cifs: commands that are retried should have replay flag set

[ Upstream commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e ]

MS-SMB2 states that the header flag SMB2_FLAGS_REPLAY_OPERATION
needs to be set when a command needs to be retried, so that
the server is aware that this is a replay for an operation that
appeared before.

This can be very important, for example, for state changing
operations and opens which get retried following a reconnect;
since the client maybe unaware of the status of the previous
open.

This is particularly important for multichannel scenario, since
disconnection of one connection does not mean that the session
is lost. The requests can be replayed on another channel.

This change also makes use of exponential back-off before replays
and also limits the number of retries to "retrans" mount option
value.

Also, this change does not modify the read/write codepath.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 27 insertions, 6 deletions

diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
index 1388ce5421a8..94df328a1965 100644
--- a/fs/smb/client/smb2inode.c
+++ b/fs/smb/client/smb2inode.c
@@ -92,6 +92,14 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	unsigned int size[2];
 	void *data[2];
 	int len;
+	int retries = 0, cur_sleep = 1;
+
+replay_again:
+	/* reinitialize for possible replay */
+	flags = 0;
+	oplock = SMB2_OPLOCK_LEVEL_NONE;
+	num_rqst = 0;
+	server = cifs_pick_channel(ses);
 
 	vars = kzalloc(sizeof(*vars), GFP_ATOMIC);
 	if (vars == NULL)
@@ -99,8 +107,6 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst = &vars->rqst[0];
 	rsp_iov = &vars->rsp_iov[0];
 
-	server = cifs_pick_channel(ses);
-
 	if (smb3_encryption_required(tcon))
 		flags |= CIFS_TRANSFORM_REQ;
 
@@ -435,15 +441,24 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	num_rqst++;
 
 	if (cfile) {
+		if (retries)
+			for (i = 1; i < num_rqst - 2; i++)
+				smb2_set_replay(server, &rqst[i]);
+
 		rc = compound_send_recv(xid, ses, server,
 					flags, num_rqst - 2,
 					&rqst[1], &resp_buftype[1],
 					&rsp_iov[1]);
-	} else
+	} else {
+		if (retries)
+			for (i = 0; i < num_rqst; i++)
+				smb2_set_replay(server, &rqst[i]);
+
 		rc = compound_send_recv(xid, ses, server,
 					flags, num_rqst,
 					rqst, resp_buftype,
 					rsp_iov);
+	}
 
 finished:
 	num_rqst = 0;
@@ -604,9 +619,6 @@ finished:
 	}
 	SMB2_close_free(&rqst[num_rqst]);
 
-	if (cfile)
-		cifsFileInfo_put(cfile);
-
 	num_cmds += 2;
 	if (out_iov && out_buftype) {
 		memcpy(out_iov, rsp_iov, num_cmds * sizeof(*out_iov));
@@ -616,7 +628,16 @@ finished:
 		for (i = 0; i < num_cmds; i++)
 			free_rsp_buf(resp_buftype[i], rsp_iov[i].iov_base);
 	}
+	num_cmds -= 2; /* correct num_cmds as there could be a retry */
 	kfree(vars);
+
+	if (is_replayable_error(rc) &&
+	    smb2_should_replay(tcon, &retries, &cur_sleep))
+		goto replay_again;
+
+	if (cfile)
+		cifsFileInfo_put(cfile);
+
 	return rc;
 }