ksmbd: smbd: fix dma mapping error in smb_direct_post_send_data

mainline inclusion
from mainline-5.15-rc1
commit 72d6cbb5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G
CVE: NA

Reference: https://git.kernel.org/torvalds/linux/c/72d6cbb533d4

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

Becase smb direct header is mapped and msg->num_sge
already is incremented, the decrement should be
removed from the condition.
Signed-off-by: NHyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: NNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>

fs/ksmbd/transport_rdma.c

@@ -1168,7 +1168,7 @@ static int smb_direct_post_send_data(struct smb_direct_transport *t,
 			pr_err("failed to map buffer\n");
 			ret = -ENOMEM;
 			goto err;
-		} else if (sg_cnt + msg->num_sge > SMB_DIRECT_MAX_SEND_SGES - 1) {
+		} else if (sg_cnt + msg->num_sge > SMB_DIRECT_MAX_SEND_SGES) {
 			pr_err("buffer not fitted into sges\n");
 			ret = -E2BIG;
 			ib_dma_unmap_sg(t->cm_id->device, sg, sg_cnt,