The ceph_fault() function takes the con mutex, so we should avoid
dropping it before calling it.  This fixes a potential race with
another thread calling ceph_con_close(), or _open(), or similar (we
don't reverify con->state after retaking the lock).

Add annotation so that lockdep realizes we will drop the mutex before
returning.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

We drop the con mutex when delivering a message.  When we retake the
lock, we need to verify we are still in the OPEN state before
preparing to read the next tag, or else we risk stepping on a
connection that has been closed.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

If the connect() call immediately fails such that sock == NULL, we
still need con_close_socket() to reset our socket state to CLOSED.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

Signed-off-by: NSage Weil <sage@inktank.com>

Rename flags with CON_FLAG prefix, move the definitions into the c file,
and (better) document their meaning.
Signed-off-by: NSage Weil <sage@inktank.com>

Use a simple set of 6 enumerated values for the socket states (CON_STATE_*)
and use those instead of the state bits.  All of the con->state checks are
now under the protection of the con mutex, so this is safe.  It also
simplifies many of the state checks because we can check for anything other
than the expected state instead of various bits for races we can think of.

This appears to hold up well to stress testing both with and without socket
failure injection on the server side.
Signed-off-by: NSage Weil <sage@inktank.com>

If we are CLOSED, the socket is closed and we won't get these.
Signed-off-by: NSage Weil <sage@inktank.com>

It is simpler to do this immediately, since we already hold the con mutex.
It also avoids the need to deal with a not-quite-CLOSED socket in con_work.
Signed-off-by: NSage Weil <sage@inktank.com>

If the state is CLOSED or OPENING, we shouldn't have a socket.
Signed-off-by: NSage Weil <sage@inktank.com>

Take the con mutex before checking whether the connection is closed to
avoid racing with someone else closing it.
Signed-off-by: NSage Weil <sage@inktank.com>

Avoid dropping and retaking con->mutex in the ceph_con_send() case by
leaving locking up to the caller.
Signed-off-by: NSage Weil <sage@inktank.com>

If we fault on a lossy connection, we should still close the socket
immediately, and do so under the con mutex.

We should also take the con mutex before printing out the state bits in
the debug output.
Signed-off-by: NSage Weil <sage@inktank.com>

We exponentially back off when we encounter connection errors.  If several
errors accumulate, we will eventually wait ages before even trying to
reconnect.

Fix this by resetting the backoff counter after a successful negotiation/
connection with the remote node.  Fixes ceph issue #2802.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NYehuda Sadeh <yehuda@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

Take the con mutex while we are initiating a ceph open.  This is necessary
because the may have previously been in use and then closed, which could
result in a racing workqueue running con_work().
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NYehuda Sadeh <yehuda@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

Previously, we were opportunistically initializing the bio_iter if it
appeared to be uninitialized in the middle of the read path.  The problem
is that a sequence like:

 - start reading message
 - initialize bio_iter
 - read half a message
 - messenger fault, reconnect
 - restart reading message
 - ** bio_iter now non-NULL, not reinitialized **
 - read past end of bio, crash

Instead, initialize the bio_iter unconditionally when we allocate/claim
the message for read.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NYehuda Sadeh <yehuda@inktank.com>

Hold the mutex while twiddling all of the state bits to avoid possible
races.  While we're here, make not of why we cannot close the socket
directly.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NYehuda Sadeh <yehuda@inktank.com>

We need to set error_msg to something useful before calling ceph_fault();
do so here for try_{read,write}().  This is more informative than

libceph: osd0 192.168.106.220:6801 (null)
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NYehuda Sadeh <yehuda@inktank.com>

Add an atomic variable 'stopping' as flag in struct ceph_messenger,
set this flag to 1 in function ceph_destroy_client(), and add the condition code
in function ceph_data_ready() to test the flag value, if true(1), just return.
Signed-off-by: NGuanjun He <gjhe@suse.com>
Reviewed-by: NSage Weil <sage@inktank.com>

In ancient times, the messenger could both initiate and accept connections.
An artifact if that was data structures to store/process an incoming
ceph_msg_connect request and send an outgoing ceph_msg_connect_reply.
Sadly, the negotiation code was referencing those structures and ignoring
important information (like the peer's connect_seq) from the correct ones.

Among other things, this fixes tight reconnect loops where the server sends
RETRY_SESSION and we (the client) retries with the same connect_seq as last
time.  This bug pretty easily triggered by injecting socket failures on the
MDS and running some fs workload like workunits/direct_io/test_sync_io.
Signed-off-by: NSage Weil <sage@inktank.com>

It is possible to close a socket that is in the OPENING state.  For
example, it can happen if ceph_con_close() is called on the con before
the TCP connection is established.  con_work() will come around and shut
down the socket.
Signed-off-by: NSage Weil <sage@inktank.com>

The peer name may change on each open attempt, even when the connection is
reused.
Signed-off-by: NSage Weil <sage@inktank.com>

Sage liked the state diagram I put in my commit description so
I'm putting it in with the code.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

This patch gathers a few small changes in "net/ceph/messenger.c":
  out_msg_pos_next()
    - small logic change that mostly affects indentation
  write_partial_msg_pages().
    - use a local variable trail_off to represent the offset into
      a message of the trail portion of the data (if present)
    - once we are in the trail portion we will always be there, so we
      don't always need to check against our data position
    - avoid computing len twice after we've reached the trail
    - get rid of the variable tmpcrc, which is not needed
    - trail_off and trail_len never change so mark them const
    - update some comments
  read_partial_message_bio()
    - bio_iovec_idx() will never return an error, so don't bother
      checking for it
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Currently a ceph connection enters a "CONNECTING" state when it
begins the process of (re-)connecting with its peer.  Once the two
ends have successfully exchanged their banner and addresses, an
additional NEGOTIATING bit is set in the ceph connection's state to
indicate the connection information exhange has begun.  The
CONNECTING bit/state continues to be set during this phase.

Rather than have the CONNECTING state continue while the NEGOTIATING
bit is set, interpret these two phases as distinct states.  In other
words, when NEGOTIATING is set, clear CONNECTING.  That way only
one of them will be active at a time.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

There are two phases in the process of linking together the two ends
of a ceph connection.  The first involves exchanging a banner and
IP addresses, and if that is successful a second phase exchanges
some detail about each side's connection capabilities.

When initiating a connection, the client side now queues to send
its information for both phases of this process at the same time.
This is probably a bit more efficient, but it is slightly messier
from a layering perspective in the code.

So rearrange things so that the client doesn't send the connection
information until it has received and processed the response in the
initial banner phase (in process_banner()).

Move the code (in the (con->sock == NULL) case in try_write()) that
prepares for writing the connection information, delaying doing that
until the banner exchange has completed.  Move the code that begins
the transition to this second "NEGOTIATING" phase out of
process_banner() and into its caller, so preparing to write the
connection information and preparing to read the response are
adjacent to each other.

Finally, preparing to write the connection information now requires
the output kvec to be reset in all cases, so move that into the
prepare_write_connect() and delete it from all callers.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

There is no state explicitly defined when a ceph connection is fully
operational.  So define one.

It's set when the connection sequence completes successfully, and is
cleared when the connection gets closed.

Be a little more careful when examining the old state when a socket
disconnect event is reported.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

A connection state's NEGOTIATING bit gets set while in CONNECTING
state after we have successfully exchanged a ceph banner and IP
addresses with the connection's peer (the server).  But that bit
is not cleared again--at least not until another connection attempt
is initiated.

Instead, clear it as soon as the connection is fully established.
Also, clear it when a socket connection gets prematurely closed
in the midst of establishing a ceph connection (in case we had
reached the point where it was set).
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

A connection that is closed will no longer be connecting.  So
clear the CONNECTING state bit in ceph_con_close().  Similarly,
if the socket has been closed we no longer are in connecting
state (a new connect sequence will need to be initiated).
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

In con_close_socket(), a connection's SOCK_CLOSED flag gets set and
then cleared while its shutdown method is called and its reference
gets dropped.

Previously, that flag got set only if it had not already been set,
so setting it in con_close_socket() might have prevented additional
processing being done on a socket being shut down.  We no longer set
SOCK_CLOSED in the socket event routine conditionally, so setting
that bit here no longer provides whatever benefit it might have
provided before.

A race condition could still leave the SOCK_CLOSED bit set even
after we've issued the call to con_close_socket(), so we still clear
that bit after shutting the socket down.  Add a comment explaining
the reason for this.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

When a TCP_CLOSE or TCP_CLOSE_WAIT event occurs, the SOCK_CLOSED
connection flag bit is set, and if it had not been previously set
queue_con() is called to ensure con_work() will get a chance to
handle the changed state.

con_work() atomically checks--and if set, clears--the SOCK_CLOSED
bit if it was set.  This means that even if the bit were set
repeatedly, the related processing in con_work() only gets called
once per transition of the bit from 0 to 1.

What's important then is that we ensure con_work() gets called *at
least* once when a socket close event occurs, not that it gets
called *exactly* once.

The work queue mechanism already takes care of queueing work
only if it is not already queued, so there's no need for us
to call queue_con() conditionally.

So this patch just makes it so the SOCK_CLOSED flag gets set
unconditionally in ceph_sock_state_change().
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Currently the socket state change event handler records an error
message on a connection to distinguish a close while connecting from
a close while a connection was already established.

Changing connection information during handling of a socket event is
not very clean, so instead move this assignment inside con_work(),
where it can be done during normal connection-level processing (and
under protection of the connection mutex as well).

Move the handling of a socket closed event up to the top of the
processing loop in con_work(); there's no point in handling backoff
etc. if we have a newly-closed socket to take care of.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

The following commit changed it so SOCK_CLOSED bit was stored in
a connection's new "flags" field rather than its "state" field.

    libceph: start separating connection flags from state
    commit 928443cd

That bit is used in con_close_socket() to protect against setting an
error message more than once in the socket event handler function.

Unfortunately, the field being operated on in that function was not
updated to be "flags" as it should have been.  This fixes that
error.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Recently a bug was fixed in which the bio_iter field in a ceph
message was not being properly re-initialized when a message got
re-transmitted:
    commit 43643528
    Author: Yan, Zheng <zheng.z.yan@intel.com>
    rbd: Clear ceph_msg->bio_iter for retransmitted message

We are now only initializing the bio_iter field when we are about to
start to write message data (in prepare_write_message_data()),
rather than every time we are attempting to write any portion of the
message data (in write_partial_msg_pages()).  This means we no
longer need to use the msg->bio_iter field as a flag.

So just don't do that any more.  Trust prepare_write_message_data()
to ensure msg->bio_iter is properly initialized, every time we are
about to begin writing (or re-writing) a message's bio data.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

If a message has a non-null bio pointer, its bio_iter field is
initialized in write_partial_msg_pages() if this has not been done
already.  This is really a one-time setup operation for sending a
message's (bio) data, so move that initialization code into
prepare_write_message_data() which serves that purpose.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Move init_bio_iter() and iter_bio_next() up in their source file so
the'll be defined before they're needed.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

This is a nit, but prepare_write_message() sets the FOOTER_COMPLETE
flag before the CRC for the data portion (recorded in the footer)
has been completely computed.  Hold off setting the complete flag
until we've decided it's ready to send.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

In write_partial_msg_pages(), once all the data from a page has been
sent we advance to the next one.  Put the code that takes care of
this into its own function.

While modifying write_partial_msg_pages(), make its local variable
"in_trail" be Boolean, and use the local variable "msg" (which is
just the connection's current out_msg pointer) consistently.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Move the code that prepares to write the data portion of a message
into its own function.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

These are no longer used.  Every ceph_connection instance is embedded in
another structure, and refcounts manipulated via the get/put ops.
Signed-off-by: NSage Weil <sage@inktank.com>

The ceph_con_get/put() helpers manipulate the embedded con ref
count, which isn't used now that ceph_connections are embedded in
other structures.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>