]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/btree_update_interior.c
Update bcachefs sources to 5d0a6c2b32f1 bcachefs: check_directory_structure() can...
[bcachefs-tools-debian] / libbcachefs / btree_update_interior.c
index cf9b9ec4c9d99d4a8d165b3f278e240c93a42023..99e9902fc1e08496af33913dd70625559ce142c3 100644 (file)
@@ -5,42 +5,44 @@
 #include "bkey_methods.h"
 #include "btree_cache.h"
 #include "btree_gc.h"
+#include "btree_journal_iter.h"
 #include "btree_update.h"
 #include "btree_update_interior.h"
 #include "btree_io.h"
 #include "btree_iter.h"
 #include "btree_locking.h"
 #include "buckets.h"
+#include "clock.h"
 #include "error.h"
 #include "extents.h"
 #include "journal.h"
 #include "journal_reclaim.h"
 #include "keylist.h"
-#include "recovery.h"
 #include "replicas.h"
 #include "super-io.h"
+#include "trace.h"
 
 #include <linux/random.h>
-#include <trace/events/bcachefs.h>
 
-static void bch2_btree_insert_node(struct btree_update *, struct btree_trans *,
-                                  struct btree_path *, struct btree *,
-                                  struct keylist *, unsigned);
+static int bch2_btree_insert_node(struct btree_update *, struct btree_trans *,
+                                 btree_path_idx_t, struct btree *,
+                                 struct keylist *, unsigned);
 static void bch2_btree_update_add_new_node(struct btree_update *, struct btree *);
 
-static struct btree_path *get_unlocked_mut_path(struct btree_trans *trans,
-                                               enum btree_id btree_id,
-                                               unsigned level,
-                                               struct bpos pos)
+static btree_path_idx_t get_unlocked_mut_path(struct btree_trans *trans,
+                                             enum btree_id btree_id,
+                                             unsigned level,
+                                             struct bpos pos)
 {
-       struct btree_path *path;
+       btree_path_idx_t path_idx = bch2_path_get(trans, btree_id, pos, level + 1, level,
+                            BTREE_ITER_NOPRESERVE|
+                            BTREE_ITER_INTENT, _RET_IP_);
+       path_idx = bch2_btree_path_make_mut(trans, path_idx, true, _RET_IP_);
 
-       path = bch2_path_get(trans, btree_id, pos, level + 1, level,
-                            BTREE_ITER_INTENT, _THIS_IP_);
-       path = bch2_btree_path_make_mut(trans, path, true, _THIS_IP_);
+       struct btree_path *path = trans->paths + path_idx;
        bch2_btree_path_downgrade(trans, path);
        __bch2_btree_path_unlock(trans, path);
-       return path;
+       return path_idx;
 }
 
 /* Debug code: */
@@ -71,7 +73,7 @@ static void btree_node_interior_verify(struct bch_fs *c, struct btree *b)
                        break;
                bp = bkey_s_c_to_btree_ptr_v2(k);
 
-               if (bpos_cmp(next_node, bp.v->min_key)) {
+               if (!bpos_eq(next_node, bp.v->min_key)) {
                        bch2_dump_btree_node(c, b);
                        bch2_bpos_to_text(&buf1, next_node);
                        bch2_bpos_to_text(&buf2, bp.v->min_key);
@@ -81,7 +83,7 @@ static void btree_node_interior_verify(struct bch_fs *c, struct btree *b)
                bch2_btree_node_iter_advance(&iter, b);
 
                if (bch2_btree_node_iter_end(&iter)) {
-                       if (bpos_cmp(k.k->p, b->key.k.p)) {
+                       if (!bpos_eq(k.k->p, b->key.k.p)) {
                                bch2_dump_btree_node(c, b);
                                bch2_bpos_to_text(&buf1, b->key.k.p);
                                bch2_bpos_to_text(&buf2, k.k->p);
@@ -97,7 +99,7 @@ static void btree_node_interior_verify(struct bch_fs *c, struct btree *b)
 
 /* Calculate ideal packed bkey format for new btree nodes: */
 
-void __bch2_btree_calc_format(struct bkey_format_state *s, struct btree *b)
+static void __bch2_btree_calc_format(struct bkey_format_state *s, struct btree *b)
 {
        struct bkey_packed *k;
        struct bset_tree *t;
@@ -123,43 +125,52 @@ static struct bkey_format bch2_btree_calc_format(struct btree *b)
        return bch2_bkey_format_done(&s);
 }
 
-static size_t btree_node_u64s_with_format(struct btree *b,
+static size_t btree_node_u64s_with_format(struct btree_nr_keys nr,
+                                         struct bkey_format *old_f,
                                          struct bkey_format *new_f)
 {
-       struct bkey_format *old_f = &b->format;
-
        /* stupid integer promotion rules */
        ssize_t delta =
            (((int) new_f->key_u64s - old_f->key_u64s) *
-            (int) b->nr.packed_keys) +
+            (int) nr.packed_keys) +
            (((int) new_f->key_u64s - BKEY_U64s) *
-            (int) b->nr.unpacked_keys);
+            (int) nr.unpacked_keys);
 
-       BUG_ON(delta + b->nr.live_u64s < 0);
+       BUG_ON(delta + nr.live_u64s < 0);
 
-       return b->nr.live_u64s + delta;
+       return nr.live_u64s + delta;
 }
 
 /**
- * btree_node_format_fits - check if we could rewrite node with a new format
+ * bch2_btree_node_format_fits - check if we could rewrite node with a new format
+ *
+ * @c:         filesystem handle
+ * @b:         btree node to rewrite
+ * @nr:                number of keys for new node (i.e. b->nr)
+ * @new_f:     bkey format to translate keys to
  *
- * This assumes all keys can pack with the new format -- it just checks if
- * the re-packed keys would fit inside the node itself.
+ * Returns: true if all re-packed keys will be able to fit in a new node.
+ *
+ * Assumes all keys will successfully pack with the new format.
  */
-bool bch2_btree_node_format_fits(struct bch_fs *c, struct btree *b,
+static bool bch2_btree_node_format_fits(struct bch_fs *c, struct btree *b,
+                                struct btree_nr_keys nr,
                                 struct bkey_format *new_f)
 {
-       size_t u64s = btree_node_u64s_with_format(b, new_f);
+       size_t u64s = btree_node_u64s_with_format(nr, &b->format, new_f);
 
        return __vstruct_bytes(struct btree_node, u64s) < btree_bytes(c);
 }
 
 /* Btree node freeing/allocation: */
 
-static void __btree_node_free(struct bch_fs *c, struct btree *b)
+static void __btree_node_free(struct btree_trans *trans, struct btree *b)
 {
-       trace_and_count(c, btree_node_free, c, b);
+       struct bch_fs *c = trans->c;
 
+       trace_and_count(c, btree_node_free, trans, b);
+
+       BUG_ON(btree_node_write_blocked(b));
        BUG_ON(btree_node_dirty(b));
        BUG_ON(btree_node_need_write(b));
        BUG_ON(b == btree_node_root(c, b));
@@ -179,15 +190,52 @@ static void bch2_btree_node_free_inmem(struct btree_trans *trans,
                                       struct btree *b)
 {
        struct bch_fs *c = trans->c;
-       unsigned level = b->c.level;
+       unsigned i, level = b->c.level;
 
        bch2_btree_node_lock_write_nofail(trans, path, &b->c);
        bch2_btree_node_hash_remove(&c->btree_cache, b);
-       __btree_node_free(c, b);
+       __btree_node_free(trans, b);
        six_unlock_write(&b->c.lock);
-       mark_btree_node_locked_noreset(path, level, SIX_LOCK_intent);
+       mark_btree_node_locked_noreset(path, level, BTREE_NODE_INTENT_LOCKED);
 
-       trans_for_each_path(trans, path)
+       trans_for_each_path(trans, path, i)
+               if (path->l[level].b == b) {
+                       btree_node_unlock(trans, path, level);
+                       path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
+               }
+}
+
+static void bch2_btree_node_free_never_used(struct btree_update *as,
+                                           struct btree_trans *trans,
+                                           struct btree *b)
+{
+       struct bch_fs *c = as->c;
+       struct prealloc_nodes *p = &as->prealloc_nodes[b->c.lock.readers != NULL];
+       struct btree_path *path;
+       unsigned i, level = b->c.level;
+
+       BUG_ON(!list_empty(&b->write_blocked));
+       BUG_ON(b->will_make_reachable != (1UL|(unsigned long) as));
+
+       b->will_make_reachable = 0;
+       closure_put(&as->cl);
+
+       clear_btree_node_will_make_reachable(b);
+       clear_btree_node_accessed(b);
+       clear_btree_node_dirty_acct(c, b);
+       clear_btree_node_need_write(b);
+
+       mutex_lock(&c->btree_cache.lock);
+       list_del_init(&b->list);
+       bch2_btree_node_hash_remove(&c->btree_cache, b);
+       mutex_unlock(&c->btree_cache.lock);
+
+       BUG_ON(p->nr >= ARRAY_SIZE(p->b));
+       p->b[p->nr++] = b;
+
+       six_unlock_intent(&b->c.lock);
+
+       trans_for_each_path(trans, path, i)
                if (path->l[level].b == b) {
                        btree_node_unlock(trans, path, level);
                        path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
@@ -203,26 +251,21 @@ static struct btree *__bch2_btree_node_alloc(struct btree_trans *trans,
        struct bch_fs *c = trans->c;
        struct write_point *wp;
        struct btree *b;
-       __BKEY_PADDED(k, BKEY_BTREE_PTR_VAL_U64s_MAX) tmp;
-       struct open_buckets ob = { .nr = 0 };
+       BKEY_PADDED_ONSTACK(k, BKEY_BTREE_PTR_VAL_U64s_MAX) tmp;
+       struct open_buckets obs = { .nr = 0 };
        struct bch_devs_list devs_have = (struct bch_devs_list) { 0 };
-       unsigned nr_reserve;
-       enum alloc_reserve alloc_reserve;
-
-       if (flags & BTREE_INSERT_USE_RESERVE) {
-               nr_reserve      = 0;
-               alloc_reserve   = RESERVE_btree_movinggc;
-       } else {
-               nr_reserve      = BTREE_NODE_RESERVE;
-               alloc_reserve   = RESERVE_btree;
-       }
+       enum bch_watermark watermark = flags & BCH_WATERMARK_MASK;
+       unsigned nr_reserve = watermark > BCH_WATERMARK_reclaim
+               ? BTREE_NODE_RESERVE
+               : 0;
+       int ret;
 
        mutex_lock(&c->btree_reserve_cache_lock);
        if (c->btree_reserve_cache_nr > nr_reserve) {
                struct btree_alloc *a =
                        &c->btree_reserve_cache[--c->btree_reserve_cache_nr];
 
-               ob = a->ob;
+               obs = a->ob;
                bkey_copy(&tmp.k, &a->k);
                mutex_unlock(&c->btree_reserve_cache_lock);
                goto mem_alloc;
@@ -230,7 +273,7 @@ static struct btree *__bch2_btree_node_alloc(struct btree_trans *trans,
        mutex_unlock(&c->btree_reserve_cache_lock);
 
 retry:
-       wp = bch2_alloc_sectors_start_trans(trans,
+       ret = bch2_alloc_sectors_start_trans(trans,
                                      c->opts.metadata_target ?:
                                      c->opts.foreground_target,
                                      0,
@@ -238,9 +281,9 @@ retry:
                                      &devs_have,
                                      res->nr_replicas,
                                      c->opts.metadata_replicas_required,
-                                     alloc_reserve, 0, cl);
-       if (IS_ERR(wp))
-               return ERR_CAST(wp);
+                                     watermark, 0, cl, &wp);
+       if (unlikely(ret))
+               return ERR_PTR(ret);
 
        if (wp->sectors_free < btree_sectors(c)) {
                struct open_bucket *ob;
@@ -257,10 +300,10 @@ retry:
        bkey_btree_ptr_v2_init(&tmp.k);
        bch2_alloc_sectors_append_ptrs(c, wp, &tmp.k, btree_sectors(c), false);
 
-       bch2_open_bucket_get(c, wp, &ob);
+       bch2_open_bucket_get(c, wp, &obs);
        bch2_alloc_sectors_done(c, wp);
 mem_alloc:
-       b = bch2_btree_node_mem_alloc(c, interior_node);
+       b = bch2_btree_node_mem_alloc(trans, interior_node);
        six_unlock_write(&b->c.lock);
        six_unlock_intent(&b->c.lock);
 
@@ -269,7 +312,7 @@ mem_alloc:
        BUG_ON(b->ob.nr);
 
        bkey_copy(&b->key, &tmp.k);
-       b->ob = ob;
+       b->ob = obs;
 
        return b;
 }
@@ -322,7 +365,8 @@ static struct btree *bch2_btree_node_alloc(struct btree_update *as,
        ret = bch2_btree_node_hash_insert(&c->btree_cache, b, level, as->btree_id);
        BUG_ON(ret);
 
-       trace_and_count(c, btree_node_alloc, c, b);
+       trace_and_count(c, btree_node_alloc, trans, b);
+       bch2_increment_clock(c, btree_sectors(c), WRITE);
        return b;
 }
 
@@ -339,14 +383,19 @@ static void btree_set_max(struct btree *b, struct bpos pos)
        b->data->max_key = pos;
 }
 
-struct btree *__bch2_btree_node_alloc_replacement(struct btree_update *as,
-                                                 struct btree_trans *trans,
-                                                 struct btree *b,
-                                                 struct bkey_format format)
+static struct btree *bch2_btree_node_alloc_replacement(struct btree_update *as,
+                                                      struct btree_trans *trans,
+                                                      struct btree *b)
 {
-       struct btree *n;
+       struct btree *n = bch2_btree_node_alloc(as, trans, b->c.level);
+       struct bkey_format format = bch2_btree_calc_format(b);
 
-       n = bch2_btree_node_alloc(as, trans, b->c.level);
+       /*
+        * The keys might expand with the new format - if they wouldn't fit in
+        * the btree node anymore, use the old format for now:
+        */
+       if (!bch2_btree_node_format_fits(as->c, b, b->nr, &format))
+               format = b->format;
 
        SET_BTREE_NODE_SEQ(n->data, BTREE_NODE_SEQ(b->data) + 1);
 
@@ -359,27 +408,9 @@ struct btree *__bch2_btree_node_alloc_replacement(struct btree_update *as,
        bch2_btree_sort_into(as->c, n, b);
 
        btree_node_reset_sib_u64s(n);
-
-       n->key.k.p = b->key.k.p;
        return n;
 }
 
-static struct btree *bch2_btree_node_alloc_replacement(struct btree_update *as,
-                                                      struct btree_trans *trans,
-                                                      struct btree *b)
-{
-       struct bkey_format new_f = bch2_btree_calc_format(b);
-
-       /*
-        * The keys might expand with the new format - if they wouldn't fit in
-        * the btree node anymore, use the old format for now:
-        */
-       if (!bch2_btree_node_format_fits(as->c, b, &new_f))
-               new_f = b->format;
-
-       return __bch2_btree_node_alloc_replacement(as, trans, b, new_f);
-}
-
 static struct btree *__btree_root_alloc(struct btree_update *as,
                                struct btree_trans *trans, unsigned level)
 {
@@ -392,9 +423,6 @@ static struct btree *__btree_root_alloc(struct btree_update *as,
        btree_node_set_format(b, b->data->format);
        bch2_btree_build_aux_trees(b);
 
-       bch2_btree_update_add_new_node(as, b);
-       six_unlock_write(&b->c.lock);
-
        return b;
 }
 
@@ -427,7 +455,7 @@ static void bch2_btree_reserve_put(struct btree_update *as, struct btree_trans *
 
                        btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
                        btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
-                       __btree_node_free(c, b);
+                       __btree_node_free(trans, b);
                        six_unlock_write(&b->c.lock);
                        six_unlock_intent(&b->c.lock);
                }
@@ -440,7 +468,6 @@ static int bch2_btree_reserve_get(struct btree_trans *trans,
                                  unsigned flags,
                                  struct closure *cl)
 {
-       struct bch_fs *c = as->c;
        struct btree *b;
        unsigned interior;
        int ret = 0;
@@ -450,11 +477,8 @@ static int bch2_btree_reserve_get(struct btree_trans *trans,
        /*
         * Protects reaping from the btree node cache and using the btree node
         * open bucket reserve:
-        *
-        * BTREE_INSERT_NOWAIT only applies to btree node allocation, not
-        * blocking on this lock:
         */
-       ret = bch2_btree_cache_cannibalize_lock(c, cl);
+       ret = bch2_btree_cache_cannibalize_lock(trans, cl);
        if (ret)
                return ret;
 
@@ -462,9 +486,8 @@ static int bch2_btree_reserve_get(struct btree_trans *trans,
                struct prealloc_nodes *p = as->prealloc_nodes + interior;
 
                while (p->nr < nr_nodes[interior]) {
-                       b = __bch2_btree_node_alloc(trans, &as->disk_res,
-                                       flags & BTREE_INSERT_NOWAIT ? NULL : cl,
-                                       interior, flags);
+                       b = __bch2_btree_node_alloc(trans, &as->disk_res, cl,
+                                                   interior, flags);
                        if (IS_ERR(b)) {
                                ret = PTR_ERR(b);
                                goto err;
@@ -474,7 +497,7 @@ static int bch2_btree_reserve_get(struct btree_trans *trans,
                }
        }
 err:
-       bch2_btree_cache_cannibalize_unlock(c);
+       bch2_btree_cache_cannibalize_unlock(trans);
        return ret;
 }
 
@@ -488,8 +511,6 @@ static void bch2_btree_update_free(struct btree_update *as, struct btree_trans *
                up_read(&c->gc_lock);
        as->took_gc_lock = false;
 
-       bch2_journal_preres_put(&c->journal, &as->journal_preres);
-
        bch2_journal_pin_drop(&c->journal, &as->journal);
        bch2_journal_pin_flush(&c->journal, &as->journal);
        bch2_disk_reservation_put(c, &as->disk_res);
@@ -536,16 +557,13 @@ static int btree_update_nodes_written_trans(struct btree_trans *trans,
                                            struct btree_update *as)
 {
        struct bkey_i *k;
-       int ret;
 
-       ret = darray_make_room(&trans->extra_journal_entries, as->journal_u64s);
+       struct jset_entry *e = bch2_trans_jset_entry_alloc(trans, as->journal_u64s);
+       int ret = PTR_ERR_OR_ZERO(e);
        if (ret)
                return ret;
 
-       memcpy(&darray_top(trans->extra_journal_entries),
-              as->journal_entries,
-              as->journal_u64s * sizeof(u64));
-       trans->extra_journal_entries.nr += as->journal_u64s;
+       memcpy(e, as->journal_entries, as->journal_u64s * sizeof(u64));
 
        trans->journal_pin = &as->journal;
 
@@ -572,12 +590,11 @@ static void btree_update_nodes_written(struct btree_update *as)
 {
        struct bch_fs *c = as->c;
        struct btree *b;
-       struct btree_trans trans;
+       struct btree_trans *trans = bch2_trans_get(c);
        u64 journal_seq = 0;
        unsigned i;
        int ret;
 
-       bch2_trans_init(&trans, c, 0, 512);
        /*
         * If we're already in an error state, it might be because a btree node
         * was never written, and we might be trying to free that same btree
@@ -598,7 +615,7 @@ static void btree_update_nodes_written(struct btree_update *as)
 
                b = as->old_nodes[i];
 
-               btree_node_lock_nopath_nofail(&trans, &b->c, SIX_LOCK_read);
+               btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read);
                seq = b->data ? b->data->keys.seq : 0;
                six_unlock_read(&b->c.lock);
 
@@ -620,23 +637,23 @@ static void btree_update_nodes_written(struct btree_update *as)
         * journal reclaim does btree updates when flushing bkey_cached entries,
         * which may require allocations as well.
         */
-       ret = commit_do(&trans, &as->disk_res, &journal_seq,
-                       BTREE_INSERT_NOFAIL|
-                       BTREE_INSERT_NOCHECK_RW|
-                       BTREE_INSERT_USE_RESERVE|
-                       BTREE_INSERT_JOURNAL_RECLAIM|
-                       JOURNAL_WATERMARK_reserved,
-                       btree_update_nodes_written_trans(&trans, as));
-       bch2_trans_unlock(&trans);
+       ret = commit_do(trans, &as->disk_res, &journal_seq,
+                       BCH_WATERMARK_reclaim|
+                       BCH_TRANS_COMMIT_no_enospc|
+                       BCH_TRANS_COMMIT_no_check_rw|
+                       BCH_TRANS_COMMIT_journal_reclaim,
+                       btree_update_nodes_written_trans(trans, as));
+       bch2_trans_unlock(trans);
 
        bch2_fs_fatal_err_on(ret && !bch2_journal_error(&c->journal), c,
-                            "error %i in btree_update_nodes_written()", ret);
+                            "%s(): error %s", __func__, bch2_err_str(ret));
 err:
        if (as->b) {
-               struct btree_path *path;
 
                b = as->b;
-               path = get_unlocked_mut_path(&trans, as->btree_id, b->c.level, b->key.k.p);
+               btree_path_idx_t path_idx = get_unlocked_mut_path(trans,
+                                               as->btree_id, b->c.level, b->key.k.p);
+               struct btree_path *path = trans->paths + path_idx;
                /*
                 * @b is the node we did the final insert into:
                 *
@@ -649,11 +666,23 @@ err:
                 * we're in journal error state:
                 */
 
-               btree_node_lock_nopath_nofail(&trans, &b->c, SIX_LOCK_intent);
-               mark_btree_node_locked(&trans, path, b->c.level, SIX_LOCK_intent);
-               bch2_btree_path_level_init(&trans, path, b);
+               /*
+                * Ensure transaction is unlocked before using
+                * btree_node_lock_nopath() (the use of which is always suspect,
+                * we need to work on removing this in the future)
+                *
+                * It should be, but get_unlocked_mut_path() -> bch2_path_get()
+                * calls bch2_path_upgrade(), before we call path_make_mut(), so
+                * we may rarely end up with a locked path besides the one we
+                * have here:
+                */
+               bch2_trans_unlock(trans);
+               btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
+               mark_btree_node_locked(trans, path, b->c.level, BTREE_NODE_INTENT_LOCKED);
+               path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
+               path->l[b->c.level].b = b;
 
-               bch2_btree_node_lock_write_nofail(&trans, path, &b->c);
+               bch2_btree_node_lock_write_nofail(trans, path, &b->c);
 
                mutex_lock(&c->btree_interior_update_lock);
 
@@ -666,15 +695,15 @@ err:
                 * btree_interior_update_lock:
                 */
                if (as->b == b) {
-                       struct bset *i = btree_bset_last(b);
-
                        BUG_ON(!b->c.level);
                        BUG_ON(!btree_node_dirty(b));
 
                        if (!ret) {
-                               i->journal_seq = cpu_to_le64(
+                               struct bset *last = btree_bset_last(b);
+
+                               last->journal_seq = cpu_to_le64(
                                                             max(journal_seq,
-                                                                le64_to_cpu(i->journal_seq)));
+                                                                le64_to_cpu(last->journal_seq)));
 
                                bch2_btree_add_journal_pin(c, b, journal_seq);
                        } else {
@@ -689,18 +718,16 @@ err:
 
                mutex_unlock(&c->btree_interior_update_lock);
 
-               mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_intent);
+               mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED);
                six_unlock_write(&b->c.lock);
 
                btree_node_write_if_need(c, b, SIX_LOCK_intent);
-               btree_node_unlock(&trans, path, b->c.level);
-               bch2_path_put(&trans, path, true);
+               btree_node_unlock(trans, path, b->c.level);
+               bch2_path_put(trans, path_idx, true);
        }
 
        bch2_journal_pin_drop(&c->journal, &as->journal);
 
-       bch2_journal_preres_put(&c->journal, &as->journal_preres);
-
        mutex_lock(&c->btree_interior_update_lock);
        for (i = 0; i < as->nr_new_nodes; i++) {
                b = as->new_nodes[i];
@@ -714,7 +741,7 @@ err:
        for (i = 0; i < as->nr_new_nodes; i++) {
                b = as->new_nodes[i];
 
-               btree_node_lock_nopath_nofail(&trans, &b->c, SIX_LOCK_read);
+               btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read);
                btree_node_write_if_need(c, b, SIX_LOCK_read);
                six_unlock_read(&b->c.lock);
        }
@@ -722,8 +749,8 @@ err:
        for (i = 0; i < as->nr_open_buckets; i++)
                bch2_open_bucket_put(c, c->open_buckets + as->open_buckets[i]);
 
-       bch2_btree_update_free(as, &trans);
-       bch2_trans_exit(&trans);
+       bch2_btree_update_free(as, trans);
+       bch2_trans_put(trans);
 }
 
 static void btree_interior_update_work(struct work_struct *work)
@@ -747,9 +774,9 @@ static void btree_interior_update_work(struct work_struct *work)
        }
 }
 
-static void btree_update_set_nodes_written(struct closure *cl)
+static CLOSURE_CALLBACK(btree_update_set_nodes_written)
 {
-       struct btree_update *as = container_of(cl, struct btree_update, cl);
+       closure_type(as, struct btree_update, cl);
        struct bch_fs *c = as->c;
 
        mutex_lock(&c->btree_interior_update_lock);
@@ -772,6 +799,7 @@ static void btree_update_updated_node(struct btree_update *as, struct btree *b)
 
        BUG_ON(as->mode != BTREE_INTERIOR_NO_UPDATE);
        BUG_ON(!btree_node_dirty(b));
+       BUG_ON(!b->c.level);
 
        as->mode        = BTREE_INTERIOR_UPDATING_NODE;
        as->b           = b;
@@ -782,6 +810,12 @@ static void btree_update_updated_node(struct btree_update *as, struct btree *b)
        mutex_unlock(&c->btree_interior_update_lock);
 }
 
+static int bch2_update_reparent_journal_pin_flush(struct journal *j,
+                               struct journal_entry_pin *_pin, u64 seq)
+{
+       return 0;
+}
+
 static void btree_update_reparent(struct btree_update *as,
                                  struct btree_update *child)
 {
@@ -792,7 +826,8 @@ static void btree_update_reparent(struct btree_update *as,
        child->b = NULL;
        child->mode = BTREE_INTERIOR_UPDATING_AS;
 
-       bch2_journal_pin_copy(&c->journal, &as->journal, &child->journal, NULL);
+       bch2_journal_pin_copy(&c->journal, &as->journal, &child->journal,
+                             bch2_update_reparent_journal_pin_flush);
 }
 
 static void btree_update_updated_root(struct btree_update *as, struct btree *b)
@@ -847,6 +882,14 @@ static void bch2_btree_update_add_new_node(struct btree_update *as, struct btree
        mutex_unlock(&c->btree_interior_update_lock);
 
        btree_update_add_key(as, &as->new_keys, b);
+
+       if (b->key.k.type == KEY_TYPE_btree_ptr_v2) {
+               unsigned bytes = vstruct_end(&b->data->keys) - (void *) b->data;
+               unsigned sectors = round_up(bytes, block_bytes(c)) >> 9;
+
+               bkey_i_to_btree_ptr_v2(&b->key)->v.sectors_written =
+                       cpu_to_le16(sectors);
+       }
 }
 
 /*
@@ -893,6 +936,12 @@ static void bch2_btree_update_get_open_buckets(struct btree_update *as, struct b
                        b->ob.v[--b->ob.nr];
 }
 
+static int bch2_btree_update_will_free_node_journal_pin_flush(struct journal *j,
+                               struct journal_entry_pin *_pin, u64 seq)
+{
+       return 0;
+}
+
 /*
  * @b is being split/rewritten: it may have pointers to not-yet-written btree
  * nodes and thus outstanding btree_updates - redirect @b's
@@ -933,6 +982,7 @@ static void bch2_btree_interior_update_will_free_node(struct btree_update *as,
 
        clear_btree_node_dirty_acct(c, b);
        clear_btree_node_need_write(b);
+       clear_btree_node_write_blocked(b);
 
        /*
         * Does this node have unwritten data that has a pin on the journal?
@@ -943,11 +993,13 @@ static void bch2_btree_interior_update_will_free_node(struct btree_update *as,
         * when the new nodes are persistent and reachable on disk:
         */
        w = btree_current_write(b);
-       bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal, NULL);
+       bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal,
+                             bch2_btree_update_will_free_node_journal_pin_flush);
        bch2_journal_pin_drop(&c->journal, &w->journal);
 
        w = btree_prev_write(b);
-       bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal, NULL);
+       bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal,
+                             bch2_btree_update_will_free_node_journal_pin_flush);
        bch2_journal_pin_drop(&c->journal, &w->journal);
 
        mutex_unlock(&c->btree_interior_update_lock);
@@ -997,61 +1049,78 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
        struct bch_fs *c = trans->c;
        struct btree_update *as;
        u64 start_time = local_clock();
-       int disk_res_flags = (flags & BTREE_INSERT_NOFAIL)
+       int disk_res_flags = (flags & BCH_TRANS_COMMIT_no_enospc)
                ? BCH_DISK_RESERVATION_NOFAIL : 0;
        unsigned nr_nodes[2] = { 0, 0 };
        unsigned update_level = level;
-       int journal_flags = flags & JOURNAL_WATERMARK_MASK;
+       enum bch_watermark watermark = flags & BCH_WATERMARK_MASK;
        int ret = 0;
        u32 restart_count = trans->restart_count;
 
        BUG_ON(!path->should_be_locked);
 
-       if (flags & BTREE_INSERT_JOURNAL_RECLAIM)
-               journal_flags |= JOURNAL_RES_GET_NONBLOCK;
+       if (watermark == BCH_WATERMARK_copygc)
+               watermark = BCH_WATERMARK_btree_copygc;
+       if (watermark < BCH_WATERMARK_btree)
+               watermark = BCH_WATERMARK_btree;
+
+       flags &= ~BCH_WATERMARK_MASK;
+       flags |= watermark;
+
+       if (!(flags & BCH_TRANS_COMMIT_journal_reclaim) &&
+           watermark < c->journal.watermark) {
+               struct journal_res res = { 0 };
+
+               ret = drop_locks_do(trans,
+                       bch2_journal_res_get(&c->journal, &res, 1,
+                                            watermark|JOURNAL_RES_GET_CHECK));
+               if (ret)
+                       return ERR_PTR(ret);
+       }
 
        while (1) {
                nr_nodes[!!update_level] += 1 + split;
                update_level++;
 
-               if (!btree_path_node(path, update_level))
+               ret = bch2_btree_path_upgrade(trans, path, update_level + 1);
+               if (ret)
+                       return ERR_PTR(ret);
+
+               if (!btree_path_node(path, update_level)) {
+                       /* Allocating new root? */
+                       nr_nodes[1] += split;
+                       update_level = BTREE_MAX_DEPTH;
                        break;
+               }
 
                /*
-                * XXX: figure out how far we might need to split,
-                * instead of locking/reserving all the way to the root:
+                * Always check for space for two keys, even if we won't have to
+                * split at prior level - it might have been a merge instead:
                 */
-               split = update_level + 1 < BTREE_MAX_DEPTH;
-       }
-
-       /* Might have to allocate a new root: */
-       if (update_level < BTREE_MAX_DEPTH)
-               nr_nodes[1] += 1;
+               if (bch2_btree_node_insert_fits(c, path->l[update_level].b,
+                                               BKEY_BTREE_PTR_U64s_MAX * 2))
+                       break;
 
-       ret = bch2_btree_path_upgrade(trans, path, U8_MAX);
-       if (ret)
-               return ERR_PTR(ret);
+               split = path->l[update_level].b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c);
+       }
 
-       if (flags & BTREE_INSERT_GC_LOCK_HELD)
-               lockdep_assert_held(&c->gc_lock);
-       else if (!down_read_trylock(&c->gc_lock)) {
-               bch2_trans_unlock(trans);
-               down_read(&c->gc_lock);
-               ret = bch2_trans_relock(trans);
+       if (!down_read_trylock(&c->gc_lock)) {
+               ret = drop_locks_do(trans, (down_read(&c->gc_lock), 0));
                if (ret) {
                        up_read(&c->gc_lock);
                        return ERR_PTR(ret);
                }
        }
 
-       as = mempool_alloc(&c->btree_interior_update_pool, GFP_NOIO);
+       as = mempool_alloc(&c->btree_interior_update_pool, GFP_NOFS);
        memset(as, 0, sizeof(*as));
        closure_init(&as->cl, NULL);
        as->c           = c;
        as->start_time  = start_time;
        as->mode        = BTREE_INTERIOR_NO_UPDATE;
-       as->took_gc_lock = !(flags & BTREE_INSERT_GC_LOCK_HELD);
+       as->took_gc_lock = true;
        as->btree_id    = path->btree_id;
+       as->update_level = update_level;
        INIT_LIST_HEAD(&as->list);
        INIT_LIST_HEAD(&as->unwritten_list);
        INIT_LIST_HEAD(&as->write_blocked_list);
@@ -1075,31 +1144,6 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
        if (ret)
                goto err;
 
-       ret = bch2_journal_preres_get(&c->journal, &as->journal_preres,
-                                     BTREE_UPDATE_JOURNAL_RES,
-                                     journal_flags|JOURNAL_RES_GET_NONBLOCK);
-       if (ret) {
-               bch2_trans_unlock(trans);
-
-               if (flags & BTREE_INSERT_JOURNAL_RECLAIM) {
-                       ret = -BCH_ERR_journal_reclaim_would_deadlock;
-                       goto err;
-               }
-
-               ret = bch2_journal_preres_get(&c->journal, &as->journal_preres,
-                                             BTREE_UPDATE_JOURNAL_RES,
-                                             journal_flags);
-               if (ret) {
-                       trace_and_count(c, trans_restart_journal_preres_get, trans, _RET_IP_, journal_flags);
-                       ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_journal_preres_get);
-                       goto err;
-               }
-
-               ret = bch2_trans_relock(trans);
-               if (ret)
-                       goto err;
-       }
-
        ret = bch2_disk_reservation_get(c, &as->disk_res,
                        (nr_nodes[0] + nr_nodes[1]) * btree_sectors(c),
                        c->opts.metadata_replicas,
@@ -1112,6 +1156,17 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
            bch2_err_matches(ret, ENOMEM)) {
                struct closure cl;
 
+               /*
+                * XXX: this should probably be a separate BTREE_INSERT_NONBLOCK
+                * flag
+                */
+               if (bch2_err_matches(ret, ENOSPC) &&
+                   (flags & BCH_TRANS_COMMIT_journal_reclaim) &&
+                   watermark != BCH_WATERMARK_reclaim) {
+                       ret = -BCH_ERR_journal_reclaim_would_deadlock;
+                       goto err;
+               }
+
                closure_init_stack(&cl);
 
                do {
@@ -1119,11 +1174,12 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
 
                        bch2_trans_unlock(trans);
                        closure_sync(&cl);
-               } while (ret == -EAGAIN);
+               } while (bch2_err_matches(ret, BCH_ERR_operation_blocked));
        }
 
        if (ret) {
-               trace_and_count(c, btree_reserve_get_fail, trans->fn, _RET_IP_, nr_nodes[0] + nr_nodes[1]);
+               trace_and_count(c, btree_reserve_get_fail, trans->fn,
+                               _RET_IP_, nr_nodes[0] + nr_nodes[1], ret);
                goto err;
        }
 
@@ -1135,6 +1191,9 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
        return as;
 err:
        bch2_btree_update_free(as, trans);
+       if (!bch2_err_matches(ret, ENOSPC) &&
+           !bch2_err_matches(ret, EROFS))
+               bch_err_fn_ratelimited(c, ret);
        return ERR_PTR(ret);
 }
 
@@ -1152,24 +1211,12 @@ static void bch2_btree_set_root_inmem(struct bch_fs *c, struct btree *b)
               (b->c.level < btree_node_root(c, b)->c.level ||
                !btree_node_dying(btree_node_root(c, b))));
 
-       btree_node_root(c, b) = b;
+       bch2_btree_id_root(c, b->c.btree_id)->b = b;
        mutex_unlock(&c->btree_root_lock);
 
        bch2_recalc_btree_reserve(c);
 }
 
-/**
- * bch_btree_set_root - update the root in memory and on disk
- *
- * To ensure forward progress, the current task must not be holding any
- * btree node write locks. However, you must hold an intent lock on the
- * old root.
- *
- * Note: This allocates a journal entry but doesn't add any keys to
- * it.  All the btree roots are part of every journal write, so there
- * is nothing new to be done.  This just guarantees that there is a
- * journal write.
- */
 static void bch2_btree_set_root(struct btree_update *as,
                                struct btree_trans *trans,
                                struct btree_path *path,
@@ -1178,8 +1225,7 @@ static void bch2_btree_set_root(struct btree_update *as,
        struct bch_fs *c = as->c;
        struct btree *old;
 
-       trace_and_count(c, btree_node_set_root, c, b);
-       BUG_ON(!b->written);
+       trace_and_count(c, btree_node_set_root, trans, b);
 
        old = btree_node_root(c, b);
 
@@ -1215,6 +1261,7 @@ static void bch2_insert_fixup_btree_ptr(struct btree_update *as,
        struct bch_fs *c = as->c;
        struct bkey_packed *k;
        struct printbuf buf = PRINTBUF;
+       unsigned long old, new, v;
 
        BUG_ON(insert->k.type == KEY_TYPE_btree_ptr_v2 &&
               !btree_ptr_sectors_written(insert));
@@ -1224,14 +1271,14 @@ static void bch2_insert_fixup_btree_ptr(struct btree_update *as,
 
        if (bch2_bkey_invalid(c, bkey_i_to_s_c(insert),
                              btree_node_type(b), WRITE, &buf) ?:
-           bch2_bkey_in_btree_node(b, bkey_i_to_s_c(insert), &buf)) {
+           bch2_bkey_in_btree_node(c, b, bkey_i_to_s_c(insert), &buf)) {
                printbuf_reset(&buf);
                prt_printf(&buf, "inserting invalid bkey\n  ");
                bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(insert));
                prt_printf(&buf, "\n  ");
                bch2_bkey_invalid(c, bkey_i_to_s_c(insert),
                                  btree_node_type(b), WRITE, &buf);
-               bch2_bkey_in_btree_node(b, bkey_i_to_s_c(insert), &buf);
+               bch2_bkey_in_btree_node(c, b, bkey_i_to_s_c(insert), &buf);
 
                bch2_fs_inconsistent(c, "%s", buf.buf);
                dump_stack();
@@ -1252,7 +1299,15 @@ static void bch2_insert_fixup_btree_ptr(struct btree_update *as,
 
        bch2_btree_bset_insert_key(trans, path, b, node_iter, insert);
        set_btree_node_dirty_acct(c, b);
-       set_btree_node_need_write(b);
+
+       v = READ_ONCE(b->flags);
+       do {
+               old = new = v;
+
+               new &= ~BTREE_WRITE_TYPE_MASK;
+               new |= BTREE_WRITE_interior;
+               new |= 1 << BTREE_NODE_need_write;
+       } while ((v = cmpxchg(&b->flags, old, new)) != old);
 
        printbuf_exit(&buf);
 }
@@ -1275,8 +1330,12 @@ __bch2_btree_insert_keys_interior(struct btree_update *as,
                ;
 
        while (!bch2_keylist_empty(keys)) {
-               bch2_insert_fixup_btree_ptr(as, trans, path, b,
-                               &node_iter, bch2_keylist_front(keys));
+               insert = bch2_keylist_front(keys);
+
+               if (bpos_gt(insert->k.p, b->key.k.p))
+                       break;
+
+               bch2_insert_fixup_btree_ptr(as, trans, path, b, &node_iter, insert);
                bch2_keylist_pop_front(keys);
        }
 }
@@ -1285,111 +1344,103 @@ __bch2_btree_insert_keys_interior(struct btree_update *as,
  * Move keys from n1 (original replacement node, now lower node) to n2 (higher
  * node)
  */
-static struct btree *__btree_split_node(struct btree_update *as,
-                                       struct btree_trans *trans,
-                                       struct btree *n1)
+static void __btree_split_node(struct btree_update *as,
+                              struct btree_trans *trans,
+                              struct btree *b,
+                              struct btree *n[2])
 {
-       struct bkey_format_state s;
-       size_t nr_packed = 0, nr_unpacked = 0;
-       struct btree *n2;
-       struct bset *set1, *set2;
-       struct bkey_packed *k, *set2_start, *set2_end, *out, *prev = NULL;
-       struct bpos n1_pos;
-
-       n2 = bch2_btree_node_alloc(as, trans, n1->c.level);
+       struct bkey_packed *k;
+       struct bpos n1_pos = POS_MIN;
+       struct btree_node_iter iter;
+       struct bset *bsets[2];
+       struct bkey_format_state format[2];
+       struct bkey_packed *out[2];
+       struct bkey uk;
+       unsigned u64s, n1_u64s = (b->nr.live_u64s * 3) / 5;
+       struct { unsigned nr_keys, val_u64s; } nr_keys[2];
+       int i;
 
-       n2->data->max_key       = n1->data->max_key;
-       n2->data->format        = n1->format;
-       SET_BTREE_NODE_SEQ(n2->data, BTREE_NODE_SEQ(n1->data));
-       n2->key.k.p = n1->key.k.p;
+       memset(&nr_keys, 0, sizeof(nr_keys));
 
-       bch2_btree_update_add_new_node(as, n2);
+       for (i = 0; i < 2; i++) {
+               BUG_ON(n[i]->nsets != 1);
 
-       set1 = btree_bset_first(n1);
-       set2 = btree_bset_first(n2);
+               bsets[i] = btree_bset_first(n[i]);
+               out[i] = bsets[i]->start;
 
-       /*
-        * Has to be a linear search because we don't have an auxiliary
-        * search tree yet
-        */
-       k = set1->start;
-       while (1) {
-               struct bkey_packed *n = bkey_next(k);
+               SET_BTREE_NODE_SEQ(n[i]->data, BTREE_NODE_SEQ(b->data) + 1);
+               bch2_bkey_format_init(&format[i]);
+       }
 
-               if (n == vstruct_last(set1))
-                       break;
-               if (k->_data - set1->_data >= (le16_to_cpu(set1->u64s) * 3) / 5)
-                       break;
+       u64s = 0;
+       for_each_btree_node_key(b, k, &iter) {
+               if (bkey_deleted(k))
+                       continue;
 
-               if (bkey_packed(k))
-                       nr_packed++;
-               else
-                       nr_unpacked++;
+               i = u64s >= n1_u64s;
+               u64s += k->u64s;
+               uk = bkey_unpack_key(b, k);
+               if (!i)
+                       n1_pos = uk.p;
+               bch2_bkey_format_add_key(&format[i], &uk);
 
-               prev = k;
-               k = n;
+               nr_keys[i].nr_keys++;
+               nr_keys[i].val_u64s += bkeyp_val_u64s(&b->format, k);
        }
 
-       BUG_ON(!prev);
-       set2_start      = k;
-       set2_end        = vstruct_last(set1);
+       btree_set_min(n[0], b->data->min_key);
+       btree_set_max(n[0], n1_pos);
+       btree_set_min(n[1], bpos_successor(n1_pos));
+       btree_set_max(n[1], b->data->max_key);
 
-       set1->u64s = cpu_to_le16((u64 *) set2_start - set1->_data);
-       set_btree_bset_end(n1, n1->set);
+       for (i = 0; i < 2; i++) {
+               bch2_bkey_format_add_pos(&format[i], n[i]->data->min_key);
+               bch2_bkey_format_add_pos(&format[i], n[i]->data->max_key);
 
-       n1->nr.live_u64s        = le16_to_cpu(set1->u64s);
-       n1->nr.bset_u64s[0]     = le16_to_cpu(set1->u64s);
-       n1->nr.packed_keys      = nr_packed;
-       n1->nr.unpacked_keys    = nr_unpacked;
+               n[i]->data->format = bch2_bkey_format_done(&format[i]);
 
-       n1_pos = bkey_unpack_pos(n1, prev);
-       if (as->c->sb.version < bcachefs_metadata_version_snapshot)
-               n1_pos.snapshot = U32_MAX;
+               unsigned u64s = nr_keys[i].nr_keys * n[i]->data->format.key_u64s +
+                       nr_keys[i].val_u64s;
+               if (__vstruct_bytes(struct btree_node, u64s) > btree_bytes(as->c))
+                       n[i]->data->format = b->format;
 
-       btree_set_max(n1, n1_pos);
-       btree_set_min(n2, bpos_successor(n1->key.k.p));
+               btree_node_set_format(n[i], n[i]->data->format);
+       }
 
-       bch2_bkey_format_init(&s);
-       bch2_bkey_format_add_pos(&s, n2->data->min_key);
-       bch2_bkey_format_add_pos(&s, n2->data->max_key);
+       u64s = 0;
+       for_each_btree_node_key(b, k, &iter) {
+               if (bkey_deleted(k))
+                       continue;
 
-       for (k = set2_start; k != set2_end; k = bkey_next(k)) {
-               struct bkey uk = bkey_unpack_key(n1, k);
-               bch2_bkey_format_add_key(&s, &uk);
-       }
+               i = u64s >= n1_u64s;
+               u64s += k->u64s;
 
-       n2->data->format = bch2_bkey_format_done(&s);
-       btree_node_set_format(n2, n2->data->format);
+               if (bch2_bkey_transform(&n[i]->format, out[i], bkey_packed(k)
+                                       ? &b->format: &bch2_bkey_format_current, k))
+                       out[i]->format = KEY_FORMAT_LOCAL_BTREE;
+               else
+                       bch2_bkey_unpack(b, (void *) out[i], k);
 
-       out = set2->start;
-       memset(&n2->nr, 0, sizeof(n2->nr));
+               out[i]->needs_whiteout = false;
 
-       for (k = set2_start; k != set2_end; k = bkey_next(k)) {
-               BUG_ON(!bch2_bkey_transform(&n2->format, out, bkey_packed(k)
-                                      ? &n1->format : &bch2_bkey_format_current, k));
-               out->format = KEY_FORMAT_LOCAL_BTREE;
-               btree_keys_account_key_add(&n2->nr, 0, out);
-               out = bkey_next(out);
+               btree_keys_account_key_add(&n[i]->nr, 0, out[i]);
+               out[i] = bkey_p_next(out[i]);
        }
 
-       set2->u64s = cpu_to_le16((u64 *) out - set2->_data);
-       set_btree_bset_end(n2, n2->set);
+       for (i = 0; i < 2; i++) {
+               bsets[i]->u64s = cpu_to_le16((u64 *) out[i] - bsets[i]->_data);
 
-       BUG_ON(!set1->u64s);
-       BUG_ON(!set2->u64s);
+               BUG_ON(!bsets[i]->u64s);
 
-       btree_node_reset_sib_u64s(n1);
-       btree_node_reset_sib_u64s(n2);
+               set_btree_bset_end(n[i], n[i]->set);
 
-       bch2_verify_btree_nr_keys(n1);
-       bch2_verify_btree_nr_keys(n2);
+               btree_node_reset_sib_u64s(n[i]);
 
-       if (n1->c.level) {
-               btree_node_interior_verify(as->c, n1);
-               btree_node_interior_verify(as->c, n2);
-       }
+               bch2_verify_btree_nr_keys(n[i]);
 
-       return n2;
+               if (b->c.level)
+                       btree_node_interior_verify(as->c, n[i]);
+       }
 }
 
 /*
@@ -1405,91 +1456,73 @@ static struct btree *__btree_split_node(struct btree_update *as,
  */
 static void btree_split_insert_keys(struct btree_update *as,
                                    struct btree_trans *trans,
-                                   struct btree_path *path,
+                                   btree_path_idx_t path_idx,
                                    struct btree *b,
                                    struct keylist *keys)
 {
-       struct btree_node_iter node_iter;
-       struct bkey_i *k = bch2_keylist_front(keys);
-       struct bkey_packed *src, *dst, *n;
-       struct bset *i;
+       struct btree_path *path = trans->paths + path_idx;
 
-       bch2_btree_node_iter_init(&node_iter, b, &k->k.p);
+       if (!bch2_keylist_empty(keys) &&
+           bpos_le(bch2_keylist_front(keys)->k.p, b->data->max_key)) {
+               struct btree_node_iter node_iter;
 
-       __bch2_btree_insert_keys_interior(as, trans, path, b, node_iter, keys);
-
-       /*
-        * We can't tolerate whiteouts here - with whiteouts there can be
-        * duplicate keys, and it would be rather bad if we picked a duplicate
-        * for the pivot:
-        */
-       i = btree_bset_first(b);
-       src = dst = i->start;
-       while (src != vstruct_last(i)) {
-               n = bkey_next(src);
-               if (!bkey_deleted(src)) {
-                       memmove_u64s_down(dst, src, src->u64s);
-                       dst = bkey_next(dst);
-               }
-               src = n;
-       }
+               bch2_btree_node_iter_init(&node_iter, b, &bch2_keylist_front(keys)->k.p);
 
-       /* Also clear out the unwritten whiteouts area: */
-       b->whiteout_u64s = 0;
+               __bch2_btree_insert_keys_interior(as, trans, path, b, node_iter, keys);
 
-       i->u64s = cpu_to_le16((u64 *) dst - i->_data);
-       set_btree_bset_end(b, b->set);
-
-       BUG_ON(b->nsets != 1 ||
-              b->nr.live_u64s != le16_to_cpu(btree_bset_first(b)->u64s));
-
-       btree_node_interior_verify(as->c, b);
+               btree_node_interior_verify(as->c, b);
+       }
 }
 
-static void btree_split(struct btree_update *as, struct btree_trans *trans,
-                       struct btree_path *path, struct btree *b,
-                       struct keylist *keys, unsigned flags)
+static int btree_split(struct btree_update *as, struct btree_trans *trans,
+                      btree_path_idx_t path, struct btree *b,
+                      struct keylist *keys, unsigned flags)
 {
        struct bch_fs *c = as->c;
-       struct btree *parent = btree_node_parent(path, b);
+       struct btree *parent = btree_node_parent(trans->paths + path, b);
        struct btree *n1, *n2 = NULL, *n3 = NULL;
-       struct btree_path *path1 = NULL, *path2 = NULL;
+       btree_path_idx_t path1 = 0, path2 = 0;
        u64 start_time = local_clock();
+       int ret = 0;
 
        BUG_ON(!parent && (b != btree_node_root(c, b)));
-       BUG_ON(!btree_node_intent_locked(path, btree_node_root(c, b)->c.level));
+       BUG_ON(parent && !btree_node_intent_locked(trans->paths + path, b->c.level + 1));
 
        bch2_btree_interior_update_will_free_node(as, b);
 
-       n1 = bch2_btree_node_alloc_replacement(as, trans, b);
+       if (b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c)) {
+               struct btree *n[2];
 
-       if (keys)
-               btree_split_insert_keys(as, trans, path, n1, keys);
+               trace_and_count(c, btree_node_split, trans, b);
 
-       if (bset_u64s(&n1->set[0]) > BTREE_SPLIT_THRESHOLD(c)) {
-               trace_and_count(c, btree_node_split, c, b);
+               n[0] = n1 = bch2_btree_node_alloc(as, trans, b->c.level);
+               n[1] = n2 = bch2_btree_node_alloc(as, trans, b->c.level);
 
-               n2 = __btree_split_node(as, trans, n1);
+               __btree_split_node(as, trans, b, n);
+
+               if (keys) {
+                       btree_split_insert_keys(as, trans, path, n1, keys);
+                       btree_split_insert_keys(as, trans, path, n2, keys);
+                       BUG_ON(!bch2_keylist_empty(keys));
+               }
 
                bch2_btree_build_aux_trees(n2);
                bch2_btree_build_aux_trees(n1);
+
+               bch2_btree_update_add_new_node(as, n1);
+               bch2_btree_update_add_new_node(as, n2);
                six_unlock_write(&n2->c.lock);
                six_unlock_write(&n1->c.lock);
 
-               path1 = get_unlocked_mut_path(trans, path->btree_id, n1->c.level, n1->key.k.p);
+               path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
                six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
-               mark_btree_node_locked(trans, path1, n1->c.level, SIX_LOCK_intent);
-               bch2_btree_path_level_init(trans, path1, n1);
+               mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
+               bch2_btree_path_level_init(trans, trans->paths + path1, n1);
 
-               path2 = get_unlocked_mut_path(trans, path->btree_id, n2->c.level, n2->key.k.p);
+               path2 = get_unlocked_mut_path(trans, as->btree_id, n2->c.level, n2->key.k.p);
                six_lock_increment(&n2->c.lock, SIX_LOCK_intent);
-               mark_btree_node_locked(trans, path2, n2->c.level, SIX_LOCK_intent);
-               bch2_btree_path_level_init(trans, path2, n2);
-
-               bch2_btree_update_add_new_node(as, n1);
-
-               bch2_btree_node_write(c, n1, SIX_LOCK_intent, 0);
-               bch2_btree_node_write(c, n2, SIX_LOCK_intent, 0);
+               mark_btree_node_locked(trans, trans->paths + path2, n2->c.level, BTREE_NODE_INTENT_LOCKED);
+               bch2_btree_path_level_init(trans, trans->paths + path2, n2);
 
                /*
                 * Note that on recursive parent_keys == keys, so we
@@ -1503,33 +1536,38 @@ static void btree_split(struct btree_update *as, struct btree_trans *trans,
                        /* Depth increases, make a new root */
                        n3 = __btree_root_alloc(as, trans, b->c.level + 1);
 
-                       path2->locks_want++;
-                       BUG_ON(btree_node_locked(path2, n3->c.level));
+                       bch2_btree_update_add_new_node(as, n3);
+                       six_unlock_write(&n3->c.lock);
+
+                       trans->paths[path2].locks_want++;
+                       BUG_ON(btree_node_locked(trans->paths + path2, n3->c.level));
                        six_lock_increment(&n3->c.lock, SIX_LOCK_intent);
-                       mark_btree_node_locked(trans, path2, n3->c.level, SIX_LOCK_intent);
-                       bch2_btree_path_level_init(trans, path2, n3);
+                       mark_btree_node_locked(trans, trans->paths + path2, n3->c.level, BTREE_NODE_INTENT_LOCKED);
+                       bch2_btree_path_level_init(trans, trans->paths + path2, n3);
 
                        n3->sib_u64s[0] = U16_MAX;
                        n3->sib_u64s[1] = U16_MAX;
 
                        btree_split_insert_keys(as, trans, path, n3, &as->parent_keys);
-
-                       bch2_btree_node_write(c, n3, SIX_LOCK_intent, 0);
                }
        } else {
-               trace_and_count(c, btree_node_compact, c, b);
+               trace_and_count(c, btree_node_compact, trans, b);
 
-               bch2_btree_build_aux_trees(n1);
-               six_unlock_write(&n1->c.lock);
+               n1 = bch2_btree_node_alloc_replacement(as, trans, b);
 
-               path1 = get_unlocked_mut_path(trans, path->btree_id, n1->c.level, n1->key.k.p);
-               six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
-               mark_btree_node_locked(trans, path1, n1->c.level, SIX_LOCK_intent);
-               bch2_btree_path_level_init(trans, path1, n1);
+               if (keys) {
+                       btree_split_insert_keys(as, trans, path, n1, keys);
+                       BUG_ON(!bch2_keylist_empty(keys));
+               }
 
+               bch2_btree_build_aux_trees(n1);
                bch2_btree_update_add_new_node(as, n1);
+               six_unlock_write(&n1->c.lock);
 
-               bch2_btree_node_write(c, n1, SIX_LOCK_intent, 0);
+               path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
+               six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
+               mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
+               bch2_btree_path_level_init(trans, trans->paths + path1, n1);
 
                if (parent)
                        bch2_keylist_add(&as->parent_keys, &n1->key);
@@ -1539,19 +1577,26 @@ static void btree_split(struct btree_update *as, struct btree_trans *trans,
 
        if (parent) {
                /* Split a non root node */
-               bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys, flags);
+               ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys, flags);
+               if (ret)
+                       goto err;
        } else if (n3) {
-               bch2_btree_set_root(as, trans, path, n3);
+               bch2_btree_set_root(as, trans, trans->paths + path, n3);
        } else {
                /* Root filled up but didn't need to be split */
-               bch2_btree_set_root(as, trans, path, n1);
+               bch2_btree_set_root(as, trans, trans->paths + path, n1);
        }
 
-       bch2_btree_update_get_open_buckets(as, n1);
-       if (n2)
-               bch2_btree_update_get_open_buckets(as, n2);
-       if (n3)
+       if (n3) {
                bch2_btree_update_get_open_buckets(as, n3);
+               bch2_btree_node_write(c, n3, SIX_LOCK_intent, 0);
+       }
+       if (n2) {
+               bch2_btree_update_get_open_buckets(as, n2);
+               bch2_btree_node_write(c, n2, SIX_LOCK_intent, 0);
+       }
+       bch2_btree_update_get_open_buckets(as, n1);
+       bch2_btree_node_write(c, n1, SIX_LOCK_intent, 0);
 
        /*
         * The old node must be freed (in memory) _before_ unlocking the new
@@ -1559,26 +1604,26 @@ static void btree_split(struct btree_update *as, struct btree_trans *trans,
         * node after another thread has locked and updated the new node, thus
         * seeing stale data:
         */
-       bch2_btree_node_free_inmem(trans, path, b);
+       bch2_btree_node_free_inmem(trans, trans->paths + path, b);
 
        if (n3)
-               bch2_trans_node_add(trans, n3);
+               bch2_trans_node_add(trans, trans->paths + path, n3);
        if (n2)
-               bch2_trans_node_add(trans, n2);
-       bch2_trans_node_add(trans, n1);
+               bch2_trans_node_add(trans, trans->paths + path2, n2);
+       bch2_trans_node_add(trans, trans->paths + path1, n1);
 
        if (n3)
                six_unlock_intent(&n3->c.lock);
        if (n2)
                six_unlock_intent(&n2->c.lock);
        six_unlock_intent(&n1->c.lock);
-
+out:
        if (path2) {
-               __bch2_btree_path_unlock(trans, path2);
+               __bch2_btree_path_unlock(trans, trans->paths + path2);
                bch2_path_put(trans, path2, true);
        }
        if (path1) {
-               __bch2_btree_path_unlock(trans, path1);
+               __bch2_btree_path_unlock(trans, trans->paths + path1);
                bch2_path_put(trans, path1, true);
        }
 
@@ -1588,6 +1633,14 @@ static void btree_split(struct btree_update *as, struct btree_trans *trans,
                               ? BCH_TIME_btree_node_split
                               : BCH_TIME_btree_node_compact],
                               start_time);
+       return ret;
+err:
+       if (n3)
+               bch2_btree_node_free_never_used(as, trans, n3);
+       if (n2)
+               bch2_btree_node_free_never_used(as, trans, n2);
+       bch2_btree_node_free_never_used(as, trans, n1);
+       goto out;
 }
 
 static void
@@ -1598,46 +1651,57 @@ bch2_btree_insert_keys_interior(struct btree_update *as,
                                struct keylist *keys)
 {
        struct btree_path *linked;
+       unsigned i;
 
        __bch2_btree_insert_keys_interior(as, trans, path, b,
                                          path->l[b->c.level].iter, keys);
 
        btree_update_updated_node(as, b);
 
-       trans_for_each_path_with_node(trans, b, linked)
+       trans_for_each_path_with_node(trans, b, linked, i)
                bch2_btree_node_iter_peek(&linked->l[b->c.level].iter, b);
 
        bch2_trans_verify_paths(trans);
 }
 
 /**
- * bch_btree_insert_node - insert bkeys into a given btree node
+ * bch2_btree_insert_node - insert bkeys into a given btree node
  *
- * @iter:              btree iterator
+ * @as:                        btree_update object
+ * @trans:             btree_trans object
+ * @path_idx:          path that points to current node
+ * @b:                 node to insert keys into
  * @keys:              list of keys to insert
- * @hook:              insert callback
- * @persistent:                if not null, @persistent will wait on journal write
+ * @flags:             transaction commit flags
+ *
+ * Returns: 0 on success, typically transaction restart error on failure
  *
  * Inserts as many keys as it can into a given btree node, splitting it if full.
  * If a split occurred, this function will return early. This can only happen
  * for leaf nodes -- inserts into interior nodes have to be atomic.
  */
-static void bch2_btree_insert_node(struct btree_update *as, struct btree_trans *trans,
-                                  struct btree_path *path, struct btree *b,
-                                  struct keylist *keys, unsigned flags)
+static int bch2_btree_insert_node(struct btree_update *as, struct btree_trans *trans,
+                                 btree_path_idx_t path_idx, struct btree *b,
+                                 struct keylist *keys, unsigned flags)
 {
        struct bch_fs *c = as->c;
+       struct btree_path *path = trans->paths + path_idx;
        int old_u64s = le16_to_cpu(btree_bset_last(b)->u64s);
        int old_live_u64s = b->nr.live_u64s;
        int live_u64s_added, u64s_added;
+       int ret;
 
        lockdep_assert_held(&c->gc_lock);
-       BUG_ON(!btree_node_intent_locked(path, btree_node_root(c, b)->c.level));
+       BUG_ON(!btree_node_intent_locked(path, b->c.level));
        BUG_ON(!b->c.level);
        BUG_ON(!as || as->b);
        bch2_verify_keylist_sorted(keys);
 
-       bch2_btree_node_lock_for_insert(trans, path, b);
+       ret = bch2_btree_node_lock_write(trans, path, &b->c);
+       if (ret)
+               return ret;
+
+       bch2_btree_node_prep_for_write(trans, path, b);
 
        if (!bch2_btree_node_insert_fits(c, b, bch2_keylist_u64s(keys))) {
                bch2_btree_node_unlock_write(trans, path, b);
@@ -1663,42 +1727,60 @@ static void bch2_btree_insert_node(struct btree_update *as, struct btree_trans *
        bch2_btree_node_unlock_write(trans, path, b);
 
        btree_node_interior_verify(c, b);
-       return;
+       return 0;
 split:
-       btree_split(as, trans, path, b, keys, flags);
+       /*
+        * We could attempt to avoid the transaction restart, by calling
+        * bch2_btree_path_upgrade() and allocating more nodes:
+        */
+       if (b->c.level >= as->update_level) {
+               trace_and_count(c, trans_restart_split_race, trans, _THIS_IP_, b);
+               return btree_trans_restart(trans, BCH_ERR_transaction_restart_split_race);
+       }
+
+       return btree_split(as, trans, path_idx, b, keys, flags);
 }
 
 int bch2_btree_split_leaf(struct btree_trans *trans,
-                         struct btree_path *path,
+                         btree_path_idx_t path,
                          unsigned flags)
 {
-       struct btree *b = path_l(path)->b;
+       /* btree_split & merge may both cause paths array to be reallocated */
+
+       struct btree *b = path_l(trans->paths + path)->b;
        struct btree_update *as;
        unsigned l;
        int ret = 0;
 
-       as = bch2_btree_update_start(trans, path, path->level,
+       as = bch2_btree_update_start(trans, trans->paths + path,
+                                    trans->paths[path].level,
                                     true, flags);
        if (IS_ERR(as))
                return PTR_ERR(as);
 
-       btree_split(as, trans, path, b, NULL, flags);
+       ret = btree_split(as, trans, path, b, NULL, flags);
+       if (ret) {
+               bch2_btree_update_free(as, trans);
+               return ret;
+       }
+
        bch2_btree_update_done(as, trans);
 
-       for (l = path->level + 1; btree_path_node(path, l) && !ret; l++)
+       for (l = trans->paths[path].level + 1;
+            btree_node_intent_locked(&trans->paths[path], l) && !ret;
+            l++)
                ret = bch2_foreground_maybe_merge(trans, path, l, flags);
 
        return ret;
 }
 
 int __bch2_foreground_maybe_merge(struct btree_trans *trans,
-                                 struct btree_path *path,
+                                 btree_path_idx_t path,
                                  unsigned level,
                                  unsigned flags,
                                  enum btree_node_sibling sib)
 {
        struct bch_fs *c = trans->c;
-       struct btree_path *sib_path = NULL, *new_path = NULL;
        struct btree_update *as;
        struct bkey_format_state new_s;
        struct bkey_format new_f;
@@ -1706,16 +1788,18 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        struct btree *b, *m, *n, *prev, *next, *parent;
        struct bpos sib_pos;
        size_t sib_u64s;
+       enum btree_id btree = trans->paths[path].btree_id;
+       btree_path_idx_t sib_path = 0, new_path = 0;
        u64 start_time = local_clock();
        int ret = 0;
 
-       BUG_ON(!path->should_be_locked);
-       BUG_ON(!btree_node_locked(path, level));
+       BUG_ON(!trans->paths[path].should_be_locked);
+       BUG_ON(!btree_node_locked(&trans->paths[path], level));
 
-       b = path->l[level].b;
+       b = trans->paths[path].l[level].b;
 
-       if ((sib == btree_prev_sib && !bpos_cmp(b->data->min_key, POS_MIN)) ||
-           (sib == btree_next_sib && !bpos_cmp(b->data->max_key, SPOS_MAX))) {
+       if ((sib == btree_prev_sib && bpos_eq(b->data->min_key, POS_MIN)) ||
+           (sib == btree_next_sib && bpos_eq(b->data->max_key, SPOS_MAX))) {
                b->sib_u64s[sib] = U16_MAX;
                return 0;
        }
@@ -1724,18 +1808,18 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
                ? bpos_predecessor(b->data->min_key)
                : bpos_successor(b->data->max_key);
 
-       sib_path = bch2_path_get(trans, path->btree_id, sib_pos,
+       sib_path = bch2_path_get(trans, btree, sib_pos,
                                 U8_MAX, level, BTREE_ITER_INTENT, _THIS_IP_);
        ret = bch2_btree_path_traverse(trans, sib_path, false);
        if (ret)
                goto err;
 
-       btree_path_set_should_be_locked(sib_path);
+       btree_path_set_should_be_locked(trans->paths + sib_path);
 
-       m = sib_path->l[level].b;
+       m = trans->paths[sib_path].l[level].b;
 
-       if (btree_node_parent(path, b) !=
-           btree_node_parent(sib_path, m)) {
+       if (btree_node_parent(trans->paths + path, b) !=
+           btree_node_parent(trans->paths + sib_path, m)) {
                b->sib_u64s[sib] = U16_MAX;
                goto out;
        }
@@ -1748,16 +1832,16 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
                next = m;
        }
 
-       if (bkey_cmp(bpos_successor(prev->data->max_key), next->data->min_key)) {
+       if (!bpos_eq(bpos_successor(prev->data->max_key), next->data->min_key)) {
                struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 
                bch2_bpos_to_text(&buf1, prev->data->max_key);
                bch2_bpos_to_text(&buf2, next->data->min_key);
                bch_err(c,
-                       "btree topology error in btree merge:\n"
+                       "%s(): btree topology error:\n"
                        "  prev ends at   %s\n"
                        "  next starts at %s",
-                       buf1.buf, buf2.buf);
+                       __func__, buf1.buf, buf2.buf);
                printbuf_exit(&buf1);
                printbuf_exit(&buf2);
                bch2_topology_error(c);
@@ -1772,8 +1856,8 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        bch2_bkey_format_add_pos(&new_s, next->data->max_key);
        new_f = bch2_bkey_format_done(&new_s);
 
-       sib_u64s = btree_node_u64s_with_format(b, &new_f) +
-               btree_node_u64s_with_format(m, &new_f);
+       sib_u64s = btree_node_u64s_with_format(b->nr, &b->format, &new_f) +
+               btree_node_u64s_with_format(m->nr, &m->format, &new_f);
 
        if (sib_u64s > BTREE_FOREGROUND_MERGE_HYSTERESIS(c)) {
                sib_u64s -= BTREE_FOREGROUND_MERGE_HYSTERESIS(c);
@@ -1788,16 +1872,14 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        if (b->sib_u64s[sib] > c->btree_foreground_merge_threshold)
                goto out;
 
-       parent = btree_node_parent(path, b);
-       as = bch2_btree_update_start(trans, path, level, false,
-                        BTREE_INSERT_NOFAIL|
-                        BTREE_INSERT_USE_RESERVE|
-                        flags);
+       parent = btree_node_parent(trans->paths + path, b);
+       as = bch2_btree_update_start(trans, trans->paths + path, level, false,
+                                    BCH_TRANS_COMMIT_no_enospc|flags);
        ret = PTR_ERR_OR_ZERO(as);
        if (ret)
                goto err;
 
-       trace_and_count(c, btree_node_merge, c, b);
+       trace_and_count(c, btree_node_merge, trans, b);
 
        bch2_btree_interior_update_will_free_node(as, b);
        bch2_btree_interior_update_will_free_node(as, m);
@@ -1811,8 +1893,6 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        btree_set_min(n, prev->data->min_key);
        btree_set_max(n, next->data->max_key);
 
-       bch2_btree_update_add_new_node(as, n);
-
        n->data->format  = new_f;
        btree_node_set_format(n, new_f);
 
@@ -1820,14 +1900,13 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
        bch2_btree_sort_into(c, n, next);
 
        bch2_btree_build_aux_trees(n);
+       bch2_btree_update_add_new_node(as, n);
        six_unlock_write(&n->c.lock);
 
-       new_path = get_unlocked_mut_path(trans, path->btree_id, n->c.level, n->key.k.p);
+       new_path = get_unlocked_mut_path(trans, btree, n->c.level, n->key.k.p);
        six_lock_increment(&n->c.lock, SIX_LOCK_intent);
-       mark_btree_node_locked(trans, new_path, n->c.level, SIX_LOCK_intent);
-       bch2_btree_path_level_init(trans, new_path, n);
-
-       bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
+       mark_btree_node_locked(trans, trans->paths + new_path, n->c.level, BTREE_NODE_INTENT_LOCKED);
+       bch2_btree_path_level_init(trans, trans->paths + new_path, n);
 
        bkey_init(&delete.k);
        delete.k.p = prev->key.k.p;
@@ -1836,16 +1915,19 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
 
        bch2_trans_verify_paths(trans);
 
-       bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys, flags);
+       ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys, flags);
+       if (ret)
+               goto err_free_update;
 
        bch2_trans_verify_paths(trans);
 
        bch2_btree_update_get_open_buckets(as, n);
+       bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
 
-       bch2_btree_node_free_inmem(trans, path, b);
-       bch2_btree_node_free_inmem(trans, sib_path, m);
+       bch2_btree_node_free_inmem(trans, trans->paths + path, b);
+       bch2_btree_node_free_inmem(trans, trans->paths + sib_path, m);
 
-       bch2_trans_node_add(trans, n);
+       bch2_trans_node_add(trans, trans->paths + path, n);
 
        bch2_trans_verify_paths(trans);
 
@@ -1861,27 +1943,28 @@ err:
        bch2_path_put(trans, sib_path, true);
        bch2_trans_verify_locks(trans);
        return ret;
+err_free_update:
+       bch2_btree_node_free_never_used(as, trans, n);
+       bch2_btree_update_free(as, trans);
+       goto out;
 }
 
-/**
- * bch_btree_node_rewrite - Rewrite/move a btree node
- */
 int bch2_btree_node_rewrite(struct btree_trans *trans,
                            struct btree_iter *iter,
                            struct btree *b,
                            unsigned flags)
 {
        struct bch_fs *c = trans->c;
-       struct btree_path *new_path = NULL;
        struct btree *n, *parent;
        struct btree_update *as;
+       btree_path_idx_t new_path = 0;
        int ret;
 
-       flags |= BTREE_INSERT_NOFAIL;
+       flags |= BCH_TRANS_COMMIT_no_enospc;
 
-       parent = btree_node_parent(iter->path, b);
-       as = bch2_btree_update_start(trans, iter->path, b->c.level,
-                                    false, flags);
+       struct btree_path *path = btree_iter_path(trans, iter);
+       parent = btree_node_parent(path, b);
+       as = bch2_btree_update_start(trans, path, b->c.level, false, flags);
        ret = PTR_ERR_OR_ZERO(as);
        if (ret)
                goto out;
@@ -1889,45 +1972,52 @@ int bch2_btree_node_rewrite(struct btree_trans *trans,
        bch2_btree_interior_update_will_free_node(as, b);
 
        n = bch2_btree_node_alloc_replacement(as, trans, b);
-       bch2_btree_update_add_new_node(as, n);
 
        bch2_btree_build_aux_trees(n);
+       bch2_btree_update_add_new_node(as, n);
        six_unlock_write(&n->c.lock);
 
        new_path = get_unlocked_mut_path(trans, iter->btree_id, n->c.level, n->key.k.p);
        six_lock_increment(&n->c.lock, SIX_LOCK_intent);
-       mark_btree_node_locked(trans, new_path, n->c.level, SIX_LOCK_intent);
-       bch2_btree_path_level_init(trans, new_path, n);
+       mark_btree_node_locked(trans, trans->paths + new_path, n->c.level, BTREE_NODE_INTENT_LOCKED);
+       bch2_btree_path_level_init(trans, trans->paths + new_path, n);
 
-       trace_and_count(c, btree_node_rewrite, c, b);
-
-       bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
+       trace_and_count(c, btree_node_rewrite, trans, b);
 
        if (parent) {
                bch2_keylist_add(&as->parent_keys, &n->key);
-               bch2_btree_insert_node(as, trans, iter->path, parent,
-                                      &as->parent_keys, flags);
+               ret = bch2_btree_insert_node(as, trans, iter->path,
+                                            parent, &as->parent_keys, flags);
+               if (ret)
+                       goto err;
        } else {
-               bch2_btree_set_root(as, trans, iter->path, n);
+               bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n);
        }
 
        bch2_btree_update_get_open_buckets(as, n);
+       bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
 
-       bch2_btree_node_free_inmem(trans, iter->path, b);
+       bch2_btree_node_free_inmem(trans, btree_iter_path(trans, iter), b);
 
-       bch2_trans_node_add(trans, n);
+       bch2_trans_node_add(trans, trans->paths + iter->path, n);
        six_unlock_intent(&n->c.lock);
 
        bch2_btree_update_done(as, trans);
-       bch2_path_put(trans, new_path, true);
 out:
-       bch2_btree_path_downgrade(trans, iter->path);
+       if (new_path)
+               bch2_path_put(trans, new_path, true);
+       bch2_trans_downgrade(trans);
        return ret;
+err:
+       bch2_btree_node_free_never_used(as, trans, n);
+       bch2_btree_update_free(as, trans);
+       goto out;
 }
 
 struct async_btree_rewrite {
        struct bch_fs           *c;
        struct work_struct      work;
+       struct list_head        list;
        enum btree_id           btree_id;
        unsigned                level;
        struct bpos             pos;
@@ -1937,6 +2027,7 @@ struct async_btree_rewrite {
 static int async_btree_node_rewrite_trans(struct btree_trans *trans,
                                          struct async_btree_rewrite *a)
 {
+       struct bch_fs *c = trans->c;
        struct btree_iter iter;
        struct btree *b;
        int ret;
@@ -1948,38 +2039,48 @@ static int async_btree_node_rewrite_trans(struct btree_trans *trans,
        if (ret)
                goto out;
 
-       if (!b || b->data->keys.seq != a->seq)
+       if (!b || b->data->keys.seq != a->seq) {
+               struct printbuf buf = PRINTBUF;
+
+               if (b)
+                       bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
+               else
+                       prt_str(&buf, "(null");
+               bch_info(c, "%s: node to rewrite not found:, searching for seq %llu, got\n%s",
+                        __func__, a->seq, buf.buf);
+               printbuf_exit(&buf);
                goto out;
+       }
 
        ret = bch2_btree_node_rewrite(trans, &iter, b, 0);
-out :
+out:
        bch2_trans_iter_exit(trans, &iter);
 
        return ret;
 }
 
-void async_btree_node_rewrite_work(struct work_struct *work)
+static void async_btree_node_rewrite_work(struct work_struct *work)
 {
        struct async_btree_rewrite *a =
                container_of(work, struct async_btree_rewrite, work);
        struct bch_fs *c = a->c;
+       int ret;
 
-       bch2_trans_do(c, NULL, NULL, 0,
-                     async_btree_node_rewrite_trans(&trans, a));
-       percpu_ref_put(&c->writes);
+       ret = bch2_trans_do(c, NULL, NULL, 0,
+                     async_btree_node_rewrite_trans(trans, a));
+       bch_err_fn(c, ret);
+       bch2_write_ref_put(c, BCH_WRITE_REF_node_rewrite);
        kfree(a);
 }
 
 void bch2_btree_node_rewrite_async(struct bch_fs *c, struct btree *b)
 {
        struct async_btree_rewrite *a;
-
-       if (!percpu_ref_tryget_live(&c->writes))
-               return;
+       int ret;
 
        a = kmalloc(sizeof(*a), GFP_NOFS);
        if (!a) {
-               percpu_ref_put(&c->writes);
+               bch_err(c, "%s: error allocating memory", __func__);
                return;
        }
 
@@ -1988,15 +2089,67 @@ void bch2_btree_node_rewrite_async(struct bch_fs *c, struct btree *b)
        a->level        = b->c.level;
        a->pos          = b->key.k.p;
        a->seq          = b->data->keys.seq;
-
        INIT_WORK(&a->work, async_btree_node_rewrite_work);
+
+       if (unlikely(!test_bit(BCH_FS_may_go_rw, &c->flags))) {
+               mutex_lock(&c->pending_node_rewrites_lock);
+               list_add(&a->list, &c->pending_node_rewrites);
+               mutex_unlock(&c->pending_node_rewrites_lock);
+               return;
+       }
+
+       if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_node_rewrite)) {
+               if (test_bit(BCH_FS_started, &c->flags)) {
+                       bch_err(c, "%s: error getting c->writes ref", __func__);
+                       kfree(a);
+                       return;
+               }
+
+               ret = bch2_fs_read_write_early(c);
+               bch_err_msg(c, ret, "going read-write");
+               if (ret) {
+                       kfree(a);
+                       return;
+               }
+
+               bch2_write_ref_get(c, BCH_WRITE_REF_node_rewrite);
+       }
+
        queue_work(c->btree_interior_update_worker, &a->work);
 }
 
+void bch2_do_pending_node_rewrites(struct bch_fs *c)
+{
+       struct async_btree_rewrite *a, *n;
+
+       mutex_lock(&c->pending_node_rewrites_lock);
+       list_for_each_entry_safe(a, n, &c->pending_node_rewrites, list) {
+               list_del(&a->list);
+
+               bch2_write_ref_get(c, BCH_WRITE_REF_node_rewrite);
+               queue_work(c->btree_interior_update_worker, &a->work);
+       }
+       mutex_unlock(&c->pending_node_rewrites_lock);
+}
+
+void bch2_free_pending_node_rewrites(struct bch_fs *c)
+{
+       struct async_btree_rewrite *a, *n;
+
+       mutex_lock(&c->pending_node_rewrites_lock);
+       list_for_each_entry_safe(a, n, &c->pending_node_rewrites, list) {
+               list_del(&a->list);
+
+               kfree(a);
+       }
+       mutex_unlock(&c->pending_node_rewrites_lock);
+}
+
 static int __bch2_btree_node_update_key(struct btree_trans *trans,
                                        struct btree_iter *iter,
                                        struct btree *b, struct btree *new_hash,
                                        struct bkey_i *new_key,
+                                       unsigned commit_flags,
                                        bool skip_triggers)
 {
        struct bch_fs *c = trans->c;
@@ -2023,7 +2176,7 @@ static int __bch2_btree_node_update_key(struct btree_trans *trans,
                BUG_ON(ret);
        }
 
-       parent = btree_node_parent(iter->path, b);
+       parent = btree_node_parent(btree_iter_path(trans, iter), b);
        if (parent) {
                bch2_trans_copy_iter(&iter2, iter);
 
@@ -2031,12 +2184,13 @@ static int __bch2_btree_node_update_key(struct btree_trans *trans,
                                iter2.flags & BTREE_ITER_INTENT,
                                _THIS_IP_);
 
-               BUG_ON(iter2.path->level != b->c.level);
-               BUG_ON(bpos_cmp(iter2.path->pos, new_key->k.p));
+               struct btree_path *path2 = btree_iter_path(trans, &iter2);
+               BUG_ON(path2->level != b->c.level);
+               BUG_ON(!bpos_eq(path2->pos, new_key->k.p));
 
-               btree_path_set_level_up(trans, iter2.path);
+               btree_path_set_level_up(trans, path2);
 
-               bch2_btree_path_check_sort(trans, iter2.path, 0);
+               trans->paths_sorted = false;
 
                ret   = bch2_btree_iter_traverse(&iter2) ?:
                        bch2_trans_update(trans, &iter2, new_key, BTREE_TRIGGER_NORUN);
@@ -2045,28 +2199,23 @@ static int __bch2_btree_node_update_key(struct btree_trans *trans,
        } else {
                BUG_ON(btree_node_root(c, b) != b);
 
-               ret = darray_make_room(&trans->extra_journal_entries,
+               struct jset_entry *e = bch2_trans_jset_entry_alloc(trans,
                                       jset_u64s(new_key->k.u64s));
+               ret = PTR_ERR_OR_ZERO(e);
                if (ret)
                        return ret;
 
-               journal_entry_set((void *) &darray_top(trans->extra_journal_entries),
+               journal_entry_set(e,
                                  BCH_JSET_ENTRY_btree_root,
                                  b->c.btree_id, b->c.level,
                                  new_key, new_key->k.u64s);
-               trans->extra_journal_entries.nr += jset_u64s(new_key->k.u64s);
        }
 
-       ret = bch2_trans_commit(trans, NULL, NULL,
-                               BTREE_INSERT_NOFAIL|
-                               BTREE_INSERT_NOCHECK_RW|
-                               BTREE_INSERT_USE_RESERVE|
-                               BTREE_INSERT_JOURNAL_RECLAIM|
-                               JOURNAL_WATERMARK_reserved);
+       ret = bch2_trans_commit(trans, NULL, NULL, commit_flags);
        if (ret)
                goto err;
 
-       bch2_btree_node_lock_write_nofail(trans, iter->path, &b->c);
+       bch2_btree_node_lock_write_nofail(trans, btree_iter_path(trans, iter), &b->c);
 
        if (new_hash) {
                mutex_lock(&c->btree_cache.lock);
@@ -2081,7 +2230,7 @@ static int __bch2_btree_node_update_key(struct btree_trans *trans,
                bkey_copy(&b->key, new_key);
        }
 
-       bch2_btree_node_unlock_write(trans, iter->path, b);
+       bch2_btree_node_unlock_write(trans, btree_iter_path(trans, iter), b);
 out:
        bch2_trans_iter_exit(trans, &iter2);
        return ret;
@@ -2096,11 +2245,11 @@ err:
 
 int bch2_btree_node_update_key(struct btree_trans *trans, struct btree_iter *iter,
                               struct btree *b, struct bkey_i *new_key,
-                              bool skip_triggers)
+                              unsigned commit_flags, bool skip_triggers)
 {
        struct bch_fs *c = trans->c;
        struct btree *new_hash = NULL;
-       struct btree_path *path = iter->path;
+       struct btree_path *path = btree_iter_path(trans, iter);
        struct closure cl;
        int ret = 0;
 
@@ -2115,21 +2264,19 @@ int bch2_btree_node_update_key(struct btree_trans *trans, struct btree_iter *ite
         * btree_iter_traverse():
         */
        if (btree_ptr_hash_val(new_key) != b->hash_val) {
-               ret = bch2_btree_cache_cannibalize_lock(c, &cl);
+               ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
                if (ret) {
-                       bch2_trans_unlock(trans);
-                       closure_sync(&cl);
-                       ret = bch2_trans_relock(trans);
+                       ret = drop_locks_do(trans, (closure_sync(&cl), 0));
                        if (ret)
                                return ret;
                }
 
-               new_hash = bch2_btree_node_mem_alloc(c, false);
+               new_hash = bch2_btree_node_mem_alloc(trans, false);
        }
 
        path->intent_ref++;
-       ret = __bch2_btree_node_update_key(trans, iter, b, new_hash,
-                                          new_key, skip_triggers);
+       ret = __bch2_btree_node_update_key(trans, iter, b, new_hash, new_key,
+                                          commit_flags, skip_triggers);
        --path->intent_ref;
 
        if (new_hash) {
@@ -2141,13 +2288,13 @@ int bch2_btree_node_update_key(struct btree_trans *trans, struct btree_iter *ite
                six_unlock_intent(&new_hash->c.lock);
        }
        closure_sync(&cl);
-       bch2_btree_cache_cannibalize_unlock(c);
+       bch2_btree_cache_cannibalize_unlock(trans);
        return ret;
 }
 
 int bch2_btree_node_update_key_get_iter(struct btree_trans *trans,
                                        struct btree *b, struct bkey_i *new_key,
-                                       bool skip_triggers)
+                                       unsigned commit_flags, bool skip_triggers)
 {
        struct btree_iter iter;
        int ret;
@@ -2160,7 +2307,7 @@ int bch2_btree_node_update_key_get_iter(struct btree_trans *trans,
                goto out;
 
        /* has node been freed? */
-       if (iter.path->l[b->c.level].b != b) {
+       if (btree_iter_path(trans, &iter)->l[b->c.level].b != b) {
                /* node has been freed: */
                BUG_ON(!btree_node_dying(b));
                goto out;
@@ -2168,7 +2315,12 @@ int bch2_btree_node_update_key_get_iter(struct btree_trans *trans,
 
        BUG_ON(!btree_node_hashed(b));
 
-       ret = bch2_btree_node_update_key(trans, &iter, b, new_key, skip_triggers);
+       struct bch_extent_ptr *ptr;
+       bch2_bkey_drop_ptrs(bkey_i_to_s(new_key), ptr,
+                           !bch2_bkey_has_device(bkey_i_to_s(&b->key), ptr->dev));
+
+       ret = bch2_btree_node_update_key(trans, &iter, b, new_key,
+                                        commit_flags, skip_triggers);
 out:
        bch2_trans_iter_exit(trans, &iter);
        return ret;
@@ -2187,8 +2339,9 @@ void bch2_btree_set_root_for_read(struct bch_fs *c, struct btree *b)
        bch2_btree_set_root_inmem(c, b);
 }
 
-void bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id)
+static int __bch2_btree_root_alloc(struct btree_trans *trans, enum btree_id id)
 {
+       struct bch_fs *c = trans->c;
        struct closure cl;
        struct btree *b;
        int ret;
@@ -2196,12 +2349,12 @@ void bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id)
        closure_init_stack(&cl);
 
        do {
-               ret = bch2_btree_cache_cannibalize_lock(c, &cl);
+               ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
                closure_sync(&cl);
        } while (ret);
 
-       b = bch2_btree_node_mem_alloc(c, false);
-       bch2_btree_cache_cannibalize_unlock(c);
+       b = bch2_btree_node_mem_alloc(trans, false);
+       bch2_btree_cache_cannibalize_unlock(trans);
 
        set_btree_node_fake(b);
        set_btree_node_need_rewrite(b);
@@ -2229,6 +2382,12 @@ void bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id)
 
        six_unlock_write(&b->c.lock);
        six_unlock_intent(&b->c.lock);
+       return 0;
+}
+
+void bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id)
+{
+       bch2_trans_run(c, __bch2_btree_root_alloc(trans, id));
 }
 
 void bch2_btree_updates_to_text(struct printbuf *out, struct bch_fs *c)
@@ -2241,7 +2400,7 @@ void bch2_btree_updates_to_text(struct printbuf *out, struct bch_fs *c)
                       as,
                       as->mode,
                       as->nodes_written,
-                      atomic_read(&as->cl.remaining) & CLOSURE_REMAINING_MASK,
+                      closure_nr_remaining(&as->cl),
                       as->journal.seq);
        mutex_unlock(&c->btree_interior_update_lock);
 }
@@ -2267,48 +2426,37 @@ bool bch2_btree_interior_updates_flush(struct bch_fs *c)
        return ret;
 }
 
-void bch2_journal_entries_to_btree_roots(struct bch_fs *c, struct jset *jset)
+void bch2_journal_entry_to_btree_root(struct bch_fs *c, struct jset_entry *entry)
 {
-       struct btree_root *r;
-       struct jset_entry *entry;
+       struct btree_root *r = bch2_btree_id_root(c, entry->btree_id);
 
        mutex_lock(&c->btree_root_lock);
 
-       vstruct_for_each(jset, entry)
-               if (entry->type == BCH_JSET_ENTRY_btree_root) {
-                       r = &c->btree_roots[entry->btree_id];
-                       r->level = entry->level;
-                       r->alive = true;
-                       bkey_copy(&r->key, &entry->start[0]);
-               }
+       r->level = entry->level;
+       r->alive = true;
+       bkey_copy(&r->key, (struct bkey_i *) entry->start);
 
        mutex_unlock(&c->btree_root_lock);
 }
 
 struct jset_entry *
 bch2_btree_roots_to_journal_entries(struct bch_fs *c,
-                                   struct jset_entry *start,
-                                   struct jset_entry *end)
+                                   struct jset_entry *end,
+                                   unsigned long skip)
 {
-       struct jset_entry *entry;
-       unsigned long have = 0;
        unsigned i;
 
-       for (entry = start; entry < end; entry = vstruct_next(entry))
-               if (entry->type == BCH_JSET_ENTRY_btree_root)
-                       __set_bit(entry->btree_id, &have);
-
        mutex_lock(&c->btree_root_lock);
 
-       for (i = 0; i < BTREE_ID_NR; i++)
-               if (c->btree_roots[i].alive && !test_bit(i, &have)) {
-                       journal_entry_set(end,
-                                         BCH_JSET_ENTRY_btree_root,
-                                         i, c->btree_roots[i].level,
-                                         &c->btree_roots[i].key,
-                                         c->btree_roots[i].key.u64s);
+       for (i = 0; i < btree_id_nr_alive(c); i++) {
+               struct btree_root *r = bch2_btree_id_root(c, i);
+
+               if (r->alive && !test_bit(i, &skip)) {
+                       journal_entry_set(end, BCH_JSET_ENTRY_btree_root,
+                                         i, r->level, &r->key, r->key.k.u64s);
                        end = vstruct_next(end);
                }
+       }
 
        mutex_unlock(&c->btree_root_lock);
 
@@ -2322,7 +2470,7 @@ void bch2_fs_btree_interior_update_exit(struct bch_fs *c)
        mempool_exit(&c->btree_interior_update_pool);
 }
 
-int bch2_fs_btree_interior_update_init(struct bch_fs *c)
+void bch2_fs_btree_interior_update_init_early(struct bch_fs *c)
 {
        mutex_init(&c->btree_reserve_cache_lock);
        INIT_LIST_HEAD(&c->btree_interior_update_list);
@@ -2330,11 +2478,20 @@ int bch2_fs_btree_interior_update_init(struct bch_fs *c)
        mutex_init(&c->btree_interior_update_lock);
        INIT_WORK(&c->btree_interior_update_work, btree_interior_update_work);
 
+       INIT_LIST_HEAD(&c->pending_node_rewrites);
+       mutex_init(&c->pending_node_rewrites_lock);
+}
+
+int bch2_fs_btree_interior_update_init(struct bch_fs *c)
+{
        c->btree_interior_update_worker =
                alloc_workqueue("btree_update", WQ_UNBOUND|WQ_MEM_RECLAIM, 1);
        if (!c->btree_interior_update_worker)
-               return -ENOMEM;
+               return -BCH_ERR_ENOMEM_btree_interior_update_worker_init;
 
-       return mempool_init_kmalloc_pool(&c->btree_interior_update_pool, 1,
-                                        sizeof(struct btree_update));
+       if (mempool_init_kmalloc_pool(&c->btree_interior_update_pool, 1,
+                                     sizeof(struct btree_update)))
+               return -BCH_ERR_ENOMEM_btree_interior_update_pool_init;
+
+       return 0;
 }