[PATCH 4.4 120/210] brd: Fix discard request processing

[Greg Kroah-Hartman]

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

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

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

commit 5e4298be45e83ecdffaabb370eea9396889b07f1 upstream.

Avoid that discard requests with size => PAGE_SIZE fail with
-EIO. Refuse discard requests if the discard size is not a
multiple of the page size.

Fixes: 2dbe54957636 ("brd: Refuse improperly aligned discard requests")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Robert Elliot <elliott@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/block/brd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -338,7 +338,7 @@ static blk_qc_t brd_make_request(struct
 
 	if (unlikely(bio->bi_rw & REQ_DISCARD)) {
 		if (sector & ((PAGE_SIZE >> SECTOR_SHIFT) - 1) ||
-		    bio->bi_iter.bi_size & PAGE_MASK)
+		    bio->bi_iter.bi_size & ~PAGE_MASK)
 			goto io_error;
 		discard_from_brd(brd, sector, bio->bi_iter.bi_size);
 		goto out;