Re: + fs-introduce-write_begin-write_end-and-perform_write-aops.patch added to -mm tree

[Nick Piggin <npiggin@suse.de>]

On Tue, May 29, 2007 at 02:19:55PM -0700, Andrew Morton wrote:
> 
> The patch titled
>      fs: introduce write_begin, write_end, and perform_write aops
> has been added to the -mm tree.  Its filename is
>      fs-introduce-write_begin-write_end-and-perform_write-aops.patch
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
> out what to do about this
> 
> ------------------------------------------------------
> Subject: fs: introduce write_begin, write_end, and perform_write aops
> From: Nick Piggin <npiggin@suse.de>
> 
> These are intended to replace prepare_write and commit_write with more
> flexible alternatives that are also able to avoid the buffered write
> deadlock problems efficiently (which prepare_write is unable to do).

OK, well now Andrew's merged a significant chunk of this work, I
would like to try getting the clustered filesystem patches back
in too (Steven, the last GFS2 patch you sent had rejects against this
tree, so I dropped it... hope it isn't too much work to bring it back
uptodate?).

The cluster filesystems aren't 100% happy with the backward-compat
code, because pagecache_write_end cannot handle AOP_TRUNCATED_PAGE from
->commit_write... so if you were to try using loop over GFS2, it might
go BUG. This is a bit bad of me, however the compat code would have been
a whole lot uglier to support that, and I figure the cluster filesystems
want to convert to the new aops ASAP anyway.

I doubt anybody but the filesystem developers would be using -mm in such
a way, but even so I hope we can fix this before long.

Meanwhile, I'll look at redoing the rest of the filesystems that got
left behind.