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Commit c1c87c2b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

loop: make do_req_filebacked more robust 



Use a switch statement to iterate over the possible operations and
error out if it's an incorrect one.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent f0225cac

drivers/block/loop.c

+22 −33
Original line number Diff line number Diff line
@@ -510,14 +510,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 
	return 0;

}





static inline int lo_rw_simple(struct loop_device *lo,

		struct request *rq, loff_t pos, bool rw)

static int do_req_filebacked(struct loop_device *lo, struct request *rq)

{

	struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);



	if (cmd->use_aio)

		return lo_rw_aio(lo, cmd, pos, rw);

	loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;



	/*

	 * lo_write_simple and lo_read_simple should have been covered
@@ -528,37 +524,30 @@ static inline int lo_rw_simple(struct loop_device *lo, 
	 * of the req at one time. And direct read IO doesn't need to

	 * run flush_dcache_page().

	 */

	if (rw == WRITE)

		return lo_write_simple(lo, rq, pos);

	else

		return lo_read_simple(lo, rq, pos);

}



static int do_req_filebacked(struct loop_device *lo, struct request *rq)

{

	loff_t pos;

	int ret;



	pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;



	if (op_is_write(req_op(rq))) {

		if (req_op(rq) == REQ_OP_FLUSH)

			ret = lo_req_flush(lo, rq);

		else if (req_op(rq) == REQ_OP_DISCARD)

			ret = lo_discard(lo, rq, pos);

		else if (lo->transfer)

			ret = lo_write_transfer(lo, rq, pos);

	switch (req_op(rq)) {

	case REQ_OP_FLUSH:

		return lo_req_flush(lo, rq);

	case REQ_OP_DISCARD:

		return lo_discard(lo, rq, pos);

	case REQ_OP_WRITE:

		if (lo->transfer)

			return lo_write_transfer(lo, rq, pos);

		else if (cmd->use_aio)

			return lo_rw_aio(lo, cmd, pos, WRITE);

		else

			ret = lo_rw_simple(lo, rq, pos, WRITE);



	} else {

			return lo_write_simple(lo, rq, pos);

	case REQ_OP_READ:

		if (lo->transfer)

			ret = lo_read_transfer(lo, rq, pos);

			return lo_read_transfer(lo, rq, pos);

		else if (cmd->use_aio)

			return lo_rw_aio(lo, cmd, pos, READ);

		else

			ret = lo_rw_simple(lo, rq, pos, READ);

			return lo_read_simple(lo, rq, pos);

	default:

		WARN_ON_ONCE(1);

		return -EIO;

		break;

	}



	return ret;

}



struct switch_request {