[RFC PATCH 00/14] Consolidate Post read processing code

[Chandan Rajendra <chandan@linux.ibm.com>]

This patchset moves the "post read processing" code into a file of its
own (i.e. fs/post_read_process.c) and modifies the generic
do_mpage_readpge() to make use of the functionality provided. With
these changes in place, the patchset changes Ext4 to use
mpage_readpage[s] instead of its own custom ext4_readpage[s]()
functions. This is done to reduce duplicity of code across
filesystems. Also, Post read processing sources will be built only if
one of CONFIG_FS_ENCRYPTION and CONFIG_FS_VERITY is enabled.

Members of "struct fscrypt_ctx" that tracked status of a "write"
operation are now made an anonymous structure since the decryption
state tracking members are now moved into "struct post_read_ctx".

The patchset also modifies fs/buffer.c and fscrypt functionality to
get file encryption/decryption to work with subpage-sized blocks.

The following fixes from Eric Biggers are prerequisites for this
patchset,
  fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext
  fscrypt: only set dentry_operations on ciphertext dentries
  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

The patches can also be obtained from,
"https://github.com/chandanr/linux.git subpage-encryption"

TODO:
1. The subset of the fscrypt_encrypt_page() that deals with
   FS_CFLG_OWN_PAGES case still needs to be tested. UBIFS seems to be the
   only user of this piece of code.
2. Verity changes needs to be added for F2FS and I will add them in the
   next patchset based on the review comments obtained for the current
   patchset.

Chandan Rajendra (14):
  ext4: Clear BH_Uptodate flag on decryption error
  Consolidate "post read processing" into a new file
  fsverity: Add call back to decide if verity check has to be performed
  fsverity: Add call back to determine readpage limit
  fs/mpage.c: Integrate post read processing
  ext4: Wire up ext4_readpage[s] to use mpage_readpage[s]
  Remove the term "bio" from post read processing
  Add decryption support for sub-pagesized blocks
  ext4: Decrypt all boundary blocks when doing buffered write
  ext4: Decrypt the block that needs to be partially zeroed
  fscrypt_encrypt_page: Loop across all blocks mapped by a page range
  ext4: Compute logical block and the page range to be encrypted
  fscrypt_zeroout_range: Encrypt all zeroed out blocks of a page
  ext4: Enable encryption for subpage-sized blocks

 Documentation/filesystems/fscrypt.rst |   4 +-
 fs/Makefile                           |   4 +
 fs/buffer.c                           |  82 +++--
 fs/crypto/bio.c                       | 109 ++++---
 fs/crypto/crypto.c                    |  73 +++--
 fs/crypto/fscrypt_private.h           |   3 +
 fs/ext4/Makefile                      |   2 +-
 fs/ext4/ext4.h                        |   2 -
 fs/ext4/inode.c                       |  47 ++-
 fs/ext4/page-io.c                     |   9 +-
 fs/ext4/readpage.c                    | 445 --------------------------
 fs/ext4/super.c                       |  40 ++-
 fs/f2fs/data.c                        | 148 ++-------
 fs/f2fs/super.c                       |   9 +-
 fs/mpage.c                            |  45 ++-
 fs/post_read_process.c                | 155 +++++++++
 fs/verity/verify.c                    |  12 +
 include/linux/buffer_head.h           |   1 +
 include/linux/fscrypt.h               |  20 +-
 include/linux/fsverity.h              |   2 +
 include/linux/post_read_process.h     |  22 ++
 21 files changed, 503 insertions(+), 731 deletions(-)
 delete mode 100644 fs/ext4/readpage.c
 create mode 100644 fs/post_read_process.c
 create mode 100644 include/linux/post_read_process.h

-- 
2.19.1