Re: [patch 11/13] don't hold i_sem during O_DIRECT writes to blockdevs

[Christoph Hellwig]

On Sun, Jul 28, 2002 at 10:55:56AM -0700, Andrew Morton wrote:
> > I think I prefer option 3, it's the cleanest way of doing it.
> 
> It could be time to separate out a __generic_file_write() which
> doesn't take i_sem at all.  The ext3 tree was doing that for a
> while, to permit multipage transactions in journalled data mode.

In fact we we already have that already in the XFS tree (Steve called it
do_generic_file_write although I'd really prefer __generic_file_write).

> > A little unrelated, but as you touch the code:  what about removing the two
> > existing special cases for S_ISBLK() in generic_file_write()?  they're
> > present only to provide the old (pre-LFS) blockdevice semantics on 2.4,
> > we shouldn't keept them around forever..
> 
> hm.  Are you sure about that?  They look fairly useful to me?

The O_APPEND special casing is certainly very, very ugly - application
should use it on block devices at all - if they're screwed when doing it
anyway it's their problem.

And I think we can expect reasonable ulimits for root nowdays, although
I'm open for discussions on that one.