clustering issues (replacing code that used to be in
ufs/ufs/ufs_readwrite.c). vm_fault also now uses the new VM page counter
inlines.
This completes the changeover from vnode->v_lastr to vm_entry_t->v_lastr
for VM, and fp->f_nextread and fp->f_seqcount (which have been in the
tree for a while). Determination of the I/O strategy (sequential, random,
and so forth) is now handled on a descriptor-by-descriptor basis for
base I/O calls, and on a memory-region-by-memory-region and
process-by-process basis for VM faults.
Reviewed by: David Greenman <dg@root.com>, Alan Cox <alc@cs.rice.edu>
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