clonexfs could not handle big fs(over several T) correctly.

[Finix1979]

Hi, Maintainer

I create a sparse disk (30T) and create an XFS on it by default setting(blocksize=4k). With this empty fs, xfsclone could not figure out the correct dirty bitmap.

The root cause is function addtohist should convert mp->m_sb.sb_agblocks from uint32 to uint64. like this:

start_block = (agno* (unsigned long long)mp->m_sb.sb_agblocks) + agbno;

BTW, after calling libxfs_readbuf, libxfs_putbuf is needed.

Thanks