That thing has devolved into rats nest of gotos; sane use of unlikely()
gets rid of that horror and gives much more readable structure:
	* make a fast attempt to find a dentry; false negatives are OK.
In RCU mode if everything went fine, we are done, otherwise just drop
out of RCU.  If we'd done (RCU) ->d_revalidate() and it had not refused
outright (i.e. didn't give us -ECHILD), remember its result.
	* now we are not in RCU mode and hopefully have a dentry.  If we
do not, lock parent, do full d_lookup() and if that has not found anything,
allocate and call ->lookup().  If we'd done that ->lookup(), remember that
dentry is good and we don't need to revalidate it.
	* now we have a dentry.  If it has ->d_revalidate() and we can't
skip it, call it.
	* hopefully dentry is good; if not, either fail (in case of error)
or try to invalidate it.  If d_invalidate() has succeeded, drop it and
retry everything as if original attempt had not found a dentry.
	* now we can finish it up - deal with mountpoint crossing and
automount.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

There used to be time when ->d_revalidate() couldn't return an error.
So intents code had lookup_instantiate_filp() stash ERR_PTR(error)
in nd->intent.open.filp and had it checked after lookup_hash(), to
catch the otherwise silent failures.  That had been introduced by
commit 4af4c52f.  These days
->d_revalidate() can and does propagate errors back to callers
explicitly, so this check isn't needed anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and clean up a bit more
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

We have a bunch of diverging codepaths in do_last(); some of
them converge, but the case of having to create a new file
duplicates large part of common tail of the rest and exits
separately.  Massage them so that they could be merged.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

Lift it to lookup_one_len() and link_path_walk() resp. into the
same place where we calculated default hash function of the same
name.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

Instead of path_lookupat() doing trailing symlink resolution,
use the same scheme as on the O_CREAT side.  Walk with
LOOKUP_PARENT, then (in do_last()) look the final component
up, then either open it or return error or, if it's a symlink,
give the symlink back to path_openat() to be resolved there.

The really messy complication here is RCU.  We don't want to drop
out of RCU mode before the final lookup, since we don't want to
bounce parent directory ->d_count without a good reason.

Result is _not_ pretty; later in the series we'll clean it up.
For now we are roughly back where we'd been before the revert
done by Nick's series - top-level logics of path_openat() is
cleaned up, do_last() does actual opening, symlink resolution is
done uniformly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Don't stash the struct file * used as starting point of walk in nameidata;
pass file ** to path_init() instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

New helper: terminate_walk().  An error has happened during pathname
resolution and we either drop nd->path or terminate RCU, depending
the mode we had been in.  After that, nd is essentially empty.
Switch link_path_walk() to using that for cleanup.

Now the top-level logics in link_path_walk() is back to sanity.  RCU
dependencies are in the lower-level functions.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Now we have do_follow_link() guaranteed to leave without dangling RCU
and the next step will get LOOKUP_RCU logics completely out of
link_path_walk().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

getting LOOKUP_RCU checks out of link_path_walk()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

new helper: path_openat().  Does what do_filp_open() does, except
that it tries only the walk mode (RCU/normal/force revalidation)
it had been told to.

Both create and non-create branches are using path_lookupat() now.
Fixed the double audit_inode() in non-create branch.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

take calculation of open_flags by open(2) arguments into new helper
in fs/open.c, move filp_open() over there, have it and do_sys_open()
use that helper, switch exec.c callers of do_filp_open() to explicit
(and constant) struct open_flags.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

No point messing with passing shitloads of "operation mode" arguments
to do_open() one by one, especially since they are not going to change
during do_filp_open().  Collect them into a struct, fill it and pass
to do_last() by reference.

Make sure that lookup intent flags are correctly set and removed - we
want them for do_last(), but they make no sense for __do_follow_link().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

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

instead of ad-hackery around need_reval_dot(), do the following:
set a flag (LOOKUP_JUMPED) in the beginning of path, on absolute
symlink traversal, on ".." and on procfs-style symlinks.  Clear on
normal components, leave unchanged on ".".  Non-nested callers of
link_path_walk() call handle_reval_path(), which checks that flag
is set and that fs does want the final revalidate thing, then does
->d_revalidate().  In link_path_walk() all the return_reval stuff
is gone.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

no need to do it in three places...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Actual dependency on whether we want RCU or not is in 3 small areas
(as it ought to be) and everything around those is the same in both
versions.  Since each function has only one caller and those callers
are on two sides of if (flags & LOOKUP_RCU), it's easier and cleaner
to merge them and pull the checks inside.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

New helper: path_lookupat().  Basically, what do_path_lookup() boils to
modulo -ECHILD/-ESTALE handler.  path_walk* family is gone; vfs_path_lookup()
is using link_path_walk() directly, do_path_lookup() and do_filp_open()
are using path_lookupat().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

all remaining callers pass LOOKUP_PARENT to it, so
flags argument can die; renamed to kern_path_parent()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

don't rely on pathname resolution ending up twice at the same point...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Fix for a dumb preadv()/pwritev() compat bug - unlike the native
variants, compat_... ones forget to check FMODE_P{READ,WRITE}, so e.g.
on pipe the native preadv() will fail with -ESPIPE and compat one will
act as readv() and succeed.  Not critical, but it's a clear bug with trivial
fix.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

* 'media_fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6:
  [media] mantis_pci: remove asm/pgtable.h include
  [media] tda829x: fix regression in probe functions
  [media] mceusb: don't claim multifunction device non-IR parts
  [media] nuvoton-cir: fix wake from suspend
  [media] cx18: Add support for Hauppauge HVR-1600 models with s5h1411
  [media] ivtv: Fix corrective action taken upon DMA ERR interrupt to avoid hang
  [media] cx25840: fix probing of cx2583x chips
  [media] cx23885: Remove unused 'err:' labels to quiet compiler warning
  [media] cx23885: Revert "Check for slave nack on all transactions"
  [media] DiB7000M: add pid filtering
  [media] Fix sysfs rc protocol lookup for rc-5-sz
  [media] au0828: fix VBI handling when in V4L2 streaming mode
  [media] ir-raw: Properly initialize the IR event (BZ#27202)
  [media] s2255drv: firmware re-loading changes
  [media] Fix double free of video_device in mem2mem_testdev
  [media] DM04/QQBOX memcpy to const char fix

This patch fixes an issue in OpenIPMI module where sometimes an ABORT command
is sent after sending an IPMI request to BMC causing the IPMI request to fail.
Signed-off-by: YiCheng Doe <yicheng.doe@hp.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Tom Mingarelli <thomas.mingarelli@hp.com>
Tested-by: Andy Cress <andy.cress@us.kontron.com>
Tested-by: Mika Lansirine <Mika.Lansirinne@stonesoft.com>
Tested-by: Brian De Wolf <bldewolf@csupomona.edu>
Cc: Jean Michel Audet <Jean-Michel.Audet@ca.Kontron.com>
Cc: Jozef Sudelsky <jozef.sudolsky@elbiahosting.sk>
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  fs/dcache: allow d_obtain_alias() to return unhashed dentries
  Check for immutable/append flag in fallocate path
  sysctl: the include of rcupdate.h is only needed in the kernel
  fat: fix d_revalidate oopsen on NFS exports
  jfs: fix d_revalidate oopsen on NFS exports
  ocfs2: fix d_revalidate oopsen on NFS exports
  gfs2: fix d_revalidate oopsen on NFS exports
  fuse: fix d_revalidate oopsen on NFS exports
  ceph: fix d_revalidate oopsen on NFS exports
  reiserfs xattr ->d_revalidate() shouldn't care about RCU
  /proc/self is never going to be invalidated...

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, UV: Initialize the broadcast assist unit base destination node id properly
  x86, numa: Fix numa_emulation code with memory-less node0
  x86, build: Make sure mkpiggy fails on read error

Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Fix sched rt group scheduling when hierachy is enabled

* 'perf/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf symbols: Avoid resolving [kernel.kallsyms] to real path for buildid cache
  perf symbols: Fix vmlinux path when not using --symfs

This reverts commit 951f3512

    drm/i915: Do not handle backlight combination mode specially

since this commit introduced other regressions due to untouched LBPC
register, e.g. the backlight dimmed after resume.

In addition to the revert, this patch includes a fix for the original
issue (weird backlight levels) by removing the wrong bit shift for
computing the current backlight level.
Also, including typo fixes (lpbc -> lbpc).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34524Acked-by: Indan Zupancic <indan@nul.nu>
Reviewed-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Without this patch, inodes are not promptly freed on last close of an
unlinked file by an nfs client:

	client$ mount -tnfs4 server:/export/ /mnt/
	client$ tail -f /mnt/FOO
	...
	server$ df -i /export
	server$ rm /export/FOO
	(^C the tail -f)
	server$ df -i /export
	server$ echo 2 >/proc/sys/vm/drop_caches
	server$ df -i /export

the df's will show that the inode is not freed on the filesystem until
the last step, when it could have been freed after killing the client's
tail -f. On-disk data won't be deallocated either, leading to possible
spurious ENOSPC.

This occurs because when the client does the close, it arrives in a
compound with a putfh and a close, processed like:

	- putfh: look up the filehandle.  The only alias found for the
	  inode will be DCACHE_UNHASHED alias referenced by the filp
	  this, so it creates a new DCACHE_DISCONECTED dentry and
	  returns that instead.
	- close: closes the existing filp, which is destroyed
	  immediately by dput() since it's DCACHE_UNHASHED.
	- end of the compound: release the reference
	  to the current filehandle, and dput() the new
	  DCACHE_DISCONECTED dentry, which gets put on the
	  unused list instead of being destroyed immediately.

Nick Piggin suggested fixing this by allowing d_obtain_alias to return
the unhashed dentry that is referenced by the filp, instead of making it
create a new dentry.

Leave __d_find_alias() alone to avoid changing behavior of other
callers.

Also nfsd doesn't need all the checks of __d_find_alias(); any dentry,
hashed or unhashed, disconnected or not, should work.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In the fallocate path the kernel doesn't check for the immutable/append
flag. It's possible to have a race condition in this scenario: an
application open a file in read/write and it does something, meanwhile
root set the immutable flag on the file, the application at that point
can call fallocate with success. In addition, we don't allow to do any
unreserve operation on an append only file but only the reserve one.
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>