The request queue was increased from 256 slots to 512 in 2.5.20.  The
throughput of `dbench 128' on Randy's 384 megabyte machine fell 40%.

We do need to understand why that happened, and what we can learn from
it.  But in the meanwhile I'd suggest that we go back to 256 slots so
that this known problem doesn't impact people's evaluation and tuning
of 2.5 performance.

mark_buffer_dirty() is showing up on Anton's graphs.  Avoiding the
buslocked RMW if the buffer is already dirty should fix that up.

- If grab_cache_page_nowait() is to be called while holding a lock on
  a different page, it must perform memory allocations with GFP_NOFS.
  Otherwise it could come back onto the locked page (if it's dirty) and
  deadlock.

  Also tidy this function up a bit - the checks in there were overly
  paranoid.

- In a few of places, look to see if we can avoid a buslocked cycle
  and dirtying of a cacheline.

Remove unneeded do_update_atime(), and convert update_atime() to C.

Stephen and Neil Brown recently worked this out.  It's a
rare situation which only affects data=journal mode.

Fix problem in data=journal mode where writeback could be left pending on a
journaled, deleted disk block.  If that block then gets reallocated, we can
end up with an alias in which the old data can be written back to disk over
the new.  Thanks to Neil Brown for spotting this and coming up with the
initial fix.

Adds five sysctls for tuning the writeback behaviour:

	dirty_async_ratio
	dirty_background_ratio
	dirty_sync_ratio
	dirty_expire_centisecs
	dirty_writeback_centisecs

these are described in Documentation/filesystems/proc.txt  They are
basically the tradiditional knobs which we've always had...

We are accreting a ton of obsolete sysctl numbers under /proc/sys/vm/.
I didn't recycle these - just mark them unused and remove the obsolete
documentation.

Ironically enough, both were written by me.

Fixed thus.

Add change_page_attr to change page attributes for the kernel linear map.

Fix AGP driver to use change_page_attr for the AGP buffer.

Clean up AGP driver a bit (only tested on i386/VIA+AMD)

Change ioremap_nocache to use change_page_attr to avoid mappings with
conflicting caching attributes.

This exports the pci_bus_type symbol to modules, needed by (at least)
the recent changes in pcmcia/cardbus.c.

This was done by inspection, is it OK Anton?  It's very simple:

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

This patch removes the concept of "logical" CPU numbers, in
preparation for CPU hotplugging.

Summary: 2.5.17 broke initrd on x86. Fix below.

Why: Kai's patch in 2.5.17 to move x86-specific options from
Makefile to arch/i386/boot/Makefile unfortunately lost the fact
that the orginal "#export RAMDISK = -DRAMDISK=512" statement
was commented out. (I suspect a typo.) RAMDISK is obsolete since
1.3.something, and uncommenting it has "interesting" effects
since the ram_size field has a very different meaning now.

The patch below reverts the statement to its pre-2.5.17 state.
Perhaps it should be removed altogether?

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

This patch splits fput into fput and __fput.  __fput is needed by aio to
construct a mechanism for performing a deferred fput during io
completion, which typically occurs during interrupt context.

This adds support for wait queue function callbacks, which are used by
aio to build async read / write operations on top of existing wait
queues at points that would normally block a process.

This patch switches SCSI from a bottom half to a tasklet.  It's been
reviewed, tested & approved by Andrew Morton, James Bottomley & Doug
Gilbert.

I took a quick look at why 2.5.21 hung at boot detecting partitions,
because a 2.5.22 did the exact same thing on my test box today... The
tcq locking is completely screwed now, and as I said before the weekend
I think the entire locking is just getting worse now.

Anyways, this patch at least attempts to make tcq follow the channel
lock usage to make it work for me.

Attached patch brings over the sane bits from 2.4-ac: i.e. if Linus
merges this and Alan merges your patch minus my complaints, the two
trees will be in sync...

 - Finally unify task_in_intr and task_mulin_intr. One crucial code path less to
   watch out, but a quite dangerous step in itself. PIO reading is functional
   again. The next step will be the unification of the write path of course.

 - Introduce a small helper for the execution of task file commands which
   basically just send a simple command down to the drive.

 - Add a buffer parameter to ide_raw_taskfile allowing to unify the handling of
   ioctl and normal ide_raw_taskfile request.

 - Fix some small function pointer type mismatches.

Apply more host chip controller clenups by Bartlomiej:

     - move setting drive->current_speed from *_tune_chipset()
       to ide_config_drive_speed()

    cmd64x.c:
	- convert cmd64x_tuneproc() to use ata-timing library
	- clean cmd64x_tune_chipset() and cmd680_tune_chipset()

    hpt366.c:
	- remove empty timings table

    it8172.c:
	- kill prototypes
	- update to new udma_setup() scheme

    - misc cleanups

  Set up CardBus cards correctly: initialize them fully
  before calling device_register(), and make sure to tell
  the world that it's a PCI-like bus.

This kills Sysrq-D support (did not work anyway, and complicated
code).

Adds resume support to i8259A (otherwise interrupts will not work
after S3).

HAVE_NEW_DEVICE_MODEL is always true in 2.5, so we should define
it. S3 can't work properly without that. Also limit toshiba workaround
to S1. (This hide lack of i8259A support for me).

Fixes compilation, and kills <asm/suspend.h> being included
twice with ugly hacks around.

- (leak) memory allocated in dscc4_found1() isn't freed by caller in error path.
  dscc4_free1() is now in charge of this duty.
- (style) code factored in dscc4_remove_one after use of dscc4_free1().

- (compilation fix) plain old typo in struct member naming.

- (compilation fix) missing init.h include;
- (compilation fix) multiple pointers can't be set to NULL in one line if their
  type differ.

Courtesy of Kevin Curtis <kevin.curtis@farsite.co.uk>, posted
on l-k the 2002/04/15.

Description
- (compilation fix) removal of deprecated fields in net_device;
- (bug) early pci_enable_device.