[PATCH v2] nvme-tcp: fix request PDU size when header digest is enabled

[Christian Aurich Zanettini Martins <christian.aurichzm@gmail.com>]

Since commit 61b0ed3be81b ("nvme-tcp: parallelize I/O queue allocation
and startup") the I/O tag set is allocated before the I/O queues.
nvme_tcp_init_request() sizes the PDU with nvme_tcp_hdgst_len(queue),
but queue->hdr_digest is only set later by nvme_tcp_alloc_queue(), so
every I/O PDU is allocated without room for the header digest.

With hdr_digest enabled, the digest is then written 4 bytes past the
PDU, over the header of the next PDU in the page_frag cache, and the
target drops the connection on the first I/O:

  nvmet_tcp: unexpected pdu type 159
  nvmet: ctrl 1 fatal error occurred!

Queues that a later reconnect adds for the first time have the same
problem.

Set queue->hdr_digest when allocating the controller, together with
pf_cache_lock, so it is valid before any request is initialized.

Fixes: 61b0ed3be81b ("nvme-tcp: parallelize I/O queue allocation and startup")
Signed-off-by: Christian Aurich Zanettini Martins <christian.aurichzm@gmail.com>
---
Changes in v2:
- Set queue->hdr_digest when allocating the controller, next to the
  pf_cache_lock init, instead of reading the option in
  nvme_tcp_init_request() (Keith)

v1: https://lore.kernel.org/linux-nvme/20261026184621.29276-1-christian.aurichzm@gmail.com/

Based on nvme-7.4 (aaedcff90148); needs a504cd79b167 from there.

Tested in QEMU with nvmet-tcp over loopback and parallel I/O: with
hdr_digest the connection failed on the first I/O before the fix; after
it, no errors and the data matched, also with data_digest and with a
reconnect growing the queues from 2 to 4 (attr_qid_max).

 drivers/nvme/host/tcp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index f876375dffd2..2209586f3809 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1948,7 +1948,6 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid,
 		}
 	}
 
-	queue->hdr_digest = nctrl->opts->hdr_digest;
 	queue->data_digest = nctrl->opts->data_digest;
 
 	rcv_pdu_size = sizeof(struct nvme_tcp_rsp_pdu) +
@@ -3098,10 +3097,13 @@ static struct nvme_tcp_ctrl *nvme_tcp_alloc_ctrl(struct device *dev,
 	/*
 	 * The I/O tag set is allocated before the I/O queues, and initializing
 	 * its requests already allocates the PDUs from the page frag caches of
-	 * the queues, so initialize their locks here.
+	 * the queues, sized by their header digest setting, so set up the
+	 * locks and hdr_digest here.
 	 */
-	for (i = 0; i < ctrl->ctrl.queue_count; i++)
+	for (i = 0; i < ctrl->ctrl.queue_count; i++) {
 		mutex_init(&ctrl->queues[i].pf_cache_lock);
+		ctrl->queues[i].hdr_digest = opts->hdr_digest;
+	}
 
 	ctrl->net = get_net(current->nsproxy->net_ns);
 
-- 
2.43.0