linux-kernel - [Patch v4 20/22] CIFS: SMBD: Read correct returned data length for RDMA write (SMB read) I/O

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Date:   Sun,  1 Oct 2017 19:30:28 -0700
From:   Long Li <longli@...hange.microsoft.com>
To:     Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
        Tom Talpey <ttalpey@...rosoft.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>
Cc:     Long Li <longli@...rosoft.com>
Subject: [Patch v4 20/22] CIFS: SMBD: Read correct returned data length for RDMA write (SMB read) I/O

From: Long Li <longli@...rosoft.com>

This patch is for preparing upper layer for doing SMB read via RDMA write.

When RDMA write is used for SMB read, the returned data length is in
DataRemaining in the response packet. Reading it properly by adding a
parameter to specifiy where the returned data length is.

Signed-off-by: Long Li <longli@...rosoft.com>
---
 fs/cifs/cifsglob.h | 10 ++++++++--
 fs/cifs/cifssmb.c  |  4 ++--
 fs/cifs/smb1ops.c  |  2 +-
 fs/cifs/smb2ops.c  |  8 ++++++--
 4 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index bcb6df1..f851b50 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -228,8 +228,14 @@ struct smb_version_operations {
 	__u64 (*get_next_mid)(struct TCP_Server_Info *);
 	/* data offset from read response message */
 	unsigned int (*read_data_offset)(char *);
-	/* data length from read response message */
-	unsigned int (*read_data_length)(char *);
+	/*
+	 * Data length from read response message
+	 * When in_remaining is true, the returned data length is in
+	 * message field DataRemaining for out-of-band data read (e.g through
+	 * Memory Registration RDMA write in SMBD).
+	 * Otherwise, the returned data length is in message field DataLength.
+	 */
+	unsigned int (*read_data_length)(char *, bool in_remaining);
 	/* map smb to linux error */
 	int (*map_error)(char *, bool);
 	/* find mid corresponding to the response message */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 0e29ecf..b9410e1 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1531,8 +1531,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 		 rdata->iov[0].iov_base, server->total_read);
 
 	/* how much data is in the response? */
-	data_len = server->ops->read_data_length(buf);
-	if (data_offset + data_len > buflen) {
+	data_len = server->ops->read_data_length(buf, rdata->mr);
+	if (!rdata->mr && (data_offset + data_len > buflen)) {
 		/* data_len is corrupt -- discard frame */
 		rdata->result = -EIO;
 		return cifs_readv_discard(server, mid);
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index a723df3..27a8280 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -87,7 +87,7 @@ cifs_read_data_offset(char *buf)
 }
 
 static unsigned int
-cifs_read_data_length(char *buf)
+cifs_read_data_length(char *buf, bool in_remaining)
 {
 	READ_RSP *rsp = (READ_RSP *)buf;
 	return (le16_to_cpu(rsp->DataLengthHigh) << 16) +
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 7ad35d6..a765877 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -935,9 +935,13 @@ smb2_read_data_offset(char *buf)
 }
 
 static unsigned int
-smb2_read_data_length(char *buf)
+smb2_read_data_length(char *buf, bool in_remaining)
 {
 	struct smb2_read_rsp *rsp = (struct smb2_read_rsp *)buf;
+
+	if (in_remaining)
+		return le32_to_cpu(rsp->DataRemaining);
+
 	return le32_to_cpu(rsp->DataLength);
 }
 
@@ -2446,7 +2450,7 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 	}
 
 	data_offset = server->ops->read_data_offset(buf) + 4;
-	data_len = server->ops->read_data_length(buf);
+	data_len = server->ops->read_data_length(buf, rdata->mr);
 
 	if (data_offset < server->vals->read_rsp_size) {
 		/*
-- 
2.7.4