linux-kernel - [PATCH 4.20 062/117] CIFS: Fix credits calculations for reads with errors

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Date:   Tue, 29 Jan 2019 12:35:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pavel Shilovsky <pshilov@...rosoft.com>,
        Ronnie Sahlberg <lsahlber@...hat.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 4.20 062/117] CIFS: Fix credits calculations for reads with errors

4.20-stable review patch.  If anyone has any objections, please let me know.

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

From: Pavel Shilovsky <pshilov@...rosoft.com>

commit 8004c78c68e894e4fd5ac3c22cc22eb7dc24cabc upstream.

Currently we mark MID as malformed if we get an error from server
in a read response. This leads to not properly processing credits
in the readv callback. Fix this by marking such a response as
normal received response and process it appropriately.

Cc: <stable@...r.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@...rosoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@...hat.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/cifs/cifssmb.c |   35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1458,18 +1458,26 @@ cifs_discard_remaining_data(struct TCP_S
 }
 
 static int
-cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+__cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid,
+		     bool malformed)
 {
 	int length;
-	struct cifs_readdata *rdata = mid->callback_data;
 
 	length = cifs_discard_remaining_data(server);
-	dequeue_mid(mid, rdata->result);
+	dequeue_mid(mid, malformed);
 	mid->resp_buf = server->smallbuf;
 	server->smallbuf = NULL;
 	return length;
 }
 
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	struct cifs_readdata *rdata = mid->callback_data;
+
+	return  __cifs_readv_discard(server, mid, rdata->result);
+}
+
 int
 cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 {
@@ -1511,12 +1519,23 @@ cifs_readv_receive(struct TCP_Server_Inf
 		return -1;
 	}
 
+	/* set up first two iov for signature check and to get credits */
+	rdata->iov[0].iov_base = buf;
+	rdata->iov[0].iov_len = 4;
+	rdata->iov[1].iov_base = buf + 4;
+	rdata->iov[1].iov_len = server->total_read - 4;
+	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
+	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[1].iov_base, rdata->iov[1].iov_len);
+
 	/* Was the SMB read successful? */
 	rdata->result = server->ops->map_error(buf, false);
 	if (rdata->result != 0) {
 		cifs_dbg(FYI, "%s: server returned error %d\n",
 			 __func__, rdata->result);
-		return cifs_readv_discard(server, mid);
+		/* normal error on read response */
+		return __cifs_readv_discard(server, mid, false);
 	}
 
 	/* Is there enough to get to the rest of the READ_RSP header? */
@@ -1560,14 +1579,6 @@ cifs_readv_receive(struct TCP_Server_Inf
 		server->total_read += length;
 	}
 
-	/* set up first iov for signature check */
-	rdata->iov[0].iov_base = buf;
-	rdata->iov[0].iov_len = 4;
-	rdata->iov[1].iov_base = buf + 4;
-	rdata->iov[1].iov_len = server->total_read - 4;
-	cifs_dbg(FYI, "0: iov_base=%p iov_len=%u\n",
-		 rdata->iov[0].iov_base, server->total_read);
-
 	/* how much data is in the response? */
 #ifdef CONFIG_CIFS_SMB_DIRECT
 	use_rdma_mr = rdata->mr;