Pull ceph updates from Ilya Dryomov:
 "A varied set of changes:

   - a large rework of cephx auth code to cope with CONFIG_VMAP_STACK
     (myself). Also fixed a deadlock caused by a bogus allocation on the
     writeback path and authorize reply verification.

   - a fix for long stalls during fsync (Jeff Layton). The client now
     has a way to force the MDS log flush, leading to ~100x speedups in
     some synthetic tests.

   - a new [no]require_active_mds mount option (Zheng Yan).

     On mount, we will now check whether any of the MDSes are available
     and bail rather than block if none are. This check can be avoided
     by specifying the "no" option.

   - a couple of MDS cap handling fixes and a few assorted patches
     throughout"

* tag 'ceph-for-4.10-rc1' of git://github.com/ceph/ceph-client: (32 commits)
  libceph: remove now unused finish_request() wrapper
  libceph: always signal completion when done
  ceph: avoid creating orphan object when checking pool permission
  ceph: properly set issue_seq for cap release
  ceph: add flags parameter to send_cap_msg
  ceph: update cap message struct version to 10
  ceph: define new argument structure for send_cap_msg
  ceph: move xattr initialzation before the encoding past the ceph_mds_caps
  ceph: fix minor typo in unsafe_request_wait
  ceph: record truncate size/seq for snap data writeback
  ceph: check availability of mds cluster on mount
  ceph: fix splice read for no Fc capability case
  ceph: try getting buffer capability for readahead/fadvise
  ceph: fix scheduler warning due to nested blocking
  ceph: fix printing wrong return variable in ceph_direct_read_write()
  crush: include mapper.h in mapper.c
  rbd: silence bogus -Wmaybe-uninitialized warning
  libceph: no need to drop con->mutex for ->get_authorizer()
  libceph: drop len argument of *verify_authorizer_reply()
  libceph: verify authorize reply on connect
  ...

Dirty snapshot data needs to be flushed unconditionally. If they
were created before truncation, writeback should use old truncate
size/seq.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

Signed-off-by: Yan, Zheng <zyan@redhat.com>

For readahead/fadvise cases, caller of ceph_readpages does not
hold buffer capability. Pages can be added to page cache while
there is no buffer capability. This can cause data integrity
issue.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Add a 'wake' flag to ceph_cap_flush struct, which indicates if there
is someone waiting for it to finish. When getting flush ack message,
we check the 'wake' flag in corresponding ceph_cap_flush struct to
decide if we should wake up waiters. One corner case is that the
acked cap flush has 'wake' flags is set, but it is not the first one
on the flushing list. We do not wake up waiters in this case, set
'wake' flags of preceding ceph_cap_flush struct instead

Signed-off-by: Yan, Zheng <zyan@redhat.com>

This patch devide __ceph_flush_snaps() into two stags. In the first
stage, __ceph_flush_snaps() assign snapcaps flush TIDs and add them
to cap flush lists. __ceph_flush_snaps() keeps holding the
i_ceph_lock in this stagge. So inode's auth cap can not change. In
the second stage, __ceph_flush_snaps() send flushsnap cap messages.
i_ceph_lock is unlocked before sending each cap message. If auth cap
changes in the middle, __ceph_flush_snaps() just stops. This is OK
because kick_flushing_inode_caps() will re-send flushsnap cap messages
to inode's new auth MDS.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

Signed-off-by: Yan, Zheng <zyan@redhat.com>

make ceph_kick_flushing_caps() ignore inodes whose cap flushes
have already been re-sent by ceph_early_kick_flushing_caps()

Signed-off-by: Yan, Zheng <zyan@redhat.com>