[Ocfs2-tools-devel] libocfs2 allocation of clusters and fsck

[Zach Brown]

Joel Becker wrote:
> On Thu, Oct 28, 2004 at 10:58:28AM -0700, Zach Brown wrote:
> 
>>Mmm, that last bit is compelling.  Rather than comparing, though, it
>>seems we should just have fsck build up the bitmap as it scans and then
>>use the library to sync it back.
> 
> 	Is that what ext2 does?

Yeah, sort of.  In the passes it builds up the same data structure that
it reads the bitmaps into off of disk.  check_block_bitmaps() compares
them and fixes things by freeing the one it read of disk and putting the
one it built up in its place.

>         if (fixit == 1) {
>                 ext2fs_free_block_bitmap(fs->block_map);
>                 retval = ext2fs_copy_bitmap(ctx->block_found_map,
>                                                   &fs->block_map);

It eventually writes out that fs->block_map via the exit path in unix.c.

> 	To be fair, chains _are_ built for speedy lookup of bits, but
> not for speedy lookup of a particular group.

*nod*

- z