This merge request includes the dax-4.0-iomap-pmd branch which is

needed for both ext4 and xfs dax changes to use iomap for DAX.  It
 also includes the fscrypt branch which is needed for ubifs encryption
 work as well as ext4 encryption and fscrypt cleanups.
 
 Lots of cleanups and bug fixes, especially making sure ext4 is robust
 against maliciously corrupted file systems --- especially maliciously
 corrupted xattr blocks and a maliciously corrupted superblock.  Also
 fix ext4 support for 64k block sizes so it works well on ppcle.  Fixed
 mbcache so we don't miss some common xattr blocks that can be merged.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
 "This merge request includes the dax-4.0-iomap-pmd branch which is
  needed for both ext4 and xfs dax changes to use iomap for DAX. It also
  includes the fscrypt branch which is needed for ubifs encryption work
  as well as ext4 encryption and fscrypt cleanups.

  Lots of cleanups and bug fixes, especially making sure ext4 is robust
  against maliciously corrupted file systems --- especially maliciously
  corrupted xattr blocks and a maliciously corrupted superblock. Also
  fix ext4 support for 64k block sizes so it works well on ppcle. Fixed
  mbcache so we don't miss some common xattr blocks that can be merged"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (86 commits)
  dax: Fix sleep in atomic contex in grab_mapping_entry()
  fscrypt: Rename FS_WRITE_PATH_FL to FS_CTX_HAS_BOUNCE_BUFFER_FL
  fscrypt: Delay bounce page pool allocation until needed
  fscrypt: Cleanup page locking requirements for fscrypt_{decrypt,encrypt}_page()
  fscrypt: Cleanup fscrypt_{decrypt,encrypt}_page()
  fscrypt: Never allocate fscrypt_ctx on in-place encryption
  fscrypt: Use correct index in decrypt path.
  fscrypt: move the policy flags and encryption mode definitions to uapi header
  fscrypt: move non-public structures and constants to fscrypt_private.h
  fscrypt: unexport fscrypt_initialize()
  fscrypt: rename get_crypt_info() to fscrypt_get_crypt_info()
  fscrypto: move ioctl processing more fully into common code
  fscrypto: remove unneeded Kconfig dependencies
  MAINTAINERS: fscrypto: recommend linux-fsdevel for fscrypto patches
  ext4: do not perform data journaling when data is encrypted
  ext4: return -ENOMEM instead of success
  ext4: reject inodes with negative size
  ext4: remove another test in ext4_alloc_file_blocks()
  Documentation: fix description of ext4's block_validity mount option
  ext4: fix checks for data=ordered and journal_async_commit options
  ...

Documentation/filesystems/dax.txt

@@ -58,22 +58,22 @@ Implementation Tips for Filesystem Writers
 Filesystem support consists of
 - adding support to mark inodes as being DAX by setting the S_DAX flag in
   i_flags
-- implementing the direct_IO address space operation, and calling
-  dax_do_io() instead of blockdev_direct_IO() if S_DAX is set
+- implementing ->read_iter and ->write_iter operations which use dax_iomap_rw()
+  when inode has S_DAX flag set
 - implementing an mmap file operation for DAX files which sets the
   VM_MIXEDMAP and VM_HUGEPAGE flags on the VMA, and setting the vm_ops to
-  include handlers for fault, pmd_fault and page_mkwrite (which should
-  probably call dax_fault(), dax_pmd_fault() and dax_mkwrite(), passing the
-  appropriate get_block() callback)
-- calling dax_truncate_page() instead of block_truncate_page() for DAX files
-- calling dax_zero_page_range() instead of zero_user() for DAX files
+  include handlers for fault, pmd_fault, page_mkwrite, pfn_mkwrite. These
+  handlers should probably call dax_iomap_fault() (for fault and page_mkwrite
+  handlers), dax_iomap_pmd_fault(), dax_pfn_mkwrite() passing the appropriate
+  iomap operations.
+- calling iomap_zero_range() passing appropriate iomap operations instead of
+  block_truncate_page() for DAX files
 - ensuring that there is sufficient locking between reads, writes,
   truncates and page faults
 
-The get_block() callback passed to the DAX functions may return
-uninitialised extents.  If it does, it must ensure that simultaneous
-calls to get_block() (for example by a page-fault racing with a read()
-or a write()) work correctly.
+The iomap handlers for allocating blocks must make sure that allocated blocks
+are zeroed out and converted to written extents before being returned to avoid
+exposure of uninitialized data through mmap.
 
 These filesystems may be used for inspiration:
 - ext2: see Documentation/filesystems/ext2.txt

Documentation/filesystems/ext4.txt

@@ -351,14 +351,13 @@ nouid32			Disables 32-bit UIDs and GIDs.  This is for
 			interoperability  with  older kernels which only
 			store and expect 16-bit values.
 
-block_validity		This options allows to enables/disables the in-kernel
+block_validity(*)	These options enable or disable the in-kernel
 noblock_validity	facility for tracking filesystem metadata blocks
-			within internal data structures. This allows multi-
-			block allocator and other routines to quickly locate
-			extents which might overlap with filesystem metadata
-			blocks. This option is intended for debugging
-			purposes and since it negatively affects the
-			performance, it is off by default.
+			within internal data structures.  This allows multi-
+			block allocator and other routines to notice
+			bugs or corrupted allocation bitmaps which cause
+			blocks to be allocated which overlap with
+			filesystem metadata blocks.
 
 dioread_lock		Controls whether or not ext4 should use the DIO read
 dioread_nolock		locking. If the dioread_nolock option is specified