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>

1 files changed, 7 insertions, 7 deletions

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 4d4cb26d2ae1..100d04af62b1 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -1020,6 +1020,7 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
 
 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)
 {
@@ -1031,20 +1032,17 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	};
 	unsigned int instance;
 	char *buf;
-	struct TCP_Server_Info *server;
 
 	optype = flags & CIFS_OP_MASK;
 
 	for (i = 0; i < num_rqst; i++)
 		resp_buf_type[i] = CIFS_NO_BUFFER;  /* no response buf yet */
 
-	if ((ses == NULL) || (ses->server == NULL)) {
+	if (!ses || !ses->server || !server) {
 		cifs_dbg(VFS, "Null session\n");
 		return -EIO;
 	}
 
-	server = cifs_pick_channel(ses);
-
 	if (server->tcpStatus == CifsExiting)
 		return -ENOENT;
 
@@ -1239,11 +1237,12 @@ out:
 
 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)
 {
-	return compound_send_recv(xid, ses, flags, 1, rqst, resp_buf_type,
-				  resp_iov);
+	return compound_send_recv(xid, ses, server, flags, 1,
+				  rqst, resp_buf_type, resp_iov);
 }
 
 int
@@ -1278,7 +1277,8 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses,
 	rqst.rq_iov = new_iov;
 	rqst.rq_nvec = n_vec + 1;
 
-	rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov);
+	rc = cifs_send_recv(xid, ses, ses->server,
+			    &rqst, resp_buf_type, flags, resp_iov);
 	if (n_vec + 1 > CIFS_MAX_IOV_SIZE)
 		kfree(new_iov);
 	return rc;