Replace the now deprecated kmap_atomic() with kmap_local_page().

Optimize for the non-highmem cases and avoid disabling preemption and
pagefaults, the caller's context is atomic anyway, but that is irrelevant
to kmap. The memcpy itself does not require any such semantics and the
mapping would hold valid across context switches anyway. Further, highmem
is planned to to be removed[1].

[1] https://lore.kernel.org/all/4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com/

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://patch.msgid.link/20251118210706.1816303-1-dave@stgolabs.net
Signed-off-by: Christian Brauner <brauner@kernel.org>

Pull vfs pipe updates from Christian Brauner:

 - Introduce struct file_operations pipeanon_fops

 - Don't update {a,c,m}time for anonymous pipes to avoid the performance
   costs associated with it

 - Change pipe_write() to never add a zero-sized buffer

 - Limit the slots in pipe_resize_ring()

 - Use pipe_buf() to retrieve the pipe buffer everywhere

 - Drop an always true check in anon_pipe_write()

 - Cache 2 pages instead of 1

 - Avoid spurious calls to prepare_to_wait_event() in ___wait_event()

* tag 'vfs-6.15-rc1.pipe' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs/splice: Use pipe_buf() helper to retrieve pipe buffer
  fs/pipe: Use pipe_buf() helper to retrieve pipe buffer
  kernel/watch_queue: Use pipe_buf() to retrieve the pipe buffer
  fs/pipe: Limit the slots in pipe_resize_ring()
  wait: avoid spurious calls to prepare_to_wait_event() in ___wait_event()
  pipe: cache 2 pages instead of 1
  pipe: drop an always true check in anon_pipe_write()
  pipe: change pipe_write() to never add a zero-sized buffer
  pipe: don't update {a,c,m}time for anonymous pipes
  pipe: introduce struct file_operations pipeanon_fops

Use pipe_buf() helper to retrieve the pipe buffer in
post_one_notification() replacing the open-coded the logic.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250307052919.34542-3-kprateek.nayak@amd.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Currently, watch_queue_set_size() modifies the pipe buffers charged to
user->pipe_bufs without updating the pipe->nr_accounted on the pipe
itself, due to the if (!pipe_has_watch_queue()) test in
pipe_resize_ring(). This means that when the pipe is ultimately freed,
we decrement user->pipe_bufs by something other than what than we had
charged to it, potentially leading to an underflow. This in turn can
cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM.

To remedy this, explicitly account for the pipe usage in
watch_queue_set_size() to match the number set via account_pipe_buffers()

(It's unclear why watch_queue_set_size() does not update nr_accounted;
it may be due to intentional overprovisioning in watch_queue_set_size()?)

Fixes: e95aada4cb93d ("pipe: wakeup wr_wait after setting max_usage")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Link: https://lore.kernel.org/r/206682a8-0604-49e5-8224-fdbe0c12b460@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

We are attempting to eliminate page->index, so use page->private
instead.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20241125175443.2911738-1-willy@infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

fdget() is the first thing done in scope, all matching fdput() are
immediately followed by leaving the scope.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

	For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

When compiling with gcc version 14.0.0 20231220 (experimental)
and W=1, I've noticed the following warning:

kernel/watch_queue.c: In function 'watch_queue_set_size':
kernel/watch_queue.c:273:32: warning: 'kcalloc' sizes specified with 'sizeof'
in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
  273 |         pages = kcalloc(sizeof(struct page *), nr_pages, GFP_KERNEL);
      |                                ^~~~~~

Since 'n' and 'size' arguments of 'kcalloc()' are multiplied to
calculate the final size, their actual order doesn't affect the
result and so this is not a bug. But it's still worth to fix it.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Link: https://lore.kernel.org/r/20231221090139.12579-1-dmantipov@yandex.ru
Signed-off-by: Christian Brauner <brauner@kernel.org>

Currently, there is no overflow-check with memdup_user().

Use the new function memdup_array_user() instead of memdup_user() for
duplicating the user-space array safely.

Suggested-by: David Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-5-pstanner@redhat.com

NULL the dangling pipe reference while clearing watch_queue.

If not done, a reference to a freed pipe remains in the watch_queue,
as this function is called before freeing a pipe in free_pipe_info()
(see line 834 of fs/pipe.c).

The sole use of wqueue->defunct is for checking if the watch queue has
been cleared, but wqueue->pipe is also NULLed while clearing.

Thus, wqueue->defunct is superfluous, as wqueue->pipe can be checked
for NULL. Hence, the former can be removed.

Tested with keyutils testsuite.

Cc: stable@vger.kernel.org # 6.1
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Acked-by: David Howells <dhowells@redhat.com>
Message-Id: <20230605143616.640517-1-code@siddh.me>
Signed-off-by: Christian Brauner <brauner@kernel.org>