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, 19 insertions, 13 deletions

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;