jbd2: move superblock checksum calculation to jbd2_write_superblock()

Some of the functions which modify the jbd2 superblock were not
updating the checksum before calling jbd2_write_superblock().  Move
the call to jbd2_superblock_csum_set() to jbd2_write_superblock(), so
that the checksum is calculated consistently.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: stable@vger.kernel.org

fs/jbd2/journal.c

@@ -1335,6 +1335,7 @@ static int journal_reset(journal_t *journal)
 static void jbd2_write_superblock(journal_t *journal, int write_op)
 {
 	struct buffer_head *bh = journal->j_sb_buffer;
+	journal_superblock_t *sb = journal->j_superblock;
 	int ret;
 
 	trace_jbd2_write_superblock(journal, write_op);
@@ -1356,6 +1357,7 @@ static void jbd2_write_superblock(journal_t *journal, int write_op)
 		clear_buffer_write_io_error(bh);
 		set_buffer_uptodate(bh);
 	}
+	jbd2_superblock_csum_set(journal, sb);
 	get_bh(bh);
 	bh->b_end_io = end_buffer_write_sync;
 	ret = submit_bh(write_op, bh);
@@ -1452,7 +1454,6 @@ void jbd2_journal_update_sb_errno(journal_t *journal)
 	jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
 		  journal->j_errno);
 	sb->s_errno    = cpu_to_be32(journal->j_errno);
-	jbd2_superblock_csum_set(journal, sb);
 	read_unlock(&journal->j_state_lock);
 
 	jbd2_write_superblock(journal, WRITE_SYNC);