Questions about pagebuf code

[Craig Tierney <ctierney@xxxxxxxx>]

1) Are the versions of xfs in 2.4.26 and 2.6.x mostly the same
   (except for the change in kernel interface)?  In particular
   are there any differences in the pagebuf code?
2) Are all memory allocations controlled through xfs_buf?
   Not just the actual {v,k}mallocs (I grepped that to verify)
   but any time a routine chooses to access a page, it is selected
   through routines in xfs_buf?
3) Does pagebuf_get_pages get called multiple times while
   the filesystem is active, or only at initialization?
4) Would there be any reason (except performance) not to change
   MAX_SLAB_SIZE to a smaller values (like 0), to test the behavior
   when only kmalloc is used to allocation memory?

Thanks,
Craig