[Unionfs] RT patch - again

[Erez Zadok]

In message <200711221317.39711.paul at gccs.co.za>, Paul Hewlett writes:
> Please ignore previous post - here is correct patch (apologies)
> 
> diff -urN unionfs.org/dentry.c unionfs/dentry.c
> --- unionfs.org/dentry.c	2007-11-22 13:08:11.000000000 +0200
> +++ unionfs/dentry.c	2007-11-20 09:32:24.000000000 +0200
> @@ -268,7 +268,7 @@
>  	/* remove all non-private mappings */
>  	unmap_mapping_range(inode->i_mapping, 0, 0, 0);
>  
> -	if (inode->i_data.nrpages)
> +	if (mapping_nrpages(&inode->i_data))
>  		truncate_inode_pages(&inode->i_data, 0);
>  }
>  
> diff -urN unionfs.org/super.c unionfs/super.c
> --- unionfs.org/super.c	2007-11-22 13:07:46.000000000 +0200
> +++ unionfs/super.c	2007-11-20 09:32:10.000000000 +0200
> @@ -71,7 +71,7 @@
>  {
>  	i_size_write(inode, 0);	/* every f/s seems to do that */
>  
> -	if (inode->i_data.nrpages)
> +	if (mapping_nrpages(&inode->i_data))
>  		truncate_inode_pages(&inode->i_data, 0);
>  
>  	clear_inode(inode);

Paul, the problem with this patch, as I alluded to in my previous email, is
that unionfs won't compile unless the RT patches are applied: the vanilla
kernel doesn't have a mapping_nrpages() function.  I'd like to avoid keeping
two sets of unionfs-patches, one for RT users and one for those who don't
use RT.  I could have created a simple wrapper macro to replace
mapping_nrpages when the RT patches are not applied, but I can't b/c the RT
patches also changed the nrpages field to __nrpages; there's no way to
discover that difference at cpp/compile time (I'll need to use an Autoconf
macro ala AC_CHECK_STRUCT_FIELD :-)

What I can do in the mean time is keep such unionfs RT patches available on
the Web site.

Cheers,
Erez.