[v4,0/7] add support for direct I/O with fscrypt using blk-crypto

Message

Satya Tangirala July 20, 2020, 11:37 p.m. UTC

This patch series adds support for direct I/O with fscrypt using
blk-crypto. It has been rebased on fscrypt/master.

Patch 1 adds two functions to fscrypt that need to be called to determine
if direct I/O is supported for a request.

Patches 2 and 3 wire up direct-io and iomap respectively with the functions
introduced in Patch 1 and set bio crypt contexts on bios when appropriate
by calling into fscrypt.

Patches 4 and 5 allow ext4 and f2fs direct I/O to support fscrypt without
falling back to buffered I/O.

Patches 6 and 7 update the fscrypt documentation for inline encryption
support and direct I/O. The documentation now notes the required conditions
for inline encryption and direct I/O on encrypted files.

This patch series was tested by running xfstests with test_dummy_encryption
with and without the 'inlinecrypt' mount option, and there were no
meaningful regressions. One regression was for generic/587 on ext4,
but that test isn't compatible with test_dummy_encryption in the first
place, and the test "incorrectly" passes without the 'inlinecrypt' mount
option - a patch will be sent out to exclude that test when
test_dummy_encryption is turned on with ext4 (like the other quota related
tests that use user visible quota files). The other regression was for
generic/252 on ext4, which does direct I/O with a buffer aligned to the
block device's blocksize, but not necessarily aligned to the filesystem's
block size, which direct I/O with fscrypt requires.

Changes v3 => v4:
 - Fix bug in iomap_dio_bio_actor() where fscrypt_limit_io_pages() was
   being called too early (thanks Eric!)
 - Improve comments and fix formatting in documentation
 - iomap_dio_zero() is only called to zero out partial blocks, but
   direct I/O is only supported on encrypted files when I/O is
   blocksize aligned, so it doesn't need to set encryption contexts on
   bios. Replace setting the encryption context with a WARN_ON(). (Eric)

Changes v2 => v3:
 - add changelog to coverletter

Changes v1 => v2:
 - Fix bug in f2fs caused by replacing f2fs_post_read_required() with
   !fscrypt_dio_supported() since the latter doesn't check for
   compressed inodes unlike the former.
 - Add patches 6 and 7 for fscrypt documentation
 - cleanups and comments

Eric Biggers (5):
  fscrypt: Add functions for direct I/O support
  direct-io: add support for fscrypt using blk-crypto
  iomap: support direct I/O with fscrypt using blk-crypto
  ext4: support direct I/O with fscrypt using blk-crypto
  f2fs: support direct I/O with fscrypt using blk-crypto

Satya Tangirala (2):
  fscrypt: document inline encryption support
  fscrypt: update documentation for direct I/O support

 Documentation/filesystems/fscrypt.rst | 36 +++++++++++-
 fs/crypto/crypto.c                    |  8 +++
 fs/crypto/inline_crypt.c              | 82 +++++++++++++++++++++++++++
 fs/direct-io.c                        | 15 ++++-
 fs/ext4/file.c                        | 10 ++--
 fs/f2fs/f2fs.h                        |  6 +-
 fs/iomap/direct-io.c                  | 12 +++-
 include/linux/fscrypt.h               | 19 +++++++
 8 files changed, 178 insertions(+), 10 deletions(-)

Comments

Eric Biggers July 21, 2020, 12:56 a.m. UTC | #1

On Mon, Jul 20, 2020 at 11:37:32PM +0000, Satya Tangirala wrote:
> This patch series adds support for direct I/O with fscrypt using
> blk-crypto. It has been rebased on fscrypt/master.
> 
> Patch 1 adds two functions to fscrypt that need to be called to determine
> if direct I/O is supported for a request.
> 
> Patches 2 and 3 wire up direct-io and iomap respectively with the functions
> introduced in Patch 1 and set bio crypt contexts on bios when appropriate
> by calling into fscrypt.
> 
> Patches 4 and 5 allow ext4 and f2fs direct I/O to support fscrypt without
> falling back to buffered I/O.
> 
> Patches 6 and 7 update the fscrypt documentation for inline encryption
> support and direct I/O. The documentation now notes the required conditions
> for inline encryption and direct I/O on encrypted files.
> 
> This patch series was tested by running xfstests with test_dummy_encryption
> with and without the 'inlinecrypt' mount option, and there were no
> meaningful regressions. One regression was for generic/587 on ext4,
> but that test isn't compatible with test_dummy_encryption in the first
> place, and the test "incorrectly" passes without the 'inlinecrypt' mount
> option - a patch will be sent out to exclude that test when
> test_dummy_encryption is turned on with ext4 (like the other quota related
> tests that use user visible quota files). The other regression was for
> generic/252 on ext4, which does direct I/O with a buffer aligned to the
> block device's blocksize, but not necessarily aligned to the filesystem's
> block size, which direct I/O with fscrypt requires.
> 

This patch series looks good to me now.  Can the ext4, f2fs, and iomap
maintainers take a look?

- Eric