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Commit 07741308 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: add barriers near done flag operations 



Somehow, I missed this little item in Documentation/atomic_ops.txt:
    *** WARNING: atomic_read() and atomic_set() DO NOT IMPLY BARRIERS! ***

Create and use some helper functions that include the proper memory
barriers for manipulating the done field.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent a14ea269

drivers/block/rbd.c

+24 −6
Original line number Diff line number Diff line
@@ -1216,10 +1216,28 @@ static int rbd_obj_request_wait(struct rbd_obj_request *obj_request) 
	return wait_for_completion_interruptible(&obj_request->completion);

}



static void obj_request_done_init(struct rbd_obj_request *obj_request)

{

	atomic_set(&obj_request->done, 0);

	smp_wmb();

}



static void obj_request_done_set(struct rbd_obj_request *obj_request)

{

	atomic_set(&obj_request->done, 1);

	smp_wmb();

}



static bool obj_request_done_test(struct rbd_obj_request *obj_request)

{

	smp_rmb();

	return atomic_read(&obj_request->done) != 0;

}



static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request,

				struct ceph_osd_op *op)

{

	atomic_set(&obj_request->done, 1);

	obj_request_done_set(obj_request);

}



static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
@@ -1249,14 +1267,14 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request, 
		xferred = obj_request->length;

	}

	obj_request->xferred = xferred;

	atomic_set(&obj_request->done, 1);

	obj_request_done_set(obj_request);

}



static void rbd_osd_write_callback(struct rbd_obj_request *obj_request,

				struct ceph_osd_op *op)

{

	obj_request->xferred = le64_to_cpu(op->extent.length);

	atomic_set(&obj_request->done, 1);

	obj_request_done_set(obj_request);

}



static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
@@ -1300,7 +1318,7 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req, 
		break;

	}



	if (atomic_read(&obj_request->done))

	if (obj_request_done_test(obj_request))

		rbd_obj_request_complete(obj_request);

}
@@ -1407,7 +1425,7 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name, 
	obj_request->which = BAD_WHICH;

	obj_request->type = type;

	INIT_LIST_HEAD(&obj_request->links);

	atomic_set(&obj_request->done, 0);

	obj_request_done_init(obj_request);

	init_completion(&obj_request->completion);

	kref_init(&obj_request->kref);
@@ -1611,7 +1629,7 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request) 
		rbd_assert(more);

		rbd_assert(which < img_request->obj_request_count);



		if (!atomic_read(&obj_request->done))

		if (!obj_request_done_test(obj_request))

			break;



		rbd_assert(obj_request->xferred <= (u64) UINT_MAX);