git.sesse.net Git - bcachefs-tools-debian/blob - c_src/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 "snapshot.h"
  10 #include "subvolume.h"
  11
  12 #include <linux/random.h>
  13
  14 static int bch2_subvolume_delete(struct btree_trans *, u32);
  15
  16 static int check_subvol(struct btree_trans *trans,
  17                         struct btree_iter *iter,
  18                         struct bkey_s_c k)
  19 {
  20         struct bch_fs *c = trans->c;
  21         struct bkey_s_c_subvolume subvol;
  22         struct bch_snapshot snapshot;
  23         unsigned snapid;
  24         int ret = 0;
  25
  26         if (k.k->type != KEY_TYPE_subvolume)
  27                 return 0;
  28
  29         subvol = bkey_s_c_to_subvolume(k);
  30         snapid = le32_to_cpu(subvol.v->snapshot);
  31         ret = bch2_snapshot_lookup(trans, snapid, &snapshot);
  32
  33         if (bch2_err_matches(ret, ENOENT))
  34                 bch_err(c, "subvolume %llu points to nonexistent snapshot %u",
  35                         k.k->p.offset, snapid);
  36         if (ret)
  37                 return ret;
  38
  39         if (BCH_SUBVOLUME_UNLINKED(subvol.v)) {
  40                 ret = bch2_subvolume_delete(trans, iter->pos.offset);
  41                 bch_err_msg(c, ret, "deleting subvolume %llu", iter->pos.offset);
  42                 return ret ?: -BCH_ERR_transaction_restart_nested;
  43         }
  44
  45         if (!BCH_SUBVOLUME_SNAP(subvol.v)) {
  46                 u32 snapshot_root = bch2_snapshot_root(c, le32_to_cpu(subvol.v->snapshot));
  47                 u32 snapshot_tree;
  48                 struct bch_snapshot_tree st;
  49
  50                 rcu_read_lock();
  51                 snapshot_tree = snapshot_t(c, snapshot_root)->tree;
  52                 rcu_read_unlock();
  53
  54                 ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);
  55
  56                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
  57                                 "%s: snapshot tree %u not found", __func__, snapshot_tree);
  58
  59                 if (ret)
  60                         return ret;
  61
  62                 if (fsck_err_on(le32_to_cpu(st.master_subvol) != subvol.k->p.offset,
  63                                 c, subvol_not_master_and_not_snapshot,
  64                                 "subvolume %llu is not set as snapshot but is not master subvolume",
  65                                 k.k->p.offset)) {
  66                         struct bkey_i_subvolume *s =
  67                                 bch2_bkey_make_mut_typed(trans, iter, &subvol.s_c, 0, subvolume);
  68                         ret = PTR_ERR_OR_ZERO(s);
  69                         if (ret)
  70                                 return ret;
  71
  72                         SET_BCH_SUBVOLUME_SNAP(&s->v, true);
  73                 }
  74         }
  75
  76 fsck_err:
  77         return ret;
  78 }
  79
  80 int bch2_check_subvols(struct bch_fs *c)
  81 {
  82         int ret = bch2_trans_run(c,
  83                 for_each_btree_key_commit(trans, iter,
  84                                 BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
  85                                 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
  86                         check_subvol(trans, &iter, k)));
  87         bch_err_fn(c, ret);
  88         return ret;
  89 }
  90
  91 /* Subvolumes: */
  92
  93 int bch2_subvolume_invalid(struct bch_fs *c, struct bkey_s_c k,
  94                            enum bkey_invalid_flags flags, struct printbuf *err)
  95 {
  96         int ret = 0;
  97
  98         bkey_fsck_err_on(bkey_lt(k.k->p, SUBVOL_POS_MIN) ||
  99                          bkey_gt(k.k->p, SUBVOL_POS_MAX), c, err,
 100                          subvol_pos_bad,
 101                          "invalid pos");
 102 fsck_err:
 103         return ret;
 104 }
 105
 106 void bch2_subvolume_to_text(struct printbuf *out, struct bch_fs *c,
 107                             struct bkey_s_c k)
 108 {
 109         struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
 110
 111         prt_printf(out, "root %llu snapshot id %u",
 112                    le64_to_cpu(s.v->inode),
 113                    le32_to_cpu(s.v->snapshot));
 114
 115         if (bkey_val_bytes(s.k) > offsetof(struct bch_subvolume, parent))
 116                 prt_printf(out, " parent %u", le32_to_cpu(s.v->parent));
 117 }
 118
 119 static __always_inline int
 120 bch2_subvolume_get_inlined(struct btree_trans *trans, unsigned subvol,
 121                            bool inconsistent_if_not_found,
 122                            int iter_flags,
 123                            struct bch_subvolume *s)
 124 {
 125         int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_subvolumes, POS(0, subvol),
 126                                           iter_flags, subvolume, s);
 127         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT) &&
 128                                 inconsistent_if_not_found,
 129                                 trans->c, "missing subvolume %u", subvol);
 130         return ret;
 131 }
 132
 133 int bch2_subvolume_get(struct btree_trans *trans, unsigned subvol,
 134                        bool inconsistent_if_not_found,
 135                        int iter_flags,
 136                        struct bch_subvolume *s)
 137 {
 138         return bch2_subvolume_get_inlined(trans, subvol, inconsistent_if_not_found, iter_flags, s);
 139 }
 140
 141 int bch2_subvol_is_ro_trans(struct btree_trans *trans, u32 subvol)
 142 {
 143         struct bch_subvolume s;
 144         int ret = bch2_subvolume_get_inlined(trans, subvol, true, 0, &s);
 145         if (ret)
 146                 return ret;
 147
 148         if (BCH_SUBVOLUME_RO(&s))
 149                 return -EROFS;
 150         return 0;
 151 }
 152
 153 int bch2_subvol_is_ro(struct bch_fs *c, u32 subvol)
 154 {
 155         return bch2_trans_do(c, NULL, NULL, 0,
 156                 bch2_subvol_is_ro_trans(trans, subvol));
 157 }
 158
 159 int bch2_snapshot_get_subvol(struct btree_trans *trans, u32 snapshot,
 160                              struct bch_subvolume *subvol)
 161 {
 162         struct bch_snapshot snap;
 163
 164         return  bch2_snapshot_lookup(trans, snapshot, &snap) ?:
 165                 bch2_subvolume_get(trans, le32_to_cpu(snap.subvol), true, 0, subvol);
 166 }
 167
 168 int bch2_subvolume_get_snapshot(struct btree_trans *trans, u32 subvolid,
 169                                 u32 *snapid)
 170 {
 171         struct btree_iter iter;
 172         struct bkey_s_c_subvolume subvol;
 173         int ret;
 174
 175         subvol = bch2_bkey_get_iter_typed(trans, &iter,
 176                                           BTREE_ID_subvolumes, POS(0, subvolid),
 177                                           BTREE_ITER_CACHED|BTREE_ITER_WITH_UPDATES,
 178                                           subvolume);
 179         ret = bkey_err(subvol);
 180         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 181                                 "missing subvolume %u", subvolid);
 182
 183         if (likely(!ret))
 184                 *snapid = le32_to_cpu(subvol.v->snapshot);
 185         bch2_trans_iter_exit(trans, &iter);
 186         return ret;
 187 }
 188
 189 static int bch2_subvolume_reparent(struct btree_trans *trans,
 190                                    struct btree_iter *iter,
 191                                    struct bkey_s_c k,
 192                                    u32 old_parent, u32 new_parent)
 193 {
 194         struct bkey_i_subvolume *s;
 195         int ret;
 196
 197         if (k.k->type != KEY_TYPE_subvolume)
 198                 return 0;
 199
 200         if (bkey_val_bytes(k.k) > offsetof(struct bch_subvolume, parent) &&
 201             le32_to_cpu(bkey_s_c_to_subvolume(k).v->parent) != old_parent)
 202                 return 0;
 203
 204         s = bch2_bkey_make_mut_typed(trans, iter, &k, 0, subvolume);
 205         ret = PTR_ERR_OR_ZERO(s);
 206         if (ret)
 207                 return ret;
 208
 209         s->v.parent = cpu_to_le32(new_parent);
 210         return 0;
 211 }
 212
 213 /*
 214  * Separate from the snapshot tree in the snapshots btree, we record the tree
 215  * structure of how snapshot subvolumes were created - the parent subvolume of
 216  * each snapshot subvolume.
 217  *
 218  * When a subvolume is deleted, we scan for child subvolumes and reparant them,
 219  * to avoid dangling references:
 220  */
 221 static int bch2_subvolumes_reparent(struct btree_trans *trans, u32 subvolid_to_delete)
 222 {
 223         struct bch_subvolume s;
 224
 225         return lockrestart_do(trans,
 226                         bch2_subvolume_get(trans, subvolid_to_delete, true,
 227                                    BTREE_ITER_CACHED, &s)) ?:
 228                 for_each_btree_key_commit(trans, iter,
 229                                 BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
 230                                 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 231                         bch2_subvolume_reparent(trans, &iter, k,
 232                                         subvolid_to_delete, le32_to_cpu(s.parent)));
 233 }
 234
 235 /*
 236  * Delete subvolume, mark snapshot ID as deleted, queue up snapshot
 237  * deletion/cleanup:
 238  */
 239 static int __bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 240 {
 241         struct btree_iter iter;
 242         struct bkey_s_c_subvolume subvol;
 243         u32 snapid;
 244         int ret = 0;
 245
 246         subvol = bch2_bkey_get_iter_typed(trans, &iter,
 247                                 BTREE_ID_subvolumes, POS(0, subvolid),
 248                                 BTREE_ITER_CACHED|BTREE_ITER_INTENT,
 249                                 subvolume);
 250         ret = bkey_err(subvol);
 251         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 252                                 "missing subvolume %u", subvolid);
 253         if (ret)
 254                 return ret;
 255
 256         snapid = le32_to_cpu(subvol.v->snapshot);
 257
 258         ret =   bch2_btree_delete_at(trans, &iter, 0) ?:
 259                 bch2_snapshot_node_set_deleted(trans, snapid);
 260         bch2_trans_iter_exit(trans, &iter);
 261         return ret;
 262 }
 263
 264 static int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 265 {
 266         return bch2_subvolumes_reparent(trans, subvolid) ?:
 267                 commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 268                           __bch2_subvolume_delete(trans, subvolid));
 269 }
 270
 271 static void bch2_subvolume_wait_for_pagecache_and_delete(struct work_struct *work)
 272 {
 273         struct bch_fs *c = container_of(work, struct bch_fs,
 274                                 snapshot_wait_for_pagecache_and_delete_work);
 275         snapshot_id_list s;
 276         u32 *id;
 277         int ret = 0;
 278
 279         while (!ret) {
 280                 mutex_lock(&c->snapshots_unlinked_lock);
 281                 s = c->snapshots_unlinked;
 282                 darray_init(&c->snapshots_unlinked);
 283                 mutex_unlock(&c->snapshots_unlinked_lock);
 284
 285                 if (!s.nr)
 286                         break;
 287
 288                 bch2_evict_subvolume_inodes(c, &s);
 289
 290                 for (id = s.data; id < s.data + s.nr; id++) {
 291                         ret = bch2_trans_run(c, bch2_subvolume_delete(trans, *id));
 292                         bch_err_msg(c, ret, "deleting subvolume %u", *id);
 293                         if (ret)
 294                                 break;
 295                 }
 296
 297                 darray_exit(&s);
 298         }
 299
 300         bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
 301 }
 302
 303 struct subvolume_unlink_hook {
 304         struct btree_trans_commit_hook  h;
 305         u32                             subvol;
 306 };
 307
 308 static int bch2_subvolume_wait_for_pagecache_and_delete_hook(struct btree_trans *trans,
 309                                                       struct btree_trans_commit_hook *_h)
 310 {
 311         struct subvolume_unlink_hook *h = container_of(_h, struct subvolume_unlink_hook, h);
 312         struct bch_fs *c = trans->c;
 313         int ret = 0;
 314
 315         mutex_lock(&c->snapshots_unlinked_lock);
 316         if (!snapshot_list_has_id(&c->snapshots_unlinked, h->subvol))
 317                 ret = snapshot_list_add(c, &c->snapshots_unlinked, h->subvol);
 318         mutex_unlock(&c->snapshots_unlinked_lock);
 319
 320         if (ret)
 321                 return ret;
 322
 323         if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_snapshot_delete_pagecache))
 324                 return -EROFS;
 325
 326         if (!queue_work(c->write_ref_wq, &c->snapshot_wait_for_pagecache_and_delete_work))
 327                 bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
 328         return 0;
 329 }
 330
 331 int bch2_subvolume_unlink(struct btree_trans *trans, u32 subvolid)
 332 {
 333         struct btree_iter iter;
 334         struct bkey_i_subvolume *n;
 335         struct subvolume_unlink_hook *h;
 336         int ret = 0;
 337
 338         h = bch2_trans_kmalloc(trans, sizeof(*h));
 339         ret = PTR_ERR_OR_ZERO(h);
 340         if (ret)
 341                 return ret;
 342
 343         h->h.fn         = bch2_subvolume_wait_for_pagecache_and_delete_hook;
 344         h->subvol       = subvolid;
 345         bch2_trans_commit_hook(trans, &h->h);
 346
 347         n = bch2_bkey_get_mut_typed(trans, &iter,
 348                         BTREE_ID_subvolumes, POS(0, subvolid),
 349                         BTREE_ITER_CACHED, subvolume);
 350         ret = PTR_ERR_OR_ZERO(n);
 351         if (unlikely(ret)) {
 352                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 353                                         "missing subvolume %u", subvolid);
 354                 return ret;
 355         }
 356
 357         SET_BCH_SUBVOLUME_UNLINKED(&n->v, true);
 358         bch2_trans_iter_exit(trans, &iter);
 359         return ret;
 360 }
 361
 362 int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
 363                           u32 src_subvolid,
 364                           u32 *new_subvolid,
 365                           u32 *new_snapshotid,
 366                           bool ro)
 367 {
 368         struct bch_fs *c = trans->c;
 369         struct btree_iter dst_iter, src_iter = (struct btree_iter) { NULL };
 370         struct bkey_i_subvolume *new_subvol = NULL;
 371         struct bkey_i_subvolume *src_subvol = NULL;
 372         u32 parent = 0, new_nodes[2], snapshot_subvols[2];
 373         int ret = 0;
 374
 375         ret = bch2_bkey_get_empty_slot(trans, &dst_iter,
 376                                 BTREE_ID_subvolumes, POS(0, U32_MAX));
 377         if (ret == -BCH_ERR_ENOSPC_btree_slot)
 378                 ret = -BCH_ERR_ENOSPC_subvolume_create;
 379         if (ret)
 380                 return ret;
 381
 382         snapshot_subvols[0] = dst_iter.pos.offset;
 383         snapshot_subvols[1] = src_subvolid;
 384
 385         if (src_subvolid) {
 386                 /* Creating a snapshot: */
 387
 388                 src_subvol = bch2_bkey_get_mut_typed(trans, &src_iter,
 389                                 BTREE_ID_subvolumes, POS(0, src_subvolid),
 390                                 BTREE_ITER_CACHED, subvolume);
 391                 ret = PTR_ERR_OR_ZERO(src_subvol);
 392                 if (unlikely(ret)) {
 393                         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 394                                                 "subvolume %u not found", src_subvolid);
 395                         goto err;
 396                 }
 397
 398                 parent = le32_to_cpu(src_subvol->v.snapshot);
 399         }
 400
 401         ret = bch2_snapshot_node_create(trans, parent, new_nodes,
 402                                         snapshot_subvols,
 403                                         src_subvolid ? 2 : 1);
 404         if (ret)
 405                 goto err;
 406
 407         if (src_subvolid) {
 408                 src_subvol->v.snapshot = cpu_to_le32(new_nodes[1]);
 409                 ret = bch2_trans_update(trans, &src_iter, &src_subvol->k_i, 0);
 410                 if (ret)
 411                         goto err;
 412         }
 413
 414         new_subvol = bch2_bkey_alloc(trans, &dst_iter, 0, subvolume);
 415         ret = PTR_ERR_OR_ZERO(new_subvol);
 416         if (ret)
 417                 goto err;
 418
 419         new_subvol->v.flags     = 0;
 420         new_subvol->v.snapshot  = cpu_to_le32(new_nodes[0]);
 421         new_subvol->v.inode     = cpu_to_le64(inode);
 422         new_subvol->v.parent    = cpu_to_le32(src_subvolid);
 423         new_subvol->v.otime.lo  = cpu_to_le64(bch2_current_time(c));
 424         new_subvol->v.otime.hi  = 0;
 425
 426         SET_BCH_SUBVOLUME_RO(&new_subvol->v, ro);
 427         SET_BCH_SUBVOLUME_SNAP(&new_subvol->v, src_subvolid != 0);
 428
 429         *new_subvolid   = new_subvol->k.p.offset;
 430         *new_snapshotid = new_nodes[0];
 431 err:
 432         bch2_trans_iter_exit(trans, &src_iter);
 433         bch2_trans_iter_exit(trans, &dst_iter);
 434         return ret;
 435 }
 436
 437 int bch2_fs_subvolumes_init(struct bch_fs *c)
 438 {
 439         INIT_WORK(&c->snapshot_delete_work, bch2_delete_dead_snapshots_work);
 440         INIT_WORK(&c->snapshot_wait_for_pagecache_and_delete_work,
 441                   bch2_subvolume_wait_for_pagecache_and_delete);
 442         mutex_init(&c->snapshots_unlinked_lock);
 443         return 0;
 444 }