linux.git/fs/notify/dnotify, branch v6.8

fs: Remove the now superfluous sentinel elements from ctl_table array

2023-12-28T12:57:57+00:00

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados 
Reviewed-by: Jan Kara 
Reviewed-by: "Darrick J. Wong" 
Acked-by: Christian Brauner 
Signed-off-by: Luis Chamberlain

Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-11-03T06:53:31+00:00

Pull non-MM updates from Andrew Morton:
 "As usual, lots of singleton and doubleton patches all over the tree
  and there's little I can say which isn't in the individual changelogs.

  The lengthier patch series are

   - 'kdump: use generic functions to simplify crashkernel reservation
     in arch', from Baoquan He. This is mainly cleanups and
     consolidation of the 'crashkernel=' kernel parameter handling

   - After much discussion, David Laight's 'minmax: Relax type checks in
     min() and max()' is here. Hopefully reduces some typecasting and
     the use of min_t() and max_t()

   - A group of patches from Oleg Nesterov which clean up and slightly
     fix our handling of reads from /proc/PID/task/... and which remove
     task_struct.thread_group"

* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
  scripts/gdb/vmalloc: disable on no-MMU
  scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
  .mailmap: add address mapping for Tomeu Vizoso
  mailmap: update email address for Claudiu Beznea
  tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
  .mailmap: map Benjamin Poirier's address
  scripts/gdb: add lx_current support for riscv
  ocfs2: fix a spelling typo in comment
  proc: test ProtectionKey in proc-empty-vm test
  proc: fix proc-empty-vm test with vsyscall
  fs/proc/base.c: remove unneeded semicolon
  do_io_accounting: use sig->stats_lock
  do_io_accounting: use __for_each_thread()
  ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
  ocfs2: fix a typo in a comment
  scripts/show_delta: add __main__ judgement before main code
  treewide: mark stuff as __ro_after_init
  fs: ocfs2: check status values
  proc: test /proc/${pid}/statm
  compiler.h: move __is_constexpr() to compiler.h
  ...

file: convert to SLAB_TYPESAFE_BY_RCU

2023-10-19T09:02:48+00:00

In recent discussions around some performance improvements in the file
handling area we discussed switching the file cache to rely on
SLAB_TYPESAFE_BY_RCU which allows us to get rid of call_rcu() based
freeing for files completely. This is a pretty sensitive change overall
but it might actually be worth doing.

The main downside is the subtlety. The other one is that we should
really wait for Jann's patch to land that enables KASAN to handle
SLAB_TYPESAFE_BY_RCU UAFs. Currently it doesn't but a patch for this
exists.

With SLAB_TYPESAFE_BY_RCU objects may be freed and reused multiple times
which requires a few changes. So it isn't sufficient anymore to just
acquire a reference to the file in question under rcu using
atomic_long_inc_not_zero() since the file might have already been
recycled and someone else might have bumped the reference.

In other words, callers might see reference count bumps from newer
users. For this reason it is necessary to verify that the pointer is the
same before and after the reference count increment. This pattern can be
seen in get_file_rcu() and __files_get_rcu().

In addition, it isn't possible to access or check fields in struct file
without first aqcuiring a reference on it. Not doing that was always
very dodgy and it was only usable for non-pointer data in struct file.
With SLAB_TYPESAFE_BY_RCU it is necessary that callers first acquire a
reference under rcu or they must hold the files_lock of the fdtable.
Failing to do either one of this is a bug.

Thanks to Jann for pointing out that we need to ensure memory ordering
between reallocations and pointer check by ensuring that all subsequent
loads have a dependency on the second load in get_file_rcu() and
providing a fixup that was folded into this patch.

Cc: Jann Horn 
Suggested-by: Linus Torvalds 
Signed-off-by: Christian Brauner

treewide: mark stuff as __ro_after_init

2023-10-18T21:43:23+00:00

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

dnotify: Pass argument of fcntl_dirnotify as int

2023-07-10T12:36:12+00:00

The interface for fcntl expects the argument passed for the command
F_DIRNOTIFY to be of type int. The current code wrongly treats it as
a long. In order to avoid access to undefined bits, we should explicitly
cast the argument to int.

Cc: Jan Kara 
Cc: Amir Goldstein 
Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Jeff Layton 
Cc: Chuck Lever 
Cc: Kevin Brodsky 
Cc: Vincenzo Frascino 
Cc: Szabolcs Nagy 
Cc: "Theodore Ts'o" 
Cc: David Laight 
Cc: Mark Rutland 
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-morello@op-lists.linaro.org
Acked-by: Jan Kara 
Signed-off-by: Luca Vizzarro 
Message-Id: <20230414152459.816046-6-Luca.Vizzarro@arm.com>
Signed-off-by: Christian Brauner

dnotify: use fsnotify group lock helpers

2022-04-25T12:37:34+00:00

Before commit 9542e6a643fc6 ("nfsd: Containerise filecache laundrette")
nfsd would close open files in direct reclaim context.  There is no
guarantee that others memory shrinkers don't do the same and no
guarantee that future shrinkers won't do that.

For example, if overlayfs implements inode cache of fscache would
keep open files to cached objects, inode shrinkers could end up closing
open files to underlying fs.

Direct reclaim from dnotify mark allocation context may try to close
open files that have dnotify marks of the same group and hit a deadlock
on mark_mutex.

Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim
from allocations under dnotify group lock and use the safe group lock
helpers.

Link: https://lore.kernel.org/r/20220422120327.3459282-11-amir73il@gmail.com
Suggested-by: Jan Kara 
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: pass flags argument to fsnotify_alloc_group()

2022-04-25T12:37:12+00:00

Add flags argument to fsnotify_alloc_group(), define and use the flag
FSNOTIFY_GROUP_USER in inotify and fanotify instead of the helper
fsnotify_alloc_user_group() to indicate user allocation.

Although the flag FSNOTIFY_GROUP_USER is currently not used after group
allocation, we store the flags argument in the group struct for future
use of other group flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

dnotify: move dnotify sysctl to dnotify.c

2022-01-22T06:33:34+00:00

The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

So move dnotify sysctls to dnotify.c and use the new
register_sysctl_init() to register the sysctl interface.

[mcgrof@kernel.org: adjust the commit log to justify the move]

Link: https://lkml.kernel.org/r/20211123202347.818157-10-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni 
Signed-off-by: Luis Chamberlain 
Acked-by: Jan Kara 
Cc: Al Viro 
Cc: Amir Goldstein 
Cc: Andy Shevchenko 
Cc: Benjamin LaHaise 
Cc: "Eric W. Biederman" 
Cc: Greg Kroah-Hartman 
Cc: Iurii Zaikin 
Cc: Kees Cook 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Qing Wang 
Cc: Sebastian Reichel 
Cc: Sergey Senozhatsky 
Cc: Stephen Kitt 
Cc: Tetsuo Handa 
Cc: Antti Palosaari 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Clemens Ladisch 
Cc: David Airlie 
Cc: Jani Nikula 
Cc: Joel Becker 
Cc: Joonas Lahtinen 
Cc: Joseph Qi 
Cc: Julia Lawall 
Cc: Lukas Middendorf 
Cc: Mark Fasheh 
Cc: Phillip Potter 
Cc: Rodrigo Vivi 
Cc: Douglas Gilbert 
Cc: James E.J. Bottomley 
Cc: Jani Nikula 
Cc: John Ogness 
Cc: Martin K. Petersen 
Cc: "Rafael J. Wysocki" 
Cc: Steven Rostedt (VMware) 
Cc: Suren Baghdasaryan 
Cc: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fsnotify: generate FS_RENAME event with rich information

2021-12-15T13:04:27+00:00

The dnotify FS_DN_RENAME event is used to request notification about
a move within the same parent directory and was always coupled with
the FS_MOVED_FROM event.

Rename the FS_DN_RENAME event flag to FS_RENAME, decouple it from
FS_MOVED_FROM and report it with the moved dentry instead of the moved
inode, so it has the information about both old and new parent and name.

Generate the FS_RENAME event regardless of same parent dir and apply
the "same parent" rule in the generic fsnotify_handle_event() helper
that is used to call backends with ->handle_inode_event() method
(i.e. dnotify).  The ->handle_inode_event() method is not rich enough to
report both old and new parent and name anyway.

The enriched event is reported to fanotify over the ->handle_event()
method with the old and new dir inode marks in marks array slots for
ITER_TYPE_INODE and a new iter type slot ITER_TYPE_INODE2.

The enriched event will be used for reporting old and new parent+name to
fanotify groups with FAN_RENAME events.

Link: https://lore.kernel.org/r/20211129201537.1932819-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

Merge tag 'fsnotify_for_v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2020-12-17T18:56:27+00:00

Pull fsnotify updates from Jan Kara:
 "A few fsnotify fixes from Amir fixing fallout from big fsnotify
  overhaul a few months back and an improvement of defaults limiting
  maximum number of inotify watches from Waiman"

* tag 'fsnotify_for_v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: fix events reported to watching parent and child
  inotify: convert to handle_inode_event() interface
  fsnotify: generalize handle_inode_event()
  inotify: Increase default inotify.max_user_watches limit to 1048576