hammer_alloc_data panic

[Matthew Dillon]

:...
:> *some* of the space in each of those 16 blocks while filling up a new
:> block, but the new block may become completely full before any one of those
:> 16 blocks becomes completely empty.  So another new block needs
:> to be allocated.
:
:Oh I see, that's in clear contrast to LFS.  Is it possible to find all
:b-tree elements (or rather, their parents) when looking at one block?
:
:cheers
:  simon

    ... by scanning the B-Tree yes.  With some sort of direct lookup?  No.

    This is the trade-off I made using a coarse-grained storage layer verses
    the A-list based fine-grained one I originally envisioned.   Though
    nothing prevents HAMMER from being able to use a fine-grained storage
    layer, if we can swing using the coarse-grained layer we reap some
    phenominal advantages, not the least of which being that the management
    overhead of the storage layer outside the reblocking function is about
    as close to 0 as it is possible to get.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>