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Re: [PATCH] Re: zero-filed page on VOP_PUTPAGES

YAMAMOTO Takashi <> wrote:

> > +                       rvap->va_size = MAX(rvap->va_size, vp->v_size);
> > + 
> couldn't it be a problem if the size of the file is shrinked by the server?

I am back to this simple fix, after the failure of attempts to avoid
uvm_vnp_setsize() calls from puffs_vnop_getattr() while a
PUFFS_VN_SETATTR is in progress. 

Keeping track of the end of a PUFFS_VN_SETATTR operation turns to be
troublesome. The operation needs to be asynchronous when done by a
kernel thread responsible for freeing memory, otherwise we get a
deadlock. Using puffs_msg_setcall() to get notified of completion does
not help, as soon as I use it, the machine hangs on low memory

Keeping MAX(rvap->va_size, vp->v_size) in puffs_vnop_getattr() is simple
but it has a drawback with distributed filesystems: a client will not
notify that an open file was shrunk by another client. I think this is
better than deadlocks and data corruption. 

If nobody has a better idea, I will got with this simple fix.

Emmanuel Dreyfus

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