bcachefs: Split up btree_update_leaf.c

We now have
  btree_trans_commit.c
  btree_update.c

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

5 files changed, 964 insertions, 954 deletions

diff --git a/fs/bcachefs/Makefile b/fs/bcachefs/Makefile
index 13cacf2d8bfb..1bb4d159630b 100644
--- a/fs/bcachefs/Makefile
+++ b/fs/bcachefs/Makefile
@@ -15,8 +15,9 @@ bcachefs-y		:=	\
 	btree_iter.o		\
 	btree_key_cache.o	\
 	btree_locking.o		\
+	btree_trans_commit.o	\
+	btree_update.o		\
 	btree_update_interior.o	\
-	btree_update_leaf.o	\
 	btree_write_buffer.o	\
 	buckets.o		\
 	buckets_waiting_for_journal.o	\
diff --git a/fs/bcachefs/btree_gc.h b/fs/bcachefs/btree_gc.h
index b45e382f7055..607575f83a00 100644
--- a/fs/bcachefs/btree_gc.h
+++ b/fs/bcachefs/btree_gc.h
@@ -2,6 +2,7 @@
 #ifndef _BCACHEFS_BTREE_GC_H
 #define _BCACHEFS_BTREE_GC_H
 
+#include "bkey.h"
 #include "btree_types.h"
 
 int bch2_check_topology(struct bch_fs *);
diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index 13e92452270e..4469b2e166eb 100644
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -221,6 +221,22 @@ struct btree_path *bch2_path_get(struct btree_trans *, enum btree_id, struct bpo
 				 unsigned, unsigned, unsigned, unsigned long);
 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *, struct bkey *);
 
+/*
+ * bch2_btree_path_peek_slot() for a cached iterator might return a key in a
+ * different snapshot:
+ */
+static inline 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 };
+}
+
 struct bkey_i *bch2_btree_journal_peek_slot(struct btree_trans *,
 					struct btree_iter *, struct bpos);
 
diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_trans_commit.c
index 369e37a415f3..2fa123ff953e 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_trans_commit.c
@@ -1,45 +1,22 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include "bcachefs.h"
-#include "btree_update.h"
-#include "btree_update_interior.h"
 #include "btree_gc.h"
 #include "btree_io.h"
 #include "btree_iter.h"
 #include "btree_key_cache.h"
-#include "btree_locking.h"
+#include "btree_update_interior.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 "trace.h"
+#include "subvolume.h"
 
 #include <linux/prefetch.h>
-#include <linux/sort.h>
-
-/*
- * bch2_btree_path_peek_slot() for a cached iterator might return a key in a
- * different snapshot:
- */
-static 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)
 {
@@ -64,20 +41,6 @@ static void verify_update_old_key(struct btree_trans *trans, struct btree_insert
 #endif
 }
 
-static int __must_check
-bch2_trans_update_by_path(struct btree_trans *, struct btree_path *,
-			  struct bkey_i *, enum btree_update_flags,
-			  unsigned long ip);
-
-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;
@@ -1191,917 +1154,3 @@ err:
 
 	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) ||
-	    bch2_snapshot_is_leaf(trans->c, pos.snapshot))
-		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_noupdate(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_insert_snapshot_whiteouts(struct btree_trans *trans,
-				   enum btree_id id,
-				   struct bpos old_pos,
-				   struct bpos new_pos)
-{
-	struct bch_fs *c = trans->c;
-	struct btree_iter old_iter, new_iter = { NULL };
-	struct bkey_s_c old_k, new_k;
-	snapshot_id_list s;
-	struct bkey_i *update;
-	int ret;
-
-	if (!bch2_snapshot_has_children(c, old_pos.snapshot))
-		return 0;
-
-	darray_init(&s);
-
-	bch2_trans_iter_init(trans, &old_iter, id, old_pos,
-			     BTREE_ITER_NOT_EXTENTS|
-			     BTREE_ITER_ALL_SNAPSHOTS);
-	while ((old_k = bch2_btree_iter_prev(&old_iter)).k &&
-	       !(ret = bkey_err(old_k)) &&
-	       bkey_eq(old_pos, old_k.k->p)) {
-		struct bpos whiteout_pos =
-			SPOS(new_pos.inode, new_pos.offset, old_k.k->p.snapshot);;
-
-		if (!bch2_snapshot_is_ancestor(c, old_k.k->p.snapshot, old_pos.snapshot) ||
-		    snapshot_list_has_ancestor(c, &s, old_k.k->p.snapshot))
-			continue;
-
-		new_k = bch2_bkey_get_iter(trans, &new_iter, id, whiteout_pos,
-					   BTREE_ITER_NOT_EXTENTS|
-					   BTREE_ITER_INTENT);
-		ret = bkey_err(new_k);
-		if (ret)
-			break;
-
-		if (new_k.k->type == KEY_TYPE_deleted) {
-			update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
-			ret = PTR_ERR_OR_ZERO(update);
-			if (ret)
-				break;
-
-			bkey_init(&update->k);
-			update->k.p		= whiteout_pos;
-			update->k.type		= KEY_TYPE_whiteout;
-
-			ret = bch2_trans_update(trans, &new_iter, update,
-						BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-		}
-		bch2_trans_iter_exit(trans, &new_iter);
-
-		ret = snapshot_list_add(c, &s, old_k.k->p.snapshot);
-		if (ret)
-			break;
-	}
-	bch2_trans_iter_exit(trans, &new_iter);
-	bch2_trans_iter_exit(trans, &old_iter);
-	darray_exit(&s);
-
-	return ret;
-}
-
-int bch2_trans_update_extent_overwrite(struct btree_trans *trans,
-				       struct btree_iter *iter,
-				       enum btree_update_flags flags,
-				       struct bkey_s_c old,
-				       struct bkey_s_c new)
-{
-	enum btree_id btree_id = iter->btree_id;
-	struct bkey_i *update;
-	struct bpos new_start = bkey_start_pos(new.k);
-	bool front_split = bkey_lt(bkey_start_pos(old.k), new_start);
-	bool back_split  = bkey_gt(old.k->p, new.k->p);
-	int ret = 0, compressed_sectors;
-
-	/*
-	 * If we're going to be splitting a compressed extent, note it
-	 * so that __bch2_trans_commit() can increase our disk
-	 * reservation:
-	 */
-	if (((front_split && back_split) ||
-	     ((front_split || back_split) && old.k->p.snapshot != new.k->p.snapshot)) &&
-	    (compressed_sectors = bch2_bkey_sectors_compressed(old)))
-		trans->extra_journal_res += compressed_sectors;
-
-	if (front_split) {
-		update = bch2_bkey_make_mut_noupdate(trans, old);
-		if ((ret = PTR_ERR_OR_ZERO(update)))
-			return ret;
-
-		bch2_cut_back(new_start, update);
-
-		ret =   bch2_insert_snapshot_whiteouts(trans, btree_id,
-					old.k->p, update->k.p) ?:
-			bch2_btree_insert_nonextent(trans, btree_id, update,
-					BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
-		if (ret)
-			return ret;
-	}
-
-	/* If we're overwriting in a different snapshot - middle split: */
-	if (old.k->p.snapshot != new.k->p.snapshot &&
-	    (front_split || back_split)) {
-		update = bch2_bkey_make_mut_noupdate(trans, old);
-		if ((ret = PTR_ERR_OR_ZERO(update)))
-			return ret;
-
-		bch2_cut_front(new_start, update);
-		bch2_cut_back(new.k->p, update);
-
-		ret =   bch2_insert_snapshot_whiteouts(trans, btree_id,
-					old.k->p, update->k.p) ?:
-			bch2_btree_insert_nonextent(trans, btree_id, update,
-					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
-		if (ret)
-			return ret;
-	}
-
-	if (bkey_le(old.k->p, new.k->p)) {
-		update = bch2_trans_kmalloc(trans, sizeof(*update));
-		if ((ret = PTR_ERR_OR_ZERO(update)))
-			return ret;
-
-		bkey_init(&update->k);
-		update->k.p = old.k->p;
-		update->k.p.snapshot = new.k->p.snapshot;
-
-		if (new.k->p.snapshot != old.k->p.snapshot) {
-			update->k.type = KEY_TYPE_whiteout;
-		} else if (btree_type_has_snapshots(btree_id)) {
-			ret = need_whiteout_for_snapshot(trans, btree_id, update->k.p);
-			if (ret < 0)
-				return ret;
-			if (ret)
-				update->k.type = KEY_TYPE_whiteout;
-		}
-
-		ret = bch2_btree_insert_nonextent(trans, btree_id, update,
-					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
-		if (ret)
-			return ret;
-	}
-
-	if (back_split) {
-		update = bch2_bkey_make_mut_noupdate(trans, old);
-		if ((ret = PTR_ERR_OR_ZERO(update)))
-			return ret;
-
-		bch2_cut_front(new.k->p, update);
-
-		ret = bch2_trans_update_by_path(trans, iter->path, update,
-					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
-					  flags, _RET_IP_);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-
-static 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 bkey_s_c k;
-	enum btree_id btree_id = orig_iter->btree_id;
-	int ret = 0;
-
-	bch2_trans_iter_init(trans, &iter, btree_id, bkey_start_pos(&insert->k),
-			     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;
-		}
-
-		goto next;
-	}
-
-	while (bkey_gt(insert->k.p, bkey_start_pos(k.k))) {
-		bool done = bkey_lt(insert->k.p, k.k->p);
-
-		ret = bch2_trans_update_extent_overwrite(trans, &iter, flags, k, bkey_i_to_s_c(insert));
-		if (ret)
-			goto err;
-
-		if (done)
-			goto out;
-next:
-		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;
-	}
-
-	if (bch2_bkey_maybe_mergable(&insert->k, k.k)) {
-		ret = extent_back_merge(trans, &iter, insert, k);
-		if (ret)
-			goto err;
-	}
-out:
-	if (!bkey_deleted(&insert->k))
-		ret = bch2_btree_insert_nonextent(trans, btree_id, insert, flags);
-err:
-	bch2_trans_iter_exit(trans, &iter);
-
-	return ret;
-}
-
-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_path *btree_path;
-	struct bkey k;
-	int ret;
-
-	btree_path = bch2_path_get(trans, path->btree_id, path->pos, 1, 0,
-				   BTREE_ITER_INTENT, _THIS_IP_);
-	ret = bch2_btree_path_traverse(trans, btree_path, 0);
-	if (ret)
-		goto out;
-
-	/*
-	 * The old key in the insert entry might actually refer to an existing
-	 * key in the btree that has been deleted from cache and not yet
-	 * flushed. Check for this and skip the flush so we don't run triggers
-	 * against a stale key.
-	 */
-	bch2_btree_path_peek_slot_exact(btree_path, &k);
-	if (!bkey_deleted(&k))
-		goto out;
-
-	i->key_cache_already_flushed = true;
-	i->flags |= BTREE_TRIGGER_NORUN;
-
-	btree_path_set_should_be_locked(btree_path);
-	ret = bch2_trans_update_by_path(trans, btree_path, i->k, flags, ip);
-out:
-	bch2_path_put(trans, btree_path, true);
-	return ret;
-}
-
-static 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,
-			  unsigned long ip)
-{
-	struct bch_fs *c = trans->c;
-	struct btree_insert_entry *i, n;
-	u64 seq = 0;
-	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));
-
-	/*
-	 * The transaction journal res hasn't been allocated at this point.
-	 * That occurs at commit time. Reuse the seq field to pass in the seq
-	 * of a prejournaled key.
-	 */
-	if (flags & BTREE_UPDATE_PREJOURNAL)
-		seq = trans->journal_res.seq;
-
-	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,
-		.seq		= seq,
-		.ip_allocated	= ip,
-	};
-
-#ifdef CONFIG_BCACHEFS_DEBUG
-	trans_for_each_update(trans, i)
-		BUG_ON(i != trans->updates &&
-		       btree_insert_entry_cmp(i - 1, i) >= 0);
-#endif
-
-	/*
-	 * 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) {
-		cmp = btree_insert_entry_cmp(&n, i);
-		if (cmp <= 0)
-			break;
-	}
-
-	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->seq		= n.seq;
-		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;
-			}
-		}
-	}
-
-	__btree_path_get(i->path, true);
-
-	/*
-	 * 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))
-		return flush_new_cached_update(trans, path, i, flags, ip);
-
-	return 0;
-}
-
-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 (ret)
-			k->k.type = KEY_TYPE_whiteout;
-	}
-
-	/*
-	 * 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;
-
-			ck = (void *) iter->key_cache_path->l[0].b;
-
-			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);
-			}
-
-			btree_path_set_should_be_locked(iter->key_cache_path);
-		}
-
-		path = iter->key_cache_path;
-	}
-
-	return bch2_trans_update_by_path(trans, path, k, flags, _RET_IP_);
-}
-
-/*
- * Add a transaction update for a key that has already been journaled.
- */
-int __must_check bch2_trans_update_seq(struct btree_trans *trans, u64 seq,
-				       struct btree_iter *iter, struct bkey_i *k,
-				       enum btree_update_flags flags)
-{
-	trans->journal_res.seq = seq;
-	return bch2_trans_update(trans, iter, k, flags|BTREE_UPDATE_NOJOURNAL|
-						 BTREE_UPDATE_PREJOURNAL);
-}
-
-int __must_check bch2_trans_update_buffered(struct btree_trans *trans,
-					    enum btree_id btree,
-					    struct bkey_i *k)
-{
-	struct btree_write_buffered_key *i;
-	int ret;
-
-	EBUG_ON(trans->nr_wb_updates > trans->wb_updates_size);
-	EBUG_ON(k->k.u64s > BTREE_WRITE_BUFERED_U64s_MAX);
-
-	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;
-		}
-	}
-
-	if (!trans->wb_updates ||
-	    trans->nr_wb_updates == trans->wb_updates_size) {
-		struct btree_write_buffered_key *u;
-
-		if (trans->nr_wb_updates == trans->wb_updates_size) {
-			struct btree_transaction_stats *s = btree_trans_stats(trans);
-
-			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;
-
-		if (trans->nr_wb_updates)
-			memcpy(u, trans->wb_updates, trans->nr_wb_updates *
-			       sizeof(struct btree_write_buffered_key));
-		trans->wb_updates = u;
-	}
-
-	trans->wb_updates[trans->nr_wb_updates] = (struct btree_write_buffered_key) {
-		.btree	= btree,
-	};
-
-	bkey_copy(&trans->wb_updates[trans->nr_wb_updates].k, k);
-	trans->nr_wb_updates++;
-
-	return 0;
-}
-
-int bch2_bkey_get_empty_slot(struct btree_trans *trans, struct btree_iter *iter,
-			     enum btree_id btree, struct bpos end)
-{
-	struct bkey_s_c k;
-	int ret = 0;
-
-	bch2_trans_iter_init(trans, iter, btree, POS_MAX, BTREE_ITER_INTENT);
-	k = bch2_btree_iter_prev(iter);
-	ret = bkey_err(k);
-	if (ret)
-		goto err;
-
-	bch2_btree_iter_advance(iter);
-	k = bch2_btree_iter_peek_slot(iter);
-	ret = bkey_err(k);
-	if (ret)
-		goto err;
-
-	BUG_ON(k.k->type != KEY_TYPE_deleted);
-
-	if (bkey_gt(k.k->p, end)) {
-		ret = -BCH_ERR_ENOSPC_btree_slot;
-		goto err;
-	}
-
-	return 0;
-err:
-	bch2_trans_iter_exit(trans, iter);
-	return ret;
-}
-
-void bch2_trans_commit_hook(struct btree_trans *trans,
-			    struct btree_trans_commit_hook *h)
-{
-	h->next = trans->hooks;
-	trans->hooks = h;
-}
-
-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;
-	int ret;
-
-	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;
-
-	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;
-}
-
-/**
- * bch2_btree_insert - insert keys into the extent btree
- * @c:			pointer to struct bch_fs
- * @id:			btree to insert into
- * @insert_keys:	list of keys to insert
- * @hook:		insert callback
- */
-int bch2_btree_insert(struct bch_fs *c, enum btree_id id,
-		      struct bkey_i *k,
-		      struct disk_reservation *disk_res,
-		      u64 *journal_seq, int flags)
-{
-	return bch2_trans_do(c, disk_res, journal_seq, flags,
-			     __bch2_btree_insert(&trans, id, k, 0));
-}
-
-int bch2_btree_delete_extent_at(struct btree_trans *trans, struct btree_iter *iter,
-				unsigned len, unsigned update_flags)
-{
-	struct bkey_i *k;
-
-	k = bch2_trans_kmalloc(trans, sizeof(*k));
-	if (IS_ERR(k))
-		return PTR_ERR(k);
-
-	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_at_buffered(struct btree_trans *trans,
-				  enum btree_id btree, struct bpos pos)
-{
-	struct bkey_i *k;
-
-	k = bch2_trans_kmalloc(trans, sizeof(*k));
-	if (IS_ERR(k))
-		return PTR_ERR(k);
-
-	bkey_init(&k->k);
-	k->k.p = pos;
-	return bch2_trans_update_buffered(trans, btree, k);
-}
-
-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)
-{
-	u32 restart_count = trans->restart_count;
-	struct btree_iter iter;
-	struct bkey_s_c k;
-	int ret = 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);
-
-		/*
-		 * This could probably be more efficient for extents:
-		 */
-
-		/*
-		 * For extents, iter.pos won't necessarily be the same as
-		 * bkey_start_pos(k.k) (for non extents they always will be the
-		 * same). It's important that we delete starting from iter.pos
-		 * because the range we want to delete could start in the middle
-		 * of k.
-		 *
-		 * (bch2_btree_iter_peek() does guarantee that iter.pos >=
-		 * bkey_start_pos(k.k)).
-		 */
-		delete.k.p = iter.pos;
-
-		if (iter.flags & BTREE_ITER_IS_EXTENTS)
-			bch2_key_resize(&delete.k,
-					bpos_min(end, k.k->p).offset -
-					iter.pos.offset);
-
-		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);
-
-		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
-			ret = 0;
-		if (ret)
-			break;
-	}
-	bch2_trans_iter_exit(trans, &iter);
-
-	if (!ret && trans_was_restarted(trans, restart_count))
-		ret = -BCH_ERR_transaction_restart_nested;
-	return ret;
-}
-
-/*
- * bch_btree_delete_range - delete everything within a given range
- *
- * Range is a half open interval - [start, end)
- */
-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)
-{
-	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;
-}
-
-int bch2_btree_bit_mod(struct btree_trans *trans, enum btree_id btree,
-		       struct bpos pos, bool set)
-{
-	struct bkey_i *k;
-	int ret = 0;
-
-	k = bch2_trans_kmalloc_nomemzero(trans, sizeof(*k));
-	ret = PTR_ERR_OR_ZERO(k);
-	if (unlikely(ret))
-		return ret;
-
-	bkey_init(&k->k);
-	k->k.type = set ? KEY_TYPE_set : KEY_TYPE_deleted;
-	k->k.p = pos;
-
-	return bch2_trans_update_buffered(trans, btree, k);
-}
-
-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 ? -BCH_ERR_ENOMEM_trans_log_msg : 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;
-}
-
-static int
-__bch2_fs_log_msg(struct bch_fs *c, unsigned commit_flags, const char *fmt,
-		  va_list args)
-{
-	int ret;
-
-	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|commit_flags,
-			__bch2_trans_log_msg(&trans.extra_journal_entries, fmt, args));
-	}
-
-	return ret;
-}
-
-int bch2_fs_log_msg(struct bch_fs *c, const char *fmt, ...)
-{
-	va_list args;
-	int ret;
-
-	va_start(args, fmt);
-	ret = __bch2_fs_log_msg(c, 0, fmt, args);
-	va_end(args);
-	return ret;
-}
-
-/*
- * Use for logging messages during recovery to enable reserved space and avoid
- * blocking.
- */
-int bch2_journal_log_msg(struct bch_fs *c, const char *fmt, ...)
-{
-	va_list args;
-	int ret;
-
-	va_start(args, fmt);
-	ret = __bch2_fs_log_msg(c, BCH_WATERMARK_reclaim, fmt, args);
-	va_end(args);
-	return ret;
-}
diff --git a/fs/bcachefs/btree_update.c b/fs/bcachefs/btree_update.c
new file mode 100644
index 000000000000..366929da58a0
--- /dev/null
+++ b/fs/bcachefs/btree_update.c
@@ -0,0 +1,943 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "btree_update.h"
+#include "btree_iter.h"
+#include "btree_locking.h"
+#include "buckets.h"
+#include "debug.h"
+#include "errcode.h"
+#include "error.h"
+#include "extents.h"
+#include "keylist.h"
+#include "recovery.h"
+#include "subvolume.h"
+#include "trace.h"
+
+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 int __must_check
+bch2_trans_update_by_path(struct btree_trans *, struct btree_path *,
+			  struct bkey_i *, enum btree_update_flags,
+			  unsigned long ip);
+
+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) ||
+	    bch2_snapshot_is_leaf(trans->c, pos.snapshot))
+		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_noupdate(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_insert_snapshot_whiteouts(struct btree_trans *trans,
+				   enum btree_id id,
+				   struct bpos old_pos,
+				   struct bpos new_pos)
+{
+	struct bch_fs *c = trans->c;
+	struct btree_iter old_iter, new_iter = { NULL };
+	struct bkey_s_c old_k, new_k;
+	snapshot_id_list s;
+	struct bkey_i *update;
+	int ret;
+
+	if (!bch2_snapshot_has_children(c, old_pos.snapshot))
+		return 0;
+
+	darray_init(&s);
+
+	bch2_trans_iter_init(trans, &old_iter, id, old_pos,
+			     BTREE_ITER_NOT_EXTENTS|
+			     BTREE_ITER_ALL_SNAPSHOTS);
+	while ((old_k = bch2_btree_iter_prev(&old_iter)).k &&
+	       !(ret = bkey_err(old_k)) &&
+	       bkey_eq(old_pos, old_k.k->p)) {
+		struct bpos whiteout_pos =
+			SPOS(new_pos.inode, new_pos.offset, old_k.k->p.snapshot);;
+
+		if (!bch2_snapshot_is_ancestor(c, old_k.k->p.snapshot, old_pos.snapshot) ||
+		    snapshot_list_has_ancestor(c, &s, old_k.k->p.snapshot))
+			continue;
+
+		new_k = bch2_bkey_get_iter(trans, &new_iter, id, whiteout_pos,
+					   BTREE_ITER_NOT_EXTENTS|
+					   BTREE_ITER_INTENT);
+		ret = bkey_err(new_k);
+		if (ret)
+			break;
+
+		if (new_k.k->type == KEY_TYPE_deleted) {
+			update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
+			ret = PTR_ERR_OR_ZERO(update);
+			if (ret)
+				break;
+
+			bkey_init(&update->k);
+			update->k.p		= whiteout_pos;
+			update->k.type		= KEY_TYPE_whiteout;
+
+			ret = bch2_trans_update(trans, &new_iter, update,
+						BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+		}
+		bch2_trans_iter_exit(trans, &new_iter);
+
+		ret = snapshot_list_add(c, &s, old_k.k->p.snapshot);
+		if (ret)
+			break;
+	}
+	bch2_trans_iter_exit(trans, &new_iter);
+	bch2_trans_iter_exit(trans, &old_iter);
+	darray_exit(&s);
+
+	return ret;
+}
+
+int bch2_trans_update_extent_overwrite(struct btree_trans *trans,
+				       struct btree_iter *iter,
+				       enum btree_update_flags flags,
+				       struct bkey_s_c old,
+				       struct bkey_s_c new)
+{
+	enum btree_id btree_id = iter->btree_id;
+	struct bkey_i *update;
+	struct bpos new_start = bkey_start_pos(new.k);
+	bool front_split = bkey_lt(bkey_start_pos(old.k), new_start);
+	bool back_split  = bkey_gt(old.k->p, new.k->p);
+	int ret = 0, compressed_sectors;
+
+	/*
+	 * If we're going to be splitting a compressed extent, note it
+	 * so that __bch2_trans_commit() can increase our disk
+	 * reservation:
+	 */
+	if (((front_split && back_split) ||
+	     ((front_split || back_split) && old.k->p.snapshot != new.k->p.snapshot)) &&
+	    (compressed_sectors = bch2_bkey_sectors_compressed(old)))
+		trans->extra_journal_res += compressed_sectors;
+
+	if (front_split) {
+		update = bch2_bkey_make_mut_noupdate(trans, old);
+		if ((ret = PTR_ERR_OR_ZERO(update)))
+			return ret;
+
+		bch2_cut_back(new_start, update);
+
+		ret =   bch2_insert_snapshot_whiteouts(trans, btree_id,
+					old.k->p, update->k.p) ?:
+			bch2_btree_insert_nonextent(trans, btree_id, update,
+					BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
+		if (ret)
+			return ret;
+	}
+
+	/* If we're overwriting in a different snapshot - middle split: */
+	if (old.k->p.snapshot != new.k->p.snapshot &&
+	    (front_split || back_split)) {
+		update = bch2_bkey_make_mut_noupdate(trans, old);
+		if ((ret = PTR_ERR_OR_ZERO(update)))
+			return ret;
+
+		bch2_cut_front(new_start, update);
+		bch2_cut_back(new.k->p, update);
+
+		ret =   bch2_insert_snapshot_whiteouts(trans, btree_id,
+					old.k->p, update->k.p) ?:
+			bch2_btree_insert_nonextent(trans, btree_id, update,
+					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
+		if (ret)
+			return ret;
+	}
+
+	if (bkey_le(old.k->p, new.k->p)) {
+		update = bch2_trans_kmalloc(trans, sizeof(*update));
+		if ((ret = PTR_ERR_OR_ZERO(update)))
+			return ret;
+
+		bkey_init(&update->k);
+		update->k.p = old.k->p;
+		update->k.p.snapshot = new.k->p.snapshot;
+
+		if (new.k->p.snapshot != old.k->p.snapshot) {
+			update->k.type = KEY_TYPE_whiteout;
+		} else if (btree_type_has_snapshots(btree_id)) {
+			ret = need_whiteout_for_snapshot(trans, btree_id, update->k.p);
+			if (ret < 0)
+				return ret;
+			if (ret)
+				update->k.type = KEY_TYPE_whiteout;
+		}
+
+		ret = bch2_btree_insert_nonextent(trans, btree_id, update,
+					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags);
+		if (ret)
+			return ret;
+	}
+
+	if (back_split) {
+		update = bch2_bkey_make_mut_noupdate(trans, old);
+		if ((ret = PTR_ERR_OR_ZERO(update)))
+			return ret;
+
+		bch2_cut_front(new.k->p, update);
+
+		ret = bch2_trans_update_by_path(trans, iter->path, update,
+					  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+					  flags, _RET_IP_);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static 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 bkey_s_c k;
+	enum btree_id btree_id = orig_iter->btree_id;
+	int ret = 0;
+
+	bch2_trans_iter_init(trans, &iter, btree_id, bkey_start_pos(&insert->k),
+			     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;
+		}
+
+		goto next;
+	}
+
+	while (bkey_gt(insert->k.p, bkey_start_pos(k.k))) {
+		bool done = bkey_lt(insert->k.p, k.k->p);
+
+		ret = bch2_trans_update_extent_overwrite(trans, &iter, flags, k, bkey_i_to_s_c(insert));
+		if (ret)
+			goto err;
+
+		if (done)
+			goto out;
+next:
+		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;
+	}
+
+	if (bch2_bkey_maybe_mergable(&insert->k, k.k)) {
+		ret = extent_back_merge(trans, &iter, insert, k);
+		if (ret)
+			goto err;
+	}
+out:
+	if (!bkey_deleted(&insert->k))
+		ret = bch2_btree_insert_nonextent(trans, btree_id, insert, flags);
+err:
+	bch2_trans_iter_exit(trans, &iter);
+
+	return ret;
+}
+
+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_path *btree_path;
+	struct bkey k;
+	int ret;
+
+	btree_path = bch2_path_get(trans, path->btree_id, path->pos, 1, 0,
+				   BTREE_ITER_INTENT, _THIS_IP_);
+	ret = bch2_btree_path_traverse(trans, btree_path, 0);
+	if (ret)
+		goto out;
+
+	/*
+	 * The old key in the insert entry might actually refer to an existing
+	 * key in the btree that has been deleted from cache and not yet
+	 * flushed. Check for this and skip the flush so we don't run triggers
+	 * against a stale key.
+	 */
+	bch2_btree_path_peek_slot_exact(btree_path, &k);
+	if (!bkey_deleted(&k))
+		goto out;
+
+	i->key_cache_already_flushed = true;
+	i->flags |= BTREE_TRIGGER_NORUN;
+
+	btree_path_set_should_be_locked(btree_path);
+	ret = bch2_trans_update_by_path(trans, btree_path, i->k, flags, ip);
+out:
+	bch2_path_put(trans, btree_path, true);
+	return ret;
+}
+
+static 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,
+			  unsigned long ip)
+{
+	struct bch_fs *c = trans->c;
+	struct btree_insert_entry *i, n;
+	u64 seq = 0;
+	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));
+
+	/*
+	 * The transaction journal res hasn't been allocated at this point.
+	 * That occurs at commit time. Reuse the seq field to pass in the seq
+	 * of a prejournaled key.
+	 */
+	if (flags & BTREE_UPDATE_PREJOURNAL)
+		seq = trans->journal_res.seq;
+
+	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,
+		.seq		= seq,
+		.ip_allocated	= ip,
+	};
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+	trans_for_each_update(trans, i)
+		BUG_ON(i != trans->updates &&
+		       btree_insert_entry_cmp(i - 1, i) >= 0);
+#endif
+
+	/*
+	 * 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) {
+		cmp = btree_insert_entry_cmp(&n, i);
+		if (cmp <= 0)
+			break;
+	}
+
+	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->seq		= n.seq;
+		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;
+			}
+		}
+	}
+
+	__btree_path_get(i->path, true);
+
+	/*
+	 * 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))
+		return flush_new_cached_update(trans, path, i, flags, ip);
+
+	return 0;
+}
+
+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 (ret)
+			k->k.type = KEY_TYPE_whiteout;
+	}
+
+	/*
+	 * 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;
+
+			ck = (void *) iter->key_cache_path->l[0].b;
+
+			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);
+			}
+
+			btree_path_set_should_be_locked(iter->key_cache_path);
+		}
+
+		path = iter->key_cache_path;
+	}
+
+	return bch2_trans_update_by_path(trans, path, k, flags, _RET_IP_);
+}
+
+/*
+ * Add a transaction update for a key that has already been journaled.
+ */
+int __must_check bch2_trans_update_seq(struct btree_trans *trans, u64 seq,
+				       struct btree_iter *iter, struct bkey_i *k,
+				       enum btree_update_flags flags)
+{
+	trans->journal_res.seq = seq;
+	return bch2_trans_update(trans, iter, k, flags|BTREE_UPDATE_NOJOURNAL|
+						 BTREE_UPDATE_PREJOURNAL);
+}
+
+int __must_check bch2_trans_update_buffered(struct btree_trans *trans,
+					    enum btree_id btree,
+					    struct bkey_i *k)
+{
+	struct btree_write_buffered_key *i;
+	int ret;
+
+	EBUG_ON(trans->nr_wb_updates > trans->wb_updates_size);
+	EBUG_ON(k->k.u64s > BTREE_WRITE_BUFERED_U64s_MAX);
+
+	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;
+		}
+	}
+
+	if (!trans->wb_updates ||
+	    trans->nr_wb_updates == trans->wb_updates_size) {
+		struct btree_write_buffered_key *u;
+
+		if (trans->nr_wb_updates == trans->wb_updates_size) {
+			struct btree_transaction_stats *s = btree_trans_stats(trans);
+
+			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;
+
+		if (trans->nr_wb_updates)
+			memcpy(u, trans->wb_updates, trans->nr_wb_updates *
+			       sizeof(struct btree_write_buffered_key));
+		trans->wb_updates = u;
+	}
+
+	trans->wb_updates[trans->nr_wb_updates] = (struct btree_write_buffered_key) {
+		.btree	= btree,
+	};
+
+	bkey_copy(&trans->wb_updates[trans->nr_wb_updates].k, k);
+	trans->nr_wb_updates++;
+
+	return 0;
+}
+
+int bch2_bkey_get_empty_slot(struct btree_trans *trans, struct btree_iter *iter,
+			     enum btree_id btree, struct bpos end)
+{
+	struct bkey_s_c k;
+	int ret = 0;
+
+	bch2_trans_iter_init(trans, iter, btree, POS_MAX, BTREE_ITER_INTENT);
+	k = bch2_btree_iter_prev(iter);
+	ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	bch2_btree_iter_advance(iter);
+	k = bch2_btree_iter_peek_slot(iter);
+	ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	BUG_ON(k.k->type != KEY_TYPE_deleted);
+
+	if (bkey_gt(k.k->p, end)) {
+		ret = -BCH_ERR_ENOSPC_btree_slot;
+		goto err;
+	}
+
+	return 0;
+err:
+	bch2_trans_iter_exit(trans, iter);
+	return ret;
+}
+
+void bch2_trans_commit_hook(struct btree_trans *trans,
+			    struct btree_trans_commit_hook *h)
+{
+	h->next = trans->hooks;
+	trans->hooks = h;
+}
+
+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;
+	int ret;
+
+	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;
+
+	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;
+}
+
+/**
+ * bch2_btree_insert - insert keys into the extent btree
+ * @c:			pointer to struct bch_fs
+ * @id:			btree to insert into
+ * @insert_keys:	list of keys to insert
+ * @hook:		insert callback
+ */
+int bch2_btree_insert(struct bch_fs *c, enum btree_id id,
+		      struct bkey_i *k,
+		      struct disk_reservation *disk_res,
+		      u64 *journal_seq, int flags)
+{
+	return bch2_trans_do(c, disk_res, journal_seq, flags,
+			     __bch2_btree_insert(&trans, id, k, 0));
+}
+
+int bch2_btree_delete_extent_at(struct btree_trans *trans, struct btree_iter *iter,
+				unsigned len, unsigned update_flags)
+{
+	struct bkey_i *k;
+
+	k = bch2_trans_kmalloc(trans, sizeof(*k));
+	if (IS_ERR(k))
+		return PTR_ERR(k);
+
+	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_at_buffered(struct btree_trans *trans,
+				  enum btree_id btree, struct bpos pos)
+{
+	struct bkey_i *k;
+
+	k = bch2_trans_kmalloc(trans, sizeof(*k));
+	if (IS_ERR(k))
+		return PTR_ERR(k);
+
+	bkey_init(&k->k);
+	k->k.p = pos;
+	return bch2_trans_update_buffered(trans, btree, k);
+}
+
+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)
+{
+	u32 restart_count = trans->restart_count;
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	int ret = 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);
+
+		/*
+		 * This could probably be more efficient for extents:
+		 */
+
+		/*
+		 * For extents, iter.pos won't necessarily be the same as
+		 * bkey_start_pos(k.k) (for non extents they always will be the
+		 * same). It's important that we delete starting from iter.pos
+		 * because the range we want to delete could start in the middle
+		 * of k.
+		 *
+		 * (bch2_btree_iter_peek() does guarantee that iter.pos >=
+		 * bkey_start_pos(k.k)).
+		 */
+		delete.k.p = iter.pos;
+
+		if (iter.flags & BTREE_ITER_IS_EXTENTS)
+			bch2_key_resize(&delete.k,
+					bpos_min(end, k.k->p).offset -
+					iter.pos.offset);
+
+		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);
+
+		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+			ret = 0;
+		if (ret)
+			break;
+	}
+	bch2_trans_iter_exit(trans, &iter);
+
+	if (!ret && trans_was_restarted(trans, restart_count))
+		ret = -BCH_ERR_transaction_restart_nested;
+	return ret;
+}
+
+/*
+ * bch_btree_delete_range - delete everything within a given range
+ *
+ * Range is a half open interval - [start, end)
+ */
+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)
+{
+	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;
+}
+
+int bch2_btree_bit_mod(struct btree_trans *trans, enum btree_id btree,
+		       struct bpos pos, bool set)
+{
+	struct bkey_i *k;
+	int ret = 0;
+
+	k = bch2_trans_kmalloc_nomemzero(trans, sizeof(*k));
+	ret = PTR_ERR_OR_ZERO(k);
+	if (unlikely(ret))
+		return ret;
+
+	bkey_init(&k->k);
+	k->k.type = set ? KEY_TYPE_set : KEY_TYPE_deleted;
+	k->k.p = pos;
+
+	return bch2_trans_update_buffered(trans, btree, k);
+}
+
+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 ? -BCH_ERR_ENOMEM_trans_log_msg : 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;
+}
+
+static int
+__bch2_fs_log_msg(struct bch_fs *c, unsigned commit_flags, const char *fmt,
+		  va_list args)
+{
+	int ret;
+
+	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|commit_flags,
+			__bch2_trans_log_msg(&trans.extra_journal_entries, fmt, args));
+	}
+
+	return ret;
+}
+
+int bch2_fs_log_msg(struct bch_fs *c, const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = __bch2_fs_log_msg(c, 0, fmt, args);
+	va_end(args);
+	return ret;
+}
+
+/*
+ * Use for logging messages during recovery to enable reserved space and avoid
+ * blocking.
+ */
+int bch2_journal_log_msg(struct bch_fs *c, const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = __bch2_fs_log_msg(c, BCH_WATERMARK_reclaim, fmt, args);
+	va_end(args);
+	return ret;
+}