Commit 9748cb2dc393 ("VFS: repack DENTRY_ flags.") changed the value of
DCACHE_MOUNTED, which broke drgn's path_lookup() helper. drgn is forced
to hard-code it because it's a macro, and macros aren't preserved in
debugging information by default.

Enums, on the other hand, are included in debugging information. Convert
the DCACHE_* flag macros to an enum so that debugging tools like drgn
and bpftrace can make use of them.

Link: https://github.com/osandov/drgn/blob/2027d0fea84d74b835e77392f7040c2a333180c6/drgn/helpers/linux/fs.py#L43-L46
Signed-off-by: Omar Sandoval <osandov@fb.com>
Link: https://lore.kernel.org/177665a082f048cf536b9cd6af467b3be6b6e6ed.1744141838.git.osandov@fb.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Pull sysctl updates from Joel Granados:

 - Move vm_table members out of kernel/sysctl.c

   All vm_table array members have moved to their respective subsystems
   leading to the removal of vm_table from kernel/sysctl.c. This
   increases modularity by placing the ctl_tables closer to where they
   are actually used and at the same time reducing the chances of merge
   conflicts in kernel/sysctl.c.

 - ctl_table range fixes

   Replace the proc_handler function that checks variable ranges in
   coredump_sysctls and vdso_table with the one that actually uses the
   extra{1,2} pointers as min/max values. This tightens the range of the
   values that users can pass into the kernel effectively preventing
   {under,over}flows.

 - Misc fixes

   Correct grammar errors and typos in test messages. Update sysctl
   files in MAINTAINERS. Constified and removed array size in
   declaration for alignment_tbl

* tag 'sysctl-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: (22 commits)
  selftests/sysctl: fix wording of help messages
  selftests: fix spelling/grammar errors in sysctl/sysctl.sh
  MAINTAINERS: Update sysctl file list in MAINTAINERS
  sysctl: Fix underflow value setting risk in vm_table
  coredump: Fixes core_pipe_limit sysctl proc_handler
  sysctl: remove unneeded include
  sysctl: remove the vm_table
  sh: vdso: move the sysctl to arch/sh/kernel/vsyscall/vsyscall.c
  x86: vdso: move the sysctl to arch/x86/entry/vdso/vdso32-setup.c
  fs: dcache: move the sysctl to fs/dcache.c
  sunrpc: simplify rpcauth_cache_shrink_count()
  fs: drop_caches: move sysctl to fs/drop_caches.c
  fs: fs-writeback: move sysctl to fs/fs-writeback.c
  mm: nommu: move sysctl to mm/nommu.c
  security: min_addr: move sysctl to security/min_addr.c
  mm: mmap: move sysctl to mm/mmap.c
  mm: util: move sysctls to mm/util.c
  mm: vmscan: move vmscan sysctls to mm/vmscan.c
  mm: swap: move sysctl to mm/swap.c
  mm: filemap: move sysctl to mm/filemap.c
  ...

NeilBrown <neilb@suse.de> says:

These two patches are cleanup are dependencies for my mkdir changes and
subsequence directory locking changes.

* patches from https://lore.kernel.org/r/20250226062135.2043651-1-neilb@suse.de: (2 commits)
  nfsd: drop fh_update() from S_IFDIR branch of nfsd_create_locked()
  nfs/vfs: discard d_exact_alias()

Link: https://lore.kernel.org/r/20250226062135.2043651-1-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>

d_exact_alias() is a descendent of d_add_unique() which was introduced
20 years ago mostly likely to work around problems with NFS servers of
the time.  It is now not used in several situations were it was
originally needed and there have been no reports of problems -
presumably the old NFS servers have been improved.  This only place it
is now use is in NFSv4 code and the old problematic servers are thought
to have been v2/v3 only.

There is no clear benefit in reusing a unhashed() dentry which happens
to have the same name as the dentry we are adding.

So this patch removes d_exact_alias() and the one place that it is used.

Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250226062135.2043651-2-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>

Bits 13, 23, 24, and 27 are not used.  Move all those holes to the end.

Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250206054504.2950516-7-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>

The sysctl_vfs_cache_pressure belongs to fs/dcache.c, move it to
fs/dcache.c from kernel/sysctl.c. As a part of fs/dcache.c cleaning,
sysctl_vfs_cache_pressure is changed to a static variable, and change
the inline-type function vfs_pressure_ratio() to out-of-inline type,
export vfs_pressure_ratio() with EXPORT_SYMBOL_GPL to be used by other
files. Move the unneeded include(linux/dcache.h).

Signed-off-by: Kaixiong Yu <yukaixiong@huawei.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>

Pull misc vfs cleanups from Al Viro:
 "Two unrelated patches - one is a removal of long-obsolete include in
  overlayfs (it used to need fs/internal.h, but the extern it wanted has
  been moved back to include/linux/namei.h) and another introduces
  convenience helper constructing struct qstr by a NUL-terminated
  string"

* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  add a string-to-qstr constructor
  fs/overlayfs/namei.c: get rid of include ../internal.h

Quite a few places want to build a struct qstr by given string;
it would be convenient to have a primitive doing that, rather
than open-coding it via QSTR_INIT().

The closest approximation was in bcachefs, but that expands to
initializer list - {.len = strlen(string), .name = string}.
It would be more useful to have it as compound literal -
(struct qstr){.len = strlen(string), .name = string}.

Unlike initializer list it's a valid expression.  What's more,
it's a valid lvalue - it's an equivalent of anonymous local
variable with such initializer, so the things like
	path->dentry = d_alloc_pseudo(mnt->mnt_sb, &QSTR(name));
are valid.  It can also be used as initializer, with identical
effect -
	struct qstr x = (struct qstr){.name = s, .len = strlen(s)};
is equivalent to
	struct qstr anon_variable = {.name = s, .len = strlen(s)};
	struct qstr x = anon_variable;
	// anon_variable is never used after that point
and any even remotely sane compiler will manage to collapse that
into
	struct qstr x = {.name = s, .len = strlen(s)};

What compound literals can't be used for is initialization of
global variables, but those are covered by QSTR_INIT().

This commit lifts definition(s) of QSTR() into linux/dcache.h,
converts it to compound literal (all bcachefs users are fine
with that) and converts assorted open-coded instances to using
that.

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

9p wants to be able to build a path from given dentry to fs root and keep
it valid over a blocking operation.

->s_vfs_rename_mutex would be a natural candidate, but there are places
where we need that and where we have no way to tell if ->s_vfs_rename_mutex
is already held deeper in callchain.  Moreover, it's only held for
cross-directory renames; name changes within the same directory happen
without it.

Solution:
	* have d_move() done in ->rename() rather than in its caller
	* maintain a 9p-private rwsem (per-filesystem)
	* hold it exclusive over the relevant part of ->rename()
	* hold it shared over the places where we want the path.

That almost works.  FS_RENAME_DOES_D_MOVE is enough to put all d_move()
and d_exchange() calls under filesystem's control.  However, there's
also __d_unalias(), which isn't covered by any of that.

If ->lookup() hits a directory inode with preexisting dentry elsewhere
(due to e.g. rename done on server behind our back), d_splice_alias()
called by ->lookup() will move/rename that alias.

Add a couple of optional methods, so that __d_unalias() would do
	if alias->d_op->d_unalias_trylock != NULL
		if (!alias->d_op->d_unalias_trylock(alias))
			fail (resulting in -ESTALE from lookup)
	__d_move(...)
	if alias->d_op->d_unalias_unlock != NULL
		alias->d_unalias_unlock(alias)
where it currently does __d_move().  9p instances do down_write_trylock()
and up_write() of ->rename_mutex.

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

->d_revalidate() often needs to access dentry parent and name; that has
to be done carefully, since the locking environment varies from caller
to caller.  We are not guaranteed that dentry in question will not be
moved right under us - not unless the filesystem is such that nothing
on it ever gets renamed.

It can be dealt with, but that results in boilerplate code that isn't
even needed - the callers normally have just found the dentry via dcache
lookup and want to verify that it's in the right place; they already
have the values of ->d_parent and ->d_name stable.  There is a couple
of exceptions (overlayfs and, to less extent, ecryptfs), but for the
majority of calls that song and dance is not needed at all.

It's easier to make ecryptfs and overlayfs find and pass those values if
there's a ->d_revalidate() instance to be called, rather than doing that
in the instances.

This commit only changes the calling conventions; making use of supplied
values is left to followups.

NOTE: some instances need more than just the parent - things like CIFS
may need to build an entire path from filesystem root, so they need
more precautions than the usual boilerplate.  This series doesn't
do anything to that need - these filesystems have to keep their locking
mechanisms (rename_lock loops, use of dentry_path_raw(), private rwsem
a-la v9fs).

One thing to keep in mind when using name is that name->name will normally
point into the pathname being resolved; the filename in question occupies
name->len bytes starting at name->name, and there is NUL somewhere after it,
but it the next byte might very well be '/' rather than '\0'.  Do not
ignore name->len.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gabriel Krisman Bertazi <gabriel@krisman.be>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>