Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

Pull fscrypt updates from Eric Biggers:
 "Add an ioctl FS_IOC_GET_ENCRYPTION_NONCE which retrieves a file's
  encryption nonce.

  This makes it easier to write automated tests which verify that
  fscrypt is doing the encryption correctly"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  ubifs: wire up FS_IOC_GET_ENCRYPTION_NONCE
  f2fs: wire up FS_IOC_GET_ENCRYPTION_NONCE
  ext4: wire up FS_IOC_GET_ENCRYPTION_NONCE
  fscrypt: add FS_IOC_GET_ENCRYPTION_NONCE ioctl

Documentation/filesystems/fscrypt.rst

@@ -633,6 +633,17 @@ from a passphrase or other low-entropy user credential.
 FS_IOC_GET_ENCRYPTION_PWSALT is deprecated.  Instead, prefer to
 generate and manage any needed salt(s) in userspace.
 
+Getting a file's encryption nonce
+---------------------------------
+
+Since Linux v5.7, the ioctl FS_IOC_GET_ENCRYPTION_NONCE is supported.
+On encrypted files and directories it gets the inode's 16-byte nonce.
+On unencrypted files and directories, it fails with ENODATA.
+
+This ioctl can be useful for automated tests which verify that the
+encryption is being done correctly.  It is not needed for normal use
+of fscrypt.
+
 Adding keys
 -----------