cifs: add function to get a tcon from cifs_sb

When we convert cifs to do multiple sessions per mount, we'll need more
than one tcon per superblock. At that point "cifs_sb->tcon" will make
no sense. Add a new accessor function that gets a tcon given a cifs_sb.
For now, it just returns cifs_sb->tcon. Later it'll do more.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index d7784a9..3efc242 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -102,7 +102,7 @@
 		return NULL;
 	}
 
-	if (CIFS_SB(sb)->tcon->nocase)
+	if (cifs_sb_tcon(CIFS_SB(sb))->nocase)
 		dentry->d_op = &cifs_ci_dentry_ops;
 	else
 		dentry->d_op = &cifs_dentry_ops;
@@ -171,7 +171,7 @@
 cifs_std_info_to_fattr(struct cifs_fattr *fattr, FIND_FILE_STANDARD_INFO *info,
 		       struct cifs_sb_info *cifs_sb)
 {
-	int offset = cifs_sb->tcon->ses->server->timeAdj;
+	int offset = cifs_sb_tcon(cifs_sb)->ses->server->timeAdj;
 
 	memset(fattr, 0, sizeof(*fattr));
 	fattr->cf_atime = cnvrtDosUnixTm(info->LastAccessDate,
@@ -199,7 +199,7 @@
 	int len;
 	int oplock = 0;
 	int rc;
-	struct cifsTconInfo *ptcon = cifs_sb->tcon;
+	struct cifsTconInfo *ptcon = cifs_sb_tcon(cifs_sb);
 	char *tmpbuffer;
 
 	rc = CIFSSMBOpen(xid, ptcon, full_path, FILE_OPEN, GENERIC_READ,
@@ -241,7 +241,7 @@
 	cifsFile = file->private_data;
 	cifsFile->invalidHandle = true;
 	cifsFile->srch_inf.endOfSearch = false;
-	cifsFile->tcon = cifs_sb->tcon;
+	cifsFile->tcon = cifs_sb_tcon(cifs_sb);
 	pTcon = cifsFile->tcon;
 	if (pTcon == NULL)
 		return -EINVAL;