Set sbi->s_journal to NULL after we call journal_destroy(). This
will be later needed because after journal_destroy() is called,
ext4_clear_inode() can still be called for some inodes (e.g. root
inode) and we'll need to detect there that journal doesn't exists
anymore.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
        ext4_ext_release(sb);
        ext4_xattr_put_super(sb);
        jbd2_journal_destroy(sbi->s_journal);
+       sbi->s_journal = NULL;
        if (!(sb->s_flags & MS_RDONLY)) {
                EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
                es->s_state = cpu_to_le16(sbi->s_mount_state);
 
 failed_mount4:
        jbd2_journal_destroy(sbi->s_journal);
+       sbi->s_journal = NULL;
 failed_mount3:
        percpu_counter_destroy(&sbi->s_freeblocks_counter);
        percpu_counter_destroy(&sbi->s_freeinodes_counter);