Re: partial reiser4 review comments

[Christoph Hellwig <hch@infradead.org>]

On Thu, Aug 03, 2006 at 12:17:41AM -0700, Andrew Morton wrote:
> - running igrab() in the writepage() path is really going to hammer
>   inode_lock.  Something else will need to be done here.

> - 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.

XFS used to do this and it caused lots of problems.  What xfs does now
is to keep an iocount in the inode for outstanding I/Os and ->clear_inode
waits for that I/O to finish using hashed waitqueues.  It would be nice
to have a facility like that in generic code.

> - reiser4_readpages() shouldn't need to clean up the remaining pages on
>   *pages.  read_cache_pages() does that now.

Without looking at the code I remember someone from the Namesys people told
me they could use plain mpage_readpages now.  Anything still blocking using
that function?

> - General comment: the lack of support for extended attributes, access
>   control lists and direct-io is a big problem and it's getting bigger.  I
>   don't see how a vendor could support reiser4 without these features and
>   permanent lack of vendor support will hurt.
> 
>   What's the plan here?

Another issue is the lack of support for blocksize < pagesize.   This prevents
it from beeing used across architectures.  Even worse when I tried the last
time it didn't allow me to create a 64k blocksize filesystem that I could
actually test on ppc64.