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    SubjectRe: [rfc][patch 0/3] a faster buffered write deadlock fix?
    On Fri, 9 Feb 2007 10:54:05 +0100 Nick Piggin <npiggin@suse.de> wrote:

    > On Fri, Feb 09, 2007 at 12:41:01AM -0800, Andrew Morton wrote:
    > > On Thu, 8 Feb 2007 14:07:15 +0100 (CET) Nick Piggin <npiggin@suse.de> wrote:
    > >
    > > > So I have finally finished a first slightly-working draft of my new aops
    > > > op (perform_write) proposal. I would be interested to hear comments about
    > > > it. Most of my issues and concerns are in the patch headers themselves,
    > > > so reply to them.
    > > >
    > > > The patches are against my latest buffered-write-fix patchset.
    > >
    > > What happened with Linus's proposal to instantiate the page as pinned,
    > > non-uptodate, unlocked and in pagecache while we poke the user address?
    >
    > That's still got a deadlock,

    It does?

    > and also it doesn't work if we want to lock
    > the page when performing a minor fault (which I want to fix fault vs
    > invalidate),

    It's hard to discuss this without a description of what you want to fix
    there, and a description of how you plan to fix it.

    > and also assumes nobody's ->nopage locks the page or
    > requires any resources that are held by prepare_write (something not
    > immediately clear to me with the cluster filesystems, at least).

    The nopage handler is filemap_nopage(). Are there any exceptions to that?

    > But that all becomes legacy path, so do we really care? Supposing fs
    > maintainers like perform_write, then after the main ones have implementations
    > we could switch over to the slow-but-correct prepare_write legacy path.
    > Or we could leave it, or we could use Linus's slightly-less-buggy scheme...
    > by that point I expect I'd be sick of arguing about it ;)

    It's worth "arguing" about. This is write(). What matters more??
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