Add missing locking to reiserfs_quota_read() and reiserfs_quota_write().

Signed-off-by: Jan Kara <jack@suse.cz>

--- linux/fs/reiserfs/super.c	2005-01-27 12:56:27.000000000 +0100
+++ linux/fs/reiserfs/super.c	2005-01-27 17:41:20.000000000 +0100
@@ -1993,7 +1993,9 @@ static ssize_t reiserfs_quota_read(struc
 	tocopy = sb->s_blocksize - offset < toread ? sb->s_blocksize - offset : toread;
 	tmp_bh.b_state = 0;
 	/* Quota files are without tails so we can safely use this function */
+	reiserfs_write_lock(sb);
 	err = reiserfs_get_block(inode, blk, &tmp_bh, 0);
+	reiserfs_write_unlock(sb);
 	if (err)
 	    return err;
 	if (!buffer_mapped(&tmp_bh))    /* A hole? */
@@ -2041,8 +2043,11 @@ static ssize_t reiserfs_quota_write(stru
 	    err = -EIO;
 	    goto out;
 	}
+	lock_buffer(bh);
 	memcpy(bh->b_data+offset, data, tocopy);
+	flush_dcache_page(bh->b_page);
 	set_buffer_uptodate(bh);
+	unlock_buffer(bh);
 	reiserfs_prepare_for_journal(sb, bh, 1);
 	journal_mark_dirty(current->journal_info, sb, bh);
 	if (!journal_quota)