- Add some commentary to this function

- Add a mutex to prevent new callers of sync_filesytems() from DoSing
  currently-running caller.

From: Dipankar Sarma <dipankar@in.ibm.com>

This patch makes the list macros use smp-only version of the barriers,
no need to hurt UP performance.

ext3_writepage() calls ext3_journal_stop(), which dereferences the affected
inode.

It does this _after_ writing the page out, which is illegal.  The IO can
complete, the page can be repeased from the inode and the inode can be freed
up.

It's a long-standing bug.  It has been reported happening on preemptible
kernels, where the timing window is larger.

Fix that up by teaching ext3_journal_stop to locate the superblock via the
journal structure, not via the inode.

This means that ext3_journal_stop() does not need the inode argument at all.

Also uninline the affected functions.  It saves 5.5 kbytes.

Also remove the setting of sb->s_dirt in ext3_journal_stop().  That was an
awkward way of telling sys_sync() that the filesystem needs a commit, and
with the ext3_sync_fs() that is no longer needed.

From: Alex Tomas <bzzz@tmi.comex.ru>

This is the second half of the vm_enough_memory() speedup.

When overcommit_memory != 1, vm_enough_memory() calls get_page_state() to
calculate the amount of used pagecache.  It does this on every call to
sys_brk().

get_page_state() is really expensive on SMP.

So the patch arranges for pagecache accounting to be in a global atomic_t,
with per-cpu batching and approximate accounting to amortise the cost of the
global atomic.

The nr_pagecache field of /proc/vmstat is removed.

From: george anzinger <george@mvista.com>

The recently-added code which avoids a lockup when a timer handler re-adds
the timer right now can be simplified.

If we change __run_timers() to increment base->timer_jiffies _before_ running
the timers, then any re-additions will not be inserted in the list which
__run_timers is presently walking.

From: george anzinger <george@mvista.com>

Remove the `index' field from the timer structures.  It contains the same
info as the timer_jiffies field.

So just use the base->timer_jiffies field directly.

Patch from Andries.Brouwer@cwi.nl

The third patch removes the last occurrences of MAX_BLKDEV and MAX_CHRDEV and
sorts the majors in major.h.  It also updates the definition of
SCSI_DISK_MAJOR.

Patch from Andries.Brouwer@cwi.nl

The actual patch for today is this part.  I already quoted most of this on
the list earlier this week.

In order not to have to change all drivers, I did

+int register_chrdev(unsigned int major, const char *name,
+                   struct file_operations *fops)
+{
+       return register_chrdev_region(major, 0, 256, name, fops);
+}

so that the old register_chrdev registers a single major and 256 minors.
Later this can be changed (but see my letter to Al last week).

The only driver that is tricky is the tty driver.  Here some major cleanup
happened - all tty specific stuff disappeared from char_dev.c, and tty uses
the actual register_chrdev_region() call.

There is a race in register_chrdev_region() that I did not worry about: when
two dynamic majors 0 are registered simultaneously, one of them will be first
and the other one gets -EBUSY.  If this is a problem, the code there will
have to be uglified a little.  I didn't do that because it disappears again
in a subsequent patch.

Patch from Andries.Brouwer@cwi.nl

Now that 2.5.65 is out, the next dev_t patch.  It was a bit large and
unreadable, so I split it into three clean pieces.  Afterwards, since many
people ask for this, a fourth patch that actually changes the type of dev_t
(not to be applied yet, that is just for playing).

The first patch is the cdev-kill patch that I sent out earlier.  It is no use
having two forms of chardev registration in the source, and my version of the
path of small modifications does not pass through this version, although the
final result will not be that different.  So, kill cdev_cachep,
cdev_cache_init, cdfind, cdget, cdput, inode->i_cdev, struct char_device.
All of this is dead code today.

The second patch removes MAX_CHRDEV.

The third patch polishes linux/major.h.

The mwave driver oopses if you do not have the hardware installed.  It is
running device_unregister() and device_remove_file() against things whch were
never created.

bdevname returns a pointer to a static string.  Change it so that the caller
passes in the buffer.

- It was racy, if two threads try to register a blockdev with major=0 they
  could both choose the same major for different devices.

  Fix that by extending the coverage of the rwsem.

- kmalloced local variable `p' was leaking on an error path.

This function was recently converted to use rwsem locking.  But it is called
from interrupts in (at least) buffer_io_error().

And we do want a function like this to be robust and atomic.  So convert it
to use spinlocking.

Filesystems which are using generic_file_llseek() do not need lock_kernel()
in their readir implementations.  All operations (including llseek) are
serialised by the directory's i_sem.

Just fix ext2 and ext3 for now.  Others may need locking between readdir and
who-knows-what.

This function is called a lot.  Every brk().  The atomic_add() against a
global counter hurts on large SMP machines.

The patch simply reduces the rate at which that atomic operation is
performed, by accumulating a per-cpu count which is spilled into the global
counter when the local counter overflows.

It trades off efficiency for a little inaccuracy.

I tried various implementations involving kmalloc_percpu() and open-coded
per-cpu arrays in a generic "per-cpu counter" thing.  They all were
surprisingly sucky - the additional cache misses involved in walking the more
complex data structures really showed up.

vmtruncate() does not need lock_kernel().  And lock_kernel() is not taken by
other vmtruncate() callers.

Turn on MS_ONE_SECOND in ext2 and ext3.

For some filesystems (ext3, reiserfs at least), ->dirty_inode() is very
expensive.  The kernel is currently calling mark_inode_dirty() at up to 1000
times/sec/inode.  But there is no need to do this if the filesystem cannot
store high-resolution times on-disk.

This patch restores the optimisation of only dirtying the filesystem inode
when its on-disk representation has actually changed.

The filesystem will set the MS_ONE_SECOND flag in sb->s_flags to indicate
that it wishes to receive this treatment.

The patch does reduce the call rate to ext3_mark_inode_dirty() from 1000/sec
to 1/sec, but it doesn't make much difference at all to performance because
we're calling ext3_mark_inode_dirty() from other callsites as well.  Those
can be optimised too.

ppc64 support for file file-offset-in-pte

Path from Andi Kleen <ak@muc.de>

Add x86_64 support for file offsets in pte's.

filemap_populate() is currently doing page-at-a-time synchronous I/O.  Add a
call to do_page_cache_readahead() in there so we do a big slurp of IO first.

This is minimal - a lot of the filemap_populate() code can be
rationalised yet.

This patch requires arch support.  I have patches for ia32, ppc64 and x86_64.
Other architectures will break.  It is a five-minute fix.  See

	http://mail.nl.linux.org/linux-mm/2003-03/msg00174.html

for implementation details.


Patch from: Ingo Molnar <mingo@elte.hu>

the attached patch, against BK-curr, is a preparation to make
remap_file_pages() usable on swappable vmas as well.  When 'swapping out'
shared-named mappings the page offset is written into the pte.

it takes one bit from the swap-type bits, otherwise it does not change the
pte layout - so it should be easy to adapt any other architecture to this
change as well.  (this patch does not introduce the protection-bits-in-pte
approach used in my previous patch.)

On 32-bit pte sizes with an effective usable pte range of 29 bits, this
limits mmap()-able file size to 4096 * 2^29 == 2 TBs.  If the usable range is
smaller, then the maximum mmap() size is reduced as well.  The worst-case i
found (PPC) was 2 hw-reserved bits in the swap-case, which limits us to 1 TB
filesize.  Is there any other hw that has an even worse ratio of sw-usable
pte bits?

this mmap() limit can be eliminated by simply not converting the swapped out
pte to a file-pte, but clearning it and falling back to the linear mapping
upon swapin.  This puts the limit into remap_file_pages() alone, but i really
hope no-one wants to use remap_file_pages() on a 32-bit platform, on a larger
than 1-2 TB file.

sys_remap_file_pages() is now enforcing the 'prot' parameter to be zero.
This restriction might be lifted in the future - i really hope we can have
more flexible remapping once 64-bit platforms are commonplace - eg.  things
like memory debuggers could just use the permission bits directly, instead of
creating many small vmas.

i've tested swappable nonlinear ptes and they are swapped out/in
correctly.

some other changes in -A0 relative to 2.5.63-BK:

 - slightly smarter TLB flushing in install_page(). This is still only a
   stupid helper functions - a more efficient 'walk the pagecache tree
   and pagetable at once and use TLB-gather' implementation is preferred.

 - cleanup: pass on pgprot_t instead of unsigned long prot.

 - some sanity checks to make sure file_pte() rules are followed.

 - do not reduce the vma's default protection to PROT_NONE when using
   remap_file_pages() on it. With swappable ptes this is now safe.

This patch fixes a couple of bugs and compile errors in the powerbook
media bay driver.  It was getting initialized after the IDE subsystem,
whereas it needs to be initialized before so that the IDE subsystem
can see the CD-ROM drive in the bay.

This patch updates the mac53c94 scsi HBA driver, used on older
powermacs, to correspond with the recent scsi subsystem changes, to
use the PCI DMA API, to not panic, and to use a spinlock instead of
save_flags/restore_flags/cli/sti.

This patch updates the `mesh' scsi driver used on older powermacs to
correspond with recent changes in the scsi subsystem (things like
using cmd->device->id instead of cmd->target).

This patch forward-ports various fixes to the driver for the PMU
(power manager unit) on powermacs and powerbooks from 2.4, and in
particular, some improvements to the battery charge calculations.

From Ben Herrenschmidt.

The patch below removes the uses of save_flags/restore_flags/cli
etc. from the macserial driver and replaces them with a spinlock.

This patch updates the CUDA driver (the power/reset/ADB controller on
older powermacs) to fix some SMP issues and to match the 2.4 version
of the driver.

From Ben Herrenschmidt.

This patch updates include/linux/adb.h and include/linux/pmu.h with
some additional definitions that we need on powermacs and powerbooks.

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

into samba.org:/home/paulus/kernel/for-linus-ppc

into samba.org:/home/paulus/kernel/for-linus-ppc

Convert the pcnet_cs driver to use the new registration call.

Remove the linked list of pcmcia_drivers. It didn't even handle removal of a
driver properly, so it won't be missed all that much.

Register all pcmcia drivers with the pcmcia bus within the old
register_pccard_driver() function. Alternatively, a new
registration function "pcmcia_register_driver()" (and its
counterpart,  "pcmcia_unregister_driver()") can be used.