bcachefs: bch2_bkey_get_mut() now calls bch2_trans_update()

It's safe to call bch2_trans_update with a k/v pair where the value
hasn't been filled out, as long as the key part has been and the value
is filled out by transaction commit time.

This patch folds the bch2_trans_update() call into bch2_bkey_get_mut(),
eliminating a bit of boilerplate.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update.h

@@ -214,7 +214,7 @@ static inline struct bkey_i *bch2_bkey_make_mut(struct btree_trans *trans, struc
 	bkey_i_to_##_type(__bch2_bkey_make_mut(_trans, _k,		\
 				KEY_TYPE_##_type, sizeof(struct bkey_i_##_type)))
 
-static inline struct bkey_i *__bch2_bkey_get_mut(struct btree_trans *trans,
+static inline struct bkey_i *__bch2_bkey_get_mut_noupdate(struct btree_trans *trans,
 					 struct btree_iter *iter,
 					 unsigned btree_id, struct bpos pos,
 					 unsigned flags, unsigned type, unsigned min_bytes)
@@ -229,6 +229,35 @@ static inline struct bkey_i *__bch2_bkey_get_mut(struct btree_trans *trans,
 	return ret;
 }
 
+static inline struct bkey_i *bch2_bkey_get_mut_noupdate(struct btree_trans *trans,
+					       struct btree_iter *iter,
+					       unsigned btree_id, struct bpos pos,
+					       unsigned flags)
+{
+	return __bch2_bkey_get_mut_noupdate(trans, iter, btree_id, pos, flags, 0, 0);
+}
+
+static inline struct bkey_i *__bch2_bkey_get_mut(struct btree_trans *trans,
+					 struct btree_iter *iter,
+					 unsigned btree_id, struct bpos pos,
+					 unsigned flags, unsigned type, unsigned min_bytes)
+{
+	struct bkey_i *mut = __bch2_bkey_get_mut_noupdate(trans, iter,
+				btree_id, pos, flags|BTREE_ITER_INTENT, type, min_bytes);
+	int ret;
+
+	if (IS_ERR(mut))
+		return mut;
+
+	ret = bch2_trans_update(trans, iter, mut, flags);
+	if (ret) {
+		bch2_trans_iter_exit(trans, iter);
+		return ERR_PTR(ret);
+	}
+
+	return mut;
+}
+
 static inline struct bkey_i *bch2_bkey_get_mut_minsize(struct btree_trans *trans,
 						       struct btree_iter *iter,
 						       unsigned btree_id, struct bpos pos,
@@ -242,7 +271,7 @@ static inline struct bkey_i *bch2_bkey_get_mut(struct btree_trans *trans,
 					       unsigned btree_id, struct bpos pos,
 					       unsigned flags)
 {
-	return bch2_bkey_get_mut_minsize(trans, iter, btree_id, pos, flags, 0);
+	return __bch2_bkey_get_mut(trans, iter, btree_id, pos, flags, 0, 0);
 }
 
 #define bch2_bkey_get_mut_typed(_trans, _iter, _btree_id, _pos, _flags, _type)\

fs/bcachefs/buckets.c

@@ -1471,10 +1471,6 @@ static int bch2_trans_mark_stripe_ptr(struct btree_trans *trans,
 		stripe_blockcount_get(&s->v, p.ec.block) +
 		sectors);
 
-	ret = bch2_trans_update(trans, &iter, &s->k_i, 0);
-	if (ret)
-		goto err;
-
 	bch2_bkey_to_replicas(&r.e, bkey_i_to_s_c(&s->k_i));
 	r.e.data_type = data_type;
 	update_replicas_list(trans, &r.e, sectors);
@@ -1749,7 +1745,7 @@ static int __bch2_trans_mark_reflink_p(struct btree_trans *trans,
 	struct printbuf buf = PRINTBUF;
 	int ret;
 
-	k = bch2_bkey_get_mut(trans, &iter,
+	k = bch2_bkey_get_mut_noupdate(trans, &iter,
 			BTREE_ID_reflink, POS(0, *idx),
 			BTREE_ITER_WITH_UPDATES);
 	ret = PTR_ERR_OR_ZERO(k);

fs/bcachefs/io.c

@@ -257,7 +257,7 @@ static inline int bch2_extent_update_i_size_sectors(struct btree_trans *trans,
 	unsigned inode_update_flags = BTREE_UPDATE_NOJOURNAL;
 	int ret;
 
-	k = bch2_bkey_get_mut(trans, &iter, BTREE_ID_inodes,
+	k = bch2_bkey_get_mut_noupdate(trans, &iter, BTREE_ID_inodes,
 			      SPOS(0,
 				   extent_iter->pos.inode,
 				   extent_iter->snapshot),

fs/bcachefs/subvolume.c

@@ -369,7 +369,7 @@ static int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
 	ret = PTR_ERR_OR_ZERO(s);
 	if (unlikely(ret)) {
 		bch2_fs_inconsistent_on(ret == -ENOENT, trans->c, "missing snapshot %u", id);
-		goto err;
+		return ret;
 	}
 
 	/* already deleted? */
@@ -379,10 +379,6 @@ static int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
 	SET_BCH_SNAPSHOT_DELETED(&s->v, true);
 	SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
 	s->v.subvol = 0;
-
-	ret = bch2_trans_update(trans, &iter, &s->k_i, 0);
-	if (ret)
-		goto err;
 err:
 	bch2_trans_iter_exit(trans, &iter);
 	return ret;
@@ -434,10 +430,6 @@ static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)
 		    le32_to_cpu(parent->v.children[1]))
 			swap(parent->v.children[0],
 			     parent->v.children[1]);
-
-		ret = bch2_trans_update(trans, &p_iter, &parent->k_i, 0);
-		if (ret)
-			goto err;
 	}
 
 	ret = bch2_btree_delete_at(trans, &iter, 0);
@@ -888,30 +880,25 @@ int bch2_subvolume_unlink(struct btree_trans *trans, u32 subvolid)
 	struct subvolume_unlink_hook *h;
 	int ret = 0;
 
+	h = bch2_trans_kmalloc(trans, sizeof(*h));
+	ret = PTR_ERR_OR_ZERO(h);
+	if (ret)
+		return ret;
+
+	h->h.fn		= bch2_subvolume_wait_for_pagecache_and_delete_hook;
+	h->subvol	= subvolid;
+	bch2_trans_commit_hook(trans, &h->h);
+
 	n = bch2_bkey_get_mut_typed(trans, &iter,
 			BTREE_ID_subvolumes, POS(0, subvolid),
 			BTREE_ITER_CACHED, subvolume);
 	ret = PTR_ERR_OR_ZERO(n);
 	if (unlikely(ret)) {
 		bch2_fs_inconsistent_on(ret == -ENOENT, trans->c, "missing subvolume %u", subvolid);
-		goto err;
+		return ret;
 	}
 
 	SET_BCH_SUBVOLUME_UNLINKED(&n->v, true);
-
-	ret = bch2_trans_update(trans, &iter, &n->k_i, 0);
-	if (ret)
-		goto err;
-
-	h = bch2_trans_kmalloc(trans, sizeof(*h));
-	ret = PTR_ERR_OR_ZERO(h);
-	if (ret)
-		goto err;
-
-	h->h.fn		= bch2_subvolume_wait_for_pagecache_and_delete_hook;
-	h->subvol	= subvolid;
-	bch2_trans_commit_hook(trans, &h->h);
-err:
 	bch2_trans_iter_exit(trans, &iter);
 	return ret;
 }