Delete create_proc_read_entry() as it no longer has any users.

Also delete read_proc_t, write_proc_t, the read_proc member of the
proc_dir_entry struct and the support functions that use them.  This saves a
pointer for every PDE allocated.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... it's done already by __fput()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it has grown by accident - directories there do *not* use page cache, so
there's nothing to write.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

we need to close the underlying procfs file and free ->private_data
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

switch binfmts that use ->read() to that (and to kernel_read()
in several cases in binfmt_flat - sure, it's nommu, but still,
doing ->read() into kmalloc'ed buffer...)
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

* serialize the call of ->release() on per-pdeo mutex
* don't remove pdeo from per-pde list until we are through with it
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

* leave ->proc_fops alone; make ->pde_users negative instead
* trim pde_opener
* move relevant code in fs/proc/inode.c
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Switch huge if-statement in __proc_file_read() around.  This then puts the
single line loop break immediately after the if-statement and allows us to
de-indent the huge comment and make it take fewer lines.  The code following
the if-statement then follows naturally from the call to dp->read_proc().
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Kill create_proc_entry() in favour of create_proc_read_entry(), proc_create()
and proc_create_data().
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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

The only part of proc_dir_entry the code outside of fs/proc
really cares about is PDE(inode)->data.  Provide a helper
for that; static inline for now, eventually will be moved
to fs/proc, along with the knowledge of struct proc_dir_entry
layout.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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>