]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/recovery.c
Update bcachefs sources to fd381c355c bcachefs: Fix a null ptr deref in fsck check_ex...
[bcachefs-tools-debian] / libbcachefs / recovery.c
index d70fa968db50d95c5fa63ced0c8080e14434d903..91a66b5916eb7ed0d2629c0ee64424678ae7ec3b 100644 (file)
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include "bcachefs.h"
+#include "backpointers.h"
+#include "bkey_buf.h"
 #include "alloc_background.h"
 #include "btree_gc.h"
 #include "btree_update.h"
 #include "buckets.h"
 #include "dirent.h"
 #include "ec.h"
+#include "errcode.h"
 #include "error.h"
 #include "fs-common.h"
 #include "fsck.h"
 #include "journal_io.h"
 #include "journal_reclaim.h"
 #include "journal_seq_blacklist.h"
+#include "lru.h"
+#include "move.h"
 #include "quota.h"
 #include "recovery.h"
 #include "replicas.h"
+#include "subvolume.h"
 #include "super-io.h"
 
 #include <linux/sort.h>
 
 #define QSTR(n) { { { .len = strlen(n) } }, .name = n }
 
+/* for -o reconstruct_alloc: */
+static void drop_alloc_keys(struct journal_keys *keys)
+{
+       size_t src, dst;
+
+       for (src = 0, dst = 0; src < keys->nr; src++)
+               if (keys->d[src].btree_id != BTREE_ID_alloc)
+                       keys->d[dst++] = keys->d[src];
+
+       keys->nr = dst;
+}
+
+/*
+ * Btree node pointers have a field to stack a pointer to the in memory btree
+ * node; we need to zero out this field when reading in btree nodes, or when
+ * reading in keys from the journal:
+ */
+static void zero_out_btree_mem_ptr(struct journal_keys *keys)
+{
+       struct journal_key *i;
+
+       for (i = keys->d; i < keys->d + keys->nr; i++)
+               if (i->k->k.type == KEY_TYPE_btree_ptr_v2)
+                       bkey_i_to_btree_ptr_v2(i->k)->v.mem_ptr = 0;
+}
+
 /* iterate over keys read from the journal: */
 
-static struct journal_key *journal_key_search(struct journal_keys *journal_keys,
-                                             enum btree_id id, unsigned level,
-                                             struct bpos pos)
+static int __journal_key_cmp(enum btree_id     l_btree_id,
+                            unsigned           l_level,
+                            struct bpos        l_pos,
+                            const struct journal_key *r)
+{
+       return (cmp_int(l_btree_id,     r->btree_id) ?:
+               cmp_int(l_level,        r->level) ?:
+               bpos_cmp(l_pos, r->k->k.p));
+}
+
+static int journal_key_cmp(const struct journal_key *l, const struct journal_key *r)
+{
+       return __journal_key_cmp(l->btree_id, l->level, l->k->k.p, r);
+}
+
+static inline size_t idx_to_pos(struct journal_keys *keys, size_t idx)
 {
-       size_t l = 0, r = journal_keys->nr, m;
+       size_t gap_size = keys->size - keys->nr;
+
+       if (idx >= keys->gap)
+               idx += gap_size;
+       return idx;
+}
+
+static inline struct journal_key *idx_to_key(struct journal_keys *keys, size_t idx)
+{
+       return keys->d + idx_to_pos(keys, idx);
+}
+
+static size_t __bch2_journal_key_search(struct journal_keys *keys,
+                                       enum btree_id id, unsigned level,
+                                       struct bpos pos)
+{
+       size_t l = 0, r = keys->nr, m;
 
        while (l < r) {
                m = l + ((r - l) >> 1);
-               if ((cmp_int(id,        journal_keys->d[m].btree_id) ?:
-                    cmp_int(level,     journal_keys->d[m].level) ?:
-                    bkey_cmp(pos,      journal_keys->d[m].k->k.p)) > 0)
+               if (__journal_key_cmp(id, level, pos, idx_to_key(keys, m)) > 0)
                        l = m + 1;
                else
                        r = m;
        }
 
-       BUG_ON(l < journal_keys->nr &&
-              (cmp_int(id,     journal_keys->d[l].btree_id) ?:
-               cmp_int(level,  journal_keys->d[l].level) ?:
-               bkey_cmp(pos,   journal_keys->d[l].k->k.p)) > 0);
+       BUG_ON(l < keys->nr &&
+              __journal_key_cmp(id, level, pos, idx_to_key(keys, l)) > 0);
 
        BUG_ON(l &&
-              (cmp_int(id,     journal_keys->d[l - 1].btree_id) ?:
-               cmp_int(level,  journal_keys->d[l - 1].level) ?:
-               bkey_cmp(pos,   journal_keys->d[l - 1].k->k.p)) <= 0);
+              __journal_key_cmp(id, level, pos, idx_to_key(keys, l - 1)) <= 0);
 
-       return l < journal_keys->nr ? journal_keys->d + l : NULL;
+       return l;
 }
 
-static struct bkey_i *bch2_journal_iter_peek(struct journal_iter *iter)
+static size_t bch2_journal_key_search(struct journal_keys *keys,
+                                     enum btree_id id, unsigned level,
+                                     struct bpos pos)
 {
-       if (iter->k &&
-           iter->k < iter->keys->d + iter->keys->nr &&
-           iter->k->btree_id   == iter->btree_id &&
-           iter->k->level      == iter->level)
-               return iter->k->k;
-
-       iter->k = NULL;
-       return NULL;
+       return idx_to_pos(keys, __bch2_journal_key_search(keys, id, level, pos));
 }
 
-static void bch2_journal_iter_advance(struct journal_iter *iter)
+struct bkey_i *bch2_journal_keys_peek_upto(struct bch_fs *c, enum btree_id btree_id,
+                                          unsigned level, struct bpos pos,
+                                          struct bpos end_pos, size_t *idx)
 {
-       if (iter->k)
-               iter->k++;
+       struct journal_keys *keys = &c->journal_keys;
+       unsigned iters = 0;
+       struct journal_key *k;
+search:
+       if (!*idx)
+               *idx = __bch2_journal_key_search(keys, btree_id, level, pos);
+
+       while ((k = *idx < keys->nr ? idx_to_key(keys, *idx) : NULL)) {
+               if (__journal_key_cmp(btree_id, level, end_pos, k) < 0)
+                       return NULL;
+
+               if (__journal_key_cmp(btree_id, level, pos, k) <= 0 &&
+                   !k->overwritten)
+                       return k->k;
+
+               (*idx)++;
+               iters++;
+               if (iters == 10) {
+                       *idx = 0;
+                       goto search;
+               }
+       }
+
+       return NULL;
 }
 
-static void bch2_journal_iter_init(struct journal_iter *iter,
-                                  struct journal_keys *journal_keys,
-                                  enum btree_id id, unsigned level,
-                                  struct bpos pos)
+struct bkey_i *bch2_journal_keys_peek_slot(struct bch_fs *c, enum btree_id btree_id,
+                                          unsigned level, struct bpos pos)
 {
-       iter->btree_id  = id;
-       iter->level     = level;
-       iter->keys      = journal_keys;
-       iter->k         = journal_key_search(journal_keys, id, level, pos);
+       size_t idx = 0;
+
+       return bch2_journal_keys_peek_upto(c, btree_id, level, pos, pos, &idx);
 }
 
-static struct bkey_s_c bch2_journal_iter_peek_btree(struct btree_and_journal_iter *iter)
+static void journal_iters_fix(struct bch_fs *c)
 {
-       return iter->btree
-               ? bch2_btree_iter_peek(iter->btree)
-               : bch2_btree_node_iter_peek_unpack(&iter->node_iter,
-                                                  iter->b, &iter->unpacked);
+       struct journal_keys *keys = &c->journal_keys;
+       /* The key we just inserted is immediately before the gap: */
+       size_t gap_end = keys->gap + (keys->size - keys->nr);
+       struct btree_and_journal_iter *iter;
+
+       /*
+        * If an iterator points one after the key we just inserted, decrement
+        * the iterator so it points at the key we just inserted - if the
+        * decrement was unnecessary, bch2_btree_and_journal_iter_peek() will
+        * handle that:
+        */
+       list_for_each_entry(iter, &c->journal_iters, journal.list)
+               if (iter->journal.idx == gap_end)
+                       iter->journal.idx = keys->gap - 1;
 }
 
-static void bch2_journal_iter_advance_btree(struct btree_and_journal_iter *iter)
+static void journal_iters_move_gap(struct bch_fs *c, size_t old_gap, size_t new_gap)
 {
-       if (iter->btree)
-               bch2_btree_iter_next(iter->btree);
-       else
-               bch2_btree_node_iter_advance(&iter->node_iter, iter->b);
+       struct journal_keys *keys = &c->journal_keys;
+       struct journal_iter *iter;
+       size_t gap_size = keys->size - keys->nr;
+
+       list_for_each_entry(iter, &c->journal_iters, list) {
+               if (iter->idx > old_gap)
+                       iter->idx -= gap_size;
+               if (iter->idx >= new_gap)
+                       iter->idx += gap_size;
+       }
 }
 
-void bch2_btree_and_journal_iter_advance(struct btree_and_journal_iter *iter)
+int bch2_journal_key_insert_take(struct bch_fs *c, enum btree_id id,
+                                unsigned level, struct bkey_i *k)
 {
-       switch (iter->last) {
-       case none:
-               break;
-       case btree:
-               bch2_journal_iter_advance_btree(iter);
-               break;
-       case journal:
-               bch2_journal_iter_advance(&iter->journal);
-               break;
+       struct journal_key n = {
+               .btree_id       = id,
+               .level          = level,
+               .k              = k,
+               .allocated      = true,
+               /*
+                * Ensure these keys are done last by journal replay, to unblock
+                * journal reclaim:
+                */
+               .journal_seq    = U32_MAX,
+       };
+       struct journal_keys *keys = &c->journal_keys;
+       size_t idx = bch2_journal_key_search(keys, id, level, k->k.p);
+
+       BUG_ON(test_bit(BCH_FS_RW, &c->flags));
+
+       if (idx < keys->size &&
+           journal_key_cmp(&n, &keys->d[idx]) == 0) {
+               if (keys->d[idx].allocated)
+                       kfree(keys->d[idx].k);
+               keys->d[idx] = n;
+               return 0;
        }
 
-       iter->last = none;
-}
+       if (idx > keys->gap)
+               idx -= keys->size - keys->nr;
 
-struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *iter)
-{
-       struct bkey_s_c ret;
+       if (keys->nr == keys->size) {
+               struct journal_keys new_keys = {
+                       .nr                     = keys->nr,
+                       .size                   = max_t(size_t, keys->size, 8) * 2,
+               };
 
-       while (1) {
-               struct bkey_s_c btree_k         =
-                       bch2_journal_iter_peek_btree(iter);
-               struct bkey_s_c journal_k       =
-                       bkey_i_to_s_c(bch2_journal_iter_peek(&iter->journal));
+               new_keys.d = kvmalloc_array(new_keys.size, sizeof(new_keys.d[0]), GFP_KERNEL);
+               if (!new_keys.d) {
+                       bch_err(c, "%s: error allocating new key array (size %zu)",
+                               __func__, new_keys.size);
+                       return -BCH_ERR_ENOMEM_journal_key_insert;
+               }
 
-               if (btree_k.k && journal_k.k) {
-                       int cmp = bkey_cmp(btree_k.k->p, journal_k.k->p);
+               /* Since @keys was full, there was no gap: */
+               memcpy(new_keys.d, keys->d, sizeof(keys->d[0]) * keys->nr);
+               kvfree(keys->d);
+               *keys = new_keys;
 
-                       if (!cmp)
-                               bch2_journal_iter_advance_btree(iter);
+               /* And now the gap is at the end: */
+               keys->gap = keys->nr;
+       }
 
-                       iter->last = cmp < 0 ? btree : journal;
-               } else if (btree_k.k) {
-                       iter->last = btree;
-               } else if (journal_k.k) {
-                       iter->last = journal;
-               } else {
-                       iter->last = none;
-                       return bkey_s_c_null;
-               }
+       journal_iters_move_gap(c, keys->gap, idx);
 
-               ret = iter->last == journal ? journal_k : btree_k;
+       move_gap(keys->d, keys->nr, keys->size, keys->gap, idx);
+       keys->gap = idx;
 
-               if (iter->b &&
-                   bkey_cmp(ret.k->p, iter->b->data->max_key) > 0) {
-                       iter->journal.k = NULL;
-                       iter->last = none;
-                       return bkey_s_c_null;
-               }
+       keys->nr++;
+       keys->d[keys->gap++] = n;
 
-               if (!bkey_deleted(ret.k))
-                       break;
+       journal_iters_fix(c);
 
-               bch2_btree_and_journal_iter_advance(iter);
-       }
+       return 0;
+}
+
+/*
+ * Can only be used from the recovery thread while we're still RO - can't be
+ * used once we've got RW, as journal_keys is at that point used by multiple
+ * threads:
+ */
+int bch2_journal_key_insert(struct bch_fs *c, enum btree_id id,
+                           unsigned level, struct bkey_i *k)
+{
+       struct bkey_i *n;
+       int ret;
+
+       n = kmalloc(bkey_bytes(&k->k), GFP_KERNEL);
+       if (!n)
+               return -BCH_ERR_ENOMEM_journal_key_insert;
 
+       bkey_copy(n, k);
+       ret = bch2_journal_key_insert_take(c, id, level, n);
+       if (ret)
+               kfree(n);
        return ret;
 }
 
-struct bkey_s_c bch2_btree_and_journal_iter_next(struct btree_and_journal_iter *iter)
+int bch2_journal_key_delete(struct bch_fs *c, enum btree_id id,
+                           unsigned level, struct bpos pos)
 {
-       bch2_btree_and_journal_iter_advance(iter);
+       struct bkey_i whiteout;
+
+       bkey_init(&whiteout.k);
+       whiteout.k.p = pos;
 
-       return bch2_btree_and_journal_iter_peek(iter);
+       return bch2_journal_key_insert(c, id, level, &whiteout);
 }
 
-void bch2_btree_and_journal_iter_init(struct btree_and_journal_iter *iter,
-                                     struct btree_trans *trans,
-                                     struct journal_keys *journal_keys,
-                                     enum btree_id id, struct bpos pos)
+void bch2_journal_key_overwritten(struct bch_fs *c, enum btree_id btree,
+                                 unsigned level, struct bpos pos)
 {
-       memset(iter, 0, sizeof(*iter));
+       struct journal_keys *keys = &c->journal_keys;
+       size_t idx = bch2_journal_key_search(keys, btree, level, pos);
+
+       if (idx < keys->size &&
+           keys->d[idx].btree_id       == btree &&
+           keys->d[idx].level          == level &&
+           bpos_eq(keys->d[idx].k->k.p, pos))
+               keys->d[idx].overwritten = true;
+}
 
-       iter->btree = bch2_trans_get_iter(trans, id, pos, 0);
-       bch2_journal_iter_init(&iter->journal, journal_keys, id, 0, pos);
+static void bch2_journal_iter_advance(struct journal_iter *iter)
+{
+       if (iter->idx < iter->keys->size) {
+               iter->idx++;
+               if (iter->idx == iter->keys->gap)
+                       iter->idx += iter->keys->size - iter->keys->nr;
+       }
 }
 
-void bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter *iter,
-                                               struct journal_keys *journal_keys,
-                                               struct btree *b)
+struct bkey_s_c bch2_journal_iter_peek(struct journal_iter *iter)
 {
-       memset(iter, 0, sizeof(*iter));
+       struct journal_key *k = iter->keys->d + iter->idx;
 
-       iter->b = b;
-       bch2_btree_node_iter_init_from_start(&iter->node_iter, iter->b);
-       bch2_journal_iter_init(&iter->journal, journal_keys,
-                              b->c.btree_id, b->c.level, b->data->min_key);
+       while (k < iter->keys->d + iter->keys->size &&
+              k->btree_id      == iter->btree_id &&
+              k->level         == iter->level) {
+               if (!k->overwritten)
+                       return bkey_i_to_s_c(k->k);
+
+               bch2_journal_iter_advance(iter);
+               k = iter->keys->d + iter->idx;
+       }
+
+       return bkey_s_c_null;
 }
 
-/* Walk btree, overlaying keys from the journal: */
+static void bch2_journal_iter_exit(struct journal_iter *iter)
+{
+       list_del(&iter->list);
+}
 
-static int bch2_btree_and_journal_walk_recurse(struct bch_fs *c, struct btree *b,
-                               struct journal_keys *journal_keys,
-                               enum btree_id btree_id,
-                               btree_walk_node_fn node_fn,
-                               btree_walk_key_fn key_fn)
+static void bch2_journal_iter_init(struct bch_fs *c,
+                                  struct journal_iter *iter,
+                                  enum btree_id id, unsigned level,
+                                  struct bpos pos)
 {
-       struct btree_and_journal_iter iter;
-       struct bkey_s_c k;
-       int ret = 0;
+       iter->btree_id  = id;
+       iter->level     = level;
+       iter->keys      = &c->journal_keys;
+       iter->idx       = bch2_journal_key_search(&c->journal_keys, id, level, pos);
+}
 
-       bch2_btree_and_journal_iter_init_node_iter(&iter, journal_keys, b);
+static struct bkey_s_c bch2_journal_iter_peek_btree(struct btree_and_journal_iter *iter)
+{
+       return bch2_btree_node_iter_peek_unpack(&iter->node_iter,
+                                               iter->b, &iter->unpacked);
+}
 
-       while ((k = bch2_btree_and_journal_iter_peek(&iter)).k) {
-               ret = key_fn(c, btree_id, b->c.level, k);
-               if (ret)
-                       break;
+static void bch2_journal_iter_advance_btree(struct btree_and_journal_iter *iter)
+{
+       bch2_btree_node_iter_advance(&iter->node_iter, iter->b);
+}
 
-               if (b->c.level) {
-                       struct btree *child;
-                       BKEY_PADDED(k) tmp;
+void bch2_btree_and_journal_iter_advance(struct btree_and_journal_iter *iter)
+{
+       if (bpos_eq(iter->pos, SPOS_MAX))
+               iter->at_end = true;
+       else
+               iter->pos = bpos_successor(iter->pos);
+}
 
-                       bkey_reassemble(&tmp.k, k);
-                       k = bkey_i_to_s_c(&tmp.k);
+struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *iter)
+{
+       struct bkey_s_c btree_k, journal_k, ret;
+again:
+       if (iter->at_end)
+               return bkey_s_c_null;
 
-                       bch2_btree_and_journal_iter_advance(&iter);
+       while ((btree_k = bch2_journal_iter_peek_btree(iter)).k &&
+              bpos_lt(btree_k.k->p, iter->pos))
+               bch2_journal_iter_advance_btree(iter);
 
-                       if (b->c.level > 0) {
-                               child = bch2_btree_node_get_noiter(c, &tmp.k,
-                                                       b->c.btree_id, b->c.level - 1);
-                               ret = PTR_ERR_OR_ZERO(child);
-                               if (ret)
-                                       break;
+       while ((journal_k = bch2_journal_iter_peek(&iter->journal)).k &&
+              bpos_lt(journal_k.k->p, iter->pos))
+               bch2_journal_iter_advance(&iter->journal);
 
-                               ret   = (node_fn ? node_fn(c, b) : 0) ?:
-                                       bch2_btree_and_journal_walk_recurse(c, child,
-                                               journal_keys, btree_id, node_fn, key_fn);
-                               six_unlock_read(&child->c.lock);
+       ret = journal_k.k &&
+               (!btree_k.k || bpos_le(journal_k.k->p, btree_k.k->p))
+               ? journal_k
+               : btree_k;
 
-                               if (ret)
-                                       break;
-                       }
-               } else {
-                       bch2_btree_and_journal_iter_advance(&iter);
+       if (ret.k && iter->b && bpos_gt(ret.k->p, iter->b->data->max_key))
+               ret = bkey_s_c_null;
+
+       if (ret.k) {
+               iter->pos = ret.k->p;
+               if (bkey_deleted(ret.k)) {
+                       bch2_btree_and_journal_iter_advance(iter);
+                       goto again;
                }
+       } else {
+               iter->pos = SPOS_MAX;
+               iter->at_end = true;
        }
 
        return ret;
 }
 
-int bch2_btree_and_journal_walk(struct bch_fs *c, struct journal_keys *journal_keys,
-                               enum btree_id btree_id,
-                               btree_walk_node_fn node_fn,
-                               btree_walk_key_fn key_fn)
+void bch2_btree_and_journal_iter_exit(struct btree_and_journal_iter *iter)
 {
-       struct btree *b = c->btree_roots[btree_id].b;
-       int ret = 0;
+       bch2_journal_iter_exit(&iter->journal);
+}
 
-       if (btree_node_fake(b))
-               return 0;
+void __bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter *iter,
+                                                 struct bch_fs *c,
+                                                 struct btree *b,
+                                                 struct btree_node_iter node_iter,
+                                                 struct bpos pos)
+{
+       memset(iter, 0, sizeof(*iter));
 
-       six_lock_read(&b->c.lock, NULL, NULL);
-       ret   = (node_fn ? node_fn(c, b) : 0) ?:
-               bch2_btree_and_journal_walk_recurse(c, b, journal_keys, btree_id,
-                                                   node_fn, key_fn) ?:
-               key_fn(c, btree_id, b->c.level + 1, bkey_i_to_s_c(&b->key));
-       six_unlock_read(&b->c.lock);
+       iter->b = b;
+       iter->node_iter = node_iter;
+       bch2_journal_iter_init(c, &iter->journal, b->c.btree_id, b->c.level, pos);
+       INIT_LIST_HEAD(&iter->journal.list);
+       iter->pos = b->data->min_key;
+       iter->at_end = false;
+}
 
-       return ret;
+/*
+ * this version is used by btree_gc before filesystem has gone RW and
+ * multithreaded, so uses the journal_iters list:
+ */
+void bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter *iter,
+                                               struct bch_fs *c,
+                                               struct btree *b)
+{
+       struct btree_node_iter node_iter;
+
+       bch2_btree_node_iter_init_from_start(&node_iter, b);
+       __bch2_btree_and_journal_iter_init_node_iter(iter, c, b, node_iter, b->data->min_key);
+       list_add(&iter->journal.list, &c->journal_iters);
 }
 
 /* sort and dedup all keys in the journal: */
 
-void bch2_journal_entries_free(struct list_head *list)
+void bch2_journal_entries_free(struct bch_fs *c)
 {
-
-       while (!list_empty(list)) {
-               struct journal_replay *i =
-                       list_first_entry(list, struct journal_replay, list);
-               list_del(&i->list);
-               kvpfree(i, offsetof(struct journal_replay, j) +
-                       vstruct_bytes(&i->j));
-       }
+       struct journal_replay **i;
+       struct genradix_iter iter;
+
+       genradix_for_each(&c->journal_entries, iter, i)
+               if (*i)
+                       kvpfree(*i, offsetof(struct journal_replay, j) +
+                               vstruct_bytes(&(*i)->j));
+       genradix_free(&c->journal_entries);
 }
 
 /*
@@ -285,391 +455,236 @@ static int journal_sort_key_cmp(const void *_l, const void *_r)
        const struct journal_key *l = _l;
        const struct journal_key *r = _r;
 
-       return  cmp_int(l->btree_id,    r->btree_id) ?:
-               cmp_int(l->level,       r->level) ?:
-               bkey_cmp(l->k->k.p, r->k->k.p) ?:
+       return  journal_key_cmp(l, r) ?:
                cmp_int(l->journal_seq, r->journal_seq) ?:
                cmp_int(l->journal_offset, r->journal_offset);
 }
 
 void bch2_journal_keys_free(struct journal_keys *keys)
 {
+       struct journal_key *i;
+
+       move_gap(keys->d, keys->nr, keys->size, keys->gap, keys->nr);
+       keys->gap = keys->nr;
+
+       for (i = keys->d; i < keys->d + keys->nr; i++)
+               if (i->allocated)
+                       kfree(i->k);
+
        kvfree(keys->d);
        keys->d = NULL;
-       keys->nr = 0;
+       keys->nr = keys->gap = keys->size = 0;
 }
 
-static struct journal_keys journal_keys_sort(struct list_head *journal_entries)
+static void __journal_keys_sort(struct journal_keys *keys)
 {
-       struct journal_replay *p;
-       struct jset_entry *entry;
-       struct bkey_i *k, *_n;
-       struct journal_keys keys = { NULL };
        struct journal_key *src, *dst;
-       size_t nr_keys = 0;
-
-       if (list_empty(journal_entries))
-               return keys;
-
-       keys.journal_seq_base =
-               le64_to_cpu(list_last_entry(journal_entries,
-                               struct journal_replay, list)->j.last_seq);
-
-       list_for_each_entry(p, journal_entries, list) {
-               if (le64_to_cpu(p->j.seq) < keys.journal_seq_base)
-                       continue;
-
-               for_each_jset_key(k, _n, entry, &p->j)
-                       nr_keys++;
-       }
-
-
-       keys.d = kvmalloc(sizeof(keys.d[0]) * nr_keys, GFP_KERNEL);
-       if (!keys.d)
-               goto err;
-
-       list_for_each_entry(p, journal_entries, list) {
-               if (le64_to_cpu(p->j.seq) < keys.journal_seq_base)
-                       continue;
-
-               for_each_jset_key(k, _n, entry, &p->j)
-                       keys.d[keys.nr++] = (struct journal_key) {
-                               .btree_id       = entry->btree_id,
-                               .level          = entry->level,
-                               .k              = k,
-                               .journal_seq    = le64_to_cpu(p->j.seq) -
-                                       keys.journal_seq_base,
-                               .journal_offset = k->_data - p->j._data,
-                       };
-       }
 
-       sort(keys.d, keys.nr, sizeof(keys.d[0]), journal_sort_key_cmp, NULL);
+       sort(keys->d, keys->nr, sizeof(keys->d[0]), journal_sort_key_cmp, NULL);
 
-       src = dst = keys.d;
-       while (src < keys.d + keys.nr) {
-               while (src + 1 < keys.d + keys.nr &&
+       src = dst = keys->d;
+       while (src < keys->d + keys->nr) {
+               while (src + 1 < keys->d + keys->nr &&
                       src[0].btree_id  == src[1].btree_id &&
                       src[0].level     == src[1].level &&
-                      !bkey_cmp(src[0].k->k.p, src[1].k->k.p))
+                      bpos_eq(src[0].k->k.p, src[1].k->k.p))
                        src++;
 
                *dst++ = *src++;
        }
 
-       keys.nr = dst - keys.d;
-err:
-       return keys;
+       keys->nr = dst - keys->d;
 }
 
-/* journal replay: */
-
-static void replay_now_at(struct journal *j, u64 seq)
+static int journal_keys_sort(struct bch_fs *c)
 {
-       BUG_ON(seq < j->replay_journal_seq);
-       BUG_ON(seq > j->replay_journal_seq_end);
+       struct genradix_iter iter;
+       struct journal_replay *i, **_i;
+       struct jset_entry *entry;
+       struct bkey_i *k;
+       struct journal_keys *keys = &c->journal_keys;
+       size_t nr_keys = 0, nr_read = 0;
 
-       while (j->replay_journal_seq < seq)
-               bch2_journal_pin_put(j, j->replay_journal_seq++);
-}
+       genradix_for_each(&c->journal_entries, iter, _i) {
+               i = *_i;
 
-static int bch2_extent_replay_key(struct bch_fs *c, enum btree_id btree_id,
-                                 struct bkey_i *k)
-{
-       struct btree_trans trans;
-       struct btree_iter *iter, *split_iter;
-       /*
-        * We might cause compressed extents to be split, so we need to pass in
-        * a disk_reservation:
-        */
-       struct disk_reservation disk_res =
-               bch2_disk_reservation_init(c, 0);
-       struct bkey_i *split;
-       struct bpos atomic_end;
-       /*
-        * Some extents aren't equivalent - w.r.t. what the triggers do
-        * - if they're split:
-        */
-       bool remark_if_split = bch2_bkey_sectors_compressed(bkey_i_to_s_c(k)) ||
-               k->k.type == KEY_TYPE_reflink_p;
-       bool remark = false;
-       int ret;
+               if (!i || i->ignore)
+                       continue;
 
-       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
-retry:
-       bch2_trans_begin(&trans);
+               for_each_jset_key(k, entry, &i->j)
+                       nr_keys++;
+       }
 
-       iter = bch2_trans_get_iter(&trans, btree_id,
-                                  bkey_start_pos(&k->k),
-                                  BTREE_ITER_INTENT);
+       if (!nr_keys)
+               return 0;
 
-       do {
-               ret = bch2_btree_iter_traverse(iter);
-               if (ret)
-                       goto err;
+       keys->size = roundup_pow_of_two(nr_keys);
 
-               atomic_end = bpos_min(k->k.p, iter->l[0].b->key.k.p);
+       keys->d = kvmalloc_array(keys->size, sizeof(keys->d[0]), GFP_KERNEL);
+       if (!keys->d) {
+               bch_err(c, "Failed to allocate buffer for sorted journal keys (%zu keys); trying slowpath",
+                       nr_keys);
 
-               split = bch2_trans_kmalloc(&trans, bkey_bytes(&k->k));
-               ret = PTR_ERR_OR_ZERO(split);
-               if (ret)
-                       goto err;
+               do {
+                       keys->size >>= 1;
+                       keys->d = kvmalloc_array(keys->size, sizeof(keys->d[0]), GFP_KERNEL);
+               } while (!keys->d && keys->size > nr_keys / 8);
+
+               if (!keys->d) {
+                       bch_err(c, "Failed to allocate %zu size buffer for sorted journal keys; exiting",
+                               keys->size);
+                       return -BCH_ERR_ENOMEM_journal_keys_sort;
+               }
+       }
 
-               if (!remark &&
-                   remark_if_split &&
-                   bkey_cmp(atomic_end, k->k.p) < 0) {
-                       ret = bch2_disk_reservation_add(c, &disk_res,
-                                       k->k.size *
-                                       bch2_bkey_nr_ptrs_allocated(bkey_i_to_s_c(k)),
-                                       BCH_DISK_RESERVATION_NOFAIL);
-                       BUG_ON(ret);
+       genradix_for_each(&c->journal_entries, iter, _i) {
+               i = *_i;
 
-                       remark = true;
-               }
+               if (!i || i->ignore)
+                       continue;
 
-               bkey_copy(split, k);
-               bch2_cut_front(iter->pos, split);
-               bch2_cut_back(atomic_end, split);
+               cond_resched();
 
-               split_iter = bch2_trans_copy_iter(&trans, iter);
-               ret = PTR_ERR_OR_ZERO(split_iter);
-               if (ret)
-                       goto err;
+               for_each_jset_key(k, entry, &i->j) {
+                       if (keys->nr == keys->size) {
+                               __journal_keys_sort(keys);
 
-               /*
-                * It's important that we don't go through the
-                * extent_handle_overwrites() and extent_update_to_keys() path
-                * here: journal replay is supposed to treat extents like
-                * regular keys
-                */
-               __bch2_btree_iter_set_pos(split_iter, split->k.p, false);
-               bch2_trans_update(&trans, split_iter, split,
-                                 BTREE_TRIGGER_NORUN);
+                               if (keys->nr > keys->size * 7 / 8) {
+                                       bch_err(c, "Too many journal keys for slowpath; have %zu compacted, buf size %zu, processed %zu/%zu",
+                                               keys->nr, keys->size, nr_read, nr_keys);
+                                       return -BCH_ERR_ENOMEM_journal_keys_sort;
+                               }
+                       }
 
-               bch2_btree_iter_set_pos(iter, split->k.p);
+                       keys->d[keys->nr++] = (struct journal_key) {
+                               .btree_id       = entry->btree_id,
+                               .level          = entry->level,
+                               .k              = k,
+                               .journal_seq    = le64_to_cpu(i->j.seq),
+                               .journal_offset = k->_data - i->j._data,
+                       };
 
-               if (remark) {
-                       ret = bch2_trans_mark_key(&trans, bkey_i_to_s_c(split),
-                                                 0, split->k.size,
-                                                 BTREE_TRIGGER_INSERT);
-                       if (ret)
-                               goto err;
+                       nr_read++;
                }
-       } while (bkey_cmp(iter->pos, k->k.p) < 0);
-
-       if (remark) {
-               ret = bch2_trans_mark_key(&trans, bkey_i_to_s_c(k),
-                                         0, -((s64) k->k.size),
-                                         BTREE_TRIGGER_OVERWRITE);
-               if (ret)
-                       goto err;
        }
 
-       ret = bch2_trans_commit(&trans, &disk_res, NULL,
-                               BTREE_INSERT_NOFAIL|
-                               BTREE_INSERT_LAZY_RW|
-                               BTREE_INSERT_JOURNAL_REPLAY);
-err:
-       if (ret == -EINTR)
-               goto retry;
-
-       bch2_disk_reservation_put(c, &disk_res);
+       __journal_keys_sort(keys);
+       keys->gap = keys->nr;
 
-       return bch2_trans_exit(&trans) ?: ret;
+       bch_verbose(c, "Journal keys: %zu read, %zu after sorting and compacting", nr_keys, keys->nr);
+       return 0;
 }
 
-static int __bch2_journal_replay_key(struct btree_trans *trans,
-                                    enum btree_id id, unsigned level,
-                                    struct bkey_i *k)
-{
-       struct btree_iter *iter;
-       int ret;
+/* journal replay: */
 
-       iter = bch2_trans_get_node_iter(trans, id, k->k.p,
-                                       BTREE_MAX_DEPTH, level,
-                                       BTREE_ITER_INTENT);
-       if (IS_ERR(iter))
-               return PTR_ERR(iter);
+static void replay_now_at(struct journal *j, u64 seq)
+{
+       BUG_ON(seq < j->replay_journal_seq);
 
-       /*
-        * iter->flags & BTREE_ITER_IS_EXTENTS triggers the update path to run
-        * extent_handle_overwrites() and extent_update_to_keys() - but we don't
-        * want that here, journal replay is supposed to treat extents like
-        * regular keys:
-        */
-       __bch2_btree_iter_set_pos(iter, k->k.p, false);
+       seq = min(seq, j->replay_journal_seq_end);
 
-       ret   = bch2_btree_iter_traverse(iter) ?:
-               bch2_trans_update(trans, iter, k, BTREE_TRIGGER_NORUN);
-       bch2_trans_iter_put(trans, iter);
-       return ret;
-}
-
-static int bch2_journal_replay_key(struct bch_fs *c, enum btree_id id,
-                                  unsigned level, struct bkey_i *k)
-{
-       return bch2_trans_do(c, NULL, NULL,
-                            BTREE_INSERT_NOFAIL|
-                            BTREE_INSERT_LAZY_RW|
-                            BTREE_INSERT_JOURNAL_REPLAY,
-                            __bch2_journal_replay_key(&trans, id, level, k));
+       while (j->replay_journal_seq < seq)
+               bch2_journal_pin_put(j, j->replay_journal_seq++);
 }
 
-static int __bch2_alloc_replay_key(struct btree_trans *trans, struct bkey_i *k)
+static int bch2_journal_replay_key(struct btree_trans *trans,
+                                  struct journal_key *k)
 {
-       struct btree_iter *iter;
+       struct btree_iter iter;
+       unsigned iter_flags =
+               BTREE_ITER_INTENT|
+               BTREE_ITER_NOT_EXTENTS;
        int ret;
 
-       iter = bch2_trans_get_iter(trans, BTREE_ID_ALLOC, k->k.p,
-                                  BTREE_ITER_CACHED|
-                                  BTREE_ITER_CACHED_NOFILL|
-                                  BTREE_ITER_INTENT);
-       ret =   PTR_ERR_OR_ZERO(iter) ?:
-               bch2_trans_update(trans, iter, k, BTREE_TRIGGER_NORUN);
-       bch2_trans_iter_put(trans, iter);
-       return ret;
-}
+       if (!k->level && k->btree_id == BTREE_ID_alloc)
+               iter_flags |= BTREE_ITER_CACHED;
 
-static int bch2_alloc_replay_key(struct bch_fs *c, struct bkey_i *k)
-{
-       return bch2_trans_do(c, NULL, NULL,
-                            BTREE_INSERT_NOFAIL|
-                            BTREE_INSERT_USE_RESERVE|
-                            BTREE_INSERT_LAZY_RW|
-                            BTREE_INSERT_JOURNAL_REPLAY,
-                       __bch2_alloc_replay_key(&trans, k));
+       bch2_trans_node_iter_init(trans, &iter, k->btree_id, k->k->k.p,
+                                 BTREE_MAX_DEPTH, k->level,
+                                 iter_flags);
+       ret = bch2_btree_iter_traverse(&iter);
+       if (ret)
+               goto out;
+
+       /* Must be checked with btree locked: */
+       if (k->overwritten)
+               goto out;
+
+       ret = bch2_trans_update(trans, &iter, k->k, BTREE_TRIGGER_NORUN);
+out:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
 }
 
 static int journal_sort_seq_cmp(const void *_l, const void *_r)
 {
-       const struct journal_key *l = _l;
-       const struct journal_key *r = _r;
+       const struct journal_key *l = *((const struct journal_key **)_l);
+       const struct journal_key *r = *((const struct journal_key **)_r);
 
-       return  cmp_int(r->level,       l->level) ?:
-               cmp_int(l->journal_seq, r->journal_seq) ?:
-               cmp_int(l->btree_id,    r->btree_id) ?:
-               bkey_cmp(l->k->k.p,     r->k->k.p);
+       return cmp_int(l->journal_seq, r->journal_seq);
 }
 
-static int bch2_journal_replay(struct bch_fs *c,
-                              struct journal_keys keys)
+static int bch2_journal_replay(struct bch_fs *c, u64 start_seq, u64 end_seq)
 {
+       struct journal_keys *keys = &c->journal_keys;
+       struct journal_key **keys_sorted, *k;
        struct journal *j = &c->journal;
-       struct journal_key *i;
-       u64 seq;
+       size_t i;
        int ret;
 
-       sort(keys.d, keys.nr, sizeof(keys.d[0]), journal_sort_seq_cmp, NULL);
-
-       if (keys.nr)
-               replay_now_at(j, keys.journal_seq_base);
-
-       seq = j->replay_journal_seq;
-
-       /*
-        * First replay updates to the alloc btree - these will only update the
-        * btree key cache:
-        */
-       for_each_journal_key(keys, i) {
-               cond_resched();
-
-               if (!i->level && i->btree_id == BTREE_ID_ALLOC) {
-                       j->replay_journal_seq = keys.journal_seq_base + i->journal_seq;
-                       ret = bch2_alloc_replay_key(c, i->k);
-                       if (ret)
-                               goto err;
-               }
-       }
-
-       /*
-        * Next replay updates to interior btree nodes:
-        */
-       for_each_journal_key(keys, i) {
-               cond_resched();
-
-               if (i->level) {
-                       j->replay_journal_seq = keys.journal_seq_base + i->journal_seq;
-                       ret = bch2_journal_replay_key(c, i->btree_id, i->level, i->k);
-                       if (ret)
-                               goto err;
-               }
-       }
-
-       /*
-        * Now that the btree is in a consistent state, we can start journal
-        * reclaim (which will be flushing entries from the btree key cache back
-        * to the btree:
-        */
-       set_bit(BCH_FS_BTREE_INTERIOR_REPLAY_DONE, &c->flags);
-       set_bit(JOURNAL_RECLAIM_STARTED, &j->flags);
-
-       j->replay_journal_seq = seq;
+       move_gap(keys->d, keys->nr, keys->size, keys->gap, keys->nr);
+       keys->gap = keys->nr;
 
-       /*
-        * Now replay leaf node updates:
-        */
-       for_each_journal_key(keys, i) {
-               cond_resched();
+       keys_sorted = kvmalloc_array(sizeof(*keys_sorted), keys->nr, GFP_KERNEL);
+       if (!keys_sorted)
+               return -BCH_ERR_ENOMEM_journal_replay;
 
-               if (i->level || i->btree_id == BTREE_ID_ALLOC)
-                       continue;
+       for (i = 0; i < keys->nr; i++)
+               keys_sorted[i] = &keys->d[i];
 
-               replay_now_at(j, keys.journal_seq_base + i->journal_seq);
+       sort(keys_sorted, keys->nr,
+            sizeof(keys_sorted[0]),
+            journal_sort_seq_cmp, NULL);
 
-               ret = i->k->k.size
-                       ? bch2_extent_replay_key(c, i->btree_id, i->k)
-                       : bch2_journal_replay_key(c, i->btree_id, i->level, i->k);
+       if (keys->nr) {
+               ret = bch2_journal_log_msg(c, "Starting journal replay (%zu keys in entries %llu-%llu)",
+                                          keys->nr, start_seq, end_seq);
                if (ret)
                        goto err;
        }
 
-       replay_now_at(j, j->replay_journal_seq_end);
-       j->replay_journal_seq = 0;
-
-       bch2_journal_set_replay_done(j);
-       bch2_journal_flush_all_pins(j);
-       return bch2_journal_error(j);
-err:
-       bch_err(c, "journal replay: error %d while replaying key", ret);
-       return ret;
-}
-
-static bool journal_empty(struct list_head *journal)
-{
-       return list_empty(journal) ||
-               journal_entry_empty(&list_last_entry(journal,
-                                       struct journal_replay, list)->j);
-}
-
-static int
-verify_journal_entries_not_blacklisted_or_missing(struct bch_fs *c,
-                                                 struct list_head *journal)
-{
-       struct journal_replay *i =
-               list_last_entry(journal, struct journal_replay, list);
-       u64 start_seq   = le64_to_cpu(i->j.last_seq);
-       u64 end_seq     = le64_to_cpu(i->j.seq);
-       u64 seq         = start_seq;
-       int ret = 0;
+       for (i = 0; i < keys->nr; i++) {
+               k = keys_sorted[i];
 
-       list_for_each_entry(i, journal, list) {
-               if (le64_to_cpu(i->j.seq) < start_seq)
-                       continue;
+               cond_resched();
 
-               fsck_err_on(seq != le64_to_cpu(i->j.seq), c,
-                       "journal entries %llu-%llu missing! (replaying %llu-%llu)",
-                       seq, le64_to_cpu(i->j.seq) - 1,
-                       start_seq, end_seq);
+               replay_now_at(j, k->journal_seq);
+
+               ret = bch2_trans_do(c, NULL, NULL,
+                                   BTREE_INSERT_LAZY_RW|
+                                   BTREE_INSERT_NOFAIL|
+                                   (!k->allocated
+                                    ? BTREE_INSERT_JOURNAL_REPLAY|JOURNAL_WATERMARK_reserved
+                                    : 0),
+                            bch2_journal_replay_key(&trans, k));
+               if (ret) {
+                       bch_err(c, "journal replay: error while replaying key at btree %s level %u: %s",
+                               bch2_btree_ids[k->btree_id], k->level, bch2_err_str(ret));
+                       goto err;
+               }
+       }
 
-               seq = le64_to_cpu(i->j.seq);
+       replay_now_at(j, j->replay_journal_seq_end);
+       j->replay_journal_seq = 0;
 
-               fsck_err_on(bch2_journal_seq_is_blacklisted(c, seq, false), c,
-                           "found blacklisted journal entry %llu", seq);
+       bch2_journal_set_replay_done(j);
+       bch2_journal_flush_all_pins(j);
+       ret = bch2_journal_error(j);
 
-               do {
-                       seq++;
-               } while (bch2_journal_seq_is_blacklisted(c, seq, false));
-       }
-fsck_err:
+       if (keys->nr && !ret)
+               bch2_journal_log_msg(c, "journal replay finished");
+err:
+       kvfree(keys_sorted);
        return ret;
 }
 
@@ -707,15 +722,15 @@ static int journal_replay_entry_early(struct bch_fs *c,
                        container_of(entry, struct jset_entry_usage, entry);
 
                switch (entry->btree_id) {
-               case FS_USAGE_RESERVED:
+               case BCH_FS_USAGE_reserved:
                        if (entry->level < BCH_REPLICAS_MAX)
                                c->usage_base->persistent_reserved[entry->level] =
                                        le64_to_cpu(u->v);
                        break;
-               case FS_USAGE_INODES:
+               case BCH_FS_USAGE_inodes:
                        c->usage_base->nr_inodes = le64_to_cpu(u->v);
                        break;
-               case FS_USAGE_KEY_VERSION:
+               case BCH_FS_USAGE_key_version:
                        atomic64_set(&c->key_version,
                                     le64_to_cpu(u->v));
                        break;
@@ -726,10 +741,27 @@ static int journal_replay_entry_early(struct bch_fs *c,
        case BCH_JSET_ENTRY_data_usage: {
                struct jset_entry_data_usage *u =
                        container_of(entry, struct jset_entry_data_usage, entry);
+
                ret = bch2_replicas_set_usage(c, &u->r,
                                              le64_to_cpu(u->v));
                break;
        }
+       case BCH_JSET_ENTRY_dev_usage: {
+               struct jset_entry_dev_usage *u =
+                       container_of(entry, struct jset_entry_dev_usage, entry);
+               struct bch_dev *ca = bch_dev_bkey_exists(c, le32_to_cpu(u->dev));
+               unsigned i, nr_types = jset_entry_dev_usage_nr_types(u);
+
+               ca->usage_base->buckets_ec              = le64_to_cpu(u->buckets_ec);
+
+               for (i = 0; i < min_t(unsigned, nr_types, BCH_DATA_NR); i++) {
+                       ca->usage_base->d[i].buckets    = le64_to_cpu(u->d[i].buckets);
+                       ca->usage_base->d[i].sectors    = le64_to_cpu(u->d[i].sectors);
+                       ca->usage_base->d[i].fragmented = le64_to_cpu(u->d[i].fragmented);
+               }
+
+               break;
+       }
        case BCH_JSET_ENTRY_blacklist: {
                struct jset_entry_blacklist *bl_entry =
                        container_of(entry, struct jset_entry_blacklist, entry);
@@ -748,22 +780,24 @@ static int journal_replay_entry_early(struct bch_fs *c,
                                le64_to_cpu(bl_entry->end) + 1);
                break;
        }
+       case BCH_JSET_ENTRY_clock: {
+               struct jset_entry_clock *clock =
+                       container_of(entry, struct jset_entry_clock, entry);
+
+               atomic64_set(&c->io_clock[clock->rw].now, le64_to_cpu(clock->time));
+       }
        }
 
        return ret;
 }
 
 static int journal_replay_early(struct bch_fs *c,
-                               struct bch_sb_field_clean *clean,
-                               struct list_head *journal)
+                               struct bch_sb_field_clean *clean)
 {
        struct jset_entry *entry;
        int ret;
 
        if (clean) {
-               c->bucket_clock[READ].hand = le16_to_cpu(clean->read_clock);
-               c->bucket_clock[WRITE].hand = le16_to_cpu(clean->write_clock);
-
                for (entry = clean->start;
                     entry != vstruct_end(&clean->field);
                     entry = vstruct_next(entry)) {
@@ -772,18 +806,21 @@ static int journal_replay_early(struct bch_fs *c,
                                return ret;
                }
        } else {
-               struct journal_replay *i =
-                       list_last_entry(journal, struct journal_replay, list);
+               struct genradix_iter iter;
+               struct journal_replay *i, **_i;
+
+               genradix_for_each(&c->journal_entries, iter, _i) {
+                       i = *_i;
 
-               c->bucket_clock[READ].hand = le16_to_cpu(i->j.read_clock);
-               c->bucket_clock[WRITE].hand = le16_to_cpu(i->j.write_clock);
+                       if (!i || i->ignore)
+                               continue;
 
-               list_for_each_entry(i, journal, list)
                        vstruct_for_each(&i->j, entry) {
                                ret = journal_replay_entry_early(c, entry);
                                if (ret)
                                        return ret;
                        }
+               }
        }
 
        bch2_fs_usage_initialize(c);
@@ -830,11 +867,10 @@ static int verify_superblock_clean(struct bch_fs *c,
 {
        unsigned i;
        struct bch_sb_field_clean *clean = *cleanp;
+       struct printbuf buf1 = PRINTBUF;
+       struct printbuf buf2 = PRINTBUF;
        int ret = 0;
 
-       if (!c->sb.clean || !j)
-               return 0;
-
        if (mustfix_fsck_err_on(j->seq != clean->journal_seq, c,
                        "superblock journal seq (%llu) doesn't match journal (%llu) after clean shutdown",
                        le64_to_cpu(clean->journal_seq),
@@ -844,15 +880,7 @@ static int verify_superblock_clean(struct bch_fs *c,
                return 0;
        }
 
-       mustfix_fsck_err_on(j->read_clock != clean->read_clock, c,
-                       "superblock read clock %u doesn't match journal %u after clean shutdown",
-                       clean->read_clock, j->read_clock);
-       mustfix_fsck_err_on(j->write_clock != clean->write_clock, c,
-                       "superblock write clock %u doesn't match journal %u after clean shutdown",
-                       clean->write_clock, j->write_clock);
-
        for (i = 0; i < BTREE_ID_NR; i++) {
-               char buf1[200], buf2[200];
                struct bkey_i *k1, *k2;
                unsigned l1 = 0, l2 = 0;
 
@@ -862,19 +890,34 @@ static int verify_superblock_clean(struct bch_fs *c,
                if (!k1 && !k2)
                        continue;
 
+               printbuf_reset(&buf1);
+               printbuf_reset(&buf2);
+
+               if (k1)
+                       bch2_bkey_val_to_text(&buf1, c, bkey_i_to_s_c(k1));
+               else
+                       prt_printf(&buf1, "(none)");
+
+               if (k2)
+                       bch2_bkey_val_to_text(&buf2, c, bkey_i_to_s_c(k2));
+               else
+                       prt_printf(&buf2, "(none)");
+
                mustfix_fsck_err_on(!k1 || !k2 ||
                                    IS_ERR(k1) ||
                                    IS_ERR(k2) ||
                                    k1->k.u64s != k2->k.u64s ||
-                                   memcmp(k1, k2, bkey_bytes(k1)) ||
+                                   memcmp(k1, k2, bkey_bytes(&k1->k)) ||
                                    l1 != l2, c,
                        "superblock btree root %u doesn't match journal after clean shutdown\n"
                        "sb:      l=%u %s\n"
                        "journal: l=%u %s\n", i,
-                       l1, (bch2_bkey_val_to_text(&PBUF(buf1), c, bkey_i_to_s_c(k1)), buf1),
-                       l2, (bch2_bkey_val_to_text(&PBUF(buf2), c, bkey_i_to_s_c(k2)), buf2));
+                       l1, buf1.buf,
+                       l2, buf2.buf);
        }
 fsck_err:
+       printbuf_exit(&buf2);
+       printbuf_exit(&buf1);
        return ret;
 }
 
@@ -898,12 +941,14 @@ static struct bch_sb_field_clean *read_superblock_clean(struct bch_fs *c)
                        GFP_KERNEL);
        if (!clean) {
                mutex_unlock(&c->sb_lock);
-               return ERR_PTR(-ENOMEM);
+               return ERR_PTR(-BCH_ERR_ENOMEM_read_superblock_clean);
        }
 
-       if (le16_to_cpu(c->disk_sb.sb->version) <
-           bcachefs_metadata_version_bkey_renumber)
-               bch2_sb_clean_renumber(clean, READ);
+       ret = bch2_sb_clean_validate_late(c, clean, READ);
+       if (ret) {
+               mutex_unlock(&c->sb_lock);
+               return ERR_PTR(ret);
+       }
 
        mutex_unlock(&c->sb_lock);
 
@@ -913,6 +958,20 @@ fsck_err:
        return ERR_PTR(ret);
 }
 
+static bool btree_id_is_alloc(enum btree_id id)
+{
+       switch (id) {
+       case BTREE_ID_alloc:
+       case BTREE_ID_backpointers:
+       case BTREE_ID_need_discard:
+       case BTREE_ID_freespace:
+       case BTREE_ID_bucket_gens:
+               return true;
+       default:
+               return false;
+       }
+}
+
 static int read_btree_roots(struct bch_fs *c)
 {
        unsigned i;
@@ -924,47 +983,120 @@ static int read_btree_roots(struct bch_fs *c)
                if (!r->alive)
                        continue;
 
-               if (i == BTREE_ID_ALLOC &&
+               if (btree_id_is_alloc(i) &&
                    c->opts.reconstruct_alloc) {
-                       c->sb.compat &= ~(1ULL << BCH_COMPAT_FEAT_ALLOC_INFO);
+                       c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                        continue;
                }
 
-
                if (r->error) {
-                       __fsck_err(c, i == BTREE_ID_ALLOC
+                       __fsck_err(c, btree_id_is_alloc(i)
                                   ? FSCK_CAN_IGNORE : 0,
                                   "invalid btree root %s",
                                   bch2_btree_ids[i]);
-                       if (i == BTREE_ID_ALLOC)
-                               c->sb.compat &= ~(1ULL << BCH_COMPAT_FEAT_ALLOC_INFO);
+                       if (i == BTREE_ID_alloc)
+                               c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                }
 
                ret = bch2_btree_root_read(c, i, &r->key, r->level);
                if (ret) {
-                       __fsck_err(c, i == BTREE_ID_ALLOC
+                       __fsck_err(c,
+                                  btree_id_is_alloc(i)
                                   ? FSCK_CAN_IGNORE : 0,
                                   "error reading btree root %s",
                                   bch2_btree_ids[i]);
-                       if (i == BTREE_ID_ALLOC)
-                               c->sb.compat &= ~(1ULL << BCH_COMPAT_FEAT_ALLOC_INFO);
+                       if (btree_id_is_alloc(i))
+                               c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                }
        }
 
-       for (i = 0; i < BTREE_ID_NR; i++)
-               if (!c->btree_roots[i].b)
+       for (i = 0; i < BTREE_ID_NR; i++) {
+               struct btree_root *r = &c->btree_roots[i];
+
+               if (!r->b) {
+                       r->alive = false;
+                       r->level = 0;
                        bch2_btree_root_alloc(c, i);
+               }
+       }
 fsck_err:
        return ret;
 }
 
+static int bch2_fs_initialize_subvolumes(struct bch_fs *c)
+{
+       struct bkey_i_snapshot  root_snapshot;
+       struct bkey_i_subvolume root_volume;
+       int ret;
+
+       bkey_snapshot_init(&root_snapshot.k_i);
+       root_snapshot.k.p.offset = U32_MAX;
+       root_snapshot.v.flags   = 0;
+       root_snapshot.v.parent  = 0;
+       root_snapshot.v.subvol  = BCACHEFS_ROOT_SUBVOL;
+       root_snapshot.v.pad     = 0;
+       SET_BCH_SNAPSHOT_SUBVOL(&root_snapshot.v, true);
+
+       ret = bch2_btree_insert(c, BTREE_ID_snapshots,
+                               &root_snapshot.k_i,
+                               NULL, NULL, 0);
+       if (ret)
+               return ret;
+
+       bkey_subvolume_init(&root_volume.k_i);
+       root_volume.k.p.offset = BCACHEFS_ROOT_SUBVOL;
+       root_volume.v.flags     = 0;
+       root_volume.v.snapshot  = cpu_to_le32(U32_MAX);
+       root_volume.v.inode     = cpu_to_le64(BCACHEFS_ROOT_INO);
+
+       ret = bch2_btree_insert(c, BTREE_ID_subvolumes,
+                               &root_volume.k_i,
+                               NULL, NULL, 0);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+static int bch2_fs_upgrade_for_subvolumes(struct btree_trans *trans)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bch_inode_unpacked inode;
+       int ret;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
+                            SPOS(0, BCACHEFS_ROOT_INO, U32_MAX), 0);
+       k = bch2_btree_iter_peek_slot(&iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (!bkey_is_inode(k.k)) {
+               bch_err(trans->c, "root inode not found");
+               ret = -ENOENT;
+               goto err;
+       }
+
+       ret = bch2_inode_unpack(k, &inode);
+       BUG_ON(ret);
+
+       inode.bi_subvol = BCACHEFS_ROOT_SUBVOL;
+
+       ret = bch2_inode_write(trans, &iter, &inode);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
 int bch2_fs_recovery(struct bch_fs *c)
 {
        const char *err = "cannot allocate memory";
        struct bch_sb_field_clean *clean = NULL;
-       u64 journal_seq;
-       bool write_sb = false, need_write_alloc = false;
-       int ret;
+       struct jset *last_journal_entry = NULL;
+       u64 last_seq, blacklist_seq, journal_seq;
+       bool write_sb = false;
+       int ret = 0;
 
        if (c->sb.clean)
                clean = read_superblock_clean(c);
@@ -975,199 +1107,318 @@ int bch2_fs_recovery(struct bch_fs *c)
        if (c->sb.clean)
                bch_info(c, "recovering from clean shutdown, journal seq %llu",
                         le64_to_cpu(clean->journal_seq));
+       else
+               bch_info(c, "recovering from unclean shutdown");
+
+       if (!(c->sb.features & (1ULL << BCH_FEATURE_new_extent_overwrite))) {
+               bch_err(c, "feature new_extent_overwrite not set, filesystem no longer supported");
+               ret = -EINVAL;
+               goto err;
+       }
+
+       if (!c->sb.clean &&
+           !(c->sb.features & (1ULL << BCH_FEATURE_extents_above_btree_updates))) {
+               bch_err(c, "filesystem needs recovery from older version; run fsck from older bcachefs-tools to fix");
+               ret = -EINVAL;
+               goto err;
+       }
+
+       if (!(c->sb.compat & (1ULL << BCH_COMPAT_bformat_overflow_done))) {
+               bch_err(c, "filesystem may have incompatible bkey formats; run fsck from the compat branch to fix");
+               ret = -EINVAL;
+               goto err;
+       }
 
-       if (!c->replicas.entries ||
-           c->opts.rebuild_replicas) {
-               bch_info(c, "building replicas info");
-               set_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
+       if (!(c->sb.features & (1ULL << BCH_FEATURE_alloc_v2))) {
+               bch_info(c, "alloc_v2 feature bit not set, fsck required");
+               c->opts.fsck = true;
+               c->opts.fix_errors = FSCK_OPT_YES;
+       }
+
+       if (!c->opts.nochanges) {
+               if (c->sb.version < bcachefs_metadata_version_no_bps_in_alloc_keys) {
+                       bch_info(c, "version prior to no_bps_in_alloc_keys, upgrade and fsck required");
+                       c->opts.version_upgrade = true;
+                       c->opts.fsck            = true;
+                       c->opts.fix_errors      = FSCK_OPT_YES;
+               }
+       }
+
+       if (c->opts.fsck && c->opts.norecovery) {
+               bch_err(c, "cannot select both norecovery and fsck");
+               ret = -EINVAL;
+               goto err;
+       }
+
+       ret = bch2_blacklist_table_initialize(c);
+       if (ret) {
+               bch_err(c, "error initializing blacklist table");
+               goto err;
        }
 
        if (!c->sb.clean || c->opts.fsck || c->opts.keep_journal) {
-               struct jset *j;
+               struct genradix_iter iter;
+               struct journal_replay **i;
 
-               ret = bch2_journal_read(c, &c->journal_entries);
+               bch_verbose(c, "starting journal read");
+               ret = bch2_journal_read(c, &last_seq, &blacklist_seq, &journal_seq);
                if (ret)
                        goto err;
 
-               if (mustfix_fsck_err_on(c->sb.clean && !journal_empty(&c->journal_entries), c,
+               /*
+                * note: cmd_list_journal needs the blacklist table fully up to date so
+                * it can asterisk ignored journal entries:
+                */
+               if (c->opts.read_journal_only)
+                       goto out;
+
+               genradix_for_each_reverse(&c->journal_entries, iter, i)
+                       if (*i && !(*i)->ignore) {
+                               last_journal_entry = &(*i)->j;
+                               break;
+                       }
+
+               if (mustfix_fsck_err_on(c->sb.clean &&
+                                       last_journal_entry &&
+                                       !journal_entry_empty(last_journal_entry), c,
                                "filesystem marked clean but journal not empty")) {
-                       c->sb.compat &= ~(1ULL << BCH_COMPAT_FEAT_ALLOC_INFO);
+                       c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                        SET_BCH_SB_CLEAN(c->disk_sb.sb, false);
                        c->sb.clean = false;
                }
 
-               if (!c->sb.clean && list_empty(&c->journal_entries)) {
-                       bch_err(c, "no journal entries found");
-                       ret = BCH_FSCK_REPAIR_IMPOSSIBLE;
-                       goto err;
-               }
+               if (!last_journal_entry) {
+                       fsck_err_on(!c->sb.clean, c, "no journal entries found");
+                       if (clean)
+                               goto use_clean;
 
-               c->journal_keys = journal_keys_sort(&c->journal_entries);
-               if (!c->journal_keys.d) {
-                       ret = -ENOMEM;
-                       goto err;
+                       genradix_for_each_reverse(&c->journal_entries, iter, i)
+                               if (*i) {
+                                       last_journal_entry = &(*i)->j;
+                                       (*i)->ignore = false;
+                                       break;
+                               }
                }
 
-               j = &list_last_entry(&c->journal_entries,
-                                    struct journal_replay, list)->j;
-
-               ret = verify_superblock_clean(c, &clean, j);
+               ret = journal_keys_sort(c);
                if (ret)
                        goto err;
 
-               journal_seq = le64_to_cpu(j->seq) + 1;
+               if (c->sb.clean && last_journal_entry) {
+                       ret = verify_superblock_clean(c, &clean,
+                                                     last_journal_entry);
+                       if (ret)
+                               goto err;
+               }
        } else {
-               journal_seq = le64_to_cpu(clean->journal_seq) + 1;
+use_clean:
+               if (!clean) {
+                       bch_err(c, "no superblock clean section found");
+                       ret = -BCH_ERR_fsck_repair_impossible;
+                       goto err;
+
+               }
+               blacklist_seq = journal_seq = le64_to_cpu(clean->journal_seq) + 1;
        }
 
-       if (!c->sb.clean &&
-           !(c->sb.features & (1ULL << BCH_FEATURE_extents_above_btree_updates))) {
-               bch_err(c, "filesystem needs recovery from older version; run fsck from older bcachefs-tools to fix");
-               ret = -EINVAL;
-               goto err;
+       if (c->opts.reconstruct_alloc) {
+               c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
+               drop_alloc_keys(&c->journal_keys);
        }
 
-       ret = journal_replay_early(c, clean, &c->journal_entries);
+       zero_out_btree_mem_ptr(&c->journal_keys);
+
+       ret = journal_replay_early(c, clean);
        if (ret)
                goto err;
 
-       if (!c->sb.clean) {
-               ret = bch2_journal_seq_blacklist_add(c,
-                                                    journal_seq,
-                                                    journal_seq + 4);
+       /*
+        * After an unclean shutdown, skip then next few journal sequence
+        * numbers as they may have been referenced by btree writes that
+        * happened before their corresponding journal writes - those btree
+        * writes need to be ignored, by skipping and blacklisting the next few
+        * journal sequence numbers:
+        */
+       if (!c->sb.clean)
+               journal_seq += 8;
+
+       if (blacklist_seq != journal_seq) {
+               ret =   bch2_journal_log_msg(c, "blacklisting entries %llu-%llu",
+                                            blacklist_seq, journal_seq) ?:
+                       bch2_journal_seq_blacklist_add(c,
+                                       blacklist_seq, journal_seq);
                if (ret) {
                        bch_err(c, "error creating new journal seq blacklist entry");
                        goto err;
                }
-
-               journal_seq += 4;
-
-               /*
-                * The superblock needs to be written before we do any btree
-                * node writes: it will be in the read_write() path
-                */
        }
 
-       ret = bch2_blacklist_table_initialize(c);
-
-       if (!list_empty(&c->journal_entries)) {
-               ret = verify_journal_entries_not_blacklisted_or_missing(c,
-                                                       &c->journal_entries);
-               if (ret)
-                       goto err;
-       }
-
-       ret = bch2_fs_journal_start(&c->journal, journal_seq,
-                                   &c->journal_entries);
+       ret =   bch2_journal_log_msg(c, "starting journal at entry %llu, replaying %llu-%llu",
+                                    journal_seq, last_seq, blacklist_seq - 1) ?:
+               bch2_fs_journal_start(&c->journal, journal_seq);
        if (ret)
                goto err;
 
+       if (c->opts.reconstruct_alloc)
+               bch2_journal_log_msg(c, "dropping alloc info");
+
+       /*
+        * Skip past versions that might have possibly been used (as nonces),
+        * but hadn't had their pointers written:
+        */
+       if (c->sb.encryption_type && !c->sb.clean)
+               atomic64_add(1 << 16, &c->key_version);
+
        ret = read_btree_roots(c);
        if (ret)
                goto err;
 
        bch_verbose(c, "starting alloc read");
        err = "error reading allocation information";
-       ret = bch2_alloc_read(c, &c->journal_keys);
+
+       down_read(&c->gc_lock);
+       ret = c->sb.version < bcachefs_metadata_version_bucket_gens
+               ? bch2_alloc_read(c)
+               : bch2_bucket_gens_read(c);
+       up_read(&c->gc_lock);
+
        if (ret)
                goto err;
        bch_verbose(c, "alloc read done");
 
        bch_verbose(c, "starting stripes_read");
        err = "error reading stripes";
-       ret = bch2_stripes_read(c, &c->journal_keys);
+       ret = bch2_stripes_read(c);
        if (ret)
                goto err;
        bch_verbose(c, "stripes_read done");
 
-       set_bit(BCH_FS_ALLOC_READ_DONE, &c->flags);
+       if (c->sb.version < bcachefs_metadata_version_snapshot_2) {
+               err = "error creating root snapshot node";
+               ret = bch2_fs_initialize_subvolumes(c);
+               if (ret)
+                       goto err;
+       }
 
-       if ((c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_INFO)) &&
-           !(c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_METADATA))) {
-               /*
-                * interior btree node updates aren't consistent with the
-                * journal; after an unclean shutdown we have to walk all
-                * pointers to metadata:
-                */
-               bch_info(c, "starting metadata mark and sweep");
-               err = "error in mark and sweep";
-               ret = bch2_gc(c, &c->journal_keys, true, true);
-               if (ret < 0)
+       bch_verbose(c, "reading snapshots table");
+       err = "error reading snapshots table";
+       ret = bch2_fs_snapshots_start(c);
+       if (ret)
+               goto err;
+       bch_verbose(c, "reading snapshots done");
+
+       if (c->opts.fsck) {
+               bool metadata_only = c->opts.norecovery;
+
+               bch_info(c, "checking allocations");
+               err = "error checking allocations";
+               ret = bch2_gc(c, true, metadata_only);
+               if (ret)
                        goto err;
+               bch_verbose(c, "done checking allocations");
+
+               set_bit(BCH_FS_INITIAL_GC_DONE, &c->flags);
+
+               set_bit(BCH_FS_MAY_GO_RW, &c->flags);
+
+               bch_info(c, "starting journal replay, %zu keys", c->journal_keys.nr);
+               err = "journal replay failed";
+               ret = bch2_journal_replay(c, last_seq, blacklist_seq - 1);
                if (ret)
-                       need_write_alloc = true;
-               bch_verbose(c, "mark and sweep done");
-       }
+                       goto err;
+               if (c->opts.verbose || !c->sb.clean)
+                       bch_info(c, "journal replay done");
 
-       if (c->opts.fsck ||
-           !(c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_INFO)) ||
-           test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags)) {
-               bch_info(c, "starting mark and sweep");
-               err = "error in mark and sweep";
-               ret = bch2_gc(c, &c->journal_keys, true, false);
-               if (ret < 0)
+               bch_info(c, "checking need_discard and freespace btrees");
+               err = "error checking need_discard and freespace btrees";
+               ret = bch2_check_alloc_info(c);
+               if (ret)
                        goto err;
+               bch_verbose(c, "done checking need_discard and freespace btrees");
+
+               set_bit(BCH_FS_CHECK_ALLOC_DONE, &c->flags);
+
+               bch_info(c, "checking lrus");
+               err = "error checking lrus";
+               ret = bch2_check_lrus(c);
                if (ret)
-                       need_write_alloc = true;
-               bch_verbose(c, "mark and sweep done");
-       }
+                       goto err;
+               bch_verbose(c, "done checking lrus");
+               set_bit(BCH_FS_CHECK_LRUS_DONE, &c->flags);
 
-       clear_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
-       set_bit(BCH_FS_INITIAL_GC_DONE, &c->flags);
+               bch_info(c, "checking backpointers to alloc keys");
+               err = "error checking backpointers to alloc keys";
+               ret = bch2_check_btree_backpointers(c);
+               if (ret)
+                       goto err;
+               bch_verbose(c, "done checking backpointers to alloc keys");
 
-       /*
-        * Skip past versions that might have possibly been used (as nonces),
-        * but hadn't had their pointers written:
-        */
-       if (c->sb.encryption_type && !c->sb.clean)
-               atomic64_add(1 << 16, &c->key_version);
+               bch_info(c, "checking backpointers to extents");
+               err = "error checking backpointers to extents";
+               ret = bch2_check_backpointers_to_extents(c);
+               if (ret)
+                       goto err;
+               bch_verbose(c, "done checking backpointers to extents");
 
-       if (c->opts.norecovery)
-               goto out;
+               bch_info(c, "checking extents to backpointers");
+               err = "error checking extents to backpointers";
+               ret = bch2_check_extents_to_backpointers(c);
+               if (ret)
+                       goto err;
+               bch_verbose(c, "done checking extents to backpointers");
+               set_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags);
+
+               bch_info(c, "checking alloc to lru refs");
+               err = "error checking alloc to lru refs";
+               ret = bch2_check_alloc_to_lru_refs(c);
+               if (ret)
+                       goto err;
+               bch_verbose(c, "done checking alloc to lru refs");
+               set_bit(BCH_FS_CHECK_ALLOC_TO_LRU_REFS_DONE, &c->flags);
+       } else {
+               set_bit(BCH_FS_INITIAL_GC_DONE, &c->flags);
+               set_bit(BCH_FS_CHECK_ALLOC_DONE, &c->flags);
+               set_bit(BCH_FS_CHECK_LRUS_DONE, &c->flags);
+               set_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags);
+               set_bit(BCH_FS_CHECK_ALLOC_TO_LRU_REFS_DONE, &c->flags);
+               set_bit(BCH_FS_FSCK_DONE, &c->flags);
+
+               if (c->opts.norecovery)
+                       goto out;
 
-       bch_verbose(c, "starting journal replay");
-       err = "journal replay failed";
-       ret = bch2_journal_replay(c, c->journal_keys);
+               set_bit(BCH_FS_MAY_GO_RW, &c->flags);
+
+               bch_verbose(c, "starting journal replay, %zu keys", c->journal_keys.nr);
+               err = "journal replay failed";
+               ret = bch2_journal_replay(c, last_seq, blacklist_seq - 1);
+               if (ret)
+                       goto err;
+               if (c->opts.verbose || !c->sb.clean)
+                       bch_info(c, "journal replay done");
+       }
+
+       err = "error initializing freespace";
+       ret = bch2_fs_freespace_init(c);
        if (ret)
                goto err;
-       bch_verbose(c, "journal replay done");
 
-       if (need_write_alloc && !c->opts.nochanges) {
-               /*
-                * note that even when filesystem was clean there might be work
-                * to do here, if we ran gc (because of fsck) which recalculated
-                * oldest_gen:
-                */
-               bch_verbose(c, "writing allocation info");
-               err = "error writing out alloc info";
-               ret = bch2_stripes_write(c, BTREE_INSERT_LAZY_RW) ?:
-                       bch2_alloc_write(c, BTREE_INSERT_LAZY_RW);
-               if (ret) {
-                       bch_err(c, "error writing alloc info");
+       if (c->sb.version < bcachefs_metadata_version_bucket_gens &&
+           c->opts.version_upgrade) {
+               bch_info(c, "initializing bucket_gens");
+               err = "error initializing bucket gens";
+               ret = bch2_bucket_gens_init(c);
+               if (ret)
                        goto err;
-               }
-               bch_verbose(c, "alloc write done");
-
-               set_bit(BCH_FS_ALLOC_WRITTEN, &c->flags);
+               bch_verbose(c, "bucket_gens init done");
        }
 
-       if (!c->sb.clean) {
-               if (!(c->sb.features & (1 << BCH_FEATURE_atomic_nlink))) {
-                       bch_info(c, "checking inode link counts");
-                       err = "error in recovery";
-                       ret = bch2_fsck_inode_nlink(c);
-                       if (ret)
-                               goto err;
-                       bch_verbose(c, "check inodes done");
-
-               } else {
-                       bch_verbose(c, "checking for deleted inodes");
-                       err = "error in recovery";
-                       ret = bch2_fsck_walk_inodes_only(c);
-                       if (ret)
-                               goto err;
-                       bch_verbose(c, "check inodes done");
-               }
+       if (c->sb.version < bcachefs_metadata_version_snapshot_2) {
+               /* set bi_subvol on root inode */
+               err = "error upgrade root inode for subvolumes";
+               ret = bch2_trans_do(c, NULL, NULL, BTREE_INSERT_LAZY_RW,
+                                   bch2_fs_upgrade_for_subvolumes(&trans));
+               if (ret)
+                       goto err;
        }
 
        if (c->opts.fsck) {
@@ -1177,6 +1428,13 @@ int bch2_fs_recovery(struct bch_fs *c)
                if (ret)
                        goto err;
                bch_verbose(c, "fsck done");
+       } else if (!c->sb.clean) {
+               bch_verbose(c, "checking for deleted inodes");
+               err = "error in recovery";
+               ret = bch2_fsck_walk_inodes_only(c);
+               if (ret)
+                       goto err;
+               bch_verbose(c, "check inodes done");
        }
 
        if (enabled_qtypes(c)) {
@@ -1189,23 +1447,21 @@ int bch2_fs_recovery(struct bch_fs *c)
 
        mutex_lock(&c->sb_lock);
        if (c->opts.version_upgrade) {
-               if (c->sb.version < bcachefs_metadata_version_new_versioning)
-                       c->disk_sb.sb->version_min =
-                               le16_to_cpu(bcachefs_metadata_version_min);
-               c->disk_sb.sb->version = le16_to_cpu(bcachefs_metadata_version_current);
-               c->disk_sb.sb->features[0] |= BCH_SB_FEATURES_ALL;
+               c->disk_sb.sb->version = cpu_to_le16(bcachefs_metadata_version_current);
+               c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_SB_FEATURES_ALL);
                write_sb = true;
        }
 
        if (!test_bit(BCH_FS_ERROR, &c->flags)) {
-               c->disk_sb.sb->compat[0] |= 1ULL << BCH_COMPAT_FEAT_ALLOC_INFO;
+               c->disk_sb.sb->compat[0] |= cpu_to_le64(1ULL << BCH_COMPAT_alloc_info);
                write_sb = true;
        }
 
        if (c->opts.fsck &&
-           !test_bit(BCH_FS_ERROR, &c->flags)) {
-               c->disk_sb.sb->features[0] |= 1ULL << BCH_FEATURE_atomic_nlink;
+           !test_bit(BCH_FS_ERROR, &c->flags) &&
+           !test_bit(BCH_FS_ERRORS_NOT_FIXED, &c->flags)) {
                SET_BCH_SB_HAS_ERRORS(c->disk_sb.sb, 0);
+               SET_BCH_SB_HAS_TOPOLOGY_ERRORS(c->disk_sb.sb, 0);
                write_sb = true;
        }
 
@@ -1213,26 +1469,54 @@ int bch2_fs_recovery(struct bch_fs *c)
                bch2_write_super(c);
        mutex_unlock(&c->sb_lock);
 
+       if (!(c->sb.compat & (1ULL << BCH_COMPAT_extents_above_btree_updates_done)) ||
+           !(c->sb.compat & (1ULL << BCH_COMPAT_bformat_overflow_done)) ||
+           le16_to_cpu(c->sb.version_min) < bcachefs_metadata_version_btree_ptr_sectors_written) {
+               struct bch_move_stats stats;
+
+               bch2_move_stats_init(&stats, "recovery");
+
+               bch_info(c, "scanning for old btree nodes");
+               ret = bch2_fs_read_write(c);
+               if (ret)
+                       goto err;
+
+               ret = bch2_scan_old_btree_nodes(c, &stats);
+               if (ret)
+                       goto err;
+               bch_info(c, "scanning for old btree nodes done");
+       }
+
        if (c->journal_seq_blacklist_table &&
            c->journal_seq_blacklist_table->nr > 128)
                queue_work(system_long_wq, &c->journal_seq_blacklist_gc_work);
-out:
+
        ret = 0;
-err:
-fsck_err:
+out:
        set_bit(BCH_FS_FSCK_DONE, &c->flags);
        bch2_flush_fsck_errs(c);
 
-       if (!c->opts.keep_journal) {
+       if (!c->opts.keep_journal &&
+           test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)) {
                bch2_journal_keys_free(&c->journal_keys);
-               bch2_journal_entries_free(&c->journal_entries);
+               bch2_journal_entries_free(c);
        }
        kfree(clean);
+
+       if (!ret && test_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags)) {
+               bch2_fs_read_write_early(c);
+               bch2_delete_dead_snapshots_async(c);
+       }
+
        if (ret)
-               bch_err(c, "Error in recovery: %s (%i)", err, ret);
+               bch_err(c, "Error in recovery: %s (%s)", err, bch2_err_str(ret));
        else
-               bch_verbose(c, "ret %i", ret);
+               bch_verbose(c, "ret %s", bch2_err_str(ret));
        return ret;
+err:
+fsck_err:
+       bch2_fs_emergency_read_only(c);
+       goto out;
 }
 
 int bch2_fs_initialize(struct bch_fs *c)
@@ -1242,34 +1526,37 @@ int bch2_fs_initialize(struct bch_fs *c)
        struct qstr lostfound = QSTR("lost+found");
        const char *err = "cannot allocate memory";
        struct bch_dev *ca;
-       LIST_HEAD(journal);
        unsigned i;
        int ret;
 
        bch_notice(c, "initializing new filesystem");
 
        mutex_lock(&c->sb_lock);
-       for_each_online_member(ca, c, i)
-               bch2_mark_dev_superblock(c, ca, 0);
-       mutex_unlock(&c->sb_lock);
+       c->disk_sb.sb->compat[0] |= cpu_to_le64(1ULL << BCH_COMPAT_extents_above_btree_updates_done);
+       c->disk_sb.sb->compat[0] |= cpu_to_le64(1ULL << BCH_COMPAT_bformat_overflow_done);
 
-       mutex_lock(&c->sb_lock);
-       c->disk_sb.sb->version = c->disk_sb.sb->version_min =
-               le16_to_cpu(bcachefs_metadata_version_current);
-       c->disk_sb.sb->features[0] |= 1ULL << BCH_FEATURE_atomic_nlink;
-       c->disk_sb.sb->features[0] |= BCH_SB_FEATURES_ALL;
+       if (c->sb.version < bcachefs_metadata_version_inode_v3)
+               c->opts.version_upgrade = true;
 
-       bch2_write_super(c);
+       if (c->opts.version_upgrade) {
+               c->disk_sb.sb->version = cpu_to_le16(bcachefs_metadata_version_current);
+               c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_SB_FEATURES_ALL);
+               bch2_write_super(c);
+       }
        mutex_unlock(&c->sb_lock);
 
-       set_bit(BCH_FS_ALLOC_READ_DONE, &c->flags);
        set_bit(BCH_FS_INITIAL_GC_DONE, &c->flags);
+       set_bit(BCH_FS_CHECK_LRUS_DONE, &c->flags);
+       set_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags);
+       set_bit(BCH_FS_CHECK_ALLOC_TO_LRU_REFS_DONE, &c->flags);
+       set_bit(BCH_FS_MAY_GO_RW, &c->flags);
+       set_bit(BCH_FS_FSCK_DONE, &c->flags);
 
        for (i = 0; i < BTREE_ID_NR; i++)
                bch2_btree_root_alloc(c, i);
 
-       set_bit(BCH_FS_BTREE_INTERIOR_REPLAY_DONE, &c->flags);
-       set_bit(JOURNAL_RECLAIM_STARTED, &c->journal.flags);
+       for_each_online_member(ca, c, i)
+               bch2_dev_usage_init(ca);
 
        err = "unable to allocate journal buckets";
        for_each_online_member(ca, c, i) {
@@ -1284,7 +1571,7 @@ int bch2_fs_initialize(struct bch_fs *c)
         * journal_res_get() will crash if called before this has
         * set up the journal.pin FIFO and journal.cur pointer:
         */
-       bch2_fs_journal_start(&c->journal, 1, &journal);
+       bch2_fs_journal_start(&c->journal, 1);
        bch2_journal_set_replay_done(&c->journal);
 
        err = "error going read-write";
@@ -1296,18 +1583,44 @@ int bch2_fs_initialize(struct bch_fs *c)
         * Write out the superblock and journal buckets, now that we can do
         * btree updates
         */
-       err = "error writing alloc info";
-       ret = bch2_alloc_write(c, 0);
+       bch_verbose(c, "marking superblocks");
+       err = "error marking superblock and journal";
+       for_each_member_device(ca, c, i) {
+               ret = bch2_trans_mark_dev_sb(c, ca);
+               if (ret) {
+                       percpu_ref_put(&ca->ref);
+                       goto err;
+               }
+
+               ca->new_fs_bucket_idx = 0;
+       }
+
+       bch_verbose(c, "initializing freespace");
+       err = "error initializing freespace";
+       ret = bch2_fs_freespace_init(c);
        if (ret)
                goto err;
 
-       bch2_inode_init(c, &root_inode, 0, 0,
-                       S_IFDIR|S_IRWXU|S_IRUGO|S_IXUGO, 0, NULL);
-       root_inode.bi_inum = BCACHEFS_ROOT_INO;
+       err = "error creating root snapshot node";
+       ret = bch2_fs_initialize_subvolumes(c);
+       if (ret)
+               goto err;
+
+       bch_verbose(c, "reading snapshots table");
+       err = "error reading snapshots table";
+       ret = bch2_fs_snapshots_start(c);
+       if (ret)
+               goto err;
+       bch_verbose(c, "reading snapshots done");
+
+       bch2_inode_init(c, &root_inode, 0, 0, S_IFDIR|0755, 0, NULL);
+       root_inode.bi_inum      = BCACHEFS_ROOT_INO;
+       root_inode.bi_subvol    = BCACHEFS_ROOT_SUBVOL;
        bch2_inode_pack(&packed_inode, &root_inode);
+       packed_inode.inode.k.p.snapshot = U32_MAX;
 
        err = "error creating root directory";
-       ret = bch2_btree_insert(c, BTREE_ID_INODES,
+       ret = bch2_btree_insert(c, BTREE_ID_inodes,
                                &packed_inode.inode.k_i,
                                NULL, NULL, 0);
        if (ret)
@@ -1317,13 +1630,16 @@ int bch2_fs_initialize(struct bch_fs *c)
 
        err = "error creating lost+found";
        ret = bch2_trans_do(c, NULL, NULL, 0,
-               bch2_create_trans(&trans, BCACHEFS_ROOT_INO,
+               bch2_create_trans(&trans,
+                                 BCACHEFS_ROOT_SUBVOL_INUM,
                                  &root_inode, &lostfound_inode,
                                  &lostfound,
                                  0, 0, S_IFDIR|0700, 0,
-                                 NULL, NULL));
-       if (ret)
+                                 NULL, NULL, (subvol_inum) { 0 }, 0));
+       if (ret) {
+               bch_err(c, "error creating lost+found");
                goto err;
+       }
 
        if (enabled_qtypes(c)) {
                ret = bch2_fs_quota_read(c);
@@ -1332,7 +1648,7 @@ int bch2_fs_initialize(struct bch_fs *c)
        }
 
        err = "error writing first journal entry";
-       ret = bch2_journal_meta(&c->journal);
+       ret = bch2_journal_flush(&c->journal);
        if (ret)
                goto err;
 
@@ -1345,6 +1661,6 @@ int bch2_fs_initialize(struct bch_fs *c)
 
        return 0;
 err:
-       pr_err("Error initializing new filesystem: %s (%i)", err, ret);
+       pr_err("Error initializing new filesystem: %s (%s)", err, bch2_err_str(ret));
        return ret;
 }