Re: [patch] Fix broken inode clustering

[Lachlan McIlroy <lachlan@sgi.com>]

Looks good Dave.

David Chinner wrote:
> The radix tree based inode caches did away with the inode cluster hashes,
> replacing them with a bunch of masking and gang lookups on the radix tree.
> 
> This masking got broken when moving the code to per-ag radix trees and
> indexing by agino # rather than straight inode number. The result is
> clustered inode writeback does not cluster and things can go extremely
> slowly when there are lots of inodes to write.
> 
> The following patch fixes this up by comparing agino # of the inode
> found to the index of the cluster we are looking for.
> 
> Signed-off-by: Dave Chinner <dgc@sgi.com>
> Tested-by: Torsten Kaiser <just.for.lkml@googlemail.com>
> 
> ---
>  fs/xfs/xfs_iget.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: 2.6.x-xfs-new/fs/xfs/xfs_iget.c
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_iget.c	2007-11-02 13:44:46.000000000 +1100
> +++ 2.6.x-xfs-new/fs/xfs/xfs_iget.c	2007-11-07 13:08:42.534440675 +1100
> @@ -248,7 +248,7 @@ finish_inode:
>  	icl = NULL;
>  	if (radix_tree_gang_lookup(&pag->pag_ici_root, (void**)&iq,
>  							first_index, 1)) {
> -		if ((iq->i_ino & mask) == first_index)
> +		if ((XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) == first_index)
>  			icl = iq->i_cluster;
>  	}
>  
> 
> 
>