there is no point to update in-bh inode every call to osd_ldiskfs_write_record(), but
the following construction makes it so:

        dirty_inode = test_and_set_bit(LDISKFS_INODE_JOURNAL_DATA,
                                       &ei->i_flags);
....
        if (dirty_inode)
                osd_dirty_inode(inode, I_DIRTY_DATASYNC);

there are two consequences:
1) transaction can exceed declared credits as osd_declare_write() doesn't reserve inode for overwrite case (then current operation aborts with -ENOSPC and filesystem turns read-only)
2) overwrites copy inode into buffer cache impacting performance, should be especially visible with changelogs enabled, where every record causes at least two separate writes