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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "btree_key_cache.h"
   5 #include "btree_update.h"
   6 #include "errcode.h"
   7 #include "error.h"
   8 #include "fs.h"
   9 #include "subvolume.h"
  10
  11 static int bch2_subvolume_delete(struct btree_trans *, u32);
  12
  13 /* Snapshot tree: */
  14
  15 void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c,
  16                                 struct bkey_s_c k)
  17 {
  18         struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k);
  19
  20         prt_printf(out, "subvol %u root snapshot %u",
  21                    le32_to_cpu(t.v->master_subvol),
  22                    le32_to_cpu(t.v->root_snapshot));
  23 }
  24
  25 int bch2_snapshot_tree_invalid(const struct bch_fs *c, struct bkey_s_c k,
  26                                enum bkey_invalid_flags flags,
  27                                struct printbuf *err)
  28 {
  29         if (bkey_gt(k.k->p, POS(0, U32_MAX)) ||
  30             bkey_lt(k.k->p, POS(0, 1))) {
  31                 prt_printf(err, "bad pos");
  32                 return -BCH_ERR_invalid_bkey;
  33         }
  34
  35         return 0;
  36 }
  37
  38 int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id,
  39                               struct bch_snapshot_tree *s)
  40 {
  41         int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id),
  42                                           BTREE_ITER_WITH_UPDATES, snapshot_tree, s);
  43
  44         if (bch2_err_matches(ret, ENOENT))
  45                 ret = -BCH_ERR_ENOENT_snapshot_tree;
  46         return ret;
  47 }
  48
  49 static struct bkey_i_snapshot_tree *
  50 __snapshot_tree_create(struct btree_trans *trans)
  51 {
  52         struct btree_iter iter;
  53         int ret = bch2_bkey_get_empty_slot(trans, &iter,
  54                         BTREE_ID_snapshot_trees, POS(0, U32_MAX));
  55         struct bkey_i_snapshot_tree *s_t;
  56
  57         if (ret == -BCH_ERR_ENOSPC_btree_slot)
  58                 ret = -BCH_ERR_ENOSPC_snapshot_tree;
  59         if (ret)
  60                 return ERR_PTR(ret);
  61
  62         s_t = bch2_bkey_alloc(trans, &iter, 0, snapshot_tree);
  63         ret = PTR_ERR_OR_ZERO(s_t);
  64         bch2_trans_iter_exit(trans, &iter);
  65         return ret ? ERR_PTR(ret) : s_t;
  66 }
  67
  68 static int snapshot_tree_create(struct btree_trans *trans,
  69                                 u32 root_id, u32 subvol_id, u32 *tree_id)
  70 {
  71         struct bkey_i_snapshot_tree *n_tree =
  72                 __snapshot_tree_create(trans);
  73
  74         if (IS_ERR(n_tree))
  75                 return PTR_ERR(n_tree);
  76
  77         n_tree->v.master_subvol = cpu_to_le32(subvol_id);
  78         n_tree->v.root_snapshot = cpu_to_le32(root_id);
  79         *tree_id = n_tree->k.p.offset;
  80         return 0;
  81 }
  82
  83 /* Snapshot nodes: */
  84
  85 void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,
  86                            struct bkey_s_c k)
  87 {
  88         struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);
  89
  90         prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u",
  91                BCH_SNAPSHOT_SUBVOL(s.v),
  92                BCH_SNAPSHOT_DELETED(s.v),
  93                le32_to_cpu(s.v->parent),
  94                le32_to_cpu(s.v->children[0]),
  95                le32_to_cpu(s.v->children[1]),
  96                le32_to_cpu(s.v->subvol),
  97                le32_to_cpu(s.v->tree));
  98 }
  99
 100 int bch2_snapshot_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_snapshot s;
 105         u32 i, id;
 106
 107         if (bkey_gt(k.k->p, POS(0, U32_MAX)) ||
 108             bkey_lt(k.k->p, POS(0, 1))) {
 109                 prt_printf(err, "bad pos");
 110                 return -BCH_ERR_invalid_bkey;
 111         }
 112
 113         s = bkey_s_c_to_snapshot(k);
 114
 115         id = le32_to_cpu(s.v->parent);
 116         if (id && id <= k.k->p.offset) {
 117                 prt_printf(err, "bad parent node (%u <= %llu)",
 118                        id, k.k->p.offset);
 119                 return -BCH_ERR_invalid_bkey;
 120         }
 121
 122         if (le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1])) {
 123                 prt_printf(err, "children not normalized");
 124                 return -BCH_ERR_invalid_bkey;
 125         }
 126
 127         if (s.v->children[0] &&
 128             s.v->children[0] == s.v->children[1]) {
 129                 prt_printf(err, "duplicate child nodes");
 130                 return -BCH_ERR_invalid_bkey;
 131         }
 132
 133         for (i = 0; i < 2; i++) {
 134                 id = le32_to_cpu(s.v->children[i]);
 135
 136                 if (id >= k.k->p.offset) {
 137                         prt_printf(err, "bad child node (%u >= %llu)",
 138                                id, k.k->p.offset);
 139                         return -BCH_ERR_invalid_bkey;
 140                 }
 141         }
 142
 143         return 0;
 144 }
 145
 146 int bch2_mark_snapshot(struct btree_trans *trans,
 147                        enum btree_id btree, unsigned level,
 148                        struct bkey_s_c old, struct bkey_s_c new,
 149                        unsigned flags)
 150 {
 151         struct bch_fs *c = trans->c;
 152         struct snapshot_t *t;
 153
 154         t = genradix_ptr_alloc(&c->snapshots,
 155                                U32_MAX - new.k->p.offset,
 156                                GFP_KERNEL);
 157         if (!t)
 158                 return -BCH_ERR_ENOMEM_mark_snapshot;
 159
 160         if (new.k->type == KEY_TYPE_snapshot) {
 161                 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);
 162
 163                 t->parent       = le32_to_cpu(s.v->parent);
 164                 t->children[0]  = le32_to_cpu(s.v->children[0]);
 165                 t->children[1]  = le32_to_cpu(s.v->children[1]);
 166                 t->subvol       = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0;
 167                 t->tree         = le32_to_cpu(s.v->tree);
 168         } else {
 169                 t->parent       = 0;
 170                 t->children[0]  = 0;
 171                 t->children[1]  = 0;
 172                 t->subvol       = 0;
 173                 t->tree         = 0;
 174         }
 175
 176         return 0;
 177 }
 178
 179 static int snapshot_lookup(struct btree_trans *trans, u32 id,
 180                            struct bch_snapshot *s)
 181 {
 182         return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id),
 183                                        BTREE_ITER_WITH_UPDATES, snapshot, s);
 184 }
 185
 186 static int snapshot_live(struct btree_trans *trans, u32 id)
 187 {
 188         struct bch_snapshot v;
 189         int ret;
 190
 191         if (!id)
 192                 return 0;
 193
 194         ret = snapshot_lookup(trans, id, &v);
 195         if (bch2_err_matches(ret, ENOENT))
 196                 bch_err(trans->c, "snapshot node %u not found", id);
 197         if (ret)
 198                 return ret;
 199
 200         return !BCH_SNAPSHOT_DELETED(&v);
 201 }
 202
 203 static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
 204 {
 205         struct bch_fs *c = trans->c;
 206         unsigned i, nr_live = 0, live_idx = 0;
 207         struct bkey_s_c_snapshot snap;
 208         u32 id = k.k->p.offset, child[2];
 209
 210         if (k.k->type != KEY_TYPE_snapshot)
 211                 return 0;
 212
 213         snap = bkey_s_c_to_snapshot(k);
 214
 215         child[0] = le32_to_cpu(snap.v->children[0]);
 216         child[1] = le32_to_cpu(snap.v->children[1]);
 217
 218         for (i = 0; i < 2; i++) {
 219                 int ret = snapshot_live(trans, child[i]);
 220
 221                 if (ret < 0)
 222                         return ret;
 223
 224                 if (ret)
 225                         live_idx = i;
 226                 nr_live += ret;
 227         }
 228
 229         snapshot_t(c, id)->equiv = nr_live == 1
 230                 ? snapshot_t(c, child[live_idx])->equiv
 231                 : id;
 232         return 0;
 233 }
 234
 235 /* fsck: */
 236
 237 static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child)
 238 {
 239         return snapshot_t(c, id)->children[child];
 240 }
 241
 242 static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id)
 243 {
 244         return bch2_snapshot_child(c, id, 0);
 245 }
 246
 247 static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id)
 248 {
 249         return bch2_snapshot_child(c, id, 1);
 250 }
 251
 252 static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id)
 253 {
 254         u32 n, parent;
 255
 256         n = bch2_snapshot_left_child(c, id);
 257         if (n)
 258                 return n;
 259
 260         while ((parent = bch2_snapshot_parent(c, id))) {
 261                 n = bch2_snapshot_right_child(c, parent);
 262                 if (n && n != id)
 263                         return n;
 264                 id = parent;
 265         }
 266
 267         return 0;
 268 }
 269
 270 static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root)
 271 {
 272         u32 id = snapshot_root;
 273         u32 subvol = 0, s;
 274
 275         while (id) {
 276                 s = snapshot_t(c, id)->subvol;
 277
 278                 if (s && (!subvol || s < subvol))
 279                         subvol = s;
 280
 281                 id = bch2_snapshot_tree_next(c, id);
 282         }
 283
 284         return subvol;
 285 }
 286
 287 static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans,
 288                                             u32 snapshot_root, u32 *subvol_id)
 289 {
 290         struct bch_fs *c = trans->c;
 291         struct btree_iter iter;
 292         struct bkey_s_c k;
 293         struct bkey_s_c_subvolume s;
 294         bool found = false;
 295         int ret;
 296
 297         for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,
 298                                      0, k, ret) {
 299                 if (k.k->type != KEY_TYPE_subvolume)
 300                         continue;
 301
 302                 s = bkey_s_c_to_subvolume(k);
 303                 if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root))
 304                         continue;
 305                 if (!BCH_SUBVOLUME_SNAP(s.v)) {
 306                         *subvol_id = s.k->p.offset;
 307                         found = true;
 308                         break;
 309                 }
 310         }
 311
 312         bch2_trans_iter_exit(trans, &iter);
 313
 314         if (!ret && !found) {
 315                 struct bkey_i_subvolume *s;
 316
 317                 *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root);
 318
 319                 s = bch2_bkey_get_mut_typed(trans, &iter,
 320                                             BTREE_ID_subvolumes, POS(0, *subvol_id),
 321                                             0, subvolume);
 322                 ret = PTR_ERR_OR_ZERO(s);
 323                 if (ret)
 324                         return ret;
 325
 326                 SET_BCH_SUBVOLUME_SNAP(&s->v, false);
 327         }
 328
 329         return ret;
 330 }
 331
 332 static int check_snapshot_tree(struct btree_trans *trans,
 333                                struct btree_iter *iter,
 334                                struct bkey_s_c k)
 335 {
 336         struct bch_fs *c = trans->c;
 337         struct bkey_s_c_snapshot_tree st;
 338         struct bch_snapshot s;
 339         struct bch_subvolume subvol;
 340         struct printbuf buf = PRINTBUF;
 341         u32 root_id;
 342         int ret;
 343
 344         if (k.k->type != KEY_TYPE_snapshot_tree)
 345                 return 0;
 346
 347         st = bkey_s_c_to_snapshot_tree(k);
 348         root_id = le32_to_cpu(st.v->root_snapshot);
 349
 350         ret = snapshot_lookup(trans, root_id, &s);
 351         if (ret && !bch2_err_matches(ret, ENOENT))
 352                 goto err;
 353
 354         if (fsck_err_on(ret ||
 355                         root_id != bch2_snapshot_root(c, root_id) ||
 356                         st.k->p.offset != le32_to_cpu(s.tree),
 357                         c,
 358                         "snapshot tree points to missing/incorrect snapshot:\n  %s",
 359                         (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
 360                 ret = bch2_btree_delete_at(trans, iter, 0);
 361                 goto err;
 362         }
 363
 364         ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol),
 365                                  false, 0, &subvol);
 366         if (ret && !bch2_err_matches(ret, ENOENT))
 367                 goto err;
 368
 369         if (fsck_err_on(ret, c,
 370                         "snapshot tree points to missing subvolume:\n  %s",
 371                         (printbuf_reset(&buf),
 372                          bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
 373             fsck_err_on(!bch2_snapshot_is_ancestor(c,
 374                                                    le32_to_cpu(subvol.snapshot),
 375                                                    root_id), c,
 376                         "snapshot tree points to subvolume that does not point to snapshot in this tree:\n  %s",
 377                         (printbuf_reset(&buf),
 378                          bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
 379             fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol), c,
 380                         "snapshot tree points to snapshot subvolume:\n  %s",
 381                         (printbuf_reset(&buf),
 382                          bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
 383                 struct bkey_i_snapshot_tree *u;
 384                 u32 subvol_id;
 385
 386                 ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id);
 387                 if (ret)
 388                         goto err;
 389
 390                 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree);
 391                 ret = PTR_ERR_OR_ZERO(u);
 392                 if (ret)
 393                         goto err;
 394
 395                 u->v.master_subvol = cpu_to_le32(subvol_id);
 396                 st = snapshot_tree_i_to_s_c(u);
 397         }
 398 err:
 399 fsck_err:
 400         printbuf_exit(&buf);
 401         return ret;
 402 }
 403
 404 /*
 405  * For each snapshot_tree, make sure it points to the root of a snapshot tree
 406  * and that snapshot entry points back to it, or delete it.
 407  *
 408  * And, make sure it points to a subvolume within that snapshot tree, or correct
 409  * it to point to the oldest subvolume within that snapshot tree.
 410  */
 411 int bch2_fs_check_snapshot_trees(struct bch_fs *c)
 412 {
 413         struct btree_iter iter;
 414         struct bkey_s_c k;
 415         int ret;
 416
 417         ret = bch2_trans_run(c,
 418                 for_each_btree_key_commit(&trans, iter,
 419                         BTREE_ID_snapshot_trees, POS_MIN,
 420                         BTREE_ITER_PREFETCH, k,
 421                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 422                 check_snapshot_tree(&trans, &iter, k)));
 423
 424         if (ret)
 425                 bch_err(c, "error %i checking snapshot trees", ret);
 426         return ret;
 427 }
 428
 429 /*
 430  * Look up snapshot tree for @tree_id and find root,
 431  * make sure @snap_id is a descendent:
 432  */
 433 static int snapshot_tree_ptr_good(struct btree_trans *trans,
 434                                   u32 snap_id, u32 tree_id)
 435 {
 436         struct bch_snapshot_tree s_t;
 437         int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
 438
 439         if (bch2_err_matches(ret, ENOENT))
 440                 return 0;
 441         if (ret)
 442                 return ret;
 443
 444         return bch2_snapshot_is_ancestor(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot));
 445 }
 446
 447 /*
 448  * snapshot_tree pointer was incorrect: look up root snapshot node, make sure
 449  * its snapshot_tree pointer is correct (allocate new one if necessary), then
 450  * update this node's pointer to root node's pointer:
 451  */
 452 static int snapshot_tree_ptr_repair(struct btree_trans *trans,
 453                                     struct btree_iter *iter,
 454                                     struct bkey_s_c_snapshot *s)
 455 {
 456         struct bch_fs *c = trans->c;
 457         struct btree_iter root_iter;
 458         struct bch_snapshot_tree s_t;
 459         struct bkey_s_c_snapshot root;
 460         struct bkey_i_snapshot *u;
 461         u32 root_id = bch2_snapshot_root(c, s->k->p.offset), tree_id;
 462         int ret;
 463
 464         root = bch2_bkey_get_iter_typed(trans, &root_iter,
 465                                BTREE_ID_snapshots, POS(0, root_id),
 466                                BTREE_ITER_WITH_UPDATES, snapshot);
 467         ret = bkey_err(root);
 468         if (ret)
 469                 goto err;
 470
 471         tree_id = le32_to_cpu(root.v->tree);
 472
 473         ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
 474         if (ret && !bch2_err_matches(ret, ENOENT))
 475                 return ret;
 476
 477         if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) {
 478                 u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot);
 479                 ret =   PTR_ERR_OR_ZERO(u) ?:
 480                         snapshot_tree_create(trans, root_id,
 481                                 bch2_snapshot_tree_oldest_subvol(c, root_id),
 482                                 &tree_id);
 483                 if (ret)
 484                         goto err;
 485
 486                 u->v.tree = cpu_to_le32(tree_id);
 487                 if (s->k->p.snapshot == root_id)
 488                         *s = snapshot_i_to_s_c(u);
 489         }
 490
 491         if (s->k->p.snapshot != root_id) {
 492                 u = bch2_bkey_make_mut_typed(trans, iter, &s->s_c, 0, snapshot);
 493                 ret = PTR_ERR_OR_ZERO(u);
 494                 if (ret)
 495                         goto err;
 496
 497                 u->v.tree = cpu_to_le32(tree_id);
 498                 *s = snapshot_i_to_s_c(u);
 499         }
 500 err:
 501         bch2_trans_iter_exit(trans, &root_iter);
 502         return ret;
 503 }
 504
 505 static int check_snapshot(struct btree_trans *trans,
 506                           struct btree_iter *iter,
 507                           struct bkey_s_c k)
 508 {
 509         struct bch_fs *c = trans->c;
 510         struct bkey_s_c_snapshot s;
 511         struct bch_subvolume subvol;
 512         struct bch_snapshot v;
 513         struct printbuf buf = PRINTBUF;
 514         bool should_have_subvol;
 515         u32 i, id;
 516         int ret = 0;
 517
 518         if (k.k->type != KEY_TYPE_snapshot)
 519                 return 0;
 520
 521         s = bkey_s_c_to_snapshot(k);
 522         id = le32_to_cpu(s.v->parent);
 523         if (id) {
 524                 ret = snapshot_lookup(trans, id, &v);
 525                 if (bch2_err_matches(ret, ENOENT))
 526                         bch_err(c, "snapshot with nonexistent parent:\n  %s",
 527                                 (bch2_bkey_val_to_text(&buf, c, s.s_c), buf.buf));
 528                 if (ret)
 529                         goto err;
 530
 531                 if (le32_to_cpu(v.children[0]) != s.k->p.offset &&
 532                     le32_to_cpu(v.children[1]) != s.k->p.offset) {
 533                         bch_err(c, "snapshot parent %u missing pointer to child %llu",
 534                                 id, s.k->p.offset);
 535                         ret = -EINVAL;
 536                         goto err;
 537                 }
 538         }
 539
 540         for (i = 0; i < 2 && s.v->children[i]; i++) {
 541                 id = le32_to_cpu(s.v->children[i]);
 542
 543                 ret = snapshot_lookup(trans, id, &v);
 544                 if (bch2_err_matches(ret, ENOENT))
 545                         bch_err(c, "snapshot node %llu has nonexistent child %u",
 546                                 s.k->p.offset, id);
 547                 if (ret)
 548                         goto err;
 549
 550                 if (le32_to_cpu(v.parent) != s.k->p.offset) {
 551                         bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)",
 552                                 id, le32_to_cpu(v.parent), s.k->p.offset);
 553                         ret = -EINVAL;
 554                         goto err;
 555                 }
 556         }
 557
 558         should_have_subvol = BCH_SNAPSHOT_SUBVOL(s.v) &&
 559                 !BCH_SNAPSHOT_DELETED(s.v);
 560
 561         if (should_have_subvol) {
 562                 id = le32_to_cpu(s.v->subvol);
 563                 ret = bch2_subvolume_get(trans, id, 0, false, &subvol);
 564                 if (bch2_err_matches(ret, ENOENT))
 565                         bch_err(c, "snapshot points to nonexistent subvolume:\n  %s",
 566                                 (bch2_bkey_val_to_text(&buf, c, s.s_c), buf.buf));
 567                 if (ret)
 568                         goto err;
 569
 570                 if (BCH_SNAPSHOT_SUBVOL(s.v) != (le32_to_cpu(subvol.snapshot) == s.k->p.offset)) {
 571                         bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
 572                                 s.k->p.offset);
 573                         ret = -EINVAL;
 574                         goto err;
 575                 }
 576         } else {
 577                 if (fsck_err_on(s.v->subvol, c, "snapshot should not point to subvol:\n  %s",
 578                                 (bch2_bkey_val_to_text(&buf, c, s.s_c), buf.buf))) {
 579                         struct bkey_i_snapshot *u = bch2_trans_kmalloc(trans, sizeof(*u));
 580
 581                         ret = PTR_ERR_OR_ZERO(u);
 582                         if (ret)
 583                                 goto err;
 584
 585                         bkey_reassemble(&u->k_i, s.s_c);
 586                         u->v.subvol = 0;
 587                         ret = bch2_trans_update(trans, iter, &u->k_i, 0);
 588                         if (ret)
 589                                 goto err;
 590
 591                         s = snapshot_i_to_s_c(u);
 592                 }
 593         }
 594
 595         ret = snapshot_tree_ptr_good(trans, s.k->p.offset, le32_to_cpu(s.v->tree));
 596         if (ret < 0)
 597                 goto err;
 598
 599         if (fsck_err_on(!ret, c, "snapshot points to missing/incorrect tree:\n  %s",
 600                         (bch2_bkey_val_to_text(&buf, c, s.s_c), buf.buf))) {
 601                 ret = snapshot_tree_ptr_repair(trans, iter, &s);
 602                 if (ret)
 603                         goto err;
 604         }
 605         ret = 0;
 606
 607         if (BCH_SNAPSHOT_DELETED(s.v))
 608                 set_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags);
 609 err:
 610 fsck_err:
 611         printbuf_exit(&buf);
 612         return ret;
 613 }
 614
 615 int bch2_fs_check_snapshots(struct bch_fs *c)
 616 {
 617         struct btree_iter iter;
 618         struct bkey_s_c k;
 619         int ret;
 620
 621         ret = bch2_trans_run(c,
 622                 for_each_btree_key_commit(&trans, iter,
 623                         BTREE_ID_snapshots, POS_MIN,
 624                         BTREE_ITER_PREFETCH, k,
 625                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 626                 check_snapshot(&trans, &iter, k)));
 627         if (ret)
 628                 bch_err_fn(c, ret);
 629         return ret;
 630 }
 631
 632 static int check_subvol(struct btree_trans *trans,
 633                         struct btree_iter *iter,
 634                         struct bkey_s_c k)
 635 {
 636         struct bch_fs *c = trans->c;
 637         struct bkey_s_c_subvolume subvol;
 638         struct bch_snapshot snapshot;
 639         unsigned snapid;
 640         int ret = 0;
 641
 642         if (k.k->type != KEY_TYPE_subvolume)
 643                 return 0;
 644
 645         subvol = bkey_s_c_to_subvolume(k);
 646         snapid = le32_to_cpu(subvol.v->snapshot);
 647         ret = snapshot_lookup(trans, snapid, &snapshot);
 648
 649         if (bch2_err_matches(ret, ENOENT))
 650                 bch_err(c, "subvolume %llu points to nonexistent snapshot %u",
 651                         k.k->p.offset, snapid);
 652         if (ret)
 653                 return ret;
 654
 655         if (BCH_SUBVOLUME_UNLINKED(subvol.v)) {
 656                 bch2_fs_lazy_rw(c);
 657
 658                 ret = bch2_subvolume_delete(trans, iter->pos.offset);
 659                 if (ret)
 660                         bch_err(c, "error deleting subvolume %llu: %s",
 661                                 iter->pos.offset, bch2_err_str(ret));
 662                 return ret ?: -BCH_ERR_transaction_restart_nested;
 663         }
 664
 665         if (!BCH_SUBVOLUME_SNAP(subvol.v)) {
 666                 u32 snapshot_root = bch2_snapshot_root(c, le32_to_cpu(subvol.v->snapshot));
 667                 u32 snapshot_tree = snapshot_t(c, snapshot_root)->tree;
 668                 struct bch_snapshot_tree st;
 669
 670                 ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);
 671
 672                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 673                                 "%s: snapshot tree %u not found", __func__, snapshot_tree);
 674
 675                 if (ret)
 676                         return ret;
 677
 678                 if (fsck_err_on(le32_to_cpu(st.master_subvol) != subvol.k->p.offset, c,
 679                                 "subvolume %llu is not set as snapshot but is not master subvolume",
 680                                 k.k->p.offset)) {
 681                         struct bkey_i_subvolume *s =
 682                                 bch2_bkey_make_mut_typed(trans, iter, &subvol.s_c, 0, subvolume);
 683                         ret = PTR_ERR_OR_ZERO(s);
 684                         if (ret)
 685                                 return ret;
 686
 687                         SET_BCH_SUBVOLUME_SNAP(&s->v, true);
 688                 }
 689         }
 690
 691 fsck_err:
 692         return ret;
 693 }
 694
 695 int bch2_fs_check_subvols(struct bch_fs *c)
 696 {
 697         struct btree_iter iter;
 698         struct bkey_s_c k;
 699         int ret;
 700
 701         ret = bch2_trans_run(c,
 702                 for_each_btree_key_commit(&trans, iter,
 703                         BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
 704                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 705                 check_subvol(&trans, &iter, k)));
 706         if (ret)
 707                 bch_err_fn(c, ret);
 708         return ret;
 709 }
 710
 711 void bch2_fs_snapshots_exit(struct bch_fs *c)
 712 {
 713         genradix_free(&c->snapshots);
 714 }
 715
 716 int bch2_fs_snapshots_start(struct bch_fs *c)
 717 {
 718         struct btree_iter iter;
 719         struct bkey_s_c k;
 720         int ret = 0;
 721
 722         ret = bch2_trans_run(c,
 723                 for_each_btree_key2(&trans, iter, BTREE_ID_snapshots,
 724                            POS_MIN, 0, k,
 725                         bch2_mark_snapshot(&trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?:
 726                         bch2_snapshot_set_equiv(&trans, k)));
 727         if (ret)
 728                 bch_err_fn(c, ret);
 729         return ret;
 730 }
 731
 732 /*
 733  * Mark a snapshot as deleted, for future cleanup:
 734  */
 735 static int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
 736 {
 737         struct btree_iter iter;
 738         struct bkey_i_snapshot *s;
 739         int ret = 0;
 740
 741         s = bch2_bkey_get_mut_typed(trans, &iter,
 742                                     BTREE_ID_snapshots, POS(0, id),
 743                                     0, snapshot);
 744         ret = PTR_ERR_OR_ZERO(s);
 745         if (unlikely(ret)) {
 746                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),
 747                                         trans->c, "missing snapshot %u", id);
 748                 return ret;
 749         }
 750
 751         /* already deleted? */
 752         if (BCH_SNAPSHOT_DELETED(&s->v))
 753                 goto err;
 754
 755         SET_BCH_SNAPSHOT_DELETED(&s->v, true);
 756         SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
 757         s->v.subvol = 0;
 758 err:
 759         bch2_trans_iter_exit(trans, &iter);
 760         return ret;
 761 }
 762
 763 static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)
 764 {
 765         struct bch_fs *c = trans->c;
 766         struct btree_iter iter, p_iter = (struct btree_iter) { NULL };
 767         struct btree_iter tree_iter = (struct btree_iter) { NULL };
 768         struct bkey_s_c_snapshot s;
 769         u32 parent_id;
 770         unsigned i;
 771         int ret = 0;
 772
 773         s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id),
 774                                      BTREE_ITER_INTENT, snapshot);
 775         ret = bkey_err(s);
 776         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 777                                 "missing snapshot %u", id);
 778
 779         if (ret)
 780                 goto err;
 781
 782         BUG_ON(!BCH_SNAPSHOT_DELETED(s.v));
 783         parent_id = le32_to_cpu(s.v->parent);
 784
 785         if (parent_id) {
 786                 struct bkey_i_snapshot *parent;
 787
 788                 parent = bch2_bkey_get_mut_typed(trans, &p_iter,
 789                                      BTREE_ID_snapshots, POS(0, parent_id),
 790                                      0, snapshot);
 791                 ret = PTR_ERR_OR_ZERO(parent);
 792                 if (unlikely(ret)) {
 793                         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 794                                                 "missing snapshot %u", parent_id);
 795                         goto err;
 796                 }
 797
 798                 for (i = 0; i < 2; i++)
 799                         if (le32_to_cpu(parent->v.children[i]) == id)
 800                                 break;
 801
 802                 if (i == 2)
 803                         bch_err(c, "snapshot %u missing child pointer to %u",
 804                                 parent_id, id);
 805                 else
 806                         parent->v.children[i] = 0;
 807
 808                 if (le32_to_cpu(parent->v.children[0]) <
 809                     le32_to_cpu(parent->v.children[1]))
 810                         swap(parent->v.children[0],
 811                              parent->v.children[1]);
 812         } else {
 813                 /*
 814                  * We're deleting the root of a snapshot tree: update the
 815                  * snapshot_tree entry to point to the new root, or delete it if
 816                  * this is the last snapshot ID in this tree:
 817                  */
 818                 struct bkey_i_snapshot_tree *s_t;
 819
 820                 BUG_ON(s.v->children[1]);
 821
 822                 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter,
 823                                 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)),
 824                                 0, snapshot_tree);
 825                 ret = PTR_ERR_OR_ZERO(s_t);
 826                 if (ret)
 827                         goto err;
 828
 829                 if (s.v->children[0]) {
 830                         s_t->v.root_snapshot = s.v->children[0];
 831                 } else {
 832                         s_t->k.type = KEY_TYPE_deleted;
 833                         set_bkey_val_u64s(&s_t->k, 0);
 834                 }
 835         }
 836
 837         ret = bch2_btree_delete_at(trans, &iter, 0);
 838 err:
 839         bch2_trans_iter_exit(trans, &tree_iter);
 840         bch2_trans_iter_exit(trans, &p_iter);
 841         bch2_trans_iter_exit(trans, &iter);
 842         return ret;
 843 }
 844
 845 static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
 846                           u32 *new_snapids,
 847                           u32 *snapshot_subvols,
 848                           unsigned nr_snapids)
 849 {
 850         struct btree_iter iter;
 851         struct bkey_i_snapshot *n;
 852         struct bkey_s_c k;
 853         unsigned i;
 854         int ret;
 855
 856         bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
 857                              POS_MIN, BTREE_ITER_INTENT);
 858         k = bch2_btree_iter_peek(&iter);
 859         ret = bkey_err(k);
 860         if (ret)
 861                 goto err;
 862
 863         for (i = 0; i < nr_snapids; i++) {
 864                 k = bch2_btree_iter_prev_slot(&iter);
 865                 ret = bkey_err(k);
 866                 if (ret)
 867                         goto err;
 868
 869                 if (!k.k || !k.k->p.offset) {
 870                         ret = -BCH_ERR_ENOSPC_snapshot_create;
 871                         goto err;
 872                 }
 873
 874                 n = bch2_bkey_alloc(trans, &iter, 0, snapshot);
 875                 ret = PTR_ERR_OR_ZERO(n);
 876                 if (ret)
 877                         goto err;
 878
 879                 n->v.flags      = 0;
 880                 n->v.parent     = cpu_to_le32(parent);
 881                 n->v.subvol     = cpu_to_le32(snapshot_subvols[i]);
 882                 n->v.tree       = cpu_to_le32(tree);
 883                 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);
 884
 885                 ret = bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
 886                                          bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);
 887                 if (ret)
 888                         goto err;
 889
 890                 new_snapids[i]  = iter.pos.offset;
 891         }
 892 err:
 893         bch2_trans_iter_exit(trans, &iter);
 894         return ret;
 895 }
 896
 897 /*
 898  * Create new snapshot IDs as children of an existing snapshot ID:
 899  */
 900 static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent,
 901                               u32 *new_snapids,
 902                               u32 *snapshot_subvols,
 903                               unsigned nr_snapids)
 904 {
 905         struct btree_iter iter;
 906         struct bkey_i_snapshot *n_parent;
 907         int ret = 0;
 908
 909         n_parent = bch2_bkey_get_mut_typed(trans, &iter,
 910                         BTREE_ID_snapshots, POS(0, parent),
 911                         0, snapshot);
 912         ret = PTR_ERR_OR_ZERO(n_parent);
 913         if (unlikely(ret)) {
 914                 if (bch2_err_matches(ret, ENOENT))
 915                         bch_err(trans->c, "snapshot %u not found", parent);
 916                 return ret;
 917         }
 918
 919         if (n_parent->v.children[0] || n_parent->v.children[1]) {
 920                 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children");
 921                 ret = -EINVAL;
 922                 goto err;
 923         }
 924
 925         ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree),
 926                              new_snapids, snapshot_subvols, nr_snapids);
 927         if (ret)
 928                 goto err;
 929
 930         n_parent->v.children[0] = cpu_to_le32(new_snapids[0]);
 931         n_parent->v.children[1] = cpu_to_le32(new_snapids[1]);
 932         n_parent->v.subvol = 0;
 933         SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false);
 934 err:
 935         bch2_trans_iter_exit(trans, &iter);
 936         return ret;
 937 }
 938
 939 /*
 940  * Create a snapshot node that is the root of a new tree:
 941  */
 942 static int bch2_snapshot_node_create_tree(struct btree_trans *trans,
 943                               u32 *new_snapids,
 944                               u32 *snapshot_subvols,
 945                               unsigned nr_snapids)
 946 {
 947         struct bkey_i_snapshot_tree *n_tree;
 948         int ret;
 949
 950         n_tree = __snapshot_tree_create(trans);
 951         ret =   PTR_ERR_OR_ZERO(n_tree) ?:
 952                 create_snapids(trans, 0, n_tree->k.p.offset,
 953                              new_snapids, snapshot_subvols, nr_snapids);
 954         if (ret)
 955                 return ret;
 956
 957         n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]);
 958         n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]);
 959         return 0;
 960 }
 961
 962 int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
 963                               u32 *new_snapids,
 964                               u32 *snapshot_subvols,
 965                               unsigned nr_snapids)
 966 {
 967         BUG_ON((parent == 0) != (nr_snapids == 1));
 968         BUG_ON((parent != 0) != (nr_snapids == 2));
 969
 970         return parent
 971                 ? bch2_snapshot_node_create_children(trans, parent,
 972                                 new_snapids, snapshot_subvols, nr_snapids)
 973                 : bch2_snapshot_node_create_tree(trans,
 974                                 new_snapids, snapshot_subvols, nr_snapids);
 975
 976 }
 977
 978 static int snapshot_delete_key(struct btree_trans *trans,
 979                                struct btree_iter *iter,
 980                                struct bkey_s_c k,
 981                                snapshot_id_list *deleted,
 982                                snapshot_id_list *equiv_seen,
 983                                struct bpos *last_pos)
 984 {
 985         struct bch_fs *c = trans->c;
 986         u32 equiv = snapshot_t(c, k.k->p.snapshot)->equiv;
 987
 988         if (!bkey_eq(k.k->p, *last_pos))
 989                 equiv_seen->nr = 0;
 990         *last_pos = k.k->p;
 991
 992         if (snapshot_list_has_id(deleted, k.k->p.snapshot) ||
 993             snapshot_list_has_id(equiv_seen, equiv)) {
 994                 return bch2_btree_delete_at(trans, iter,
 995                                             BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 996         } else {
 997                 return snapshot_list_add(c, equiv_seen, equiv);
 998         }
 999 }
1000
1001 static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct btree_iter *iter,
1002                                           struct bkey_s_c k)
1003 {
1004         struct bkey_s_c_snapshot snap;
1005         u32 children[2];
1006         int ret;
1007
1008         if (k.k->type != KEY_TYPE_snapshot)
1009                 return 0;
1010
1011         snap = bkey_s_c_to_snapshot(k);
1012         if (BCH_SNAPSHOT_DELETED(snap.v) ||
1013             BCH_SNAPSHOT_SUBVOL(snap.v))
1014                 return 0;
1015
1016         children[0] = le32_to_cpu(snap.v->children[0]);
1017         children[1] = le32_to_cpu(snap.v->children[1]);
1018
1019         ret   = snapshot_live(trans, children[0]) ?:
1020                 snapshot_live(trans, children[1]);
1021         if (ret < 0)
1022                 return ret;
1023
1024         if (!ret)
1025                 return bch2_snapshot_node_set_deleted(trans, k.k->p.offset);
1026         return 0;
1027 }
1028
1029 int bch2_delete_dead_snapshots(struct bch_fs *c)
1030 {
1031         struct btree_trans trans;
1032         struct btree_iter iter;
1033         struct bkey_s_c k;
1034         struct bkey_s_c_snapshot snap;
1035         snapshot_id_list deleted = { 0 };
1036         u32 i, id;
1037         int ret = 0;
1038
1039         if (!test_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags))
1040                 return 0;
1041
1042         if (!test_bit(BCH_FS_STARTED, &c->flags)) {
1043                 ret = bch2_fs_read_write_early(c);
1044                 if (ret) {
1045                         bch_err(c, "error deleleting dead snapshots: error going rw: %s", bch2_err_str(ret));
1046                         return ret;
1047                 }
1048         }
1049
1050         bch2_trans_init(&trans, c, 0, 0);
1051
1052         /*
1053          * For every snapshot node: If we have no live children and it's not
1054          * pointed to by a subvolume, delete it:
1055          */
1056         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_snapshots,
1057                         POS_MIN, 0, k,
1058                         NULL, NULL, 0,
1059                 bch2_delete_redundant_snapshot(&trans, &iter, k));
1060         if (ret) {
1061                 bch_err(c, "error deleting redundant snapshots: %s", bch2_err_str(ret));
1062                 goto err;
1063         }
1064
1065         for_each_btree_key2(&trans, iter, BTREE_ID_snapshots,
1066                            POS_MIN, 0, k,
1067                 bch2_snapshot_set_equiv(&trans, k));
1068         if (ret) {
1069                 bch_err(c, "error in bch2_snapshots_set_equiv: %s", bch2_err_str(ret));
1070                 goto err;
1071         }
1072
1073         for_each_btree_key(&trans, iter, BTREE_ID_snapshots,
1074                            POS_MIN, 0, k, ret) {
1075                 if (k.k->type != KEY_TYPE_snapshot)
1076                         continue;
1077
1078                 snap = bkey_s_c_to_snapshot(k);
1079                 if (BCH_SNAPSHOT_DELETED(snap.v)) {
1080                         ret = snapshot_list_add(c, &deleted, k.k->p.offset);
1081                         if (ret)
1082                                 break;
1083                 }
1084         }
1085         bch2_trans_iter_exit(&trans, &iter);
1086
1087         if (ret) {
1088                 bch_err(c, "error walking snapshots: %s", bch2_err_str(ret));
1089                 goto err;
1090         }
1091
1092         for (id = 0; id < BTREE_ID_NR; id++) {
1093                 struct bpos last_pos = POS_MIN;
1094                 snapshot_id_list equiv_seen = { 0 };
1095
1096                 if (!btree_type_has_snapshots(id))
1097                         continue;
1098
1099                 ret = for_each_btree_key_commit(&trans, iter,
1100                                 id, POS_MIN,
1101                                 BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
1102                                 NULL, NULL, BTREE_INSERT_NOFAIL,
1103                         snapshot_delete_key(&trans, &iter, k, &deleted, &equiv_seen, &last_pos));
1104
1105                 darray_exit(&equiv_seen);
1106
1107                 if (ret) {
1108                         bch_err(c, "error deleting snapshot keys: %s", bch2_err_str(ret));
1109                         goto err;
1110                 }
1111         }
1112
1113         for (i = 0; i < deleted.nr; i++) {
1114                 ret = commit_do(&trans, NULL, NULL, 0,
1115                         bch2_snapshot_node_delete(&trans, deleted.data[i]));
1116                 if (ret) {
1117                         bch_err(c, "error deleting snapshot %u: %s",
1118                                 deleted.data[i], bch2_err_str(ret));
1119                         goto err;
1120                 }
1121         }
1122
1123         clear_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags);
1124 err:
1125         darray_exit(&deleted);
1126         bch2_trans_exit(&trans);
1127         if (ret)
1128                 bch_err_fn(c, ret);
1129         return ret;
1130 }
1131
1132 static void bch2_delete_dead_snapshots_work(struct work_struct *work)
1133 {
1134         struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work);
1135
1136         bch2_delete_dead_snapshots(c);
1137         bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1138 }
1139
1140 void bch2_delete_dead_snapshots_async(struct bch_fs *c)
1141 {
1142         if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) &&
1143             !queue_work(c->write_ref_wq, &c->snapshot_delete_work))
1144                 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1145 }
1146
1147 static int bch2_delete_dead_snapshots_hook(struct btree_trans *trans,
1148                                            struct btree_trans_commit_hook *h)
1149 {
1150         struct bch_fs *c = trans->c;
1151
1152         set_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags);
1153
1154         if (!test_bit(BCH_FS_FSCK_DONE, &c->flags))
1155                 return 0;
1156
1157         bch2_delete_dead_snapshots_async(c);
1158         return 0;
1159 }
1160
1161 /* Subvolumes: */
1162
1163 int bch2_subvolume_invalid(const struct bch_fs *c, struct bkey_s_c k,
1164                            unsigned flags, struct printbuf *err)
1165 {
1166         if (bkey_lt(k.k->p, SUBVOL_POS_MIN) ||
1167             bkey_gt(k.k->p, SUBVOL_POS_MAX)) {
1168                 prt_printf(err, "invalid pos");
1169                 return -BCH_ERR_invalid_bkey;
1170         }
1171
1172         return 0;
1173 }
1174
1175 void bch2_subvolume_to_text(struct printbuf *out, struct bch_fs *c,
1176                             struct bkey_s_c k)
1177 {
1178         struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
1179
1180         prt_printf(out, "root %llu snapshot id %u",
1181                    le64_to_cpu(s.v->inode),
1182                    le32_to_cpu(s.v->snapshot));
1183
1184         if (bkey_val_bytes(s.k) > offsetof(struct bch_subvolume, parent))
1185                 prt_printf(out, " parent %u", le32_to_cpu(s.v->parent));
1186 }
1187
1188 static __always_inline int
1189 bch2_subvolume_get_inlined(struct btree_trans *trans, unsigned subvol,
1190                            bool inconsistent_if_not_found,
1191                            int iter_flags,
1192                            struct bch_subvolume *s)
1193 {
1194         int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_subvolumes, POS(0, subvol),
1195                                           iter_flags, subvolume, s);
1196         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT) &&
1197                                 inconsistent_if_not_found,
1198                                 trans->c, "missing subvolume %u", subvol);
1199         return ret;
1200 }
1201
1202 int bch2_subvolume_get(struct btree_trans *trans, unsigned subvol,
1203                        bool inconsistent_if_not_found,
1204                        int iter_flags,
1205                        struct bch_subvolume *s)
1206 {
1207         return bch2_subvolume_get_inlined(trans, subvol, inconsistent_if_not_found, iter_flags, s);
1208 }
1209
1210 int bch2_snapshot_get_subvol(struct btree_trans *trans, u32 snapshot,
1211                              struct bch_subvolume *subvol)
1212 {
1213         struct bch_snapshot snap;
1214
1215         return  snapshot_lookup(trans, snapshot, &snap) ?:
1216                 bch2_subvolume_get(trans, le32_to_cpu(snap.subvol), true, 0, subvol);
1217 }
1218
1219 int bch2_subvolume_get_snapshot(struct btree_trans *trans, u32 subvol,
1220                                 u32 *snapid)
1221 {
1222         struct btree_iter iter;
1223         struct bkey_s_c k;
1224         int ret;
1225
1226         k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_subvolumes, POS(0, subvol),
1227                                BTREE_ITER_CACHED|
1228                                BTREE_ITER_WITH_UPDATES);
1229         ret = bkey_err(k) ?: k.k->type == KEY_TYPE_subvolume ? 0 : -BCH_ERR_ENOENT_subvolume;
1230
1231         if (likely(!ret))
1232                 *snapid = le32_to_cpu(bkey_s_c_to_subvolume(k).v->snapshot);
1233         else if (bch2_err_matches(ret, ENOENT))
1234                 bch2_fs_inconsistent(trans->c, "missing subvolume %u", subvol);
1235         bch2_trans_iter_exit(trans, &iter);
1236         return ret;
1237 }
1238
1239 static int bch2_subvolume_reparent(struct btree_trans *trans,
1240                                    struct btree_iter *iter,
1241                                    struct bkey_s_c k,
1242                                    u32 old_parent, u32 new_parent)
1243 {
1244         struct bkey_i_subvolume *s;
1245         int ret;
1246
1247         if (k.k->type != KEY_TYPE_subvolume)
1248                 return 0;
1249
1250         if (bkey_val_bytes(k.k) > offsetof(struct bch_subvolume, parent) &&
1251             le32_to_cpu(bkey_s_c_to_subvolume(k).v->parent) != old_parent)
1252                 return 0;
1253
1254         s = bch2_bkey_make_mut_typed(trans, iter, &k, 0, subvolume);
1255         ret = PTR_ERR_OR_ZERO(s);
1256         if (ret)
1257                 return ret;
1258
1259         s->v.parent = cpu_to_le32(new_parent);
1260         return 0;
1261 }
1262
1263 /*
1264  * Scan for subvolumes with parent @subvolid_to_delete, reparent:
1265  */
1266 static int bch2_subvolumes_reparent(struct btree_trans *trans, u32 subvolid_to_delete)
1267 {
1268         struct btree_iter iter;
1269         struct bkey_s_c k;
1270         struct bch_subvolume s;
1271
1272         return lockrestart_do(trans,
1273                         bch2_subvolume_get(trans, subvolid_to_delete, true,
1274                                    BTREE_ITER_CACHED, &s)) ?:
1275                 for_each_btree_key_commit(trans, iter,
1276                                 BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
1277                                 NULL, NULL, BTREE_INSERT_NOFAIL,
1278                         bch2_subvolume_reparent(trans, &iter, k,
1279                                         subvolid_to_delete, le32_to_cpu(s.parent)));
1280 }
1281
1282 /*
1283  * Delete subvolume, mark snapshot ID as deleted, queue up snapshot
1284  * deletion/cleanup:
1285  */
1286 static int __bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
1287 {
1288         struct btree_iter iter;
1289         struct bkey_s_c_subvolume subvol;
1290         struct btree_trans_commit_hook *h;
1291         u32 snapid;
1292         int ret = 0;
1293
1294         subvol = bch2_bkey_get_iter_typed(trans, &iter,
1295                                 BTREE_ID_subvolumes, POS(0, subvolid),
1296                                 BTREE_ITER_CACHED|BTREE_ITER_INTENT,
1297                                 subvolume);
1298         ret = bkey_err(subvol);
1299         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
1300                                 "missing subvolume %u", subvolid);
1301         if (ret)
1302                 return ret;
1303
1304         snapid = le32_to_cpu(subvol.v->snapshot);
1305
1306         ret = bch2_btree_delete_at(trans, &iter, 0);
1307         if (ret)
1308                 goto err;
1309
1310         ret = bch2_snapshot_node_set_deleted(trans, snapid);
1311         if (ret)
1312                 goto err;
1313
1314         h = bch2_trans_kmalloc(trans, sizeof(*h));
1315         ret = PTR_ERR_OR_ZERO(h);
1316         if (ret)
1317                 goto err;
1318
1319         h->fn = bch2_delete_dead_snapshots_hook;
1320         bch2_trans_commit_hook(trans, h);
1321 err:
1322         bch2_trans_iter_exit(trans, &iter);
1323         return ret;
1324 }
1325
1326 static int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
1327 {
1328         return bch2_subvolumes_reparent(trans, subvolid) ?:
1329                 commit_do(trans, NULL, NULL, BTREE_INSERT_NOFAIL,
1330                           __bch2_subvolume_delete(trans, subvolid));
1331 }
1332
1333 static void bch2_subvolume_wait_for_pagecache_and_delete(struct work_struct *work)
1334 {
1335         struct bch_fs *c = container_of(work, struct bch_fs,
1336                                 snapshot_wait_for_pagecache_and_delete_work);
1337         snapshot_id_list s;
1338         u32 *id;
1339         int ret = 0;
1340
1341         while (!ret) {
1342                 mutex_lock(&c->snapshots_unlinked_lock);
1343                 s = c->snapshots_unlinked;
1344                 darray_init(&c->snapshots_unlinked);
1345                 mutex_unlock(&c->snapshots_unlinked_lock);
1346
1347                 if (!s.nr)
1348                         break;
1349
1350                 bch2_evict_subvolume_inodes(c, &s);
1351
1352                 for (id = s.data; id < s.data + s.nr; id++) {
1353                         ret = bch2_trans_run(c, bch2_subvolume_delete(&trans, *id));
1354                         if (ret) {
1355                                 bch_err(c, "error deleting subvolume %u: %s", *id, bch2_err_str(ret));
1356                                 break;
1357                         }
1358                 }
1359
1360                 darray_exit(&s);
1361         }
1362
1363         bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
1364 }
1365
1366 struct subvolume_unlink_hook {
1367         struct btree_trans_commit_hook  h;
1368         u32                             subvol;
1369 };
1370
1371 static int bch2_subvolume_wait_for_pagecache_and_delete_hook(struct btree_trans *trans,
1372                                                       struct btree_trans_commit_hook *_h)
1373 {
1374         struct subvolume_unlink_hook *h = container_of(_h, struct subvolume_unlink_hook, h);
1375         struct bch_fs *c = trans->c;
1376         int ret = 0;
1377
1378         mutex_lock(&c->snapshots_unlinked_lock);
1379         if (!snapshot_list_has_id(&c->snapshots_unlinked, h->subvol))
1380                 ret = snapshot_list_add(c, &c->snapshots_unlinked, h->subvol);
1381         mutex_unlock(&c->snapshots_unlinked_lock);
1382
1383         if (ret)
1384                 return ret;
1385
1386         if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_snapshot_delete_pagecache))
1387                 return -EROFS;
1388
1389         if (!queue_work(c->write_ref_wq, &c->snapshot_wait_for_pagecache_and_delete_work))
1390                 bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
1391         return 0;
1392 }
1393
1394 int bch2_subvolume_unlink(struct btree_trans *trans, u32 subvolid)
1395 {
1396         struct btree_iter iter;
1397         struct bkey_i_subvolume *n;
1398         struct subvolume_unlink_hook *h;
1399         int ret = 0;
1400
1401         h = bch2_trans_kmalloc(trans, sizeof(*h));
1402         ret = PTR_ERR_OR_ZERO(h);
1403         if (ret)
1404                 return ret;
1405
1406         h->h.fn         = bch2_subvolume_wait_for_pagecache_and_delete_hook;
1407         h->subvol       = subvolid;
1408         bch2_trans_commit_hook(trans, &h->h);
1409
1410         n = bch2_bkey_get_mut_typed(trans, &iter,
1411                         BTREE_ID_subvolumes, POS(0, subvolid),
1412                         BTREE_ITER_CACHED, subvolume);
1413         ret = PTR_ERR_OR_ZERO(n);
1414         if (unlikely(ret)) {
1415                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
1416                                         "missing subvolume %u", subvolid);
1417                 return ret;
1418         }
1419
1420         SET_BCH_SUBVOLUME_UNLINKED(&n->v, true);
1421         bch2_trans_iter_exit(trans, &iter);
1422         return ret;
1423 }
1424
1425 int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
1426                           u32 src_subvolid,
1427                           u32 *new_subvolid,
1428                           u32 *new_snapshotid,
1429                           bool ro)
1430 {
1431         struct bch_fs *c = trans->c;
1432         struct btree_iter dst_iter, src_iter = (struct btree_iter) { NULL };
1433         struct bkey_i_subvolume *new_subvol = NULL;
1434         struct bkey_i_subvolume *src_subvol = NULL;
1435         u32 parent = 0, new_nodes[2], snapshot_subvols[2];
1436         int ret = 0;
1437
1438         ret = bch2_bkey_get_empty_slot(trans, &dst_iter,
1439                                 BTREE_ID_subvolumes, POS(0, U32_MAX));
1440         if (ret == -BCH_ERR_ENOSPC_btree_slot)
1441                 ret = -BCH_ERR_ENOSPC_subvolume_create;
1442         if (ret)
1443                 return ret;
1444
1445         snapshot_subvols[0] = dst_iter.pos.offset;
1446         snapshot_subvols[1] = src_subvolid;
1447
1448         if (src_subvolid) {
1449                 /* Creating a snapshot: */
1450
1451                 src_subvol = bch2_bkey_get_mut_typed(trans, &src_iter,
1452                                 BTREE_ID_subvolumes, POS(0, src_subvolid),
1453                                 BTREE_ITER_CACHED, subvolume);
1454                 ret = PTR_ERR_OR_ZERO(src_subvol);
1455                 if (unlikely(ret)) {
1456                         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
1457                                                 "subvolume %u not found", src_subvolid);
1458                         goto err;
1459                 }
1460
1461                 parent = le32_to_cpu(src_subvol->v.snapshot);
1462         }
1463
1464         ret = bch2_snapshot_node_create(trans, parent, new_nodes,
1465                                         snapshot_subvols,
1466                                         src_subvolid ? 2 : 1);
1467         if (ret)
1468                 goto err;
1469
1470         if (src_subvolid) {
1471                 src_subvol->v.snapshot = cpu_to_le32(new_nodes[1]);
1472                 ret = bch2_trans_update(trans, &src_iter, &src_subvol->k_i, 0);
1473                 if (ret)
1474                         goto err;
1475         }
1476
1477         new_subvol = bch2_bkey_alloc(trans, &dst_iter, 0, subvolume);
1478         ret = PTR_ERR_OR_ZERO(new_subvol);
1479         if (ret)
1480                 goto err;
1481
1482         new_subvol->v.flags     = 0;
1483         new_subvol->v.snapshot  = cpu_to_le32(new_nodes[0]);
1484         new_subvol->v.inode     = cpu_to_le64(inode);
1485         new_subvol->v.parent    = cpu_to_le32(src_subvolid);
1486         new_subvol->v.otime.lo  = cpu_to_le64(bch2_current_time(c));
1487         new_subvol->v.otime.hi  = 0;
1488
1489         SET_BCH_SUBVOLUME_RO(&new_subvol->v, ro);
1490         SET_BCH_SUBVOLUME_SNAP(&new_subvol->v, src_subvolid != 0);
1491
1492         *new_subvolid   = new_subvol->k.p.offset;
1493         *new_snapshotid = new_nodes[0];
1494 err:
1495         bch2_trans_iter_exit(trans, &src_iter);
1496         bch2_trans_iter_exit(trans, &dst_iter);
1497         return ret;
1498 }
1499
1500 int bch2_fs_subvolumes_init(struct bch_fs *c)
1501 {
1502         INIT_WORK(&c->snapshot_delete_work, bch2_delete_dead_snapshots_work);
1503         INIT_WORK(&c->snapshot_wait_for_pagecache_and_delete_work,
1504                   bch2_subvolume_wait_for_pagecache_and_delete);
1505         mutex_init(&c->snapshots_unlinked_lock);
1506         return 0;
1507 }