Fixes a few lock ranking bugs (and deadlocks) related to
swap_list_lock(), swap_device_lock(), mapping->page_lock and
mapping->private_lock.

- Cannot call block_flushpage->try_to_free_buffers() inside
  mapping->page_lock.  Because __set_page_dirty_buffers() takes
  ->page_lock inside ->private-lock.

- Cannot call swap_free->swap_list_lock/swap_device_lock inside
  mapping->page_lock because exclusive_swap_page() takes ->page_lock
  inside swap_info_get().


The patch also removes all the block_flushpage() calls from the swap
code in favour of a direct call to try_to_free_buffers().

The theory is that the page is locked, there is no I/O underway, nobody
else has access to the buffers so they MUST be freeable.  A bunch of
BUG() checks have been added, and unless someone manages to trigger
one, the "block_flushpage() inside spinlock" problem is fixed.

Give swapper_space a ->set_page_dirty() address_space_operation.

So swapcache pages do not need special-casing in
set_page_dirty_buffers().

Turn on direct-to-BIO writeback for ext3 in data=writeback mode.

block_symlink() is not a "block" function at all.  It is a pure
pagecache/address_space function.  Seeing driverfs calling it was
the last straw.

The patch renames it to `page_symlink()' and moves it into fs/namei.c

Remove i_wait from struct inode and hash it instead.

This is a pure space-saving exercise - 12 bytes from struct
inode on x86.

NFS was using i_wait for its own purposes.  Add a wait_queue_head_t to
the fs-private inode for that.  This change has been acked by Trond.

Implement buffer_boundary() for ext3.

buffer_boundary() is an I/O scheduling hint which the filesystem's
get_block() function passes up to the BIO assembly code.  It is
described in fs/mpage.c

The time to read 1,000 52 kbyte files goes from 8.6 seconds down to 2.9
seconds.  52 kbytes is the worst-case size.

Speeds up generic_file_write() by not calling mark_inode_dirty() when
the mtime and ctime didn't change.

There may be concerns over the fact that this restricts mtime and ctime
updates to one-second resolution.  But the interface doesn't support
that anyway - all the filesystem knows is that its dirty_inode()
superop was called.  It doesn't know why.

So filesystems which support high-resolution timestamps already need to
make their own arrangements.  We need an update_mtime i_op to support
those properly.

time to write a one megabyte file one-byte-at-a-time:

Before:
	ext3:		24.8 seconds
	ext2:		 4.9 seconds
	reiserfs:	17.0 seconds
After:
	ext3:		22.5 seconds
	ext2:		4.8  seconds
	reiserfs:	11.6 seconds

Not much improvement because we're also calling expensive
mark_inode_dirty() functions when i_size is expanded.  So compare the
overwrite case:

time dd if=/dev/zero of=foo bs=1 count=1M conv=notrunc

ext3 before:	20.0 seconds
ext3 after:	9.7  seconds

First some terminology: this patch introduces a kernel-wide `pgoff_t'
type.  It is the index of a page into the pagecache.  The thing at
page->index.  For most mappings it is also the offset of the page into
that mapping.  This type has a very distinct function in the kernel and
it needs a name.  I don't have any particular plans to go and migrate
everything so we can support 64-bit pagecache indices on x86, but this
would be the way to do it.

This patch improves the packing density of swapcache pages in the radix
tree.

A swapcache page is identified by the `swap type' (indexes the swap
device) and the `offset' (into that swap device).  These two numbers
are encoded into a `swp_entry_t' machine word in arch-specific code
because the resulting number is placed into pagetables in a form which
will generate a fault.

The kernel also need to generate a pgoff_t for that page to index it
into the swapper_space radix tree.  That pgoff_t is usually
bitwise-identical to the swp_entry_t.  That worked OK when the
pagecache was using a hash.  But with a radix tree, it produces
catastrophically bad results.

x86 (and many other architectures) place the `type' field into the
low-order bits of the swp_entry_t.  So *all* swapcache pages are
basically identical in the eight low-order bits.  This produces a very
sparse radix tree for swapcache.  I'm observing packing densities of 1%
to 2%: so the typical 128-slot radix tree node has only one or two
pages in it.

The end result is that the kernel needs to allocate approximately one
new radix-tree node for each page which is added to the swapcache.  So
no wonder we're having radix-tree node exhaustion during swapout!
(It's actually quite encouraging that the kernel works as well as it
does).

The patch changes the encoding of the swp_entry_t so that its
most-significant bits contain the `type' field and the
least-significant bits contain the `offset' field, right-aligned.

That is: the encoding in swp_entry_t is now arch-independent.  The new
file <linux/swapops.h> has conversion functions which convert the
swp_entry_t to and from its machine pte representation.

Packing density in the swapper_space mapping goes up to around 90%
(observed) and the kernel is tons happier under swap load.


An alternative approach would be to create new conversion functions
which convert an arch-specific swp_entry_t to and from a pgoff_t.  I
tried that.  It worked, but I liked it less.

Remove some unused PageSkip() macros.  Presumably leftovers from
PG_skip which isn't there any more.

A common and very subtle bug is to use list_heads which aren't on any
lists.  It causes kernel memory corruption which is observed long after
the offending code has executed.

The patch nulls out the dangling pointers so we get a nice oops at the
site of the buggy code.

I missed this one in the last patch I sent to you.

Too much copy'n paste between 2.4 and 2.5 code base, attached patch on
top of the previous block tag fixes makes it work/compile again. Sorry
about that.

A buglet and a few adjustments.

This should be the last of tq_disk, at least the trivial ones. md still
has some queue_task references, I'll let Ingo/Neil clean those up.
suspend is still broken, it was broken before too though. I guess Pavel
will want to fix that.

Also, I've documented the plug functions.

 - PPC compilation fix by Paul Mackerras.

 - Various fixes by Bartek:

   fix ata_irq_enable() and ata_reset() for legacy ATA-1 devices

   in start_request() for REQ_DRIVE_ACB
   a) don't run ->prehandler() twice
   b) return ata_taskfile() value

 - Don't use ata_taskfiles cmd field for drive status reporting,
   we can now simply use drive->status instead.

 - Unify command type parser entries which could be unified due to the
   unification of corresponding interrupt handlers.

 - Eliminate reading parameter from ata_do_udma(). We have this information
   already in the rq. This allows us to merge several methods.

 - Rename XXX_udma to udma_setup, since we have finally settled up on this
   semantics.

 - Simplify tons of host chip code by removing wrapper functions.

 - Sanitize the handling of the ioctl's and fix a bug on the way in dealing with
   the WIN_SMART command where arguments where exchanged.

 - Finally sanitize ioctl further until it turned out that we could get rid of
   the special request type REQ_DRIVE_CMD entierly. We are now using
   consistently REQ_DRIVE_ACB.

   One hidden code path less again!

 - Realize the ide_end_drive_cmd can be on the REQ_DRIVE_ACB only for ioctl() to
   a disk. Eliminate it's usage from device type driver modules.

 - Remove command member from struct  hd_drive_task_hdr and place it in strcut
   ata_taskfile. It is not common between the normal register file and HOB.

   We will have to introduce some helper functions for particular command types.

 - Fix typo in sparc_v9 code, in ns87415, just introduced.

 - Eliminate unnecessary struct hd_drive_hob_hdr those are
   in reality precisely the same registers as usual.

 - Eliminate control_t, nowhere used type.

 - Unfold ide_init_drive_cmd() at the places where it's used. This makes obvious
   that REQ_DRIVE_CMD gets only used on the ioctl command path.

 - Move ide_fixstring() from ide.c to probe.c, since this is the place, where it's
   most used.

 - Remove GET_STAT() - it's not used any longer.

 - Remove last parameter of ide_error. Rename it to ata_error().

 - Don't use ide_fixstring in qd65xx.c host chip driver. The model name is
   already fixed in probe.c.

 - Invent ata_irq_enable() for the handling of the trice nIEN bit of the
   control register.  Consistently use ch->intrproc method every time we toggle
   this bit.  This simply wasn't the case before!

 - Disable interrupts on a previous channel only when we share them indeed.

 - Eliminate simple drive command handling function drive_cmd.

 - Simplify the ioctl handler. Move it to ioctl, since that's the only place
   where it's actually used.

as it isn't even all that big.

  David Mosberger added argument page to clear_user_page, but
apparently did not scan whole tree to find callers. Please apply.
It's the only such call in the non-arch specific portion of tree.

 - Get rid of SELECT_DRIVE macro. Start to move all direct hardware access
   functions in to one place.

 - Get rid of SELECT_MASK macro. Realize that the mask is always equal 0.
   Simplify the maskproc therefore.

 - Get rid of GET_STAT and OK_STAT macros as well.

 - hpt366 cleanups by Andrej Panin.

 - Artop driver update by Franz Sirl.

into home.transmeta.com:/home/torvalds/v2.5/linux

folks, and the ARM people didn't mind.

into penguin.transmeta.com:/home/penguin/torvalds/repositories/kernel/linux

* support latest wireless extensions
* update locking to use semaphores

into mandrakesoft.com:/home/jgarzik/repo/net-drivers-2.5

Here's my last and final patch to the maintainer of USB Scanner Driver.  Brian
Beattie <beattie@beattie-home.net> is now going to assume this role (thanks
Brian!).  Brian brings some kernel level programming so I'm sure he'll be able
to conttribute to this list w/o any problems.  I want to thank you all for your
support and help.  A couple of you sent some personal msgs regarding my
departure - thank you.

* 0.4.8  5/30/2002
 *    - Added Mustek BearPaw 2400 TA.  Thanks to Sergey
 *      Vlasov <vsu@mivlgu.murom.ru>.
 *    - Added Mustek 1200UB Plus and Mustek BearPaw 1200 CU ID's.  These use
 *      the Grandtech GT-6801 chip. Thanks to Henning
 *      Meier-Geinitz <henning@meier-geinitz.de>.
 *    - Increased Epson timeout to 60 secs as requested from
 *      Karl Heinz Kremer <khk@khk.net>.
 *    - Changed maintainership from David E. Nelson to Brian
 *      Beattie <beattie@beattie-home.net>.

I just noticed a debug message will generate a needless warning
when debugging is disabled.

updated the kernel-api documentation USB files due to file reorg.

The patch below adds first round of AGP support for the Intel 460
chipset

This won't actually build at the moment, but I think you prefer to
merge things piecemeal, and this portion of the patch is almost
guaranteed to be safe (affects only ia64).

GCC3.1 apparently gets confused about uninitialized sections

Hi Linus,

Are you willing to change the interfaces of clear_user_page() and
copy_user_page() so that they can receive the relevant page pointer as
a separate argument?  I need this on ia64 to implement the lazy-cache
flushing scheme.

I believe PPC would also benefit from this.

	--david

On ia64 MP machines, we use the cycle counter register of each CPU to
obtain fine-grained time-stamps.  At boot-time, we synchronize the
counters as close as possible (similar to x86, though with a different
algorithm).  But even with this synchronization, there is still a
small (really: tiny) chance that a process bouncing from one CPU to
another could observe time going backwards.  To guard against this, I
maintain a global variable called "last_time_offset" which keeps track
of the largest time-interpolation value returned so far.  Most of this
is in platform-specific code (arch/ia64/kernel/time.c), but there are
a handful of places in platform-independent code where this variable
needs to be cleared to zero.  This is what the patch below does.  I
didn't put it inside CONFIG_IA64 because I think this can be useful
for other platforms, too.  I suppose I could put it inside CONFIG_SMP
though this would make the code uglier.  If you think it's OK, please
apply, otherwise, I'd appreciate your feedback.

This makes it possible to run the ia64 kernel both on platforms with the
legacy keyboard controller and those without (as is the case for the hp
zx1 platform, for example).  The new code is inside #ifdef CONFIG_IA64,
though it would probably be a good idea to enable it unconditionally.
The patch is by Alex Williamson.

into penguin.transmeta.com:/home/penguin/torvalds/repositories/kernel/linux

stuff.