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Commit 3c5df893 authored by Josh Durgin's avatar Josh Durgin Committed by Ilya Dryomov
Browse files

rbd: read image size for discard check safely 



In rbd_img_request_fill() the image size is only checked to determine
whether we can truncate an object instead of zeroing it for discard
requests. Take rbd_dev->header_rwsem while reading the image size, and
move this read into the discard check, so that non-discard ops don't
need to take the semaphore in this function.

Signed-off-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 90e98c52

drivers/block/rbd.c

+12 −6
Original line number Original line Diff line number Diff line
@@ -2332,7 +2332,6 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request, 
		(int)type, data_desc);

		(int)type, data_desc);





	img_offset = img_request->offset;

	img_offset = img_request->offset;

	img_end = rbd_dev->header.image_size;

	resid = img_request->length;

	resid = img_request->length;

	rbd_assert(resid > 0);

	rbd_assert(resid > 0);
@@ -2397,13 +2396,20 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request, 
			if (!offset && (length == object_size)

			if (!offset && (length == object_size)

				&& (!img_request_layered_test(img_request) ||

				&& (!img_request_layered_test(img_request) ||

					(rbd_dev->parent_overlap <=

					(rbd_dev->parent_overlap <=

						obj_request->img_offset)))

						obj_request->img_offset))) {

				opcode = CEPH_OSD_OP_DELETE;

				opcode = CEPH_OSD_OP_DELETE;

			else if ((offset + length == object_size) ||

			} else if ((offset + length == object_size)) {

				(obj_request->img_offset + length == img_end))

				opcode = CEPH_OSD_OP_TRUNCATE;

			} else {

				down_read(&rbd_dev->header_rwsem);

				img_end = rbd_dev->header.image_size;

				up_read(&rbd_dev->header_rwsem);



				if (obj_request->img_offset + length == img_end)

					opcode = CEPH_OSD_OP_TRUNCATE;

					opcode = CEPH_OSD_OP_TRUNCATE;

				else

				else

					opcode = CEPH_OSD_OP_ZERO;

					opcode = CEPH_OSD_OP_ZERO;

			}

		} else if (img_request_write_test(img_request)) {

		} else if (img_request_write_test(img_request)) {

			op_type = OBJ_OP_WRITE;

			op_type = OBJ_OP_WRITE;

			opcode = CEPH_OSD_OP_WRITE;

			opcode = CEPH_OSD_OP_WRITE;