Re: mmap over nfs leads to excessive system load

[Chuck Lever]

Trond Myklebust wrote:
> On Wed, 2005-11-16 at 14:39 -0800, Kenny Simpson wrote:
>
> > --- Trond Myklebust <trond.myklebust@xxxxxxxxxx> wrote:
> >
> > > I'm getting lost here. Please could you spell out the testcases that are
> > > not working.
> >
> > I've redone my test cases and have confirmed that O_DIRECT with pwrite64 triggers the bad
> > condition.
> >
> > The cases that are fine are:
> >  pwrite64
> >  ftruncate with O_DIRECT
> >  ftruncate
> >
> > Also, when the system is in this state, if I try to 'ls' the file,
> > the 'ls' process becomes stuck in state D in sync_page.  stracing the 'ls'
> > shows it is in a call to stat64.
> >
> > -Kenny
>
>
> Chuck, can you take a look at this?
>
> Kenny is seeing a hang when using pwrite64() on an O_DIRECT file
> and the file size exceeds 4Gb. Server is a NetApp filer w/ NFSv3.
>
> I had a quick look at nfs_file_direct_write(), and among other things,
> it would appear that it is not doing any of the usual overflow checks on
> *pos and the count size (see generic_write_checks()). In particular,
> checks are missing against overflow vs. MAX_NON_LFS if O_LARGEFILE is
> not set (and also against overflow vs. s_maxbytes, but that is less
> relevant here).

'uname -a' on the client?

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