dm vdo: add synchronous metadata I/O submission helper

Add vdo_submit_metadata_vio_wait(), a synchronous I/O submission
helper that blocks until completion. This is needed for I/O during
early initialization before work queues are available.

Refactor read_geometry_block() to use it.

Signed-off-by: Bruce Johnston <bjohnsto@redhat.com>
Reviewed-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: bjohnsto

drivers/md/dm-vdo/io-submitter.c

@@ -364,6 +364,33 @@ void __submit_metadata_vio(struct vio *vio, physical_block_number_t physical,
 	vdo_launch_completion_with_priority(completion, get_metadata_priority(vio));
 }
 
+/**
+ * vdo_submit_metadata_vio_wait() - Submit I/O for a metadata vio and wait for completion.
+ * @vio: the vio for which to issue I/O
+ * @physical: the physical block number to read or write
+ * @operation: the type of I/O to perform
+ *
+ * The function operates similarly to __submit_metadata_vio except that it will
+ * block until the work is done. It can be used to do i/o before work queues
+ * and thread completions are set up.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+int vdo_submit_metadata_vio_wait(struct vio *vio,
+				 physical_block_number_t physical,
+				 blk_opf_t operation)
+{
+	int result;
+
+	result = vio_reset_bio(vio, vio->data, NULL, operation | REQ_META, physical);
+	if (result != VDO_SUCCESS)
+		return result;
+
+	bio_set_dev(vio->bio, vdo_get_backing_device(vio->completion.vdo));
+	submit_bio_wait(vio->bio);
+	return blk_status_to_errno(vio->bio->bi_status);
+}
+
 /**
  * vdo_make_io_submitter() - Create an io_submitter structure.
  * @thread_count: Number of bio-submission threads to set up.

drivers/md/dm-vdo/io-submitter.h

@@ -56,4 +56,8 @@ static inline void vdo_submit_flush_vio(struct vio *vio, bio_end_io_t callback,
 			      REQ_OP_WRITE | REQ_PREFLUSH, NULL, 0);
 }
 
+int vdo_submit_metadata_vio_wait(struct vio *vio,
+				 physical_block_number_t physical,
+				 blk_opf_t operation);
+
 #endif /* VDO_IO_SUBMITTER_H */

drivers/md/dm-vdo/vdo.c

@@ -295,29 +295,19 @@ static int initialize_super_block(struct vdo *vdo, struct vdo_super_block *super
  */
 static int __must_check read_geometry_block(struct vdo *vdo)
 {
-	struct vio *vio = &vdo->geometry_block.vio;
-	u8 *block = vdo->geometry_block.buffer;
 	int result;
 
 	/*
 	 * This is only safe because, having not already loaded the geometry, the vdo's geometry's
 	 * bio_offset field is 0, so the fact that vio_reset_bio() will subtract that offset from
 	 * the supplied pbn is not a problem.
 	 */
-	result = vio_reset_bio(vio, (char *)block, NULL, REQ_OP_READ,
-			       VDO_GEOMETRY_BLOCK_LOCATION);
+	result = vdo_submit_metadata_vio_wait(&vdo->geometry_block.vio,
+					      VDO_GEOMETRY_BLOCK_LOCATION, REQ_OP_READ);
 	if (result != VDO_SUCCESS)
 		return result;
 
-	bio_set_dev(vio->bio, vdo_get_backing_device(vdo));
-	submit_bio_wait(vio->bio);
-	result = blk_status_to_errno(vio->bio->bi_status);
-	if (result != 0) {
-		vdo_log_error_strerror(result, "synchronous read failed");
-		return -EIO;
-	}
-
-	return vdo_parse_geometry_block(block, &vdo->geometry);
+	return vdo_parse_geometry_block(vdo->geometry_block.buffer, &vdo->geometry);
 }
 
 static bool get_zone_thread_name(const thread_id_t thread_ids[], zone_count_t count,