[PATCH 4.17 149/324] drbd: Fix drbd_request_prepare() discard handling

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@xxxxxxx>

[ Upstream commit fad2d4ef636654e926d374ef038f4cd4286661f6 ]

Fix the test that verifies whether bio_op(bio) represents a discard
or write zeroes operation. Compile-tested only.

Cc: Philipp Reisner <philipp.reisner@xxxxxxxxxx>
Cc: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
Fixes: 7435e9018f91 ("drbd: zero-out partial unaligned discards on local backend")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/block/drbd/drbd_req.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1244,8 +1244,8 @@ drbd_request_prepare(struct drbd_device
 	_drbd_start_io_acct(device, req);
 
 	/* process discards always from our submitter thread */
-	if ((bio_op(bio) & REQ_OP_WRITE_ZEROES) ||
-	    (bio_op(bio) & REQ_OP_DISCARD))
+	if (bio_op(bio) == REQ_OP_WRITE_ZEROES ||
+	    bio_op(bio) == REQ_OP_DISCARD)
 		goto queue_for_submitter_thread;
 
 	if (rw == WRITE && req->private_bio && req->i.size