This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph.  This
is mostly a matter of moving files around.  However, a few key pieces
of the interface change as well:

 - ceph_client becomes ceph_fs_client and ceph_client, where the latter
   captures the mon and osd clients, and the fs_client gets the mds client
   and file system specific pieces.
 - Mount option parsing and debugfs setup is correspondingly broken into
   two pieces.
 - The mon client gets a generic handler callback for otherwise unknown
   messages (mds map, in this case).
 - The basic supported/required feature bits can be expanded (and are by
   ceph_fs_client).

No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.

Signed-off-by: Sage Weil <sage@newdream.net>

Sending multiple flushsnap messages is problematic because we ignore
the response if the tid doesn't match, and the server may only respond to
each one once.  It's also a waste.

So, skip cap_snaps that are already on the flushing list, unless the caller
tells us to resend (because we are reconnecting).

Signed-off-by: Sage Weil <sage@newdream.net>

The cap_snap creation/queueing relies on both the current i_head_snapc
_and_ the i_snap_realm pointers being correct, so that the new cap_snap
can properly reference the old context and the new i_head_snapc can be
updated to reference the new snaprealm's context.  To fix this, we:

 - move inodes completely to the new (split) realm so that i_snap_realm
   is correct, and
 - generate the new snapc's _before_ queueing the cap_snaps in
   ceph_update_snap_trace().

Signed-off-by: Sage Weil <sage@newdream.net>

The 'follows' should match the seq for the snap context for the given snap
cap, which is the context under which we have been dirtying and writing
data and metadata.  The snapshot that _contains_ those updates thus
_follows_ that context's seq #.

Signed-off-by: Sage Weil <sage@newdream.net>

We used to use i_head_snapc to keep track of which snapc the current epoch
of dirty data was dirtied under.  It is used by queue_cap_snap to set up
the cap_snap.  However, since we queue cap snaps for any dirty caps, not
just for dirty file data, we need to keep a valid i_head_snapc anytime
we have dirty|flushing caps.  This fixes a NULL pointer deref in
queue_cap_snap when writing back dirty caps without data (e.g.,
snaptest-authwb.sh).

Signed-off-by: Sage Weil <sage@newdream.net>

When a realm is updated, we need to queue writeback on inodes in that
realm _and_ its children.  Otherwise, if the inode gets cowed on the
server, we can get a hang later due to out-of-sync cap/snap state.

Signed-off-by: Sage Weil <sage@newdream.net>

When we snapshot dirty metadata that needs to be written back to the MDS,
include dirty xattr metadata.  Make the capsnap reference the encoded
xattr blob so that it will be written back in the FLUSHSNAP op.

Also fix the capsnap creation guard to include dirty auth or file bits,
not just tests specific to dirty file data or file writes in progress
(this fixes auth metadata writeback).

Signed-off-by: Sage Weil <sage@newdream.net>

ceph_sb_to_client and ceph_client are really identical, we need to dump
one; while function ceph_client is confusing with "struct ceph_client",
ceph_sb_to_client's definition is more clear; so we'd better switch all
call to ceph_sb_to_client.

  -static inline struct ceph_client *ceph_client(struct super_block *sb)
  -{
  -	return sb->s_fs_info;
  -}

Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>

The snap realm split was checking i_snap_realm, not the list_head, to
determine if an inode belonged in the new realm.  The check always failed,
which meant we always moved the inode, corrupting the old realm's list and
causing various crashes.

Also wait to release old realm reference to avoid possibility of use after
free.

Signed-off-by: Sage Weil <sage@newdream.net>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: use separate class for ceph sockets' sk_lock
  ceph: reserve one more caps space when doing readdir
  ceph: queue_cap_snap should always queue dirty context
  ceph: fix dentry reference leak in dcache readdir
  ceph: decode v5 of osdmap (pool names) [protocol change]
  ceph: fix ack counter reset on connection reset
  ceph: fix leaked inode ref due to snap metadata writeback race
  ceph: fix snap context reference leaks
  ceph: allow writeback of snapped pages older than 'oldest' snapc
  ceph: fix dentry rehashing on virtual .snap dir