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    SubjectRe: [PATCH 0/6] kernel tinification: optionally compile out splice family of syscalls (splice, vmsplice, tee and sendfile)
    On Sun, 23 Nov 2014 15:36:37 -0800
    Josh Triplett <josh@joshtriplett.org> wrote:

    > On Sun, Nov 23, 2014 at 09:30:40PM +0100, Pieter Smith wrote:
    > > On Sun, Nov 23, 2014 at 11:43:26AM -0800, Josh Triplett wrote:
    > > > On Sun, Nov 23, 2014 at 01:46:23PM -0500, David Miller wrote:
    > > > > Truly removing sendfile/sendpage means that you can't even compile NFS
    > > > > into the tree.
    > > >
    > > > If you mean the in-kernel nfsd (CONFIG_NFSD), that already has a large
    > > > stack of "select" and "depends on", both directly and indirectly; adding
    > > > a "select SPLICE_SYSCALL" to it seems fine. (That select does need
    > > > adding, though. Pieter, you need to test-compile more than just
    > > > tinyconfig and defconfig. Try an allyesconfig with *just* splice turned
    > > > off, and make sure that compiles.)
    > >
    > > Did exacly that. Took forever on my hardware, but no problems.
    >
    > Ah, I see. Looking more closely at nfsd, it looks like it already has a
    > code path for filesystems that don't do splice. I think, rather than
    > making nfsd select SPLICE_SYSCALL, that it would suffice to change the
    > "rqstp->rq_splice_ok = true;" in svc_process_common (net/sunrpc/svc.c)
    > to:
    >
    > rqstp->rq_splice_ok = IS_ENABLED(CONFIG_SPLICE_SYSCALL);
    >
    > Then nfsd should simply *always* fall back to its non-splice support.
    >

    I'd probably prefer the above, actually. We have to keep supporting
    non-splice enabled fs' for the forseeable future, so we may as well
    allow people to run nfsd in such configurations. It could even be
    useful for testing the non-splice-enabled codepaths.

    > That said, given that it seems exceedingly unlikely that anyone would
    > use the in-kernel nfsd on a system trying to minimize kernel size, it
    > still seems cleaner to just "select SPLICE_SYSCALL" from NFSD in
    > Kconfig. That avoids making any changes at all to the nfsd source in
    > this patch series.
    >

    --
    Jeff Layton <jlayton@poochiereds.net>


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