Pull dcache and mountpoint updates from Al Viro:
 "Saner handling of refcounts to mountpoints.

  Transfer the counting reference from struct mount ->mnt_mountpoint
  over to struct mountpoint ->m_dentry. That allows us to get rid of the
  convoluted games with ordering of mount shutdowns.

  The cost is in teaching shrink_dcache_{parent,for_umount} to cope with
  mixed-filesystem shrink lists, which we'll also need for the Slab
  Movable Objects patchset"

* 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch the remnants of releasing the mountpoint away from fs_pin
  get rid of detach_mnt()
  make struct mountpoint bear the dentry reference to mountpoint, not struct mount
  Teach shrink_dcache_parent() to cope with mixed-filesystem shrink lists
  fs/namespace.c: shift put_mountpoint() to callers of unhash_mnt()
  __detach_mounts(): lookup_mountpoint() can't return ERR_PTR() anymore
  nfs: dget_parent() never returns NULL
  ceph: don't open-code the check for dead lockref

Currently, running into a shrink list that contains dentries from different
filesystems can cause several unpleasant things for shrink_dcache_parent()
and for umount(2).

The first problem is that there's a window during shrink_dentry_list() between
__dentry_kill() takes a victim out and dropping reference to its parent.  During
that window the parent looks like a genuine busy dentry.  shrink_dcache_parent()
(or, worse yet, shrink_dcache_for_umount()) coming at that time will see no
eviction candidates and no indication that it needs to wait for some
shrink_dentry_list() to proceed further.

That applies for any shrink list that might intersect with the subtree we are
trying to shrink; the only reason it does not blow on umount(2) in the mainline
is that we unregister the memory shrinker before hitting shrink_dcache_for_umount().

Another problem happens if something in a mixed-filesystem shrink list gets
be stuck in e.g. iput(), getting umount of unrelated fs to spin waiting for
the stuck shrinker to get around to our dentries.

Solution:
        1) have shrink_dentry_list() decrement the parent's refcount and
make sure it's on a shrink list (ours unless it already had been on some
other) before calling __dentry_kill().  That eliminates the window when
shrink_dcache_parent() would've blown past the entire subtree without
noticing anything with zero refcount not on shrink lists.
	2) when shrink_dcache_parent() has found no eviction candidates,
but some dentries are still sitting on shrink lists, rather than
repeating the scan in hope that shrinkers have progressed, scan looking
for something on shrink lists with zero refcount.  If such a thing is
found, grab rcu_read_lock() and stop the scan, with caller locking
it for eviction, dropping out of RCU and doing __dentry_kill(), with
the same treatment for parent as shrink_dentry_list() would do.

Note that right now mixed-filesystem shrink lists do not occur, so this
is not a mainline bug.  Howevere, there's a bunch of uses for such
beasts (e.g. the "try and evict everything we can out of given page"
patches; there are potential uses in mount-related code, considerably
simplifying the life in fs/namespace.c, etc.)

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

d_delete() was piggy backed for the fsnotify_nameremove() hook when
in fact not all callers of d_delete() care about fsnotify events.

For all callers of d_delete() that may be interested in fsnotify events,
we made sure to call one of fsnotify_{unlink,rmdir}() hooks before
calling d_delete().

Now we can move the fsnotify_nameremove() call from d_delete() to the
fsnotify_{unlink,rmdir}() hooks.

Two explicit calls to fsnotify_nameremove() from nfs/afs sillyrename
are also removed. This will cause a change of behavior - nfs/afs will
NOT generate an fsnotify delete event when renaming over a positive
dentry.  This change is desirable, because it is consistent with the
behavior of all other filesystems.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull fscrypt updates from Ted Ts'o:
 "Clean up fscrypt's dcache revalidation support, and other
  miscellaneous cleanups"

* tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fscrypt: cache decrypted symlink target in ->i_link
  vfs: use READ_ONCE() to access ->i_link
  fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext
  fscrypt: only set dentry_operations on ciphertext dentries
  fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
  fscrypt: fix race allowing rename() and link() of ciphertext dentries
  fscrypt: clean up and improve dentry revalidation
  fscrypt: use READ_ONCE() to access ->i_crypt_info
  fscrypt: remove WARN_ON_ONCE() when decryption fails
  fscrypt: drop inode argument from fscrypt_get_ctx()

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

Make __d_move() clear DCACHE_ENCRYPTED_NAME on the source dentry.  This
is needed for when d_splice_alias() moves a directory's encrypted alias
to its decrypted alias as a result of the encryption key being added.

Otherwise, the decrypted alias will incorrectly be invalidated on the
next lookup, causing problems such as unmounting a mount the user just
mount()ed there.

Note that we don't have to support arbitrary moves of this flag because
fscrypt doesn't allow dentries with DCACHE_ENCRYPTED_NAME to be the
source or target of a rename().

Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key")
Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

No modular uses since introducion of alloc_file_pseudo(),
and the only non-modular user not in alloc_file_pseudo()
had actually been wrong - should've been d_alloc_anon().

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

For lockless accesses to dentries we don't have pinned we rely
(among other things) upon having an RCU delay between dropping
the last reference and actually freeing the memory.

On the other hand, for things like pipes and sockets we neither
do that kind of lockless access, nor want to deal with the
overhead of an RCU delay every time a socket gets closed.

So delay was made optional - setting DCACHE_RCUACCESS in ->d_flags
made sure it would happen.  We tried to avoid setting it unless
we knew we need it.  Unfortunately, that had led to recurring
class of bugs, in which we missed the need to set it.

We only really need it for dentries that are created by
d_alloc_pseudo(), so let's not bother with trying to be smart -
just make having an RCU delay the default.  The ones that do
*not* get it set the replacement flag (DCACHE_NORCU) and we'd
better use that sparingly.  d_alloc_pseudo() is the only
such user right now.

FWIW, the race that finally prompted that switch had been
between __lock_parent() of immediate subdirectory of what's
currently the root of a disconnected tree (e.g. from
open-by-handle in progress) racing with d_splice_alias()
elsewhere picking another alias for the same inode, either
on outright corrupted fs image, or (in case of open-by-handle
on NFS) that subdirectory having been just moved on server.
It's not easy to hit, so the sky is not falling, but that's
not the first race on similar missed cases and the logics
for settinf DCACHE_RCUACCESS has gotten ridiculously
convoluted.

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

The current dentry number tracking code doesn't distinguish between
positive & negative dentries.  It just reports the total number of
dentries in the LRU lists.

As excessive number of negative dentries can have an impact on system
performance, it will be wise to track the number of positive and
negative dentries separately.

This patch adds tracking for the total number of negative dentries in
the system LRU lists and reports it in the 5th field in the
/proc/sys/fs/dentry-state file.  The number, however, does not include
negative dentries that are in flight but not in the LRU yet as well as
those in the shrinker lists which are on the way out anyway.

The number of positive dentries in the LRU lists can be roughly found by
subtracting the number of negative dentries from the unused count.

Matthew Wilcox had confirmed that since the introduction of the
dentry_stat structure in 2.1.60, the dummy array was there, probably for
future extension.  They were not replacements of pre-existing fields.
So no sane applications that read the value of /proc/sys/fs/dentry-state
will do dummy thing if the last 2 fields of the sysctl parameter are not
zero.  IOW, it will be safe to use one of the dummy array entry for
negative dentry count.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>