On 07/23/2010 01:46 PM, Minchan Kim wrote:

On Fri, Jul 23, 2010 at 4:36 PM, Nitin Gupta [off-list ref] wrote:

quoted

2. I think change in btrfs can be avoided by moving cleancache_get_page()
from do_mpage_reapage() to filemap_fault() and this should work for all
filesystems. See:

handle_pte_fault() -> do_(non)linear_fault() -> __do_fault()
                                               -> vma->vm_ops->fault()

which is defined as filemap_fault() for all filesystems. If some future
filesystem uses its own custom function (why?) then it will have to arrange for
call to cleancache_get_page(), if it wants this feature.

filemap fault works only in case of file-backed page which is mapped
but don't work not-mapped cache page.  So we could miss cache page by
read system call if we move it into filemap_fault.

Oh, yes. Then we need cleancache_get_page() call in do_generic_file_read() too.
So, if I am missing anything now, we should now be able to get rid of per-fs
changes.

Thanks,
Nitin