
 144         return ret;
 145 }
 146
 147 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 148                          struct bkey_s_c k)
 149 {
 150         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 151         struct qstr d_name = bch2_dirent_get_name(d);
 152
 153         prt_printf(out, "%.*s -> %llu type %s",
 154                d_name.len,
 155                d_name.name,
 156                d.v->d_type != DT_SUBVOL
 157                ? le64_to_cpu(d.v->d_inum)
 158                : le32_to_cpu(d.v->d_child_subvol),
 159                bch2_d_type_str(d.v->d_type));
 160 }
 161
 162 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 163                                 subvol_inum dir, u8 type,
 164                                 const struct qstr *name, u64 dst)
 165 {
 166         struct bkey_i_dirent *dirent;
 167         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 168
 169         if (name->len > BCH_NAME_MAX)
 170                 return ERR_PTR(-ENAMETOOLONG);
 171
 172         BUG_ON(u64s > U8_MAX);
 173
 174         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 175         if (IS_ERR(dirent))
 176                 return dirent;
 177
 178         bkey_dirent_init(&dirent->k_i);
 179         dirent->k.u64s = u64s;
 180
 181         if (type != DT_SUBVOL) {
 182                 dirent->v.d_inum = cpu_to_le64(dst);
 183         } else {
 184                 dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
 185                 dirent->v.d_child_subvol = cpu_to_le32(dst);
 186         }
 187
 188         dirent->v.d_type = type;
 189
 190         memcpy(dirent->v.d_name, name->name, name->len);
 191         memset(dirent->v.d_name + name->len, 0,
 192                bkey_val_bytes(&dirent->k) -
 193                offsetof(struct bch_dirent, d_name) -
 194                name->len);
 195
 196         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 197
 198         return dirent;
 199 }
 200
 201 int bch2_dirent_create_snapshot(struct btree_trans *trans,
 202                         u64 dir, u32 snapshot,
 203                         const struct bch_hash_info *hash_info,
 204                         u8 type, const struct qstr *name, u64 dst_inum,
 205                         u64 *dir_offset,
 206                         bch_str_hash_flags_t str_hash_flags)
 207 {
 208         subvol_inum zero_inum = { 0 };
 209         struct bkey_i_dirent *dirent;
 210         int ret;
 211
 212         dirent = dirent_create_key(trans, zero_inum, type, name, dst_inum);
 213         ret = PTR_ERR_OR_ZERO(dirent);
 214         if (ret)
 215                 return ret;
 216
 217         dirent->k.p.inode       = dir;
 218         dirent->k.p.snapshot    = snapshot;
 219
 220         ret = bch2_hash_set_snapshot(trans, bch2_dirent_hash_desc, hash_info,
 221                                      zero_inum, snapshot,
 222                                      &dirent->k_i, str_hash_flags,
 223                                      BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 224         *dir_offset = dirent->k.p.offset;
 225
 226         return ret;
 227 }
 228
 229 int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
 230                        const struct bch_hash_info *hash_info,
 231                        u8 type, const struct qstr *name, u64 dst_inum,
 232                        u64 *dir_offset,
 233                        bch_str_hash_flags_t str_hash_flags)
 234 {
 235         struct bkey_i_dirent *dirent;
 236         int ret;
 237
 238         dirent = dirent_create_key(trans, dir, type, name, dst_inum);
 239         ret = PTR_ERR_OR_ZERO(dirent);
 240         if (ret)
 241                 return ret;
 242
 243         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 244                             dir, &dirent->k_i, str_hash_flags);
 245         *dir_offset = dirent->k.p.offset;
 246
 247         return ret;
 248 }
 249
 250 static void dirent_copy_target(struct bkey_i_dirent *dst,
 251                                struct bkey_s_c_dirent src)
 252 {
 253         dst->v.d_inum = src.v->d_inum;
 254         dst->v.d_type = src.v->d_type;
 255 }
 256
 257 int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
 258                             struct bkey_s_c_dirent d, subvol_inum *target)
 259 {
 260         struct bch_subvolume s;
 261         int ret = 0;
 262
 263         if (d.v->d_type == DT_SUBVOL &&
 264             le32_to_cpu(d.v->d_parent_subvol) != dir.subvol)
 265                 return 1;
 266
 267         if (likely(d.v->d_type != DT_SUBVOL)) {
 268                 target->subvol  = dir.subvol;
 269                 target->inum    = le64_to_cpu(d.v->d_inum);
 270         } else {
 271                 target->subvol  = le32_to_cpu(d.v->d_child_subvol);
 272
 273                 ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_CACHED, &s);
 274
 275                 target->inum    = le64_to_cpu(s.inode);
 276         }
 277
 278         return ret;
 279 }
 280
 281 int bch2_dirent_rename(struct btree_trans *trans,
 282                 subvol_inum src_dir, struct bch_hash_info *src_hash,
 283                 subvol_inum dst_dir, struct bch_hash_info *dst_hash,
 284                 const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
 285                 const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
 286                 enum bch_rename_mode mode)
 287 {
 288         struct btree_iter src_iter = { NULL };
 289         struct btree_iter dst_iter = { NULL };
 290         struct bkey_s_c old_src, old_dst = bkey_s_c_null;
 291         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 292         struct bpos dst_pos =
 293                 POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
 294         unsigned src_type = 0, dst_type = 0, src_update_flags = 0;
 295         int ret = 0;
 296
 297         if (src_dir.subvol != dst_dir.subvol)
 298                 return -EXDEV;
 299
 300         memset(src_inum, 0, sizeof(*src_inum));
 301         memset(dst_inum, 0, sizeof(*dst_inum));
 302
 303         /* Lookup src: */
 304         ret = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
 305                                src_hash, src_dir, src_name,
 306                                BTREE_ITER_INTENT);
 307         if (ret)
 308                 goto out;
 309
 310         old_src = bch2_btree_iter_peek_slot(&src_iter);
 311         ret = bkey_err(old_src);
 312         if (ret)
 313                 goto out;
 314
 315         ret = bch2_dirent_read_target(trans, src_dir,
 316                         bkey_s_c_to_dirent(old_src), src_inum);
 317         if (ret)
 318                 goto out;
 319
 320         src_type = bkey_s_c_to_dirent(old_src).v->d_type;
 321
 322         if (src_type == DT_SUBVOL && mode == BCH_RENAME_EXCHANGE)
 323                 return -EOPNOTSUPP;
 324
 325
 326         /* Lookup dst: */
 327         if (mode == BCH_RENAME) {
 328                 /*
 329                  * Note that we're _not_ checking if the target already exists -
 330                  * we're relying on the VFS to do that check for us for
 331                  * correctness:
 332                  */
 333                 ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
 334                                      dst_hash, dst_dir, dst_name);
 335                 if (ret)
 336                         goto out;
 337         } else {
 338                 ret = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
 339                                        dst_hash, dst_dir, dst_name,
 340                                        BTREE_ITER_INTENT);
 341                 if (ret)
 342                         goto out;
 343
 344                 old_dst = bch2_btree_iter_peek_slot(&dst_iter);
 345                 ret = bkey_err(old_dst);
 346                 if (ret)
 347                         goto out;
 348
 349                 ret = bch2_dirent_read_target(trans, dst_dir,
 350                                 bkey_s_c_to_dirent(old_dst), dst_inum);
 351                 if (ret)
 352                         goto out;
 353
 354                 dst_type = bkey_s_c_to_dirent(old_dst).v->d_type;
 355
 356                 if (dst_type == DT_SUBVOL)
 357                         return -EOPNOTSUPP;
 358         }
 359
 360         if (mode != BCH_RENAME_EXCHANGE)
 361                 *src_offset = dst_iter.pos.offset;
 362
 363         /* Create new dst key: */
 364         new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
 365         ret = PTR_ERR_OR_ZERO(new_dst);
 366         if (ret)
 367                 goto out;
 368
 369         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 370         new_dst->k.p = dst_iter.pos;
 371
 372         /* Create new src key: */
 373         if (mode == BCH_RENAME_EXCHANGE) {
 374                 new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
 375                 ret = PTR_ERR_OR_ZERO(new_src);
 376                 if (ret)
 377                         goto out;
 378
 379                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 380                 new_src->k.p = src_iter.pos;
 381         } else {
 382                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 383                 ret = PTR_ERR_OR_ZERO(new_src);
 384                 if (ret)
 385                         goto out;
 386
 387                 bkey_init(&new_src->k);
 388                 new_src->k.p = src_iter.pos;
 389
 390                 if (bkey_le(dst_pos, src_iter.pos) &&
 391                     bkey_lt(src_iter.pos, dst_iter.pos)) {
 392                         /*
 393                          * We have a hash collision for the new dst key,
 394                          * and new_src - the key we're deleting - is between
 395                          * new_dst's hashed slot and the slot we're going to be
 396                          * inserting it into - oops.  This will break the hash
 397                          * table if we don't deal with it:
 398                          */
 399                         if (mode == BCH_RENAME) {
 400                                 /*
 401                                  * If we're not overwriting, we can just insert
 402                                  * new_dst at the src position:
 403                                  */
 404                                 new_src = new_dst;
 405                                 new_src->k.p = src_iter.pos;
 406                                 goto out_set_src;
 407                         } else {
 408                                 /* If we're overwriting, we can't insert new_dst
 409                                  * at a different slot because it has to
 410                                  * overwrite old_dst - just make sure to use a
 411                                  * whiteout when deleting src:
 412                                  */
 413                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 414                         }
 415                 } else {
 416                         /* Check if we need a whiteout to delete src: */
 417                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 418                                                        src_hash, &src_iter);
 419                         if (ret < 0)
 420                                 goto out;
 421
 422                         if (ret)
 423                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 424                 }
 425         }
 426
 427         ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
 428         if (ret)
 429                 goto out;
 430 out_set_src:
 431
 432         /*
 433          * If we're deleting a subvolume, we need to really delete the dirent,
 434          * not just emit a whiteout in the current snapshot:
 435          */
 436         if (src_type == DT_SUBVOL) {
 437                 bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
 438                 ret = bch2_btree_iter_traverse(&src_iter);
 439                 if (ret)
 440                         goto out;
 441
 442                 new_src->k.p = src_iter.pos;
 443                 src_update_flags |= BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE;
 444         }
 445
 446         ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
 447         if (ret)
 448                 goto out;
 449
 450         if (mode == BCH_RENAME_EXCHANGE)
 451                 *src_offset = new_src->k.p.offset;
 452         *dst_offset = new_dst->k.p.offset;
 453 out:
 454         bch2_trans_iter_exit(trans, &src_iter);
 455         bch2_trans_iter_exit(trans, &dst_iter);
 456         return ret;
 457 }
 458
 459 int __bch2_dirent_lookup_trans(struct btree_trans *trans,
 460                                struct btree_iter *iter,
 461                                subvol_inum dir,
 462                                const struct bch_hash_info *hash_info,
 463                                const struct qstr *name, subvol_inum *inum,
 464                                unsigned flags)
 465 {
 466         struct bkey_s_c k;
 467         struct bkey_s_c_dirent d;
 468         u32 snapshot;
 469         int ret;
 470
 471         ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
 472         if (ret)
 473                 return ret;
 474
 475         ret = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
 476                                hash_info, dir, name, flags);
 477         if (ret)
 478                 return ret;
 479
 480         k = bch2_btree_iter_peek_slot(iter);
 481         ret = bkey_err(k);
 482         if (ret)
 483                 goto err;
 484
 485         d = bkey_s_c_to_dirent(k);
 486
 487         ret = bch2_dirent_read_target(trans, dir, d, inum);
 488         if (ret > 0)
 489                 ret = -ENOENT;
 490 err:
 491         if (ret)
 492                 bch2_trans_iter_exit(trans, iter);
 493
 494         return ret;
 495 }
 496
 497 u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 498                        const struct bch_hash_info *hash_info,
 499                        const struct qstr *name, subvol_inum *inum)
 500 {
 501         struct btree_trans *trans = bch2_trans_get(c);
 502         struct btree_iter iter = { NULL };
 503
 504         int ret = lockrestart_do(trans,
 505                 __bch2_dirent_lookup_trans(trans, &iter, dir, hash_info, name, inum, 0));
 506         bch2_trans_iter_exit(trans, &iter);
 507         bch2_trans_put(trans);
 508         return ret;
 509 }
 510
 511 int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32 snapshot)
 512 {
 513         struct btree_iter iter;
 514         struct bkey_s_c k;
 515         int ret;
 516
 517         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 518                            SPOS(dir, 0, snapshot),
 519                            POS(dir, U64_MAX), 0, k, ret)
 520                 if (k.k->type == KEY_TYPE_dirent) {
 521                         ret = -ENOTEMPTY;
 522                         break;
 523                 }
 524         bch2_trans_iter_exit(trans, &iter);
 525
 526         return ret;
 527 }
 528
 529 int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 530 {
 531         u32 snapshot;
 532
 533         return bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot) ?:
 534                 bch2_empty_dir_snapshot(trans, dir.inum, snapshot);
 535 }
 536
 537 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 538 {
 539         struct btree_trans *trans = bch2_trans_get(c);
 540         struct btree_iter iter;
 541         struct bkey_s_c k;
 542         struct bkey_s_c_dirent dirent;
 543         subvol_inum target;
 544         u32 snapshot;
 545         struct bkey_buf sk;
 546         struct qstr name;
 547         int ret;
 548
 549         bch2_bkey_buf_init(&sk);
 550 retry:
 551         bch2_trans_begin(trans);
 552
 553         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 554         if (ret)
 555                 goto err;
 556
 557         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 558                            SPOS(inum.inum, ctx->pos, snapshot),
 559                            POS(inum.inum, U64_MAX), 0, k, ret) {
 560                 if (k.k->type != KEY_TYPE_dirent)
 561                         continue;
 562
 563                 dirent = bkey_s_c_to_dirent(k);
 564
 565                 ret = bch2_dirent_read_target(trans, inum, dirent, &target);
 566                 if (ret < 0)
 567                         break;
 568                 if (ret)
 569                         continue;
 570
 571                 /* dir_emit() can fault and block: */
 572                 bch2_bkey_buf_reassemble(&sk, c, k);
 573                 dirent = bkey_i_to_s_c_dirent(sk.k);
 574                 bch2_trans_unlock(trans);
 575
 576                 name = bch2_dirent_get_name(dirent);
 577
 578                 ctx->pos = dirent.k->p.offset;
 579                 if (!dir_emit(ctx, name.name,
 580                               name.len,
 581                               target.inum,
 582                               vfs_d_type(dirent.v->d_type)))
 583                         break;
 584                 ctx->pos = dirent.k->p.offset + 1;
 585
 586                 /*
 587                  * read_target looks up subvolumes, we can overflow paths if the
 588                  * directory has many subvolumes in it
 589                  */
 590                 ret = btree_trans_too_many_iters(trans);
 591                 if (ret)
 592                         break;
 593         }
 594         bch2_trans_iter_exit(trans, &iter);
 595 err:
 596         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 597                 goto retry;
 598
 599         bch2_trans_put(trans);
 600         bch2_bkey_buf_exit(&sk, c);
 601
 602         return ret;
 603 }