]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/recovery.c
Update bcachefs sources to 5e392aed7a bcachefs: Kill bch2_alloc_write()
[bcachefs-tools-debian] / libbcachefs / recovery.c
index f86b041823c4ef9fe112598efa7b88b0b5393224..ca92fe84c248a25f5863046bdc038f265274e20d 100644 (file)
 #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>
@@ -32,34 +35,46 @@ 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)
+               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 int __journal_key_cmp(enum btree_id     l_btree_id,
                             unsigned           l_level,
                             struct bpos        l_pos,
-                            struct journal_key *r)
+                            const struct journal_key *r)
 {
        return (cmp_int(l_btree_id,     r->btree_id) ?:
                cmp_int(l_level,        r->level) ?:
-               bkey_cmp(l_pos, r->k->k.p));
+               bpos_cmp(l_pos, r->k->k.p));
 }
 
-static int journal_key_cmp(struct journal_key *l, struct journal_key *r)
+static int journal_key_cmp(const struct journal_key *l, const struct journal_key *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->btree_id, l->level, l->k->k.p, r);
 }
 
-static size_t journal_key_search(struct journal_keys *journal_keys,
-                                enum btree_id id, unsigned level,
-                                struct bpos pos)
+size_t bch2_journal_key_search(struct journal_keys *journal_keys,
+                              enum btree_id id, unsigned level,
+                              struct bpos pos)
 {
        size_t l = 0, r = journal_keys->nr, m;
 
@@ -80,6 +95,24 @@ static size_t journal_key_search(struct journal_keys *journal_keys,
        return l;
 }
 
+struct bkey_i *bch2_journal_keys_peek(struct bch_fs *c, enum btree_id btree_id,
+                                     unsigned level, struct bpos pos)
+{
+       struct journal_keys *keys = &c->journal_keys;
+       struct journal_key *end = keys->d + keys->nr;
+       struct journal_key *k = keys->d +
+               bch2_journal_key_search(keys, btree_id, level, pos);
+
+       while (k < end && k->overwritten)
+               k++;
+
+       if (k < end &&
+           k->btree_id == btree_id &&
+           k->level    == level)
+               return k->k;
+       return NULL;
+}
+
 static void journal_iter_fix(struct bch_fs *c, struct journal_iter *iter, unsigned idx)
 {
        struct bkey_i *n = iter->keys->d[idx].k;
@@ -89,22 +122,29 @@ static void journal_iter_fix(struct bch_fs *c, struct journal_iter *iter, unsign
        if (iter->idx > idx ||
            (iter->idx == idx &&
             biter->last &&
-            bkey_cmp(n->k.p, biter->unpacked.p) <= 0))
+            bpos_cmp(n->k.p, biter->unpacked.p) <= 0))
                iter->idx++;
 }
 
-int bch2_journal_key_insert(struct bch_fs *c, enum btree_id id,
-                           unsigned level, struct bkey_i *k)
+int bch2_journal_key_insert_take(struct bch_fs *c, enum btree_id id,
+                                unsigned level, struct bkey_i *k)
 {
        struct journal_key n = {
                .btree_id       = id,
                .level          = level,
                .k              = k,
-               .allocated      = true
+               .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;
        struct journal_iter *iter;
-       unsigned idx = journal_key_search(keys, id, level, k->k.p);
+       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->nr &&
            journal_key_cmp(&n, &keys->d[idx]) == 0) {
@@ -122,8 +162,11 @@ int bch2_journal_key_insert(struct bch_fs *c, enum btree_id id,
                };
 
                new_keys.d = kvmalloc(sizeof(new_keys.d[0]) * new_keys.size, GFP_KERNEL);
-               if (!new_keys.d)
+               if (!new_keys.d) {
+                       bch_err(c, "%s: error allocating new key array (size %zu)",
+                               __func__, new_keys.size);
                        return -ENOMEM;
+               }
 
                memcpy(new_keys.d, keys->d, sizeof(keys->d[0]) * keys->nr);
                kvfree(keys->d);
@@ -138,36 +181,66 @@ int bch2_journal_key_insert(struct bch_fs *c, enum btree_id id,
        return 0;
 }
 
-int bch2_journal_key_delete(struct bch_fs *c, enum btree_id id,
-                           unsigned level, struct bpos pos)
+/*
+ * 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 *whiteout =
-               kmalloc(sizeof(struct bkey), GFP_KERNEL);
+       struct bkey_i *n;
        int ret;
 
-       if (!whiteout)
+       n = kmalloc(bkey_bytes(&k->k), GFP_KERNEL);
+       if (!n)
                return -ENOMEM;
 
-       bkey_init(&whiteout->k);
-       whiteout->k.p = pos;
-
-       ret = bch2_journal_key_insert(c, id, level, whiteout);
+       bkey_copy(n, k);
+       ret = bch2_journal_key_insert_take(c, id, level, n);
        if (ret)
-               kfree(whiteout);
+               kfree(n);
        return ret;
 }
 
+int bch2_journal_key_delete(struct bch_fs *c, enum btree_id id,
+                           unsigned level, struct bpos pos)
+{
+       struct bkey_i whiteout;
+
+       bkey_init(&whiteout.k);
+       whiteout.k.p = pos;
+
+       return bch2_journal_key_insert(c, id, level, &whiteout);
+}
+
+void bch2_journal_key_overwritten(struct bch_fs *c, enum btree_id btree,
+                                 unsigned level, struct bpos pos)
+{
+       struct journal_keys *keys = &c->journal_keys;
+       size_t idx = bch2_journal_key_search(keys, btree, level, pos);
+
+       if (idx < keys->nr &&
+           keys->d[idx].btree_id       == btree &&
+           keys->d[idx].level          == level &&
+           !bpos_cmp(keys->d[idx].k->k.p, pos))
+               keys->d[idx].overwritten = true;
+}
+
 static struct bkey_i *bch2_journal_iter_peek(struct journal_iter *iter)
 {
-       struct journal_key *k = iter->idx - iter->keys->nr
-               ? iter->keys->d + iter->idx : NULL;
+       struct journal_key *k = iter->keys->d + iter->idx;
 
-       if (k &&
-           k->btree_id == iter->btree_id &&
-           k->level    == iter->level)
-               return k->k;
+       while (k < iter->keys->d + iter->keys->nr &&
+              k->btree_id      == iter->btree_id &&
+              k->level         == iter->level) {
+               if (!k->overwritten)
+                       return k->k;
+
+               iter->idx++;
+               k = iter->keys->d + iter->idx;
+       }
 
-       iter->idx = iter->keys->nr;
        return NULL;
 }
 
@@ -190,8 +263,7 @@ static void bch2_journal_iter_init(struct bch_fs *c,
        iter->btree_id  = id;
        iter->level     = level;
        iter->keys      = &c->journal_keys;
-       iter->idx       = journal_key_search(&c->journal_keys, id, level, pos);
-       list_add(&iter->list, &c->journal_iters);
+       iter->idx       = bch2_journal_key_search(&c->journal_keys, id, level, pos);
 }
 
 static struct bkey_s_c bch2_journal_iter_peek_btree(struct btree_and_journal_iter *iter)
@@ -232,7 +304,7 @@ struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *
                        bkey_i_to_s_c(bch2_journal_iter_peek(&iter->journal));
 
                if (btree_k.k && journal_k.k) {
-                       int cmp = bkey_cmp(btree_k.k->p, journal_k.k->p);
+                       int cmp = bpos_cmp(btree_k.k->p, journal_k.k->p);
 
                        if (!cmp)
                                bch2_journal_iter_advance_btree(iter);
@@ -250,7 +322,7 @@ struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *
                ret = iter->last == journal ? journal_k : btree_k;
 
                if (iter->b &&
-                   bkey_cmp(ret.k->p, iter->b->data->max_key) > 0) {
+                   bpos_cmp(ret.k->p, iter->b->data->max_key) > 0) {
                        iter->journal.idx = iter->journal.keys->nr;
                        iter->last = none;
                        return bkey_s_c_null;
@@ -277,116 +349,33 @@ void bch2_btree_and_journal_iter_exit(struct btree_and_journal_iter *iter)
        bch2_journal_iter_exit(&iter->journal);
 }
 
-void bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter *iter,
-                                               struct bch_fs *c,
-                                               struct btree *b)
+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));
 
        iter->b = b;
-       bch2_btree_node_iter_init_from_start(&iter->node_iter, iter->b);
-       bch2_journal_iter_init(c, &iter->journal,
-                              b->c.btree_id, b->c.level, b->data->min_key);
-}
-
-/* Walk btree, overlaying keys from the journal: */
-
-static void btree_and_journal_iter_prefetch(struct bch_fs *c, struct btree *b,
-                                          struct btree_and_journal_iter iter)
-{
-       unsigned i = 0, nr = b->c.level > 1 ? 2 : 16;
-       struct bkey_s_c k;
-       struct bkey_buf tmp;
-
-       BUG_ON(!b->c.level);
-
-       bch2_bkey_buf_init(&tmp);
-
-       while (i < nr &&
-              (k = bch2_btree_and_journal_iter_peek(&iter)).k) {
-               bch2_bkey_buf_reassemble(&tmp, c, k);
-
-               bch2_btree_node_prefetch(c, NULL, tmp.k,
-                                       b->c.btree_id, b->c.level - 1);
-
-               bch2_btree_and_journal_iter_advance(&iter);
-               i++;
-       }
-
-       bch2_bkey_buf_exit(&tmp, c);
-}
-
-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)
-{
-       struct btree_and_journal_iter iter;
-       struct bkey_s_c k;
-       struct bkey_buf tmp;
-       struct btree *child;
-       int ret = 0;
-
-       bch2_bkey_buf_init(&tmp);
-       bch2_btree_and_journal_iter_init_node_iter(&iter, c, b);
-
-       while ((k = bch2_btree_and_journal_iter_peek(&iter)).k) {
-               ret = key_fn(c, btree_id, b->c.level, k);
-               if (ret)
-                       break;
-
-               if (b->c.level) {
-                       bch2_bkey_buf_reassemble(&tmp, c, k);
-
-                       bch2_btree_and_journal_iter_advance(&iter);
-
-                       child = bch2_btree_node_get_noiter(c, tmp.k,
-                                               b->c.btree_id, b->c.level - 1,
-                                               false);
-
-                       ret = PTR_ERR_OR_ZERO(child);
-                       if (ret)
-                               break;
-
-                       btree_and_journal_iter_prefetch(c, b, iter);
-
-                       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);
-
-                       if (ret)
-                               break;
-               } else {
-                       bch2_btree_and_journal_iter_advance(&iter);
-               }
-       }
-
-       bch2_btree_and_journal_iter_exit(&iter);
-       bch2_bkey_buf_exit(&tmp, c);
-       return ret;
+       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);
 }
 
-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)
+/*
+ * 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 *b = c->btree_roots[btree_id].b;
-       int ret = 0;
-
-       if (btree_node_fake(b))
-               return 0;
-
-       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);
+       struct btree_node_iter node_iter;
 
-       return ret;
+       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: */
@@ -411,9 +400,7 @@ 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);
 }
@@ -484,7 +471,7 @@ static struct journal_keys journal_keys_sort(struct list_head *journal_entries)
                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_cmp(src[0].k->k.p, src[1].k->k.p))
                        src++;
 
                *dst++ = *src++;
@@ -506,147 +493,85 @@ static void replay_now_at(struct journal *j, u64 seq)
                bch2_journal_pin_put(j, j->replay_journal_seq++);
 }
 
-static int __bch2_journal_replay_key(struct btree_trans *trans,
-                                    enum btree_id id, unsigned level,
-                                    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_node_iter(trans, id, k->k.p,
-                                       BTREE_MAX_DEPTH, level,
-                                       BTREE_ITER_INTENT);
-
-       /*
-        * 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);
-
-       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, struct journal_key *k)
-{
-       unsigned commit_flags = BTREE_INSERT_NOFAIL|
-               BTREE_INSERT_LAZY_RW;
+       if (!k->level && k->btree_id == BTREE_ID_alloc)
+               iter_flags |= BTREE_ITER_CACHED;
 
-       if (!k->allocated)
-               commit_flags |= BTREE_INSERT_JOURNAL_REPLAY;
-
-       return bch2_trans_do(c, NULL, NULL, commit_flags,
-                            __bch2_journal_replay_key(&trans, k->btree_id, k->level, k->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;
 
-static int __bch2_alloc_replay_key(struct btree_trans *trans, struct bkey_i *k)
-{
-       struct btree_iter *iter;
-       int ret;
+       /* Must be checked with btree locked: */
+       if (k->overwritten)
+               goto out;
 
-       iter = bch2_trans_get_iter(trans, BTREE_ID_ALLOC, k->k.p,
-                                  BTREE_ITER_CACHED|
-                                  BTREE_ITER_CACHED_NOFILL|
-                                  BTREE_ITER_INTENT);
-       ret = bch2_trans_update(trans, iter, k, BTREE_TRIGGER_NORUN);
-       bch2_trans_iter_put(trans, iter);
+       ret = bch2_trans_update(trans, &iter, k->k, BTREE_TRIGGER_NORUN);
+out:
+       bch2_trans_iter_exit(trans, &iter);
        return ret;
 }
 
-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));
-}
-
 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)
 {
+       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;
-               }
-       }
+       keys_sorted = kvmalloc_array(sizeof(*keys_sorted), keys->nr, GFP_KERNEL);
+       if (!keys_sorted)
+               return -ENOMEM;
 
-       /*
-        * Next replay updates to interior btree nodes:
-        */
-       for_each_journal_key(keys, i) {
-               cond_resched();
+       for (i = 0; i < keys->nr; i++)
+               keys_sorted[i] = &keys->d[i];
 
-               if (i->level) {
-                       j->replay_journal_seq = keys.journal_seq_base + i->journal_seq;
-                       ret = bch2_journal_replay_key(c, i);
-                       if (ret)
-                               goto err;
-               }
-       }
+       sort(keys_sorted, keys->nr,
+            sizeof(keys_sorted[0]),
+            journal_sort_seq_cmp, NULL);
 
-       /*
-        * 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);
-       journal_reclaim_kick(j);
+       if (keys->nr)
+               replay_now_at(j, keys->journal_seq_base);
 
-       j->replay_journal_seq = seq;
+       for (i = 0; i < keys->nr; i++) {
+               k = keys_sorted[i];
 
-       /*
-        * Now replay leaf node updates:
-        */
-       for_each_journal_key(keys, i) {
                cond_resched();
 
-               if (i->level || i->btree_id == BTREE_ID_ALLOC)
-                       continue;
+               if (!k->allocated)
+                       replay_now_at(j, keys->journal_seq_base + k->journal_seq);
 
-               replay_now_at(j, keys.journal_seq_base + i->journal_seq);
-
-               ret = bch2_journal_replay_key(c, i);
-               if (ret)
+               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 %d while replaying key at btree %s level %u",
+                               ret, bch2_btree_ids[k->btree_id], k->level);
                        goto err;
+               }
        }
 
        replay_now_at(j, j->replay_journal_seq_end);
@@ -654,10 +579,12 @@ static int bch2_journal_replay(struct bch_fs *c,
 
        bch2_journal_set_replay_done(j);
        bch2_journal_flush_all_pins(j);
-       return bch2_journal_error(j);
+       ret = bch2_journal_error(j);
+
+       if (keys->nr && !ret)
+               bch2_journal_log_msg(&c->journal, "journal replay finished");
 err:
-       bch_err(c, "journal replay: error %d while replaying key at btree %s level %u",
-               ret, bch2_btree_ids[i->btree_id], i->level);
+       kvfree(keys_sorted);
        return ret;
 }
 
@@ -695,15 +622,15 @@ 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;
@@ -722,16 +649,13 @@ static int journal_replay_entry_early(struct bch_fs *c,
        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, u->dev);
-               unsigned bytes = jset_u64s(le16_to_cpu(entry->u64s)) * sizeof(u64);
-               unsigned nr_types = (bytes - sizeof(struct jset_entry_dev_usage)) /
-                       sizeof(struct jset_entry_dev_usage_type);
-               unsigned i;
+               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);
                ca->usage_base->buckets_unavailable     = le64_to_cpu(u->buckets_unavailable);
 
-               for (i = 0; i < nr_types; i++) {
+               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);
@@ -761,7 +685,7 @@ static int journal_replay_entry_early(struct bch_fs *c,
                struct jset_entry_clock *clock =
                        container_of(entry, struct jset_entry_clock, entry);
 
-               atomic64_set(&c->io_clock[clock->rw].now, clock->time);
+               atomic64_set(&c->io_clock[clock->rw].now, le64_to_cpu(clock->time));
        }
        }
 
@@ -841,6 +765,8 @@ 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 (mustfix_fsck_err_on(j->seq != clean->journal_seq, c,
@@ -853,7 +779,6 @@ static int verify_superblock_clean(struct bch_fs *c,
        }
 
        for (i = 0; i < BTREE_ID_NR; i++) {
-               char buf1[200], buf2[200];
                struct bkey_i *k1, *k2;
                unsigned l1 = 0, l2 = 0;
 
@@ -863,6 +788,19 @@ 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
+                       pr_buf(&buf1, "(none)");
+
+               if (k2)
+                       bch2_bkey_val_to_text(&buf2, c, bkey_i_to_s_c(k2));
+               else
+                       pr_buf(&buf2, "(none)");
+
                mustfix_fsck_err_on(!k1 || !k2 ||
                                    IS_ERR(k1) ||
                                    IS_ERR(k2) ||
@@ -872,10 +810,12 @@ static int verify_superblock_clean(struct bch_fs *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;
 }
 
@@ -902,9 +842,11 @@ static struct bch_sb_field_clean *read_superblock_clean(struct bch_fs *c)
                return ERR_PTR(-ENOMEM);
        }
 
-       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);
 
@@ -925,29 +867,29 @@ static int read_btree_roots(struct bch_fs *c)
                if (!r->alive)
                        continue;
 
-               if (i == BTREE_ID_ALLOC &&
+               if (i == BTREE_ID_alloc &&
                    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, i == BTREE_ID_alloc
                                   ? 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, i == BTREE_ID_alloc
                                   ? 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 (i == BTREE_ID_alloc)
+                               c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                }
        }
 
@@ -958,6 +900,73 @@ 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";
@@ -965,7 +974,7 @@ int bch2_fs_recovery(struct bch_fs *c)
        struct jset *last_journal_entry = NULL;
        u64 blacklist_seq, journal_seq;
        bool write_sb = false;
-       int ret;
+       int ret = 0;
 
        if (c->sb.clean)
                clean = read_superblock_clean(c);
@@ -976,6 +985,8 @@ 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");
@@ -983,11 +994,23 @@ int bch2_fs_recovery(struct bch_fs *c)
                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->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;
-               c->disk_sb.sb->features[0] |= 1ULL << BCH_FEATURE_alloc_v2;
        }
 
        if (!c->replicas.entries ||
@@ -996,6 +1019,22 @@ int bch2_fs_recovery(struct bch_fs *c)
                set_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
        }
 
+       if (!c->opts.nochanges) {
+               if (c->sb.version < bcachefs_metadata_version_inode_backpointers) {
+                       bch_info(c, "version prior to inode backpointers, upgrade and fsck required");
+                       c->opts.version_upgrade = true;
+                       c->opts.fsck            = true;
+                       c->opts.fix_errors      = FSCK_OPT_YES;
+               } else if (c->sb.version < bcachefs_metadata_version_subvol_dirent) {
+                       bch_info(c, "filesystem version is prior to subvol_dirent - upgrading");
+                       c->opts.version_upgrade = true;
+                       c->opts.fsck            = true;
+               } else if (c->sb.version < bcachefs_metadata_version_alloc_v4) {
+                       bch_info(c, "filesystem version is prior to alloc_v4 - upgrading");
+                       c->opts.version_upgrade = true;
+               }
+       }
+
        ret = bch2_blacklist_table_initialize(c);
        if (ret) {
                bch_err(c, "error initializing blacklist table");
@@ -1005,6 +1044,7 @@ int bch2_fs_recovery(struct bch_fs *c)
        if (!c->sb.clean || c->opts.fsck || c->opts.keep_journal) {
                struct journal_replay *i;
 
+               bch_verbose(c, "starting journal read");
                ret = bch2_journal_read(c, &c->journal_entries,
                                        &blacklist_seq, &journal_seq);
                if (ret)
@@ -1020,7 +1060,7 @@ int bch2_fs_recovery(struct bch_fs *c)
                                        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;
                }
@@ -1053,18 +1093,16 @@ use_clean:
                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.read_journal_only)
+               goto out;
 
        if (c->opts.reconstruct_alloc) {
-               c->sb.compat &= ~(1ULL << BCH_COMPAT_FEAT_ALLOC_INFO);
+               c->sb.compat &= ~(1ULL << BCH_COMPAT_alloc_info);
                drop_alloc_keys(&c->journal_keys);
        }
 
+       zero_out_btree_mem_ptr(&c->journal_keys);
+
        ret = journal_replay_early(c, clean, &c->journal_entries);
        if (ret)
                goto err;
@@ -1099,36 +1137,61 @@ use_clean:
 
        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 = bch2_alloc_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 we're not running fsck, this ensures bch2_fsck_err() calls are
+        * instead interpreted as bch2_inconsistent_err() calls:
+        */
+       if (!c->opts.fsck)
+               set_bit(BCH_FS_FSCK_DONE, &c->flags);
 
        if (c->opts.fsck ||
-           !(c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_INFO)) ||
-           !(c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_METADATA)) ||
+           !(c->sb.compat & (1ULL << BCH_COMPAT_alloc_info)) ||
+           !(c->sb.compat & (1ULL << BCH_COMPAT_alloc_metadata)) ||
            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, true);
+               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");
+       }
+
+       if (c->opts.fsck) {
+               bch_info(c, "checking need_discard and freespace btrees");
+               err = "error checking need_discard and freespace btrees";
+               ret = bch2_check_alloc_info(c, true);
+               if (ret)
+                       goto err;
+
+               ret = bch2_check_lrus(c, true);
                if (ret)
                        goto err;
-               bch_verbose(c, "mark and sweep done");
+               bch_verbose(c, "done checking need_discard and freespace btrees");
        }
 
        bch2_stripes_heap_start(c);
 
        clear_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
        set_bit(BCH_FS_INITIAL_GC_DONE, &c->flags);
+       set_bit(BCH_FS_MAY_GO_RW, &c->flags);
 
        /*
         * Skip past versions that might have possibly been used (as nonces),
@@ -1140,48 +1203,42 @@ use_clean:
        if (c->opts.norecovery)
                goto out;
 
-       bch_verbose(c, "starting journal replay");
+       bch_verbose(c, "starting journal replay, %zu keys", c->journal_keys.nr);
        err = "journal replay failed";
-       ret = bch2_journal_replay(c, c->journal_keys);
+       ret = bch2_journal_replay(c);
        if (ret)
                goto err;
-       bch_verbose(c, "journal replay done");
+       if (c->opts.verbose || !c->sb.clean)
+               bch_info(c, "journal replay done");
 
-       if (test_bit(BCH_FS_NEED_ALLOC_WRITE, &c->flags) &&
-           !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");
+       err = "error initializing freespace";
+       ret = bch2_fs_freespace_init(c);
+       if (ret)
+               goto err;
+
+       if (c->sb.version < bcachefs_metadata_version_snapshot_2) {
+               bch2_fs_lazy_rw(c);
+
+               err = "error creating root snapshot node";
+               ret = bch2_fs_initialize_subvolumes(c);
+               if (ret)
                        goto err;
-               }
-               bch_verbose(c, "alloc write 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");
+       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");
 
-               } 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) {
@@ -1191,6 +1248,13 @@ use_clean:
                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)) {
@@ -1203,23 +1267,21 @@ use_clean:
 
        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;
        }
 
@@ -1227,13 +1289,30 @@ use_clean:
                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;
+
+               bch_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);
 
@@ -1247,6 +1326,10 @@ fsck_err:
        else
                bch_verbose(c, "ret %i", ret);
        return ret;
+err:
+fsck_err:
+       bch2_fs_emergency_read_only(c);
+       goto out;
 }
 
 int bch2_fs_initialize(struct bch_fs *c)
@@ -1263,28 +1346,23 @@ int bch2_fs_initialize(struct bch_fs *c)
        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);
-
-       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;
+       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);
 
-       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_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);
-
        err = "unable to allocate journal buckets";
        for_each_online_member(ca, c, i) {
                ret = bch2_dev_journal_alloc(ca);
@@ -1310,18 +1388,45 @@ 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;
 
+       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|S_IRWXU|S_IRUGO|S_IXUGO, 0, NULL);
-       root_inode.bi_inum = BCACHEFS_ROOT_INO;
+       root_inode.bi_inum      = BCACHEFS_ROOT_INO;
+       root_inode.bi_subvol    = BCACHEFS_ROOT_SUBVOL;
        bch2_inode_pack(c, &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)
@@ -1331,13 +1436,16 @@ 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);
@@ -1346,7 +1454,7 @@ 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;