lkml.org 
[lkml]   [2000]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: ext2 compression status (was Re: 2.4 Features
Hi,

On Sun, 6 Feb 2000 11:37:27 +1100, Peter Moulder
<reiter@netspace.net.au> said:

>> and is there a robust 2.3 version?

> Nope. The change to Linux' write mechanism in early 2.3 (namely
> having writes go through writepage instead of having ext2_file_write
> create disk buffers) means that there's no longer a convenient place
> to do the compression (in the most common case, where we wish to
> compress more than a page full at a time). Probably the fix is to
> organise for multiple pages to be written at once. It just requires
> that someone spend a chunk of time getting familiar with how pages
> usually get written out, and the locking issues and so on. Stephen,
> since you're already familiar with both the mm system and ext2, can
> you comment on that plan?

Sure. It's not really hard to do that in 2.3.

The 2.3 VM doesn't force you to use generic_file_write().
grab_cache_page() and read_cache_page() can be used by other filesystems
to access the page cache, and you can use that in your own file_write
function to do any sort of transformations you want during the write()
system call. You don't want to use generic_file_write(), as that
assumes that the disk blocks we're using for IO correspond exactly to
the contents of the page cache. That doesn't prevent you from using
your own file_write function to update the page cache and then do any
other write-through you want to the buffer cache.

--Stephen

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:56    [W:0.064 / U:1.196 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site