reftable: adapt writer_add_record() to propagate block_writer_add() errors

Previously, writer_add_record() would flush the current block and retry
appending the record whenever block_writer_add() returned any nonzero
error. This forced an assumption that every failure meant the block was
full, even when errors such as memory allocation or I/O failures occurred.

Update the writer_add_record() to inspect the error code returned by
block_writer_add() and only flush and reinitialize the writer when the
error is REFTABLE_ENTRY_TOO_BIG_ERROR. For any other error, immediately
propagate it.

Signed-off-by: Meet Soni <[email protected]>
Acked-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: inosmeet

reftable/writer.c

@@ -310,11 +310,12 @@ static int writer_add_record(struct reftable_writer *w,
 	 * done. Otherwise the block writer may have hit the block size limit
 	 * and needs to be flushed.
 	 */
-	if (!block_writer_add(w->block_writer, rec)) {
-		err = 0;
+	err = block_writer_add(w->block_writer, rec);
+	if (err == 0)
 		goto done;
-	}
 
+	if (err != REFTABLE_ENTRY_TOO_BIG_ERROR)
+		goto done;
 	/*
 	 * The current block is full, so we need to flush and reinitialize the
 	 * writer to start writing the next block.
@@ -329,16 +330,10 @@ static int writer_add_record(struct reftable_writer *w,
 	/*
 	 * Try to add the record to the writer again. If this still fails then
 	 * the record does not fit into the block size.
-	 *
-	 * TODO: it would be great to have `block_writer_add()` return proper
-	 *       error codes so that we don't have to second-guess the failure
-	 *       mode here.
 	 */
 	err = block_writer_add(w->block_writer, rec);
-	if (err) {
-		err = REFTABLE_ENTRY_TOO_BIG_ERROR;
+	if (err)
 		goto done;
-	}
 
 done:
 	return err;