mds: preserve subtree bounds until slave commit

When replaying an operation that rename a directory inode to non-auth subtree,
if the inode has subtree bounds, we should prevent them from being trimmed
until slave commit.

This patch also fixes a bug in ESlaveUpdate::replay(). EMetaBlob::replay()
should be called before MDCache::finish_uncommitted_slave_update().

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: process finished contexts in batch

If there are several unstable locks in an inode, current Locker::eval(CInode*,)
processes each lock's finished contexts seperately. This may cause very deep
call stack if finished contexts also call Locker::eval() on the same inode.
An extreme example is:

Locker::eval() wakes an open request(). Server::handle_client_open() starts
a log entry, then call Locker::issue_new_caps(). Locker::issue_new_caps()
calls Locker::eval() and wakes another request. The later request also tries
starting a log entry.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: fix MDCache::adjust_bounded_subtree_auth()

There are cases that need both create new bound and swallow intervening
subtree. For example: A MDS exports subtree A with bound B and imports
subtree B with bound C at the same time. The MDS crashes, exporting
subtree A fails, but importing subtree B succeed. During recovery, the
MDS may create new bound C and swallow subtree B.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: mark connection down when MDS fails

So if the MDS restarts and uses the same address, it does not get
old messages.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: consider MDS as recovered when it reaches clientreplay state.

MDS in clientreplsy state already starts servering requests. It also
make MDS::handle_mds_recovery() and MDS::recovery_done() match.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: make sure table request id unique

When a MDS becomes active, the table server re-sends 'agree' messages
for old prepared request. If the recoverd MDS starts a new table request
at the same time, The new request's ID can happen to be the same as old
prepared request's ID, because current table client code assigns request
ID from zero after MDS restarts.

This patch make table server send 'ready' messages when table clients
become active or itself becomes active. The 'ready' message updates
table client's last_reqid to avoid request ID collision. The message
also replaces the roles of finish_recovery() and handle_mds_recovery()
callbacks for table client.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: avoid sending duplicated table prepare/commit

This patch makes table client defer sending table prepare/commit messages
until receiving table server's 'ready' message. This avoid duplicated table
prepare/commit messages.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: defer eval gather locks when removing replica

Locks' states should not change between composing the cache rejoin ack
messages and sending the message. If Locker::eval_gather() is called
in MDCache::{inode,dentry}_remove_replica(), it may wake requests and
change locks' states.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: unify slave request waiting

When requesting remote xlock or remote wrlock, the master request is
put into lock object's REMOTEXLOCK waiting queue. The problem is that
remote wrlock's target can be different from lock's auth MDS. When
the lock's auth MDS recovers, MDCache::handle_mds_recovery() may wake
incorrect request. So just unify slave request waiting, dispatch the
master request when receiving slave request reply.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
mds: don't delay processing replica buffer in slave request

Replicated objects need to be added into the cache immediately

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: compose and send resolve messages in batch

Resolve messages for all MDS are the same, so we can compose and
send them in batch.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: don't send resolve message between active MDS

When MDS cluster is resolving, current behavior is sending subtree resolve
message to all other MDS and waiting for all other MDS' resolve message.
The problem is that active MDS can have diffent subtree map due to rename.
Besides gathering active MDS's resolve messages are also racy. The only
function for these messages is disambiguate other MDS' import. We can
replace it by import finish notification.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: set resolve/rejoin gather MDS set in advance

For active MDS, it may receive resolve/rejoin message before receiving
the mdsmap message that claims the MDS cluster is in resolving/rejoning
state. So instead of set the gather MDS set when receiving the mdsmap.
set them in advance when detecting MDS' failure.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: don't send MDentry{Link,Unlink} before receiving cache rejoin

The active MDS calls MDCache::rejoin_scour_survivor_replicas() when it
receives the cache rejoin message. The function will remove the objects
replicated by MDentry{Link,Unlink} from replica map.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: send cache rejoin messages after gathering all resolves

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: send resolve acks after master updates are safely logged

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: fix MDS recovery involving cross authority rename

For mds cluster, rename operation may involve multiple MDS. If the
rename source's auth MDS crashes after some witness MDS have prepared
the rename but before the rename is committing. Later when the MDS
recovers, its subtree map and linkages are different from the prepared
MDS'. This causes problems for both subtree resolve and cache rejoin.
The solution is, if the rename source's auth MDS fails, the prepared
witness MDS query the master MDS if the operation is committing. If
it's not, rollback the rename, then send resolve message to the
recovering MDS.

Another similar case is a prepared witness MDS crashes when the
rename source's auth MDS has prepared or is preparing the operation.
when the witness recovers, the master just delay sending the resolve
ack message until the it commits the operation.

This patch also updates Server::handle_client_rename(). Make preparing
the rename source's auth MDS be the final step before committing the
rename.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: remove MDCache::rejoin_fetch_dirfrags()

In commit 77946dcdae (mds: fetch missing inodes from disk), I introduced
MDCache::rejoin_fetch_dirfrags(). But it basicly duplicates the function
of MDCache::open_undef_dirfrags(), so just remove rejoin_fetch_dirfrags()
and make open_undef_dirfrags() also handle undefined inodes.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: include replica nonce in MMDSCacheRejoin::inode_strong

So the recovering MDS can properly handle cache expire messages.
Also increase the nonce value when sending the cache rejoin acks.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>

Also update the MMDSCacheRejoin encoding to the new format.
Signed-off-by: Greg Farnum <greg@inktank.com>
mds: encode dirfrag base in cache rejoin ack

Cache rejoin ack message already encodes inode base, make it also encode
dirfrag base. This allowes the message to replicate stray dentries like
MDentryUnlink message. The function will be used by later patch.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>