Sigh.  ramdisk almost works, except it loses data on umount.

This is because the files which are atop the ramdisk do not contribute to
dirty memory accounting, but they do need writeback.  So when sync() calls
sync_inodes_sb() to do the work, sync_inodes_sb() hopelessly underestimates
the number of pages which need writeback for a complete sync.

If you run `sync' enough times, everything eventually hits "disk" and all is
happy.

The root cause here is that the ramdisk and the files which it hosts shared
the same backing_dev_info.  This is inappropriate because the hosted files
*do* want to writeback and really should contribute to dirty memory
accounting. But the ramdisk inode itself wants neither.

So.  The patch sets up the infrastructure which permits a blockdev to provide
a separate backing_dev_info for the files which it hosts.  It's a bit of a
ramdisk-special.

Right now we ignore it, but we need to pass this down
to the low-level filesystems if we want to ever make
knfsd create symlinks with different permissions correctly.

- add module support code
- add H8/300 ELF infomation
- fix kcore ELF format

- new config items
- interface setup
- io cleanup

- config symbol fix

The code was incomplete. Let's re-do it when the other pieces
are in place.

Cset exclude: akpm@osdl.org[torvalds]|ChangeSet|20040521202003|24125

From: Andrea Arcangeli <andrea@suse.de>

this fixes the 2G limit on ramfs

From: Andrew Theurer <habanero@us.ibm.com>

Use num_online_cpus in smp_init instead of counting cpus which may or may not
really be brought up.

From: Roger Luethi <rl@hellgate.ch>

Make the comments in drivers/base/power/shutdown.c somewhat less wrong. 
There's still room for improvement :-/.

From: David Mosberger <davidm@napali.hpl.hp.com>

It used to be that loops_per_jiffy was a macro on ia64, hence it couldn't be
exported.  That's no longer the case though, so there is no point in
inhibiting its export (not that it makes any _sense_ to export that value on
ia64).

From: Rusty Russell <rusty@rustcorp.com.au>

Matthieu Castet <castet.matthieu@free.fr> pointed out that testing
cpu_online(cpu) on a UP system goes BUG().

That's because you're never supposed to ask cpu_online() about a CPU which
is >= NR_CPUS.  msr and cpuid devices use the minor to indicate the CPU
number.  Oops.

Fix is to explicitly test cpu < NR_CPUS.  Using cpu_online() is OK;
although the CPU might go down before you actually read the file, that will
simply cause junk to be returned.

A few things which Lindent got wrong.

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Pavel Machek <pavel@ucw.cz>

This patch fixes init section usage in swsusp.c: "read_suspend_image()" can
be __init.

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Stephen Leonard <stephen@phynp6.phy-astr.gsu.edu>

This fixes a counter that is unnecessarily incremented in build_zonelists().

From: Rusty Russell <rusty@rustcorp.com.au>

 From:  maximilian attems <janitor@sternwelten.at>

The "Trivial Patch Monkey" is neither documented in MAINTAINERS nor was there
a note in SubmittingPatches.

From: Rusty Russell <rusty@rustcorp.com.au>

From:  a.othieno@bluewin.ch (Arthur Othieno)

From: Rusty Russell <rusty@rustcorp.com.au>

(OK from maintainer  	David Woodhouse <dwmw2@infradead.org>)
 From:  Sam Ravnborg <sam@ravnborg.org>

  From:  <l.s.r@web.de>
  >   since the code for Linux 2.4 compatibility in fs/jffs2 is gone, we can
  >   clean up the Makefile a bit. Following patch makes the Makefile
  >   compatible with Linux 2.7 instead . :) Please consider applying.

  If we are going to clean up this I prefer we get rid of the
  local variables.
  See attached patch.

  	Sam

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Tommi Virtanen <tv@tv.debian.net>

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Pavel Machek <pavel@ucw.cz>

If we are providing "helpful" comment, it should better be correct.

From: Rusty Russell <rusty@rustcorp.com.au>

From:  David Eger <eger@theboonies.us>

Doesn't resolve.

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Marco Cova <marco.cova@studio.unibo.it>

From: Rusty Russell <rusty@rustcorp.com.au>

From:  Martin Schaffner <schaffner@gmx.li>

From: Rusty Russell <rusty@rustcorp.com.au>

From:  <adobriyan@mail.ru>

  Long block comment before declaration moves it out of page in pdfs.

  Alexey

  $ ./linux-2.6.6-rc2/scripts/kernel-doc.orig -text test.c
  struct stuff:
  struct stuff {
          int a;
          /** comment here*/char b;
  };
  Members:
  a
           aaaa
  b
           bbbbb
  Description:
  stuff

  $ ./linux-2.6.6-rc2/scripts/kernel-doc -text test.c
  struct stuff:
  struct stuff {
          int a;
          char b;
  };
  Members:
  a
           aaaa
  b
           bbbbb
  Description:
  stuff

From: Rusty Russell <rusty@rustcorp.com.au>

From:  "Chen, Kenneth W" <kenneth.w.chen@intel.com>

Pure cosmetic.  Largest biovec slab is printed as biovec-BIO_MAX_PAGES in
/proc/slabinfo.  It would be more informative to print actual number instead
of macro's name.

From: Nuno Monteiro <nuno@itsari.org>

Remove lots of double-semicolons.

From: Neil Brown <neilb@cse.unsw.edu.au>

If a single readdir entry needs to be split over two pages in the reply, we
first encode it into a new page, and then copy the bits into place.  When
we do this relocation, we have to modify the "offset" pointer to be either
in the first or the second page, as appropriate.

If the pointer should be at the start of the second page, it is currently
put past the end of the first page.

Note that as the offset and whole response is known to be 4byte-aligned,
the offset pointer will never be split over two pages.

From: David Mosberger <davidm@napali.hpl.hp.com>

These aren't syscalls, so rename them.  And make them static.

We keep on getting BUG()s from isofs_read_super() because it passes an insane
blocksize to bread().  See http://bugme.osdl.org/show_bug.cgi?id=2735 for
example.

I don't know what's up with isofs, but going BUG in there seems a bit rude.
Change it to drop a bunch of diagnostics and a backtrace then return a null
bh*.

Most callers of getblk() don't expect it to fail, so they'll oops anyway.  But
isofs does actually check for a NULL return.  This way, the machine stays up
and we get better debug diagnostics.

From: Rusty Russell <rusty@rustcorp.com.au>

kallsyms contains only function names, but some debuggers (eg.  xmon on
PPC/PPC64) use it to lookup symbols: it'd be much nicer if it included data
symbols too.

Give appropriate and separate backing_dev_info's to both the ramdisk blockdev
inode and to the files which live atop the ramdisk.

Everything works now.

Implement an empty ->writepages() so that attempts to write back ramdisk pages
have less work to do.

When a filesystem does getblk() to get a buffer_head against the ramdisk the
VFS will allocate a new not-uptodate pagecache page and will attach buffers to
it.

The filesystem will then bring certain buffer_heads uptodate.  But not the
whole page.

Later, various ramdisk a_ops see the not-uptodate page and wipe the whole
thing out, including the parts to which the filesystem wrote!

Fix that up by only zapping those parts of the page which are covered by
non-uptodate buffers.

We don't actualy need to kmap the blockdev inode's pages at all, because
they're ~__GFP_HIGHMEM.  But it's future-safe, and cheap.

There's a race: one CPU writes a 1k block into a ramdisk page which isn't in
the blockdev pagecache yet.  It memsets the locked page to zeroes.

While this is happening, another CPU comes in and tries to write a different
1k block to the "disk".  But it doesn't lock the page so it races with the
memset and can have its data scribbled over.

Fix this up by locking the page even if it already existed in pagecache.

Locking a pagecache page in a make_request_fn sounds deadlocky but it is not,
because:

a) ramdisk_writepage() does nothing but a set_bit(), and cannot recur onto
   the same page.

b) Any higher-level code which holds a page lock is supposed to be
   allocating its memory with GFP_NOFS, and in 2.6 kernels that's equivalent
   to GFP_NOIO.

   (The distinction between GFP_NOIO and GFP_NOFS basically disappeared
   with the buffer_head LRU, although it was reused for writes to swap).

Allocating pagecache pages within the disk request_fn is deadlocky and prone
to page allocation failures, causing write I/O errors.

Attempt to improve things by fiddling with gfp masks.

- Remove the ramdisk special-case in fs-writeback.c - it will soon be
  unneeded.

- Fix rd_ioctl() to return -ENOTTY on invalid ioctl types, not -EINVAL.

- Make ramdisk Kconfig friendlier.

From: Paul Mackerras <paulus@samba.org>

We declare enter_rtas with a struct rtas_args * argument, though it is
supposed to be a physical address, and then every time we call it we cast the
unsigned long result from __pa() to a void *.  This patch changes the
declaration of enter_rtas to make it take an unsigned long argument, and
removes the cast from all the callers.  The actual enter_rtas() routine is in
assembler and doesn't need to be changed.

From: David Gibson <david@gibson.dropbear.id.au>

The ppc64 head.S contains an enable_32b_mode function which is used
nowhere.  This patch removes it.

From: Paul Mackerras <paulus@samba.org>

This patch fixes a whole pile of problems in the xmon kernel debugger for
ppc64.  This basically makes xmon SMP-safe.  Now, when we enter xmon it
sends an IPI to the other CPUs to get them into xmon too.  It also changes
the way we do single-stepping and breakpoints so that we don't have to
remove a breakpoint to proceed from it (instead we either emulate the
instruction where the breakpoint was, or execute it out of place).  With
this patch, if we get an exception inside xmon, it will just return to the
xmon command loop instead of hanging the system as at present.

The patch is quite large because it updates the disassembler to the latest
version from binutils (trimmed a bit), which is why I didn't cc lkml.