]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/btree_iter.h
btree_write_buffer: ensure atomic64_sub_return_release availability
[bcachefs-tools-debian] / libbcachefs / btree_iter.h
index 7b47b8802413ec619fe35d4907f7d55ee8092a1a..5e103f519e62ec280863c389cb765904a6becb91 100644 (file)
@@ -4,8 +4,14 @@
 
 #include "bset.h"
 #include "btree_types.h"
+#include "trace.h"
 
-#include <trace/events/bcachefs.h>
+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_path *path, bool intent)
 {
@@ -36,14 +42,7 @@ static inline struct btree *btree_path_node(struct btree_path *path,
 static inline bool btree_node_lock_seq_matches(const struct btree_path *path,
                                        const struct btree *b, unsigned level)
 {
-       /*
-        * We don't compare the low bits of the lock sequence numbers because
-        * @path might have taken a write lock on @b, and we don't want to skip
-        * the linked path if the sequence numbers were equal before taking that
-        * write lock. The lock sequence number is incremented by taking and
-        * releasing write locks and is even when unlocked:
-        */
-       return path->l[level].lock_seq >> 1 == b->c.lock.state.seq >> 1;
+       return path->l[level].lock_seq == six_lock_seq(&b->c.lock);
 }
 
 static inline struct btree *btree_node_parent(struct btree_path *path,
@@ -54,6 +53,16 @@ static inline struct btree *btree_node_parent(struct btree_path *path,
 
 /* 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 struct btree_path *
 __trans_next_path(struct btree_trans *trans, unsigned idx)
 {
@@ -72,13 +81,43 @@ __trans_next_path(struct btree_trans *trans, unsigned idx)
        return &trans->paths[idx];
 }
 
-void bch2_btree_path_check_sort(struct btree_trans *, struct btree_path *, int);
-
-#define trans_for_each_path(_trans, _path)                             \
-       for (_path = __trans_next_path((_trans), 0);                    \
+#define trans_for_each_path_from(_trans, _path, _start)                        \
+       for (_path = __trans_next_path((_trans), _start);               \
             (_path);                                                   \
             _path = __trans_next_path((_trans), (_path)->idx + 1))
 
+#define trans_for_each_path(_trans, _path)                             \
+       trans_for_each_path_from(_trans, _path, 0)
+
+static inline struct btree_path *
+__trans_next_path_safe(struct btree_trans *trans, unsigned *idx)
+{
+       u64 l;
+
+       if (*idx == BTREE_ITER_MAX)
+               return NULL;
+
+       l = trans->paths_allocated >> *idx;
+       if (!l)
+               return NULL;
+
+       *idx += __ffs64(l);
+       EBUG_ON(*idx >= BTREE_ITER_MAX);
+       return &trans->paths[*idx];
+}
+
+/*
+ * 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_safe_from(_trans, _path, _idx, _start)     \
+       for (_idx = _start;                                             \
+            (_path = __trans_next_path_safe((_trans), &_idx));         \
+            _idx++)
+
+#define trans_for_each_path_safe(_trans, _path, _idx)                  \
+       trans_for_each_path_safe_from(_trans, _path, _idx, 0)
+
 static inline struct btree_path *next_btree_path(struct btree_trans *trans, struct btree_path *path)
 {
        unsigned idx = path ? path->sorted_idx + 1 : 0;
@@ -92,9 +131,10 @@ static inline struct btree_path *next_btree_path(struct btree_trans *trans, stru
 
 static inline struct btree_path *prev_btree_path(struct btree_trans *trans, struct btree_path *path)
 {
-       EBUG_ON(path->sorted_idx >= trans->nr_sorted);
-       return path->sorted_idx
-               ? trans->paths + trans->sorted[path->sorted_idx - 1]
+       unsigned idx = path ? path->sorted_idx : trans->nr_sorted;
+
+       return idx
+               ? trans->paths + trans->sorted[idx - 1]
                : NULL;
 }
 
@@ -103,6 +143,11 @@ static inline struct btree_path *prev_btree_path(struct btree_trans *trans, stru
             ((_path) = (_trans)->paths + trans->sorted[_i]), (_i) < (_trans)->nr_sorted;\
             _i++)
 
+#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)
 {
@@ -128,21 +173,84 @@ __trans_next_path_with_node(struct btree_trans *trans, struct btree *b,
             _path = __trans_next_path_with_node((_trans), (_b),        \
                                                 (_path)->idx + 1))
 
-struct btree_path * __must_check
-bch2_btree_path_make_mut(struct btree_trans *, struct btree_path *,
+struct btree_path *__bch2_btree_path_make_mut(struct btree_trans *, struct btree_path *,
                         bool, unsigned long);
+
+static inline struct btree_path * __must_check
+bch2_btree_path_make_mut(struct btree_trans *trans,
+                        struct btree_path *path, bool intent,
+                        unsigned long ip)
+{
+       if (path->ref > 1 || path->preserve)
+               path = __bch2_btree_path_make_mut(trans, path, intent, ip);
+       path->should_be_locked = false;
+       return path;
+}
+
 struct btree_path * __must_check
-bch2_btree_path_set_pos(struct btree_trans *, struct btree_path *,
-                       struct bpos, bool, unsigned long);
+__bch2_btree_path_set_pos(struct btree_trans *, struct btree_path *,
+                       struct bpos, bool, unsigned long, int);
+
+static inline struct btree_path * __must_check
+bch2_btree_path_set_pos(struct btree_trans *trans,
+                  struct btree_path *path, struct bpos new_pos,
+                  bool intent, unsigned long ip)
+{
+       int cmp = bpos_cmp(new_pos, path->pos);
+
+       return cmp
+               ? __bch2_btree_path_set_pos(trans, path, new_pos, intent, ip, cmp)
+               : path;
+}
+
+int __must_check bch2_btree_path_traverse_one(struct btree_trans *, struct btree_path *,
+                                             unsigned, unsigned long);
+
+static inline int __must_check bch2_btree_path_traverse(struct btree_trans *trans,
+                                         struct btree_path *path, unsigned flags)
+{
+       if (path->uptodate < BTREE_ITER_NEED_RELOCK)
+               return 0;
+
+       return bch2_btree_path_traverse_one(trans, path, flags, _RET_IP_);
+}
+
 int __must_check bch2_btree_path_traverse(struct btree_trans *,
                                          struct btree_path *, unsigned);
 struct btree_path *bch2_path_get(struct btree_trans *, enum btree_id, struct bpos,
                                 unsigned, unsigned, unsigned, unsigned long);
-inline struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *, struct bkey *);
+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);
+}
+
 #ifdef CONFIG_BCACHEFS_DEBUG
 void bch2_trans_verify_paths(struct btree_trans *);
 void bch2_assert_pos_locked(struct btree_trans *, enum btree_id,
@@ -164,27 +272,48 @@ int bch2_btree_path_relock_intent(struct btree_trans *, struct btree_path *);
 void bch2_path_put(struct btree_trans *, struct btree_path *, 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 *);
+bool bch2_trans_locked(struct btree_trans *);
 
-static inline bool trans_was_restarted(struct btree_trans *trans, u32 restart_count)
+static inline int trans_was_restarted(struct btree_trans *trans, u32 restart_count)
 {
-       return restart_count != trans->restart_count;
+       return restart_count != trans->restart_count
+               ? -BCH_ERR_transaction_restart_nested
+               : 0;
 }
 
-void bch2_trans_verify_not_restarted(struct btree_trans *, u32);
+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_in_restart_error(struct btree_trans *);
+
+static inline void bch2_trans_verify_not_in_restart(struct btree_trans *trans)
+{
+       if (trans->restarted)
+               bch2_trans_in_restart_error(trans);
+}
 
 __always_inline
-static inline int btree_trans_restart_nounlock(struct btree_trans *trans, int err)
+static int btree_trans_restart_nounlock(struct btree_trans *trans, int err)
 {
        BUG_ON(err <= 0);
-       BUG_ON(!bch2_err_matches(err, BCH_ERR_transaction_restart));
+       BUG_ON(!bch2_err_matches(-err, BCH_ERR_transaction_restart));
 
        trans->restarted = err;
+       trans->last_restarted_ip = _THIS_IP_;
        return -err;
 }
 
 __always_inline
-static inline int btree_trans_restart(struct btree_trans *trans, int err)
+static int btree_trans_restart(struct btree_trans *trans, int err)
 {
        btree_trans_restart_nounlock(trans, err);
        return -err;
@@ -213,6 +342,7 @@ int __must_check __bch2_btree_iter_traverse(struct btree_iter *iter);
 int __must_check bch2_btree_iter_traverse(struct btree_iter *);
 
 struct btree *bch2_btree_iter_peek_node(struct btree_iter *);
+struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *);
 struct btree *bch2_btree_iter_next_node(struct btree_iter *);
 
 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *, struct bpos);
@@ -273,8 +403,85 @@ static inline void bch2_btree_iter_set_snapshot(struct btree_iter *iter, u32 sna
 }
 
 void bch2_trans_iter_exit(struct btree_trans *, struct btree_iter *);
-void bch2_trans_iter_init(struct btree_trans *, struct btree_iter *,
-                         unsigned, struct bpos, unsigned);
+
+static inline unsigned __bch2_btree_iter_flags(struct btree_trans *trans,
+                                              unsigned btree_id,
+                                              unsigned flags)
+{
+       if (flags & BTREE_ITER_ALL_LEVELS)
+               flags |= BTREE_ITER_ALL_SNAPSHOTS|__BTREE_ITER_ALL_SNAPSHOTS;
+
+       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_ALL_SNAPSHOTS) &&
+           !btree_type_has_snapshots(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 unsigned bch2_btree_iter_flags(struct btree_trans *trans,
+                                            unsigned btree_id,
+                                            unsigned flags)
+{
+       if (!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;
+
+       return __bch2_btree_iter_flags(trans, btree_id, 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)
+{
+       memset(iter, 0, sizeof(*iter));
+       iter->trans     = trans;
+       iter->btree_id  = btree_id;
+       iter->flags     = flags;
+       iter->snapshot  = pos.snapshot;
+       iter->pos       = pos;
+       iter->k.p       = pos;
+
+#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, 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);
@@ -286,26 +493,108 @@ static inline void set_btree_iter_dontneed(struct btree_iter *iter)
                iter->path->preserve = false;
 }
 
-void *bch2_trans_kmalloc(struct btree_trans *, size_t);
-u32 bch2_trans_begin(struct btree_trans *);
+void *__bch2_trans_kmalloc(struct btree_trans *, size_t);
 
-static inline struct btree *
-__btree_iter_peek_node_and_restart(struct btree_trans *trans, struct btree_iter *iter)
+static inline void *bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
 {
-       struct btree *b;
+       size = roundup(size, 8);
 
-       while (b = bch2_btree_iter_peek_node(iter),
-              bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
-               bch2_trans_begin(trans);
+       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);
+       }
+}
+
+static inline void *bch2_trans_kmalloc_nomemzero(struct btree_trans *trans, size_t size)
+{
+       size = roundup(size, 8);
+
+       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);
+       }
+}
+
+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;
 
-       return b;
+       bch2_trans_iter_init(trans, iter, btree_id, pos, flags);
+       k = bch2_btree_iter_peek_slot(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 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;
+       int ret;
+
+       k = __bch2_bkey_get_iter(trans, &iter, btree_id, pos, flags, type);
+       ret = bkey_err(k);
+       if (!ret) {
+               unsigned b = min_t(unsigned, bkey_val_bytes(k.k), val_size);
+
+               memcpy(val, k.v, b);
+               if (unlikely(b < sizeof(*val)))
+                       memset((void *) val + b, 0, sizeof(*val) - b);
+               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 *);
+void bch2_trans_srcu_lock(struct btree_trans *);
+
+u32 bch2_trans_begin(struct btree_trans *);
+
+/*
+ * XXX
+ * this does not handle transaction restarts from bch2_btree_iter_next_node()
+ * correctly
+ */
 #define __for_each_btree_node(_trans, _iter, _btree_id, _start,                \
                              _locks_want, _depth, _flags, _b, _ret)    \
        for (bch2_trans_node_iter_init((_trans), &(_iter), (_btree_id), \
                                _start, _locks_want, _depth, _flags);   \
-            (_b) = __btree_iter_peek_node_and_restart((_trans), &(_iter)),\
+            (_b) = bch2_btree_iter_peek_node_and_restart(&(_iter)),    \
             !((_ret) = PTR_ERR_OR_ZERO(_b)) && (_b);                   \
             (_b) = bch2_btree_iter_next_node(&(_iter)))
 
@@ -314,11 +603,6 @@ __btree_iter_peek_node_and_restart(struct btree_trans *trans, struct btree_iter
        __for_each_btree_node(_trans, _iter, _btree_id, _start,         \
                              0, 0, _flags, _b, _ret)
 
-static inline int bkey_err(struct bkey_s_c k)
-{
-       return PTR_ERR_OR_ZERO(k.k);
-}
-
 static inline struct bkey_s_c bch2_btree_iter_peek_prev_type(struct btree_iter *iter,
                                                             unsigned flags)
 {
@@ -343,7 +627,7 @@ static inline struct bkey_s_c bch2_btree_iter_peek_upto_type(struct btree_iter *
        if (!(flags & BTREE_ITER_SLOTS))
                return bch2_btree_iter_peek_upto(iter, end);
 
-       if (bkey_cmp(iter->pos, end) > 0)
+       if (bkey_gt(iter->pos, end))
                return bkey_s_c_null;
 
        return bch2_btree_iter_peek_slot(iter);
@@ -359,6 +643,8 @@ static inline int btree_trans_too_many_iters(struct btree_trans *trans)
        return 0;
 }
 
+struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *);
+
 static inline struct bkey_s_c
 __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
                                   struct btree_iter *iter, unsigned flags)
@@ -373,20 +659,36 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
        return k;
 }
 
+static inline struct bkey_s_c
+__bch2_btree_iter_peek_upto_and_restart(struct btree_trans *trans,
+                                       struct btree_iter *iter,
+                                       struct bpos end,
+                                       unsigned flags)
+{
+       struct bkey_s_c k;
+
+       while (btree_trans_too_many_iters(trans) ||
+              (k = bch2_btree_iter_peek_upto_type(iter, end, flags),
+               bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
+               bch2_trans_begin(trans);
+
+       return k;
+}
+
 #define lockrestart_do(_trans, _do)                                    \
 ({                                                                     \
        u32 _restart_count;                                             \
-       int _ret                                                      \
+       int _ret2;                                                      \
                                                                        \
        do {                                                            \
                _restart_count = bch2_trans_begin(_trans);              \
-               _ret = (_do);                                           \
-       } while (bch2_err_matches(_ret, BCH_ERR_transaction_restart));  \
+               _ret2 = (_do);                                          \
+       } while (bch2_err_matches(_ret2, BCH_ERR_transaction_restart)); \
                                                                        \
-       if (!_ret                                                     \
+       if (!_ret2)                                                     \
                bch2_trans_verify_not_restarted(_trans, _restart_count);\
                                                                        \
-       _ret                                                          \
+       _ret2;                                                          \
 })
 
 /*
@@ -401,42 +703,39 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
 #define nested_lockrestart_do(_trans, _do)                             \
 ({                                                                     \
        u32 _restart_count, _orig_restart_count;                        \
-       int _ret                                                      \
+       int _ret2;                                                      \
                                                                        \
        _restart_count = _orig_restart_count = (_trans)->restart_count; \
                                                                        \
-       while (bch2_err_matches(_ret = (_do), BCH_ERR_transaction_restart))\
+       while (bch2_err_matches(_ret2 = (_do), BCH_ERR_transaction_restart))\
                _restart_count = bch2_trans_begin(_trans);              \
                                                                        \
-       if (!_ret                                                     \
+       if (!_ret2)                                                     \
                bch2_trans_verify_not_restarted(_trans, _restart_count);\
                                                                        \
-       if (!_ret && trans_was_restarted(_trans, _orig_restart_count))  \
-               _ret = -BCH_ERR_transaction_restart_nested;             \
-                                                                       \
-       _ret;                                                           \
+       _ret2 ?: trans_was_restarted(_trans, _restart_count);           \
 })
 
 #define for_each_btree_key2(_trans, _iter, _btree_id,                  \
                            _start, _flags, _k, _do)                    \
 ({                                                                     \
-       int _ret = 0;                                                   \
+       int _ret3 = 0;                                                  \
                                                                        \
        bch2_trans_iter_init((_trans), &(_iter), (_btree_id),           \
                             (_start), (_flags));                       \
                                                                        \
        while (1) {                                                     \
                u32 _restart_count = bch2_trans_begin(_trans);          \
+                                                                       \
+               _ret3 = 0;                                              \
                (_k) = bch2_btree_iter_peek_type(&(_iter), (_flags));   \
-               if (!(_k).k) {                                          \
-                       _ret = 0;                                       \
+               if (!(_k).k)                                            \
                        break;                                          \
-               }                                                       \
                                                                        \
-               _ret = bkey_err(_k) ?: (_do);                           \
-               if (bch2_err_matches(_ret, BCH_ERR_transaction_restart))\
+               _ret3 = bkey_err(_k) ?: (_do);                          \
+               if (bch2_err_matches(_ret3, BCH_ERR_transaction_restart))\
                        continue;                                       \
-               if (_ret                                              \
+               if (_ret3)                                              \
                        break;                                          \
                bch2_trans_verify_not_restarted(_trans, _restart_count);\
                if (!bch2_btree_iter_advance(&(_iter)))                 \
@@ -444,13 +743,43 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
        }                                                               \
                                                                        \
        bch2_trans_iter_exit((_trans), &(_iter));                       \
-       _ret;                                                           \
+       _ret3;                                                          \
+})
+
+#define for_each_btree_key2_upto(_trans, _iter, _btree_id,             \
+                           _start, _end, _flags, _k, _do)              \
+({                                                                     \
+       int _ret3 = 0;                                                  \
+                                                                       \
+       bch2_trans_iter_init((_trans), &(_iter), (_btree_id),           \
+                            (_start), (_flags));                       \
+                                                                       \
+       while (1) {                                                     \
+               u32 _restart_count = bch2_trans_begin(_trans);          \
+                                                                       \
+               _ret3 = 0;                                              \
+               (_k) = bch2_btree_iter_peek_upto_type(&(_iter), _end, (_flags));\
+               if (!(_k).k)                                            \
+                       break;                                          \
+                                                                       \
+               _ret3 = bkey_err(_k) ?: (_do);                          \
+               if (bch2_err_matches(_ret3, BCH_ERR_transaction_restart))\
+                       continue;                                       \
+               if (_ret3)                                              \
+                       break;                                          \
+               bch2_trans_verify_not_restarted(_trans, _restart_count);\
+               if (!bch2_btree_iter_advance(&(_iter)))                 \
+                       break;                                          \
+       }                                                               \
+                                                                       \
+       bch2_trans_iter_exit((_trans), &(_iter));                       \
+       _ret3;                                                          \
 })
 
 #define for_each_btree_key_reverse(_trans, _iter, _btree_id,           \
                                   _start, _flags, _k, _do)             \
 ({                                                                     \
-       int _ret = 0;                                                   \
+       int _ret3 = 0;                                                  \
                                                                        \
        bch2_trans_iter_init((_trans), &(_iter), (_btree_id),           \
                             (_start), (_flags));                       \
@@ -459,14 +788,14 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
                u32 _restart_count = bch2_trans_begin(_trans);          \
                (_k) = bch2_btree_iter_peek_prev_type(&(_iter), (_flags));\
                if (!(_k).k) {                                          \
-                       _ret = 0;                                       \
+                       _ret3 = 0;                                      \
                        break;                                          \
                }                                                       \
                                                                        \
-               _ret = bkey_err(_k) ?: (_do);                           \
-               if (bch2_err_matches(_ret, BCH_ERR_transaction_restart))\
+               _ret3 = bkey_err(_k) ?: (_do);                          \
+               if (bch2_err_matches(_ret3, BCH_ERR_transaction_restart))\
                        continue;                                       \
-               if (_ret                                              \
+               if (_ret3)                                              \
                        break;                                          \
                bch2_trans_verify_not_restarted(_trans, _restart_count);\
                if (!bch2_btree_iter_rewind(&(_iter)))                  \
@@ -474,7 +803,7 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
        }                                                               \
                                                                        \
        bch2_trans_iter_exit((_trans), &(_iter));                       \
-       _ret                                                          \
+       _ret3;                                                          \
 })
 
 #define for_each_btree_key_commit(_trans, _iter, _btree_id,            \
@@ -485,6 +814,22 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
                            (_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_upto_commit(_trans, _iter, _btree_id,       \
+                                 _start, _end, _iter_flags, _k,        \
+                                 _disk_res, _journal_seq, _commit_flags,\
+                                 _do)                                  \
+       for_each_btree_key2_upto(_trans, _iter, _btree_id, _start, _end, _iter_flags, _k,\
+                           (_do) ?: bch2_trans_commit(_trans, (_disk_res),\
+                                       (_journal_seq), (_commit_flags)))
+
 #define for_each_btree_key(_trans, _iter, _btree_id,                   \
                           _start, _flags, _k, _ret)                    \
        for (bch2_trans_iter_init((_trans), &(_iter), (_btree_id),      \
@@ -493,6 +838,15 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
             !((_ret) = bkey_err(_k)) && (_k).k;                        \
             bch2_btree_iter_advance(&(_iter)))
 
+#define for_each_btree_key_upto(_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_upto_and_restart((_trans),   \
+                                               &(_iter), _end, _flags),\
+            !((_ret) = bkey_err(_k)) && (_k).k;                        \
+            bch2_btree_iter_advance(&(_iter)))
+
 #define for_each_btree_key_norestart(_trans, _iter, _btree_id,         \
                           _start, _flags, _k, _ret)                    \
        for (bch2_trans_iter_init((_trans), &(_iter), (_btree_id),      \
@@ -521,6 +875,43 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
             !((_ret) = bkey_err(_k)) && (_k).k;                        \
             bch2_btree_iter_advance(&(_iter)))
 
+#define for_each_btree_key_upto_continue_norestart(_iter, _end, _flags, _k, _ret)\
+       for (;                                                                  \
+            (_k) = bch2_btree_iter_peek_upto_type(&(_iter), _end, _flags),     \
+            !((_ret) = bkey_err(_k)) && (_k).k;                                \
+            bch2_btree_iter_advance(&(_iter)))
+
+#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;                                                             \
+})
+
 /* new multiple iterator interface: */
 
 void bch2_trans_updates_to_text(struct printbuf *, struct btree_trans *);
@@ -528,10 +919,21 @@ void bch2_btree_path_to_text(struct printbuf *, struct btree_path *);
 void bch2_trans_paths_to_text(struct printbuf *, struct btree_trans *);
 void bch2_dump_trans_updates(struct btree_trans *);
 void bch2_dump_trans_paths_updates(struct btree_trans *);
-void __bch2_trans_init(struct btree_trans *, struct bch_fs *, const char *);
-void bch2_trans_exit(struct btree_trans *);
 
-#define bch2_trans_init(_trans, _c, _nr_iters, _mem) __bch2_trans_init(_trans, _c, __func__)
+struct btree_trans *__bch2_trans_get(struct bch_fs *, unsigned);
+void bch2_trans_put(struct btree_trans *);
+
+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);                             \
+})
 
 void bch2_btree_trans_to_text(struct printbuf *, struct btree_trans *);