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

Same as single_open(), but preallocates the buffer of given size.
Doesn't make any sense for sizes up to PAGE_SIZE and doesn't make
sense if output of show() exceeds PAGE_SIZE only rarely - seq_read()
will take care of growing the buffer and redoing show().  If you
_know_ that it will be large, it might make more sense to look into
saner iterator, rather than go with single-shot one.  If that's
impossible, single_open_size() might be for you.

Again, don't use that without a good reason; occasionally that's really
the best way to go, but very often there are better solutions.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

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

Just have it pinned in dcache all along and let procfs ->kill_sb()
drop it before kill_anon_super().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

and rename __free_pipe_info() to free_pipe_info()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

not used anymore
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it's used only as a flag to distinguish normal pipes/FIFOs from the
internal per-task one used by file-to-file splice.  And pipe->files
would work just as well for that purpose...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/pipe.c file_operations methods *know* that pipe is not an internal one;
no need to check pipe->inode for those callers.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

simplify get_pipe_info(), while we are at it
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

now it can be done - put mutex into pipe_inode_info, use it instead
of ->i_mutex
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

* new field - pipe->files; number of struct file over that pipe (all
  sharing the same inode, of course); protected by inode->i_lock.
* pipe_release() decrements pipe->files, clears inode->i_pipe when
  if the counter has reached 0 (all under ->i_lock) and, in that case,
  frees pipe after having done pipe_unlock()
* fifo_open() starts with grabbing ->i_lock, and either bumps pipe->files
  if ->i_pipe was non-NULL or allocates a new pipe (dropping and regaining
  ->i_lock) and rechecks ->i_pipe; if it's still NULL, inserts new pipe
  there, otherwise bumps ->i_pipe->files and frees the one we'd allocated.
  At that point we know that ->i_pipe is non-NULL and won't go away, so
  we can do pipe_lock() on it and proceed as we used to.  If we end up
  failing, decrement pipe->files and if it reaches 0 clear ->i_pipe and
  free the sucker after pipe_unlock().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

* use the fact that file_inode(file)->i_pipe doesn't change
  while the file is opened - no locks needed to access that.
* switch to pipe_lock/pipe_unlock where it's easy to do
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

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

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

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

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

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

... and take to fs/read_write.c
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

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

... so that writev(2) doesn't miss it.  Get rid of hpfs_file_write().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

look for file_capable() in there...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and provide namespace_lock() as a trivial wrapper;
switch to those two consistently.

Result is patterned after rtnl_lock/rtnl_unlock pair.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

which allows to kill the last argument of umount_tree() and make release_mounts()
static.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

... it's always &unmounted.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

global list of release_mounts() fodder, protected by namespace_sem;
eventually, all umount_tree() callers will use it as kill list.
Helper picking the contents of that list, releasing namespace_sem
and doing release_mounts() on what it got.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

do_loopback calls lock_mount(path) and forget to unlock_mount
if clone_mnt or copy_mnt fails.

[   77.661566] ================================================
[   77.662939] [ BUG: lock held when returning to user space! ]
[   77.664104] 3.9.0-rc5+ #17 Not tainted
[   77.664982] ------------------------------------------------
[   77.666488] mount/514 is leaving the kernel with locks still held!
[   77.668027] 2 locks held by mount/514:
[   77.668817]  #0:  (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffff811cca22>] lock_mount+0x32/0xe0
[   77.671755]  #1:  (&namespace_sem){+++++.}, at: [<ffffffff811cca3a>] lock_mount+0x4a/0xe0
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

just what it sounds like; do that only to procfs subtrees you've
created - doing that to something shared with another driver is
not only antisocial, but might cause interesting races with
proc_create() and its ilk.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

... lest we get livelocks between path_is_under() and d_path() and friends.

The thing is, wrt fairness lglocks are more similar to rwsems than to rwlocks;
it is possible to have thread B spin on attempt to take lock shared while thread
A is already holding it shared, if B is on lower-numbered CPU than A and there's
a thread C spinning on attempt to take the same lock exclusive.

As the result, we need consistent ordering between vfsmount_lock (lglock) and
rename_lock (seq_lock), even though everything that takes both is going to take
vfsmount_lock only shared.
Spotted-by: NBrad Spengler <spender@grsecurity.net>
Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

vfs_writev() updates the offset argument - but the code then passes the
offset to vfs_fsync_range(). Since offset now points to the offset after
what was just written, this is probably not what was intended

Introduced by face1502 "nfsd: use
vfs_fsync_range(), not O_SYNC, for stable writes".
Signed-off-by: NKent Overstreet <koverstreet@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: stable@vger.kernel.org
Reviewed-by: NZach Brown <zab@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Dave Jones found another /proc issue with his Trinity tool: thanks to
the namespace model, we can have multiple /proc dentries that point to
the same inode, aliasing directories in /proc/<pid>/net/ for example.

This ends up being a total disaster, because it acts like hardlinked
directories, and causes locking problems.  We rely on the topological
sort of the inodes pointed to by dentries, and if we have aliased
directories, that odering becomes unreliable.

In short: don't do this.  Multiple dentries with the same (directory)
inode is just a bad idea, and the namespace code should never have
exposed things this way.  But we're kind of stuck with it.

This solves things by just always allocating a new inode during /proc
dentry lookup, instead of using "iget_locked()" to look up existing
inodes by superblock and number.  That actually simplies the code a bit,
at the cost of potentially doing more inode [de]allocations.

That said, the inode lookup wasn't free either (and did a lot of locking
of inodes), so it is probably not that noticeable.  We could easily keep
the old lookup model for non-directory entries, but rather than try to
be excessively clever this just implements the minimal and simplest
workaround for the problem.
Reported-and-tested-by: NDave Jones <davej@redhat.com>
Analyzed-by: NAl Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We've had several reports of people attempting to mount Windows 8 shares
and getting failures with a return code of -EINVAL. The default sec=
mode changed recently to sec=ntlmssp. With that, we expect and parse a
SPNEGO blob from the server in the NEGOTIATE reply.

The current decode_negTokenInit function first parses all of the
mechTypes and then tries to parse the rest of the negTokenInit reply.
The parser however currently expects a mechListMIC or nothing to follow the
mechTypes, but Windows 8 puts a mechToken field there instead to carry
some info for the new NegoEx stuff.

In practice, we don't do anything with the fields after the mechTypes
anyway so I don't see any real benefit in continuing to parse them.
This patch just has the kernel ignore the fields after the mechTypes.
We'll probably need to reinstate some of this if we ever want to support
NegoEx.
Reported-by: NJason Burgess <jason@jacknife2.dns2go.com>
Reported-by: NYan Li <elliot.li.tech@gmail.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

default_file_splice_from() ends up calling vfs_write() (via very convoluted
callchain).  It's an overkill, since we already have done rw_verify_area()
in the caller by the time we call vfs_write() we are under set_fs(KERNEL_DS),
so access_ok() is also pointless.  Add a new helper (__kernel_write()),
use it instead of kernel_write() in there.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

In order to be able to safely return the layout in nfs4_proc_setattr,
we need to block new uses of the layout, wait for all outstanding
users of the layout to complete, commit the layout and then return it.

This patch adds a helper in order to do all this safely.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: Boaz Harrosh <bharrosh@panasas.com>