Quelle  btree_iter.h   Sprache: C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_BTREE_ITER_H
#define _BCACHEFS_BTREE_ITER_H

#include "bset.h"
#include "btree_types.h"
#include "trace.h"

void bch2_trans_updates_to_text(struct printbuf *, struct btree_trans *);
void bch2_btree_path_to_text(struct printbuf *, struct btree_trans *, btree_path_idx_t);
void bch2_trans_paths_to_text(struct printbuf *, struct btree_trans *);
void bch2_dump_trans_paths_updates(struct btree_trans *);

static inline int __bkey_err(const struct bkey *k)
{
 return PTR_ERR_OR_ZERO(k);
}

#define bkey_err(_k) __bkey_err((_k).k)

static inline void __btree_path_get(struct btree_trans *trans, struct btree_path *path, bool intent)
{
 unsigned idx = path - trans->paths;

 EBUG_ON(idx >= trans->nr_paths);
 EBUG_ON(!test_bit(idx, trans->paths_allocated));
 if (unlikely(path->ref == U8_MAX)) {
  bch2_dump_trans_paths_updates(trans);
  panic("path %u refcount overflow\n", idx);
 }

 path->ref++;
 path->intent_ref += intent;
 trace_btree_path_get_ll(trans, path);
}

static inline bool __btree_path_put(struct btree_trans *trans, struct btree_path *path, bool intent)
{
 EBUG_ON(path - trans->paths >= trans->nr_paths);
 EBUG_ON(!test_bit(path - trans->paths, trans->paths_allocated));
 EBUG_ON(!path->ref);
 EBUG_ON(!path->intent_ref && intent);

 trace_btree_path_put_ll(trans, path);
 path->intent_ref -= intent;
 return --path->ref == 0;
}

static inline void btree_path_set_dirty(struct btree_trans *trans,
     struct btree_path *path,
     enum btree_path_uptodate u)
{
 BUG_ON(path->should_be_locked && trans->locked && !trans->restarted);
 path->uptodate = max_t(unsigned, path->uptodate, u);
}

static inline struct btree *btree_path_node(struct btree_path *path,
         unsigned level)
{
 return level < BTREE_MAX_DEPTH ? path->l[level].b : NULL;
}

static inline bool btree_node_lock_seq_matches(const struct btree_path *path,
     const struct btree *b, unsigned level)
{
 return path->l[level].lock_seq == six_lock_seq(&b->c.lock);
}

static inline struct btree *btree_node_parent(struct btree_path *path,
           struct btree *b)
{
 return btree_path_node(path, b->c.level + 1);
}

/* Iterate over paths within a transaction: */

void __bch2_btree_trans_sort_paths(struct btree_trans *);

static inline void btree_trans_sort_paths(struct btree_trans *trans)
{
 if (!IS_ENABLED(CONFIG_BCACHEFS_DEBUG) &&
     trans->paths_sorted)
  return;
 __bch2_btree_trans_sort_paths(trans);
}

static inline unsigned long *trans_paths_nr(struct btree_path *paths)
{
 return &container_of(paths, struct btree_trans_paths, paths[0])->nr_paths;
}

static inline unsigned long *trans_paths_allocated(struct btree_path *paths)
{
 unsigned long *v = trans_paths_nr(paths);
 return v - BITS_TO_LONGS(*v);
}

#define trans_for_each_path_idx_from(_paths_allocated, _nr, _idx, _start)\
 for (_idx = _start;      \
      (_idx = find_next_bit(_paths_allocated, _nr, _idx)) < _nr; \
      _idx++)

static inline struct btree_path *
__trans_next_path(struct btree_trans *trans, unsigned *idx)
{
 unsigned long *w = trans->paths_allocated + *idx / BITS_PER_LONG;
 /*
 * Open coded find_next_bit(), because
 *  - this is fast path, we can't afford the function call
 *  - and we know that nr_paths is a multiple of BITS_PER_LONG,
 */
 while (*idx < trans->nr_paths) {
  unsigned long v = *w >> (*idx & (BITS_PER_LONG - 1));
  if (v) {
   *idx += __ffs(v);
   return trans->paths + *idx;
  }

  *idx += BITS_PER_LONG;
  *idx &= ~(BITS_PER_LONG - 1);
  w++;
 }

 return NULL;
}

/*
 * This version is intended to be safe for use on a btree_trans that is owned by
 * another thread, for bch2_btree_trans_to_text();
 */
#define trans_for_each_path_from(_trans, _path, _idx, _start)  \
 for (_idx = _start;      \
      (_path = __trans_next_path((_trans), &_idx));  \
      _idx++)

#define trans_for_each_path(_trans, _path, _idx)   \
 trans_for_each_path_from(_trans, _path, _idx, 1)

static inline struct btree_path *next_btree_path(struct btree_trans *trans, struct btree_path *path)
{
 unsigned idx = path ? path->sorted_idx + 1 : 0;

 EBUG_ON(idx > trans->nr_sorted);

 return idx < trans->nr_sorted
  ? trans->paths + trans->sorted[idx]
  : NULL;
}

static inline struct btree_path *prev_btree_path(struct btree_trans *trans, struct btree_path *path)
{
 unsigned idx = path ? path->sorted_idx : trans->nr_sorted;

 return idx
  ? trans->paths + trans->sorted[idx - 1]
  : NULL;
}

#define trans_for_each_path_idx_inorder(_trans, _iter)   \
 for (_iter = (struct trans_for_each_path_inorder_iter) { 0 }; \
      (_iter.path_idx = trans->sorted[_iter.sorted_idx],  \
       _iter.sorted_idx < (_trans)->nr_sorted);   \
      _iter.sorted_idx++)

struct trans_for_each_path_inorder_iter {
 btree_path_idx_t sorted_idx;
 btree_path_idx_t path_idx;
};

#define trans_for_each_path_inorder(_trans, _path, _iter)  \
 for (_iter = (struct trans_for_each_path_inorder_iter) { 0 }; \
      (_iter.path_idx = trans->sorted[_iter.sorted_idx],  \
       _path = (_trans)->paths + _iter.path_idx,   \
       _iter.sorted_idx < (_trans)->nr_sorted);   \
      _iter.sorted_idx++)

#define trans_for_each_path_inorder_reverse(_trans, _path, _i)  \
 for (_i = trans->nr_sorted - 1;     \
      ((_path) = (_trans)->paths + trans->sorted[_i]), (_i) >= 0;\
      --_i)

static inline bool __path_has_node(const struct btree_path *path,
       const struct btree *b)
{
 return path->l[b->c.level].b == b &&
  btree_node_lock_seq_matches(path, b, b->c.level);
}

static inline struct btree_path *
__trans_next_path_with_node(struct btree_trans *trans, struct btree *b,
       unsigned *idx)
{
 struct btree_path *path;

 while ((path = __trans_next_path(trans, idx)) &&
  !__path_has_node(path, b))
        (*idx)++;

 return path;
}

#define trans_for_each_path_with_node(_trans, _b, _path, _iter)  \
 for (_iter = 1;       \
      (_path = __trans_next_path_with_node((_trans), (_b), &_iter));\
      _iter++)

btree_path_idx_t __bch2_btree_path_make_mut(struct btree_trans *, btree_path_idx_t,
         bool, unsigned long);

static inline btree_path_idx_t __must_check
bch2_btree_path_make_mut(struct btree_trans *trans,
    btree_path_idx_t path, bool intent,
    unsigned long ip)
{
 if (trans->paths[path].ref > 1 ||
     trans->paths[path].preserve)
  path = __bch2_btree_path_make_mut(trans, path, intent, ip);
 trans->paths[path].should_be_locked = false;
 return path;
}

btree_path_idx_t __must_check
__bch2_btree_path_set_pos(struct btree_trans *, btree_path_idx_t,
     struct bpos, bool, unsigned long);

static inline btree_path_idx_t __must_check
bch2_btree_path_set_pos(struct btree_trans *trans,
   btree_path_idx_t path, struct bpos new_pos,
   bool intent, unsigned long ip)
{
 return !bpos_eq(new_pos, trans->paths[path].pos)
  ? __bch2_btree_path_set_pos(trans, path, new_pos, intent, ip)
  : path;
}

int __must_check bch2_btree_path_traverse_one(struct btree_trans *,
           btree_path_idx_t,
           unsigned, unsigned long);

static inline void bch2_trans_verify_not_unlocked_or_in_restart(struct btree_trans *);

static inline int __must_check bch2_btree_path_traverse(struct btree_trans *trans,
       btree_path_idx_t path, unsigned flags)
{
 bch2_trans_verify_not_unlocked_or_in_restart(trans);

 if (trans->paths[path].uptodate < BTREE_ITER_NEED_RELOCK)
  return 0;

 return bch2_btree_path_traverse_one(trans, path, flags, _RET_IP_);
}

btree_path_idx_t bch2_path_get(struct btree_trans *, enum btree_id, struct bpos,
     unsigned, unsigned, unsigned, unsigned long);
btree_path_idx_t bch2_path_get_unlocked_mut(struct btree_trans *, enum btree_id,
         unsigned, struct bpos);

struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *, struct bkey *);

/*
 * bch2_btree_path_peek_slot() for a cached iterator might return a key in a
 * different snapshot:
 */
static inline struct bkey_s_c bch2_btree_path_peek_slot_exact(struct btree_path *path, struct bkey *u)
{
 struct bkey_s_c k = bch2_btree_path_peek_slot(path, u);

 if (k.k && bpos_eq(path->pos, k.k->p))
  return k;

 bkey_init(u);
 u->p = path->pos;
 return (struct bkey_s_c) { u, NULL };
}

struct bkey_i *bch2_btree_journal_peek_slot(struct btree_trans *,
     struct btree_iter *, struct bpos);

void bch2_btree_path_level_init(struct btree_trans *, struct btree_path *, struct btree *);

int __bch2_trans_mutex_lock(struct btree_trans *, struct mutex *);

static inline int bch2_trans_mutex_lock(struct btree_trans *trans, struct mutex *lock)
{
 return mutex_trylock(lock)
  ? 0
  : __bch2_trans_mutex_lock(trans, lock);
}

/* Debug: */

void __bch2_trans_verify_paths(struct btree_trans *);
void __bch2_assert_pos_locked(struct btree_trans *, enum btree_id, struct bpos);

static inline void bch2_trans_verify_paths(struct btree_trans *trans)
{
 if (static_branch_unlikely(&bch2_debug_check_iterators))
  __bch2_trans_verify_paths(trans);
}

static inline void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id btree,
       struct bpos pos)
{
 if (static_branch_unlikely(&bch2_debug_check_iterators))
  __bch2_assert_pos_locked(trans, btree, pos);
}

void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
          struct btree *, struct bkey_packed *);
void bch2_btree_node_iter_fix(struct btree_trans *trans, struct btree_path *,
         struct btree *, struct btree_node_iter *,
         struct bkey_packed *, unsigned, unsigned);

int bch2_btree_path_relock_intent(struct btree_trans *, struct btree_path *);

void bch2_path_put(struct btree_trans *, btree_path_idx_t, bool);

int bch2_trans_relock(struct btree_trans *);
int bch2_trans_relock_notrace(struct btree_trans *);
void bch2_trans_unlock(struct btree_trans *);
void bch2_trans_unlock_long(struct btree_trans *);

static inline int trans_was_restarted(struct btree_trans *trans, u32 restart_count)
{
 return restart_count != trans->restart_count
  ? -BCH_ERR_transaction_restart_nested
  : 0;
}

void __noreturn bch2_trans_restart_error(struct btree_trans *, u32);

static inline void bch2_trans_verify_not_restarted(struct btree_trans *trans,
         u32 restart_count)
{
 if (trans_was_restarted(trans, restart_count))
  bch2_trans_restart_error(trans, restart_count);
}

void __noreturn bch2_trans_unlocked_or_in_restart_error(struct btree_trans *);

static inline void bch2_trans_verify_not_unlocked_or_in_restart(struct btree_trans *trans)
{
 if (trans->restarted || !trans->locked)
  bch2_trans_unlocked_or_in_restart_error(trans);
}

__always_inline
static int btree_trans_restart_foreign_task(struct btree_trans *trans, int err, unsigned long ip)
{
 BUG_ON(err <= 0);
 BUG_ON(!bch2_err_matches(-err, BCH_ERR_transaction_restart));

 trans->restarted = err;
 trans->last_restarted_ip = ip;
 return -err;
}

__always_inline
static int btree_trans_restart_ip(struct btree_trans *trans, int err, unsigned long ip)
{
 btree_trans_restart_foreign_task(trans, err, ip);
#ifdef CONFIG_BCACHEFS_DEBUG
 darray_exit(&trans->last_restarted_trace);
 bch2_save_backtrace(&trans->last_restarted_trace, current, 0, GFP_NOWAIT);
#endif
 return -err;
}

__always_inline
static int btree_trans_restart(struct btree_trans *trans, int err)
{
 return btree_trans_restart_ip(trans, err, _THIS_IP_);
}

static inline int trans_maybe_inject_restart(struct btree_trans *trans, unsigned long ip)
{
#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS
 if (!(ktime_get_ns() & ~(~0ULL << min(63, (10 + trans->restart_count_this_trans))))) {
  trace_and_count(trans->c, trans_restart_injected, trans, ip);
  return btree_trans_restart_ip(trans,
     BCH_ERR_transaction_restart_fault_inject, ip);
 }
#endif
 return 0;
}

bool bch2_btree_node_upgrade(struct btree_trans *,
        struct btree_path *, unsigned);

void __bch2_btree_path_downgrade(struct btree_trans *, struct btree_path *, unsigned);

static inline void bch2_btree_path_downgrade(struct btree_trans *trans,
          struct btree_path *path)
{
 unsigned new_locks_want = path->level + !!path->intent_ref;

 if (path->locks_want > new_locks_want)
  __bch2_btree_path_downgrade(trans, path, new_locks_want);
}

void bch2_trans_downgrade(struct btree_trans *);

void bch2_trans_node_add(struct btree_trans *trans, struct btree_path *, struct btree *);
void bch2_trans_node_drop(struct btree_trans *trans, struct btree *);
void bch2_trans_node_reinit_iter(struct btree_trans *, struct btree *);

int __must_check __bch2_btree_iter_traverse(struct btree_trans *, struct btree_iter *);
int __must_check bch2_btree_iter_traverse(struct btree_trans *, struct btree_iter *);

struct btree *bch2_btree_iter_peek_node(struct btree_trans *, struct btree_iter *);
struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_trans *, struct btree_iter *);
struct btree *bch2_btree_iter_next_node(struct btree_trans *, struct btree_iter *);

struct bkey_s_c bch2_btree_iter_peek_max(struct btree_trans *, struct btree_iter *, struct bpos);
struct bkey_s_c bch2_btree_iter_next(struct btree_trans *, struct btree_iter *);

static inline struct bkey_s_c bch2_btree_iter_peek(struct btree_trans *trans,
         struct btree_iter *iter)
{
 return bch2_btree_iter_peek_max(trans, iter, SPOS_MAX);
}

struct bkey_s_c bch2_btree_iter_peek_prev_min(struct btree_trans *, struct btree_iter *, struct bpos);

static inline struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_trans *trans, struct btree_iter *iter)
{
 return bch2_btree_iter_peek_prev_min(trans, iter, POS_MIN);
}

struct bkey_s_c bch2_btree_iter_prev(struct btree_trans *, struct btree_iter *);

struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *, struct btree_iter *);
struct bkey_s_c bch2_btree_iter_next_slot(struct btree_trans *, struct btree_iter *);
struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_trans *, struct btree_iter *);

bool bch2_btree_iter_advance(struct btree_trans *, struct btree_iter *);
bool bch2_btree_iter_rewind(struct btree_trans *, struct btree_iter *);

static inline void __bch2_btree_iter_set_pos(struct btree_iter *iter, struct bpos new_pos)
{
 iter->k.type = KEY_TYPE_deleted;
 iter->k.p.inode  = iter->pos.inode = new_pos.inode;
 iter->k.p.offset = iter->pos.offset = new_pos.offset;
 iter->k.p.snapshot = iter->pos.snapshot = new_pos.snapshot;
 iter->k.size = 0;
}

static inline void bch2_btree_iter_set_pos(struct btree_trans *trans,
        struct btree_iter *iter, struct bpos new_pos)
{
 if (unlikely(iter->update_path))
  bch2_path_put(trans, iter->update_path,
         iter->flags & BTREE_ITER_intent);
 iter->update_path = 0;

 if (!(iter->flags & BTREE_ITER_all_snapshots))
  new_pos.snapshot = iter->snapshot;

 __bch2_btree_iter_set_pos(iter, new_pos);
}

static inline void bch2_btree_iter_set_pos_to_extent_start(struct btree_iter *iter)
{
 BUG_ON(!(iter->flags & BTREE_ITER_is_extents));
 iter->pos = bkey_start_pos(&iter->k);
}

static inline void bch2_btree_iter_set_snapshot(struct btree_trans *trans,
      struct btree_iter *iter, u32 snapshot)
{
 struct bpos pos = iter->pos;

 iter->snapshot = snapshot;
 pos.snapshot = snapshot;
 bch2_btree_iter_set_pos(trans, iter, pos);
}

void bch2_trans_iter_exit(struct btree_trans *, struct btree_iter *);

static inline unsigned bch2_btree_iter_flags(struct btree_trans *trans,
          unsigned btree_id,
          unsigned level,
          unsigned flags)
{
 if (level || !btree_id_cached(trans->c, btree_id)) {
  flags &= ~BTREE_ITER_cached;
  flags &= ~BTREE_ITER_with_key_cache;
 } else if (!(flags & BTREE_ITER_cached))
  flags |= BTREE_ITER_with_key_cache;

 if (!(flags & (BTREE_ITER_all_snapshots|BTREE_ITER_not_extents)) &&
     btree_id_is_extents(btree_id))
  flags |= BTREE_ITER_is_extents;

 if (!(flags & BTREE_ITER_snapshot_field) &&
     !btree_type_has_snapshot_field(btree_id))
  flags &= ~BTREE_ITER_all_snapshots;

 if (!(flags & BTREE_ITER_all_snapshots) &&
     btree_type_has_snapshots(btree_id))
  flags |= BTREE_ITER_filter_snapshots;

 if (trans->journal_replay_not_finished)
  flags |= BTREE_ITER_with_journal;

 return flags;
}

static inline void bch2_trans_iter_init_common(struct btree_trans *trans,
       struct btree_iter *iter,
       unsigned btree_id, struct bpos pos,
       unsigned locks_want,
       unsigned depth,
       unsigned flags,
       unsigned long ip)
{
 iter->update_path = 0;
 iter->key_cache_path = 0;
 iter->btree_id  = btree_id;
 iter->min_depth  = 0;
 iter->flags  = flags;
 iter->snapshot  = pos.snapshot;
 iter->pos  = pos;
 iter->k   = POS_KEY(pos);
 iter->journal_idx = 0;
#ifdef CONFIG_BCACHEFS_DEBUG
 iter->ip_allocated = ip;
#endif
 iter->path = bch2_path_get(trans, btree_id, iter->pos,
       locks_want, depth, flags, ip);
}

void bch2_trans_iter_init_outlined(struct btree_trans *, struct btree_iter *,
     enum btree_id, struct bpos, unsigned);

static inline void bch2_trans_iter_init(struct btree_trans *trans,
     struct btree_iter *iter,
     unsigned btree_id, struct bpos pos,
     unsigned flags)
{
 if (__builtin_constant_p(btree_id) &&
     __builtin_constant_p(flags))
  bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
    bch2_btree_iter_flags(trans, btree_id, 0, flags),
    _THIS_IP_);
 else
  bch2_trans_iter_init_outlined(trans, iter, btree_id, pos, flags);
}

void bch2_trans_node_iter_init(struct btree_trans *, struct btree_iter *,
          enum btree_id, struct bpos,
          unsigned, unsigned, unsigned);
void bch2_trans_copy_iter(struct btree_trans *, struct btree_iter *, struct btree_iter *);

void bch2_set_btree_iter_dontneed(struct btree_trans *, struct btree_iter *);

#ifdef CONFIG_BCACHEFS_TRANS_KMALLOC_TRACE
void bch2_trans_kmalloc_trace_to_text(struct printbuf *,
          darray_trans_kmalloc_trace *);
#endif

void *__bch2_trans_kmalloc(struct btree_trans *, size_t, unsigned long);

static inline void bch2_trans_kmalloc_trace(struct btree_trans *trans, size_t size,
         unsigned long ip)
{
#ifdef CONFIG_BCACHEFS_TRANS_KMALLOC_TRACE
 darray_push(&trans->trans_kmalloc_trace,
      ((struct trans_kmalloc_trace) { .ip = ip, .bytes = size }));
#endif
}

static __always_inline void *bch2_trans_kmalloc_nomemzero_ip(struct btree_trans *trans, size_t size,
          unsigned long ip)
{
 size = roundup(size, 8);

 bch2_trans_kmalloc_trace(trans, size, ip);

 if (likely(trans->mem_top + size <= trans->mem_bytes)) {
  void *p = trans->mem + trans->mem_top;

  trans->mem_top += size;
  return p;
 } else {
  return __bch2_trans_kmalloc(trans, size, ip);
 }
}

static __always_inline void *bch2_trans_kmalloc_ip(struct btree_trans *trans, size_t size,
       unsigned long ip)
{
 size = roundup(size, 8);

 bch2_trans_kmalloc_trace(trans, size, ip);

 if (likely(trans->mem_top + size <= trans->mem_bytes)) {
  void *p = trans->mem + trans->mem_top;

  trans->mem_top += size;
  memset(p, 0, size);
  return p;
 } else {
  return __bch2_trans_kmalloc(trans, size, ip);
 }
}

/**
 * bch2_trans_kmalloc - allocate memory for use by the current transaction
 *
 * Must be called after bch2_trans_begin, which on second and further calls
 * frees all memory allocated in this transaction
 */
static __always_inline void *bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
{
 return bch2_trans_kmalloc_ip(trans, size, _THIS_IP_);
}

static __always_inline void *bch2_trans_kmalloc_nomemzero(struct btree_trans *trans, size_t size)
{
 return bch2_trans_kmalloc_nomemzero_ip(trans, size, _THIS_IP_);
}

static inline struct bkey_s_c __bch2_bkey_get_iter(struct btree_trans *trans,
    struct btree_iter *iter,
    unsigned btree_id, struct bpos pos,
    unsigned flags, unsigned type)
{
 struct bkey_s_c k;

 bch2_trans_iter_init(trans, iter, btree_id, pos, flags);
 k = bch2_btree_iter_peek_slot(trans, iter);

 if (!bkey_err(k) && type && k.k->type != type)
  k = bkey_s_c_err(-BCH_ERR_ENOENT_bkey_type_mismatch);
 if (unlikely(bkey_err(k)))
  bch2_trans_iter_exit(trans, iter);
 return k;
}

static inline struct bkey_s_c bch2_bkey_get_iter(struct btree_trans *trans,
    struct btree_iter *iter,
    unsigned btree_id, struct bpos pos,
    unsigned flags)
{
 return __bch2_bkey_get_iter(trans, iter, btree_id, pos, flags, 0);
}

#define bch2_bkey_get_iter_typed(_trans, _iter, _btree_id, _pos, _flags, _type)\
 bkey_s_c_to_##_type(__bch2_bkey_get_iter(_trans, _iter,   \
           _btree_id, _pos, _flags, KEY_TYPE_##_type))

static inline void __bkey_val_copy(void *dst_v, unsigned dst_size, struct bkey_s_c src_k)
{
 unsigned b = min_t(unsigned, dst_size, bkey_val_bytes(src_k.k));
 memcpy(dst_v, src_k.v, b);
 if (unlikely(b < dst_size))
  memset(dst_v + b, 0, dst_size - b);
}

#define bkey_val_copy(_dst_v, _src_k)     \
do {         \
 BUILD_BUG_ON(!__typecheck(*_dst_v, *_src_k.v));   \
 __bkey_val_copy(_dst_v, sizeof(*_dst_v), _src_k.s_c);  \
} while (0)

static inline int __bch2_bkey_get_val_typed(struct btree_trans *trans,
    unsigned btree_id, struct bpos pos,
    unsigned flags, unsigned type,
    unsigned val_size, void *val)
{
 struct btree_iter iter;
 struct bkey_s_c k = __bch2_bkey_get_iter(trans, &iter, btree_id, pos, flags, type);
 int ret = bkey_err(k);
 if (!ret) {
  __bkey_val_copy(val, val_size, k);
  bch2_trans_iter_exit(trans, &iter);
 }

 return ret;
}

#define bch2_bkey_get_val_typed(_trans, _btree_id, _pos, _flags, _type, _val)\
 __bch2_bkey_get_val_typed(_trans, _btree_id, _pos, _flags, \
      KEY_TYPE_##_type, sizeof(*_val), _val)

void bch2_trans_srcu_unlock(struct btree_trans *);

u32 bch2_trans_begin(struct btree_trans *);

#define __for_each_btree_node(_trans, _iter, _btree_id, _start,   \
         _locks_want, _depth, _flags, _b, _do)  \
({          \
 bch2_trans_begin((_trans));      \
          \
 struct btree_iter _iter;      \
 bch2_trans_node_iter_init((_trans), &_iter, (_btree_id),  \
      _start, _locks_want, _depth, _flags);  \
 int _ret3 = 0;        \
 do {         \
  _ret3 = lockrestart_do((_trans), ({    \
   struct btree *_b = bch2_btree_iter_peek_node(_trans, &_iter);\
   if (!_b)      \
    break;      \
          \
   PTR_ERR_OR_ZERO(_b) ?: (_do);    \
  })) ?:        \
  lockrestart_do((_trans),     \
   PTR_ERR_OR_ZERO(bch2_btree_iter_next_node(_trans, &_iter)));\
 } while (!_ret3);       \
          \
 bch2_trans_iter_exit((_trans), &(_iter));    \
 _ret3;         \
})

#define for_each_btree_node(_trans, _iter, _btree_id, _start,  \
       _flags, _b, _do)    \
 __for_each_btree_node(_trans, _iter, _btree_id, _start, \
         0, 0, _flags, _b, _do)

static inline struct bkey_s_c bch2_btree_iter_peek_prev_type(struct btree_trans *trans,
            struct btree_iter *iter,
            unsigned flags)
{
 return  flags & BTREE_ITER_slots      ? bch2_btree_iter_peek_slot(trans, iter) :
      bch2_btree_iter_peek_prev(trans, iter);
}

static inline struct bkey_s_c bch2_btree_iter_peek_type(struct btree_trans *trans,
       struct btree_iter *iter,
       unsigned flags)
{
 return  flags & BTREE_ITER_slots      ? bch2_btree_iter_peek_slot(trans, iter) :
      bch2_btree_iter_peek(trans, iter);
}

static inline struct bkey_s_c bch2_btree_iter_peek_max_type(struct btree_trans *trans,
           struct btree_iter *iter,
           struct bpos end,
           unsigned flags)
{
 if (!(flags & BTREE_ITER_slots))
  return bch2_btree_iter_peek_max(trans, iter, end);

 if (bkey_gt(iter->pos, end))
  return bkey_s_c_null;

 return bch2_btree_iter_peek_slot(trans, iter);
}

int __bch2_btree_trans_too_many_iters(struct btree_trans *);

static inline int btree_trans_too_many_iters(struct btree_trans *trans)
{
 if (bitmap_weight(trans->paths_allocated, trans->nr_paths) > BTREE_ITER_NORMAL_LIMIT - 8)
  return __bch2_btree_trans_too_many_iters(trans);

 return 0;
}

/*
 * goto instead of loop, so that when used inside for_each_btree_key2()
 * break/continue work correctly
 */
#define lockrestart_do(_trans, _do)     \
({         \
 __label__ transaction_restart;     \
 u32 _restart_count;      \
 int _ret2;       \
transaction_restart:       \
 _restart_count = bch2_trans_begin(_trans);   \
 _ret2 = (_do);       \
         \
 if (bch2_err_matches(_ret2, BCH_ERR_transaction_restart)) \
  goto transaction_restart;    \
         \
 if (!_ret2)       \
  bch2_trans_verify_not_restarted(_trans, _restart_count);\
 _ret2;        \
})

/*
 * nested_lockrestart_do(), nested_commit_do():
 *
 * These are like lockrestart_do() and commit_do(), with two differences:
 *
 *  - We don't call bch2_trans_begin() unless we had a transaction restart
 *  - We return -BCH_ERR_transaction_restart_nested if we succeeded after a
 *  transaction restart
 */
#define nested_lockrestart_do(_trans, _do)    \
({         \
 u32 _restart_count, _orig_restart_count;   \
 int _ret2;       \
         \
 _restart_count = _orig_restart_count = (_trans)->restart_count; \
         \
 while (bch2_err_matches(_ret2 = (_do), BCH_ERR_transaction_restart))\
  _restart_count = bch2_trans_begin(_trans);  \
         \
 if (!_ret2)       \
  bch2_trans_verify_not_restarted(_trans, _restart_count);\
         \
 _ret2 ?: trans_was_restarted(_trans, _orig_restart_count);  \
})

#define for_each_btree_key_max_continue(_trans, _iter,   \
      _end, _flags, _k, _do)  \
({         \
 struct bkey_s_c _k;      \
 int _ret3 = 0;       \
         \
 do {        \
  _ret3 = lockrestart_do(_trans, ({   \
   (_k) = bch2_btree_iter_peek_max_type(_trans, &(_iter), \
      _end, (_flags)); \
   if (!(_k).k)     \
    break;     \
         \
   bkey_err(_k) ?: (_do);    \
  }));       \
 } while (!_ret3 && bch2_btree_iter_advance(_trans, &(_iter))); \
         \
 bch2_trans_iter_exit((_trans), &(_iter));   \
 _ret3;        \
})

#define for_each_btree_key_continue(_trans, _iter, _flags, _k, _do) \
 for_each_btree_key_max_continue(_trans, _iter, SPOS_MAX, _flags, _k, _do)

#define for_each_btree_key_max(_trans, _iter, _btree_id,  \
    _start, _end, _flags, _k, _do)  \
({         \
 bch2_trans_begin(trans);     \
         \
 struct btree_iter _iter;     \
 bch2_trans_iter_init((_trans), &(_iter), (_btree_id),  \
        (_start), (_flags));   \
         \
 for_each_btree_key_max_continue(_trans, _iter, _end, _flags, _k, _do);\
})

#define for_each_btree_key(_trans, _iter, _btree_id,   \
      _start, _flags, _k, _do)   \
 for_each_btree_key_max(_trans, _iter, _btree_id, _start, \
     SPOS_MAX, _flags, _k, _do)

#define for_each_btree_key_reverse(_trans, _iter, _btree_id,  \
       _start, _flags, _k, _do)  \
({         \
 struct btree_iter _iter;     \
 struct bkey_s_c _k;      \
 int _ret3 = 0;       \
         \
 bch2_trans_iter_init((_trans), &(_iter), (_btree_id),  \
        (_start), (_flags));   \
         \
 do {        \
  _ret3 = lockrestart_do(_trans, ({   \
   (_k) = bch2_btree_iter_peek_prev_type(_trans, &(_iter), \
       (_flags)); \
   if (!(_k).k)     \
    break;     \
         \
   bkey_err(_k) ?: (_do);    \
  }));       \
 } while (!_ret3 && bch2_btree_iter_rewind(_trans, &(_iter))); \
         \
 bch2_trans_iter_exit((_trans), &(_iter));   \
 _ret3;        \
})

#define for_each_btree_key_commit(_trans, _iter, _btree_id,  \
      _start, _iter_flags, _k,  \
      _disk_res, _journal_seq, _commit_flags,\
      _do)     \
 for_each_btree_key(_trans, _iter, _btree_id, _start, _iter_flags, _k,\
       (_do) ?: bch2_trans_commit(_trans, (_disk_res),\
     (_journal_seq), (_commit_flags)))

#define for_each_btree_key_reverse_commit(_trans, _iter, _btree_id, \
      _start, _iter_flags, _k,  \
      _disk_res, _journal_seq, _commit_flags,\
      _do)     \
 for_each_btree_key_reverse(_trans, _iter, _btree_id, _start, _iter_flags, _k,\
       (_do) ?: bch2_trans_commit(_trans, (_disk_res),\
     (_journal_seq), (_commit_flags)))

#define for_each_btree_key_max_commit(_trans, _iter, _btree_id, \
      _start, _end, _iter_flags, _k, \
      _disk_res, _journal_seq, _commit_flags,\
      _do)     \
 for_each_btree_key_max(_trans, _iter, _btree_id, _start, _end, _iter_flags, _k,\
       (_do) ?: bch2_trans_commit(_trans, (_disk_res),\
     (_journal_seq), (_commit_flags)))

struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_trans *,
         struct btree_iter *);

#define for_each_btree_key_max_norestart(_trans, _iter, _btree_id, \
      _start, _end, _flags, _k, _ret)  \
 for (bch2_trans_iter_init((_trans), &(_iter), (_btree_id), \
      (_start), (_flags));   \
      (_k) = bch2_btree_iter_peek_max_type(_trans, &(_iter), _end, _flags),\
      !((_ret) = bkey_err(_k)) && (_k).k;   \
      bch2_btree_iter_advance(_trans, &(_iter)))

#define for_each_btree_key_max_continue_norestart(_trans, _iter, _end, _flags, _k, _ret)\
 for (;         \
      (_k) = bch2_btree_iter_peek_max_type(_trans, &(_iter), _end, _flags), \
      !((_ret) = bkey_err(_k)) && (_k).k;    \
      bch2_btree_iter_advance(_trans, &(_iter)))

#define for_each_btree_key_norestart(_trans, _iter, _btree_id,  \
      _start, _flags, _k, _ret)   \
 for_each_btree_key_max_norestart(_trans, _iter, _btree_id, _start,\
       SPOS_MAX, _flags, _k, _ret)

#define for_each_btree_key_reverse_norestart(_trans, _iter, _btree_id,  \
          _start, _flags, _k, _ret)  \
 for (bch2_trans_iter_init((_trans), &(_iter), (_btree_id),  \
      (_start), (_flags));    \
      (_k) = bch2_btree_iter_peek_prev_type(_trans, &(_iter), _flags), \
      !((_ret) = bkey_err(_k)) && (_k).k;    \
      bch2_btree_iter_rewind(_trans, &(_iter)))

#define for_each_btree_key_continue_norestart(_trans, _iter, _flags, _k, _ret) \
 for_each_btree_key_max_continue_norestart(_trans, _iter, SPOS_MAX, _flags, _k, _ret)

/*
 * This should not be used in a fastpath, without first trying _do in
 * nonblocking mode - it will cause excessive transaction restarts and
 * potentially livelocking:
 */
#define drop_locks_do(_trans, _do)     \
({         \
 bch2_trans_unlock(_trans);     \
 (_do) ?: bch2_trans_relock(_trans);    \
})

#define allocate_dropping_locks_errcode(_trans, _do)   \
({         \
 gfp_t _gfp = GFP_NOWAIT|__GFP_NOWARN;    \
 int _ret = _do;       \
         \
 if (bch2_err_matches(_ret, ENOMEM)) {    \
  _gfp = GFP_KERNEL;     \
  _ret = drop_locks_do(_trans, _do);   \
 }        \
 _ret;        \
})

#define allocate_dropping_locks(_trans, _ret, _do)   \
({         \
 gfp_t _gfp = GFP_NOWAIT|__GFP_NOWARN;    \
 typeof(_do) _p = _do;      \
         \
 _ret = 0;       \
 if (unlikely(!_p)) {      \
  _gfp = GFP_KERNEL;     \
  _ret = drop_locks_do(_trans, ((_p = _do), 0));  \
 }        \
 _p;        \
})

struct btree_trans *__bch2_trans_get(struct bch_fs *, unsigned);
void bch2_trans_put(struct btree_trans *);

bool bch2_current_has_btree_trans(struct bch_fs *);

extern const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR];
unsigned bch2_trans_get_fn_idx(const char *);

#define bch2_trans_get(_c)      \
({         \
 static unsigned trans_fn_idx;     \
         \
 if (unlikely(!trans_fn_idx))     \
  trans_fn_idx = bch2_trans_get_fn_idx(__func__);  \
 __bch2_trans_get(_c, trans_fn_idx);    \
})

/*
 * We don't use DEFINE_CLASS() because using a function for the constructor
 * breaks bch2_trans_get()'s use of __func__
 */
typedef struct btree_trans * class_btree_trans_t;
static inline void class_btree_trans_destructor(struct btree_trans **p)
{
 struct btree_trans *trans = *p;
 bch2_trans_put(trans);
}

#define class_btree_trans_constructor(_c) bch2_trans_get(_c)

#define bch2_trans_run(_c, _do)      \
({         \
 CLASS(btree_trans, trans)(_c);     \
 (_do);        \
})

#define bch2_trans_do(_c, _do) bch2_trans_run(_c, lockrestart_do(trans, _do))

void bch2_btree_trans_to_text(struct printbuf *, struct btree_trans *);

void bch2_fs_btree_iter_exit(struct bch_fs *);
void bch2_fs_btree_iter_init_early(struct bch_fs *);
int bch2_fs_btree_iter_init(struct bch_fs *);

#endif /* _BCACHEFS_BTREE_ITER_H */