On Wed, Feb 09, 2000 at 12:02:46PM -0500, Alexander Viro wrote:
> > 256k blocks with 1k fragments (viro)
> > [also 8k blocks with 256-byte fragments!]
> ^^^
> HUH??? You want to deal with sharing sectors between the different files?
Yes. Based on my misunderstanding of how BSD did fragments, Ted and I
came up with an interestingly different way of doing fragments. Here's
the basic idea:
Keep the bitmaps of _blocks_ instead of fragments and use a second
bitmap to identify which blocks are non-full fragment blocks. Use the
last fragment in a fragment block as a fragment block descriptor to
indicate which inode each fragment belongs to (exact format still to
be determined). Fragment blocks are kept compact as otherwise we would
have to deal with internal fragmentation.
with 256k blocks, we get to grow a block group to 16GB (probably excessive
with today's discs) and then we don't have any further problems with
not enough free space.
with 2k blocks and 128 byte fragments, we get to really reduce wasted
space below any other system i've ever experienced.
