block: flip iter directions in blk_rq_integrity_map_user()

JIRA: https://issues.redhat.com/browse/RHEL-102497

commit 43a67dd
Author: Caleb Sander Mateos <csander@purestorage.com>
Date:   Tue Jun 3 12:47:51 2025 -0600

    block: flip iter directions in blk_rq_integrity_map_user()

    blk_rq_integrity_map_user() creates the ubuf iter with ITER_DEST for
    write-direction operations and ITER_SOURCE for read-direction ones.
    This is backwards; writes use the user buffer as a source for metadata
    and reads use it as a destination. Switch to the rq_data_dir() helper,
    which maps writes to ITER_SOURCE (WRITE) and reads to ITER_DEST(READ).

    Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
    Fixes: fe8f4ca ("block: modify bio_integrity_map_user to accept iov_iter as argument")
    Link: https://lore.kernel.org/r/20250603184752.1185676-1-csander@purestorage.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

Author: Ming Lei

block/blk-integrity.c

@@ -117,13 +117,8 @@ int blk_rq_integrity_map_user(struct request *rq, void __user *ubuf,
 {
 	int ret;
 	struct iov_iter iter;
-	unsigned int direction;
 
-	if (op_is_write(req_op(rq)))
-		direction = ITER_DEST;
-	else
-		direction = ITER_SOURCE;
-	iov_iter_ubuf(&iter, direction, ubuf, bytes);
+	iov_iter_ubuf(&iter, rq_data_dir(rq), ubuf, bytes);
 	ret = bio_integrity_map_user(rq->bio, &iter);
 	if (ret)
 		return ret;