[v2,0/2] erofs: dio/dax support for non-tailpacking cases

Message

Gao Xiang July 12, 2021, 12:02 p.m. UTC

Hi folks,

This patchset mainly adds preliminary EROFS iomap dio/dax support
for non-tailpacking uncompressed cases.

Direct I/O is useful in certain scenarios for uncompressed files.
For example, double pagecache can be avoid by direct I/O when
loop device is used for uncompressed files containing upper layer
compressed filesystem.

Also, DAX is quite useful for some VM use cases in order to
save guest memory extremely by using the minimal lightweight EROFS.

Tail-packing inline iomap support will be handled later since
currently iomap doesn't support such data pattern, which is
independent to non-tailpacking cases.

Comments are welcome. Thanks for your time on reading this!

Thanks,
Gao Xiang

changes since v1:
 - allow 'dax=always' and 'dax=never' to keep in sync with ext4/xfs

Gao Xiang (1):
  erofs: dax support for non-tailpacking regular file

Huang Jianan (1):
  erofs: iomap support for non-tailpacking DIO

 fs/erofs/Kconfig    |   1 +
 fs/erofs/data.c     | 142 +++++++++++++++++++++++++++++++++++++++++++-
 fs/erofs/inode.c    |   9 ++-
 fs/erofs/internal.h |   4 ++
 fs/erofs/super.c    |  60 ++++++++++++++++++-
 5 files changed, 212 insertions(+), 4 deletions(-)