drivers/block/drbd/drbd_req.c

Source file repositories/reference/linux-study-clean/drivers/block/drbd/drbd_req.c

File Facts

System
Linux kernel
Corpus path
drivers/block/drbd/drbd_req.c
Extension
.c
Size
56990 bytes
Lines
1792
Domain
Driver Families
Bucket
drivers/block
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct drbd_plug_cb {
	struct blk_plug_cb cb;
	struct drbd_request *most_recent_req;
	/* do we need more? */
};

static void drbd_unplug(struct blk_plug_cb *cb, bool from_schedule)
{
	struct drbd_plug_cb *plug = container_of(cb, struct drbd_plug_cb, cb);
	struct drbd_resource *resource = plug->cb.data;
	struct drbd_request *req = plug->most_recent_req;

	kfree(cb);
	if (!req)
		return;

	spin_lock_irq(&resource->req_lock);
	/* In case the sender did not process it yet, raise the flag to
	 * have it followed with P_UNPLUG_REMOTE just after. */
	req->rq_state |= RQ_UNPLUG;
	/* but also queue a generic unplug */
	drbd_queue_unplug(req->device);
	kref_put(&req->kref, drbd_req_destroy);
	spin_unlock_irq(&resource->req_lock);
}

static struct drbd_plug_cb* drbd_check_plugged(struct drbd_resource *resource)
{
	/* A lot of text to say
	 * return (struct drbd_plug_cb*)blk_check_plugged(); */
	struct drbd_plug_cb *plug;
	struct blk_plug_cb *cb = blk_check_plugged(drbd_unplug, resource, sizeof(*plug));

	if (cb)
		plug = container_of(cb, struct drbd_plug_cb, cb);
	else
		plug = NULL;
	return plug;
}

static void drbd_update_plug(struct drbd_plug_cb *plug, struct drbd_request *req)
{
	struct drbd_request *tmp = plug->most_recent_req;
	/* Will be sent to some peer.
	 * Remember to tag it with UNPLUG_REMOTE on unplug */
	kref_get(&req->kref);
	plug->most_recent_req = req;
	if (tmp)
		kref_put(&tmp->kref, drbd_req_destroy);
}

static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
{
	struct drbd_resource *resource = device->resource;
	struct drbd_peer_device *peer_device = first_peer_device(device);
	const int rw = bio_data_dir(req->master_bio);
	struct bio_and_error m = { NULL, };
	bool no_remote = false;
	bool submit_private_bio = false;

	spin_lock_irq(&resource->req_lock);
	if (rw == WRITE) {
		/* This may temporarily give up the req_lock,
		 * but will re-aquire it before it returns here.
		 * Needs to be before the check on drbd_suspended() */
		complete_conflicting_writes(req);
		/* no more giving up req_lock from now on! */

		/* check for congestion, and potentially stop sending
		 * full data updates, but start sending "dirty bits" only. */
		maybe_pull_ahead(device);
	}


	if (drbd_suspended(device)) {
		/* push back and retry: */
		req->rq_state |= RQ_POSTPONED;
		if (req->private_bio) {
			bio_put(req->private_bio);
			req->private_bio = NULL;
			put_ldev(device);
		}
		goto out;
	}

	/* We fail READ early, if we can not serve it.
	 * We must do this before req is registered on any lists.
	 * Otherwise, drbd_req_complete() will queue failed READ for retry. */
	if (rw != WRITE) {
		if (!do_remote_read(req) && !req->private_bio)

Annotation

Implementation Notes