Make to_mnt_ns() static to address the following 'sparse' warning:

    fs/namespace.c:1731:22: warning: symbol 'to_mnt_ns' was not declared. Should it be static?

Link: http://lkml.kernel.org/r/20191209234830.156260-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In prepare_namespace(), do_mount() can be used instead of ksys_mount()
as the first and third argument are const strings in the kernel, the
second and fourth argument are passed through anyway, and the fifth
argument is NULL.

In do_mount_root(), ksys_mount() is called with the first and third
argument being already kernelspace strings, which do not need to be
copied over from userspace to kernelspace (again). The second and
fourth arguments are passed through to do_mount() anyway. The fifth
argument, while already residing in kernelspace, needs to be put into
a page of its own. Then, do_mount() can be used instead of
ksys_mount().

Once this is done, there are no in-kernel users to ksys_mount() left,
which can therefore be removed.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

Pull misc vfs cleanups from Al Viro:
 "No common topic, just three cleanups".

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make __d_alloc() static
  fs/namespace: add __user to open_tree and move_mount syscalls
  fs/fnctl: fix missing __user in fcntl_rw_hint()

Thw open_tree and move_mount syscalls take names from the
user, so add the __user to these to ensure the following
warnings from sparse are fixed:

fs/namespace.c:2392:35: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:2392:35:    expected char const [noderef] <asn:1> *name
fs/namespace.c:2392:35:    got char const *filename
fs/namespace.c:3541:38: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:3541:38:    expected char const [noderef] <asn:1> *name
fs/namespace.c:3541:38:    got char const *from_pathname
fs/namespace.c:3550:36: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:3550:36:    expected char const [noderef] <asn:1> *name
fs/namespace.c:3550:36:    got char const *to_pathname

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

After do_add_mount() returns success, the caller doesn't hold a
reference to the 'struct mount' anymore.  So it's invalid to access it
in mnt_warn_timestamp_expiry().

Fix it by calling mnt_warn_timestamp_expiry() before do_add_mount()
rather than after, and adjusting the warning message accordingly.

Reported-by: syzbot+da4f525235510683d855@syzkaller.appspotmail.com
Fixes: f8b92ba67c5d ("mount: Add mount warning for impending timestamp expiry")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Merge more updates from Andrew Morton:

 - almost all of the rest of -mm

 - various other subsystems

Subsystems affected by this patch series:
  memcg, misc, core-kernel, lib, checkpatch, reiserfs, fat, fork,
  cpumask, kexec, uaccess, kconfig, kgdb, bug, ipc, lzo, kasan, madvise,
  cleanups, pagemap

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (77 commits)
  arch/sparc/include/asm/pgtable_64.h: fix build
  mm: treewide: clarify pgtable_page_{ctor,dtor}() naming
  ntfs: remove (un)?likely() from IS_ERR() conditions
  IB/hfi1: remove unlikely() from IS_ERR*() condition
  xfs: remove unlikely() from WARN_ON() condition
  wimax/i2400m: remove unlikely() from WARN*() condition
  fs: remove unlikely() from WARN_ON() condition
  xen/events: remove unlikely() from WARN() condition
  checkpatch: check for nested (un)?likely() calls
  hexagon: drop empty and unused free_initrd_mem
  mm: factor out common parts between MADV_COLD and MADV_PAGEOUT
  mm: introduce MADV_PAGEOUT
  mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM
  mm: introduce MADV_COLD
  mm: untag user pointers in mmap/munmap/mremap/brk
  vfio/type1: untag user pointers in vaddr_get_pfn
  tee/shm: untag user pointers in tee_shm_register
  media/v4l2-core: untag user pointers in videobuf_dma_contig_user_get
  drm/radeon: untag user pointers in radeon_gem_userptr_ioctl
  drm/amdgpu: untag user pointers
  ...

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

In copy_mount_options a user address is being subtracted from TASK_SIZE.
If the address is lower than TASK_SIZE, the size is calculated to not
allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
However if the address is tagged, then the size will be calculated
incorrectly.

Untag the address before subtracting.

Link: http://lkml.kernel.org/r/1de225e4a54204bfd7f25dac2635e31aa4aa1d90.1563904656.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull fuse updates from Miklos Szeredi:

 - Continue separating the transport (user/kernel communication) and the
   filesystem layers of fuse. Getting rid of most layering violations
   will allow for easier cleanup and optimization later on.

 - Prepare for the addition of the virtio-fs filesystem. The actual
   filesystem will be introduced by a separate pull request.

 - Convert to new mount API.

 - Various fixes, optimizations and cleanups.

* tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (55 commits)
  fuse: Make fuse_args_to_req static
  fuse: fix memleak in cuse_channel_open
  fuse: fix beyond-end-of-page access in fuse_parse_cache()
  fuse: unexport fuse_put_request
  fuse: kmemcg account fs data
  fuse: on 64-bit store time in d_fsdata directly
  fuse: fix missing unlock_page in fuse_writepage()
  fuse: reserve byteswapped init opcodes
  fuse: allow skipping control interface and forced unmount
  fuse: dissociate DESTROY from fuseblk
  fuse: delete dentry if timeout is zero
  fuse: separate fuse device allocation and installation in fuse_conn
  fuse: add fuse_iqueue_ops callbacks
  fuse: extract fuse_fill_super_common()
  fuse: export fuse_dequeue_forget() function
  fuse: export fuse_get_unique()
  fuse: export fuse_send_init_request()
  fuse: export fuse_len_args()
  fuse: export fuse_end_request()
  fuse: fix request limit
  ...

Pull y2038 vfs updates from Arnd Bergmann:
 "Add inode timestamp clamping.

  This series from Deepa Dinamani adds a per-superblock minimum/maximum
  timestamp limit for a file system, and clamps timestamps as they are
  written, to avoid random behavior from integer overflow as well as
  having different time stamps on disk vs in memory.

  At mount time, a warning is now printed for any file system that can
  represent current timestamps but not future timestamps more than 30
  years into the future, similar to the arbitrary 30 year limit that was
  added to settimeofday().

  This was picked as a compromise to warn users to migrate to other file
  systems (e.g. ext4 instead of ext3) when they need the file system to
  survive beyond 2038 (or similar limits in other file systems), but not
  get in the way of normal usage"

* tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground:
  ext4: Reduce ext4 timestamp warnings
  isofs: Initialize filesystem timestamp ranges
  pstore: fs superblock limits
  fs: omfs: Initialize filesystem timestamp ranges
  fs: hpfs: Initialize filesystem timestamp ranges
  fs: ceph: Initialize filesystem timestamp ranges
  fs: sysv: Initialize filesystem timestamp ranges
  fs: affs: Initialize filesystem timestamp ranges
  fs: fat: Initialize filesystem timestamp ranges
  fs: cifs: Initialize filesystem timestamp ranges
  fs: nfs: Initialize filesystem timestamp ranges
  ext4: Initialize timestamps limits
  9p: Fill min and max timestamps in sb
  fs: Fill in max and min timestamps in superblock
  utimes: Clamp the timestamps before update
  mount: Add mount warning for impending timestamp expiry
  timestamp_truncate: Replace users of timespec64_trunc
  vfs: Add timestamp_truncate() api
  vfs: Add file timestamp range support

Pull file locking updates from Jeff Layton:
 "Just a couple of minor bugfixes, a revision to a tracepoint to account
  for some earlier changes to the internals, and a patch to add a
  pr_warn message when someone tries to mount a filesystem with '-o
  mand' on a kernel that has that support disabled"

* tag 'filelock-v5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: fix a memory leak bug in __break_lease()
  locks: print a warning when mount fails due to lack of "mand" support
  locks: Fix procfs output for file leases
  locks: revise generic_add_lease tracepoint