Date: Mon, 2 Aug 2010 17:25:40 +1000
From: Nick Piggin <npiggin@suse.de>
To: Christian Stroetmann <stroetmann@ontolinux.com>
Cc: Glenn D <doiggl@velocitynet.com.au>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux reiserfs-devel <reiserfs-devel@vger.kernel.org>
Subject: Re: Formal Reiser4 inclusion and todo list?
Message-ID: <20100802072540.GA7841@amd>
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On Sun, Aug 01, 2010 at 03:43:05PM +0200, Christian Stroetmann wrote:
> Hi Glenn;
> 
> On the 28.07.2010 21:58, I wrote:
> >Aloha Glenn;
> >
> >At the 28.07.2010 17:21, you (doiggl@velocitynet.com.au) wrote:
> >>>The following items are still unaddressed:
> >>>
> >>>1. running igrab() in the writepage() path is really going to hammer
> >>>    inode_lock.  Something else will need to be done here.
> >>>
> >>>2. Running iput() in entd() is a bit surprising.  iirc there
> >>>are various
> >>>ways
> >>>    in which this can recur into the filesystem, perform I/O, etc.  I
> >>>guess it
> >>>    works..
> >>>    But again, it will hammer inode_lock.

inode_lock should be going away within 6 months or so, with the
vfs-scaling developments (see linux-fsdevel).

Inode refcounting becomes very light-weight, as it should be.


> >>>3. the writeout logic in entd_flush() is interesting (as in
> >>>"holy cow").
> >>>    It's very central and really needs some good comments describing
> >>what's
> >>>    going on in there - what problems are being solved, which decisions
> >>were
> >>>    taken and why, etc.
> >>>
> >>>4. reiser4_wait_page_writeback() needs commenting.
> >>>
> >>>5. reading the comment in txnmgr.c regarding MAP_SHARED pages: a number
> >>of
> >>>    things have changed since then.  We have page-becoming-writeable
> >>>    notifications and probably soon we'll always take a
> >>>pagefault when a
> >>>    MAP_SHARED page transitions from pte-clean to pte-dirty (although I
> >>>wouldn't
> >>>    recommend that a filesystem rely upon the latter for a while yet).

It is now possible to trap all dirtying activity from all sources
except get_user_pages (but filesystems tend to ignore that little
problem).

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