Re: [RFC 15/16] ext2: Add variable page size support

[Badari Pulavarty <pbadari@gmail.com>]

On Sun, 2007-04-22 at 23:50 -0700, Christoph Lameter wrote:
> ext2: Add variable page size support
> 
> This adds variable page size support. It is then possible to mount filesystems
> that have a larger blocksize than the page size.
> 
> F.e. the following is possible on x86_64 and i386 that have only a 4k page
> size.
> 
> mke2fs -b 16384 /dev/hdd2	<Ignore warning about too large block size>
> 
> mount /dev/hdd2 /media
> ls -l /media
> 
> .... Do more things with the volume that uses a 16k page cache size on
> a 4k page sized platform..
> 
> Note that there are issues with ext2 support:
> 
> 1. Data is not writtten back correctly (block layer?)
> 2. Reclaim does not work right.

Here is the fix you need to get ext2 writeback working properly :)
I am able to run fsx with this fix (without mapped IO).

Thanks,
Badari

 fs/buffer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.21-rc7/fs/buffer.c
===================================================================
--- linux-2.6.21-rc7.orig/fs/buffer.c	2007-04-23 09:44:19.000000000 -0700
+++ linux-2.6.21-rc7/fs/buffer.c	2007-04-23 10:28:45.000000000 -0700
@@ -1619,7 +1619,7 @@ static int __block_write_full_page(struc
 	 * handle that here by just cleaning them.
 	 */
 
-	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	block = (sector_t)page->index << (page_cache_shift(page->mapping) - inode->i_blkbits);
 	head = page_buffers(page);
 	bh = head;
 


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