[RFC PATCH 0/5] libceph: add support for sparse reads to msgr2/crc

[Jeff Layton <jlayton@kernel.org>]

This is a first stab at a patchset to add support for sparse reads to
libceph. This is a prerequisite for fscrypt support, since we need to be
able to know whether a region is sparse in order to know whether we need
to decrypt it.

The patches basically work at this point, but it's still a RFC
for a few reasons:

1) the ms_mode=secure and ms_mode=legacy codepaths are not yet
supported. "legacy" doesn't look too bad, but "secure" is a bit
tougher, as I'd like to avoid extra buffering.

2) the OSD currently throws back -EINVAL on a sparse read if an extent
has a non-zero truncate_seq. I've opened this bug to request that this
be remedied: https://tracker.ceph.com/issues/54280

3) I'm not sure I got the revoke_at_* patch correct. I added a new field
to the v2_info structure. Maybe there is some better way to handle that?
What's the best way to test the revocation codepaths?

I ran this through xfstests yesterday, and several of them failed
because of #2 above, but it didn't oops!

Jeff Layton (5):
  libceph: allow ceph_msg_data_advance to advance more than a page
  libceph: add sparse read support to msgr2 crc state machine
  libceph: add sparse read support to OSD client
  libceph: add revoke support for sparse data
  ceph: switch to sparse reads

 fs/ceph/addr.c                  |   2 +-
 fs/ceph/file.c                  |   4 +-
 include/linux/ceph/messenger.h  |  20 ++++
 include/linux/ceph/osd_client.h |  37 ++++++
 net/ceph/messenger.c            |  12 +-
 net/ceph/messenger_v2.c         | 195 +++++++++++++++++++++++++++++---
 net/ceph/osd_client.c           | 161 +++++++++++++++++++++++++-
 7 files changed, 408 insertions(+), 23 deletions(-)

-- 
2.34.1