In case of error, the function p9_client_walk returns an ERR pointer, but
never returns a NULL pointer.  So a NULL test that comes after an IS_ERR
test should be deleted.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@match_bad_null_test@
expression x, E;
statement S1,S2;
@@
x = p9_client_walk(...)
... when != x = E
*  if (x != NULL)
S1 else S2
// </smpl>

Signed-off-by: Julien Brunel <brunel@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

The legacy protocol's open operation doesn't handle an append operation
(it is expected that the client take care of it).  We were incorrectly
passing the extended protocol's flag through even in legacy mode.  This
was reported in bugzilla report #10689.  This patch fixes the problem
by disallowing extended protocol open modes from being passed in legacy
mode and implemented append functionality on the client side by adding
a seek after the open.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

There was some cleanup issues during early mount which would trigger
a kernel bug for certain types of failure.  This patch reorganizes the
cleanup to get rid of the bad behavior.

This also merges the 9pnet and 9pnet_fd modules for the purpose of
configuration and initialization.  Keeping the fd transport separate
from the core 9pnet code seemed like a good idea at the time, but in
practice has caused more harm and confusion than good.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

Signed-off-by: Jim Meyering <meyering@redhat.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Eric Van Hensbergen <ericvh@gmail.com>

The kernel-doc comments of much of the 9p system have been in disarray since
reorganization.  This patch fixes those problems, adds additional documentation
and a template book which collects the 9p information.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

match_strcpy() is a somewhat creepy function: the caller needs to make sure
that the destination buffer is big enough, and when he screws up or
forgets, match_strcpy() happily overruns the buffer.

There's exactly one customer: v9fs_parse_options().  I believe it currently
can't overflow its buffer, but that's not exactly obvious.

The source string is a substing of the mount options.  The kernel silently
truncates those to PAGE_SIZE bytes, including the terminating zero.  See
compat_sys_mount() and do_mount().

The destination buffer is obtained from __getname(), which allocates from
name_cachep, which is initialized by vfs_caches_init() for size PATH_MAX.

We're safe as long as PATH_MAX <= PAGE_SIZE.  PATH_MAX is 4096.  As far as
I know, the smallest PAGE_SIZE is also 4096.

Here's a patch that makes the code a bit more obviously correct.  It
doesn't depend on PATH_MAX <= PAGE_SIZE.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: Jim Meyering <meyering@redhat.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

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

None of these files use any of the functionality promised by
asm/semaphore.h.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

Convert instances of ERR_PTR(PTR_ERR(p)) to ERR_CAST(p) using:

perl -spi -e 's/ERR_PTR[(]PTR_ERR[(](.*)[)][)]/ERR_CAST(\1)/' `grep -rl 'ERR_PTR[(]*PTR_ERR' fs crypto net security`

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>