Re: [RFC] first try for swap prefetch

[Andrew Morton <akpm@digeo.com>]

Thomas Schlichter <schlicht@uni-mannheim.de> wrote:
>
> How can I get the file pointer for a buffered page with the information 
> available in the kswapd (minly the page struct)??

You can't, really.  There can be any number of file*'s pointing at an inode.

The pagefault handler will find it by find_vma(faulting_address)->vm_file. 
Other codepaths use syscalls, and the user passed the file* in.

You can call page_cache_readahead() with a NULL file*.  That'll mostly work
except for the odd filesytem like NFS which will oops.  But it's good enough
for testing and development.

Or you could cook up a local file struct along the lines of
fs/nfsd/vfs.c:nfsd_read(), but I would not like to lead a young person
that way ;)