cifs: Refactor out cifs_mount()

* Split and refactor the very large function cifs_mount() in multiple
  functions:

- tcp, ses and tcon setup to mount_get_conns()
- tcp, ses and tcon cleanup in mount_put_conns()
- tcon tlink setup to mount_setup_tlink()
- remote path checking to is_path_remote()

* Implement 2 version of cifs_mount() for DFS-enabled builds and
  non-DFS-enabled builds (CONFIG_CIFS_DFS_UPCALL).

In preparation for DFS failover support.
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsproto.h

@@ -213,7 +213,7 @@ extern int cifs_match_super(struct super_block *, void *);
 extern void cifs_cleanup_volume_info(struct smb_vol *pvolume_info);
 extern struct smb_vol *cifs_get_volume_info(char *mount_data,
 					    const char *devname, bool is_smb3);
-extern int cifs_mount(struct cifs_sb_info *, struct smb_vol *);
+extern int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol);
 extern void cifs_umount(struct cifs_sb_info *);
 extern void cifs_mark_open_files_invalid(struct cifs_tcon *tcon);
 extern void cifs_reopen_persistent_handles(struct cifs_tcon *tcon);
@@ -524,6 +524,8 @@ extern int E_md4hash(const unsigned char *passwd, unsigned char *p16,
 			const struct nls_table *codepage);
 extern int SMBencrypt(unsigned char *passwd, const unsigned char *c8,
 			unsigned char *p24);
+extern void
+cifs_cleanup_volume_info_contents(struct smb_vol *volume_info);
 
 void cifs_readdata_release(struct kref *refcount);
 int cifs_async_readv(struct cifs_readdata *rdata);