]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/btree_update_leaf.c
Update bcachefs sources to 3856459b1b bcachefs: bch2_btree_iter_peek_node_and_restart()
[bcachefs-tools-debian] / libbcachefs / btree_update_leaf.c
index 7e9909e2dcaf5ef305effe1bfedd9f74625ee710..c93c132dd815d963360dfe5060dd74925e3ba915 100644 (file)
 #include "btree_iter.h"
 #include "btree_key_cache.h"
 #include "btree_locking.h"
+#include "btree_write_buffer.h"
 #include "buckets.h"
 #include "debug.h"
+#include "errcode.h"
 #include "error.h"
 #include "extent_update.h"
 #include "journal.h"
 #include "journal_reclaim.h"
 #include "keylist.h"
+#include "recovery.h"
+#include "subvolume.h"
 #include "replicas.h"
 
 #include <linux/prefetch.h>
 #include <linux/sort.h>
 #include <trace/events/bcachefs.h>
 
+/*
+ * bch2_btree_path_peek_slot() for a cached iterator might return a key in a
+ * different snapshot:
+ */
+struct bkey_s_c bch2_btree_path_peek_slot_exact(struct btree_path *path, struct bkey *u)
+{
+       struct bkey_s_c k = bch2_btree_path_peek_slot(path, u);
+
+       if (k.k && bpos_eq(path->pos, k.k->p))
+               return k;
+
+       bkey_init(u);
+       u->p = path->pos;
+       return (struct bkey_s_c) { u, NULL };
+}
+
+static void verify_update_old_key(struct btree_trans *trans, struct btree_insert_entry *i)
+{
+#ifdef CONFIG_BCACHEFS_DEBUG
+       struct bch_fs *c = trans->c;
+       struct bkey u;
+       struct bkey_s_c k = bch2_btree_path_peek_slot_exact(i->path, &u);
+
+       if (unlikely(trans->journal_replay_not_finished)) {
+               struct bkey_i *j_k =
+                       bch2_journal_keys_peek_slot(c, i->btree_id, i->level, i->k->k.p);
+
+               if (j_k)
+                       k = bkey_i_to_s_c(j_k);
+       }
+
+       u = *k.k;
+       u.needs_whiteout = i->old_k.needs_whiteout;
+
+       BUG_ON(memcmp(&i->old_k, &u, sizeof(struct bkey)));
+       BUG_ON(i->old_v != k.v);
+#endif
+}
+
+static int __must_check
+bch2_trans_update_by_path(struct btree_trans *, struct btree_path *,
+                         struct bkey_i *, enum btree_update_flags);
+
 static inline int btree_insert_entry_cmp(const struct btree_insert_entry *l,
                                         const struct btree_insert_entry *r)
 {
        return   cmp_int(l->btree_id,   r->btree_id) ?:
+                cmp_int(l->cached,     r->cached) ?:
                 -cmp_int(l->level,     r->level) ?:
                 bpos_cmp(l->k->k.p,    r->k->k.p);
 }
 
+static inline struct btree_path_level *insert_l(struct btree_insert_entry *i)
+{
+       return i->path->l + i->level;
+}
+
 static inline bool same_leaf_as_prev(struct btree_trans *trans,
                                     struct btree_insert_entry *i)
 {
        return i != trans->updates &&
-               iter_l(i[0].iter)->b == iter_l(i[-1].iter)->b;
+               insert_l(&i[0])->b == insert_l(&i[-1])->b;
 }
 
-inline void bch2_btree_node_lock_for_insert(struct btree_trans *trans,
-                                           struct btree_iter *iter,
-                                           struct btree *b)
+static inline bool same_leaf_as_next(struct btree_trans *trans,
+                                    struct btree_insert_entry *i)
 {
-       struct bch_fs *c = trans->c;
-
-       bch2_btree_node_lock_write(b, iter);
+       return i + 1 < trans->updates + trans->nr_updates &&
+               insert_l(&i[0])->b == insert_l(&i[1])->b;
+}
 
-       if (btree_iter_type(iter) == BTREE_ITER_CACHED)
-               return;
+inline void bch2_btree_node_prep_for_write(struct btree_trans *trans,
+                                          struct btree_path *path,
+                                          struct btree *b)
+{
+       struct bch_fs *c = trans->c;
 
        if (unlikely(btree_node_just_written(b)) &&
            bch2_btree_post_write_cleanup(c, b))
-               bch2_btree_iter_reinit_node(iter, b);
+               bch2_trans_node_reinit_iter(trans, b);
 
        /*
         * If the last bset has been written, or if it's gotten too big - start
         * a new bset to insert into:
         */
        if (want_new_bset(c, b))
-               bch2_btree_init_next(trans, iter, b);
+               bch2_btree_init_next(trans, b);
 }
 
 /* Inserting into a given leaf node (last stage of insert): */
 
 /* Handle overwrites and do insert, for non extents: */
-bool bch2_btree_bset_insert_key(struct btree_iter *iter,
+bool bch2_btree_bset_insert_key(struct btree_trans *trans,
+                               struct btree_path *path,
                                struct btree *b,
                                struct btree_node_iter *node_iter,
                                struct bkey_i *insert)
@@ -73,11 +129,10 @@ bool bch2_btree_bset_insert_key(struct btree_iter *iter,
        EBUG_ON(btree_node_just_written(b));
        EBUG_ON(bset_written(b, btree_bset_last(b)));
        EBUG_ON(bkey_deleted(&insert->k) && bkey_val_u64s(&insert->k));
-       EBUG_ON(bpos_cmp(insert->k.p, b->data->min_key) < 0);
-       EBUG_ON(bpos_cmp(insert->k.p, b->data->max_key) > 0);
+       EBUG_ON(bpos_lt(insert->k.p, b->data->min_key));
+       EBUG_ON(bpos_gt(insert->k.p, b->data->max_key));
        EBUG_ON(insert->k.u64s >
-               bch_btree_keys_u64s_remaining(iter->trans->c, b));
-       EBUG_ON(iter->flags & BTREE_ITER_IS_EXTENTS);
+               bch_btree_keys_u64s_remaining(trans->c, b));
 
        k = bch2_btree_node_iter_peek_all(node_iter, b);
        if (k && bkey_cmp_left_packed(b, k, &insert->k.p))
@@ -96,7 +151,7 @@ bool bch2_btree_bset_insert_key(struct btree_iter *iter,
                k->type = KEY_TYPE_deleted;
 
                if (k->needs_whiteout)
-                       push_whiteout(iter->trans->c, b, insert->k.p);
+                       push_whiteout(trans->c, b, insert->k.p);
                k->needs_whiteout = false;
 
                if (k >= btree_bset_last(b)->start) {
@@ -104,7 +159,7 @@ bool bch2_btree_bset_insert_key(struct btree_iter *iter,
                        bch2_bset_delete(b, k, clobber_u64s);
                        goto fix_iter;
                } else {
-                       bch2_btree_iter_fix_key_modified(iter, b, k);
+                       bch2_btree_path_fix_key_modified(trans, b, k);
                }
 
                return true;
@@ -122,7 +177,7 @@ bool bch2_btree_bset_insert_key(struct btree_iter *iter,
                        clobber_u64s = k->u64s;
                        goto overwrite;
                } else {
-                       bch2_btree_iter_fix_key_modified(iter, b, k);
+                       bch2_btree_path_fix_key_modified(trans, b, k);
                }
        }
 
@@ -132,7 +187,7 @@ overwrite:
        new_u64s = k->u64s;
 fix_iter:
        if (clobber_u64s != new_u64s)
-               bch2_btree_node_iter_fix(iter, b, node_iter, k,
+               bch2_btree_node_iter_fix(trans, path, b, node_iter, k,
                                         clobber_u64s, new_u64s);
        return true;
 }
@@ -143,11 +198,32 @@ static int __btree_node_flush(struct journal *j, struct journal_entry_pin *pin,
        struct bch_fs *c = container_of(j, struct bch_fs, journal);
        struct btree_write *w = container_of(pin, struct btree_write, journal);
        struct btree *b = container_of(w, struct btree, writes[i]);
+       struct btree_trans trans;
+       unsigned long old, new, v;
+       unsigned idx = w - b->writes;
+
+       bch2_trans_init(&trans, c, 0, 0);
+
+       btree_node_lock_nopath_nofail(&trans, &b->c, SIX_LOCK_read);
+       v = READ_ONCE(b->flags);
+
+       do {
+               old = new = v;
+
+               if (!(old & (1 << BTREE_NODE_dirty)) ||
+                   !!(old & (1 << BTREE_NODE_write_idx)) != idx ||
+                   w->journal.seq != seq)
+                       break;
+
+               new &= ~BTREE_WRITE_TYPE_MASK;
+               new |= BTREE_WRITE_journal_reclaim;
+               new |= 1 << BTREE_NODE_need_write;
+       } while ((v = cmpxchg(&b->flags, old, new)) != old);
 
-       btree_node_lock_type(c, b, SIX_LOCK_read);
-       bch2_btree_node_write_cond(c, b,
-               (btree_current_write(b) == w && w->journal.seq == seq));
+       btree_node_write_if_need(c, b, SIX_LOCK_read);
        six_unlock_read(&b->c.lock);
+
+       bch2_trans_exit(&trans);
        return 0;
 }
 
@@ -175,32 +251,29 @@ inline void bch2_btree_add_journal_pin(struct bch_fs *c,
 /**
  * btree_insert_key - insert a key one key into a leaf node
  */
-static bool btree_insert_key_leaf(struct btree_trans *trans,
-                                 struct btree_iter *iter,
-                                 struct bkey_i *insert)
+inline void bch2_btree_insert_key_leaf(struct btree_trans *trans,
+                                      struct btree_path *path,
+                                      struct bkey_i *insert,
+                                      u64 journal_seq)
 {
        struct bch_fs *c = trans->c;
-       struct btree *b = iter_l(iter)->b;
+       struct btree *b = path_l(path)->b;
        struct bset_tree *t = bset_tree_last(b);
        struct bset *i = bset(b, t);
        int old_u64s = bset_u64s(t);
        int old_live_u64s = b->nr.live_u64s;
        int live_u64s_added, u64s_added;
 
-       EBUG_ON(!iter->level &&
-               !test_bit(BCH_FS_BTREE_INTERIOR_REPLAY_DONE, &c->flags));
-
-       if (unlikely(!bch2_btree_bset_insert_key(iter, b,
-                                       &iter_l(iter)->iter, insert)))
-               return false;
+       if (unlikely(!bch2_btree_bset_insert_key(trans, path, b,
+                                       &path_l(path)->iter, insert)))
+               return;
 
-       i->journal_seq = cpu_to_le64(max(trans->journal_res.seq,
-                                        le64_to_cpu(i->journal_seq)));
+       i->journal_seq = cpu_to_le64(max(journal_seq, le64_to_cpu(i->journal_seq)));
 
-       bch2_btree_add_journal_pin(c, b, trans->journal_res.seq);
+       bch2_btree_add_journal_pin(c, b, journal_seq);
 
        if (unlikely(!btree_node_dirty(b)))
-               set_btree_node_dirty(c, b);
+               set_btree_node_dirty_acct(c, b);
 
        live_u64s_added = (int) b->nr.live_u64s - old_live_u64s;
        u64s_added = (int) bset_u64s(t) - old_u64s;
@@ -212,10 +285,13 @@ static bool btree_insert_key_leaf(struct btree_trans *trans,
 
        if (u64s_added > live_u64s_added &&
            bch2_maybe_compact_whiteouts(c, b))
-               bch2_btree_iter_reinit_node(iter, b);
+               bch2_trans_node_reinit_iter(trans, b);
+}
 
-       trace_btree_insert_key(c, b, insert);
-       return true;
+static void btree_insert_key_leaf(struct btree_trans *trans,
+                                 struct btree_insert_entry *insert)
+{
+       bch2_btree_insert_key_leaf(trans, insert->path, insert->k, trans->journal_res.seq);
 }
 
 /* Cached btree updates: */
@@ -225,13 +301,19 @@ static bool btree_insert_key_leaf(struct btree_trans *trans,
 static inline void btree_insert_entry_checks(struct btree_trans *trans,
                                             struct btree_insert_entry *i)
 {
-       BUG_ON(bpos_cmp(i->k->k.p, i->iter->real_pos));
-       BUG_ON(i->level         != i->iter->level);
-       BUG_ON(i->btree_id      != i->iter->btree_id);
+       BUG_ON(!bpos_eq(i->k->k.p, i->path->pos));
+       BUG_ON(i->cached        != i->path->cached);
+       BUG_ON(i->level         != i->path->level);
+       BUG_ON(i->btree_id      != i->path->btree_id);
+       EBUG_ON(!i->level &&
+               !(i->flags & BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) &&
+               test_bit(JOURNAL_REPLAY_DONE, &trans->c->journal.flags) &&
+               i->k->k.p.snapshot &&
+               bch2_snapshot_internal_node(trans->c, i->k->k.p.snapshot));
 }
 
 static noinline int
-bch2_trans_journal_preres_get_cold(struct btree_trans *trans, unsigned u64s,
+bch2_trans_journal_preres_get_cold(struct btree_trans *trans, unsigned flags,
                                   unsigned long trace_ip)
 {
        struct bch_fs *c = trans->c;
@@ -240,62 +322,70 @@ bch2_trans_journal_preres_get_cold(struct btree_trans *trans, unsigned u64s,
        bch2_trans_unlock(trans);
 
        ret = bch2_journal_preres_get(&c->journal,
-                       &trans->journal_preres, u64s, 0);
+                       &trans->journal_preres,
+                       trans->journal_preres_u64s,
+                       (flags & JOURNAL_WATERMARK_MASK));
        if (ret)
                return ret;
 
-       if (!bch2_trans_relock(trans)) {
-               trace_trans_restart_journal_preres_get(trans->ip, trace_ip);
-               return -EINTR;
+       ret = bch2_trans_relock(trans);
+       if (ret) {
+               trace_and_count(c, trans_restart_journal_preres_get, trans, trace_ip, 0);
+               return ret;
        }
 
        return 0;
 }
 
-static inline int bch2_trans_journal_res_get(struct btree_trans *trans,
-                                            unsigned flags)
+static __always_inline int bch2_trans_journal_res_get(struct btree_trans *trans,
+                                                     unsigned flags)
 {
-       struct bch_fs *c = trans->c;
-       int ret;
-
-       if (trans->flags & BTREE_INSERT_JOURNAL_RESERVED)
-               flags |= JOURNAL_RES_GET_RESERVED;
+       return bch2_journal_res_get(&trans->c->journal, &trans->journal_res,
+                                   trans->journal_u64s, flags);
+}
 
-       ret = bch2_journal_res_get(&c->journal, &trans->journal_res,
-                                  trans->journal_u64s, flags);
+#define JSET_ENTRY_LOG_U64s            4
 
-       return ret == -EAGAIN ? BTREE_INSERT_NEED_JOURNAL_RES : ret;
+static noinline void journal_transaction_name(struct btree_trans *trans)
+{
+       struct bch_fs *c = trans->c;
+       struct journal *j = &c->journal;
+       struct jset_entry *entry =
+               bch2_journal_add_entry(j, &trans->journal_res,
+                                      BCH_JSET_ENTRY_log, 0, 0,
+                                      JSET_ENTRY_LOG_U64s);
+       struct jset_entry_log *l =
+               container_of(entry, struct jset_entry_log, entry);
+
+       strncpy(l->d, trans->fn, JSET_ENTRY_LOG_U64s * sizeof(u64));
 }
 
-static enum btree_insert_ret
-btree_key_can_insert(struct btree_trans *trans,
-                    struct btree_iter *iter,
-                    unsigned u64s)
+static inline int btree_key_can_insert(struct btree_trans *trans,
+                                      struct btree *b, unsigned u64s)
 {
        struct bch_fs *c = trans->c;
-       struct btree *b = iter_l(iter)->b;
 
        if (!bch2_btree_node_insert_fits(c, b, u64s))
-               return BTREE_INSERT_BTREE_NODE_FULL;
+               return -BCH_ERR_btree_insert_btree_node_full;
 
-       return BTREE_INSERT_OK;
+       return 0;
 }
 
-static enum btree_insert_ret
-btree_key_can_insert_cached(struct btree_trans *trans,
-                           struct btree_iter *iter,
-                           unsigned u64s)
+static int btree_key_can_insert_cached(struct btree_trans *trans, unsigned flags,
+                                      struct btree_path *path, unsigned u64s)
 {
-       struct bkey_cached *ck = (void *) iter->l[0].b;
+       struct bch_fs *c = trans->c;
+       struct bkey_cached *ck = (void *) path->l[0].b;
+       struct btree_insert_entry *i;
        unsigned new_u64s;
        struct bkey_i *new_k;
 
-       BUG_ON(iter->level);
+       EBUG_ON(path->level);
 
        if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
-           bch2_btree_key_cache_must_wait(trans->c) &&
-           !(trans->flags & BTREE_INSERT_JOURNAL_RECLAIM))
-               return BTREE_INSERT_NEED_JOURNAL_RECLAIM;
+           bch2_btree_key_cache_must_wait(c) &&
+           !(flags & BTREE_INSERT_JOURNAL_RECLAIM))
+               return -BCH_ERR_btree_insert_need_journal_reclaim;
 
        /*
         * bch2_varint_decode can read past the end of the buffer by at most 7
@@ -304,83 +394,224 @@ btree_key_can_insert_cached(struct btree_trans *trans,
        u64s += 1;
 
        if (u64s <= ck->u64s)
-               return BTREE_INSERT_OK;
+               return 0;
 
        new_u64s        = roundup_pow_of_two(u64s);
        new_k           = krealloc(ck->k, new_u64s * sizeof(u64), GFP_NOFS);
-       if (!new_k)
+       if (!new_k) {
+               bch_err(c, "error allocating memory for key cache key, btree %s u64s %u",
+                       bch2_btree_ids[path->btree_id], new_u64s);
                return -ENOMEM;
+       }
+
+       trans_for_each_update(trans, i)
+               if (i->old_v == &ck->k->v)
+                       i->old_v = &new_k->v;
 
        ck->u64s        = new_u64s;
        ck->k           = new_k;
-       return BTREE_INSERT_OK;
+       return 0;
 }
 
-static inline void do_btree_insert_one(struct btree_trans *trans,
-                                      struct btree_insert_entry *i)
+/* Triggers: */
+
+static int run_one_mem_trigger(struct btree_trans *trans,
+                              struct btree_insert_entry *i,
+                              unsigned flags)
 {
-       struct bch_fs *c = trans->c;
-       struct journal *j = &c->journal;
-       bool did_work;
+       struct bkey_s_c old = { &i->old_k, i->old_v };
+       struct bkey_i *new = i->k;
+       int ret;
+
+       verify_update_old_key(trans, i);
 
-       EBUG_ON(trans->journal_res.ref !=
-               !(trans->flags & BTREE_INSERT_JOURNAL_REPLAY));
+       if (unlikely(flags & BTREE_TRIGGER_NORUN))
+               return 0;
 
-       i->k->k.needs_whiteout = false;
+       if (!btree_node_type_needs_gc(i->btree_id))
+               return 0;
 
-       did_work = (btree_iter_type(i->iter) != BTREE_ITER_CACHED)
-               ? btree_insert_key_leaf(trans, i->iter, i->k)
-               : bch2_btree_insert_key_cached(trans, i->iter, i->k);
-       if (!did_work)
-               return;
+       if (bch2_bkey_ops[old.k->type].atomic_trigger ==
+           bch2_bkey_ops[i->k->k.type].atomic_trigger &&
+           ((1U << old.k->type) & BTREE_TRIGGER_WANTS_OLD_AND_NEW)) {
+               ret   = bch2_mark_key(trans, i->btree_id, i->level,
+                               old, bkey_i_to_s_c(new),
+                               BTREE_TRIGGER_INSERT|BTREE_TRIGGER_OVERWRITE|flags);
+       } else {
+               struct bkey             _deleted = KEY(0, 0, 0);
+               struct bkey_s_c         deleted = (struct bkey_s_c) { &_deleted, NULL };
 
-       if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
-               bch2_journal_add_keys(j, &trans->journal_res,
-                                     i->btree_id,
-                                     i->level,
-                                     i->k);
+               _deleted.p = i->path->pos;
 
-               bch2_journal_set_has_inode(j, &trans->journal_res,
-                                          i->k->k.p.inode);
+               ret   = bch2_mark_key(trans, i->btree_id, i->level,
+                               deleted, bkey_i_to_s_c(new),
+                               BTREE_TRIGGER_INSERT|flags) ?:
+                       bch2_mark_key(trans, i->btree_id, i->level,
+                               old, deleted,
+                               BTREE_TRIGGER_OVERWRITE|flags);
+       }
 
-               if (trans->journal_seq)
-                       *trans->journal_seq = trans->journal_res.seq;
+       return ret;
+}
+
+static int run_one_trans_trigger(struct btree_trans *trans, struct btree_insert_entry *i,
+                                bool overwrite)
+{
+       /*
+        * Transactional triggers create new btree_insert_entries, so we can't
+        * pass them a pointer to a btree_insert_entry, that memory is going to
+        * move:
+        */
+       struct bkey old_k = i->old_k;
+       struct bkey_s_c old = { &old_k, i->old_v };
+
+       verify_update_old_key(trans, i);
+
+       if ((i->flags & BTREE_TRIGGER_NORUN) ||
+           !(BTREE_NODE_TYPE_HAS_TRANS_TRIGGERS & (1U << i->bkey_type)))
+               return 0;
+
+       if (!i->insert_trigger_run &&
+           !i->overwrite_trigger_run &&
+           bch2_bkey_ops[old.k->type].trans_trigger ==
+           bch2_bkey_ops[i->k->k.type].trans_trigger &&
+           ((1U << old.k->type) & BTREE_TRIGGER_WANTS_OLD_AND_NEW)) {
+               i->overwrite_trigger_run = true;
+               i->insert_trigger_run = true;
+               return bch2_trans_mark_key(trans, i->btree_id, i->level, old, i->k,
+                                          BTREE_TRIGGER_INSERT|
+                                          BTREE_TRIGGER_OVERWRITE|
+                                          i->flags) ?: 1;
+       } else if (overwrite && !i->overwrite_trigger_run) {
+               i->overwrite_trigger_run = true;
+               return bch2_trans_mark_old(trans, i->btree_id, i->level, old, i->flags) ?: 1;
+       } else if (!overwrite && !i->insert_trigger_run) {
+               i->insert_trigger_run = true;
+               return bch2_trans_mark_new(trans, i->btree_id, i->level, i->k, i->flags) ?: 1;
+       } else {
+               return 0;
+       }
+}
+
+static int run_btree_triggers(struct btree_trans *trans, enum btree_id btree_id,
+                             struct btree_insert_entry *btree_id_start)
+{
+       struct btree_insert_entry *i;
+       bool trans_trigger_run;
+       int ret, overwrite;
+
+       for (overwrite = 1; overwrite >= 0; --overwrite) {
+
+               /*
+                * Running triggers will append more updates to the list of updates as
+                * we're walking it:
+                */
+               do {
+                       trans_trigger_run = false;
+
+                       for (i = btree_id_start;
+                            i < trans->updates + trans->nr_updates && i->btree_id <= btree_id;
+                            i++) {
+                               if (i->btree_id != btree_id)
+                                       continue;
+
+                               ret = run_one_trans_trigger(trans, i, overwrite);
+                               if (ret < 0)
+                                       return ret;
+                               if (ret)
+                                       trans_trigger_run = true;
+                       }
+               } while (trans_trigger_run);
+       }
+
+       return 0;
+}
+
+static int bch2_trans_commit_run_triggers(struct btree_trans *trans)
+{
+       struct btree_insert_entry *i = NULL, *btree_id_start = trans->updates;
+       unsigned btree_id = 0;
+       int ret = 0;
+
+       /*
+        *
+        * For a given btree, this algorithm runs insert triggers before
+        * overwrite triggers: this is so that when extents are being moved
+        * (e.g. by FALLOCATE_FL_INSERT_RANGE), we don't drop references before
+        * they are re-added.
+        */
+       for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
+               if (btree_id == BTREE_ID_alloc)
+                       continue;
+
+               while (btree_id_start < trans->updates + trans->nr_updates &&
+                      btree_id_start->btree_id < btree_id)
+                       btree_id_start++;
+
+               ret = run_btree_triggers(trans, btree_id, btree_id_start);
+               if (ret)
+                       return ret;
+       }
+
+       trans_for_each_update(trans, i) {
+               if (i->btree_id > BTREE_ID_alloc)
+                       break;
+               if (i->btree_id == BTREE_ID_alloc) {
+                       ret = run_btree_triggers(trans, BTREE_ID_alloc, i);
+                       if (ret)
+                               return ret;
+                       break;
+               }
        }
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+       trans_for_each_update(trans, i)
+               BUG_ON(!(i->flags & BTREE_TRIGGER_NORUN) &&
+                      (BTREE_NODE_TYPE_HAS_TRANS_TRIGGERS & (1U << i->bkey_type)) &&
+                      (!i->insert_trigger_run || !i->overwrite_trigger_run));
+#endif
+       return 0;
 }
 
-static noinline void bch2_trans_mark_gc(struct btree_trans *trans)
+static noinline int bch2_trans_commit_run_gc_triggers(struct btree_trans *trans)
 {
        struct bch_fs *c = trans->c;
        struct btree_insert_entry *i;
+       int ret = 0;
 
        trans_for_each_update(trans, i) {
                /*
                 * XXX: synchronization of cached update triggers with gc
+                * XXX: synchronization of interior node updates with gc
                 */
-               BUG_ON(btree_iter_type(i->iter) == BTREE_ITER_CACHED);
+               BUG_ON(i->cached || i->level);
 
-               if (gc_visited(c, gc_pos_btree_node(i->iter->l[0].b)))
-                       bch2_mark_update(trans, i->iter, i->k,
-                                        i->flags|BTREE_TRIGGER_GC);
+               if (gc_visited(c, gc_pos_btree_node(insert_l(i)->b))) {
+                       ret = run_one_mem_trigger(trans, i, i->flags|BTREE_TRIGGER_GC);
+                       if (ret)
+                               break;
+               }
        }
+
+       return ret;
 }
 
 static inline int
-bch2_trans_commit_write_locked(struct btree_trans *trans,
+bch2_trans_commit_write_locked(struct btree_trans *trans, unsigned flags,
                               struct btree_insert_entry **stopped_at,
                               unsigned long trace_ip)
 {
        struct bch_fs *c = trans->c;
        struct btree_insert_entry *i;
+       struct btree_write_buffered_key *wb;
        struct btree_trans_commit_hook *h;
        unsigned u64s = 0;
        bool marking = false;
        int ret;
 
        if (race_fault()) {
-               trace_trans_restart_fault_inject(trans->ip, trace_ip);
-               trans->restarted = true;
-               return -EINTR;
+               trace_and_count(c, trans_restart_fault_inject, trans, trace_ip);
+               return btree_trans_restart_nounlock(trans, BCH_ERR_transaction_restart_fault_inject);
        }
 
        /*
@@ -405,9 +636,9 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
                        u64s = 0;
 
                u64s += i->k->k.u64s;
-               ret = btree_iter_type(i->iter) != BTREE_ITER_CACHED
-                       ? btree_key_can_insert(trans, i->iter, u64s)
-                       : btree_key_can_insert_cached(trans, i->iter, u64s);
+               ret = !i->cached
+                       ? btree_key_can_insert(trans, insert_l(i)->b, u64s)
+                       : btree_key_can_insert_cached(trans, flags, i->path, u64s);
                if (ret) {
                        *stopped_at = i;
                        return ret;
@@ -417,45 +648,34 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
                        marking = true;
        }
 
-       if (marking) {
-               percpu_down_read(&c->mark_lock);
-       }
-
-       /* Must be called under mark_lock: */
-       if (marking && trans->fs_usage_deltas &&
-           !bch2_replicas_delta_list_marked(c, trans->fs_usage_deltas)) {
-               ret = BTREE_INSERT_NEED_MARK_REPLICAS;
-               goto err;
-       }
+       if (trans->nr_wb_updates &&
+           trans->nr_wb_updates + c->btree_write_buffer.state.nr > c->btree_write_buffer.size)
+               return -BCH_ERR_btree_insert_need_flush_buffer;
 
        /*
         * Don't get journal reservation until after we know insert will
         * succeed:
         */
-       if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
+       if (likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY))) {
                ret = bch2_trans_journal_res_get(trans,
+                               (flags & JOURNAL_WATERMARK_MASK)|
                                JOURNAL_RES_GET_NONBLOCK);
                if (ret)
-                       goto err;
+                       return ret;
+
+               if (unlikely(trans->journal_transaction_names))
+                       journal_transaction_name(trans);
        } else {
                trans->journal_res.seq = c->journal.replay_journal_seq;
        }
 
-       if (unlikely(trans->extra_journal_entry_u64s)) {
-               memcpy_u64s_small(journal_res_entry(&c->journal, &trans->journal_res),
-                                 trans->extra_journal_entries,
-                                 trans->extra_journal_entry_u64s);
-
-               trans->journal_res.offset       += trans->extra_journal_entry_u64s;
-               trans->journal_res.u64s         -= trans->extra_journal_entry_u64s;
-       }
-
        /*
         * Not allowed to fail after we've gotten our journal reservation - we
         * have to use it:
         */
 
-       if (!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY)) {
+       if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG) &&
+           !(flags & BTREE_INSERT_JOURNAL_REPLAY)) {
                if (bch2_journal_seq_verify)
                        trans_for_each_update(trans, i)
                                i->k->k.version.lo = trans->journal_res.seq;
@@ -464,154 +684,240 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
                                i->k->k.version = MAX_VERSION;
        }
 
-       trans_for_each_update(trans, i)
-               if (BTREE_NODE_TYPE_HAS_MEM_TRIGGERS & (1U << i->bkey_type))
-                       bch2_mark_update(trans, i->iter, i->k,
-                                        i->flags);
+       if (trans->fs_usage_deltas &&
+           bch2_trans_fs_usage_apply(trans, trans->fs_usage_deltas))
+               return -BCH_ERR_btree_insert_need_mark_replicas;
 
-       if (marking && trans->fs_usage_deltas)
-               bch2_trans_fs_usage_apply(trans, trans->fs_usage_deltas);
+       if (trans->nr_wb_updates) {
+               EBUG_ON(flags & BTREE_INSERT_JOURNAL_REPLAY);
 
-       if (unlikely(c->gc_pos.phase))
-               bch2_trans_mark_gc(trans);
+               ret = bch2_btree_insert_keys_write_buffer(trans);
+               if (ret)
+                       goto revert_fs_usage;
+       }
 
        trans_for_each_update(trans, i)
-               do_btree_insert_one(trans, i);
-err:
-       if (marking) {
-               percpu_up_read(&c->mark_lock);
+               if (BTREE_NODE_TYPE_HAS_MEM_TRIGGERS & (1U << i->bkey_type)) {
+                       ret = run_one_mem_trigger(trans, i, i->flags);
+                       if (ret)
+                               goto fatal_err;
+               }
+
+       if (unlikely(c->gc_pos.phase)) {
+               ret = bch2_trans_commit_run_gc_triggers(trans);
+               if  (ret)
+                       goto fatal_err;
+       }
+
+       if (unlikely(trans->extra_journal_entries.nr)) {
+               memcpy_u64s_small(journal_res_entry(&c->journal, &trans->journal_res),
+                                 trans->extra_journal_entries.data,
+                                 trans->extra_journal_entries.nr);
+
+               trans->journal_res.offset       += trans->extra_journal_entries.nr;
+               trans->journal_res.u64s         -= trans->extra_journal_entries.nr;
+       }
+
+       if (likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY))) {
+               struct journal *j = &c->journal;
+               struct jset_entry *entry;
+
+               trans_for_each_update(trans, i) {
+                       if (i->key_cache_already_flushed)
+                               continue;
+
+                       if (i->flags & BTREE_UPDATE_NOJOURNAL)
+                               continue;
+
+                       verify_update_old_key(trans, i);
+
+                       if (trans->journal_transaction_names) {
+                               entry = bch2_journal_add_entry(j, &trans->journal_res,
+                                                      BCH_JSET_ENTRY_overwrite,
+                                                      i->btree_id, i->level,
+                                                      i->old_k.u64s);
+                               bkey_reassemble(&entry->start[0],
+                                               (struct bkey_s_c) { &i->old_k, i->old_v });
+                       }
+
+                       entry = bch2_journal_add_entry(j, &trans->journal_res,
+                                              BCH_JSET_ENTRY_btree_keys,
+                                              i->btree_id, i->level,
+                                              i->k->k.u64s);
+                       bkey_copy(&entry->start[0], i->k);
+               }
+
+               trans_for_each_wb_update(trans, wb) {
+                       entry = bch2_journal_add_entry(j, &trans->journal_res,
+                                              BCH_JSET_ENTRY_btree_keys,
+                                              wb->btree, 0,
+                                              wb->k.k.u64s);
+                       bkey_copy(&entry->start[0], &wb->k);
+               }
+
+               if (trans->journal_seq)
+                       *trans->journal_seq = trans->journal_res.seq;
+       }
+
+       trans_for_each_update(trans, i) {
+               i->k->k.needs_whiteout = false;
+
+               if (!i->cached)
+                       btree_insert_key_leaf(trans, i);
+               else if (!i->key_cache_already_flushed)
+                       bch2_btree_insert_key_cached(trans, flags, i->path, i->k);
+               else {
+                       bch2_btree_key_cache_drop(trans, i->path);
+                       btree_path_set_dirty(i->path, BTREE_ITER_NEED_TRAVERSE);
+               }
        }
 
+       return 0;
+fatal_err:
+       bch2_fatal_error(c);
+revert_fs_usage:
+       if (trans->fs_usage_deltas)
+               bch2_trans_fs_usage_revert(trans, trans->fs_usage_deltas);
        return ret;
 }
 
-static noinline int maybe_do_btree_merge(struct btree_trans *trans, struct btree_iter *iter)
+static noinline int trans_lock_write_fail(struct btree_trans *trans, struct btree_insert_entry *i)
 {
-       struct btree_insert_entry *i;
-       struct btree *b = iter_l(iter)->b;
-       struct bkey_s_c old;
-       int u64s_delta = 0;
-       int ret;
+       while (--i >= trans->updates) {
+               if (same_leaf_as_prev(trans, i))
+                       continue;
 
-       /*
-        * Inserting directly into interior nodes is an uncommon operation with
-        * various weird edge cases: also, a lot of things about
-        * BTREE_ITER_NODES iters need to be audited
-        */
-       if (unlikely(btree_iter_type(iter) != BTREE_ITER_KEYS))
-               return 0;
+               bch2_btree_node_unlock_write(trans, i->path, insert_l(i)->b);
+       }
+
+       trace_and_count(trans->c, trans_restart_would_deadlock_write, trans);
+       return btree_trans_restart(trans, BCH_ERR_transaction_restart_would_deadlock_write);
+}
 
-       BUG_ON(iter->level);
+static inline int trans_lock_write(struct btree_trans *trans)
+{
+       struct btree_insert_entry *i;
 
        trans_for_each_update(trans, i) {
-               if (iter_l(i->iter)->b != b)
+               if (same_leaf_as_prev(trans, i))
                        continue;
 
-               old = bch2_btree_iter_peek_slot(i->iter);
-               ret = bkey_err(old);
-               if (ret)
-                       return ret;
+               if (bch2_btree_node_lock_write(trans, i->path, &insert_l(i)->b->c))
+                       return trans_lock_write_fail(trans, i);
 
-               u64s_delta += !bkey_deleted(&i->k->k) ? i->k->k.u64s : 0;
-               u64s_delta -= !bkey_deleted(old.k) ? old.k->u64s : 0;
+               if (!i->cached)
+                       bch2_btree_node_prep_for_write(trans, i->path, insert_l(i)->b);
        }
 
-       if (u64s_delta > 0)
-               return 0;
+       return 0;
+}
+
+static noinline void bch2_drop_overwrites_from_journal(struct btree_trans *trans)
+{
+       struct btree_insert_entry *i;
+       struct btree_write_buffered_key *wb;
+
+       trans_for_each_update(trans, i)
+               bch2_journal_key_overwritten(trans->c, i->btree_id, i->level, i->k->k.p);
+
+       trans_for_each_wb_update(trans, wb)
+               bch2_journal_key_overwritten(trans->c, wb->btree, 0, wb->k.k.p);
+}
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+static noinline int bch2_trans_commit_bkey_invalid(struct btree_trans *trans, unsigned flags,
+                                                  struct btree_insert_entry *i,
+                                                  struct printbuf *err)
+{
+       struct bch_fs *c = trans->c;
+       int rw = (flags & BTREE_INSERT_JOURNAL_REPLAY) ? READ : WRITE;
+
+       printbuf_reset(err);
+       prt_printf(err, "invalid bkey on insert from %s -> %ps",
+                  trans->fn, (void *) i->ip_allocated);
+       prt_newline(err);
+       printbuf_indent_add(err, 2);
 
-       return bch2_foreground_maybe_merge(trans, iter,
-                               iter->level, trans->flags);
+       bch2_bkey_val_to_text(err, c, bkey_i_to_s_c(i->k));
+       prt_newline(err);
+
+       bch2_bkey_invalid(c, bkey_i_to_s_c(i->k),
+                         i->bkey_type, rw, err);
+       bch2_print_string_as_lines(KERN_ERR, err->buf);
+
+       bch2_inconsistent_error(c);
+       bch2_dump_trans_updates(trans);
+       printbuf_exit(err);
+
+       return -EINVAL;
 }
+#endif
 
 /*
  * Get journal reservation, take write locks, and attempt to do btree update(s):
  */
-static inline int do_bch2_trans_commit(struct btree_trans *trans,
+static inline int do_bch2_trans_commit(struct btree_trans *trans, unsigned flags,
                                       struct btree_insert_entry **stopped_at,
                                       unsigned long trace_ip)
 {
        struct bch_fs *c = trans->c;
        struct btree_insert_entry *i;
-       struct btree_iter *iter;
-       int ret;
+       int ret, u64s_delta = 0;
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+       struct printbuf buf = PRINTBUF;
 
        trans_for_each_update(trans, i) {
-               struct btree *b;
+               int rw = (flags & BTREE_INSERT_JOURNAL_REPLAY) ? READ : WRITE;
 
-               BUG_ON(!btree_node_intent_locked(i->iter, i->level));
+               if (unlikely(bch2_bkey_invalid(c, bkey_i_to_s_c(i->k),
+                                              i->bkey_type, rw, &buf)))
+                       return bch2_trans_commit_bkey_invalid(trans, flags, i, &buf);
+               btree_insert_entry_checks(trans, i);
+       }
+       printbuf_exit(&buf);
+#endif
 
-               if (btree_iter_type(i->iter) == BTREE_ITER_CACHED)
+       trans_for_each_update(trans, i) {
+               if (i->cached)
                        continue;
 
-               b = iter_l(i->iter)->b;
-               if (b->sib_u64s[0] < c->btree_foreground_merge_threshold ||
-                   b->sib_u64s[1] < c->btree_foreground_merge_threshold) {
-                       ret = maybe_do_btree_merge(trans, i->iter);
-                       if (unlikely(ret))
-                               return ret;
+               u64s_delta += !bkey_deleted(&i->k->k) ? i->k->k.u64s : 0;
+               u64s_delta -= i->old_btree_u64s;
+
+               if (!same_leaf_as_next(trans, i)) {
+                       if (u64s_delta <= 0) {
+                               ret = bch2_foreground_maybe_merge(trans, i->path,
+                                                       i->level, flags);
+                               if (unlikely(ret))
+                                       return ret;
+                       }
+
+                       u64s_delta = 0;
                }
        }
 
-       trans_for_each_update(trans, i)
-               BUG_ON(!btree_node_intent_locked(i->iter, i->level));
-
        ret = bch2_journal_preres_get(&c->journal,
                        &trans->journal_preres, trans->journal_preres_u64s,
-                       JOURNAL_RES_GET_NONBLOCK|
-                       ((trans->flags & BTREE_INSERT_JOURNAL_RESERVED)
-                        ? JOURNAL_RES_GET_RESERVED : 0));
-       if (unlikely(ret == -EAGAIN))
-               ret = bch2_trans_journal_preres_get_cold(trans,
-                                               trans->journal_preres_u64s, trace_ip);
+                       (flags & JOURNAL_WATERMARK_MASK)|JOURNAL_RES_GET_NONBLOCK);
+       if (unlikely(ret == -BCH_ERR_journal_preres_get_blocked))
+               ret = bch2_trans_journal_preres_get_cold(trans, flags, trace_ip);
        if (unlikely(ret))
                return ret;
 
-       /*
-        * Can't be holding any read locks when we go to take write locks:
-        * another thread could be holding an intent lock on the same node we
-        * have a read lock on, and it'll block trying to take a write lock
-        * (because we hold a read lock) and it could be blocking us by holding
-        * its own read lock (while we're trying to to take write locks).
-        *
-        * note - this must be done after bch2_trans_journal_preres_get_cold()
-        * or anything else that might call bch2_trans_relock(), since that
-        * would just retake the read locks:
-        */
-       trans_for_each_iter(trans, iter)
-               if (iter->nodes_locked != iter->nodes_intent_locked &&
-                   !bch2_btree_iter_upgrade(iter, 1)) {
-                       trace_trans_restart_upgrade(trans->ip, trace_ip,
-                                                   iter->btree_id,
-                                                   &iter->real_pos);
-                       trans->restarted = true;
-                       return -EINTR;
-               }
-
-       trans_for_each_update(trans, i) {
-               const char *invalid = bch2_bkey_invalid(c,
-                               bkey_i_to_s_c(i->k), i->bkey_type);
-               if (invalid) {
-                       char buf[200];
-
-                       bch2_bkey_val_to_text(&PBUF(buf), c, bkey_i_to_s_c(i->k));
-                       bch_err(c, "invalid bkey %s on insert: %s\n", buf, invalid);
-                       bch2_fatal_error(c);
-               }
-               btree_insert_entry_checks(trans, i);
-       }
-       bch2_btree_trans_verify_locks(trans);
+       ret = trans_lock_write(trans);
+       if (unlikely(ret))
+               return ret;
 
-       trans_for_each_update(trans, i)
-               if (!same_leaf_as_prev(trans, i))
-                       bch2_btree_node_lock_for_insert(trans, i->iter,
-                                       iter_l(i->iter)->b);
+       ret = bch2_trans_commit_write_locked(trans, flags, stopped_at, trace_ip);
 
-       ret = bch2_trans_commit_write_locked(trans, stopped_at, trace_ip);
+       if (!ret && unlikely(trans->journal_replay_not_finished))
+               bch2_drop_overwrites_from_journal(trans);
 
        trans_for_each_update(trans, i)
                if (!same_leaf_as_prev(trans, i))
-                       bch2_btree_node_unlock_write_inlined(iter_l(i->iter)->b,
-                                                            i->iter);
+                       bch2_btree_node_unlock_write_inlined(trans, i->path,
+                                                       insert_l(i)->b);
 
        if (!ret && trans->journal_pin)
                bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
@@ -642,421 +948,776 @@ static int journal_reclaim_wait_done(struct bch_fs *c)
 }
 
 static noinline
-int bch2_trans_commit_error(struct btree_trans *trans,
+int bch2_trans_commit_error(struct btree_trans *trans, unsigned flags,
                            struct btree_insert_entry *i,
                            int ret, unsigned long trace_ip)
 {
        struct bch_fs *c = trans->c;
 
        switch (ret) {
-       case BTREE_INSERT_BTREE_NODE_FULL:
-               ret = bch2_btree_split_leaf(trans, i->iter, trans->flags);
-               if (!ret)
-                       return 0;
-
-               if (ret == -EINTR)
-                       trace_trans_restart_btree_node_split(trans->ip, trace_ip,
-                                                            i->iter->btree_id,
-                                                            &i->iter->real_pos);
+       case -BCH_ERR_btree_insert_btree_node_full:
+               ret = bch2_btree_split_leaf(trans, i->path, flags);
+               if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+                       trace_and_count(c, trans_restart_btree_node_split, trans, trace_ip, i->path);
                break;
-       case BTREE_INSERT_NEED_MARK_REPLICAS:
+       case -BCH_ERR_btree_insert_need_mark_replicas:
                bch2_trans_unlock(trans);
 
                ret = bch2_replicas_delta_list_mark(c, trans->fs_usage_deltas);
                if (ret)
                        break;
 
-               if (bch2_trans_relock(trans))
-                       return 0;
-
-               trace_trans_restart_mark_replicas(trans->ip, trace_ip);
-               ret = -EINTR;
+               ret = bch2_trans_relock(trans);
+               if (ret)
+                       trace_and_count(c, trans_restart_mark_replicas, trans, trace_ip);
                break;
-       case BTREE_INSERT_NEED_JOURNAL_RES:
+       case -BCH_ERR_journal_res_get_blocked:
                bch2_trans_unlock(trans);
 
-               if ((trans->flags & BTREE_INSERT_JOURNAL_RECLAIM) &&
-                   !(trans->flags & BTREE_INSERT_JOURNAL_RESERVED)) {
-                       trans->restarted = true;
-                       ret = -EAGAIN;
+               if ((flags & BTREE_INSERT_JOURNAL_RECLAIM) &&
+                   !(flags & JOURNAL_WATERMARK_reserved)) {
+                       ret = -BCH_ERR_journal_reclaim_would_deadlock;
                        break;
                }
 
-               ret = bch2_trans_journal_res_get(trans, JOURNAL_RES_GET_CHECK);
+               ret = bch2_trans_journal_res_get(trans,
+                                       (flags & JOURNAL_WATERMARK_MASK)|
+                                       JOURNAL_RES_GET_CHECK);
                if (ret)
                        break;
 
-               if (bch2_trans_relock(trans))
-                       return 0;
-
-               trace_trans_restart_journal_res_get(trans->ip, trace_ip);
-               ret = -EINTR;
+               ret = bch2_trans_relock(trans);
+               if (ret)
+                       trace_and_count(c, trans_restart_journal_res_get, trans, trace_ip);
                break;
-       case BTREE_INSERT_NEED_JOURNAL_RECLAIM:
+       case -BCH_ERR_btree_insert_need_journal_reclaim:
                bch2_trans_unlock(trans);
 
-               trace_trans_blocked_journal_reclaim(trans->ip, trace_ip);
+               trace_and_count(c, trans_blocked_journal_reclaim, trans, trace_ip);
 
                wait_event_freezable(c->journal.reclaim_wait,
                                     (ret = journal_reclaim_wait_done(c)));
                if (ret < 0)
                        break;
 
-               if (bch2_trans_relock(trans))
-                       return 0;
+               ret = bch2_trans_relock(trans);
+               if (ret)
+                       trace_and_count(c, trans_restart_journal_reclaim, trans, trace_ip);
+               break;
+       case -BCH_ERR_btree_insert_need_flush_buffer: {
+               struct btree_write_buffer *wb = &c->btree_write_buffer;
+
+               ret = 0;
+
+               if (wb->state.nr > wb->size * 3 / 4) {
+                       bch2_trans_reset_updates(trans);
+                       bch2_trans_unlock(trans);
+
+                       mutex_lock(&wb->flush_lock);
+
+                       if (wb->state.nr > wb->size * 3 / 4)
+                               ret = __bch2_btree_write_buffer_flush(trans,
+                                               flags|BTREE_INSERT_NOCHECK_RW, true);
+                       else
+                               mutex_unlock(&wb->flush_lock);
 
-               trace_trans_restart_journal_reclaim(trans->ip, trace_ip);
-               ret = -EINTR;
+                       if (!ret) {
+                               trace_and_count(c, trans_restart_write_buffer_flush, trans, _THIS_IP_);
+                               ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_write_buffer_flush);
+                       }
+               }
                break;
+       }
        default:
                BUG_ON(ret >= 0);
                break;
        }
 
-       BUG_ON((ret == EINTR || ret == -EAGAIN) && !trans->restarted);
-       BUG_ON(ret == -ENOSPC && (trans->flags & BTREE_INSERT_NOFAIL));
+       BUG_ON(bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted);
+
+       bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOSPC) &&
+                               !(flags & BTREE_INSERT_NOWAIT) &&
+                               (flags & BTREE_INSERT_NOFAIL), c,
+               "%s: incorrectly got %s\n", __func__, bch2_err_str(ret));
 
        return ret;
 }
 
 static noinline int
-bch2_trans_commit_get_rw_cold(struct btree_trans *trans)
+bch2_trans_commit_get_rw_cold(struct btree_trans *trans, unsigned flags)
 {
        struct bch_fs *c = trans->c;
        int ret;
 
-       if (likely(!(trans->flags & BTREE_INSERT_LAZY_RW)))
-               return -EROFS;
+       if (likely(!(flags & BTREE_INSERT_LAZY_RW)) ||
+           test_bit(BCH_FS_STARTED, &c->flags))
+               return -BCH_ERR_erofs_trans_commit;
 
        bch2_trans_unlock(trans);
 
-       ret = bch2_fs_read_write_early(c);
+       ret =   bch2_fs_read_write_early(c) ?:
+               bch2_trans_relock(trans);
        if (ret)
                return ret;
 
-       percpu_ref_get(&c->writes);
+       bch2_write_ref_get(c, BCH_WRITE_REF_trans);
        return 0;
 }
 
-static int extent_handle_overwrites(struct btree_trans *trans,
-                                   struct btree_insert_entry *i)
+/*
+ * This is for updates done in the early part of fsck - btree_gc - before we've
+ * gone RW. we only add the new key to the list of keys for journal replay to
+ * do.
+ */
+static noinline int
+do_bch2_trans_commit_to_journal_replay(struct btree_trans *trans)
 {
        struct bch_fs *c = trans->c;
-       struct btree_iter *iter, *update_iter;
-       struct bpos start = bkey_start_pos(&i->k->k);
-       struct bkey_i *update;
-       struct bkey_s_c k;
-       int ret = 0, compressed_sectors;
+       struct btree_insert_entry *i;
+       int ret = 0;
+
+       trans_for_each_update(trans, i) {
+               ret = bch2_journal_key_insert(c, i->btree_id, i->level, i->k);
+               if (ret)
+                       break;
+       }
+
+       return ret;
+}
+
+int __bch2_trans_commit(struct btree_trans *trans, unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_insert_entry *i = NULL;
+       struct btree_write_buffered_key *wb;
+       unsigned u64s;
+       int ret = 0;
+
+       if (!trans->nr_updates &&
+           !trans->nr_wb_updates &&
+           !trans->extra_journal_entries.nr)
+               goto out_reset;
+
+       if (flags & BTREE_INSERT_GC_LOCK_HELD)
+               lockdep_assert_held(&c->gc_lock);
+
+       ret = bch2_trans_commit_run_triggers(trans);
+       if (ret)
+               goto out_reset;
+
+       if (unlikely(!test_bit(BCH_FS_MAY_GO_RW, &c->flags))) {
+               ret = do_bch2_trans_commit_to_journal_replay(trans);
+               goto out_reset;
+       }
+
+       if (!(flags & BTREE_INSERT_NOCHECK_RW) &&
+           unlikely(!bch2_write_ref_tryget(c, BCH_WRITE_REF_trans))) {
+               ret = bch2_trans_commit_get_rw_cold(trans, flags);
+               if (ret)
+                       goto out_reset;
+       }
 
-       iter = bch2_trans_get_iter(trans, i->btree_id, start,
-                                  BTREE_ITER_INTENT|
-                                  BTREE_ITER_WITH_UPDATES|
-                                  BTREE_ITER_NOT_EXTENTS);
-       k = bch2_btree_iter_peek(iter);
-       if (!k.k || (ret = bkey_err(k)))
+       if (c->btree_write_buffer.state.nr > c->btree_write_buffer.size / 2 &&
+           mutex_trylock(&c->btree_write_buffer.flush_lock)) {
+               bch2_trans_begin(trans);
+               bch2_trans_unlock(trans);
+
+               ret = __bch2_btree_write_buffer_flush(trans,
+                                       flags|BTREE_INSERT_NOCHECK_RW, true);
+               if (!ret) {
+                       trace_and_count(c, trans_restart_write_buffer_flush, trans, _THIS_IP_);
+                       ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_write_buffer_flush);
+               }
                goto out;
+       }
+
+       EBUG_ON(test_bit(BCH_FS_CLEAN_SHUTDOWN, &c->flags));
+
+       memset(&trans->journal_preres, 0, sizeof(trans->journal_preres));
+
+       trans->journal_u64s             = trans->extra_journal_entries.nr;
+       trans->journal_preres_u64s      = 0;
 
-       if (bch2_bkey_maybe_mergable(k.k, &i->k->k)) {
-               update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
-               if ((ret = PTR_ERR_OR_ZERO(update)))
+       trans->journal_transaction_names = READ_ONCE(c->opts.journal_transaction_names);
+
+       if (trans->journal_transaction_names)
+               trans->journal_u64s += jset_u64s(JSET_ENTRY_LOG_U64s);
+
+       trans_for_each_update(trans, i) {
+               EBUG_ON(!i->path->should_be_locked);
+
+               ret = bch2_btree_path_upgrade(trans, i->path, i->level + 1);
+               if (unlikely(ret))
                        goto out;
 
-               bkey_reassemble(update, k);
+               EBUG_ON(!btree_node_intent_locked(i->path, i->level));
+
+               if (i->key_cache_already_flushed)
+                       continue;
+
+               /* we're going to journal the key being updated: */
+               u64s = jset_u64s(i->k->k.u64s);
+               if (i->cached &&
+                   likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY)))
+                       trans->journal_preres_u64s += u64s;
 
-               if (bch2_bkey_merge(c, bkey_i_to_s(update), bkey_i_to_s_c(i->k))) {
-                       update_iter = bch2_trans_copy_iter(trans, iter);
-                       ret = bch2_btree_delete_at(trans, update_iter, i->flags);
-                       bch2_trans_iter_put(trans, update_iter);
+               if (i->flags & BTREE_UPDATE_NOJOURNAL)
+                       continue;
 
-                       if (ret)
-                               goto out;
+               trans->journal_u64s += u64s;
+
+               /* and we're also going to log the overwrite: */
+               if (trans->journal_transaction_names)
+                       trans->journal_u64s += jset_u64s(i->old_k.u64s);
+       }
+
+       trans_for_each_wb_update(trans, wb)
+               trans->journal_u64s += jset_u64s(wb->k.k.u64s);
+
+       if (trans->extra_journal_res) {
+               ret = bch2_disk_reservation_add(c, trans->disk_res,
+                               trans->extra_journal_res,
+                               (flags & BTREE_INSERT_NOFAIL)
+                               ? BCH_DISK_RESERVATION_NOFAIL : 0);
+               if (ret)
+                       goto err;
+       }
+retry:
+       bch2_trans_verify_not_in_restart(trans);
+       memset(&trans->journal_res, 0, sizeof(trans->journal_res));
+
+       ret = do_bch2_trans_commit(trans, flags, &i, _RET_IP_);
+
+       /* make sure we didn't drop or screw up locks: */
+       bch2_trans_verify_locks(trans);
+
+       if (ret)
+               goto err;
+
+       trace_and_count(c, transaction_commit, trans, _RET_IP_);
+out:
+       bch2_journal_preres_put(&c->journal, &trans->journal_preres);
+
+       if (likely(!(flags & BTREE_INSERT_NOCHECK_RW)))
+               bch2_write_ref_put(c, BCH_WRITE_REF_trans);
+out_reset:
+       bch2_trans_reset_updates(trans);
 
-                       i->k = update;
-                       goto next;
+       return ret;
+err:
+       ret = bch2_trans_commit_error(trans, flags, i, ret, _RET_IP_);
+       if (ret)
+               goto out;
+
+       goto retry;
+}
+
+static noinline int __check_pos_snapshot_overwritten(struct btree_trans *trans,
+                                         enum btree_id id,
+                                         struct bpos pos)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret;
+
+       bch2_trans_iter_init(trans, &iter, id, pos,
+                            BTREE_ITER_NOT_EXTENTS|
+                            BTREE_ITER_ALL_SNAPSHOTS);
+       while (1) {
+               k = bch2_btree_iter_prev(&iter);
+               ret = bkey_err(k);
+               if (ret)
+                       break;
+
+               if (!k.k)
+                       break;
+
+               if (!bkey_eq(pos, k.k->p))
+                       break;
+
+               if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {
+                       ret = 1;
+                       break;
                }
        }
+       bch2_trans_iter_exit(trans, &iter);
+
+       return ret;
+}
+
+static inline int check_pos_snapshot_overwritten(struct btree_trans *trans,
+                                         enum btree_id id,
+                                         struct bpos pos)
+{
+       if (!btree_type_has_snapshots(id) ||
+           pos.snapshot == U32_MAX ||
+           !snapshot_t(trans->c, pos.snapshot)->children[0])
+               return 0;
+
+       return __check_pos_snapshot_overwritten(trans, id, pos);
+}
+
+static noinline int extent_front_merge(struct btree_trans *trans,
+                                      struct btree_iter *iter,
+                                      struct bkey_s_c k,
+                                      struct bkey_i **insert,
+                                      enum btree_update_flags flags)
+{
+       struct bch_fs *c = trans->c;
+       struct bkey_i *update;
+       int ret;
+
+       update = bch2_bkey_make_mut(trans, k);
+       ret = PTR_ERR_OR_ZERO(update);
+       if (ret)
+               return ret;
+
+       if (!bch2_bkey_merge(c, bkey_i_to_s(update), bkey_i_to_s_c(*insert)))
+               return 0;
+
+       ret =   check_pos_snapshot_overwritten(trans, iter->btree_id, k.k->p) ?:
+               check_pos_snapshot_overwritten(trans, iter->btree_id, (*insert)->k.p);
+       if (ret < 0)
+               return ret;
+       if (ret)
+               return 0;
+
+       ret = bch2_btree_delete_at(trans, iter, flags);
+       if (ret)
+               return ret;
+
+       *insert = update;
+       return 0;
+}
+
+static noinline int extent_back_merge(struct btree_trans *trans,
+                                     struct btree_iter *iter,
+                                     struct bkey_i *insert,
+                                     struct bkey_s_c k)
+{
+       struct bch_fs *c = trans->c;
+       int ret;
+
+       ret =   check_pos_snapshot_overwritten(trans, iter->btree_id, insert->k.p) ?:
+               check_pos_snapshot_overwritten(trans, iter->btree_id, k.k->p);
+       if (ret < 0)
+               return ret;
+       if (ret)
+               return 0;
+
+       bch2_bkey_merge(c, bkey_i_to_s(insert), k);
+       return 0;
+}
+
+/*
+ * When deleting, check if we need to emit a whiteout (because we're overwriting
+ * something in an ancestor snapshot)
+ */
+static int need_whiteout_for_snapshot(struct btree_trans *trans,
+                                     enum btree_id btree_id, struct bpos pos)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u32 snapshot = pos.snapshot;
+       int ret;
+
+       if (!bch2_snapshot_parent(trans->c, pos.snapshot))
+               return 0;
+
+       pos.snapshot++;
+
+       for_each_btree_key_norestart(trans, iter, btree_id, pos,
+                          BTREE_ITER_ALL_SNAPSHOTS|
+                          BTREE_ITER_NOPRESERVE, k, ret) {
+               if (!bkey_eq(k.k->p, pos))
+                       break;
+
+               if (bch2_snapshot_is_ancestor(trans->c, snapshot,
+                                             k.k->p.snapshot)) {
+                       ret = !bkey_whiteout(k.k);
+                       break;
+               }
+       }
+       bch2_trans_iter_exit(trans, &iter);
+
+       return ret;
+}
+int bch2_trans_update_extent(struct btree_trans *trans,
+                            struct btree_iter *orig_iter,
+                            struct bkey_i *insert,
+                            enum btree_update_flags flags)
+{
+       struct btree_iter iter;
+       struct bpos start = bkey_start_pos(&insert->k);
+       struct bkey_i *update;
+       struct bkey_s_c k;
+       enum btree_id btree_id = orig_iter->btree_id;
+       int ret = 0, compressed_sectors;
+
+       bch2_trans_iter_init(trans, &iter, btree_id, start,
+                            BTREE_ITER_INTENT|
+                            BTREE_ITER_WITH_UPDATES|
+                            BTREE_ITER_NOT_EXTENTS);
+       k = bch2_btree_iter_peek_upto(&iter, POS(insert->k.p.inode, U64_MAX));
+       if ((ret = bkey_err(k)))
+               goto err;
+       if (!k.k)
+               goto out;
+
+       if (bkey_eq(k.k->p, bkey_start_pos(&insert->k))) {
+               if (bch2_bkey_maybe_mergable(k.k, &insert->k)) {
+                       ret = extent_front_merge(trans, &iter, k, &insert, flags);
+                       if (ret)
+                               goto err;
+               }
 
-       if (!bkey_cmp(k.k->p, bkey_start_pos(&i->k->k)))
                goto next;
+       }
+
+       while (bkey_gt(insert->k.p, bkey_start_pos(k.k))) {
+               bool front_split = bkey_lt(bkey_start_pos(k.k), start);
+               bool back_split  = bkey_gt(k.k->p, insert->k.p);
 
-       while (bkey_cmp(i->k->k.p, bkey_start_pos(k.k)) > 0) {
                /*
                 * If we're going to be splitting a compressed extent, note it
                 * so that __bch2_trans_commit() can increase our disk
                 * reservation:
                 */
-               if (bkey_cmp(bkey_start_pos(k.k), start) < 0 &&
-                   bkey_cmp(k.k->p, i->k->k.p) > 0 &&
+               if (((front_split && back_split) ||
+                    ((front_split || back_split) && k.k->p.snapshot != insert->k.p.snapshot)) &&
                    (compressed_sectors = bch2_bkey_sectors_compressed(k)))
                        trans->extra_journal_res += compressed_sectors;
 
-               if (bkey_cmp(bkey_start_pos(k.k), start) < 0) {
-                       update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+               if (front_split) {
+                       update = bch2_bkey_make_mut(trans, k);
                        if ((ret = PTR_ERR_OR_ZERO(update)))
-                               goto out;
-
-                       bkey_reassemble(update, k);
+                               goto err;
 
                        bch2_cut_back(start, update);
 
-                       update_iter = bch2_trans_get_iter(trans, i->btree_id, update->k.p,
-                                                         BTREE_ITER_NOT_EXTENTS|
-                                                         BTREE_ITER_INTENT);
-                       ret = bch2_btree_iter_traverse(update_iter);
-                       if (ret) {
-                               bch2_trans_iter_put(trans, update_iter);
-                               goto out;
-                       }
+                       ret = bch2_btree_insert_nonextent(trans, btree_id, update,
+                                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
+                       if (ret)
+                               goto err;
+               }
+
+               if (k.k->p.snapshot != insert->k.p.snapshot &&
+                   (front_split || back_split)) {
+                       update = bch2_bkey_make_mut(trans, k);
+                       if ((ret = PTR_ERR_OR_ZERO(update)))
+                               goto err;
+
+                       bch2_cut_front(start, update);
+                       bch2_cut_back(insert->k.p, update);
 
-                       bch2_trans_update(trans, update_iter, update,
-                                         BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
-                                         i->flags);
-                       bch2_trans_iter_put(trans, update_iter);
+                       ret = bch2_btree_insert_nonextent(trans, btree_id, update,
+                                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
+                       if (ret)
+                               goto err;
                }
 
-               if (bkey_cmp(k.k->p, i->k->k.p) <= 0) {
-                       update_iter = bch2_trans_copy_iter(trans, iter);
-                       ret = bch2_btree_delete_at(trans, update_iter,
-                                                  i->flags);
-                       bch2_trans_iter_put(trans, update_iter);
+               if (bkey_le(k.k->p, insert->k.p)) {
+                       update = bch2_trans_kmalloc(trans, sizeof(*update));
+                       if ((ret = PTR_ERR_OR_ZERO(update)))
+                               goto err;
+
+                       bkey_init(&update->k);
+                       update->k.p = k.k->p;
+                       update->k.p.snapshot = insert->k.p.snapshot;
 
+                       if (insert->k.p.snapshot != k.k->p.snapshot ||
+                           (btree_type_has_snapshots(btree_id) &&
+                            need_whiteout_for_snapshot(trans, btree_id, update->k.p)))
+                               update->k.type = KEY_TYPE_whiteout;
+
+                       ret = bch2_btree_insert_nonextent(trans, btree_id, update,
+                                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
                        if (ret)
-                               goto out;
+                               goto err;
                }
 
-               if (bkey_cmp(k.k->p, i->k->k.p) > 0) {
-                       update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+               if (back_split) {
+                       update = bch2_bkey_make_mut(trans, k);
                        if ((ret = PTR_ERR_OR_ZERO(update)))
-                               goto out;
+                               goto err;
 
-                       bkey_reassemble(update, k);
-                       bch2_cut_front(i->k->k.p, update);
+                       bch2_cut_front(insert->k.p, update);
 
-                       bch2_trans_update(trans, iter, update, i->flags);
+                       ret = bch2_trans_update_by_path(trans, iter.path, update,
+                                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+                                                 flags);
+                       if (ret)
+                               goto err;
                        goto out;
                }
 next:
-               k = bch2_btree_iter_next(iter);
-               if (!k.k || (ret = bkey_err(k)))
+               bch2_btree_iter_advance(&iter);
+               k = bch2_btree_iter_peek_upto(&iter, POS(insert->k.p.inode, U64_MAX));
+               if ((ret = bkey_err(k)))
+                       goto err;
+               if (!k.k)
                        goto out;
        }
 
-       bch2_bkey_merge(c, bkey_i_to_s(i->k), k);
+       if (bch2_bkey_maybe_mergable(&insert->k, k.k)) {
+               ret = extent_back_merge(trans, &iter, insert, k);
+               if (ret)
+                       goto err;
+       }
 out:
-       bch2_trans_iter_put(trans, iter);
+       if (!bkey_deleted(&insert->k)) {
+               /*
+                * Rewinding iterators is expensive: get a new one and the one
+                * that points to the start of insert will be cloned from:
+                */
+               bch2_trans_iter_exit(trans, &iter);
+               bch2_trans_iter_init(trans, &iter, btree_id, insert->k.p,
+                                    BTREE_ITER_NOT_EXTENTS|
+                                    BTREE_ITER_INTENT);
+               ret   = bch2_btree_iter_traverse(&iter) ?:
+                       bch2_trans_update(trans, &iter, insert, flags);
+       }
+err:
+       bch2_trans_iter_exit(trans, &iter);
 
        return ret;
 }
 
-int __bch2_trans_commit(struct btree_trans *trans)
+static int __must_check
+bch2_trans_update_by_path_trace(struct btree_trans *trans, struct btree_path *path,
+                               struct bkey_i *k, enum btree_update_flags flags,
+                               unsigned long ip);
+
+static noinline int flush_new_cached_update(struct btree_trans *trans,
+                                           struct btree_path *path,
+                                           struct btree_insert_entry *i,
+                                           enum btree_update_flags flags,
+                                           unsigned long ip)
 {
-       struct btree_insert_entry *i = NULL;
-       struct btree_iter *iter;
-       bool trans_trigger_run;
-       unsigned u64s;
-       int ret = 0;
+       struct btree_path *btree_path;
+       int ret;
 
-       if (!trans->nr_updates &&
-           !trans->extra_journal_entry_u64s)
-               goto out_reset;
+       i->key_cache_already_flushed = true;
+       i->flags |= BTREE_TRIGGER_NORUN;
 
-       if (trans->flags & BTREE_INSERT_GC_LOCK_HELD)
-               lockdep_assert_held(&trans->c->gc_lock);
+       btree_path = bch2_path_get(trans, path->btree_id, path->pos, 1, 0,
+                                  BTREE_ITER_INTENT, _THIS_IP_);
 
-       memset(&trans->journal_preres, 0, sizeof(trans->journal_preres));
+       ret = bch2_btree_path_traverse(trans, btree_path, 0);
+       if (ret)
+               goto err;
 
-       trans->journal_u64s             = trans->extra_journal_entry_u64s;
-       trans->journal_preres_u64s      = 0;
+       btree_path_set_should_be_locked(btree_path);
+       ret = bch2_trans_update_by_path_trace(trans, btree_path, i->k, flags, ip);
+err:
+       bch2_path_put(trans, btree_path, true);
+       return ret;
+}
 
-       if (!(trans->flags & BTREE_INSERT_NOCHECK_RW) &&
-           unlikely(!percpu_ref_tryget(&trans->c->writes))) {
-               ret = bch2_trans_commit_get_rw_cold(trans);
-               if (ret)
-                       goto out_reset;
-       }
+static int __must_check
+bch2_trans_update_by_path_trace(struct btree_trans *trans, struct btree_path *path,
+                               struct bkey_i *k, enum btree_update_flags flags,
+                               unsigned long ip)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_insert_entry *i, n;
+       int cmp;
+
+       EBUG_ON(!path->should_be_locked);
+       EBUG_ON(trans->nr_updates >= BTREE_ITER_MAX);
+       EBUG_ON(!bpos_eq(k->k.p, path->pos));
+
+       n = (struct btree_insert_entry) {
+               .flags          = flags,
+               .bkey_type      = __btree_node_type(path->level, path->btree_id),
+               .btree_id       = path->btree_id,
+               .level          = path->level,
+               .cached         = path->cached,
+               .path           = path,
+               .k              = k,
+               .ip_allocated   = ip,
+       };
 
 #ifdef CONFIG_BCACHEFS_DEBUG
        trans_for_each_update(trans, i)
-               if (btree_iter_type(i->iter) != BTREE_ITER_CACHED &&
-                   !(i->flags & BTREE_TRIGGER_NORUN))
-                       bch2_btree_key_cache_verify_clean(trans,
-                                       i->btree_id, i->k->k.p);
+               BUG_ON(i != trans->updates &&
+                      btree_insert_entry_cmp(i - 1, i) >= 0);
 #endif
 
        /*
-        * Running triggers will append more updates to the list of updates as
-        * we're walking it:
+        * Pending updates are kept sorted: first, find position of new update,
+        * then delete/trim any updates the new update overwrites:
         */
-       do {
-               trans_trigger_run = false;
+       trans_for_each_update(trans, i) {
+               cmp = btree_insert_entry_cmp(&n, i);
+               if (cmp <= 0)
+                       break;
+       }
 
-               trans_for_each_update(trans, i) {
-                       if ((BTREE_NODE_TYPE_HAS_TRANS_TRIGGERS & (1U << i->bkey_type)) &&
-                           !i->trans_triggers_run) {
-                               i->trans_triggers_run = true;
-                               trans_trigger_run = true;
-
-                               ret = bch2_trans_mark_update(trans, i->iter,
-                                                            i->k, i->flags);
-                               if (unlikely(ret)) {
-                                       if (ret == -EINTR)
-                                               trace_trans_restart_mark(trans->ip, _RET_IP_,
-                                                                        i->iter->btree_id,
-                                                                        &i->iter->pos);
-                                       goto out;
-                               }
+       if (!cmp && i < trans->updates + trans->nr_updates) {
+               EBUG_ON(i->insert_trigger_run || i->overwrite_trigger_run);
+
+               bch2_path_put(trans, i->path, true);
+               i->flags        = n.flags;
+               i->cached       = n.cached;
+               i->k            = n.k;
+               i->path         = n.path;
+               i->ip_allocated = n.ip_allocated;
+       } else {
+               array_insert_item(trans->updates, trans->nr_updates,
+                                 i - trans->updates, n);
+
+               i->old_v = bch2_btree_path_peek_slot_exact(path, &i->old_k).v;
+               i->old_btree_u64s = !bkey_deleted(&i->old_k) ? i->old_k.u64s : 0;
+
+               if (unlikely(trans->journal_replay_not_finished)) {
+                       struct bkey_i *j_k =
+                               bch2_journal_keys_peek_slot(c, n.btree_id, n.level, k->k.p);
+
+                       if (j_k) {
+                               i->old_k = j_k->k;
+                               i->old_v = &j_k->v;
                        }
                }
-       } while (trans_trigger_run);
+       }
 
-       trans_for_each_update(trans, i) {
-               BUG_ON(!i->iter->should_be_locked);
-
-               if (unlikely(!bch2_btree_iter_upgrade(i->iter, i->level + 1))) {
-                       trace_trans_restart_upgrade(trans->ip, _RET_IP_,
-                                                   i->iter->btree_id,
-                                                   &i->iter->pos);
-                       trans->restarted = true;
-                       ret = -EINTR;
-                       goto out;
-               }
+       __btree_path_get(i->path, true);
 
-               BUG_ON(!btree_node_intent_locked(i->iter, i->level));
+       /*
+        * If a key is present in the key cache, it must also exist in the
+        * btree - this is necessary for cache coherency. When iterating over
+        * a btree that's cached in the key cache, the btree iter code checks
+        * the key cache - but the key has to exist in the btree for that to
+        * work:
+        */
+       if (path->cached &&
+           bkey_deleted(&i->old_k) &&
+           !(flags & BTREE_UPDATE_NO_KEY_CACHE_COHERENCY))
+               return flush_new_cached_update(trans, path, i, flags, ip);
 
-               u64s = jset_u64s(i->k->k.u64s);
-               if (btree_iter_type(i->iter) == BTREE_ITER_CACHED &&
-                   likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY)))
-                       trans->journal_preres_u64s += u64s;
-               trans->journal_u64s += u64s;
-       }
+       return 0;
+}
+
+static inline int __must_check
+bch2_trans_update_by_path(struct btree_trans *trans, struct btree_path *path,
+                         struct bkey_i *k, enum btree_update_flags flags)
+{
+       return bch2_trans_update_by_path_trace(trans, path, k, flags, _RET_IP_);
+}
+
+int __must_check bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
+                                  struct bkey_i *k, enum btree_update_flags flags)
+{
+       struct btree_path *path = iter->update_path ?: iter->path;
+       struct bkey_cached *ck;
+       int ret;
+
+       if (iter->flags & BTREE_ITER_IS_EXTENTS)
+               return bch2_trans_update_extent(trans, iter, k, flags);
+
+       if (bkey_deleted(&k->k) &&
+           !(flags & BTREE_UPDATE_KEY_CACHE_RECLAIM) &&
+           (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)) {
+               ret = need_whiteout_for_snapshot(trans, iter->btree_id, k->k.p);
+               if (unlikely(ret < 0))
+                       return ret;
 
-       if (trans->extra_journal_res) {
-               ret = bch2_disk_reservation_add(trans->c, trans->disk_res,
-                               trans->extra_journal_res,
-                               (trans->flags & BTREE_INSERT_NOFAIL)
-                               ? BCH_DISK_RESERVATION_NOFAIL : 0);
                if (ret)
-                       goto err;
+                       k->k.type = KEY_TYPE_whiteout;
        }
-retry:
-       BUG_ON(trans->restarted);
-       memset(&trans->journal_res, 0, sizeof(trans->journal_res));
 
-       ret = do_bch2_trans_commit(trans, &i, _RET_IP_);
+       /*
+        * Ensure that updates to cached btrees go to the key cache:
+        */
+       if (!(flags & BTREE_UPDATE_KEY_CACHE_RECLAIM) &&
+           !path->cached &&
+           !path->level &&
+           btree_id_cached(trans->c, path->btree_id)) {
+               if (!iter->key_cache_path ||
+                   !iter->key_cache_path->should_be_locked ||
+                   !bpos_eq(iter->key_cache_path->pos, k->k.p)) {
+                       if (!iter->key_cache_path)
+                               iter->key_cache_path =
+                                       bch2_path_get(trans, path->btree_id, path->pos, 1, 0,
+                                                     BTREE_ITER_INTENT|
+                                                     BTREE_ITER_CACHED, _THIS_IP_);
+
+                       iter->key_cache_path =
+                               bch2_btree_path_set_pos(trans, iter->key_cache_path, path->pos,
+                                                       iter->flags & BTREE_ITER_INTENT,
+                                                       _THIS_IP_);
+
+                       ret = bch2_btree_path_traverse(trans, iter->key_cache_path,
+                                                      BTREE_ITER_CACHED);
+                       if (unlikely(ret))
+                               return ret;
 
-       /* make sure we didn't drop or screw up locks: */
-       bch2_btree_trans_verify_locks(trans);
+                       ck = (void *) iter->key_cache_path->l[0].b;
 
-       if (ret)
-               goto err;
+                       if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
+                               trace_and_count(trans->c, trans_restart_key_cache_raced, trans, _RET_IP_);
+                               return btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_raced);
+                       }
 
-       trans_for_each_iter(trans, iter)
-               if (btree_iter_live(trans, iter) &&
-                   (iter->flags & BTREE_ITER_SET_POS_AFTER_COMMIT))
-                       bch2_btree_iter_set_pos(iter, iter->pos_after_commit);
-out:
-       bch2_journal_preres_put(&trans->c->journal, &trans->journal_preres);
+                       btree_path_set_should_be_locked(iter->key_cache_path);
+               }
 
-       if (likely(!(trans->flags & BTREE_INSERT_NOCHECK_RW)))
-               percpu_ref_put(&trans->c->writes);
-out_reset:
-       trans->extra_journal_res        = 0;
-       trans->nr_updates               = 0;
-       trans->hooks                    = NULL;
-       trans->extra_journal_entries    = NULL;
-       trans->extra_journal_entry_u64s = 0;
-
-       if (trans->fs_usage_deltas) {
-               trans->fs_usage_deltas->used = 0;
-               memset(&trans->fs_usage_deltas->memset_start, 0,
-                      (void *) &trans->fs_usage_deltas->memset_end -
-                      (void *) &trans->fs_usage_deltas->memset_start);
+               path = iter->key_cache_path;
        }
 
-       return ret;
-err:
-       ret = bch2_trans_commit_error(trans, i, ret, _RET_IP_);
-       if (ret)
-               goto out;
-
-       goto retry;
+       return bch2_trans_update_by_path(trans, path, k, flags);
 }
 
-int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
-                     struct bkey_i *k, enum btree_update_flags flags)
+int __must_check bch2_trans_update_buffered(struct btree_trans *trans,
+                                           enum btree_id btree,
+                                           struct bkey_i *k)
 {
-       struct btree_insert_entry *i, n = (struct btree_insert_entry) {
-               .flags          = flags,
-               .bkey_type      = __btree_node_type(iter->level, iter->btree_id),
-               .btree_id       = iter->btree_id,
-               .level          = iter->level,
-               .iter           = iter,
-               .k              = k
-       };
-       bool is_extent = (iter->flags & BTREE_ITER_IS_EXTENTS) != 0;
-       int ret = 0;
+       struct btree_write_buffered_key *i;
+       int ret;
 
-       BUG_ON(trans->nr_updates >= BTREE_ITER_MAX);
-       BUG_ON(!iter->should_be_locked);
+       EBUG_ON(trans->nr_wb_updates > trans->wb_updates_size);
+       EBUG_ON(k->k.u64s > BTREE_WRITE_BUFERED_U64s_MAX);
 
-#ifdef CONFIG_BCACHEFS_DEBUG
-       trans_for_each_update(trans, i)
-               BUG_ON(i != trans->updates &&
-                      btree_insert_entry_cmp(i - 1, i) >= 0);
-#endif
-
-       if (is_extent) {
-               ret = extent_handle_overwrites(trans, &n);
-               if (ret)
-                       return ret;
+       trans_for_each_wb_update(trans, i) {
+               if (i->btree == btree && bpos_eq(i->k.k.p, k->k.p)) {
+                       bkey_copy(&i->k, k);
+                       return 0;
+               }
+       }
 
-               iter->pos_after_commit = k->k.p;
-               iter->flags |= BTREE_ITER_SET_POS_AFTER_COMMIT;
+       if (!trans->wb_updates ||
+           trans->nr_wb_updates == trans->wb_updates_size) {
+               struct btree_write_buffered_key *u;
 
-               if (bkey_deleted(&n.k->k))
-                       return 0;
+               if (trans->nr_wb_updates == trans->wb_updates_size) {
+                       struct btree_transaction_stats *s = btree_trans_stats(trans);
 
-               n.iter = bch2_trans_get_iter(trans, n.btree_id, n.k->k.p,
-                                            BTREE_ITER_INTENT|
-                                            BTREE_ITER_NOT_EXTENTS);
-               ret = bch2_btree_iter_traverse(n.iter);
-               bch2_trans_iter_put(trans, n.iter);
+                       BUG_ON(trans->wb_updates_size > U8_MAX / 2);
+                       trans->wb_updates_size = max(1, trans->wb_updates_size * 2);
+                       if (s)
+                               s->wb_updates_size = trans->wb_updates_size;
+               }
 
+               u = bch2_trans_kmalloc_nomemzero(trans,
+                                       trans->wb_updates_size *
+                                       sizeof(struct btree_write_buffered_key));
+               ret = PTR_ERR_OR_ZERO(u);
                if (ret)
                        return ret;
-       }
 
-       BUG_ON(n.iter->flags & BTREE_ITER_IS_EXTENTS);
-
-       n.iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
-
-       /*
-        * Pending updates are kept sorted: first, find position of new update,
-        * then delete/trim any updates the new update overwrites:
-        */
-       trans_for_each_update(trans, i)
-               if (btree_insert_entry_cmp(&n, i) <= 0)
-                       break;
+               if (trans->nr_wb_updates)
+                       memcpy(u, trans->wb_updates, trans->nr_wb_updates *
+                              sizeof(struct btree_write_buffered_key));
+               trans->wb_updates = u;
+       }
 
-       if (i < trans->updates + trans->nr_updates &&
-           !btree_insert_entry_cmp(&n, i)) {
-               BUG_ON(i->trans_triggers_run);
+       trans->wb_updates[trans->nr_wb_updates] = (struct btree_write_buffered_key) {
+               .btree  = btree,
+       };
 
-               /*
-                * This is a hack to ensure that inode creates update the btree,
-                * not the key cache, which helps with cache coherency issues in
-                * other areas:
-                */
-               if (btree_iter_type(n.iter) == BTREE_ITER_CACHED &&
-                   btree_iter_type(i->iter) != BTREE_ITER_CACHED) {
-                       i->k = n.k;
-                       i->flags = n.flags;
-               } else {
-                       *i = n;
-               }
-       } else
-               array_insert_item(trans->updates, trans->nr_updates,
-                                 i - trans->updates, n);
+       bkey_copy(&trans->wb_updates[trans->nr_wb_updates].k, k);
+       trans->nr_wb_updates++;
 
        return 0;
 }
@@ -1068,18 +1729,34 @@ void bch2_trans_commit_hook(struct btree_trans *trans,
        trans->hooks = h;
 }
 
-int __bch2_btree_insert(struct btree_trans *trans,
-                       enum btree_id id, struct bkey_i *k)
+int bch2_btree_insert_nonextent(struct btree_trans *trans,
+                               enum btree_id btree, struct bkey_i *k,
+                               enum btree_update_flags flags)
 {
-       struct btree_iter *iter;
+       struct btree_iter iter;
        int ret;
 
-       iter = bch2_trans_get_iter(trans, id, bkey_start_pos(&k->k),
-                                  BTREE_ITER_INTENT);
+       bch2_trans_iter_init(trans, &iter, btree, k->k.p,
+                            BTREE_ITER_NOT_EXTENTS|
+                            BTREE_ITER_INTENT);
+       ret   = bch2_btree_iter_traverse(&iter) ?:
+               bch2_trans_update(trans, &iter, k, flags);
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+int __bch2_btree_insert(struct btree_trans *trans, enum btree_id id,
+                       struct bkey_i *k, enum btree_update_flags flags)
+{
+       struct btree_iter iter;
+       int ret;
 
-       ret   = bch2_btree_iter_traverse(iter) ?:
-               bch2_trans_update(trans, iter, k, 0);
-       bch2_trans_iter_put(trans, iter);
+       bch2_trans_iter_init(trans, &iter, id, bkey_start_pos(&k->k),
+                            BTREE_ITER_CACHED|
+                            BTREE_ITER_INTENT);
+       ret   = bch2_btree_iter_traverse(&iter) ?:
+               bch2_trans_update(trans, &iter, k, flags);
+       bch2_trans_iter_exit(trans, &iter);
        return ret;
 }
 
@@ -1096,11 +1773,11 @@ int bch2_btree_insert(struct bch_fs *c, enum btree_id id,
                      u64 *journal_seq, int flags)
 {
        return bch2_trans_do(c, disk_res, journal_seq, flags,
-                            __bch2_btree_insert(&trans, id, k));
+                            __bch2_btree_insert(&trans, id, k, 0));
 }
 
-int bch2_btree_delete_at(struct btree_trans *trans,
-                        struct btree_iter *iter, unsigned update_flags)
+int bch2_btree_delete_extent_at(struct btree_trans *trans, struct btree_iter *iter,
+                               unsigned len, unsigned update_flags)
 {
        struct bkey_i *k;
 
@@ -1110,25 +1787,36 @@ int bch2_btree_delete_at(struct btree_trans *trans,
 
        bkey_init(&k->k);
        k->k.p = iter->pos;
+       bch2_key_resize(&k->k, len);
        return bch2_trans_update(trans, iter, k, update_flags);
 }
 
+int bch2_btree_delete_at(struct btree_trans *trans,
+                        struct btree_iter *iter, unsigned update_flags)
+{
+       return bch2_btree_delete_extent_at(trans, iter, 0, update_flags);
+}
+
 int bch2_btree_delete_range_trans(struct btree_trans *trans, enum btree_id id,
                                  struct bpos start, struct bpos end,
+                                 unsigned update_flags,
                                  u64 *journal_seq)
 {
-       struct btree_iter *iter;
+       u32 restart_count = trans->restart_count;
+       struct btree_iter iter;
        struct bkey_s_c k;
        int ret = 0;
 
-       iter = bch2_trans_get_iter(trans, id, start, BTREE_ITER_INTENT);
-retry:
-       while ((bch2_trans_begin(trans),
-              (k = bch2_btree_iter_peek(iter)).k) &&
-              !(ret = bkey_err(k)) &&
-              bkey_cmp(iter->pos, end) < 0) {
+       bch2_trans_iter_init(trans, &iter, id, start, BTREE_ITER_INTENT);
+       while ((k = bch2_btree_iter_peek_upto(&iter, end)).k) {
+               struct disk_reservation disk_res =
+                       bch2_disk_reservation_init(trans->c, 0);
                struct bkey_i delete;
 
+               ret = bkey_err(k);
+               if (ret)
+                       goto err;
+
                bkey_init(&delete.k);
 
                /*
@@ -1145,36 +1833,35 @@ retry:
                 * (bch2_btree_iter_peek() does guarantee that iter.pos >=
                 * bkey_start_pos(k.k)).
                 */
-               delete.k.p = iter->pos;
+               delete.k.p = iter.pos;
 
-               if (btree_node_type_is_extents(iter->btree_id)) {
-                       unsigned max_sectors =
-                               KEY_SIZE_MAX & (~0 << trans->c->block_bits);
+               if (iter.flags & BTREE_ITER_IS_EXTENTS)
+                       bch2_key_resize(&delete.k,
+                                       bpos_min(end, k.k->p).offset -
+                                       iter.pos.offset);
 
-                       /* create the biggest key we can */
-                       bch2_key_resize(&delete.k, max_sectors);
-                       bch2_cut_back(end, &delete);
-
-                       ret = bch2_extent_trim_atomic(&delete, iter);
-                       if (ret)
-                               break;
-               }
+               ret   = bch2_trans_update(trans, &iter, &delete, update_flags) ?:
+                       bch2_trans_commit(trans, &disk_res, journal_seq,
+                                         BTREE_INSERT_NOFAIL);
+               bch2_disk_reservation_put(trans->c, &disk_res);
+err:
+               /*
+                * the bch2_trans_begin() call is in a weird place because we
+                * need to call it after every transaction commit, to avoid path
+                * overflow, but don't want to call it if the delete operation
+                * is a no-op and we have no work to do:
+                */
+               bch2_trans_begin(trans);
 
-               ret   = bch2_trans_update(trans, iter, &delete, 0) ?:
-                       bch2_trans_commit(trans, NULL, journal_seq,
-                                       BTREE_INSERT_NOFAIL);
+               if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+                       ret = 0;
                if (ret)
                        break;
-
-               bch2_trans_cond_resched(trans);
        }
+       bch2_trans_iter_exit(trans, &iter);
 
-       if (ret == -EINTR) {
-               ret = 0;
-               goto retry;
-       }
-
-       bch2_trans_iter_free(trans, iter);
+       if (!ret && trans_was_restarted(trans, restart_count))
+               ret = -BCH_ERR_transaction_restart_nested;
        return ret;
 }
 
@@ -1185,8 +1872,81 @@ retry:
  */
 int bch2_btree_delete_range(struct bch_fs *c, enum btree_id id,
                            struct bpos start, struct bpos end,
+                           unsigned update_flags,
                            u64 *journal_seq)
 {
-       return bch2_trans_do(c, NULL, journal_seq, 0,
-                            bch2_btree_delete_range_trans(&trans, id, start, end, journal_seq));
+       int ret = bch2_trans_run(c,
+                       bch2_btree_delete_range_trans(&trans, id, start, end,
+                                                     update_flags, journal_seq));
+       if (ret == -BCH_ERR_transaction_restart_nested)
+               ret = 0;
+       return ret;
+}
+
+static int __bch2_trans_log_msg(darray_u64 *entries, const char *fmt, va_list args)
+{
+       struct printbuf buf = PRINTBUF;
+       struct jset_entry_log *l;
+       unsigned u64s;
+       int ret;
+
+       prt_vprintf(&buf, fmt, args);
+       ret = buf.allocation_failure ? -ENOMEM : 0;
+       if (ret)
+               goto err;
+
+       u64s = DIV_ROUND_UP(buf.pos, sizeof(u64));
+
+       ret = darray_make_room(entries, jset_u64s(u64s));
+       if (ret)
+               goto err;
+
+       l = (void *) &darray_top(*entries);
+       l->entry.u64s           = cpu_to_le16(u64s);
+       l->entry.btree_id       = 0;
+       l->entry.level          = 1;
+       l->entry.type           = BCH_JSET_ENTRY_log;
+       l->entry.pad[0]         = 0;
+       l->entry.pad[1]         = 0;
+       l->entry.pad[2]         = 0;
+       memcpy(l->d, buf.buf, buf.pos);
+       while (buf.pos & 7)
+               l->d[buf.pos++] = '\0';
+
+       entries->nr += jset_u64s(u64s);
+err:
+       printbuf_exit(&buf);
+       return ret;
+}
+
+int bch2_trans_log_msg(struct btree_trans *trans, const char *fmt, ...)
+{
+       va_list args;
+       int ret;
+
+       va_start(args, fmt);
+       ret = __bch2_trans_log_msg(&trans->extra_journal_entries, fmt, args);
+       va_end(args);
+
+       return ret;
+}
+
+int bch2_fs_log_msg(struct bch_fs *c, const char *fmt, ...)
+{
+       va_list args;
+       int ret;
+
+       va_start(args, fmt);
+
+       if (!test_bit(JOURNAL_STARTED, &c->journal.flags)) {
+               ret = __bch2_trans_log_msg(&c->journal.early_journal_entries, fmt, args);
+       } else {
+               ret = bch2_trans_do(c, NULL, NULL, BTREE_INSERT_LAZY_RW,
+                       __bch2_trans_log_msg(&trans.extra_journal_entries, fmt, args));
+       }
+
+       va_end(args);
+
+       return ret;
+
 }