Two fixes here.

First:

Fixes a BUG() which occurs if you try to perform O_DIRECT IO against a
blockdev which has an fs mounted on it.  (We should be able to do
that).

What happens is that do_invalidatepage() ends up calling
discard_buffer() on buffers which it couldn't strip.  That clears
buffer_mapped() against useful things like the superblock buffer_head.
The next submit_bh() goes BUG over the write of an unmapped buffer.

So just run try_to_release_page() (aka try_to_free_buffers()) on the
invalidate path.


Second:

The invalidate_inode_pages() functions are best-effort pagecache
shrinkers.  They are used against pages inside i_size and are not
supposed to throw away dirty data.

However it is possible for another CPU to run set_page_dirty() against
one of these pages after invalidate_inode_pages() has decided that it
is clean.  This could happen if someone was performing O_DIRECT IO
against a file which was also mapped with MAP_SHARED.

So recheck the dirty state of the page inside the mapping->page_lock
and back out if the page has just been marked dirty.

This will also prevent the remove_from_page_cache() BUG which will occur
if someone marks the page dirty between the clear_page_dirty() and
remove_from_page_cache() calls in truncate_complete_page().

simple_prepare_write() currently memsets the entire page.  It only
needs to clear the parts which are outside the to-be-written region.
This change makes no difference to performance - that memset was just a
cache preload for the copy_from_user() in generic_file_write().  But
it's more correct.

Also, mark the page dirty in simple_commit_write(), not in
simple_prepare_write().  Because the page's contents are changed after
prepare_write().  This doesn't matter in practice, but it is setting a
bad example.

Also, add a flush_dcache_page() to simple_prepare_write().  Again, not
really needed because the page cannot be mapped into pagetables if it
is not uptodate.  But it is example code and should not be missing such
things.

From Bill Irwin.

Abstract out ramfs readpage(), prepare_write(), and commit_write()
operations.

Ram-backed filesystems are going to be doing a lot of zero-filled read
and write operations.  So in this patch, ramfs' implementations are
moved to libfs in anticipation of other callers.

Patch from Hugh Dickins <hugh@veritas.com>

Fix premature -EIO from blkdev_get_block: bdget initialize
bd_block_size consistent with bd_inode->i_blkbits (assigned by
new_inode).  Otherwise, subsequent set_blocksize can find bd_block_size
doesn't need updating, and skip updating i_blkbits, leaving them
inconsistent.

Local variable `data' is only used for debugging.

Now that the devicemapper hit the tree there's no more reason
to keep the uncompiling LVM1 code around and it's various hacks
to other files around, this patch removes it.

	* first application of the fact that block device methods are
per-disk and not per-major - IDE subdrivers got block_device_operations
of their own, redirects in ide.c are gone, so is a bunch of methods of
IDE subdrivers.

	* ide_..._ioctl() never use two of five arguments - inode and file.
Arguments removed.

	This chunk and the next one basically do equivalent of sard in the
right way - counters are exported per-disk in driverfs, as attributes of
disk or partition nodes.

	* do_open() cleaned up
	* we always pick block_device_operations from gendisk->fops now
	* register_blkdev() just stores the name of driver, nothing more
	* ->bd_op and ->bd_queue removed - we have that in gendisk
	* get_blkfops() is gone

	* we move allocation of gendisks in ide-probe to the moment when
queues are set up, so everything that wants to feed requests in one of
IDE queues can safely set ->rq_disk

	* per-major array eliminated, every disk is a separate source of
randomness

	* remove blk_dev[]
	* removed BLK_DEFAULT_QUEUE
	* moved definition of CURRENT into drivers that used it
	* removed definition of QUEUE from headers

	* compile fixes
	* switched to private queue
	* set ->queue

	* killed uses of CURRENT and QUEUE

	* switched to private queues
	* set ->queue

	* killed remaining CURRENT

	* switched to private queues
	* set ->queue and ->private_data
	* switched to use of ->bd_disk and ->rq_disk
	* cleaned up

	* switched to private queues
	* set ->queue and ->private_data
	* switched to use of ->bd_disk and ->rq_disk
	* folded recalibrate[] and special_op[] into hd_info[]
	* switched to passing pointers instead of indices
	* cleaned up

	* switched to private queues
	* set ->queue

	* switched to private queues
	* set ->queue and ->private_data
	* switched to use of ->bd_disk and ->rq_disk
	* fixed the problem with request_module() from open()
	* cleaned up

	* switched to private queues
	* set ->queue and ->private_data
	* switched to use of ->bd_disk and ->rq_disk
	* somewhat cleaned up

	* switched to private queues
	* set ->queue and ->private_data
	* switched to use of ->bd_disk

	* switched to private queues
	* set ->queue
	* cleaned up

	* switched to private queues
	* set ->queue
	* cleaned up

into mulgrave.(none):/home/jejb/BK/scsi-for-linus-2.5

by Doug Ledford, hch and alan.

From Dipankar

I missed sparc64 when I broke up read_barrier_depends in -mm and sent
to Linus.  Please apply this to your tree until Linus is back and I can
fix it.

Patch from Dipankar Sarma <dipankar@in.ibm.com>

There is a check in RCU for idle CPUs which signifies quiescent state
(and hence no reference to RCU protected data) which was broken when
interrupt counters were changed to use thread_info->preempt_count.

Martin's 32 CPU machine with many idle CPUs was not completing any RCU
grace period because RCU was forever waiting for idle CPUs to context
switch.  Had the idle check worked, this would not have happened.  With
no RCU happening, the dentries were getting "freed" (dentry stats
showing that) but not getting returned to slab.  This would not show up
in systems that are generally busy as context switches then would
happen in all CPUs and the per-CPU quiescent state counter would get
incremented during context switch.

This patch fixes a filesystem corrupting bug, present in 2.5.41 through
2.5.44.  It can cause ext2 indirect blocks to not be written out.  A
fsck will fix it up.

Under heavy memory pressure a PF_MEMALLOC task attemtps to write out a
blockdev page whose buffers are already under writeback and which were
dirtied while under writeback.

The writepage call returns -EAGAIN but because the caller is
PF_MEMALLOC, the page was not being marked dirty again.

The page sits on mapping->clean_pages for ever and it not written out.

The fix is to mark that page dirty again for all callers, regardless of
PF_MEMALLOC state.

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