bcachefs: bch2_bkey_get_iter() helpers

Introduce new helpers for a common pattern:

  bch2_trans_iter_init();
  bch2_btree_iter_peek_slot();

 - bch2_bkey_get_iter_type() returns -ENOENT if it doesn't find a key of
   the correct type
 - bch2_bkey_get_val_typed() copies the val out of the btree to a
   (typically stack allocated) variable; it handles the case where the
   value in the btree is smaller than the current version of the type,
   zeroing out the remainder.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 6 insertions, 9 deletions

diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index cf9f8c026034..439fa540323f 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -452,9 +452,8 @@ static int get_stripe_key_trans(struct btree_trans *trans, u64 idx,
 	struct bkey_s_c k;
 	int ret;
 
-	bch2_trans_iter_init(trans, &iter, BTREE_ID_stripes,
-			     POS(0, idx), BTREE_ITER_SLOTS);
-	k = bch2_btree_iter_peek_slot(&iter);
+	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
+			       POS(0, idx), BTREE_ITER_SLOTS);
 	ret = bkey_err(k);
 	if (ret)
 		goto err;
@@ -755,9 +754,8 @@ static int ec_stripe_delete(struct btree_trans *trans, u64 idx)
 	struct bkey_s_c_stripe s;
 	int ret;
 
-	bch2_trans_iter_init(trans, &iter, BTREE_ID_stripes, POS(0, idx),
-			     BTREE_ITER_INTENT);
-	k = bch2_btree_iter_peek_slot(&iter);
+	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes, POS(0, idx),
+			       BTREE_ITER_INTENT);
 	ret = bkey_err(k);
 	if (ret)
 		goto err;
@@ -835,9 +833,8 @@ static int ec_stripe_key_update(struct btree_trans *trans,
 	struct bkey_s_c k;
 	int ret;
 
-	bch2_trans_iter_init(trans, &iter, BTREE_ID_stripes,
-			     new->k.p, BTREE_ITER_INTENT);
-	k = bch2_btree_iter_peek_slot(&iter);
+	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
+			       new->k.p, BTREE_ITER_INTENT);
 	ret = bkey_err(k);
 	if (ret)
 		goto err;