linux-kernel - [PATCH 5/5] cifs: Fix credit handling

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Message-ID: <20240823161209.434705-6-dhowells@redhat.com>
Date: Fri, 23 Aug 2024 17:12:06 +0100
From: David Howells <dhowells@...hat.com>
To: Christian Brauner <christian@...uner.io>
Cc: David Howells <dhowells@...hat.com>,
	Pankaj Raghav <p.raghav@...sung.com>,
	Jeff Layton <jlayton@...nel.org>,
	Matthew Wilcox <willy@...radead.org>,
	netfs@...ts.linux.dev,
	linux-afs@...ts.infradead.org,
	linux-cifs@...r.kernel.org,
	linux-nfs@...r.kernel.org,
	ceph-devel@...r.kernel.org,
	v9fs@...ts.linux.dev,
	linux-erofs@...ts.ozlabs.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>
Subject: [PATCH 5/5] cifs: Fix credit handling

Fix some bits of credit handling:

 (1) Use the ->actual_len value rather than the total subrequest length in
     smb2_adjust_credits() so that we don't trip the error message that we
     don't have sufficient credits allocated in a retry.

 (2) Set wdata->actual_len in writes as smb2_adjust_credits() now expects to
     see it set.

 (3) Reset the in_flight_check flag on a retry as we're doing a new read.

 (4) Add a missing credit resubmission trace.

Fixes: 82d55e76bf2f ("cifs: Fix lack of credit renegotiation on read retry")
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Steve French <sfrench@...ba.org>
cc: Paulo Alcantara <pc@...guebit.com>
cc: Jeff Layton <jlayton@...nel.org>
cc: linux-cifs@...r.kernel.org
cc: netfs@...ts.linux.dev
cc: linux-fsdevel@...r.kernel.org
---
 fs/smb/client/file.c    | 9 +++++++++
 fs/smb/client/smb2ops.c | 2 +-
 fs/smb/client/trace.h   | 1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 493c16e7c4ab..b94802438c62 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -111,6 +111,7 @@ static void cifs_issue_write(struct netfs_io_subrequest *subreq)
 		goto fail;
 	}
 
+	wdata->actual_len = wdata->subreq.len;
 	rc = adjust_credits(wdata->server, wdata, cifs_trace_rw_credits_issue_write_adjust);
 	if (rc)
 		goto fail;
@@ -227,6 +228,14 @@ static void cifs_req_issue_read(struct netfs_io_subrequest *subreq)
 						   &rdata->credits);
 		if (rc)
 			goto out;
+
+		rdata->credits.in_flight_check = 1;
+
+		trace_smb3_rw_credits(rdata->rreq->debug_id,
+				      rdata->subreq.debug_index,
+				      rdata->credits.value,
+				      server->credits, server->in_flight, 0,
+				      cifs_trace_rw_credits_read_resubmit);
 	}
 
 	if (req->cfile->invalidHandle) {
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 20e674990760..5090088ba727 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -301,7 +301,7 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
 		    unsigned int /*enum smb3_rw_credits_trace*/ trace)
 {
 	struct cifs_credits *credits = &subreq->credits;
-	int new_val = DIV_ROUND_UP(subreq->subreq.len, SMB2_MAX_BUFFER_SIZE);
+	int new_val = DIV_ROUND_UP(subreq->actual_len, SMB2_MAX_BUFFER_SIZE);
 	int scredits, in_flight;
 
 	if (!credits->value || credits->value == new_val)
diff --git a/fs/smb/client/trace.h b/fs/smb/client/trace.h
index 0f0c10c7ada7..8e9964001e2a 100644
--- a/fs/smb/client/trace.h
+++ b/fs/smb/client/trace.h
@@ -30,6 +30,7 @@
 	EM(cifs_trace_rw_credits_old_session,		"old-session") \
 	EM(cifs_trace_rw_credits_read_response_add,	"rd-resp-add") \
 	EM(cifs_trace_rw_credits_read_response_clear,	"rd-resp-clr") \
+	EM(cifs_trace_rw_credits_read_resubmit,		"rd-resubmit") \
 	EM(cifs_trace_rw_credits_read_submit,		"rd-submit  ") \
 	EM(cifs_trace_rw_credits_write_prepare,		"wr-prepare ") \
 	EM(cifs_trace_rw_credits_write_response_add,	"wr-resp-add") \