> > updating mtime in VOP_GETPAGES means that you can see new mtime + old data.
> > as pointed out, it has bad effects to eg. nfs cache coherency.
> 
> new mtime and old data is not a problem for NFS,
> it's old mtime and new data that would be trouble.
> but I see your point.

it's a problem because once an nfs client get new mtime + old data,
it has no way to notice new data.
otoh, old mtime + new data should not be a big problem because
the client will notice the new mtime on the next cache validation.

YAMAMOTO Takashi