Update bcachefs sources to 14e9ac5016 bcachefs: btree_iter fastpath

39 files changed, 928 insertions, 517 deletions

diff --git a/.bcachefs_revision b/.bcachefs_revision
index 8bc4e35..d2d0c51 100644
--- a/.bcachefs_revision
+++ b/.bcachefs_revision
@@ -1 +1 @@
-43e3159567958ea70c8a95d98fdb6e881153a656
+14e9ac5016803fc63c1216608c866bef16b4053e
diff --git a/cmd_migrate.c b/cmd_migrate.c
index bf8f0be..82fa0f1 100644
--- a/cmd_migrate.c
+++ b/cmd_migrate.c
@@ -250,7 +250,6 @@ static void write_data(struct bch_fs *c,
 {
 	struct disk_reservation res;
 	struct bch_write_op op;
-	struct bch_write_bio bio;
 	struct bio_vec bv;
 	struct closure cl;
 
@@ -259,15 +258,15 @@ static void write_data(struct bch_fs *c,
 
 	closure_init_stack(&cl);
 
-	bio_init(&bio.bio, &bv, 1);
-	bio.bio.bi_iter.bi_size	= len;
-	bch2_bio_map(&bio.bio, buf);
+	bio_init(&op.wbio.bio, &bv, 1);
+	op.wbio.bio.bi_iter.bi_size = len;
+	bch2_bio_map(&op.wbio.bio, buf);
 
 	int ret = bch2_disk_reservation_get(c, &res, len >> 9, 0);
 	if (ret)
 		die("error reserving space in new filesystem: %s", strerror(-ret));
 
-	bch2_write_op_init(&op, c, &bio, res, c->write_points,
+	bch2_write_op_init(&op, c, res, c->write_points,
 			   POS(dst_inode->inum, dst_offset >> 9), NULL, 0);
 	closure_call(&op.cl, bch2_write, NULL, &cl);
 	closure_sync(&cl);
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index e5c31a6..915a6f8 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -166,4 +166,8 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
 #define flush_cache_vmap(start, end)		do { } while (0)
 #define flush_cache_vunmap(start, end)		do { } while (0)
 
+#ifdef __x86_64
+#define CONFIG_X86_64	y
+#endif
+
 #endif /* _TOOLS_LINUX_COMPILER_H */
diff --git a/include/linux/mempool.h b/include/linux/mempool.h
index ddf6f94..37d8149 100644
--- a/include/linux/mempool.h
+++ b/include/linux/mempool.h
@@ -10,8 +10,14 @@
 
 struct kmem_cache;
 
+typedef void * (mempool_alloc_t)(gfp_t gfp_mask, void *pool_data);
+typedef void (mempool_free_t)(void *element, void *pool_data);
+
 typedef struct mempool_s {
-	size_t		elem_size;
+	size_t			elem_size;
+	void			*pool_data;
+	mempool_alloc_t		*alloc;
+	mempool_free_t		*free;
 } mempool_t;
 
 static inline bool mempool_initialized(mempool_t *pool)
@@ -60,24 +66,22 @@ static inline int mempool_init_kmalloc_pool(mempool_t *pool, int min_nr, size_t
 	return 0;
 }
 
-static inline mempool_t *mempool_create_kmalloc_pool(int min_nr, size_t size)
-{
-	mempool_t *pool = malloc(sizeof(*pool));
-	pool->elem_size = size;
-	return pool;
-}
-
 static inline int mempool_init_page_pool(mempool_t *pool, int min_nr, int order)
 {
 	pool->elem_size = PAGE_SIZE << order;
 	return 0;
 }
 
-static inline mempool_t *mempool_create_page_pool(int min_nr, int order)
+static inline int mempool_init(mempool_t *pool, int min_nr,
+			       mempool_alloc_t *alloc_fn,
+			       mempool_free_t *free_fn,
+			       void *pool_data)
 {
-	mempool_t *pool = malloc(sizeof(*pool));
-	pool->elem_size = PAGE_SIZE << order;
-	return pool;
+	pool->elem_size = (size_t) pool_data;
+	pool->pool_data	= pool_data;
+	pool->alloc	= alloc_fn;
+	pool->free	= free_fn;
+	return 0;
 }
 
 #endif /* _LINUX_MEMPOOL_H */
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 58fb73e..d0d8790 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -43,9 +43,6 @@ static inline void *krealloc(void *old, size_t size, gfp_t flags)
 #define kcalloc(n, size, flags)		calloc(n, size)
 #define kmalloc_array(n, size, flags)	calloc(n, size)
 
-#define vmalloc(size)			malloc(size)
-#define vzalloc(size)			calloc(1, size)
-
 #define kfree(p)			free(p)
 #define kvfree(p)			free(p)
 #define kzfree(p)			free(p)
@@ -89,8 +86,6 @@ do {							\
 #define VM_NO_GUARD		0x00000040      /* don't add guard page */
 #define VM_KASAN		0x00000080      /* has allocated kasan shadow memory */
 
-#define PAGE_KERNEL		0
-
 static inline void vunmap(const void *addr) {}
 
 static inline void *vmap(struct page **pages, unsigned int count,
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index eb6284d..debdced 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -1,8 +1,41 @@
 #ifndef __TOOLS_LINUX_VMALLOC_H
 #define __TOOLS_LINUX_VMALLOC_H
 
-#define vmalloc(size)		malloc(size)
-#define __vmalloc(size, flags, prot)	malloc(size)
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include "tools-util.h"
+
+#define PAGE_KERNEL		0
+#define PAGE_KERNEL_EXEC	1
+
 #define vfree(p)		free(p)
 
+static inline void *__vmalloc(unsigned long size, gfp_t gfp_mask, unsigned prot)
+{
+	void *p = aligned_alloc(PAGE_SIZE, size);
+
+	if (p && prot == PAGE_KERNEL_EXEC) {
+		if (mprotect(p, size, PROT_READ|PROT_WRITE|PROT_EXEC)) {
+			vfree(p);
+			p = NULL;
+		}
+	}
+
+	if (p && (gfp_mask & __GFP_ZERO))
+		memset(p, 0, size);
+
+	return p;
+}
+
+static inline void *vmalloc(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
+}
+
+static inline void *vzalloc(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL|__GFP_ZERO, PAGE_KERNEL);
+}
+
 #endif /* __TOOLS_LINUX_VMALLOC_H */
diff --git a/libbcachefs/alloc.c b/libbcachefs/alloc.c
index a12c5d3..36dc947 100644
--- a/libbcachefs/alloc.c
+++ b/libbcachefs/alloc.c
@@ -361,7 +361,7 @@ static int __bch2_alloc_write_key(struct bch_fs *c, struct bch_dev *ca,
 				  struct bucket *g, struct btree_iter *iter,
 				  u64 *journal_seq)
 {
-	struct bucket_mark m = READ_ONCE(g->mark);
+	struct bucket_mark m;
 	__BKEY_PADDED(k, DIV_ROUND_UP(sizeof(struct bch_alloc), 8)) alloc_key;
 	struct bkey_i_alloc *a;
 	u8 *d;
@@ -374,6 +374,8 @@ static int __bch2_alloc_write_key(struct bch_fs *c, struct bch_dev *ca,
 		if (ret)
 			break;
 
+		/* read mark under btree node lock: */
+		m = READ_ONCE(g->mark);
 		a = bkey_alloc_init(&alloc_key.k);
 		a->k.p		= iter->pos;
 		a->v.fields	= 0;
@@ -407,8 +409,6 @@ int bch2_alloc_replay_key(struct bch_fs *c, struct bpos pos)
 	struct btree_iter iter;
 	int ret;
 
-	lockdep_assert_held(&c->state_lock);
-
 	if (pos.inode >= c->sb.nr_devices || !c->devs[pos.inode])
 		return 0;
 
diff --git a/libbcachefs/bcachefs.h b/libbcachefs/bcachefs.h
index 9d04e89..4d0fc62 100644
--- a/libbcachefs/bcachefs.h
+++ b/libbcachefs/bcachefs.h
@@ -725,6 +725,10 @@ struct bch_fs {
 	struct work_struct	read_retry_work;
 	spinlock_t		read_retry_lock;
 
+	struct bio_list		btree_write_error_list;
+	struct work_struct	btree_write_error_work;
+	spinlock_t		btree_write_error_lock;
+
 	/* ERRORS */
 	struct list_head	fsck_errors;
 	struct mutex		fsck_error_lock;
diff --git a/libbcachefs/bcachefs_format.h b/libbcachefs/bcachefs_format.h
index 3f6d51a..125b6fa 100644
--- a/libbcachefs/bcachefs_format.h
+++ b/libbcachefs/bcachefs_format.h
@@ -1082,7 +1082,8 @@ struct jset_entry {
 	__le16			u64s;
 	__u8			btree_id;
 	__u8			level;
-	__le32			flags; /* designates what this jset holds */
+	__u8			type; /* designates what this jset holds */
+	__u8			pad[3];
 
 	union {
 		struct bkey_i	start[0];
@@ -1092,7 +1093,6 @@ struct jset_entry {
 
 #define JSET_KEYS_U64s	(sizeof(struct jset_entry) / sizeof(__u64))
 
-LE32_BITMASK(JOURNAL_ENTRY_TYPE,	struct jset_entry, flags, 0, 8);
 enum {
 	JOURNAL_ENTRY_BTREE_KEYS		= 0,
 	JOURNAL_ENTRY_BTREE_ROOT		= 1,
diff --git a/libbcachefs/bkey.c b/libbcachefs/bkey.c
index b9ceb6e..cc76257 100644
--- a/libbcachefs/bkey.c
+++ b/libbcachefs/bkey.c
@@ -791,11 +791,9 @@ static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
 			      unsigned dst_offset, unsigned dst_size,
 			      bool *eax_zeroed)
 {
-	unsigned byte = format->key_u64s * sizeof(u64);
 	unsigned bits = format->bits_per_field[field];
 	u64 offset = format->field_offset[field];
-	unsigned i, bit_offset = 0;
-	unsigned shl, shr;
+	unsigned i, byte, bit_offset, align, shl, shr;
 
 	if (!bits && !offset) {
 		if (!*eax_zeroed) {
@@ -842,11 +840,12 @@ static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
 		return out;
 	}
 
+	bit_offset = format->key_u64s * 64;
 	for (i = 0; i <= field; i++)
-		bit_offset += format->bits_per_field[i];
+		bit_offset -= format->bits_per_field[i];
 
-	byte -= DIV_ROUND_UP(bit_offset, 8);
-	bit_offset = round_up(bit_offset, 8) - bit_offset;
+	byte = bit_offset / 8;
+	bit_offset -= byte * 8;
 
 	*eax_zeroed = false;
 
@@ -857,6 +856,12 @@ static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
 		/* movzx eax, WORD PTR [rsi + imm8] */
 		I4(0x0f, 0xb7, 0x46, byte);
 	} else if (bit_offset + bits <= 32) {
+		align = min(4 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 3);
+		byte -= align;
+		bit_offset += align * 8;
+
+		BUG_ON(bit_offset + bits > 32);
+
 		/* mov eax, [rsi + imm8] */
 		I3(0x8b, 0x46, byte);
 
@@ -874,6 +879,12 @@ static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
 			out += 4;
 		}
 	} else if (bit_offset + bits <= 64) {
+		align = min(8 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 7);
+		byte -= align;
+		bit_offset += align * 8;
+
+		BUG_ON(bit_offset + bits > 64);
+
 		/* mov rax, [rsi + imm8] */
 		I4(0x48, 0x8b, 0x46, byte);
 
@@ -890,6 +901,12 @@ static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
 			I4(0x48, 0xc1, 0xe8, shr);
 		}
 	} else {
+		align = min(4 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 3);
+		byte -= align;
+		bit_offset += align * 8;
+
+		BUG_ON(bit_offset + bits > 96);
+
 		/* mov rax, [rsi + byte] */
 		I4(0x48, 0x8b, 0x46, byte);
 
diff --git a/libbcachefs/btree_cache.c b/libbcachefs/btree_cache.c
index bdbe21a..d619f37 100644
--- a/libbcachefs/btree_cache.c
+++ b/libbcachefs/btree_cache.c
@@ -41,7 +41,7 @@ static void __mca_data_free(struct bch_fs *c, struct btree *b)
 {
 	EBUG_ON(btree_node_write_in_flight(b));
 
-	free_pages((unsigned long) b->data, btree_page_order(c));
+	kvpfree(b->data, btree_bytes(c));
 	b->data = NULL;
 	bch2_btree_keys_free(b);
 }
@@ -53,8 +53,6 @@ static void mca_data_free(struct bch_fs *c, struct btree *b)
 	list_move(&b->list, &c->btree_cache_freed);
 }
 
-#define PTR_HASH(_k)	(bkey_i_to_extent_c(_k)->v._data[0])
-
 static const struct rhashtable_params bch_btree_cache_params = {
 	.head_offset	= offsetof(struct btree, hash),
 	.key_offset	= offsetof(struct btree, key.v),
@@ -63,20 +61,18 @@ static const struct rhashtable_params bch_btree_cache_params = {
 
 static void mca_data_alloc(struct bch_fs *c, struct btree *b, gfp_t gfp)
 {
-	unsigned order = ilog2(btree_pages(c));
-
-	b->data = (void *) __get_free_pages(gfp, order);
+	b->data = kvpmalloc(btree_bytes(c), gfp);
 	if (!b->data)
 		goto err;
 
-	if (bch2_btree_keys_alloc(b, order, gfp))
+	if (bch2_btree_keys_alloc(b, btree_page_order(c), gfp))
 		goto err;
 
 	c->btree_cache_used++;
 	list_move(&b->list, &c->btree_cache_freeable);
 	return;
 err:
-	free_pages((unsigned long) b->data, order);
+	kvpfree(b->data, btree_bytes(c));
 	b->data = NULL;
 	list_move(&b->list, &c->btree_cache_freed);
 }
@@ -91,7 +87,6 @@ static struct btree *mca_bucket_alloc(struct bch_fs *c, gfp_t gfp)
 	six_lock_init(&b->lock);
 	INIT_LIST_HEAD(&b->list);
 	INIT_LIST_HEAD(&b->write_blocked);
-	INIT_LIST_HEAD(&b->reachable);
 
 	mca_data_alloc(c, b, gfp);
 	return b->data ? b : NULL;
@@ -101,10 +96,6 @@ static struct btree *mca_bucket_alloc(struct bch_fs *c, gfp_t gfp)
 
 void bch2_btree_node_hash_remove(struct bch_fs *c, struct btree *b)
 {
-	BUG_ON(btree_node_dirty(b));
-
-	b->nsets = 0;
-
 	rhashtable_remove_fast(&c->btree_cache_table, &b->hash,
 			       bch_btree_cache_params);
 
@@ -112,23 +103,27 @@ void bch2_btree_node_hash_remove(struct bch_fs *c, struct btree *b)
 	bkey_i_to_extent(&b->key)->v._data[0] = 0;
 }
 
+int __bch2_btree_node_hash_insert(struct bch_fs *c, struct btree *b)
+{
+	return rhashtable_lookup_insert_fast(&c->btree_cache_table, &b->hash,
+					     bch_btree_cache_params);
+}
+
 int bch2_btree_node_hash_insert(struct bch_fs *c, struct btree *b,
 		    unsigned level, enum btree_id id)
 {
 	int ret;
+
 	b->level	= level;
 	b->btree_id	= id;
 
-	ret = rhashtable_lookup_insert_fast(&c->btree_cache_table, &b->hash,
-					    bch_btree_cache_params);
-	if (ret)
-		return ret;
-
 	mutex_lock(&c->btree_cache_lock);
-	list_add(&b->list, &c->btree_cache);
+	ret = __bch2_btree_node_hash_insert(c, b);
+	if (!ret)
+		list_add(&b->list, &c->btree_cache);
 	mutex_unlock(&c->btree_cache_lock);
 
-	return 0;
+	return ret;
 }
 
 __flatten
@@ -155,8 +150,7 @@ static int __btree_node_reclaim(struct bch_fs *c, struct btree *b, bool flush)
 	if (!six_trylock_write(&b->lock))
 		goto out_unlock_intent;
 
-	if (btree_node_write_error(b) ||
-	    btree_node_noevict(b))
+	if (btree_node_noevict(b))
 		goto out_unlock;
 
 	if (!btree_node_may_write(b))
@@ -328,7 +322,7 @@ void bch2_fs_btree_exit(struct bch_fs *c)
 	if (c->verify_data)
 		list_move(&c->verify_data->list, &c->btree_cache);
 
-	free_pages((unsigned long) c->verify_ondisk, ilog2(btree_pages(c)));
+	kvpfree(c->verify_ondisk, btree_bytes(c));
 #endif
 
 	for (i = 0; i < BTREE_ID_NR; i++)
@@ -384,8 +378,7 @@ int bch2_fs_btree_init(struct bch_fs *c)
 #ifdef CONFIG_BCACHEFS_DEBUG
 	mutex_init(&c->verify_lock);
 
-	c->verify_ondisk = (void *)
-		__get_free_pages(GFP_KERNEL, ilog2(btree_pages(c)));
+	c->verify_ondisk = kvpmalloc(btree_bytes(c), GFP_KERNEL);
 	if (!c->verify_ondisk)
 		return -ENOMEM;
 
@@ -510,7 +503,7 @@ struct btree *bch2_btree_node_mem_alloc(struct bch_fs *c)
 	BUG_ON(!six_trylock_intent(&b->lock));
 	BUG_ON(!six_trylock_write(&b->lock));
 out_unlock:
-	BUG_ON(bkey_extent_is_data(&b->key.k) && PTR_HASH(&b->key));
+	BUG_ON(btree_node_hashed(b));
 	BUG_ON(btree_node_write_in_flight(b));
 
 	list_del_init(&b->list);
@@ -554,6 +547,12 @@ static noinline struct btree *bch2_btree_node_fill(struct btree_iter *iter,
 	struct bch_fs *c = iter->c;
 	struct btree *b;
 
+	/*
+	 * Parent node must be locked, else we could read in a btree node that's
+	 * been freed:
+	 */
+	BUG_ON(!btree_node_locked(iter, level + 1));
+
 	b = bch2_btree_node_mem_alloc(c);
 	if (IS_ERR(b))
 		return b;
diff --git a/libbcachefs/btree_cache.h b/libbcachefs/btree_cache.h
index ca8e319..ea53d2b 100644
--- a/libbcachefs/btree_cache.h
+++ b/libbcachefs/btree_cache.h
@@ -3,6 +3,7 @@
 
 #include "bcachefs.h"
 #include "btree_types.h"
+#include "extents.h"
 
 struct btree_iter;
 
@@ -11,6 +12,7 @@ extern const char * const bch2_btree_ids[];
 void bch2_recalc_btree_reserve(struct bch_fs *);
 
 void bch2_btree_node_hash_remove(struct bch_fs *, struct btree *);
+int __bch2_btree_node_hash_insert(struct bch_fs *, struct btree *);
 int bch2_btree_node_hash_insert(struct bch_fs *, struct btree *,
 				unsigned, enum btree_id);
 
@@ -28,6 +30,14 @@ void bch2_btree_node_prefetch(struct btree_iter *, const struct bkey_i *,
 void bch2_fs_btree_exit(struct bch_fs *);
 int bch2_fs_btree_init(struct bch_fs *);
 
+#define PTR_HASH(_k)	(bkey_i_to_extent_c(_k)->v._data[0])
+
+/* is btree node in hash table? */
+static inline bool btree_node_hashed(struct btree *b)
+{
+	return bkey_extent_is_data(&b->key.k) && PTR_HASH(&b->key);
+}
+
 #define for_each_cached_btree(_b, _c, _tbl, _iter, _pos)		\
 	for ((_tbl) = rht_dereference_rcu((_c)->btree_cache_table.tbl,	\
 					  &(_c)->btree_cache_table),	\
diff --git a/libbcachefs/btree_gc.c b/libbcachefs/btree_gc.c
index 815260b..376edaf 100644
--- a/libbcachefs/btree_gc.c
+++ b/libbcachefs/btree_gc.c
@@ -621,12 +621,10 @@ static void bch2_coalesce_nodes(struct btree *old_nodes[GC_MERGE_NODES],
 		bch2_btree_interior_update_will_free_node(c, as, old_nodes[i]);
 
 	/* Repack everything with @new_format and sort down to one bset */
-	for (i = 0; i < nr_old_nodes; i++) {
+	for (i = 0; i < nr_old_nodes; i++)
 		new_nodes[i] =
 			__bch2_btree_node_alloc_replacement(c, old_nodes[i],
-							    new_format, res);
-		list_add(&new_nodes[i]->reachable, &as->reachable_list);
-	}
+							    new_format, as, res);
 
 	/*
 	 * Conceptually we concatenate the nodes together and slice them
@@ -663,7 +661,6 @@ static void bch2_coalesce_nodes(struct btree *old_nodes[GC_MERGE_NODES],
 
 			set_btree_bset_end(n1, n1->set);
 
-			list_del_init(&n2->reachable);
 			six_unlock_write(&n2->lock);
 			bch2_btree_node_free_never_inserted(c, n2);
 			six_unlock_intent(&n2->lock);
@@ -796,7 +793,8 @@ static int bch2_coalesce_btree(struct bch_fs *c, enum btree_id btree_id)
 	memset(merge, 0, sizeof(merge));
 
 	__for_each_btree_node(&iter, c, btree_id, POS_MIN,
-			      U8_MAX, 0, BTREE_ITER_PREFETCH, b) {
+			      BTREE_MAX_DEPTH, 0,
+			      BTREE_ITER_PREFETCH, b) {
 		memmove(merge + 1, merge,
 			sizeof(merge) - sizeof(merge[0]));
 		memmove(lock_seq + 1, lock_seq,
diff --git a/libbcachefs/btree_io.c b/libbcachefs/btree_io.c
index 571a814..eeb546e 100644
--- a/libbcachefs/btree_io.c
+++ b/libbcachefs/btree_io.c
@@ -56,9 +56,9 @@ static void btree_bounce_free(struct bch_fs *c, unsigned order,
 			      bool used_mempool, void *p)
 {
 	if (used_mempool)
-		mempool_free(virt_to_page(p), &c->btree_bounce_pool);
+		mempool_free(p, &c->btree_bounce_pool);
 	else
-		free_pages((unsigned long) p, order);
+		vpfree(p, PAGE_SIZE << order);
 }
 
 static void *btree_bounce_alloc(struct bch_fs *c, unsigned order,
@@ -66,7 +66,7 @@ static void *btree_bounce_alloc(struct bch_fs *c, unsigned order,
 {
 	void *p;
 
-	BUG_ON(1 << order > btree_pages(c));
+	BUG_ON(order > btree_page_order(c));
 
 	*used_mempool = false;
 	p = (void *) __get_free_pages(__GFP_NOWARN|GFP_NOWAIT, order);
@@ -74,7 +74,7 @@ static void *btree_bounce_alloc(struct bch_fs *c, unsigned order,
 		return p;
 
 	*used_mempool = true;
-	return page_address(mempool_alloc(&c->btree_bounce_pool, GFP_NOIO));
+	return mempool_alloc(&c->btree_bounce_pool, GFP_NOIO);
 }
 
 typedef int (*sort_cmp_fn)(struct btree *,
@@ -1183,7 +1183,7 @@ void bch2_btree_node_read_done(struct bch_fs *c, struct btree *b,
 		if (bne->keys.seq == b->data->keys.seq)
 			goto err;
 
-	sorted = btree_bounce_alloc(c, ilog2(btree_pages(c)), &used_mempool);
+	sorted = btree_bounce_alloc(c, btree_page_order(c), &used_mempool);
 	sorted->keys.u64s = 0;
 
 	b->nr = btree_node_is_extents(b)
@@ -1199,7 +1199,7 @@ void bch2_btree_node_read_done(struct bch_fs *c, struct btree *b,
 
 	BUG_ON(b->nr.live_u64s != u64s);
 
-	btree_bounce_free(c, ilog2(btree_pages(c)), used_mempool, sorted);
+	btree_bounce_free(c, btree_page_order(c), used_mempool, sorted);
 
 	bch2_bset_build_aux_tree(b, b->set, false);
 
@@ -1344,50 +1344,100 @@ static void btree_node_write_done(struct bch_fs *c, struct btree *b)
 {
 	struct btree_write *w = btree_prev_write(b);
 
-	/*
-	 * Before calling bch2_btree_complete_write() - if the write errored, we
-	 * have to halt new journal writes before they see this btree node
-	 * write as completed:
-	 */
-	if (btree_node_write_error(b))
-		bch2_journal_halt(&c->journal);
-
 	bch2_btree_complete_write(c, b, w);
 	btree_node_io_unlock(b);
 }
 
-static void btree_node_write_endio(struct bio *bio)
+static void bch2_btree_node_write_error(struct bch_fs *c,
+					struct bch_write_bio *wbio)
 {
-	struct btree *b = bio->bi_private;
-	struct bch_write_bio *wbio = to_wbio(bio);
-	struct bch_fs *c	= wbio->c;
-	struct bio *orig	= wbio->split ? wbio->orig : NULL;
-	struct closure *cl	= !wbio->split ? wbio->cl : NULL;
-	struct bch_dev *ca	= wbio->ca;
+	struct btree *b		= wbio->bio.bi_private;
+	struct closure *cl	= wbio->cl;
+	__BKEY_PADDED(k, BKEY_BTREE_PTR_VAL_U64s_MAX) tmp;
+	struct bkey_i_extent *new_key;
+
+	bkey_copy(&tmp.k, &b->key);
+	new_key = bkey_i_to_extent(&tmp.k);
+
+	while (wbio->replicas_failed) {
+		unsigned idx = __fls(wbio->replicas_failed);
+
+		bch2_extent_drop_ptr_idx(extent_i_to_s(new_key), idx);
+		wbio->replicas_failed ^= 1 << idx;
+	}
+
+	if (!bch2_extent_nr_ptrs(extent_i_to_s_c(new_key)) ||
+	    bch2_btree_node_update_key(c, b, new_key)) {
+		set_btree_node_noevict(b);
+		bch2_fatal_error(c);
+	}
+
+	bio_put(&wbio->bio);
+	btree_node_write_done(c, b);
+	if (cl)
+		closure_put(cl);
+}
+
+void bch2_btree_write_error_work(struct work_struct *work)
+{
+	struct bch_fs *c = container_of(work, struct bch_fs,
+					btree_write_error_work);
+	struct bio *bio;
+
+	while (1) {
+		spin_lock_irq(&c->read_retry_lock);
+		bio = bio_list_pop(&c->read_retry_list);
+		spin_unlock_irq(&c->read_retry_lock);
 
-	if (bch2_dev_fatal_io_err_on(bio->bi_error, ca, "btree write") ||
+		if (!bio)
+			break;
+
+		bch2_btree_node_write_error(c, to_wbio(bio));
+	}
+}
+
+static void btree_node_write_endio(struct bio *bio)
+{
+	struct btree *b			= bio->bi_private;
+	struct bch_write_bio *wbio	= to_wbio(bio);
+	struct bch_write_bio *parent	= wbio->split ? wbio->parent : NULL;
+	struct bch_write_bio *orig	= parent ?: wbio;
+	struct closure *cl		= !wbio->split ? wbio->cl : NULL;
+	struct bch_fs *c		= wbio->c;
+	struct bch_dev *ca		= wbio->ca;
+
+	if (bch2_dev_nonfatal_io_err_on(bio->bi_error, ca, "btree write") ||
 	    bch2_meta_write_fault("btree"))
-		set_btree_node_write_error(b);
+		set_bit(wbio->ptr_idx, (unsigned long *) &orig->replicas_failed);
 
 	if (wbio->have_io_ref)
 		percpu_ref_put(&ca->io_ref);
 
-	if (wbio->bounce)
-		btree_bounce_free(c,
-			wbio->order,
-			wbio->used_mempool,
-			page_address(bio->bi_io_vec[0].bv_page));
-
-	if (wbio->put_bio)
+	if (parent) {
 		bio_put(bio);
+		bio_endio(&parent->bio);
+		return;
+	}
 
-	if (orig) {
-		bio_endio(orig);
-	} else {
-		btree_node_write_done(c, b);
-		if (cl)
-			closure_put(cl);
+	btree_bounce_free(c,
+		wbio->order,
+		wbio->used_mempool,
+		wbio->data);
+
+	if (wbio->replicas_failed) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&c->btree_write_error_lock, flags);
+		bio_list_add(&c->read_retry_list, &wbio->bio);
+		spin_unlock_irqrestore(&c->btree_write_error_lock, flags);
+		queue_work(c->wq, &c->btree_write_error_work);
+		return;
 	}
+
+	bio_put(bio);
+	btree_node_write_done(c, b);
+	if (cl)
+		closure_put(cl);
 }
 
 static int validate_bset_for_write(struct bch_fs *c, struct btree *b,
@@ -1411,7 +1461,6 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 			    struct closure *parent,
 			    enum six_lock_type lock_type_held)
 {
-	struct bio *bio;
 	struct bch_write_bio *wbio;
 	struct bset_tree *t;
 	struct bset *i;
@@ -1458,7 +1507,7 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 	} while (cmpxchg_acquire(&b->flags, old, new) != old);
 
 	BUG_ON(!list_empty(&b->write_blocked));
-	BUG_ON(!list_empty_careful(&b->reachable) != !b->written);
+	BUG_ON((b->will_make_reachable != NULL) != !b->written);
 
 	BUG_ON(b->written >= c->sb.btree_node_size);
 	BUG_ON(bset_written(b, btree_bset_last(b)));
@@ -1601,23 +1650,20 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 
 	trace_btree_write(b, bytes_to_write, sectors_to_write);
 
-	bio = bio_alloc_bioset(GFP_NOIO, 1 << order, &c->bio_write);
-
-	wbio			= to_wbio(bio);
+	wbio = wbio_init(bio_alloc_bioset(GFP_NOIO, 1 << order, &c->bio_write));
 	wbio->cl		= parent;
-	wbio->bounce		= true;
-	wbio->put_bio		= true;
 	wbio->order		= order;
 	wbio->used_mempool	= used_mempool;
-	bio->bi_opf		= REQ_OP_WRITE|REQ_META|REQ_FUA;
-	bio->bi_iter.bi_size	= sectors_to_write << 9;
-	bio->bi_end_io		= btree_node_write_endio;
-	bio->bi_private		= b;
+	wbio->data		= data;
+	wbio->bio.bi_opf	= REQ_OP_WRITE|REQ_META|REQ_FUA;
+	wbio->bio.bi_iter.bi_size = sectors_to_write << 9;
+	wbio->bio.bi_end_io	= btree_node_write_endio;
+	wbio->bio.bi_private	= b;
 
 	if (parent)
 		closure_get(parent);
 
-	bch2_bio_map(bio, data);
+	bch2_bio_map(&wbio->bio, data);
 
 	/*
 	 * If we're appending to a leaf node, we don't technically need FUA -
diff --git a/libbcachefs/btree_io.h b/libbcachefs/btree_io.h
index 7333f30..91263ee 100644
--- a/libbcachefs/btree_io.h
+++ b/libbcachefs/btree_io.h
@@ -37,7 +37,7 @@ static inline void btree_node_wait_on_io(struct btree *b)
 static inline bool btree_node_may_write(struct btree *b)
 {
 	return list_empty_careful(&b->write_blocked) &&
-		list_empty_careful(&b->reachable);
+		!b->will_make_reachable;
 }
 
 enum compact_mode {
@@ -79,6 +79,7 @@ int bch2_btree_root_read(struct bch_fs *, enum btree_id,
 
 void bch2_btree_complete_write(struct bch_fs *, struct btree *,
 			      struct btree_write *);
+void bch2_btree_write_error_work(struct work_struct *);
 
 void __bch2_btree_node_write(struct bch_fs *, struct btree *,
 			    struct closure *, enum six_lock_type);
diff --git a/libbcachefs/btree_iter.c b/libbcachefs/btree_iter.c
index ecad24f..46df99f 100644
--- a/libbcachefs/btree_iter.c
+++ b/libbcachefs/btree_iter.c
@@ -252,6 +252,8 @@ static int __bch2_btree_iter_unlock(struct btree_iter *iter)
 	while (iter->nodes_locked)
 		btree_node_unlock(iter, __ffs(iter->nodes_locked));
 
+	iter->flags &= ~BTREE_ITER_UPTODATE;
+
 	return iter->flags & BTREE_ITER_ERROR ? -EIO : 0;
 }
 
@@ -1006,16 +1008,30 @@ void bch2_btree_iter_set_pos_same_leaf(struct btree_iter *iter, struct bpos new_
 		iter->flags |= BTREE_ITER_AT_END_OF_LEAF;
 
 	iter->pos = new_pos;
+	iter->flags &= ~BTREE_ITER_UPTODATE;
 }
 
 void bch2_btree_iter_set_pos(struct btree_iter *iter, struct bpos new_pos)
 {
 	EBUG_ON(bkey_cmp(new_pos, iter->pos) < 0); /* XXX handle this */
 	iter->pos = new_pos;
+	iter->flags &= ~BTREE_ITER_UPTODATE;
 }
 
 void bch2_btree_iter_advance_pos(struct btree_iter *iter)
 {
+	if (iter->flags & BTREE_ITER_UPTODATE &&
+	    !(iter->flags & BTREE_ITER_WITH_HOLES)) {
+		struct bkey_s_c k;
+
+		__btree_iter_advance(iter);
+		k = __btree_iter_peek(iter);
+		if (likely(k.k)) {
+			iter->pos = bkey_start_pos(k.k);
+			return;
+		}
+	}
+
 	/*
 	 * We use iter->k instead of iter->pos for extents: iter->pos will be
 	 * equal to the start of the extent we returned, but we need to advance
@@ -1032,6 +1048,7 @@ void bch2_btree_iter_rewind(struct btree_iter *iter, struct bpos pos)
 	BUG_ON(bkey_cmp(pos, iter->nodes[iter->level]->data->min_key) < 0);
 
 	iter->pos = pos;
+	iter->flags &= ~BTREE_ITER_UPTODATE;
 	__btree_iter_init(iter, iter->nodes[iter->level]);
 }
 
@@ -1043,6 +1060,17 @@ struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
 	EBUG_ON(!!(iter->flags & BTREE_ITER_IS_EXTENTS) !=
 		(iter->btree_id == BTREE_ID_EXTENTS));
 
+	if (iter->flags & BTREE_ITER_UPTODATE) {
+		struct btree *b = iter->nodes[0];
+		struct bkey_packed *k =
+			__bch2_btree_node_iter_peek_all(&iter->node_iters[0], b);
+
+		return (struct bkey_s_c) {
+			.k = &iter->k,
+			.v = bkeyp_val(&b->format, k)
+		};
+	}
+
 	while (1) {
 		ret = bch2_btree_iter_traverse(iter);
 		if (unlikely(ret)) {
@@ -1058,7 +1086,9 @@ struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
 			 */
 			if (!(iter->flags & BTREE_ITER_IS_EXTENTS) ||
 			    bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0)
-				bch2_btree_iter_set_pos(iter, bkey_start_pos(k.k));
+				iter->pos = bkey_start_pos(k.k);
+
+			iter->flags |= BTREE_ITER_UPTODATE;
 			return k;
 		}
 
@@ -1083,6 +1113,8 @@ struct bkey_s_c bch2_btree_iter_peek_with_holes(struct btree_iter *iter)
 	EBUG_ON(!!(iter->flags & BTREE_ITER_IS_EXTENTS) !=
 		(iter->btree_id == BTREE_ID_EXTENTS));
 
+	iter->flags &= ~BTREE_ITER_UPTODATE;
+
 	while (1) {
 		ret = bch2_btree_iter_traverse(iter);
 		if (unlikely(ret)) {
@@ -1131,12 +1163,15 @@ void __bch2_btree_iter_init(struct btree_iter *iter, struct bch_fs *c,
 			    unsigned locks_want, unsigned depth,
 			    unsigned flags)
 {
+	EBUG_ON(depth >= BTREE_MAX_DEPTH);
+	EBUG_ON(locks_want > BTREE_MAX_DEPTH);
+
 	iter->c				= c;
 	iter->pos			= pos;
 	iter->flags			= flags;
 	iter->btree_id			= btree_id;
 	iter->level			= depth;
-	iter->locks_want		= min(locks_want, BTREE_MAX_DEPTH);
+	iter->locks_want		= locks_want;
 	iter->nodes_locked		= 0;
 	iter->nodes_intent_locked	= 0;
 	memset(iter->nodes, 0, sizeof(iter->nodes));
diff --git a/libbcachefs/btree_iter.h b/libbcachefs/btree_iter.h
index 57f3876..34e5035 100644
--- a/libbcachefs/btree_iter.h
+++ b/libbcachefs/btree_iter.h
@@ -4,19 +4,20 @@
 #include "btree_types.h"
 
 
-#define BTREE_ITER_INTENT		(1 << 0)
+#define BTREE_ITER_UPTODATE		(1 << 0)
 #define BTREE_ITER_WITH_HOLES		(1 << 1)
-#define BTREE_ITER_PREFETCH		(1 << 2)
+#define BTREE_ITER_INTENT		(1 << 2)
+#define BTREE_ITER_PREFETCH		(1 << 3)
 /*
  * Used in bch2_btree_iter_traverse(), to indicate whether we're searching for
  * @pos or the first key strictly greater than @pos
  */
-#define BTREE_ITER_IS_EXTENTS		(1 << 3)
+#define BTREE_ITER_IS_EXTENTS		(1 << 4)
 /*
  * indicates we need to call bch2_btree_iter_traverse() to revalidate iterator:
  */
-#define BTREE_ITER_AT_END_OF_LEAF	(1 << 4)
-#define BTREE_ITER_ERROR		(1 << 5)
+#define BTREE_ITER_AT_END_OF_LEAF	(1 << 5)
+#define BTREE_ITER_ERROR		(1 << 6)
 
 /*
  * @pos			- iterator's current position
@@ -223,17 +224,23 @@ static inline int btree_iter_cmp(const struct btree_iter *l,
 #define for_each_btree_node(_iter, _c, _btree_id, _start, _flags, _b)	\
 	__for_each_btree_node(_iter, _c, _btree_id, _start, 0, 0, _flags, _b)
 
+static inline struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter,
+						     unsigned flags)
+{
+	return flags & BTREE_ITER_WITH_HOLES
+		? bch2_btree_iter_peek_with_holes(iter)
+		: bch2_btree_iter_peek(iter);
+}
+
 #define for_each_btree_key(_iter, _c, _btree_id,  _start, _flags, _k)	\
-	for (bch2_btree_iter_init((_iter), (_c), (_btree_id),	\
-				  (_start), (_flags));		\
-	     !IS_ERR_OR_NULL(((_k) = (((_flags) & BTREE_ITER_WITH_HOLES)\
-				? bch2_btree_iter_peek_with_holes(_iter)\
-				: bch2_btree_iter_peek(_iter))).k);	\
+	for (bch2_btree_iter_init((_iter), (_c), (_btree_id),		\
+				  (_start), (_flags));			\
+	     !IS_ERR_OR_NULL(((_k) = __bch2_btree_iter_peek(_iter, _flags)).k);\
 	     bch2_btree_iter_advance_pos(_iter))
 
 static inline int btree_iter_err(struct bkey_s_c k)
 {
-	return IS_ERR(k.k) ? PTR_ERR(k.k) : 0;
+	return PTR_ERR_OR_ZERO(k.k);
 }
 
 /*
diff --git a/libbcachefs/btree_types.h b/libbcachefs/btree_types.h
index c613a7b..7085feb 100644
--- a/libbcachefs/btree_types.h
+++ b/libbcachefs/btree_types.h
@@ -116,7 +116,7 @@ struct btree {
 	 * another write - because that write also won't yet be reachable and
 	 * marking it as completed before it's reachable would be incorrect:
 	 */
-	struct list_head	reachable;
+	struct btree_interior_update *will_make_reachable;
 
 	struct open_bucket	*ob;
 
@@ -143,7 +143,6 @@ static inline void clear_btree_node_ ## flag(struct btree *b)		\
 enum btree_flags {
 	BTREE_NODE_read_in_flight,
 	BTREE_NODE_read_error,
-	BTREE_NODE_write_error,
 	BTREE_NODE_dirty,
 	BTREE_NODE_need_write,
 	BTREE_NODE_noevict,
@@ -155,7 +154,6 @@ enum btree_flags {
 
 BTREE_FLAG(read_in_flight);
 BTREE_FLAG(read_error);
-BTREE_FLAG(write_error);
 BTREE_FLAG(dirty);
 BTREE_FLAG(need_write);
 BTREE_FLAG(noevict);
diff --git a/libbcachefs/btree_update.c b/libbcachefs/btree_update.c
index 9794ac3..c7b2018 100644
--- a/libbcachefs/btree_update.c
+++ b/libbcachefs/btree_update.c
@@ -21,6 +21,11 @@
 static void btree_interior_update_updated_root(struct bch_fs *,
 					       struct btree_interior_update *,
 					       enum btree_id);
+static void btree_interior_update_will_make_reachable(struct bch_fs *,
+				struct btree_interior_update *,
+				struct btree *);
+static void btree_interior_update_drop_new_node(struct bch_fs *,
+						struct btree *);
 
 /* Calculate ideal packed bkey format for new btree nodes: */
 
@@ -166,7 +171,7 @@ static void __btree_node_free(struct bch_fs *c, struct btree *b,
 	BUG_ON(b == btree_node_root(c, b));
 	BUG_ON(b->ob);
 	BUG_ON(!list_empty(&b->write_blocked));
-	BUG_ON(!list_empty(&b->reachable));
+	BUG_ON(b->will_make_reachable);
 
 	clear_btree_node_noevict(b);
 
@@ -191,6 +196,8 @@ void bch2_btree_node_free_never_inserted(struct bch_fs *c, struct btree *b)
 {
 	struct open_bucket *ob = b->ob;
 
+	btree_interior_update_drop_new_node(c, b);
+
 	b->ob = NULL;
 
 	clear_btree_node_dirty(b);
@@ -299,6 +306,7 @@ mem_alloc:
 
 static struct btree *bch2_btree_node_alloc(struct bch_fs *c,
 					  unsigned level, enum btree_id id,
+					  struct btree_interior_update *as,
 					  struct btree_reserve *reserve)
 {
 	struct btree *b;
@@ -322,7 +330,7 @@ static struct btree *bch2_btree_node_alloc(struct bch_fs *c,
 
 	bch2_btree_build_aux_trees(b);
 
-	bch2_check_mark_super(c, bkey_i_to_s_c_extent(&b->key), BCH_DATA_BTREE);
+	btree_interior_update_will_make_reachable(c, as, b);
 
 	trace_btree_node_alloc(c, b);
 	return b;
@@ -331,11 +339,12 @@ static struct btree *bch2_btree_node_alloc(struct bch_fs *c,
 struct btree *__bch2_btree_node_alloc_replacement(struct bch_fs *c,
 						  struct btree *b,
 						  struct bkey_format format,
+						  struct btree_interior_update *as,
 						  struct btree_reserve *reserve)
 {
 	struct btree *n;
 
-	n = bch2_btree_node_alloc(c, b->level, b->btree_id, reserve);
+	n = bch2_btree_node_alloc(c, b->level, b->btree_id, as, reserve);
 
 	n->data->min_key	= b->data->min_key;
 	n->data->max_key	= b->data->max_key;
@@ -353,6 +362,7 @@ struct btree *__bch2_btree_node_alloc_replacement(struct bch_fs *c,
 
 static struct btree *bch2_btree_node_alloc_replacement(struct bch_fs *c,
 						struct btree *b,
+						struct btree_interior_update *as,
 						struct btree_reserve *reserve)
 {
 	struct bkey_format new_f = bch2_btree_calc_format(b);
@@ -364,7 +374,7 @@ static struct btree *bch2_btree_node_alloc_replacement(struct bch_fs *c,
 	if (!bch2_btree_node_format_fits(c, b, &new_f))
 		new_f = b->format;
 
-	return __bch2_btree_node_alloc_replacement(c, b, new_f, reserve);
+	return __bch2_btree_node_alloc_replacement(c, b, new_f, as, reserve);
 }
 
 static void bch2_btree_set_root_inmem(struct bch_fs *c, struct btree *b,
@@ -478,9 +488,10 @@ static void bch2_btree_set_root(struct btree_iter *iter, struct btree *b,
 
 static struct btree *__btree_root_alloc(struct bch_fs *c, unsigned level,
 					enum btree_id id,
+					struct btree_interior_update *as,
 					struct btree_reserve *reserve)
 {
-	struct btree *b = bch2_btree_node_alloc(c, level, id, reserve);
+	struct btree *b = bch2_btree_node_alloc(c, level, id, as, reserve);
 
 	b->data->min_key = POS_MIN;
 	b->data->max_key = POS_MAX;
@@ -581,6 +592,11 @@ static struct btree_reserve *__bch2_btree_reserve_get(struct bch_fs *c,
 			goto err_free;
 		}
 
+		ret = bch2_check_mark_super(c, bkey_i_to_s_c_extent(&b->key),
+					    BCH_DATA_BTREE);
+		if (ret)
+			goto err_free;
+
 		reserve->b[reserve->nr++] = b;
 	}
 
@@ -608,11 +624,12 @@ struct btree_reserve *bch2_btree_reserve_get(struct bch_fs *c,
 int bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id,
 			 struct closure *writes)
 {
-	struct closure cl;
+	struct btree_interior_update as;
 	struct btree_reserve *reserve;
+	struct closure cl;
 	struct btree *b;
-	LIST_HEAD(reachable_list);
 
+	memset(&as, 0, sizeof(as));
 	closure_init_stack(&cl);
 
 	while (1) {
@@ -627,15 +644,14 @@ int bch2_btree_root_alloc(struct bch_fs *c, enum btree_id id,
 		closure_sync(&cl);
 	}
 
-	b = __btree_root_alloc(c, 0, id, reserve);
-	list_add(&b->reachable, &reachable_list);
+	b = __btree_root_alloc(c, 0, id, &as, reserve);
 
 	bch2_btree_node_write(c, b, writes, SIX_LOCK_intent);
 
 	bch2_btree_set_root_initial(c, b, reserve);
-	bch2_btree_open_bucket_put(c, b);
 
-	list_del_init(&b->reachable);
+	btree_interior_update_drop_new_node(c, b);
+	bch2_btree_open_bucket_put(c, b);
 	six_unlock_intent(&b->lock);
 
 	bch2_btree_reserve_put(c, reserve);
@@ -819,9 +835,12 @@ void bch2_btree_journal_key(struct btree_insert *trans,
 		/* ick */
 		insert->k.needs_whiteout = false;
 		bch2_journal_add_keys(j, &trans->journal_res,
-				     b->btree_id, insert);
+				      b->btree_id, insert);
 		insert->k.needs_whiteout = needs_whiteout;
 
+		bch2_journal_set_has_inode(j, &trans->journal_res,
+					   insert->k.p.inode);
+
 		if (trans->journal_seq)
 			*trans->journal_seq = seq;
 		btree_bset_last(b)->journal_seq = cpu_to_le64(seq);
@@ -891,7 +910,6 @@ bch2_btree_interior_update_alloc(struct bch_fs *c)
 	as->c		= c;
 	as->mode	= BTREE_INTERIOR_NO_UPDATE;
 	INIT_LIST_HEAD(&as->write_blocked_list);
-	INIT_LIST_HEAD(&as->reachable_list);
 
 	bch2_keylist_init(&as->parent_keys, as->inline_keys,
 			 ARRAY_SIZE(as->inline_keys));
@@ -916,16 +934,16 @@ static void btree_interior_update_nodes_reachable(struct closure *cl)
 	struct btree_interior_update *as =
 		container_of(cl, struct btree_interior_update, cl);
 	struct bch_fs *c = as->c;
-	unsigned i;
 
 	bch2_journal_pin_drop(&c->journal, &as->journal);
 
 	mutex_lock(&c->btree_interior_update_lock);
 
-	while (!list_empty(&as->reachable_list)) {
-		struct btree *b = list_first_entry(&as->reachable_list,
-						   struct btree, reachable);
-		list_del_init(&b->reachable);
+	while (as->nr_new_nodes) {
+		struct btree *b = as->new_nodes[--as->nr_new_nodes];
+
+		BUG_ON(b->will_make_reachable != as);
+		b->will_make_reachable = NULL;
 		mutex_unlock(&c->btree_interior_update_lock);
 
 		six_lock_read(&b->lock);
@@ -934,9 +952,8 @@ static void btree_interior_update_nodes_reachable(struct closure *cl)
 		mutex_lock(&c->btree_interior_update_lock);
 	}
 
-	for (i = 0; i < as->nr_pending; i++)
-		bch2_btree_node_free_ondisk(c, &as->pending[i]);
-	as->nr_pending = 0;
+	while (as->nr_pending)
+		bch2_btree_node_free_ondisk(c, &as->pending[--as->nr_pending]);
 
 	list_del(&as->list);
 	mutex_unlock(&c->btree_interior_update_lock);
@@ -1185,6 +1202,68 @@ static void btree_interior_update_updated_root(struct bch_fs *c,
 		    system_freezable_wq);
 }
 
+static void btree_interior_update_will_make_reachable(struct bch_fs *c,
+				struct btree_interior_update *as,
+				struct btree *b)
+{
+	mutex_lock(&c->btree_interior_update_lock);
+	BUG_ON(as->nr_new_nodes >= ARRAY_SIZE(as->new_nodes));
+	BUG_ON(b->will_make_reachable);
+
+	as->new_nodes[as->nr_new_nodes++] = b;
+	b->will_make_reachable = as;
+	mutex_unlock(&c->btree_interior_update_lock);
+}
+
+static void __btree_interior_update_drop_new_node(struct btree *b)
+{
+	struct btree_interior_update *as = b->will_make_reachable;
+	unsigned i;
+
+	BUG_ON(!as);
+
+	for (i = 0; i < as->nr_new_nodes; i++)
+		if (as->new_nodes[i] == b)
+			goto found;
+
+	BUG();
+found:
+	as->nr_new_nodes--;
+	memmove(&as->new_nodes[i],
+		&as->new_nodes[i + 1],
+		sizeof(struct btree *) * (as->nr_new_nodes - i));
+	b->will_make_reachable = NULL;
+}
+
+static void btree_interior_update_drop_new_node(struct bch_fs *c,
+						struct btree *b)
+{
+	mutex_lock(&c->btree_interior_update_lock);
+	__btree_interior_update_drop_new_node(b);
+	mutex_unlock(&c->btree_interior_update_lock);
+}
+
+static void bch2_btree_interior_update_add_node_reference(struct bch_fs *c,
+						   struct btree_interior_update *as,
+						   struct btree *b)
+{
+	struct pending_btree_node_free *d;
+
+	mutex_lock(&c->btree_interior_update_lock);
+
+	/* Add this node to the list of nodes being freed: */
+	BUG_ON(as->nr_pending >= ARRAY_SIZE(as->pending));
+
+	d = &as->pending[as->nr_pending++];
+	d->index_update_done	= false;
+	d->seq			= b->data->keys.seq;
+	d->btree_id		= b->btree_id;
+	d->level		= b->level;
+	bkey_copy(&d->key, &b->key);
+
+	mutex_unlock(&c->btree_interior_update_lock);
+}
+
 /*
  * @b is being split/rewritten: it may have pointers to not-yet-written btree
  * nodes and thus outstanding btree_interior_updates - redirect @b's
@@ -1196,10 +1275,11 @@ void bch2_btree_interior_update_will_free_node(struct bch_fs *c,
 {
 	struct closure *cl, *cl_n;
 	struct btree_interior_update *p, *n;
-	struct pending_btree_node_free *d;
 	struct btree_write *w;
 	struct bset_tree *t;
 
+	bch2_btree_interior_update_add_node_reference(c, as, b);
+
 	/*
 	 * Does this node have data that hasn't been written in the journal?
 	 *
@@ -1213,16 +1293,6 @@ void bch2_btree_interior_update_will_free_node(struct bch_fs *c,
 
 	mutex_lock(&c->btree_interior_update_lock);
 
-	/* Add this node to the list of nodes being freed: */
-	BUG_ON(as->nr_pending >= ARRAY_SIZE(as->pending));
-
-	d = &as->pending[as->nr_pending++];
-	d->index_update_done	= false;
-	d->seq			= b->data->keys.seq;
-	d->btree_id		= b->btree_id;
-	d->level		= b->level;
-	bkey_copy(&d->key, &b->key);
-
 	/*
 	 * Does this node have any btree_interior_update operations preventing
 	 * it from being written?
@@ -1255,8 +1325,13 @@ void bch2_btree_interior_update_will_free_node(struct bch_fs *c,
 				      &as->journal, interior_update_flush);
 	bch2_journal_pin_drop(&c->journal, &w->journal);
 
-	if (!list_empty(&b->reachable))
-		list_del_init(&b->reachable);
+	w = btree_prev_write(b);
+	bch2_journal_pin_add_if_older(&c->journal, &w->journal,
+				      &as->journal, interior_update_flush);
+	bch2_journal_pin_drop(&c->journal, &w->journal);
+
+	if (b->will_make_reachable)
+		__btree_interior_update_drop_new_node(b);
 
 	mutex_unlock(&c->btree_interior_update_lock);
 }
@@ -1301,7 +1376,7 @@ err:
 #endif
 }
 
-static enum btree_insert_ret
+static int
 bch2_btree_insert_keys_interior(struct btree *b,
 			       struct btree_iter *iter,
 			       struct keylist *insert_keys,
@@ -1324,7 +1399,7 @@ bch2_btree_insert_keys_interior(struct btree *b,
 	if (bch_keylist_u64s(insert_keys) >
 	    bch_btree_keys_u64s_remaining(c, b)) {
 		bch2_btree_node_unlock_write(b, iter);
-		return BTREE_INSERT_BTREE_NODE_FULL;
+		return -1;
 	}
 
 	/* Don't screw up @iter's position: */
@@ -1362,7 +1437,7 @@ bch2_btree_insert_keys_interior(struct btree *b,
 	bch2_btree_node_unlock_write(b, iter);
 
 	btree_node_interior_verify(b);
-	return BTREE_INSERT_OK;
+	return 0;
 }
 
 /*
@@ -1373,13 +1448,13 @@ static struct btree *__btree_split_node(struct btree_iter *iter, struct btree *n
 					struct btree_reserve *reserve,
 					struct btree_interior_update *as)
 {
+	struct bch_fs *c = iter->c;
 	size_t nr_packed = 0, nr_unpacked = 0;
 	struct btree *n2;
 	struct bset *set1, *set2;
 	struct bkey_packed *k, *prev = NULL;
 
-	n2 = bch2_btree_node_alloc(iter->c, n1->level, iter->btree_id, reserve);
-	list_add(&n2->reachable, &as->reachable_list);
+	n2 = bch2_btree_node_alloc(c, n1->level, iter->btree_id, as, reserve);
 
 	n2->data->max_key	= n1->data->max_key;
 	n2->data->format	= n1->format;
@@ -1528,8 +1603,7 @@ static void btree_split(struct btree *b, struct btree_iter *iter,
 
 	bch2_btree_interior_update_will_free_node(c, as, b);
 
-	n1 = bch2_btree_node_alloc_replacement(c, b, reserve);
-	list_add(&n1->reachable, &as->reachable_list);
+	n1 = bch2_btree_node_alloc_replacement(c, b, as, reserve);
 
 	if (b->level)
 		btree_split_insert_keys(iter, n1, insert_keys, reserve);
@@ -1558,8 +1632,7 @@ static void btree_split(struct btree *b, struct btree_iter *iter,
 			/* Depth increases, make a new root */
 			n3 = __btree_root_alloc(c, b->level + 1,
 						iter->btree_id,
-						reserve);
-			list_add(&n3->reachable, &as->reachable_list);
+						as, reserve);
 
 			n3->sib_u64s[0] = U16_MAX;
 			n3->sib_u64s[1] = U16_MAX;
@@ -1641,16 +1714,10 @@ void bch2_btree_insert_node(struct btree *b,
 	BUG_ON(!b->level);
 	BUG_ON(!reserve || !as);
 
-	switch (bch2_btree_insert_keys_interior(b, iter, insert_keys,
-					       as, reserve)) {
-	case BTREE_INSERT_OK:
-		break;
-	case BTREE_INSERT_BTREE_NODE_FULL:
+	if ((as->flags & BTREE_INTERIOR_UPDATE_MUST_REWRITE) ||
+	    bch2_btree_insert_keys_interior(b, iter, insert_keys,
+					    as, reserve))
 		btree_split(b, iter, insert_keys, reserve, as);
-		break;
-	default:
-		BUG();
-	}
 }
 
 static int bch2_btree_split_leaf(struct btree_iter *iter, unsigned flags)
@@ -1859,8 +1926,7 @@ retry:
 	bch2_btree_interior_update_will_free_node(c, as, b);
 	bch2_btree_interior_update_will_free_node(c, as, m);
 
-	n = bch2_btree_node_alloc(c, b->level, b->btree_id, reserve);
-	list_add(&n->reachable, &as->reachable_list);
+	n = bch2_btree_node_alloc(c, b->level, b->btree_id, as, reserve);
 
 	n->data->min_key	= prev->data->min_key;
 	n->data->max_key	= next->data->max_key;
@@ -1945,6 +2011,8 @@ btree_insert_key(struct btree_insert *trans,
 	int old_live_u64s = b->nr.live_u64s;
 	int live_u64s_added, u64s_added;
 
+	iter->flags &= ~BTREE_ITER_UPTODATE;
+
 	ret = !btree_node_is_extents(b)
 		? bch2_insert_fixup_key(trans, insert)
 		: bch2_insert_fixup_extent(trans, insert);
@@ -2383,8 +2451,7 @@ static int __btree_node_rewrite(struct bch_fs *c, struct btree_iter *iter,
 
 	bch2_btree_interior_update_will_free_node(c, as, b);
 
-	n = bch2_btree_node_alloc_replacement(c, b, reserve);
-	list_add(&n->reachable, &as->reachable_list);
+	n = bch2_btree_node_alloc_replacement(c, b, as, reserve);
 
 	bch2_btree_build_aux_trees(n);
 	six_unlock_write(&n->lock);
@@ -2464,3 +2531,140 @@ int bch2_btree_node_rewrite(struct bch_fs *c, struct btree_iter *iter,
 	closure_sync(&cl);
 	return ret;
 }
+
+int bch2_btree_node_update_key(struct bch_fs *c, struct btree *b,
+			       struct bkey_i_extent *new_key)
+{
+	struct btree_interior_update *as;
+	struct btree_reserve *reserve = NULL;
+	struct btree *parent, *new_hash = NULL;
+	struct btree_iter iter;
+	struct closure cl;
+	bool must_rewrite_parent = false;
+	int ret;
+
+	__bch2_btree_iter_init(&iter, c, b->btree_id, b->key.k.p,
+			       BTREE_MAX_DEPTH,
+			       b->level, 0);
+	closure_init_stack(&cl);
+
+	if (PTR_HASH(&new_key->k_i) != PTR_HASH(&b->key)) {
+		/* bch2_btree_reserve_get will unlock */
+		do {
+			ret = bch2_btree_node_cannibalize_lock(c, &cl);
+			closure_sync(&cl);
+		} while (ret == -EAGAIN);
+
+		BUG_ON(ret);
+
+		new_hash = bch2_btree_node_mem_alloc(c);
+	}
+retry:
+	reserve = bch2_btree_reserve_get(c, b, 0,
+				BTREE_INSERT_NOFAIL|
+				BTREE_INSERT_USE_RESERVE|
+				BTREE_INSERT_USE_ALLOC_RESERVE,
+				&cl);
+	closure_sync(&cl);
+	if (IS_ERR(reserve)) {
+		ret = PTR_ERR(reserve);
+		if (ret == -EAGAIN || ret == -EINTR)
+			goto retry;
+		goto err;
+	}
+
+	down_read(&c->gc_lock);
+
+	ret = bch2_btree_iter_traverse(&iter);
+	if (ret)
+		goto err;
+
+	mutex_lock(&c->btree_interior_update_lock);
+
+	/*
+	 * Two corner cases that need to be thought about here:
+	 *
+	 * @b may not be reachable yet - there might be another interior update
+	 * operation waiting on @b to be written, and we're gonna deliver the
+	 * write completion to that interior update operation _before_
+	 * persisting the new_key update
+	 *
+	 * That ends up working without us having to do anything special here:
+	 * the reason is, we do kick off (and do the in memory updates) for the
+	 * update for @new_key before we return, creating a new interior_update
+	 * operation here.
+	 *
+	 * The new interior update operation here will in effect override the
+	 * previous one. The previous one was going to terminate - make @b
+	 * reachable - in one of two ways:
+	 * - updating the btree root pointer
+	 *   In that case,
+	 *   no, this doesn't work. argh.
+	 */
+
+	if (b->will_make_reachable)
+		must_rewrite_parent = true;
+
+	/* other case: btree node being freed */
+	if (iter.nodes[b->level] != b) {
+		/* node has been freed: */
+		BUG_ON(btree_node_hashed(b));
+		mutex_unlock(&c->btree_interior_update_lock);
+		goto err;
+	}
+
+	mutex_unlock(&c->btree_interior_update_lock);
+
+	ret = bch2_check_mark_super(c, extent_i_to_s_c(new_key), BCH_DATA_BTREE);
+	if (ret)
+		goto err;
+
+	as = bch2_btree_interior_update_alloc(c);
+
+	if (must_rewrite_parent)
+		as->flags |= BTREE_INTERIOR_UPDATE_MUST_REWRITE;
+
+	bch2_btree_interior_update_add_node_reference(c, as, b);
+
+	if (new_hash) {
+		bkey_copy(&new_hash->key, &new_key->k_i);
+		BUG_ON(bch2_btree_node_hash_insert(c, new_hash,
+					b->level, b->btree_id));
+	}
+
+	parent = iter.nodes[b->level + 1];
+	if (parent) {
+		bch2_btree_insert_node(parent, &iter,
+				       &keylist_single(&b->key),
+				       reserve, as);
+	} else {
+		bch2_btree_set_root(&iter, b, as, reserve);
+	}
+
+	if (new_hash) {
+		mutex_lock(&c->btree_cache_lock);
+		bch2_btree_node_hash_remove(c, b);
+
+		bkey_copy(&b->key, &new_key->k_i);
+		__bch2_btree_node_hash_insert(c, b);
+
+		bch2_btree_node_hash_remove(c, new_hash);
+		mutex_unlock(&c->btree_cache_lock);
+	} else {
+		bkey_copy(&b->key, &new_key->k_i);
+	}
+err:
+	if (!IS_ERR_OR_NULL(reserve))
+		bch2_btree_reserve_put(c, reserve);
+	if (new_hash) {
+		mutex_lock(&c->btree_cache_lock);
+		list_move(&b->list, &c->btree_cache_freeable);
+		mutex_unlock(&c->btree_cache_lock);
+
+		six_unlock_write(&new_hash->lock);
+		six_unlock_intent(&new_hash->lock);
+	}
+	bch2_btree_iter_unlock(&iter);
+	up_read(&c->gc_lock);
+	return ret;
+}
diff --git a/libbcachefs/btree_update.h b/libbcachefs/btree_update.h
index b5cfa89..086077f 100644
--- a/libbcachefs/btree_update.h
+++ b/libbcachefs/btree_update.h
@@ -76,6 +76,9 @@ struct btree_interior_update {
 		BTREE_INTERIOR_UPDATING_AS,
 	} mode;
 
+	unsigned			flags;
+	struct btree_reserve		*reserve;
+
 	/*
 	 * BTREE_INTERIOR_UPDATING_NODE:
 	 * The update that made the new nodes visible was a regular update to an
@@ -86,7 +89,6 @@ struct btree_interior_update {
 	 */
 	struct btree			*b;
 	struct list_head		write_blocked_list;
-	struct list_head		reachable_list;
 
 	/*
 	 * BTREE_INTERIOR_UPDATING_AS: btree node we updated was freed, so now
@@ -117,6 +119,10 @@ struct btree_interior_update {
 	struct pending_btree_node_free	pending[BTREE_MAX_DEPTH + GC_MERGE_NODES];
 	unsigned			nr_pending;
 
+	/* New nodes, that will be made reachable by this update: */
+	struct btree			*new_nodes[BTREE_MAX_DEPTH * 2 + GC_MERGE_NODES];
+	unsigned			nr_new_nodes;
+
 	/* Only here to reduce stack usage on recursive splits: */
 	struct keylist			parent_keys;
 	/*
@@ -127,6 +133,8 @@ struct btree_interior_update {
 	u64				inline_keys[BKEY_BTREE_PTR_U64s_MAX * 3];
 };
 
+#define BTREE_INTERIOR_UPDATE_MUST_REWRITE	(1 << 0)
+
 #define for_each_pending_btree_node_free(c, as, p)			\
 	list_for_each_entry(as, &c->btree_interior_update_list, list)	\
 		for (p = as->pending; p < as->pending + as->nr_pending; p++)
@@ -138,6 +146,7 @@ void bch2_btree_open_bucket_put(struct bch_fs *c, struct btree *);
 struct btree *__bch2_btree_node_alloc_replacement(struct bch_fs *,
 					     struct btree *,
 					     struct bkey_format,
+					     struct btree_interior_update *,
 					     struct btree_reserve *);
 
 struct btree_interior_update *
@@ -426,6 +435,8 @@ int bch2_btree_delete_range(struct bch_fs *, enum btree_id,
 
 int bch2_btree_node_rewrite(struct bch_fs *c, struct btree_iter *,
 			    __le64, unsigned);
+int bch2_btree_node_update_key(struct bch_fs *, struct btree *,
+			       struct bkey_i_extent *);
 
 #endif /* _BCACHE_BTREE_INSERT_H */
 
diff --git a/libbcachefs/extents.c b/libbcachefs/extents.c
index 74d54ab..1b0e3da 100644
--- a/libbcachefs/extents.c
+++ b/libbcachefs/extents.c
@@ -153,6 +153,37 @@ unsigned bch2_extent_nr_dirty_ptrs(struct bkey_s_c k)
 	return nr_ptrs;
 }
 
+/* Doesn't cleanup redundant crcs */
+void __bch2_extent_drop_ptr(struct bkey_s_extent e, struct bch_extent_ptr *ptr)
+{
+	EBUG_ON(ptr < &e.v->start->ptr ||
+		ptr >= &extent_entry_last(e)->ptr);
+	EBUG_ON(ptr->type != 1 << BCH_EXTENT_ENTRY_ptr);
+	memmove_u64s_down(ptr, ptr + 1,
+			  (u64 *) extent_entry_last(e) - (u64 *) (ptr + 1));
+	e.k->u64s -= sizeof(*ptr) / sizeof(u64);
+}
+
+void bch2_extent_drop_ptr(struct bkey_s_extent e, struct bch_extent_ptr *ptr)
+{
+	__bch2_extent_drop_ptr(e, ptr);
+	bch2_extent_drop_redundant_crcs(e);
+}
+
+void bch2_extent_drop_ptr_idx(struct bkey_s_extent e, unsigned idx)
+{
+	struct bch_extent_ptr *ptr;
+	unsigned i = 0;
+
+	extent_for_each_ptr(e, ptr)
+		if (i++ == idx)
+			goto found;
+
+	BUG();
+found:
+	bch2_extent_drop_ptr(e, ptr);
+}
+
 /* returns true if equal */
 static bool crc_cmp(union bch_extent_crc *l, union bch_extent_crc *r)
 {
diff --git a/libbcachefs/extents.h b/libbcachefs/extents.h
index 3a95248..3dc06cb 100644
--- a/libbcachefs/extents.h
+++ b/libbcachefs/extents.h
@@ -552,24 +552,9 @@ static inline unsigned extent_current_nonce(struct bkey_s_c_extent e)
 void bch2_extent_narrow_crcs(struct bkey_s_extent);
 void bch2_extent_drop_redundant_crcs(struct bkey_s_extent);
 
-/* Doesn't cleanup redundant crcs */
-static inline void __bch2_extent_drop_ptr(struct bkey_s_extent e,
-					 struct bch_extent_ptr *ptr)
-{
-	EBUG_ON(ptr < &e.v->start->ptr ||
-		ptr >= &extent_entry_last(e)->ptr);
-	EBUG_ON(ptr->type != 1 << BCH_EXTENT_ENTRY_ptr);
-	memmove_u64s_down(ptr, ptr + 1,
-			  (u64 *) extent_entry_last(e) - (u64 *) (ptr + 1));
-	e.k->u64s -= sizeof(*ptr) / sizeof(u64);
-}
-
-static inline void bch2_extent_drop_ptr(struct bkey_s_extent e,
-				       struct bch_extent_ptr *ptr)
-{
-	__bch2_extent_drop_ptr(e, ptr);
-	bch2_extent_drop_redundant_crcs(e);
-}
+void __bch2_extent_drop_ptr(struct bkey_s_extent, struct bch_extent_ptr *);
+void bch2_extent_drop_ptr(struct bkey_s_extent, struct bch_extent_ptr *);
+void bch2_extent_drop_ptr_idx(struct bkey_s_extent, unsigned);
 
 const struct bch_extent_ptr *
 bch2_extent_has_device(struct bkey_s_c_extent, unsigned);
diff --git a/libbcachefs/fs-io.c b/libbcachefs/fs-io.c
index 803611d..079f958 100644
--- a/libbcachefs/fs-io.c
+++ b/libbcachefs/fs-io.c
@@ -871,9 +871,8 @@ static void bch2_writepage_io_free(struct closure *cl)
 {
 	struct bch_writepage_io *io = container_of(cl,
 					struct bch_writepage_io, cl);
-	struct bio *bio = &io->bio.bio;
 
-	bio_put(bio);
+	bio_put(&io->op.op.wbio.bio);
 }
 
 static void bch2_writepage_io_done(struct closure *cl)
@@ -881,7 +880,7 @@ static void bch2_writepage_io_done(struct closure *cl)
 	struct bch_writepage_io *io = container_of(cl,
 					struct bch_writepage_io, cl);
 	struct bch_fs *c = io->op.op.c;
-	struct bio *bio = &io->bio.bio;
+	struct bio *bio = &io->op.op.wbio.bio;
 	struct bio_vec *bvec;
 	unsigned i;
 
@@ -940,11 +939,12 @@ static void bch2_writepage_io_done(struct closure *cl)
 static void bch2_writepage_do_io(struct bch_writepage_state *w)
 {
 	struct bch_writepage_io *io = w->io;
+	struct bio *bio = &io->op.op.wbio.bio;
 
 	w->io = NULL;
-	atomic_add(io->bio.bio.bi_vcnt, &io->op.op.c->writeback_pages);
+	atomic_add(bio->bi_vcnt, &io->op.op.c->writeback_pages);
 
-	io->op.op.pos.offset = io->bio.bio.bi_iter.bi_sector;
+	io->op.op.pos.offset = bio->bi_iter.bi_sector;
 
 	closure_call(&io->op.op.cl, bch2_write, NULL, &io->cl);
 	continue_at(&io->cl, bch2_writepage_io_done, NULL);
@@ -970,13 +970,13 @@ alloc_io:
 		w->io = container_of(bio_alloc_bioset(GFP_NOFS,
 						      BIO_MAX_PAGES,
 						      bch2_writepage_bioset),
-				     struct bch_writepage_io, bio.bio);
+				     struct bch_writepage_io, op.op.wbio.bio);
 
 		closure_init(&w->io->cl, NULL);
 		w->io->op.ei		= ei;
 		w->io->op.sectors_added	= 0;
 		w->io->op.is_dio	= false;
-		bch2_write_op_init(&w->io->op.op, c, &w->io->bio,
+		bch2_write_op_init(&w->io->op.op, c,
 				  (struct disk_reservation) {
 					.nr_replicas = c->opts.data_replicas,
 				  },
@@ -987,7 +987,7 @@ alloc_io:
 	}
 
 	if (w->io->op.op.res.nr_replicas != nr_replicas ||
-	    bio_add_page_contig(&w->io->bio.bio, page)) {
+	    bio_add_page_contig(&w->io->op.op.wbio.bio, page)) {
 		bch2_writepage_do_io(w);
 		goto alloc_io;
 	}
@@ -1038,7 +1038,7 @@ do_io:
 	w->io->op.new_i_size = i_size;
 
 	if (wbc->sync_mode == WB_SYNC_ALL)
-		w->io->bio.bio.bi_opf |= REQ_SYNC;
+		w->io->op.op.wbio.bio.bi_opf |= REQ_SYNC;
 
 	/* Before unlocking the page, transfer reservation to w->io: */
 	old = page_state_cmpxchg(page_state(page), new, {
@@ -1110,7 +1110,7 @@ get_pages:
 		done_index = page->index;
 
 		if (w.io &&
-		    !bio_can_add_page_contig(&w.io->bio.bio, page))
+		    !bio_can_add_page_contig(&w.io->op.op.wbio.bio, page))
 			bch2_writepage_do_io(&w);
 
 		if (!w.io &&
@@ -1495,7 +1495,7 @@ static long __bch2_dio_write_complete(struct dio_write *dio)
 	if (dio->iovec && dio->iovec != dio->inline_vecs)
 		kfree(dio->iovec);
 
-	bio_put(&dio->bio.bio);
+	bio_put(&dio->iop.op.wbio.bio);
 	return ret;
 }
 
@@ -1517,11 +1517,11 @@ static void bch2_dio_write_done(struct dio_write *dio)
 	if (dio->iop.op.error)
 		dio->error = dio->iop.op.error;
 
-	bio_for_each_segment_all(bv, &dio->bio.bio, i)
+	bio_for_each_segment_all(bv, &dio->iop.op.wbio.bio, i)
 		put_page(bv->bv_page);
 
 	if (dio->iter.count)
-		bio_reset(&dio->bio.bio);
+		bio_reset(&dio->iop.op.wbio.bio);
 }
 
 static void bch2_do_direct_IO_write(struct dio_write *dio)
@@ -1529,7 +1529,7 @@ static void bch2_do_direct_IO_write(struct dio_write *dio)
 	struct file *file = dio->req->ki_filp;
 	struct inode *inode = file->f_inode;
 	struct bch_inode_info *ei = to_bch_ei(inode);
-	struct bio *bio = &dio->bio.bio;
+	struct bio *bio = &dio->iop.op.wbio.bio;
 	unsigned flags = 0;
 	int ret;
 
@@ -1537,8 +1537,6 @@ static void bch2_do_direct_IO_write(struct dio_write *dio)
 	    !dio->c->opts.journal_flush_disabled)
 		flags |= BCH_WRITE_FLUSH;
 
-	bio->bi_iter.bi_sector = (dio->offset + dio->written) >> 9;
-
 	ret = bio_iov_iter_get_pages(bio, &dio->iter);
 	if (ret < 0) {
 		/*
@@ -1555,10 +1553,9 @@ static void bch2_do_direct_IO_write(struct dio_write *dio)
 	dio->iop.sectors_added	= 0;
 	dio->iop.is_dio		= true;
 	dio->iop.new_i_size	= U64_MAX;
-	bch2_write_op_init(&dio->iop.op, dio->c, &dio->bio,
-			  dio->res,
+	bch2_write_op_init(&dio->iop.op, dio->c, dio->res,
 			  foreground_write_point(dio->c, inode->i_ino),
-			  POS(inode->i_ino, bio->bi_iter.bi_sector),
+			  POS(inode->i_ino, (dio->offset + dio->written) >> 9),
 			  &ei->journal_seq, flags);
 	dio->iop.op.index_update_fn = bchfs_write_index_update;
 
@@ -1619,7 +1616,7 @@ static int bch2_direct_IO_write(struct bch_fs *c, struct kiocb *req,
 	bio = bio_alloc_bioset(GFP_KERNEL,
 			       iov_iter_npages(iter, BIO_MAX_PAGES),
 			       bch2_dio_write_bioset);
-	dio = container_of(bio, struct dio_write, bio.bio);
+	dio = container_of(bio, struct dio_write, iop.op.wbio.bio);
 	dio->req	= req;
 	dio->c		= c;
 	dio->written	= 0;
diff --git a/libbcachefs/fs-io.h b/libbcachefs/fs-io.h
index 3fcc1e7..252a403 100644
--- a/libbcachefs/fs-io.h
+++ b/libbcachefs/fs-io.h
@@ -46,16 +46,16 @@ struct bchfs_write_op {
 	s64			sectors_added;
 	bool			is_dio;
 	u64			new_i_size;
+
+	/* must be last: */
 	struct bch_write_op	op;
 };
 
 struct bch_writepage_io {
 	struct closure		cl;
 
+	/* must be last: */
 	struct bchfs_write_op	op;
-
-	/* must come last: */
-	struct bch_write_bio	bio;
 };
 
 extern struct bio_set *bch2_writepage_bioset;
@@ -76,10 +76,8 @@ struct dio_write {
 
 	struct mm_struct	*mm;
 
-	struct bchfs_write_op	iop;
-
 	/* must be last: */
-	struct bch_write_bio	bio;
+	struct bchfs_write_op	iop;
 };
 
 extern struct bio_set *bch2_dio_write_bioset;
diff --git a/libbcachefs/fs.c b/libbcachefs/fs.c
index 201cdfc..6c9792e 100644
--- a/libbcachefs/fs.c
+++ b/libbcachefs/fs.c
@@ -1458,7 +1458,7 @@ int __init bch2_vfs_init(void)
 		goto err;
 
 	bch2_writepage_bioset =
-		bioset_create(4, offsetof(struct bch_writepage_io, bio.bio));
+		bioset_create(4, offsetof(struct bch_writepage_io, op.op.wbio.bio));
 	if (!bch2_writepage_bioset)
 		goto err;
 
@@ -1466,7 +1466,8 @@ int __init bch2_vfs_init(void)
 	if (!bch2_dio_read_bioset)
 		goto err;
 
-	bch2_dio_write_bioset = bioset_create(4, offsetof(struct dio_write, bio.bio));
+	bch2_dio_write_bioset =
+		bioset_create(4, offsetof(struct dio_write, iop.op.wbio.bio));
 	if (!bch2_dio_write_bioset)
 		goto err;
 
diff --git a/libbcachefs/io.c b/libbcachefs/io.c
index 54b523d..78cdaa3 100644
--- a/libbcachefs/io.c
+++ b/libbcachefs/io.c
@@ -92,12 +92,10 @@ void bch2_submit_wbio_replicas(struct bch_write_bio *wbio, struct bch_fs *c,
 	const struct bch_extent_ptr *ptr;
 	struct bch_write_bio *n;
 	struct bch_dev *ca;
+	unsigned ptr_idx = 0;
 
 	BUG_ON(c->opts.nochanges);
 
-	wbio->split = false;
-	wbio->c = c;
-
 	extent_for_each_ptr(e, ptr) {
 		ca = c->devs[ptr->dev];
 
@@ -107,24 +105,26 @@ void bch2_submit_wbio_replicas(struct bch_write_bio *wbio, struct bch_fs *c,
 
 			n->bio.bi_end_io	= wbio->bio.bi_end_io;
 			n->bio.bi_private	= wbio->bio.bi_private;
-			n->c			= c;
-			n->orig			= &wbio->bio;
-			n->bounce		= false;
+			n->parent		= wbio;
 			n->split		= true;
+			n->bounce		= false;
 			n->put_bio		= true;
 			n->bio.bi_opf		= wbio->bio.bi_opf;
-			__bio_inc_remaining(n->orig);
+			__bio_inc_remaining(&wbio->bio);
 		} else {
 			n = wbio;
+			n->split		= false;
 		}
 
-		if (!journal_flushes_device(ca))
-			n->bio.bi_opf |= REQ_FUA;
-
+		n->c			= c;
 		n->ca			= ca;
+		n->ptr_idx		= ptr_idx++;
 		n->submit_time_us	= local_clock_us();
 		n->bio.bi_iter.bi_sector = ptr->offset;
 
+		if (!journal_flushes_device(ca))
+			n->bio.bi_opf |= REQ_FUA;
+
 		if (likely(percpu_ref_tryget(&ca->io_ref))) {
 			n->have_io_ref		= true;
 			n->bio.bi_bdev		= ca->disk_sb.bdev;
@@ -250,10 +250,9 @@ static void bch2_write_index(struct closure *cl)
 static void bch2_write_discard(struct closure *cl)
 {
 	struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
-	struct bio *bio = &op->bio->bio;
 	struct bpos end = op->pos;
 
-	end.offset += bio_sectors(bio);
+	end.offset += bio_sectors(&op->wbio.bio);
 
 	op->error = bch2_discard(op->c, op->pos, end, op->version,
 				&op->res, NULL, NULL);
@@ -308,31 +307,28 @@ static void bch2_write_io_error(struct closure *cl)
 
 static void bch2_write_endio(struct bio *bio)
 {
-	struct closure *cl = bio->bi_private;
-	struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
-	struct bch_write_bio *wbio = to_wbio(bio);
-	struct bch_fs *c = wbio->c;
-	struct bio *orig = wbio->orig;
-	struct bch_dev *ca = wbio->ca;
+	struct closure *cl		= bio->bi_private;
+	struct bch_write_op *op		= container_of(cl, struct bch_write_op, cl);
+	struct bch_write_bio *wbio	= to_wbio(bio);
+	struct bch_write_bio *parent	= wbio->split ? wbio->parent : NULL;
+	struct bch_fs *c		= wbio->c;
+	struct bch_dev *ca		= wbio->ca;
 
 	if (bch2_dev_nonfatal_io_err_on(bio->bi_error, ca,
-				       "data write"))
+					"data write"))
 		set_closure_fn(cl, bch2_write_io_error, index_update_wq(op));
 
 	if (wbio->have_io_ref)
 		percpu_ref_put(&ca->io_ref);
 
-	if (bio->bi_error && orig)
-		orig->bi_error = bio->bi_error;
-
 	if (wbio->bounce)
 		bch2_bio_free_pages_pool(c, bio);
 
 	if (wbio->put_bio)
 		bio_put(bio);
 
-	if (orig)
-		bio_endio(orig);
+	if (parent)
+		bio_endio(&parent->bio);
 	else
 		closure_put(cl);
 }
@@ -380,11 +376,10 @@ static void init_append_extent(struct bch_write_op *op,
 	bch2_keylist_push(&op->insert_keys);
 }
 
-static int bch2_write_extent(struct bch_write_op *op,
-			    struct open_bucket *ob,
-			    struct bio *orig)
+static int bch2_write_extent(struct bch_write_op *op, struct open_bucket *ob)
 {
 	struct bch_fs *c = op->c;
+	struct bio *orig = &op->wbio.bio;
 	struct bio *bio;
 	struct bch_write_bio *wbio;
 	unsigned key_to_write_offset = op->insert_keys.top_p -
@@ -392,11 +387,13 @@ static int bch2_write_extent(struct bch_write_op *op,
 	struct bkey_i *key_to_write;
 	unsigned csum_type = op->csum_type;
 	unsigned compression_type = op->compression_type;
-	int ret;
+	int ret, more;
 
 	/* don't refetch csum type/compression type */
 	barrier();
 
+	BUG_ON(!bio_sectors(orig));
+
 	/* Need to decompress data? */
 	if ((op->flags & BCH_WRITE_DATA_COMPRESSED) &&
 	    (crc_uncompressed_size(NULL, &op->crc) != op->size ||
@@ -421,11 +418,8 @@ static int bch2_write_extent(struct bch_write_op *op,
 				   ob);
 
 		bio			= orig;
-		wbio			= to_wbio(bio);
-		wbio->orig		= NULL;
-		wbio->bounce		= false;
-		wbio->put_bio		= false;
-		ret			= 0;
+		wbio			= wbio_init(bio);
+		more			= 0;
 	} else if (csum_type != BCH_CSUM_NONE ||
 		   compression_type != BCH_COMPRESSION_NONE) {
 		/* all units here in bytes */
@@ -439,19 +433,18 @@ static int bch2_write_extent(struct bch_write_op *op,
 		bio = bio_alloc_bioset(GFP_NOIO,
 				       DIV_ROUND_UP(output_available, PAGE_SIZE),
 				       &c->bio_write);
+		wbio			= wbio_init(bio);
+		wbio->bounce		= true;
+		wbio->put_bio		= true;
+		/* copy WRITE_SYNC flag */
+		wbio->bio.bi_opf	= orig->bi_opf;
+
 		/*
 		 * XXX: can't use mempool for more than
 		 * BCH_COMPRESSED_EXTENT_MAX worth of pages
 		 */
 		bch2_bio_alloc_pages_pool(c, bio, output_available);
 
-		/* copy WRITE_SYNC flag */
-		bio->bi_opf		= orig->bi_opf;
-		wbio			= to_wbio(bio);
-		wbio->orig		= NULL;
-		wbio->bounce		= true;
-		wbio->put_bio		= true;
-
 		do {
 			unsigned fragment_compression_type = compression_type;
 			size_t dst_len, src_len;
@@ -504,45 +497,43 @@ static int bch2_write_extent(struct bch_write_op *op,
 			mempool_free(bio->bi_io_vec[--bio->bi_vcnt].bv_page,
 				     &c->bio_bounce_pages);
 
-		ret = orig->bi_iter.bi_size != 0;
+		more = orig->bi_iter.bi_size != 0;
 	} else {
 		bio = bio_next_split(orig, ob->sectors_free, GFP_NOIO,
 				     &c->bio_write);
-
-		wbio			= to_wbio(bio);
-		wbio->orig		= NULL;
-		wbio->bounce		= false;
+		wbio			= wbio_init(bio);
 		wbio->put_bio		= bio != orig;
 
 		init_append_extent(op, bio_sectors(bio), bio_sectors(bio),
 				   compression_type, 0,
 				   (struct bch_csum) { 0 }, csum_type, ob);
 
-		ret = bio != orig;
+		more = bio != orig;
 	}
 
+	/* might have done a realloc... */
+
+	key_to_write = (void *) (op->insert_keys.keys_p + key_to_write_offset);
+
+	ret = bch2_check_mark_super(c, bkey_i_to_s_c_extent(key_to_write),
+				    BCH_DATA_USER);
+	if (ret)
+		return ret;
+
 	bio->bi_end_io	= bch2_write_endio;
 	bio->bi_private	= &op->cl;
 	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 
 	closure_get(bio->bi_private);
 
-	/* might have done a realloc... */
-
-	key_to_write = (void *) (op->insert_keys.keys_p + key_to_write_offset);
-
-	bch2_check_mark_super(c, bkey_i_to_s_c_extent(key_to_write),
-			      BCH_DATA_USER);
-
 	bch2_submit_wbio_replicas(to_wbio(bio), c, key_to_write);
-	return ret;
+	return more;
 }
 
 static void __bch2_write(struct closure *cl)
 {
 	struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
 	struct bch_fs *c = op->c;
-	struct bio *bio = &op->bio->bio;
 	unsigned open_bucket_nr = 0;
 	struct open_bucket *b;
 	int ret;
@@ -550,22 +541,12 @@ static void __bch2_write(struct closure *cl)
 	memset(op->open_buckets, 0, sizeof(op->open_buckets));
 
 	if (op->flags & BCH_WRITE_DISCARD) {
-		op->flags |= BCH_WRITE_DONE;
 		bch2_write_discard(cl);
-		bio_put(bio);
+		op->flags |= BCH_WRITE_DONE;
 		continue_at(cl, bch2_write_done, index_update_wq(op));
 	}
 
-	/*
-	 * Journal writes are marked REQ_PREFLUSH; if the original write was a
-	 * flush, it'll wait on the journal write.
-	 */
-	bio->bi_opf &= ~(REQ_PREFLUSH|REQ_FUA);
-
 	do {
-		EBUG_ON(bio->bi_iter.bi_sector != op->pos.offset);
-		EBUG_ON(!bio_sectors(bio));
-
 		if (open_bucket_nr == ARRAY_SIZE(op->open_buckets))
 			continue_at(cl, bch2_write_index, index_update_wq(op));
 
@@ -622,7 +603,7 @@ static void __bch2_write(struct closure *cl)
 		       b - c->open_buckets > U8_MAX);
 		op->open_buckets[open_bucket_nr++] = b - c->open_buckets;
 
-		ret = bch2_write_extent(op, b, bio);
+		ret = bch2_write_extent(op, b);
 
 		bch2_alloc_sectors_done(c, op->wp, b);
 
@@ -703,16 +684,13 @@ void bch2_wake_delayed_writes(unsigned long data)
  * after the data is written it calls bch_journal, and after the keys have been
  * added to the next journal write they're inserted into the btree.
  *
- * It inserts the data in op->bio; bi_sector is used for the key offset, and
- * op->inode is used for the key inode.
- *
  * If op->discard is true, instead of inserting the data it invalidates the
  * region of the cache represented by op->bio and op->inode.
  */
 void bch2_write(struct closure *cl)
 {
 	struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
-	struct bio *bio = &op->bio->bio;
+	struct bio *bio = &op->wbio.bio;
 	struct bch_fs *c = op->c;
 	u64 inode = op->pos.inode;
 
@@ -742,7 +720,7 @@ void bch2_write(struct closure *cl)
 
 		spin_lock_irqsave(&c->foreground_write_pd_lock, flags);
 		bch2_ratelimit_increment(&c->foreground_write_pd.rate,
-					bio->bi_iter.bi_size);
+					 bio->bi_iter.bi_size);
 
 		delay = bch2_ratelimit_delay(&c->foreground_write_pd.rate);
 
@@ -776,15 +754,14 @@ void bch2_write(struct closure *cl)
 }
 
 void bch2_write_op_init(struct bch_write_op *op, struct bch_fs *c,
-		       struct bch_write_bio *bio, struct disk_reservation res,
-		       struct write_point *wp, struct bpos pos,
-		       u64 *journal_seq, unsigned flags)
+			struct disk_reservation res,
+			struct write_point *wp, struct bpos pos,
+			u64 *journal_seq, unsigned flags)
 {
 	EBUG_ON(res.sectors && !res.nr_replicas);
 
 	op->c		= c;
 	op->io_wq	= index_update_wq(op);
-	op->bio		= bio;
 	op->written	= 0;
 	op->error	= 0;
 	op->flags	= flags;
@@ -983,7 +960,7 @@ static void cache_promote_done(struct closure *cl)
 	struct cache_promote_op *op =
 		container_of(cl, struct cache_promote_op, cl);
 
-	bch2_bio_free_pages_pool(op->write.op.c, &op->write.wbio.bio);
+	bch2_bio_free_pages_pool(op->write.op.c, &op->write.op.wbio.bio);
 	kfree(op);
 }
 
@@ -1020,7 +997,7 @@ static void __bch2_read_endio(struct work_struct *work)
 		trace_promote(&rbio->bio);
 
 		/* we now own pages: */
-		swap(promote->write.wbio.bio.bi_vcnt, rbio->bio.bi_vcnt);
+		swap(promote->write.op.wbio.bio.bi_vcnt, rbio->bio.bi_vcnt);
 		rbio->promote = NULL;
 
 		bch2_rbio_done(rbio);
@@ -1112,7 +1089,7 @@ void bch2_read_extent_iter(struct bch_fs *c, struct bch_read_bio *orig,
 		promote_op = kmalloc(sizeof(*promote_op) +
 				sizeof(struct bio_vec) * pages, GFP_NOIO);
 		if (promote_op) {
-			struct bio *promote_bio = &promote_op->write.wbio.bio;
+			struct bio *promote_bio = &promote_op->write.op.wbio.bio;
 
 			bio_init(promote_bio,
 				 promote_bio->bi_inline_vecs,
@@ -1204,7 +1181,7 @@ void bch2_read_extent_iter(struct bch_fs *c, struct bch_read_bio *orig,
 	rbio->bio.bi_end_io	= bch2_read_endio;
 
 	if (promote_op) {
-		struct bio *promote_bio = &promote_op->write.wbio.bio;
+		struct bio *promote_bio = &promote_op->write.op.wbio.bio;
 
 		promote_bio->bi_iter = rbio->bio.bi_iter;
 		memcpy(promote_bio->bi_io_vec, rbio->bio.bi_io_vec,
@@ -1367,12 +1344,11 @@ void bch2_read_retry_work(struct work_struct *work)
 					   read_retry_work);
 	struct bch_read_bio *rbio;
 	struct bio *bio;
-	unsigned long flags;
 
 	while (1) {
-		spin_lock_irqsave(&c->read_retry_lock, flags);
+		spin_lock_irq(&c->read_retry_lock);
 		bio = bio_list_pop(&c->read_retry_list);
-		spin_unlock_irqrestore(&c->read_retry_lock, flags);
+		spin_unlock_irq(&c->read_retry_lock);
 
 		if (!bio)
 			break;
diff --git a/libbcachefs/io.h b/libbcachefs/io.h
index fb6f300..619bf56 100644
--- a/libbcachefs/io.h
+++ b/libbcachefs/io.h
@@ -41,11 +41,18 @@ static inline struct write_point *foreground_write_point(struct bch_fs *c,
 }
 
 void bch2_write_op_init(struct bch_write_op *, struct bch_fs *,
-			struct bch_write_bio *,
 			struct disk_reservation, struct write_point *,
 			struct bpos, u64 *, unsigned);
 void bch2_write(struct closure *);
 
+static inline struct bch_write_bio *wbio_init(struct bio *bio)
+{
+	struct bch_write_bio *wbio = to_wbio(bio);
+
+	memset(wbio, 0, offsetof(struct bch_write_bio, bio));
+	return wbio;
+}
+
 struct cache_promote_op;
 
 struct extent_pick_ptr;
diff --git a/libbcachefs/io_types.h b/libbcachefs/io_types.h
index d104cb7..3b73bcf 100644
--- a/libbcachefs/io_types.h
+++ b/libbcachefs/io_types.h
@@ -66,37 +66,30 @@ struct bch_write_bio {
 	struct bch_fs		*c;
 	struct bch_dev		*ca;
 	union {
-		struct bio	*orig;
-		struct closure	*cl;
+	struct bch_write_bio	*parent;
+	struct closure		*cl;
 	};
 
-	unsigned		submit_time_us;
+	u8			ptr_idx;
+	u8			replicas_failed;
+	u8			order;
+
 	unsigned		split:1,
 				bounce:1,
 				put_bio:1,
-				have_io_ref:1;
+				have_io_ref:1,
+				used_mempool:1;
 
-	/* Only for btree writes: */
-	unsigned		used_mempool:1;
-	u8			order;
+	unsigned		submit_time_us;
+	void			*data;
 
 	struct bio		bio;
 };
 
-struct bch_replace_info {
-	struct extent_insert_hook	hook;
-	/* How many insertions succeeded */
-	unsigned			successes;
-	/* How many insertions failed */
-	unsigned			failures;
-	BKEY_PADDED(key);
-};
-
 struct bch_write_op {
 	struct closure		cl;
-	struct bch_fs	*c;
+	struct bch_fs		*c;
 	struct workqueue_struct	*io_wq;
-	struct bch_write_bio	*bio;
 
 	unsigned		written; /* sectors */
 
@@ -141,6 +134,9 @@ struct bch_write_op {
 
 	struct keylist		insert_keys;
 	u64			inline_keys[BKEY_EXTENT_U64s_MAX * 2];
+
+	/* Must be last: */
+	struct bch_write_bio	wbio;
 };
 
 #endif /* _BCACHE_IO_TYPES_H */
diff --git a/libbcachefs/journal.c b/libbcachefs/journal.c
index b0011b4..bf8c152 100644
--- a/libbcachefs/journal.c
+++ b/libbcachefs/journal.c
@@ -53,15 +53,15 @@ static inline u64 journal_pin_seq(struct journal *j,
 	return last_seq(j) + fifo_entry_idx(&j->pin, pin_list);
 }
 
-static inline void bch2_journal_add_entry(struct journal_buf *buf,
-					 const void *data, size_t u64s,
-					 unsigned type, enum btree_id id,
-					 unsigned level)
+static inline void bch2_journal_add_entry_noreservation(struct journal_buf *buf,
+				 unsigned type, enum btree_id id,
+				 unsigned level,
+				 const void *data, size_t u64s)
 {
 	struct jset *jset = buf->data;
 
-	bch2_journal_add_entry_at(buf, data, u64s, type, id, level,
-				 le32_to_cpu(jset->u64s));
+	bch2_journal_add_entry_at(buf, le32_to_cpu(jset->u64s),
+				  type, id, level, data, u64s);
 	le32_add_cpu(&jset->u64s, jset_u64s(u64s));
 }
 
@@ -97,8 +97,9 @@ static void bch2_journal_add_btree_root(struct journal_buf *buf,
 				       enum btree_id id, struct bkey_i *k,
 				       unsigned level)
 {
-	bch2_journal_add_entry(buf, k, k->k.u64s,
-			      JOURNAL_ENTRY_BTREE_ROOT, id, level);
+	bch2_journal_add_entry_noreservation(buf,
+			      JOURNAL_ENTRY_BTREE_ROOT, id, level,
+			      k, k->k.u64s);
 }
 
 static void journal_seq_blacklist_flush(struct journal *j,
@@ -416,13 +417,8 @@ static void journal_entry_null_range(void *start, void *end)
 {
 	struct jset_entry *entry;
 
-	for (entry = start; entry != end; entry = vstruct_next(entry)) {
-		entry->u64s	= 0;
-		entry->btree_id	= 0;
-		entry->level	= 0;
-		entry->flags	= 0;
-		SET_JOURNAL_ENTRY_TYPE(entry, 0);
-	}
+	for (entry = start; entry != end; entry = vstruct_next(entry))
+		memset(entry, 0, sizeof(*entry));
 }
 
 static int journal_validate_key(struct bch_fs *c, struct jset *j,
@@ -514,7 +510,7 @@ static int __journal_entry_validate(struct bch_fs *c, struct jset *j,
 			break;
 		}
 
-		switch (JOURNAL_ENTRY_TYPE(entry)) {
+		switch (entry->type) {
 		case JOURNAL_ENTRY_BTREE_KEYS:
 			vstruct_for_each(entry, k) {
 				ret = journal_validate_key(c, j, entry, k,
@@ -555,8 +551,8 @@ static int __journal_entry_validate(struct bch_fs *c, struct jset *j,
 
 			break;
 		default:
-			journal_entry_err(c, "invalid journal entry type %llu",
-				 JOURNAL_ENTRY_TYPE(entry));
+			journal_entry_err(c, "invalid journal entry type %u",
+					  entry->type);
 			journal_entry_null_range(entry, vstruct_next(entry));
 			break;
 		}
@@ -1426,9 +1422,9 @@ void bch2_journal_start(struct bch_fs *c)
 	 */
 	list_for_each_entry(bl, &j->seq_blacklist, list)
 		if (!bl->written) {
-			bch2_journal_add_entry(journal_cur_buf(j), &bl->seq, 1,
+			bch2_journal_add_entry_noreservation(journal_cur_buf(j),
 					JOURNAL_ENTRY_JOURNAL_SEQ_BLACKLISTED,
-					0, 0);
+					0, 0, &bl->seq, 1);
 
 			journal_pin_add_entry(j,
 					      &fifo_peek_back(&j->pin),
@@ -2083,8 +2079,8 @@ static void journal_write_compact(struct jset *jset)
 		if (prev &&
 		    i->btree_id == prev->btree_id &&
 		    i->level	== prev->level &&
-		    JOURNAL_ENTRY_TYPE(i) == JOURNAL_ENTRY_TYPE(prev) &&
-		    JOURNAL_ENTRY_TYPE(i) == JOURNAL_ENTRY_BTREE_KEYS &&
+		    i->type	== prev->type &&
+		    i->type	== JOURNAL_ENTRY_BTREE_KEYS &&
 		    le16_to_cpu(prev->u64s) + u64s <= U16_MAX) {
 			memmove_u64s_down(vstruct_next(prev),
 					  i->_data,
@@ -2238,8 +2234,9 @@ static void journal_write(struct closure *cl)
 		closure_return_with_destructor(cl, journal_write_done);
 	}
 
-	bch2_check_mark_super(c, bkey_i_to_s_c_extent(&j->key),
-			      BCH_DATA_JOURNAL);
+	if (bch2_check_mark_super(c, bkey_i_to_s_c_extent(&j->key),
+				  BCH_DATA_JOURNAL))
+		goto err;
 
 	/*
 	 * XXX: we really should just disable the entire journal in nochanges
diff --git a/libbcachefs/journal.h b/libbcachefs/journal.h
index 88a9bd1..d785a0c 100644
--- a/libbcachefs/journal.h
+++ b/libbcachefs/journal.h
@@ -125,7 +125,7 @@ static inline struct jset_entry *__jset_entry_type_next(struct jset *jset,
 					struct jset_entry *entry, unsigned type)
 {
 	while (entry < vstruct_last(jset)) {
-		if (JOURNAL_ENTRY_TYPE(entry) == type)
+		if (entry->type == type)
 			return entry;
 
 		entry = vstruct_next(entry);
@@ -187,8 +187,12 @@ static inline void journal_state_inc(union journal_res_state *s)
 	s->buf1_count += s->idx == 1;
 }
 
-static inline void bch2_journal_set_has_inode(struct journal_buf *buf, u64 inum)
+static inline void bch2_journal_set_has_inode(struct journal *j,
+					      struct journal_res *res,
+					      u64 inum)
 {
+	struct journal_buf *buf = &j->buf[res->idx];
+
 	set_bit(hash_64(inum, ilog2(sizeof(buf->has_inode) * 8)), buf->has_inode);
 }
 
@@ -202,40 +206,46 @@ static inline unsigned jset_u64s(unsigned u64s)
 }
 
 static inline void bch2_journal_add_entry_at(struct journal_buf *buf,
-					    const void *data, size_t u64s,
+					    unsigned offset,
 					    unsigned type, enum btree_id id,
-					    unsigned level, unsigned offset)
+					    unsigned level,
+					    const void *data, size_t u64s)
 {
 	struct jset_entry *entry = vstruct_idx(buf->data, offset);
 
-	entry->u64s = cpu_to_le16(u64s);
+	memset(entry, 0, sizeof(*entry));
+	entry->u64s	= cpu_to_le16(u64s);
 	entry->btree_id = id;
-	entry->level = level;
-	entry->flags = 0;
-	SET_JOURNAL_ENTRY_TYPE(entry, type);
+	entry->level	= level;
+	entry->type	= type;
 
 	memcpy_u64s(entry->_data, data, u64s);
 }
 
-static inline void bch2_journal_add_keys(struct journal *j, struct journal_res *res,
-					enum btree_id id, const struct bkey_i *k)
+static inline void bch2_journal_add_entry(struct journal *j, struct journal_res *res,
+					  unsigned type, enum btree_id id,
+					  unsigned level,
+					  const void *data, unsigned u64s)
 {
 	struct journal_buf *buf = &j->buf[res->idx];
-	unsigned actual = jset_u64s(k->k.u64s);
+	unsigned actual = jset_u64s(u64s);
 
 	EBUG_ON(!res->ref);
 	BUG_ON(actual > res->u64s);
 
-	bch2_journal_set_has_inode(buf, k->k.p.inode);
-
-	bch2_journal_add_entry_at(buf, k, k->k.u64s,
-				 JOURNAL_ENTRY_BTREE_KEYS, id,
-				 0, res->offset);
-
+	bch2_journal_add_entry_at(buf, res->offset, type,
+				  id, level, data, u64s);
 	res->offset	+= actual;
 	res->u64s	-= actual;
 }
 
+static inline void bch2_journal_add_keys(struct journal *j, struct journal_res *res,
+					enum btree_id id, const struct bkey_i *k)
+{
+	bch2_journal_add_entry(j, res, JOURNAL_ENTRY_BTREE_KEYS,
+			       id, 0, k, k->k.u64s);
+}
+
 void bch2_journal_buf_put_slowpath(struct journal *, bool);
 
 static inline void bch2_journal_buf_put(struct journal *j, unsigned idx,
@@ -272,13 +282,10 @@ static inline void bch2_journal_res_put(struct journal *j,
 
 	lock_release(&j->res_map, 0, _RET_IP_);
 
-	while (res->u64s) {
-		bch2_journal_add_entry_at(&j->buf[res->idx], NULL, 0,
-					 JOURNAL_ENTRY_BTREE_KEYS,
-					 0, 0, res->offset);
-		res->offset	+= jset_u64s(0);
-		res->u64s	-= jset_u64s(0);
-	}
+	while (res->u64s)
+		bch2_journal_add_entry(j, res,
+				       JOURNAL_ENTRY_BTREE_KEYS,
+				       0, 0, NULL, 0);
 
 	bch2_journal_buf_put(j, res->idx, false);
 
diff --git a/libbcachefs/migrate.c b/libbcachefs/migrate.c
index ba0cc0e..78f6d3c 100644
--- a/libbcachefs/migrate.c
+++ b/libbcachefs/migrate.c
@@ -128,9 +128,12 @@ int bch2_move_data_off_device(struct bch_dev *ca)
 			seen_key_count++;
 			continue;
 next:
-			if (bkey_extent_is_data(k.k))
-				bch2_check_mark_super(c, bkey_s_c_to_extent(k),
-						      BCH_DATA_USER);
+			if (bkey_extent_is_data(k.k)) {
+				ret = bch2_check_mark_super(c, bkey_s_c_to_extent(k),
+							    BCH_DATA_USER);
+				if (ret)
+					break;
+			}
 			bch2_btree_iter_advance_pos(&iter);
 			bch2_btree_iter_cond_resched(&iter);
 
@@ -386,9 +389,12 @@ int bch2_flag_data_bad(struct bch_dev *ca)
 		 */
 		continue;
 advance:
-		if (bkey_extent_is_data(k.k))
-			bch2_check_mark_super(c, bkey_s_c_to_extent(k),
-					      BCH_DATA_USER);
+		if (bkey_extent_is_data(k.k)) {
+			ret = bch2_check_mark_super(c, bkey_s_c_to_extent(k),
+						    BCH_DATA_USER);
+			if (ret)
+				break;
+		}
 		bch2_btree_iter_advance_pos(&iter);
 	}
 
diff --git a/libbcachefs/move.c b/libbcachefs/move.c
index 8c9395d..8ef1a0b 100644
--- a/libbcachefs/move.c
+++ b/libbcachefs/move.c
@@ -155,11 +155,8 @@ void bch2_migrate_write_init(struct bch_fs *c,
 	    (move_ptr && move_ptr->cached))
 		flags |= BCH_WRITE_CACHED;
 
-	bch2_write_op_init(&m->op, c, &m->wbio,
-			  (struct disk_reservation) { 0 },
-			  wp,
-			  bkey_start_pos(k.k),
-			  NULL, flags);
+	bch2_write_op_init(&m->op, c, (struct disk_reservation) { 0 }, wp,
+			  bkey_start_pos(k.k), NULL, flags);
 
 	if (m->move)
 		m->op.alloc_reserve = RESERVE_MOVINGGC;
@@ -194,7 +191,7 @@ static void moving_io_destructor(struct closure *cl)
 	atomic_sub(io->write.key.k.size, &ctxt->sectors_in_flight);
 	wake_up(&ctxt->wait);
 
-	bio_for_each_segment_all(bv, &io->write.wbio.bio, i)
+	bio_for_each_segment_all(bv, &io->write.op.wbio.bio, i)
 		if (bv->bv_page)
 			__free_page(bv->bv_page);
 
@@ -307,9 +304,7 @@ int bch2_data_move(struct bch_fs *c,
 		return -ENOMEM;
 	}
 
-	migrate_bio_init(io, &io->write.wbio.bio, k.k->size);
-	bio_get(&io->write.wbio.bio);
-	io->write.wbio.bio.bi_iter.bi_sector = bkey_start_offset(k.k);
+	migrate_bio_init(io, &io->write.op.wbio.bio, k.k->size);
 
 	bch2_migrate_write_init(c, &io->write, wp, k, move_ptr, 0);
 
diff --git a/libbcachefs/move.h b/libbcachefs/move.h
index 548f0f0..094eac8 100644
--- a/libbcachefs/move.h
+++ b/libbcachefs/move.h
@@ -19,7 +19,6 @@ struct migrate_write {
 	bool			move;
 	struct bch_extent_ptr	move_ptr;
 	struct bch_write_op	op;
-	struct bch_write_bio	wbio;
 };
 
 void bch2_migrate_write_init(struct bch_fs *,
diff --git a/libbcachefs/super-io.c b/libbcachefs/super-io.c
index 1eae0fc..0ddfad3 100644
--- a/libbcachefs/super-io.c
+++ b/libbcachefs/super-io.c
@@ -783,6 +783,12 @@ out:
 
 /* replica information: */
 
+static inline struct bch_replicas_cpu_entry *
+cpu_replicas_entry(struct bch_replicas_cpu *r, unsigned i)
+{
+	return (void *) r->entries + r->entry_size * i;
+}
+
 static inline struct bch_replicas_entry *
 replicas_entry_next(struct bch_replicas_entry *i)
 {
@@ -794,6 +800,24 @@ replicas_entry_next(struct bch_replicas_entry *i)
 	     (void *) (_i) < vstruct_end(&(_r)->field) && (_i)->data_type;\
 	     (_i) = replicas_entry_next(_i))
 
+static inline bool replicas_test_dev(struct bch_replicas_cpu_entry *e,
+				     unsigned dev)
+{
+	return (e->devs[dev >> 3] & (1 << (dev & 7))) != 0;
+}
+
+static inline void replicas_set_dev(struct bch_replicas_cpu_entry *e,
+				    unsigned dev)
+{
+	e->devs[dev >> 3] |= 1 << (dev & 7);
+}
+
+static inline unsigned replicas_dev_slots(struct bch_replicas_cpu *r)
+{
+	return (r->entry_size -
+		offsetof(struct bch_replicas_cpu_entry, devs)) * 8;
+}
+
 static void bch2_sb_replicas_nr_entries(struct bch_sb_field_replicas *r,
 					unsigned *nr,
 					unsigned *bytes,
@@ -879,6 +903,29 @@ static int bch2_sb_replicas_to_cpu_replicas(struct bch_fs *c)
 	return 0;
 }
 
+static void bkey_to_replicas(struct bkey_s_c_extent e,
+			     enum bch_data_types data_type,
+			     struct bch_replicas_cpu_entry *r,
+			     unsigned *max_dev)
+{
+	const struct bch_extent_ptr *ptr;
+
+	BUG_ON(!data_type ||
+	       data_type == BCH_DATA_SB ||
+	       data_type >= BCH_DATA_NR);
+
+	memset(r, 0, sizeof(*r));
+	r->data_type = data_type;
+
+	*max_dev = 0;
+
+	extent_for_each_ptr(e, ptr)
+		if (!ptr->cached) {
+			*max_dev = max_t(unsigned, *max_dev, ptr->dev);
+			replicas_set_dev(r, ptr->dev);
+		}
+}
+
 /*
  * for when gc of replica information is in progress:
  */
@@ -887,14 +934,11 @@ static int bch2_update_gc_replicas(struct bch_fs *c,
 				   struct bkey_s_c_extent e,
 				   enum bch_data_types data_type)
 {
-	const struct bch_extent_ptr *ptr;
-	struct bch_replicas_cpu_entry *new_e;
+	struct bch_replicas_cpu_entry new_e;
 	struct bch_replicas_cpu *new;
-	unsigned i, nr, entry_size, max_dev = 0;
+	unsigned i, nr, entry_size, max_dev;
 
-	extent_for_each_ptr(e, ptr)
-		if (!ptr->cached)
-			max_dev = max_t(unsigned, max_dev, ptr->dev);
+	bkey_to_replicas(e, data_type, &new_e, &max_dev);
 
 	entry_size = offsetof(struct bch_replicas_cpu_entry, devs) +
 		DIV_ROUND_UP(max_dev + 1, 8);
@@ -914,12 +958,9 @@ static int bch2_update_gc_replicas(struct bch_fs *c,
 		       cpu_replicas_entry(gc_r, i),
 		       gc_r->entry_size);
 
-	new_e = cpu_replicas_entry(new, nr - 1);
-	new_e->data_type = data_type;
-
-	extent_for_each_ptr(e, ptr)
-		if (!ptr->cached)
-			replicas_set_dev(new_e, ptr->dev);
+	memcpy(cpu_replicas_entry(new, nr - 1),
+	       &new_e,
+	       new->entry_size);
 
 	eytzinger0_sort(new->entries,
 			new->nr,
@@ -931,8 +972,38 @@ static int bch2_update_gc_replicas(struct bch_fs *c,
 	return 0;
 }
 
-int bch2_check_mark_super_slowpath(struct bch_fs *c, struct bkey_s_c_extent e,
-				   enum bch_data_types data_type)
+static bool replicas_has_extent(struct bch_replicas_cpu *r,
+				struct bkey_s_c_extent e,
+				enum bch_data_types data_type)
+{
+	struct bch_replicas_cpu_entry search;
+	unsigned max_dev;
+
+	bkey_to_replicas(e, data_type, &search, &max_dev);
+
+	return max_dev < replicas_dev_slots(r) &&
+		eytzinger0_find(r->entries, r->nr,
+				r->entry_size,
+				memcmp, &search) < r->nr;
+}
+
+bool bch2_sb_has_replicas(struct bch_fs *c, struct bkey_s_c_extent e,
+			  enum bch_data_types data_type)
+{
+	bool ret;
+
+	rcu_read_lock();
+	ret = replicas_has_extent(rcu_dereference(c->replicas),
+				  e, data_type);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+noinline
+static int bch2_check_mark_super_slowpath(struct bch_fs *c,
+					  struct bkey_s_c_extent e,
+					  enum bch_data_types data_type)
 {
 	struct bch_replicas_cpu *gc_r;
 	const struct bch_extent_ptr *ptr;
@@ -996,6 +1067,25 @@ err:
 	return ret;
 }
 
+int bch2_check_mark_super(struct bch_fs *c, struct bkey_s_c_extent e,
+			  enum bch_data_types data_type)
+{
+	struct bch_replicas_cpu *gc_r;
+	bool marked;
+
+	rcu_read_lock();
+	marked = replicas_has_extent(rcu_dereference(c->replicas),
+				     e, data_type) &&
+		(!(gc_r = rcu_dereference(c->replicas_gc)) ||
+		 replicas_has_extent(gc_r, e, data_type));
+	rcu_read_unlock();
+
+	if (marked)
+		return 0;
+
+	return bch2_check_mark_super_slowpath(c, e, data_type);
+}
+
 struct replicas_status __bch2_replicas_status(struct bch_fs *c,
 					      struct bch_dev *dev_to_offline)
 {
diff --git a/libbcachefs/super-io.h b/libbcachefs/super-io.h
index 879fdda..65dd9fb 100644
--- a/libbcachefs/super-io.h
+++ b/libbcachefs/super-io.h
@@ -121,92 +121,10 @@ const char *bch2_read_super(struct bcache_superblock *,
 			   struct bch_opts, const char *);
 void bch2_write_super(struct bch_fs *);
 
-static inline bool replicas_test_dev(struct bch_replicas_cpu_entry *e,
-				     unsigned dev)
-{
-	return (e->devs[dev >> 3] & (1 << (dev & 7))) != 0;
-}
-
-static inline void replicas_set_dev(struct bch_replicas_cpu_entry *e,
-				    unsigned dev)
-{
-	e->devs[dev >> 3] |= 1 << (dev & 7);
-}
-
-static inline unsigned replicas_dev_slots(struct bch_replicas_cpu *r)
-{
-	return (r->entry_size -
-		offsetof(struct bch_replicas_cpu_entry, devs)) * 8;
-}
-
-static inline struct bch_replicas_cpu_entry *
-cpu_replicas_entry(struct bch_replicas_cpu *r, unsigned i)
-{
-	return (void *) r->entries + r->entry_size * i;
-}
-
-int bch2_check_mark_super_slowpath(struct bch_fs *, struct bkey_s_c_extent,
-				   enum bch_data_types);
-
-static inline bool replicas_has_extent(struct bch_replicas_cpu *r,
-				       struct bkey_s_c_extent e,
-				       enum bch_data_types data_type)
-{
-	const struct bch_extent_ptr *ptr;
-	struct bch_replicas_cpu_entry search = {
-		.data_type = data_type,
-	};
-	unsigned max_dev = 0;
-
-	BUG_ON(!data_type ||
-	       data_type == BCH_DATA_SB ||
-	       data_type >= BCH_DATA_NR);
-
-	extent_for_each_ptr(e, ptr)
-		if (!ptr->cached) {
-			max_dev = max_t(unsigned, max_dev, ptr->dev);
-			replicas_set_dev(&search, ptr->dev);
-		}
-
-	return max_dev < replicas_dev_slots(r) &&
-		eytzinger0_find(r->entries, r->nr,
-				r->entry_size,
-				memcmp, &search) < r->nr;
-}
-
-static inline bool bch2_sb_has_replicas(struct bch_fs *c,
-					struct bkey_s_c_extent e,
-					enum bch_data_types data_type)
-{
-	bool ret;
-
-	rcu_read_lock();
-	ret = replicas_has_extent(rcu_dereference(c->replicas),
-				  e, data_type);
-	rcu_read_unlock();
-
-	return ret;
-}
-
-static inline int bch2_check_mark_super(struct bch_fs *c,
-					struct bkey_s_c_extent e,
-					enum bch_data_types data_type)
-{
-	struct bch_replicas_cpu *gc_r;
-	bool marked;
-
-	rcu_read_lock();
-	marked = replicas_has_extent(rcu_dereference(c->replicas),
-				     e, data_type) &&
-		(!(gc_r = rcu_dereference(c->replicas_gc)) ||
-		 replicas_has_extent(gc_r, e, data_type));
-	rcu_read_unlock();
-
-	if (marked)
-		return 0;
-
-	return bch2_check_mark_super_slowpath(c, e, data_type);
-}
+bool bch2_sb_has_replicas(struct bch_fs *, struct bkey_s_c_extent,
+			  enum bch_data_types);
+int bch2_check_mark_super(struct bch_fs *, struct bkey_s_c_extent,
+			  enum bch_data_types);
 
 struct replicas_status {
 	struct {
diff --git a/libbcachefs/super.c b/libbcachefs/super.c
index 692eb41..c4cb0b2 100644
--- a/libbcachefs/super.c
+++ b/libbcachefs/super.c
@@ -517,10 +517,15 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	mutex_init(&c->btree_interior_update_lock);
 
 	mutex_init(&c->bio_bounce_pages_lock);
+	mutex_init(&c->zlib_workspace_lock);
+
 	bio_list_init(&c->read_retry_list);
 	spin_lock_init(&c->read_retry_lock);
 	INIT_WORK(&c->read_retry_work, bch2_read_retry_work);
-	mutex_init(&c->zlib_workspace_lock);
+
+	bio_list_init(&c->btree_write_error_list);
+	spin_lock_init(&c->btree_write_error_lock);
+	INIT_WORK(&c->btree_write_error_work, bch2_btree_write_error_work);
 
 	INIT_LIST_HEAD(&c->fsck_errors);
 	mutex_init(&c->fsck_error_lock);
@@ -593,8 +598,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 				   PAGE_SECTORS, 0) ||
 	    !(c->usage_percpu = alloc_percpu(struct bch_fs_usage)) ||
 	    lg_lock_init(&c->usage_lock) ||
-	    mempool_init_page_pool(&c->btree_bounce_pool, 1,
-				   ilog2(btree_pages(c))) ||
+	    mempool_init_vp_pool(&c->btree_bounce_pool, 1, btree_bytes(c)) ||
 	    bdi_setup_and_register(&c->bdi, "bcachefs") ||
 	    bch2_io_clock_init(&c->io_clock[READ]) ||
 	    bch2_io_clock_init(&c->io_clock[WRITE]) ||
@@ -1345,11 +1349,13 @@ bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
 	}
 }
 
-static bool bch2_fs_may_start(struct bch_fs *c, int flags)
+static bool bch2_fs_may_start(struct bch_fs *c)
 {
 	struct replicas_status s;
 	struct bch_sb_field_members *mi;
-	unsigned i;
+	unsigned i, flags = c->opts.degraded
+		? BCH_FORCE_IF_DEGRADED
+		: 0;
 
 	if (!c->opts.degraded) {
 		mutex_lock(&c->sb_lock);
@@ -1773,7 +1779,7 @@ const char *bch2_fs_open(char * const *devices, unsigned nr_devices,
 	mutex_unlock(&c->sb_lock);
 
 	err = "insufficient devices";
-	if (!bch2_fs_may_start(c, 0))
+	if (!bch2_fs_may_start(c))
 		goto err;
 
 	if (!c->opts.nostart) {
@@ -1844,7 +1850,7 @@ static const char *__bch2_fs_open_incremental(struct bcache_superblock *sb,
 	}
 	mutex_unlock(&c->sb_lock);
 
-	if (!c->opts.nostart && bch2_fs_may_start(c, 0)) {
+	if (!c->opts.nostart && bch2_fs_may_start(c)) {
 		err = __bch2_fs_start(c);
 		if (err)
 			goto err;
diff --git a/libbcachefs/util.c b/libbcachefs/util.c
index 906e7a6..9a95854 100644
--- a/libbcachefs/util.c
+++ b/libbcachefs/util.c
@@ -577,3 +577,17 @@ void sort_cmp_size(void *base, size_t num, size_t size,
 		}
 	}
 }
+
+void mempool_free_vp(void *element, void *pool_data)
+{
+	size_t size = (size_t) pool_data;
+
+	vpfree(element, size);
+}
+
+void *mempool_alloc_vp(gfp_t gfp_mask, void *pool_data)
+{
+	size_t size = (size_t) pool_data;
+
+	return vpmalloc(size, gfp_mask);
+}
diff --git a/libbcachefs/util.h b/libbcachefs/util.h
index 68d9a86..a9a17d9 100644
--- a/libbcachefs/util.h
+++ b/libbcachefs/util.h
@@ -79,23 +79,43 @@ do {									\
 	(__builtin_types_compatible_p(typeof(_val), _type) ||		\
 	 __builtin_types_compatible_p(typeof(_val), const _type))
 
-static inline void kvpfree(void *p, size_t size)
+static inline void vpfree(void *p, size_t size)
 {
-	if (size < PAGE_SIZE)
-		kfree(p);
-	else if (is_vmalloc_addr(p))
+	if (is_vmalloc_addr(p))
 		vfree(p);
 	else
 		free_pages((unsigned long) p, get_order(size));
+}
 
+static inline void *vpmalloc(size_t size, gfp_t gfp_mask)
+{
+	return (void *) __get_free_pages(gfp_mask|__GFP_NOWARN,
+					 get_order(size)) ?:
+		__vmalloc(size, gfp_mask, PAGE_KERNEL);
+}
+
+static inline void kvpfree(void *p, size_t size)
+{
+	if (size < PAGE_SIZE)
+		kfree(p);
+	else
+		vpfree(p, size);
 }
 
 static inline void *kvpmalloc(size_t size, gfp_t gfp_mask)
 {
-	return size < PAGE_SIZE ? kmalloc(size, gfp_mask)
-		:  (void *) __get_free_pages(gfp_mask|__GFP_NOWARN,
-					     get_order(size))
-		?: __vmalloc(size, gfp_mask, PAGE_KERNEL);
+	return size < PAGE_SIZE
+		? kmalloc(size, gfp_mask)
+		: vpmalloc(size, gfp_mask);
+}
+
+void mempool_free_vp(void *element, void *pool_data);
+void *mempool_alloc_vp(gfp_t gfp_mask, void *pool_data);
+
+static inline int mempool_init_vp_pool(mempool_t *pool, int min_nr, size_t size)
+{
+	return mempool_init(pool, min_nr, mempool_alloc_vp,
+			    mempool_free_vp, (void *) size);
 }
 
 #define HEAP(type)							\
diff --git a/linux/sched.c b/linux/sched.c
index 11480f3..898ccb1 100644
--- a/linux/sched.c
+++ b/linux/sched.c
@@ -1,5 +1,6 @@
 
 #include <string.h>
+#include <sys/mman.h>
 
 #include <linux/math64.h>
 #include <linux/printk.h>
@@ -163,6 +164,8 @@ static void sched_init(void)
 {
 	struct task_struct *p = malloc(sizeof(*p));
 
+	mlockall(MCL_CURRENT|MCL_FUTURE);
+
 	memset(p, 0, sizeof(*p));
 
 	p->state	= TASK_RUNNING;