bcachefs: Set PF_MEMALLOC_NOFS when trans->locked

proper lock ordering is: fs_reclaim -> btree node locks
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -996,7 +996,7 @@ static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 
 	bch2_trans_unlock(trans);
 	cond_resched();
-	trans->locked = true;
+	trans_set_locked(trans);
 
 	if (unlikely(trans->memory_allocation_failure)) {
 		struct closure cl;
@@ -3089,7 +3089,8 @@ u32 bch2_trans_begin(struct btree_trans *trans)
 		bch2_trans_srcu_unlock(trans);
 
 	trans->last_begin_ip = _RET_IP_;
-	trans->locked  = true;
+
+	trans_set_locked(trans);
 
 	if (trans->restarted) {
 		bch2_btree_path_traverse_all(trans);
@@ -3159,7 +3160,6 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
 	trans->last_begin_time	= local_clock();
 	trans->fn_idx		= fn_idx;
 	trans->locking_wait.task = current;
-	trans->locked		= true;
 	trans->journal_replay_not_finished =
 		unlikely(!test_bit(JOURNAL_replay_done, &c->journal.flags)) &&
 		atomic_inc_not_zero(&c->journal_keys.ref);
@@ -3193,6 +3193,7 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
 	trans->srcu_idx		= srcu_read_lock(&c->btree_trans_barrier);
 	trans->srcu_lock_time	= jiffies;
 	trans->srcu_held	= true;
+	trans_set_locked(trans);
 
 	closure_init_stack_release(&trans->ref);
 	return trans;

fs/bcachefs/btree_locking.c

@@ -792,7 +792,7 @@ static inline int __bch2_trans_relock(struct btree_trans *trans, bool trace)
 			return bch2_trans_relock_fail(trans, path, &f, trace);
 	}
 
-	trans->locked = true;
+	trans_set_locked(trans);
 out:
 	bch2_trans_verify_locks(trans);
 	return 0;
@@ -812,16 +812,14 @@ void bch2_trans_unlock_noassert(struct btree_trans *trans)
 {
 	__bch2_trans_unlock(trans);
 
-	trans->locked = false;
-	trans->last_unlock_ip = _RET_IP_;
+	trans_set_unlocked(trans);
 }
 
 void bch2_trans_unlock(struct btree_trans *trans)
 {
 	__bch2_trans_unlock(trans);
 
-	trans->locked = false;
-	trans->last_unlock_ip = _RET_IP_;
+	trans_set_unlocked(trans);
 }
 
 void bch2_trans_unlock_long(struct btree_trans *trans)

fs/bcachefs/btree_locking.h

@@ -193,6 +193,28 @@ int bch2_six_check_for_deadlock(struct six_lock *lock, void *p);
 
 /* lock: */
 
+static inline void trans_set_locked(struct btree_trans *trans)
+{
+	if (!trans->locked) {
+		trans->locked = true;
+		trans->last_unlock_ip = 0;
+
+		trans->pf_memalloc_nofs = (current->flags & PF_MEMALLOC_NOFS) != 0;
+		current->flags |= PF_MEMALLOC_NOFS;
+	}
+}
+
+static inline void trans_set_unlocked(struct btree_trans *trans)
+{
+	if (trans->locked) {
+		trans->locked = false;
+		trans->last_unlock_ip = _RET_IP_;
+
+		if (!trans->pf_memalloc_nofs)
+			current->flags &= ~PF_MEMALLOC_NOFS;
+	}
+}
+
 static inline int __btree_node_lock_nopath(struct btree_trans *trans,
 					 struct btree_bkey_cached_common *b,
 					 enum six_lock_type type,

fs/bcachefs/btree_types.h

@@ -484,6 +484,7 @@ struct btree_trans {
 	bool			lock_may_not_fail:1;
 	bool			srcu_held:1;
 	bool			locked:1;
+	bool			pf_memalloc_nofs:1;
 	bool			write_locked:1;
 	bool			used_mempool:1;
 	bool			in_traverse_all:1;