CIFS: Use multicredits for SMB 2.1/3 writes

If we negotiate SMB 2.1 and higher version of the protocol and
a server supports large write buffer size, we need to consume 1
credit per 65536 bytes. So, we need to know how many credits
we have and obtain the required number of them before constructing
a writedata structure in writepages and iovec write.

Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index de49d7a37b00..c31ce98c1704 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -90,6 +90,9 @@ extern struct mid_q_entry *cifs_setup_async_request(struct TCP_Server_Info *,
                                                 struct smb_rqst *);
 extern int cifs_check_receive(struct mid_q_entry *mid,
                         struct TCP_Server_Info *server, bool log_error);
+extern int cifs_wait_mtu_credits(struct TCP_Server_Info *server,
+                                 unsigned int size, unsigned int *num,
+                                 unsigned int *credits);
 extern int SendReceive2(const unsigned int /* xid */ , struct cifs_ses *,
                         struct kvec *, int /* nvec to send */,
                         int * /* type of buf returned */ , const int flags);