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>

Switch timerfd to using fops->read_iter(), so it can support not just
O_NONBLOCK but IOCB_NOWAIT as well. With the latter, users like io_uring
interact with timerfds a lot better, as they can be driven purely
by the poll trigger.

Manually get and install the required fd, so that FMODE_NOWAIT can be
set before the file is installed into the file table.

No functional changes intended in this patch, it's purely a straight
conversion to using the read iterator method.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Resuming timekeeping is a clock-was-set event and uses the clock-was-set
notification mechanism. This is in the way of making the clock-was-set
update for hrtimers selective so unnecessary IPIs are avoided when a CPU
base does not have timers queued which are affected by the clock setting.

Provide a seperate timerfd_resume() interface so the resume logic and the
clock-was-set mechanism can be distangled in the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.395287410@linutronix.de

timerfd_settime() accepts an absolute value of the expiration time if
TFD_TIMER_ABSTIME is specified. This value is in the task's time namespace
and has to be converted to the host's time namespace.

Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-14-dima@arista.com

timerfd_show() uses a 'struct itimerspec' internally, but that is
deprecated because of the time_t overflow and a conflict with the glibc
type of the same name that is now incompatible in user space.

Use a pair of timespec64 variables instead as a simple replacement.

As this removes the last use of itimerspec from the kernel, allowing the
removal of the definition from the uapi headers along with timespec and
timeval later.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Use the hrtimer_cancel_wait_running() synchronization mechanism to prevent
priority inversion and live locks on PREEMPT_RT.

[ tglx: Split out of combo patch ]

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190730223828.600085866@linutronix.de

A lot of system calls that pass a time_t somewhere have an implementation
using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
been reworked so that this implementation can now be used on 32-bit
architectures as well.

The missing step is to redefine them using the regular SYSCALL_DEFINEx()
to get them out of the compat namespace and make it possible to build them
on 32-bit architectures.

Any system call that ends in 'time' gets a '32' suffix on its name for
that version, while the others get a '_time32' suffix, to distinguish
them from the normal version, which takes a 64-bit time argument in the
future.

In this step, only 64-bit architectures are changed, doing this rename
first lets us avoid touching the 32-bit architectures twice.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Christoph Hellwig suggested a slightly different path for handling
backwards compatibility with the 32-bit time_t based system calls:

Rather than simply reusing the compat_sys_* entry points on 32-bit
architectures unchanged, we get rid of those entry points and the
compat_time types by renaming them to something that makes more sense
on 32-bit architectures (which don't have a compat mode otherwise),
and then share the entry points under the new name with the 64-bit
architectures that use them for implementing the compatibility.

The following types and interfaces are renamed here, and moved
from linux/compat_time.h to linux/time32.h:

old				new
---				---
compat_time_t			old_time32_t
struct compat_timeval		struct old_timeval32
struct compat_timespec		struct old_timespec32
struct compat_itimerspec	struct old_itimerspec32
ns_to_compat_timeval()		ns_to_old_timeval32()
get_compat_itimerspec64()	get_old_itimerspec32()
put_compat_itimerspec64()	put_old_itimerspec32()
compat_get_timespec64()		get_old_timespec32()
compat_put_timespec64()		put_old_timespec32()

As we already have aliases in place, this patch addresses only the
instances that are relevant to the system call interface in particular,
not those that occur in device drivers and other modules. Those
will get handled separately, while providing the 64-bit version
of the respective interfaces.

I'm not renaming the timex, rusage and itimerval structures, as we are
still debating what the new interface will look like, and whether we
will need a replacement at all.

This also doesn't change the names of the syscall entry points, which can
be done more easily when we actually switch over the 32-bit architectures
to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Pull vfs aio updates from Al Viro:
 "Christoph's aio poll, saner this time around.

  This time it's pretty much local to fs/aio.c. Hopefully race-free..."

* 'work.aio' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  aio: allow direct aio poll comletions for keyed wakeups
  aio: implement IOCB_CMD_POLL
  aio: add a iocb refcount
  timerfd: add support for keyed wakeups

This prepares timerfd for use with aio poll.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Avi Kivity <avi@scylladb.com>