ceph: use ceph_sb_to_client instead of ceph_client

ceph_sb_to_client and ceph_client are really identical, we need to dump
one; while function ceph_client is confusing with "struct ceph_client",
ceph_sb_to_client's definition is more clear; so we'd better switch all
call to ceph_sb_to_client.

  -static inline struct ceph_client *ceph_client(struct super_block *sb)
  -{
  -	return sb->s_fs_info;
  -}

Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 110857b..93ad169 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -107,8 +107,8 @@
 static int ceph_syncfs(struct super_block *sb, int wait)
 {
 	dout("sync_fs %d\n", wait);
-	ceph_osdc_sync(&ceph_client(sb)->osdc);
-	ceph_mdsc_sync(&ceph_client(sb)->mdsc);
+	ceph_osdc_sync(&ceph_sb_to_client(sb)->osdc);
+	ceph_mdsc_sync(&ceph_sb_to_client(sb)->mdsc);
 	dout("sync_fs %d done\n", wait);
 	return 0;
 }
@@ -932,9 +932,9 @@
 		goto out;
 	}
 
-	if (ceph_client(sb) != client) {
+	if (ceph_sb_to_client(sb) != client) {
 		ceph_destroy_client(client);
-		client = ceph_client(sb);
+		client = ceph_sb_to_client(sb);
 		dout("get_sb got existing client %p\n", client);
 	} else {
 		dout("get_sb using new client %p\n", client);