Problem:
In the .t, when the only good brick was brought down, writes on the fd were
still succeeding on the bad bricks. The inflight split-brain check was
marking the write as failure but since the write succeeded on all the
bad bricks, afr_txn_nothing_failed() was set to true and we were
unwinding writev with success to DHT and then catching the failure in
post-op in the background.

Fix:
Don't wind the FOP phase if the write_subvol (which is populated with readable
subvols obtained in pre-op cbk) does not have at least 1 good brick which was up
when the transaction started.

Note: This fix is not related to brick muliplexing. I ran the .t
10 times with this fix and brick-mux enabled without any failures.

Change-Id: I915c9c366aa32cd342b1565827ca2d83cb02ae85
updates: bz#1581548
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
(cherry picked from commit 985a1d15db910e012ddc1dcdc2e333cc28a9968b)

1. If pre-op fails on all bricks,set lock->release to true in
afr_handle_lock_acquire_failure so that the GF_ASSERT in afr_unlock() does not
crash.

2. Added a missing 'return' after handling pre-op failure in
afr_transaction_perform_fop(), fixing a use-after-free issue.

Change-Id: If0627a9124cb5d6405037cab3f17f8325eed2d83
fixes: bz#1561129
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

Problem:
1) Afr's eager-lock only works for data transactions.
2) When there are conflicting writes, write with conflicting region initiates
unlock of eager-lock leading to extra pre-ops and post-ops on the file. When
eager-lock goes off, it leads to extra fsyncs for random-write workload in afr.

Solution (that is modeled after EC):
In EC, when there is a conflicting write, it waits for the current write to
complete before it winds the conflicted write. This leads to better utilization
of network and disk, because we will not be doing extra xattrops and FSYNCs and
inodelk/unlock. Moved fd based counters to inode based counters.

I tried to model the solution based on EC's locking, but it is not similar to
AFR because we had to keep backward compatibility.

Lifecycle of lock:
==================
First transaction is added to inode->owners list and an inodelk will be sent on
the wire. All the next transactions will be put in inode->waiters list until
the first transaction completes inodelk and [f]xattrop completely.  Once
[f]xattrop also completes, all the requests in the inode->waiters list are
checked if it conflict with any of the existing locks which are in
inode->owners list and if not are added to inode->owners list and resumed with
doing transaction. When these transactions complete fop phase they will be
moved to inode->post_op list and resume the transactions that were paused
because of conflicts. Post-op and unlock will not be issued on the wire until
that is the last transaction on that inode. Last transaction when it has to
perform post-op can choose to sleep for deyed-post-op-secs value. During that
time if any other transaction comes, it will wake up the sleeping transaction
and takes over the ownership of the lock and the cycle continues. If the
dealyed-post-op-secs expire, then the timer thread will wakeup the sleeping
transaction and it will set lock->release to true and starts doing post-op and
then unlock. During this time if any other transactions come, they will be put
in inode->frozen list. Once the previous unlock comes it will move the frozen
list to waiters list and moves the first element from this waiters-list to
owners-list and attempts the lock and the cycle continues. This is the general
idea.  There is logic at the time of dealying and at the time of new
transaction or in flush fop to wakeup existing sleeping transactions or
choosing whether to delay a transaction etc, which is subjected to change based
on future enhancements etc.

Fixes: #418
BUG: 1549606
Change-Id: I88b570bbcf332a27c82d2767dfa82472f60055dc
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

Problem:
We currently don't have a roll-back/undoing of post-ops if quorum is not
met. Though the FOP is still unwound with failure, the xattrs remain on
the disk.  Due to these partial post-ops and partial heals (healing only when
2 bricks are up), we can end up in split-brain purely from the afr
xattrs point of view i.e each brick is blamed by atleast one of the
others. These scenarios are hit when there is frequent
connect/disconnect of the client/shd to the bricks while I/O or heal
are in progress.

Fix:
Instead of undoing the post-op, pick a source based on the xattr values.
If 2 bricks blame one, the blamed one must be treated as sink.
If there is no majority, all are sources. Once we pick a source,
self-heal will then do the heal instead of erroring out due to
split-brain.

Change-Id: I3d0224b883eb0945785ade0e9697a1c828aec0ae
BUG: 1539358
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

afr relies on pending changelog xattrs to identify source and sinks and the
setting of these xattrs happen in post-op. So if post-op fails, we need to
unwind the write txn with a failure.

Change-Id: I0f019ac03890108324ee7672883d774918b20be1
BUG: 1506140
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

so that glusterd is also aware that shd is up and running.

While not reproducible locally, on the jenkins slaves, 'gluster vol heal patchy'
fails with "Self-heal daemon is not running. Check self-heal daemon log file.",
while infact the afr_child_up_status_in_shd() checks before that passed. In the
shd log also, I see the shd being up and connected to at least one brick before
the heal is launched.

Change-Id: Id3801fa4ab56a70b1f0bd6a7e240f69bea74a5fc
BUG: 1515163
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

This reverts commit 56e5fdae74845dfec0ff7ad0c8fee77695d36ad5.

Change-Id: Ia62cee5440bbe8e23f5da9cff692d792091d544a
Signed-off-by: Milind Changire <mchangir@redhat.com>

Patch attempts to use the epoll infra for handling SSL connections
as well instead of the socket_poller() thread func.
This essentially makes priv->own_thread flag redundant.

SSL_connect()/SSL_accept() is now non-blocking which has done away
with the localised poll() in ssl_do(). So, ssl_do() has been updated
appropriately.

own_thread and coincidently socket_poller() thread for SSL processing
is now deprecated.

Added a timeout to test whether seal-heal daemon is up and running
as per Ravi's suggestion.

Change-Id: If2b5d7b4fd19e321cb289e08d49a718d2161aafe
Signed-off-by: Milind Changire <mchangir@redhat.com>

Problem:
In an arbiter volume, lookup was being served from one of the sink
bricks (source brick was down). shard uses the iatt values from lookup cbk
to calculate the size and block count, which in this case were incorrect
values. shard_local_t->last_block was thus initialised to -1, resulting
in an infinite while loop in shard_common_resolve_shards().

Fix:
Use client quorum logic to allow or fail the lookups from afr if there
are no readable subvolumes. So in replica-3 or arbiter vols, if there is
no good copy or if quorum is not met, fail lookup with ENOTCONN.

With this fix, we are also removing support for quorum-reads xlator
option. So if quorum is not met, neither read nor write txns are allowed
and we fail the fop with ENOTCONN.

Change-Id: Ic65c00c24f77ece007328b421494eee62a505fa0
BUG: 1467250
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

The restriction of using fds opened by the same Pid means fds cannot
be shared across threads of multithreaded application. Note that fops
from kernel have different Pid for different threads. Imagine
following sequence of operations:

* Turn off performance.open-behind
* Thread t1 opens an fd - fd1 - on file "file". Let's assume nodeid of
  "file" is "nodeid-file".
* Thread t2 does RENAME ("newfile", "file"). Let's assume nodeid of
  "newfile" as "nodeid-newfile".
* t2 proceeds to do fstat (fd1)

The above set of operations can sometimes result in ESTALE/ENOENT
errors. RENAME overwrites "file" with "newfile" changing its nodeid
from "nodeid-file" to "nodeid-newfile" and post RENAME, "nodeid-file" is
removed from the backend. If fstat carries nodeid-file as argument,
which can happen if lookup has not refreshed the nodeid of "file" and
since t2 doesn't have an fd opened, fuse_getattr_resume uses STAT
which will fail as "nodeid-file" no longer exists.

Since the above set of operations and sharing of fds across
multiple threads are valid, this is a bug.

The fix is to use any fd opened on the inode. In this specific example
fuse_getattr_resume will find fd1 and winds down the call as fstat
(fd1) which won't fail.

Cross-checked with "Miklos Szeredi" <mszeredi.at.redhat.dot.com> for
any security issues with this solution and he approves the solution.

Thanks to "Miklos Szeredi" <mszeredi.at.redhat.dot.com> for all the
pointers and discussions.

Change-Id: I88dd29b3607cd2594eee9d72a1637b5346c8d49c
BUG: 1510401
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>