This fixed a case that 'sparse' spotted where hpfs_setattr has an error return
that didn't go through it's path that unlocks.

This is against git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
version 6313e3c21743cc88bb5bd8aa72948ee1e83937b6.

Build tested only, I don't have an hpfs file system to test.

Dave

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.

Patched with:

git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

RCU free the struct inode. This will allow:

- Subsequent store-free path walking patch. The inode must be consulted for
  permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
  to take i_lock no longer need to take sb_inode_list_lock to walk the list in
  the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
  page lock to follow page->mapping.

The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.

In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.

The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

Change d_hash so it may be called from lock-free RCU lookups. See similar
patch for d_compare for details.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

Change d_compare so it may be called from lock-free RCU lookups. This
does put significant restrictions on what may be done from the callback,
however there don't seem to have been any problems with in-tree fses.
If some strange use case pops up that _really_ cannot cope with the
rcu-walk rules, we can just add new rcu-unaware callbacks, which would
cause name lookup to drop out of rcu-walk mode.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  genirq: Fix up irq_node() for irq_data changes.
  genirq: Add single IRQ reservation helper
  genirq: Warn if enable_irq is called before irq is set up

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  semaphore: Remove mutex emulation
  staging: Final semaphore cleanup
  jbd2: Convert jbd2_slab_create_sem to mutex
  hpfs: Convert sbi->hpfs_creation_de to mutex

Fix up trivial change/delete conflicts with deleted 'dream' drivers
(drivers/staging/dream/camera/{mt9d112.c,mt9p012_fox.c,mt9t013.c,s5k3e2fx.c})

sbi->hpfs_creation_de is used as mutex so make it a mutex.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
LKML-Reference: <20100907125056.228874895@linutronix.de>

... and switch of the obvious get_sb_bdev() users to ->mount()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>