From 164cacd0ba380604253b96dc312c85366147e3f7 Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Thu, 5 Feb 2026 17:14:15 +0100 Subject: [PATCH] smb: server: correct value for smb_direct_max_fragmented_recv_size We should make it clear that we use this strange value instead of hiding it in same code flow. Note this value is mainly ignored currently, as we do the calculation again with the negotiated max_recv_size in smb_direct_prepare(). So this is only a cosmetic change in order to avoid confusion. In future we may change the logic and adjust the number of recv buffers instead of the max_fragmented_recv_size. Acked-by: Namjae Jeon Cc: Steve French Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Signed-off-by: Steve French --- fs/smb/server/transport_rdma.c | 42 ++++++++++++++++++++++++++++++++-- 1 file changed, 40 insertions(+), 2 deletions(-) diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c index 188f6c9c07d6..fb36fb9d5214 100644 --- a/fs/smb/server/transport_rdma.c +++ b/fs/smb/server/transport_rdma.c @@ -70,8 +70,23 @@ static int smb_direct_send_credit_target = 255; /* The maximum single message size can be sent to remote peer */ static int smb_direct_max_send_size = 1364; -/* The maximum fragmented upper-layer payload receive size supported */ -static int smb_direct_max_fragmented_recv_size = 1024 * 1024; +/* + * The maximum fragmented upper-layer payload receive size supported + * + * Assume max_payload_per_credit is + * smb_direct_receive_credit_max - 24 = 1340 + * + * The maximum number would be + * smb_direct_receive_credit_max * max_payload_per_credit + * + * 1340 * 255 = 341700 (0x536C4) + * + * The minimum value from the spec is 131072 (0x20000) + * + * For now we use the logic we used before: + * (1364 * 255) / 2 = 173910 (0x2A756) + */ +static int smb_direct_max_fragmented_recv_size = (1364 * 255) / 2; /* The maximum single-message size which can be received */ static int smb_direct_max_receive_size = 1364; @@ -2531,6 +2546,29 @@ static int smb_direct_prepare(struct ksmbd_transport *t) le32_to_cpu(req->max_receive_size)); sp->max_fragmented_send_size = le32_to_cpu(req->max_fragmented_size); + /* + * The maximum fragmented upper-layer payload receive size supported + * + * Assume max_payload_per_credit is + * smb_direct_receive_credit_max - 24 = 1340 + * + * The maximum number would be + * smb_direct_receive_credit_max * max_payload_per_credit + * + * 1340 * 255 = 341700 (0x536C4) + * + * The minimum value from the spec is 131072 (0x20000) + * + * For now we use the logic we used before: + * (1364 * 255) / 2 = 173910 (0x2A756) + * + * We need to adjust this here in case the peer + * lowered sp->max_recv_size. + * + * TODO: instead of adjusting max_fragmented_recv_size + * we should adjust the number of available buffers, + * but for now we keep the current logic. + */ sp->max_fragmented_recv_size = (sp->recv_credit_max * sp->max_recv_size) / 2; sc->recv_io.credits.target = le16_to_cpu(req->credits_requested); -- 2.47.3