cifs: multichannel: move channel selection above transport layer

Move the channel (TCP_Server_Info*) selection from the tranport
layer to higher in the call stack so that:

- credit handling is done with the server that will actually be used
  to send.
  * ->wait_mtu_credit
  * ->set_credits / set_credits
  * ->add_credits / add_credits
  * add_credits_and_wake_if

- potential reconnection (smb2_reconnect) done when initializing a
  request is checked and done with the server that will actually be
  used to send.

To do this:

- remove the cifs_pick_channel() call out of compound_send_recv()

- select channel and pass it down by adding a cifs_pick_channel(ses)
  call in:
  - smb311_posix_mkdir
  - SMB2_open
  - SMB2_ioctl
  - __SMB2_close
  - query_info
  - SMB2_change_notify
  - SMB2_flush
  - smb2_async_readv  (if none provided in context param)
  - SMB2_read         (if none provided in context param)
  - smb2_async_writev (if none provided in context param)
  - SMB2_write        (if none provided in context param)
  - SMB2_query_directory
  - send_set_info
  - SMB2_oplock_break
  - SMB311_posix_qfs_info
  - SMB2_QFS_info
  - SMB2_QFS_attr
  - smb2_lockv
  - SMB2_lease_break
    - smb2_compound_op
  - smb2_set_ea
  - smb2_ioctl_query_info
  - smb2_query_dir_first
  - smb2_query_info_comound
  - smb2_query_symlink
  - cifs_writepages
  - cifs_write_from_iter
  - cifs_send_async_read
  - cifs_read
  - cifs_readpages

- add TCP_Server_Info *server param argument to:
  - cifs_send_recv
  - compound_send_recv
  - SMB2_open_init
  - SMB2_query_info_init
  - SMB2_set_info_init
  - SMB2_close_init
  - SMB2_ioctl_init
  - smb2_iotcl_req_init
  - SMB2_query_directory_init
  - SMB2_notify_init
  - SMB2_flush_init
  - build_qfs_info_req
  - smb2_hdr_assemble
  - smb2_reconnect
  - fill_small_buf
  - smb2_plain_req_init
  - __smb2_plain_req_init

The read/write codepath is different than the rest as it is using
pages, io iterators and async calls. To deal with those we add a
server pointer in the cifs_writedata/cifs_readdata/cifs_io_parms
context struct and set it in:

- cifs_writepages      (wdata)
- cifs_write_from_iter (wdata)
- cifs_readpages       (rdata)
- cifs_send_async_read (rdata)

The [rw]data->server pointer is eventually copied to
cifs_io_parms->server to pass it down to SMB2_read/SMB2_write.
If SMB2_read/SMB2_write is called from a different place that doesn't
set the server field it will pick a channel.

Some places do not pick a channel and just use ses->server or
cifs_ses_server(ses). All cifs_ses_server(ses) calls are in codepaths
involving negprot/sess.setup.

- SMB2_negotiate         (binding channel)
- SMB2_sess_alloc_buffer (binding channel)
- SMB2_echo              (uses provided one)
- SMB2_logoff            (uses master)
- SMB2_tdis              (uses master)

(list not exhaustive)

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

9 files changed, 356 insertions, 198 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 4d261fd78fcb..c0cbbd0bbb1d 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1335,6 +1335,7 @@ struct cifs_io_parms {
 	__u64 offset;
 	unsigned int length;
 	struct cifs_tcon *tcon;
+	struct TCP_Server_Info *server;
 };
 
 struct cifs_aio_ctx {
@@ -1382,6 +1383,7 @@ struct cifs_readdata {
 				struct cifs_readdata *rdata,
 				struct iov_iter *iter);
 	struct kvec			iov[2];
+	struct TCP_Server_Info		*server;
 #ifdef CONFIG_CIFS_SMB_DIRECT
 	struct smbd_mr			*mr;
 #endif
@@ -1408,6 +1410,7 @@ struct cifs_writedata {
 	pid_t				pid;
 	unsigned int			bytes;
 	int				result;
+	struct TCP_Server_Info		*server;
 #ifdef CONFIG_CIFS_SMB_DIRECT
 	struct smbd_mr			*mr;
 #endif
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 9767f9b5d315..a25a46237f9f 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -98,9 +98,11 @@ extern int cifs_call_async(struct TCP_Server_Info *server,
 			const struct cifs_credits *exist_credits);
 extern struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses);
 extern int cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
+			  struct TCP_Server_Info *server,
 			  struct smb_rqst *rqst, int *resp_buf_type,
 			  const int flags, struct kvec *resp_iov);
 extern int compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
+			      struct TCP_Server_Info *server,
 			      const int flags, const int num_rqst,
 			      struct smb_rqst *rqst, int *resp_buf_type,
 			      struct kvec *resp_iov);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index de130f3aa452..2ca9b387d216 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2292,8 +2292,6 @@ wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
 		 struct address_space *mapping, struct writeback_control *wbc)
 {
 	int rc;
-	struct TCP_Server_Info *server =
-				tlink_tcon(wdata->cfile->tlink)->ses->server;
 
 	wdata->sync_mode = wbc->sync_mode;
 	wdata->nr_pages = nr_pages;
@@ -2305,14 +2303,15 @@ wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
 	wdata->bytes = ((nr_pages - 1) * PAGE_SIZE) + wdata->tailsz;
 	wdata->pid = wdata->cfile->pid;
 
-	rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+	rc = adjust_credits(wdata->server, &wdata->credits, wdata->bytes);
 	if (rc)
 		return rc;
 
 	if (wdata->cfile->invalidHandle)
 		rc = -EAGAIN;
 	else
-		rc = server->ops->async_writev(wdata, cifs_writedata_release);
+		rc = wdata->server->ops->async_writev(wdata,
+						      cifs_writedata_release);
 
 	return rc;
 }
@@ -2349,7 +2348,8 @@ static int cifs_writepages(struct address_space *mapping,
 			range_whole = true;
 		scanned = true;
 	}
-	server = cifs_sb_master_tcon(cifs_sb)->ses->server;
+	server = cifs_pick_channel(cifs_sb_master_tcon(cifs_sb)->ses);
+
 retry:
 	while (!done && index <= end) {
 		unsigned int i, nr_pages, found_pages, wsize;
@@ -2403,6 +2403,7 @@ retry:
 
 		wdata->credits = credits_on_stack;
 		wdata->cfile = cfile;
+		wdata->server = server;
 		cfile = NULL;
 
 		if (!wdata->cfile) {
@@ -2806,8 +2807,7 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 	unsigned int wsize;
 	struct cifs_credits credits;
 	int rc;
-	struct TCP_Server_Info *server =
-		tlink_tcon(wdata->cfile->tlink)->ses->server;
+	struct TCP_Server_Info *server = wdata->server;
 
 	do {
 		if (wdata->cfile->invalidHandle) {
@@ -2893,7 +2893,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 	else
 		pid = current->tgid;
 
-	server = tlink_tcon(open_file->tlink)->ses->server;
+	server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);
 	xid = get_xid();
 
 	do {
@@ -2997,6 +2997,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 		wdata->nr_pages = nr_pages;
 		wdata->offset = (__u64)offset;
 		wdata->cfile = cifsFileInfo_get(open_file);
+		wdata->server = server;
 		wdata->pid = pid;
 		wdata->bytes = cur_len;
 		wdata->pagesz = PAGE_SIZE;
@@ -3538,8 +3539,10 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
 	unsigned int rsize;
 	struct cifs_credits credits;
 	int rc;
-	struct TCP_Server_Info *server =
-		tlink_tcon(rdata->cfile->tlink)->ses->server;
+	struct TCP_Server_Info *server;
+
+	/* XXX: should we pick a new channel here? */
+	server = rdata->server;
 
 	do {
 		if (rdata->cfile->invalidHandle) {
@@ -3618,7 +3621,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 	size_t start;
 	struct iov_iter direct_iov = ctx->iter;
 
-	server = tlink_tcon(open_file->tlink)->ses->server;
+	server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);
 
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
 		pid = open_file->pid;
@@ -3702,6 +3705,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 			rdata->tailsz = PAGE_SIZE;
 		}
 
+		rdata->server = server;
 		rdata->cfile = cifsFileInfo_get(open_file);
 		rdata->nr_pages = npages;
 		rdata->offset = offset;
@@ -4031,7 +4035,7 @@ cifs_read(struct file *file, char *read_data, size_t read_size, loff_t *offset)
 	}
 	open_file = file->private_data;
 	tcon = tlink_tcon(open_file->tlink);
-	server = tcon->ses->server;
+	server = cifs_pick_channel(tcon->ses);
 
 	if (!server->ops->sync_read) {
 		free_xid(xid);
@@ -4070,6 +4074,7 @@ cifs_read(struct file *file, char *read_data, size_t read_size, loff_t *offset)
 			io_parms.tcon = tcon;
 			io_parms.offset = *offset;
 			io_parms.length = current_read_size;
+			io_parms.server = server;
 			rc = server->ops->sync_read(xid, &open_file->fid, &io_parms,
 						    &bytes_read, &cur_offset,
 						    &buf_type);
@@ -4372,7 +4377,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 		pid = current->tgid;
 
 	rc = 0;
-	server = tlink_tcon(open_file->tlink)->ses->server;
+	server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);
 
 	cifs_dbg(FYI, "%s: file=%p mapping=%p num_pages=%u\n",
 		 __func__, file, mapping, num_pages);
@@ -4443,6 +4448,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 		}
 
 		rdata->cfile = cifsFileInfo_get(open_file);
+		rdata->server = server;
 		rdata->mapping = mapping;
 		rdata->offset = offset;
 		rdata->bytes = bytes;
diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 2072458e6e24..c381d2d03ef6 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -450,7 +450,7 @@ smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 	int rc;
 	struct cifs_fid fid;
 	struct cifs_open_parms oparms;
-	struct cifs_io_parms io_parms;
+	struct cifs_io_parms io_parms = {0};
 	__le16 *utf16_path;
 	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 	struct kvec iov[2];
diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index fa86c78384c3..0a116fc490a9 100644
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -74,6 +74,7 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 	struct cifs_fid fid;
 	struct cifs_ses *ses = tcon->ses;
+	struct TCP_Server_Info *server;
 	int num_rqst = 0;
 	int resp_buftype[3];
 	struct smb2_query_info_rsp *qi_rsp = NULL;
@@ -89,6 +90,8 @@ 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;
 
@@ -115,7 +118,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rqst[num_rqst].rq_iov = &vars->open_iov[0];
 	rqst[num_rqst].rq_nvec = SMB2_CREATE_IOV_SIZE;
-	rc = SMB2_open_init(tcon, &rqst[num_rqst], &oplock, &vars->oparms,
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[num_rqst], &oplock, &vars->oparms,
 			    utf16_path);
 	kfree(utf16_path);
 	if (rc)
@@ -133,7 +137,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		rqst[num_rqst].rq_nvec = 1;
 
 		if (cfile)
-			rc = SMB2_query_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_query_info_init(tcon, server,
+				&rqst[num_rqst],
 				cfile->fid.persistent_fid,
 				cfile->fid.volatile_fid,
 				FILE_ALL_INFORMATION,
@@ -141,10 +146,11 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 				sizeof(struct smb2_file_all_info) +
 					  PATH_MAX * 2, 0, NULL);
 		else {
-			rc = SMB2_query_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_query_info_init(tcon, server,
+				&rqst[num_rqst],
 				COMPOUND_FID,
 				COMPOUND_FID,
-				 FILE_ALL_INFORMATION,
+				FILE_ALL_INFORMATION,
 				SMB2_O_INFO_FILE, 0,
 				sizeof(struct smb2_file_all_info) +
 					  PATH_MAX * 2, 0, NULL);
@@ -177,7 +183,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		size[0] = 1; /* sizeof __u8 See MS-FSCC section 2.4.11 */
 		data[0] = &delete_pending[0];
 
-		rc = SMB2_set_info_init(tcon, &rqst[num_rqst], COMPOUND_FID,
+		rc = SMB2_set_info_init(tcon, server,
+					&rqst[num_rqst], COMPOUND_FID,
 					COMPOUND_FID, current->tgid,
 					FILE_DISPOSITION_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
@@ -194,7 +201,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		size[0] = 8; /* sizeof __le64 */
 		data[0] = ptr;
 
-		rc = SMB2_set_info_init(tcon, &rqst[num_rqst], COMPOUND_FID,
+		rc = SMB2_set_info_init(tcon, server,
+					&rqst[num_rqst], COMPOUND_FID,
 					COMPOUND_FID, current->tgid,
 					FILE_END_OF_FILE_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
@@ -213,13 +221,15 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		data[0] = ptr;
 
 		if (cfile)
-			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_set_info_init(tcon, server,
+				&rqst[num_rqst],
 				cfile->fid.persistent_fid,
 				cfile->fid.volatile_fid, current->tgid,
 				FILE_BASIC_INFORMATION,
 				SMB2_O_INFO_FILE, 0, data, size);
 		else {
-			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_set_info_init(tcon, server,
+				&rqst[num_rqst],
 				COMPOUND_FID,
 				COMPOUND_FID, current->tgid,
 				FILE_BASIC_INFORMATION,
@@ -253,13 +263,15 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		data[1] = (__le16 *)ptr;
 
 		if (cfile)
-			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_set_info_init(tcon, server,
+						&rqst[num_rqst],
 						cfile->fid.persistent_fid,
 						cfile->fid.volatile_fid,
 					current->tgid, FILE_RENAME_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
 		else {
-			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+			rc = SMB2_set_info_init(tcon, server,
+					&rqst[num_rqst],
 					COMPOUND_FID, COMPOUND_FID,
 					current->tgid, FILE_RENAME_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
@@ -289,7 +301,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		size[1] = len + 2 /* null */;
 		data[1] = (__le16 *)ptr;
 
-		rc = SMB2_set_info_init(tcon, &rqst[num_rqst], COMPOUND_FID,
+		rc = SMB2_set_info_init(tcon, server,
+					&rqst[num_rqst], COMPOUND_FID,
 					COMPOUND_FID, current->tgid,
 					FILE_LINK_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
@@ -312,7 +325,8 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	/* Close */
 	rqst[num_rqst].rq_iov = &vars->close_iov[0];
 	rqst[num_rqst].rq_nvec = 1;
-	rc = SMB2_close_init(tcon, &rqst[num_rqst], COMPOUND_FID,
+	rc = SMB2_close_init(tcon, server,
+			     &rqst[num_rqst], COMPOUND_FID,
 			     COMPOUND_FID, false);
 	smb2_set_related(&rqst[num_rqst]);
 	if (rc)
@@ -323,11 +337,13 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	if (cfile) {
 		cifsFileInfo_put(cfile);
 		cfile = NULL;
-		rc = compound_send_recv(xid, ses, flags, num_rqst - 2,
+		rc = compound_send_recv(xid, ses, server,
+					flags, num_rqst - 2,
 					&rqst[1], &resp_buftype[1],
 					&rsp_iov[1]);
 	} else
-		rc = compound_send_recv(xid, ses, flags, num_rqst,
+		rc = compound_send_recv(xid, ses, server,
+					flags, num_rqst,
 					rqst, resp_buftype,
 					rsp_iov);
 
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 49c5c80f5d36..e97eb0050a0e 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -708,7 +708,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = pfid;
 	oparms.reconnect = false;
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, &utf16_path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, &utf16_path);
 	if (rc)
 		goto oshr_free;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -717,7 +718,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 	rqst[1].rq_iov = qi_iov;
 	rqst[1].rq_nvec = 1;
 
-	rc = SMB2_query_info_init(tcon, &rqst[1], COMPOUND_FID,
+	rc = SMB2_query_info_init(tcon, server,
+				  &rqst[1], COMPOUND_FID,
 				  COMPOUND_FID, FILE_ALL_INFORMATION,
 				  SMB2_O_INFO_FILE, 0,
 				  sizeof(struct smb2_file_all_info) +
@@ -727,7 +729,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 
 	smb2_set_related(&rqst[1]);
 
-	rc = compound_send_recv(xid, ses, flags, 2, rqst,
+	rc = compound_send_recv(xid, ses, server,
+				flags, 2, rqst,
 				resp_buftype, rsp_iov);
 	mutex_lock(&tcon->crfid.fid_mutex);
 
@@ -1102,6 +1105,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	    struct cifs_sb_info *cifs_sb)
 {
 	struct cifs_ses *ses = tcon->ses;
+	struct TCP_Server_Info *server = cifs_pick_channel(ses);
 	__le16 *utf16_path = NULL;
 	int ea_name_len = strlen(ea_name);
 	int flags = 0;
@@ -1190,7 +1194,8 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = &fid;
 	oparms.reconnect = false;
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, utf16_path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto sea_exit;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -1216,7 +1221,8 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	size[0] = len;
 	data[0] = ea;
 
-	rc = SMB2_set_info_init(tcon, &rqst[1], COMPOUND_FID,
+	rc = SMB2_set_info_init(tcon, server,
+				&rqst[1], COMPOUND_FID,
 				COMPOUND_FID, current->tgid,
 				FILE_FULL_EA_INFORMATION,
 				SMB2_O_INFO_FILE, 0, data, size);
@@ -1228,10 +1234,12 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	memset(&close_iov, 0, sizeof(close_iov));
 	rqst[2].rq_iov = close_iov;
 	rqst[2].rq_nvec = 1;
-	rc = SMB2_close_init(tcon, &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
+	rc = SMB2_close_init(tcon, server,
+			     &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
 	smb2_set_related(&rqst[2]);
 
-	rc = compound_send_recv(xid, ses, flags, 3, rqst,
+	rc = compound_send_recv(xid, ses, server,
+				flags, 3, rqst,
 				resp_buftype, rsp_iov);
 	/* no need to bump num_remote_opens because handle immediately closed */
 
@@ -1473,6 +1481,7 @@ smb2_ioctl_query_info(const unsigned int xid,
 	struct smb_rqst *rqst;
 	struct kvec *rsp_iov;
 	struct cifs_ses *ses = tcon->ses;
+	struct TCP_Server_Info *server = cifs_pick_channel(ses);
 	char __user *arg = (char __user *)p;
 	struct smb_query_info qi;
 	struct smb_query_info __user *pqi;
@@ -1505,7 +1514,7 @@ smb2_ioctl_query_info(const unsigned int xid,
 		return -EINVAL;
 	}
 
-	if (!ses || !(ses->server)) {
+	if (!ses || !server) {
 		kfree(vars);
 		return -EIO;
 	}
@@ -1552,7 +1561,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 		oparms.desired_access = FILE_READ_ATTRIBUTES | READ_CONTROL;
 	}
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, path);
 	if (rc)
 		goto iqinf_exit;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -1566,7 +1576,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 			rqst[1].rq_iov = &vars->io_iov[0];
 			rqst[1].rq_nvec = SMB2_IOCTL_IOV_SIZE;
 
-			rc = SMB2_ioctl_init(tcon, &rqst[1],
+			rc = SMB2_ioctl_init(tcon, server,
+					     &rqst[1],
 					     COMPOUND_FID, COMPOUND_FID,
 					     qi.info_type, true, buffer,
 					     qi.output_buffer_length,
@@ -1585,7 +1596,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 			size[0] = 8;
 			data[0] = buffer;
 
-			rc = SMB2_set_info_init(tcon, &rqst[1],
+			rc = SMB2_set_info_init(tcon, server,
+					&rqst[1],
 					COMPOUND_FID, COMPOUND_FID,
 					current->tgid,
 					FILE_END_OF_FILE_INFORMATION,
@@ -1595,7 +1607,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 		rqst[1].rq_iov = &vars->qi_iov[0];
 		rqst[1].rq_nvec = 1;
 
-		rc = SMB2_query_info_init(tcon, &rqst[1], COMPOUND_FID,
+		rc = SMB2_query_info_init(tcon, server,
+				  &rqst[1], COMPOUND_FID,
 				  COMPOUND_FID, qi.file_info_class,
 				  qi.info_type, qi.additional_information,
 				  qi.input_buffer_length,
@@ -1615,12 +1628,14 @@ smb2_ioctl_query_info(const unsigned int xid,
 	rqst[2].rq_iov = &vars->close_iov[0];
 	rqst[2].rq_nvec = 1;
 
-	rc = SMB2_close_init(tcon, &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
+	rc = SMB2_close_init(tcon, server,
+			     &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
 	if (rc)
 		goto iqinf_exit;
 	smb2_set_related(&rqst[2]);
 
-	rc = compound_send_recv(xid, ses, flags, 3, rqst,
+	rc = compound_send_recv(xid, ses, server,
+				flags, 3, rqst,
 				resp_buftype, rsp_iov);
 	if (rc)
 		goto iqinf_exit;
@@ -2172,6 +2187,7 @@ smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 	struct cifs_open_parms oparms;
 	struct smb2_query_directory_rsp *qd_rsp = NULL;
 	struct smb2_create_rsp *op_rsp = NULL;
+	struct TCP_Server_Info *server = cifs_pick_channel(tcon->ses);
 
 	utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
 	if (!utf16_path)
@@ -2196,7 +2212,8 @@ smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = fid;
 	oparms.reconnect = false;
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, utf16_path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto qdf_free;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -2209,7 +2226,8 @@ smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst[1].rq_iov = qd_iov;
 	rqst[1].rq_nvec = SMB2_QUERY_DIRECTORY_IOV_SIZE;
 
-	rc = SMB2_query_directory_init(xid, tcon, &rqst[1],
+	rc = SMB2_query_directory_init(xid, tcon, server,
+				       &rqst[1],
 				       COMPOUND_FID, COMPOUND_FID,
 				       0, srch_inf->info_level);
 	if (rc)
@@ -2217,7 +2235,8 @@ smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 
 	smb2_set_related(&rqst[1]);
 
-	rc = compound_send_recv(xid, tcon->ses, flags, 2, rqst,
+	rc = compound_send_recv(xid, tcon->ses, server,
+				flags, 2, rqst,
 				resp_buftype, rsp_iov);
 
 	/* If the open failed there is nothing to do */
@@ -2422,6 +2441,7 @@ smb2_query_info_compound(const unsigned int xid, struct cifs_tcon *tcon,
 			 struct cifs_sb_info *cifs_sb)
 {
 	struct cifs_ses *ses = tcon->ses;
+	struct TCP_Server_Info *server = cifs_pick_channel(ses);
 	int flags = 0;
 	struct smb_rqst rqst[3];
 	int resp_buftype[3];
@@ -2452,7 +2472,8 @@ smb2_query_info_compound(const unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = &fid;
 	oparms.reconnect = false;
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, utf16_path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto qic_exit;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -2461,7 +2482,8 @@ smb2_query_info_compound(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst[1].rq_iov = qi_iov;
 	rqst[1].rq_nvec = 1;
 
-	rc = SMB2_query_info_init(tcon, &rqst[1], COMPOUND_FID, COMPOUND_FID,
+	rc = SMB2_query_info_init(tcon, server,
+				  &rqst[1], COMPOUND_FID, COMPOUND_FID,
 				  class, type, 0,
 				  output_len, 0,
 				  NULL);
@@ -2474,12 +2496,14 @@ smb2_query_info_compound(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst[2].rq_iov = close_iov;
 	rqst[2].rq_nvec = 1;
 
-	rc = SMB2_close_init(tcon, &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
+	rc = SMB2_close_init(tcon, server,
+			     &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
 	if (rc)
 		goto qic_exit;
 	smb2_set_related(&rqst[2]);
 
-	rc = compound_send_recv(xid, ses, flags, 3, rqst,
+	rc = compound_send_recv(xid, ses, server,
+				flags, 3, rqst,
 				resp_buftype, rsp_iov);
 	if (rc) {
 		free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
@@ -2811,6 +2835,7 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	struct kvec err_iov = {NULL, 0};
 	struct smb2_err_rsp *err_buf = NULL;
 	struct smb2_symlink_err_rsp *symlink;
+	struct TCP_Server_Info *server = cifs_pick_channel(tcon->ses);
 	unsigned int sub_len;
 	unsigned int sub_offset;
 	unsigned int print_len;
@@ -2856,7 +2881,8 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = &fid;
 	oparms.reconnect = false;
 
-	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, utf16_path);
+	rc = SMB2_open_init(tcon, server,
+			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto querty_exit;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -2867,7 +2893,8 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst[1].rq_iov = io_iov;
 	rqst[1].rq_nvec = SMB2_IOCTL_IOV_SIZE;
 
-	rc = SMB2_ioctl_init(tcon, &rqst[1], fid.persistent_fid,
+	rc = SMB2_ioctl_init(tcon, server,
+			     &rqst[1], fid.persistent_fid,
 			     fid.volatile_fid, FSCTL_GET_REPARSE_POINT,
 			     true /* is_fctl */, NULL, 0,
 			     CIFSMaxBufSize -
@@ -2885,13 +2912,15 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	rqst[2].rq_iov = close_iov;
 	rqst[2].rq_nvec = 1;
 
-	rc = SMB2_close_init(tcon, &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
+	rc = SMB2_close_init(tcon, server,
+			     &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
 	if (rc)
 		goto querty_exit;
 
 	smb2_set_related(&rqst[2]);
 
-	rc = compound_send_recv(xid, tcon->ses, flags, 3, rqst,
+	rc = compound_send_recv(xid, tcon->ses, server,
+				flags, 3, rqst,
 				resp_buftype, rsp_iov);
 
 	create_rsp = rsp_iov[0].iov_base;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 12de0af12f75..fe5a8452b213 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -98,14 +98,13 @@ int smb3_encryption_required(const struct cifs_tcon *tcon)
 
 static void
 smb2_hdr_assemble(struct smb2_sync_hdr *shdr, __le16 smb2_cmd,
-		  const struct cifs_tcon *tcon)
+		  const struct cifs_tcon *tcon,
+		  struct TCP_Server_Info *server)
 {
 	shdr->ProtocolId = SMB2_PROTO_NUMBER;
 	shdr->StructureSize = cpu_to_le16(64);
 	shdr->Command = smb2_cmd;
-	if (tcon && tcon->ses && tcon->ses->server) {
-		struct TCP_Server_Info *server = tcon->ses->server;
-
+	if (server) {
 		spin_lock(&server->req_lock);
 		/* Request up to 10 credits but don't go over the limit. */
 		if (server->credits >= server->max_credits)
@@ -125,8 +124,7 @@ smb2_hdr_assemble(struct smb2_sync_hdr *shdr, __le16 smb2_cmd,
 
 	/* GLOBAL_CAP_LARGE_MTU will only be set if dialect > SMB2.02 */
 	/* See sections 2.2.4 and 3.2.4.1.5 of MS-SMB2 */
-	if ((tcon->ses) && (tcon->ses->server) &&
-	    (tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
+	if (server && (server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
 		shdr->CreditCharge = cpu_to_le16(1);
 	/* else CreditCharge MBZ */
 
@@ -148,8 +146,7 @@ smb2_hdr_assemble(struct smb2_sync_hdr *shdr, __le16 smb2_cmd,
 /*	if (tcon->share_flags & SHI1005_FLAGS_DFS)
 		shdr->Flags |= SMB2_FLAGS_DFS_OPERATIONS; */
 
-	if (tcon->ses && tcon->ses->server && tcon->ses->server->sign &&
-	    !smb3_encryption_required(tcon))
+	if (server && server->sign && !smb3_encryption_required(tcon))
 		shdr->Flags |= SMB2_FLAGS_SIGNED;
 out:
 	return;
@@ -267,12 +264,12 @@ static inline int __smb2_reconnect(const struct nls_table *nlsc,
 #endif
 
 static int
-smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
+smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
+	       struct TCP_Server_Info *server)
 {
 	int rc;
 	struct nls_table *nls_codepage;
 	struct cifs_ses *ses;
-	struct TCP_Server_Info *server;
 	int retries;
 
 	/*
@@ -301,12 +298,10 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
 		}
 	}
 	if ((!tcon->ses) || (tcon->ses->status == CifsExiting) ||
-	    (!tcon->ses->server))
+	    (!tcon->ses->server) || !server)
 		return -EIO;
 
 	ses = tcon->ses;
-	server = ses->server;
-
 	retries = server->nr_targets;
 
 	/*
@@ -439,7 +434,9 @@ failed:
 }
 
 static void
-fill_small_buf(__le16 smb2_command, struct cifs_tcon *tcon, void *buf,
+fill_small_buf(__le16 smb2_command, struct cifs_tcon *tcon,
+	       struct TCP_Server_Info *server,
+	       void *buf,
 	       unsigned int *total_len)
 {
 	struct smb2_sync_pdu *spdu = (struct smb2_sync_pdu *)buf;
@@ -452,7 +449,7 @@ fill_small_buf(__le16 smb2_command, struct cifs_tcon *tcon, void *buf,
 	 */
 	memset(buf, 0, 256);
 
-	smb2_hdr_assemble(&spdu->sync_hdr, smb2_command, tcon);
+	smb2_hdr_assemble(&spdu->sync_hdr, smb2_command, tcon, server);
 	spdu->StructureSize2 = cpu_to_le16(parmsize);
 
 	*total_len = parmsize + sizeof(struct smb2_sync_hdr);
@@ -464,7 +461,8 @@ fill_small_buf(__le16 smb2_command, struct cifs_tcon *tcon, void *buf,
  * function must have filled in request_buf pointer.
  */
 static int __smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
-				  void **request_buf, unsigned int *total_len)
+				 struct TCP_Server_Info *server,
+				 void **request_buf, unsigned int *total_len)
 {
 	/* BB eventually switch this to SMB2 specific small buf size */
 	if (smb2_command == SMB2_SET_INFO)
@@ -476,7 +474,7 @@ static int __smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
 		return -ENOMEM;
 	}
 
-	fill_small_buf(smb2_command, tcon,
+	fill_small_buf(smb2_command, tcon, server,
 		       (struct smb2_sync_hdr *)(*request_buf),
 		       total_len);
 
@@ -490,27 +488,30 @@ static int __smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
 }
 
 static int smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
+			       struct TCP_Server_Info *server,
 			       void **request_buf, unsigned int *total_len)
 {
 	int rc;
 
-	rc = smb2_reconnect(smb2_command, tcon);
+	rc = smb2_reconnect(smb2_command, tcon, server);
 	if (rc)
 		return rc;
 
-	return __smb2_plain_req_init(smb2_command, tcon, request_buf,
+	return __smb2_plain_req_init(smb2_command, tcon, server, request_buf,
 				     total_len);
 }
 
 static int smb2_ioctl_req_init(u32 opcode, struct cifs_tcon *tcon,
+			       struct TCP_Server_Info *server,
 			       void **request_buf, unsigned int *total_len)
 {
 	/* Skip reconnect only for FSCTL_VALIDATE_NEGOTIATE_INFO IOCTLs */
 	if (opcode == FSCTL_VALIDATE_NEGOTIATE_INFO) {
-		return __smb2_plain_req_init(SMB2_IOCTL, tcon, request_buf,
-					     total_len);
+		return __smb2_plain_req_init(SMB2_IOCTL, tcon, server,
+					     request_buf, total_len);
 	}
-	return smb2_plain_req_init(SMB2_IOCTL, tcon, request_buf, total_len);
+	return smb2_plain_req_init(SMB2_IOCTL, tcon, server,
+				   request_buf, total_len);
 }
 
 /* For explanation of negotiate contexts see MS-SMB2 section 2.2.3.1 */
@@ -858,7 +859,8 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		return -EIO;
 	}
 
-	rc = smb2_plain_req_init(SMB2_NEGOTIATE, NULL, (void **) &req, &total_len);
+	rc = smb2_plain_req_init(SMB2_NEGOTIATE, NULL, server,
+				 (void **) &req, &total_len);
 	if (rc)
 		return rc;
 
@@ -916,7 +918,8 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	rqst.rq_iov = iov;
 	rqst.rq_nvec = 1;
 
-	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
+	rc = cifs_send_recv(xid, ses, server,
+			    &rqst, &resp_buftype, flags, &rsp_iov);
 	cifs_small_buf_release(req);
 	rsp = (struct smb2_negotiate_rsp *)rsp_iov.iov_base;
 	/*
@@ -1227,8 +1230,9 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	unsigned int total_len;
 
-	rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, (void **) &req,
-			     &total_len);
+	rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, server,
+				 (void **) &req,
+				 &total_len);
 	if (rc)
 		return rc;
 
@@ -1305,6 +1309,7 @@ SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
 
 	/* BB add code to build os and lm fields */
 	rc = cifs_send_recv(sess_data->xid, sess_data->ses,
+			    cifs_ses_server(sess_data->ses),
 			    &rqst,
 			    &sess_data->buf0_type,
 			    CIFS_LOG_ERROR | CIFS_NEG_OP, &rsp_iov);
@@ -1689,7 +1694,8 @@ SMB2_logoff(const unsigned int xid, struct cifs_ses *ses)
 	if (ses->need_reconnect)
 		goto smb2_session_already_dead;
 
-	rc = smb2_plain_req_init(SMB2_LOGOFF, NULL, (void **) &req, &total_len);
+	rc = smb2_plain_req_init(SMB2_LOGOFF, NULL, ses->server,
+				 (void **) &req, &total_len);
 	if (rc)
 		return rc;
 
@@ -1710,7 +1716,8 @@ SMB2_logoff(const unsigned int xid, struct cifs_ses *ses)
 	rqst.rq_iov = iov;
 	rqst.rq_nvec = 1;
 
-	rc = cifs_send_recv(xid, ses, &rqst, &resp_buf_type, flags, &rsp_iov);
+	rc = cifs_send_recv(xid, ses, ses->server,
+			    &rqst, &resp_buf_type, flags, &rsp_iov);
 	cifs_small_buf_release(req);
 	/*
 	 * No tcon so can't do
@@ -1751,7 +1758,10 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	__le16 *unc_path = NULL;
 	int flags = 0;
 	unsigned int total_len;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server;
+
+	/* always use master channel */
+	server = ses->server;
 
 	cifs_dbg(FYI, "TCON\n");
 
@@ -1772,8 +1782,8 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	/* SMB2 TREE_CONNECT request must be called with TreeId == 0 */
 	tcon->tid = 0;
 	atomic_set(&tcon->num_remote_opens, 0);
-	rc = smb2_plain_req_init(SMB2_TREE_CONNECT, tcon, (void **) &req,
-			     &total_len);
+	rc = smb2_plain_req_init(SMB2_TREE_CONNECT, tcon, server,
+				 (void **) &req, &total_len);
 	if (rc) {
 		kfree(unc_path);
 		return rc;
@@ -1812,7 +1822,8 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	/* Need 64 for max size write so ask for more in case not there yet */
 	req->sync_hdr.CreditRequest = cpu_to_le16(64);
 
-	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
+	rc = cifs_send_recv(xid, ses, server,
+			    &rqst, &resp_buftype, flags, &rsp_iov);
 	cifs_small_buf_release(req);
 	rsp = (struct smb2_tree_connect_rsp *)rsp_iov.iov_base;
 	trace_smb3_tcon(xid, tcon->tid, ses->Suid, tree, rc);
@@ -1897,8 +1908,9 @@ SMB2_tdis(const unsigned int xid, struct cifs_tcon *tcon)
 
 	close_shroot_lease(&tcon->crfid);
 
-	rc = smb2_plain_req_init(SMB2_TREE_DISCONNECT, tcon, (void **) &req,
-			     &total_len);
+	rc = smb2_plain_req_init(SMB2_TREE_DISCONNECT, tcon, ses->server,
+				 (void **) &req,
+				 &total_len);
 	if (rc)
 		return rc;