from Andreas Gruenbacher

Patch from Maneesh Soni <maneesh@in.ibm.com>, Dipankar Sarma
<dipankar@in.ibm.com> and probably others.


This patch provides dcache_lock free d_lookup() using RCU. Al pointed
races with d_move and lockfree d_lookup() while concurrent rename is
going on. We tested this with a test doing million renames
each in 50 threads on 50 different ramfs filesystems. And simultaneously
running millions of "ls". The tests were done on 4-way SMP box.

1. Lookup going to a different bucket as the current dentry is
   moved to a different bucket due to rename. This is solved by
   having a list_head pointer in the dentry structure which points
   to the bucket head it belongs. The bucket pointer is updated when the
   dentry is added to the hash chain. Lookup checks if the current
   dentry belongs to a different bucket, the cached lookup is
   failed and real lookup will be done. This condition occured nearly
   about 100 times during the heavy_rename test.

2. Lookup has got the dentry it is looking and it is comparing
   various keys and meanwhile a rename operation moves the dentry.
   This is solved by using a per dentry counter (d_move_count) which
   is updated at the end of d_move. Lookup takes a snapshot of the
   d_move_count before comparing the keys and once the comparision
   succeeds, it takes the per dentry lock to check the d_move_count
   again. If move_count differs, then dentry is moved (or renamed)
   and the lookup is failed.

3. There can be a theoritical race when a dentry keeps coming back
   to original bucket due to double moves. Due to this lookup may
   consider that it has never moved and can end up in a infinite loop.
   This is solved by using a loop_counter which is compared with a
   approximate maximum number of dentries per bucket. This never got
   hit during the heavy_rename test.

4. There is one more change regarding the loop termintaion condition
   in d_lookup, now the next hash pointer is compared with the current
   dentries bucket pointer (is_bucket()).

5. memcmp() in d_lookup() can go out of bounds if name pointer and length
   fields are not consistent. For this we used a pointer to qstr to keep
   length and name pointer in one structre.

We also tried solving these by using a rwlock but it could not compete
with lockless solution.

Patch from Maneesh Soni <maneesh@in.ibm.com>

Revert the fast-walk dcache code in preparation for dcache_rcu.

Patch from Joakim Tjernlund <joakim.tjernlund@lumentis.se>

I did the optimizations in the crc32 patch Brian Murphy submitted a while ago.
Now I have cleaned it up a little and made some more optimizations.

gcc is quite bad at loop optimizations (at least for PPC) so I have
rewritten them to make gcc to generate better code. Even recent gcc's(3.2.x) produces
better code.

Also reduced the unrolling since it did not make a noticeable difference.

When ext3_writepage races with truncate, block_write_full_page() will see
that the page is outside i_size and will bale out with -EIO.  But
ext3_writepage() will ignore this and will proceed to add the buffers to the
transaction.

Later, kjournald tries to write them out and goes BUG() because those buffers
are not mapped to disk.

The fix is to not attach the buffers to the transaction in ext3_writepage()
if block_write_full_page() failed.

So far so good, but that page now has dirty, unmapped buffers (the buffers
were attached in a dirty state by ext3_writepage()).  So teach
block_write_full_page() to clean the buffers against the page if it is wholly
outside i_size.

(A simpler fix to all of this mught be to just bale out of ext3_writepage()
if the page is outside i_size.  But that is racy against
block_write_full_page()'s subsequent execution of the same comparison).

Patch from: Oleg Drokin <green@namesys.com>

It moves all the arg checking code from the start of generic_file_aio_write()
into a standalone function, so other filesystems can avoid having to
cut-n-paste them.

The new function is exported to modules, and also inlined in filemap.c so
that the current filesystems are unaffected.  If someone is using ext2 and
reiserfs at the same time, they lose a bit of icache.

Patch from Oleg Drokin <green@namesys.com>

Move these already-inline functions to a header file so that filesystems can
reuse them.  For the reiserfs_file_write patch.

Patch from: Zwane Mwaikambo <zwane@holomorphy.com>

Considering that smp_call_function isn't allowed to hold a lock reference and
within smp_call_function we lock and unlock call_lock thus triggering a
preempt point.  Therefore we can't guarantee that we'll be on the same
processor when we hit do_flush_tlb_all_local.

void flush_tlb_all(void)
{
	smp_call_function (flush_tlb_all_ipi,0,1,1);

	do_flush_tlb_all_local();
}

...

smp_call_function()
{
	spin_lock(call_lock);
	...
	spin_unlock(call_lock);
	<preemption point>
}

...

do_flush_tlb_all_local() - possibly not executing on same processor
anymore.

I'm getting a build error:

	fs/jfs/super.c: In function `jfs_fill_super':
	fs/jfs/super.c:335: parse error before `)'

and it doesn't happen with gcc-3.2.x.

Taking out the file-n-line fixes it up.  This patch was acked by shaggy.

Robbie Williamson found some bugs in the mandatory locking implementation.
This patch fixes all the problems he found:

 - Fix null pointer dereference caused by sys_truncate() passing a null filp.
 - Honour the O_NONBLOCK flag when calling ftruncate()
 - Local variable `fl' wasn't being initialised correctly in
   locks_mandatory_area()
 - Don't return -ENOLCK from __posix_lock_file() when FL_ACCESS is set.

We must grab lock before checking rl->count.

bio-to-request front merging works, but request-to-request has been
broken due to a bit too much copy'n pasting.

Cleaner fix for the ioscheduler:

- Problem with alias request, the new request gets lost.
- Must always clear merge hash in move_to_dispatch()

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

into redhat.com:/garz/repo/net-drivers-2.5

Just approving this as maintainer of i2o_scsi

This lets me put mca-legacy into drivers to fix them for now without
worrying about losing the fact they want more attention

There are no known cards outside of labs that used i2o_lan. The only
exception is the Redcreek VPN, which has its own driver anyway. Note
i2o_lan.h is left as i2o_config can still understand i2o_lan devices
such as the RedCreek.

The following patches should fix those last two issues - compiling boot.c
for UP and compiling proc.c by default.

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

  This is needed because mark_buffer_dirty is now checking if buffer is up to date.
  Noticed by Alex Tomas <bzzz@tmi.comex.ru>

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

into tetrachloride.(none):/mnt/stuff/kernel/2.5/cpufreq

into tetrachloride.(none):/mnt/stuff/kernel/2.5/agpgart