Replace 8 leading spaces with a tab to follow kernel coding style.

Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Link: https://lore.kernel.org/20250820133424.1667467-1-zhangguopeng@kylinos.cn
Signed-off-by: Christian Brauner <brauner@kernel.org>

Pull mount fixes from Al Viro:
 "Fixes for several recent mount-related regressions"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  change_mnt_propagation(): calculate propagation source only if we'll need it
  use uniform permission checks for all mount propagation changes
  propagate_umount(): only surviving overmounts should be reparented
  fix the softlockups in attach_recursive_mnt()

do_change_type() and do_set_group() are operating on different
aspects of the same thing - propagation graph.  The latter
asks for mounts involved to be mounted in namespace(s) the caller
has CAP_SYS_ADMIN for.  The former is a mess - originally it
didn't even check that mount *is* mounted.  That got fixed,
but the resulting check turns out to be too strict for userland -
in effect, we check that mount is in our namespace, having already
checked that we have CAP_SYS_ADMIN there.

What we really need (in both cases) is
	* only touch mounts that are mounted.  That's a must-have
constraint - data corruption happens if it get violated.
	* don't allow to mess with a namespace unless you already
have enough permissions to do so (i.e. CAP_SYS_ADMIN in its userns).

That's an equivalent of what do_set_group() does; let's extract that
into a helper (may_change_propagation()) and use it in both
do_set_group() and do_change_type().

Fixes: 12f147ddd6de "do_change_type(): refuse to operate on unmounted/not ours mounts"
Acked-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Tested-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In case when we mounting something on top of a large stack of overmounts,
all of them being peers of each other, we get quadratic time by the
depth of overmount stack.  Easily fixed by doing commit_tree() before
reparenting the overmount; simplifies commit_tree() as well - it doesn't
need to skip the already mounted stuff that had been reparented on top
of the new mounts.

Since we are holding mount_lock through both reparenting and call of
commit_tree(), the order does not matter from the mount hash point
of view.

Reported-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Tested-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: 663206854f02 "copy_tree(): don't link the mounts via mnt_list"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The lflags value used to look up from_path was overwritten by the one used
to look up to_path.

In other words, from_path was looked up with the wrong lflags value. Fix it.

Fixes: f9fde814de37 ("fs: support getname_maybe_null() in move_mount()")
Signed-off-by: Yuntao Wang <yuntao.wang@linux.dev>
Link: https://lore.kernel.org/20250811052426.129188-1-yuntao.wang@linux.dev
[Christian Brauner <brauner@kernel.org>: massage patch]
Signed-off-by: Christian Brauner <brauner@kernel.org>

As described in commit 7a54947e727b ('Merge patch series "fs: allow
changing idmappings"'), open_tree_attr(2) was necessary in order to
allow for a detached mount to be created and have its idmappings changed
without the risk of any racing threads operating on it. For this reason,
mount_setattr(2) still does not allow for id-mappings to be changed.

However, there was a bug in commit 2462651ffa76 ("fs: allow changing
idmappings") which allowed users to bypass this restriction by calling
open_tree_attr(2) *without* OPEN_TREE_CLONE.

can_idmap_mount() prevented this bug from allowing an attached
mountpoint's id-mapping from being modified (thanks to an is_anon_ns()
check), but this still allows for detached (but visible) mounts to have
their be id-mapping changed. This risks the same UAF and locking issues
as described in the merge commit, and was likely unintentional.

Fixes: 2462651ffa76 ("fs: allow changing idmappings")
Cc: stable@vger.kernel.org # v6.15+
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/20250808-open_tree_attr-bugfix-idmap-v1-1-0ec7bc05646c@cyphar.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Pull namespace updates from Christian Brauner:
 "This contains namespace updates. This time specifically for nsfs:

   - Userspace heavily relies on the root inode numbers for namespaces
     to identify the initial namespaces. That's already a hard
     dependency. So we cannot change that anymore. Move the initial
     inode numbers to a public header and align the only two namespaces
     that currently don't do that with all the other namespaces.

   - The root inode of /proc having a fixed inode number has been part
     of the core kernel ABI since its inception, and recently some
     userspace programs (mainly container runtimes) have started to
     explicitly depend on this behaviour.

     The main reason this is useful to userspace is that by checking
     that a suspect /proc handle has fstype PROC_SUPER_MAGIC and is
     PROCFS_ROOT_INO, they can then use openat2() together with
     RESOLVE_{NO_{XDEV,MAGICLINK},BENEATH} to ensure that there isn't a
     bind-mount that replaces some procfs file with a different one.

     This kind of attack has lead to security issues in container
     runtimes in the past (such as CVE-2019-19921) and libraries like
     libpathrs[1] use this feature of procfs to provide safe procfs
     handling functions"

* tag 'vfs-6.17-rc1.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  uapi: export PROCFS_ROOT_INO
  mntns: use stable inode number for initial mount ns
  netns: use stable inode number for initial mount ns
  nsfs: move root inode number to uapi

Pull misc VFS updates from Christian Brauner:
 "This contains the usual selections of misc updates for this cycle.

  Features:

   - Add ext4 IOCB_DONTCACHE support

     This refactors the address_space_operations write_begin() and
     write_end() callbacks to take const struct kiocb * as their first
     argument, allowing IOCB flags such as IOCB_DONTCACHE to propagate
     to the filesystem's buffered I/O path.

     Ext4 is updated to implement handling of the IOCB_DONTCACHE flag
     and advertises support via the FOP_DONTCACHE file operation flag.

     Additionally, the i915 driver's shmem write paths are updated to
     bypass the legacy write_begin/write_end interface in favor of
     directly calling write_iter() with a constructed synchronous kiocb.
     Another i915 change replaces a manual write loop with
     kernel_write() during GEM shmem object creation.

  Cleanups:

   - don't duplicate vfs_open() in kernel_file_open()

   - proc_fd_getattr(): don't bother with S_ISDIR() check

   - fs/ecryptfs: replace snprintf with sysfs_emit in show function

   - vfs: Remove unnecessary list_for_each_entry_safe() from
     evict_inodes()

   - filelock: add new locks_wake_up_waiter() helper

   - fs: Remove three arguments from block_write_end()

   - VFS: change old_dir and new_dir in struct renamedata to dentrys

   - netfs: Remove unused declaration netfs_queue_write_request()

  Fixes:

   - eventpoll: Fix semi-unbounded recursion

   - eventpoll: fix sphinx documentation build warning

   - fs/read_write: Fix spelling typo

   - fs: annotate data race between poll_schedule_timeout() and
     pollwake()

   - fs/pipe: set FMODE_NOWAIT in create_pipe_files()

   - docs/vfs: update references to i_mutex to i_rwsem

   - fs/buffer: remove comment about hard sectorsize

   - fs/buffer: remove the min and max limit checks in __getblk_slow()

   - fs/libfs: don't assume blocksize <= PAGE_SIZE in
     generic_check_addressable

   - fs_context: fix parameter name in infofc() macro

   - fs: Prevent file descriptor table allocations exceeding INT_MAX"

* tag 'vfs-6.17-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
  netfs: Remove unused declaration netfs_queue_write_request()
  eventpoll: fix sphinx documentation build warning
  ext4: support uncached buffered I/O
  mm/pagemap: add write_begin_get_folio() helper function
  fs: change write_begin/write_end interface to take struct kiocb *
  drm/i915: Refactor shmem_pwrite() to use kiocb and write_iter
  drm/i915: Use kernel_write() in shmem object create
  eventpoll: Fix semi-unbounded recursion
  vfs: Remove unnecessary list_for_each_entry_safe() from evict_inodes()
  fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable
  fs/buffer: remove the min and max limit checks in __getblk_slow()
  fs: Prevent file descriptor table allocations exceeding INT_MAX
  fs: Remove three arguments from block_write_end()
  fs/ecryptfs: replace snprintf with sysfs_emit in show function
  fs: annotate suspected data race between poll_schedule_timeout() and pollwake()
  docs/vfs: update references to i_mutex to i_rwsem
  fs/buffer: remove comment about hard sectorsize
  fs_context: fix parameter name in infofc() macro
  VFS: change old_dir and new_dir in struct renamedata to dentrys
  proc_fd_getattr(): don't bother with S_ISDIR() check
  ...

We are holding namespace_sem shared and we have not done any group
id allocations since we grabbed it.  Therefore IS_MNT_SHARED(m)
is equivalent to non-zero m->mnt_group_id.

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

All places where we call set_mnt_shared() are guaranteed to have
non-zero ->mnt_group_id - either by explicit test, or by having
done successful invent_group_ids() covering the same mount since
we'd grabbed namespace_sem.

The opposite combination (non-zero ->mnt_group_id and !IS_MNT_SHARED())
*is* possible - it means that we have allocated group id, but didn't
get around to set_mnt_shared() yet; such state is transient -
by the time we do namespace_unlock(), we must either do set_mnt_shared()
or unroll the group id allocations by cleanup_group_ids().

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