This patch includes feedback from Andrew and Christoph. Thanks for
taking time to review.

Use of empty_zero_page was eliminated to fix compilation for architectures
that don't have it.

This patch removes setting pages up-to-date in ext2_get_xip_page and all
bug checks to verify that the page is indeed up to date.  Setting the page
state on mapping to userland is bogus.  None of the code patchs involved
with these pages in mm cares about the page state.

still on my ToDo list: identify a place outside second extended where
__inode_direct_access should reside
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/filemap_xip.c: In function `__xip_unmap':
mm/filemap_xip.c:194: request for member `pte' in something not a structure or union

Apparently pte_pfn() takes a pte_t, not a pointer to a pte_t.  From looking
at asm/page.h, it seems to be the same on ia32 or ppc (iff
STRICT_MM_TYPECHECKS is enabled, which is disabled by default on ppc).
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch reworks filemap_xip.c with the goal to reduce code duplication
from mm/filemap.c.  It applies agains 2.6.12-rc6-mm1.  Instead of
implementing the aio functions, this one implements the synchronous
read/write functions only.  For readv and writev, the generic fallback is
used.  For aio, we rely on the application doing the fallback.  Since our
"synchronous" function does memcpy immediately anyway, there is no
performance difference between using the fallbacks or implementing each
operation.
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

- generic_file* file operations do no longer have a xip/non-xip split
- filemap_xip.c implements a new set of fops that require get_xip_page
  aop to work proper. all new fops are exported GPL-only (don't like to
  see whatever code use those except GPL modules)
- __xip_unmap now uses page_check_address, which is no longer static
  in rmap.c, and defined in linux/rmap.h
- mm/filemap.h is now much more clean, plainly having just Linus'
  inline funcs moved here from filemap.c
- fix includes in filemap_xip to make it build cleanly on i386
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>