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 "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                 bch2_fs_lazy_rw(c);
  41
  42                 ret = bch2_subvolume_delete(trans, iter->pos.offset);
  43                 if (ret)
  44                         bch_err_msg(c, ret, "deleting subvolume %llu", iter->pos.offset);
  45                 return ret ?: -BCH_ERR_transaction_restart_nested;
  46         }
  47
  48         if (!BCH_SUBVOLUME_SNAP(subvol.v)) {
  49                 u32 snapshot_root = bch2_snapshot_root(c, le32_to_cpu(subvol.v->snapshot));
  50                 u32 snapshot_tree;
  51                 struct bch_snapshot_tree st;
  52
  53                 rcu_read_lock();
  54                 snapshot_tree = snapshot_t(c, snapshot_root)->tree;
  55                 rcu_read_unlock();
  56
  57                 ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);
  58
  59                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
  60                                 "%s: snapshot tree %u not found", __func__, snapshot_tree);
  61
  62                 if (ret)
  63                         return ret;
  64
  65                 if (fsck_err_on(le32_to_cpu(st.master_subvol) != subvol.k->p.offset,
  66                                 c, subvol_not_master_and_not_snapshot,
  67                                 "subvolume %llu is not set as snapshot but is not master subvolume",
  68                                 k.k->p.offset)) {
  69                         struct bkey_i_subvolume *s =
  70                                 bch2_bkey_make_mut_typed(trans, iter, &subvol.s_c, 0, subvolume);
  71                         ret = PTR_ERR_OR_ZERO(s);
  72                         if (ret)
  73                                 return ret;
  74
  75                         SET_BCH_SUBVOLUME_SNAP(&s->v, true);
  76                 }
  77         }
  78
  79 fsck_err:
  80         return ret;
  81 }
  82
  83 int bch2_check_subvols(struct bch_fs *c)
  84 {
  85         struct btree_iter iter;
  86         struct bkey_s_c k;
  87         int ret;
  88
  89         ret = bch2_trans_run(c,
  90                 for_each_btree_key_commit(trans, iter,
  91                         BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
  92                         NULL, NULL, BCH_TRANS_COMMIT_lazy_rw|BCH_TRANS_COMMIT_no_enospc,
  93                 check_subvol(trans, &iter, k)));
  94         if (ret)
  95                 bch_err_fn(c, ret);
  96         return ret;
  97 }
  98
  99 /* Subvolumes: */
 100
 101 int bch2_subvolume_invalid(struct bch_fs *c, struct bkey_s_c k,
 102                            enum bkey_invalid_flags flags, struct printbuf *err)
 103 {
 104         int ret = 0;
 105
 106         bkey_fsck_err_on(bkey_lt(k.k->p, SUBVOL_POS_MIN) ||
 107                          bkey_gt(k.k->p, SUBVOL_POS_MAX), c, err,
 108                          subvol_pos_bad,
 109                          "invalid pos");
 110 fsck_err:
 111         return ret;
 112 }
 113
 114 void bch2_subvolume_to_text(struct printbuf *out, struct bch_fs *c,
 115                             struct bkey_s_c k)
 116 {
 117         struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
 118
 119         prt_printf(out, "root %llu snapshot id %u",
 120                    le64_to_cpu(s.v->inode),
 121                    le32_to_cpu(s.v->snapshot));
 122
 123         if (bkey_val_bytes(s.k) > offsetof(struct bch_subvolume, parent))
 124                 prt_printf(out, " parent %u", le32_to_cpu(s.v->parent));
 125 }
 126
 127 static __always_inline int
 128 bch2_subvolume_get_inlined(struct btree_trans *trans, unsigned subvol,
 129                            bool inconsistent_if_not_found,
 130                            int iter_flags,
 131                            struct bch_subvolume *s)
 132 {
 133         int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_subvolumes, POS(0, subvol),
 134                                           iter_flags, subvolume, s);
 135         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT) &&
 136                                 inconsistent_if_not_found,
 137                                 trans->c, "missing subvolume %u", subvol);
 138         return ret;
 139 }
 140
 141 int bch2_subvolume_get(struct btree_trans *trans, unsigned subvol,
 142                        bool inconsistent_if_not_found,
 143                        int iter_flags,
 144                        struct bch_subvolume *s)
 145 {
 146         return bch2_subvolume_get_inlined(trans, subvol, inconsistent_if_not_found, iter_flags, s);
 147 }
 148
 149 int bch2_snapshot_get_subvol(struct btree_trans *trans, u32 snapshot,
 150                              struct bch_subvolume *subvol)
 151 {
 152         struct bch_snapshot snap;
 153
 154         return  bch2_snapshot_lookup(trans, snapshot, &snap) ?:
 155                 bch2_subvolume_get(trans, le32_to_cpu(snap.subvol), true, 0, subvol);
 156 }
 157
 158 int bch2_subvolume_get_snapshot(struct btree_trans *trans, u32 subvolid,
 159                                 u32 *snapid)
 160 {
 161         struct btree_iter iter;
 162         struct bkey_s_c_subvolume subvol;
 163         int ret;
 164
 165         subvol = bch2_bkey_get_iter_typed(trans, &iter,
 166                                           BTREE_ID_subvolumes, POS(0, subvolid),
 167                                           BTREE_ITER_CACHED|BTREE_ITER_WITH_UPDATES,
 168                                           subvolume);
 169         ret = bkey_err(subvol);
 170         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 171                                 "missing subvolume %u", subvolid);
 172
 173         if (likely(!ret))
 174                 *snapid = le32_to_cpu(subvol.v->snapshot);
 175         bch2_trans_iter_exit(trans, &iter);
 176         return ret;
 177 }
 178
 179 static int bch2_subvolume_reparent(struct btree_trans *trans,
 180                                    struct btree_iter *iter,
 181                                    struct bkey_s_c k,
 182                                    u32 old_parent, u32 new_parent)
 183 {
 184         struct bkey_i_subvolume *s;
 185         int ret;
 186
 187         if (k.k->type != KEY_TYPE_subvolume)
 188                 return 0;
 189
 190         if (bkey_val_bytes(k.k) > offsetof(struct bch_subvolume, parent) &&
 191             le32_to_cpu(bkey_s_c_to_subvolume(k).v->parent) != old_parent)
 192                 return 0;
 193
 194         s = bch2_bkey_make_mut_typed(trans, iter, &k, 0, subvolume);
 195         ret = PTR_ERR_OR_ZERO(s);
 196         if (ret)
 197                 return ret;
 198
 199         s->v.parent = cpu_to_le32(new_parent);
 200         return 0;
 201 }
 202
 203 /*
 204  * Separate from the snapshot tree in the snapshots btree, we record the tree
 205  * structure of how snapshot subvolumes were created - the parent subvolume of
 206  * each snapshot subvolume.
 207  *
 208  * When a subvolume is deleted, we scan for child subvolumes and reparant them,
 209  * to avoid dangling references:
 210  */
 211 static int bch2_subvolumes_reparent(struct btree_trans *trans, u32 subvolid_to_delete)
 212 {
 213         struct btree_iter iter;
 214         struct bkey_s_c k;
 215         struct bch_subvolume s;
 216
 217         return lockrestart_do(trans,
 218                         bch2_subvolume_get(trans, subvolid_to_delete, true,
 219                                    BTREE_ITER_CACHED, &s)) ?:
 220                 for_each_btree_key_commit(trans, iter,
 221                                 BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
 222                                 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 223                         bch2_subvolume_reparent(trans, &iter, k,
 224                                         subvolid_to_delete, le32_to_cpu(s.parent)));
 225 }
 226
 227 /*
 228  * Delete subvolume, mark snapshot ID as deleted, queue up snapshot
 229  * deletion/cleanup:
 230  */
 231 static int __bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 232 {
 233         struct btree_iter iter;
 234         struct bkey_s_c_subvolume subvol;
 235         u32 snapid;
 236         int ret = 0;
 237
 238         subvol = bch2_bkey_get_iter_typed(trans, &iter,
 239                                 BTREE_ID_subvolumes, POS(0, subvolid),
 240                                 BTREE_ITER_CACHED|BTREE_ITER_INTENT,
 241                                 subvolume);
 242         ret = bkey_err(subvol);
 243         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 244                                 "missing subvolume %u", subvolid);
 245         if (ret)
 246                 return ret;
 247
 248         snapid = le32_to_cpu(subvol.v->snapshot);
 249
 250         ret =   bch2_btree_delete_at(trans, &iter, 0) ?:
 251                 bch2_snapshot_node_set_deleted(trans, snapid);
 252         bch2_trans_iter_exit(trans, &iter);
 253         return ret;
 254 }
 255
 256 static int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 257 {
 258         return bch2_subvolumes_reparent(trans, subvolid) ?:
 259                 commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 260                           __bch2_subvolume_delete(trans, subvolid));
 261 }
 262
 263 static void bch2_subvolume_wait_for_pagecache_and_delete(struct work_struct *work)
 264 {
 265         struct bch_fs *c = container_of(work, struct bch_fs,
 266                                 snapshot_wait_for_pagecache_and_delete_work);
 267         snapshot_id_list s;
 268         u32 *id;
 269         int ret = 0;
 270
 271         while (!ret) {
 272                 mutex_lock(&c->snapshots_unlinked_lock);
 273                 s = c->snapshots_unlinked;
 274                 darray_init(&c->snapshots_unlinked);
 275                 mutex_unlock(&c->snapshots_unlinked_lock);
 276
 277                 if (!s.nr)
 278                         break;
 279
 280                 bch2_evict_subvolume_inodes(c, &s);
 281
 282                 for (id = s.data; id < s.data + s.nr; id++) {
 283                         ret = bch2_trans_run(c, bch2_subvolume_delete(trans, *id));
 284                         if (ret) {
 285                                 bch_err_msg(c, ret, "deleting subvolume %u", *id);
 286                                 break;
 287                         }
 288                 }
 289
 290                 darray_exit(&s);
 291         }
 292
 293         bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
 294 }
 295
 296 struct subvolume_unlink_hook {
 297         struct btree_trans_commit_hook  h;
 298         u32                             subvol;
 299 };
 300
 301 static int bch2_subvolume_wait_for_pagecache_and_delete_hook(struct btree_trans *trans,
 302                                                       struct btree_trans_commit_hook *_h)
 303 {
 304         struct subvolume_unlink_hook *h = container_of(_h, struct subvolume_unlink_hook, h);
 305         struct bch_fs *c = trans->c;
 306         int ret = 0;
 307
 308         mutex_lock(&c->snapshots_unlinked_lock);
 309         if (!snapshot_list_has_id(&c->snapshots_unlinked, h->subvol))
 310                 ret = snapshot_list_add(c, &c->snapshots_unlinked, h->subvol);
 311         mutex_unlock(&c->snapshots_unlinked_lock);
 312
 313         if (ret)
 314                 return ret;
 315
 316         if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_snapshot_delete_pagecache))
 317                 return -EROFS;
 318
 319         if (!queue_work(c->write_ref_wq, &c->snapshot_wait_for_pagecache_and_delete_work))
 320                 bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
 321         return 0;
 322 }
 323
 324 int bch2_subvolume_unlink(struct btree_trans *trans, u32 subvolid)
 325 {
 326         struct btree_iter iter;
 327         struct bkey_i_subvolume *n;
 328         struct subvolume_unlink_hook *h;
 329         int ret = 0;
 330
 331         h = bch2_trans_kmalloc(trans, sizeof(*h));
 332         ret = PTR_ERR_OR_ZERO(h);
 333         if (ret)
 334                 return ret;
 335
 336         h->h.fn         = bch2_subvolume_wait_for_pagecache_and_delete_hook;
 337         h->subvol       = subvolid;
 338         bch2_trans_commit_hook(trans, &h->h);
 339
 340         n = bch2_bkey_get_mut_typed(trans, &iter,
 341                         BTREE_ID_subvolumes, POS(0, subvolid),
 342                         BTREE_ITER_CACHED, subvolume);
 343         ret = PTR_ERR_OR_ZERO(n);
 344         if (unlikely(ret)) {
 345                 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
 346                                         "missing subvolume %u", subvolid);
 347                 return ret;
 348         }
 349
 350         SET_BCH_SUBVOLUME_UNLINKED(&n->v, true);
 351         bch2_trans_iter_exit(trans, &iter);
 352         return ret;
 353 }
 354
 355 int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
 356                           u32 src_subvolid,
 357                           u32 *new_subvolid,
 358                           u32 *new_snapshotid,
 359                           bool ro)
 360 {
 361         struct bch_fs *c = trans->c;
 362         struct btree_iter dst_iter, src_iter = (struct btree_iter) { NULL };
 363         struct bkey_i_subvolume *new_subvol = NULL;
 364         struct bkey_i_subvolume *src_subvol = NULL;
 365         u32 parent = 0, new_nodes[2], snapshot_subvols[2];
 366         int ret = 0;
 367
 368         ret = bch2_bkey_get_empty_slot(trans, &dst_iter,
 369                                 BTREE_ID_subvolumes, POS(0, U32_MAX));
 370         if (ret == -BCH_ERR_ENOSPC_btree_slot)
 371                 ret = -BCH_ERR_ENOSPC_subvolume_create;
 372         if (ret)
 373                 return ret;
 374
 375         snapshot_subvols[0] = dst_iter.pos.offset;
 376         snapshot_subvols[1] = src_subvolid;
 377
 378         if (src_subvolid) {
 379                 /* Creating a snapshot: */
 380
 381                 src_subvol = bch2_bkey_get_mut_typed(trans, &src_iter,
 382                                 BTREE_ID_subvolumes, POS(0, src_subvolid),
 383                                 BTREE_ITER_CACHED, subvolume);
 384                 ret = PTR_ERR_OR_ZERO(src_subvol);
 385                 if (unlikely(ret)) {
 386                         bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 387                                                 "subvolume %u not found", src_subvolid);
 388                         goto err;
 389                 }
 390
 391                 parent = le32_to_cpu(src_subvol->v.snapshot);
 392         }
 393
 394         ret = bch2_snapshot_node_create(trans, parent, new_nodes,
 395                                         snapshot_subvols,
 396                                         src_subvolid ? 2 : 1);
 397         if (ret)
 398                 goto err;
 399
 400         if (src_subvolid) {
 401                 src_subvol->v.snapshot = cpu_to_le32(new_nodes[1]);
 402                 ret = bch2_trans_update(trans, &src_iter, &src_subvol->k_i, 0);
 403                 if (ret)
 404                         goto err;
 405         }
 406
 407         new_subvol = bch2_bkey_alloc(trans, &dst_iter, 0, subvolume);
 408         ret = PTR_ERR_OR_ZERO(new_subvol);
 409         if (ret)
 410                 goto err;
 411
 412         new_subvol->v.flags     = 0;
 413         new_subvol->v.snapshot  = cpu_to_le32(new_nodes[0]);
 414         new_subvol->v.inode     = cpu_to_le64(inode);
 415         new_subvol->v.parent    = cpu_to_le32(src_subvolid);
 416         new_subvol->v.otime.lo  = cpu_to_le64(bch2_current_time(c));
 417         new_subvol->v.otime.hi  = 0;
 418
 419         SET_BCH_SUBVOLUME_RO(&new_subvol->v, ro);
 420         SET_BCH_SUBVOLUME_SNAP(&new_subvol->v, src_subvolid != 0);
 421
 422         *new_subvolid   = new_subvol->k.p.offset;
 423         *new_snapshotid = new_nodes[0];
 424 err:
 425         bch2_trans_iter_exit(trans, &src_iter);
 426         bch2_trans_iter_exit(trans, &dst_iter);
 427         return ret;
 428 }
 429
 430 int bch2_fs_subvolumes_init(struct bch_fs *c)
 431 {
 432         INIT_WORK(&c->snapshot_delete_work, bch2_delete_dead_snapshots_work);
 433         INIT_WORK(&c->snapshot_wait_for_pagecache_and_delete_work,
 434                   bch2_subvolume_wait_for_pagecache_and_delete);
 435         mutex_init(&c->snapshots_unlinked_lock);
 436         return 0;
 437 }