Implement and use cursor routines for bio message data items for
outbound message data.
(See the previous commit for reasoning in support of the changes
in out_msg_pos_next().)
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Switch to using the message cursor for the (non-trail) outgoing
pagelist data item in a message if present.
Notes on the logic changes in out_msg_pos_next():
- only the mds client uses a ceph pagelist for message data;
- if the mds client ever uses a pagelist, it never uses a page
array (or anything else, for that matter) for data in the same
message;
- only the osd client uses the trail portion of a message data,
and when it does, it never uses any other data fields for
outgoing data in the same message; and finally
- only the rbd client uses bio message data (never pagelist).
Therefore out_msg_pos_next() can assume:
- if we're in the trail portion of a message, the message data
pagelist, data, and bio can be ignored; and
- if there is a page list, there will never be any a bio or page
array data, and vice-versa.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This just inserts some infrastructure in preparation for handling
other types of ceph message data items. No functional changes,
just trying to simplify review by separating out some noise.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This patch lays out the foundation for using generic routines to
manage processing items of message data.
For simplicity, we'll start with just the trail portion of a
message, because it stands alone and is only present for outgoing
data.
First some basic concepts. We'll use the term "data item" to
represent one of the ceph_msg_data structures associated with a
message. There are currently four of those, with single-letter
field names p, l, b, and t. A data item is further broken into
"pieces" which always lie in a single page. A data item will
include a "cursor" that will track state as the memory defined by
the item is consumed by sending data from or receiving data into it.
We define three routines to manipulate a data item's cursor: the
"init" routine; the "next" routine; and the "advance" routine. The
"init" routine initializes the cursor so it points at the beginning
of the first piece in the item. The "next" routine returns the
page, page offset, and length (limited by both the page and item
size) of the next unconsumed piece in the item. It also indicates
to the caller whether the piece being returned is the last one in
the data item.
The "advance" routine consumes the requested number of bytes in the
item (advancing the cursor). This is used to record the number of
bytes from the current piece that were actually sent or received by
the network code. It returns an indication of whether the result
means the current piece has been fully consumed. This is used by
the message send code to determine whether it should calculate the
CRC for the next piece processed.
The trail of a message is implemented as a ceph pagelist. The
routines defined for it will be usable for non-trail pagelist data
as well.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Group the types of message data into an abstract structure with a
type indicator and a union containing fields appropriate to the
type of data it represents. Use this to represent the pages,
pagelist, bio, and trail in a ceph message.
Verify message data is of type NONE in ceph_msg_data_set_*()
routines. Since information about message data of type NONE really
should not be interpreted, get rid of the other assertions in those
functions.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
A ceph message has a data payload portion. The memory for that data
(either the source of data to send or the location to place data
that is received) is specified in several ways. The ceph_msg
structure includes fields for all of those ways, but this
mispresents the fact that not all of them are used at a time.
Specifically, the data in a message can be in:
- an array of pages
- a list of pages
- a list of Linux bios
- a second list of pages (the "trail")
(The two page lists are currently only ever used for outgoing data.)
Impose more structure on the ceph message, making the grouping of
some of these fields explicit. Shorten the name of the
"page_alignment" field.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define and use macros ceph_msg_has_*() to determine whether to
operate on the pages, pagelist, bio, and trail fields of a message.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Factor out a common block of code that updates a CRC calculation
over a range of data in a page.
This and the preceding patches are related to:
http://tracker.ceph.com/issues/4403
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define a new function ceph_tcp_recvpage() that behaves in a way
comparable to ceph_tcp_sendpage().
Rearrange the code in both read_partial_message_pages() and
read_partial_message_bio() so they have matching structure,
(similar to what's in write_partial_msg_pages()), and use
this new function.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Pull the code that reads the data portion into a message into
a separate function read_partial_msg_data().
Rename write_partial_msg_pages() to be write_partial_message_data()
to match its read counterpart, and to reflect its more generic
purpose.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define local variables page_offset and length to represent the range
of bytes within a page that will be sent by ceph_tcp_sendpage() in
write_partial_msg_pages().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
In prepare_write_message_data(), various fields are initialized in
preparation for writing message data out. Meanwhile, in
read_partial_message(), there is essentially the same block of code,
operating on message variables associated with an incoming message.
Generalize prepare_write_message_data() so it works for both
incoming and outcoming messages, and use it in both spots. The
did_page_crc is not used for input (so it's harmless to initialize
it).
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
There are several places where a message's out_msg_pos or in_msg_pos
field is used repeatedly within a function. Use a local pointer
variable for this purpose to unclutter the code.
This and the upcoming cleanup patches are related to:
http://tracker.ceph.com/issues/4403
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
At one time it was necessary to clear a message's bio_iter field to
avoid a bad pointer dereference in write_partial_msg_pages().
That no longer seems to be the case. Here's why.
The message's bio fields represent (in this case) outgoing data.
Between where the bio_iter is made NULL in prepare_write_message()
and the call in that function to prepare_message_data(), the
bio fields are never used.
In prepare_message_data(), init-bio_iter() is called, and the result
of that overwrites the value in the message's bio_iter field.
Because it gets overwritten anyway, there is no need to set it to
NULL. So don't do it.
This resolves:
http://tracker.ceph.com/issues/4402
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
The mds client no longer tries to assign zero-length message data,
and the osd client no longer sets its data info more than once.
This allows us to activate assertions in the messenger to verify
these things never happen.
This resolves both of these:
http://tracker.ceph.com/issues/4263http://tracker.ceph.com/issues/4284
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
Record the number of bytes of data in a page array rather than the
number of pages in the array. It can be assumed that the page array
is of sufficient size to hold the number of bytes indicated (and
offset by the indicated alignment).
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Change it so we only assign outgoing data information for messages
if there is outgoing data to send.
This then allows us to add a few more (currently commented-out)
assertions.
This is related to:
http://tracker.ceph.com/issues/4284
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
Define ceph_msg_data_set_pagelist(), ceph_msg_data_set_bio(), and
ceph_msg_data_set_trail() to clearly abstract the assignment of the
remaining data-related fields in a ceph message structure. Use the
new functions in the osd client and mds client.
This partially resolves:
http://tracker.ceph.com/issues/4263
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
When setting page array information for message data, provide the
byte length rather than the page count ceph_msg_data_set_pages().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define a function ceph_msg_data_set_pages(), which more clearly
abstracts the assignment page-related fields for data in a ceph
message structure. Use this new function in the osd client and mds
client.
Ideally, these fields would never be set more than once (with
BUG_ON() calls to guarantee that). At the moment though the osd
client sets these every time it receives a message, and in the event
of a communication problem this can happen more than once. (This
will be resolved shortly, but setting up these helpers first makes
it all a bit easier to work with.)
Rearrange the field order in a ceph_msg structure to group those
that are used to define the possible data payloads.
This partially resolves:
http://tracker.ceph.com/issues/4263
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Rather than explicitly initializing many fields to 0, NULL, or false
in a newly-allocated message, just use kzalloc() for allocating new
messages. This will become a much more convenient way of doing
things anyway for upcoming patches that abstract the data field.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
While processing an outgoing pagelist (either the data pagelist or
trail) in a ceph message, the messenger cycles through each of the
pages on the list. This is accomplished in out_msg_pos_next(), if
the end of the first page on the list is reached, the first page is
moved to the end of the list.
There is a list operation, list_rotate_left(), which performs
exactly this operation, and by using it, what's really going on
becomes more obvious.
So replace these two list_move_tail() calls with list_rotate_left().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define a new function in_msg_pos_next() to match out_msg_pos_next(),
and use it in place of code at the end of read_partial_message_pages()
and read_partial_message_bio().
Note that the page number is incremented and offset reset under
slightly different conditions from before. The result is
equivalent, however, as explained below.
Each time an incoming message is going to arrive, we find out how
much room is left--not surpassing the current page--and provide that
as the number of bytes to receive. So the amount we'll use is the
lesser of: all that's left of the entire request; and all that's
left in the current page.
If we received exactly how many were requested, we either reached
the end of the request or the end of the page. In the first case,
we're done, in the second, we move onto the next page in the array.
In all cases but (possibly) on the last page, after adding the
number of bytes received, page_pos == PAGE_SIZE. On the last page,
it doesn't really matter whether we increment the page number and
reset the page position, because we're done and we won't come back
here again. The code previously skipped over that last case,
basically. The new code handles that case the same as the others,
incrementing and resetting.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
There is only one caller for read_partial_message_bio(), and it
always passes &msg->bio_iter and &bio_seg as the second and third
arguments. Furthermore, the message in question is always the
connection's in_msg, and we can get that inside the called function.
So drop those two parameters and use their derived equivalents.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Change the type of the "more" parameter from int to bool.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Some values printed are not (necessarily) in CPU order. We already
have a copy of the converted versions, so use them.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This is probably unnecessary but the code read as if it were wrong
in read_partial_message().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
In ceph_con_in_msg_alloc() it is possible for a connection's
alloc_msg method to indicate an incoming message should be skipped.
By default, read_partial_message() initializes the skip variable
to 0 before it gets provided to ceph_con_in_msg_alloc().
The osd client, mon client, and mds client each supply an alloc_msg
method. The mds client always assigns skip to be 0.
The other two leave the skip value of as-is, or assigns it to zero,
except:
- if no (osd or mon) request having the given tid is found, in
which case skip is set to 1 and NULL is returned; or
- in the osd client, if the data of the reply message is not
adequate to hold the message to be read, it assigns skip
value 1 and returns NULL.
So the returned message pointer will always be NULL if skip is ever
non-zero.
Clean up the logic a bit in ceph_con_in_msg_alloc() to make this
state of affairs more obvious. Add a comment explaining how a null
message pointer can mean either a message that should be skipped or
a problem allocating a message.
This resolves:
http://tracker.ceph.com/issues/4324
Reported-by: Greg Farnum <greg@inktank.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
The only user of the ceph messenger that doesn't define an alloc_msg
method is the mds client. Define one, such that it works just like
it did before, and simplify ceph_con_in_msg_alloc() by assuming the
alloc_msg method is always present.
This and the next patch resolve:
http://tracker.ceph.com/issues/4322
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
In ceph_con_in_msg_alloc(), if no alloc_msg method is defined for a
connection a new message is allocated with ceph_msg_new().
Drop the mutex before making this call, and make sure we're still
connected when we get it back again.
This is preparing for the next patch, which ensures all connections
define an alloc_msg method, and then handles them all the same way.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
The pagelist_count field is never actually used, so get rid of it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Use distinct fields for tracking the number of pages in a message's
page array and in a message's page list. Currently only one or the
other is used at a time, but that will be changing soon.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
The bio_seg field is used by the ceph messenger in iterating through
a bio. It should never have a negative value, so make it an
unsigned. (I contemplated making it unsigned short to match the
struct bio definition, but it offered no benefit.)
Change variables used to hold bio_seg values to all be unsigned as
well. Change two variable names in init_bio_iter() to match the
convention used everywhere else.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This just converts a manually-implemented loop into a do..while loop
in con_work(). It also moves handling of EAGAIN inside the blocks
where it's already been determined an error code was returned.
Also update a few dout() calls near the affected code for
consistency.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This just rearranges the logic in con_work() a little bit so that a
flag is used to indicate a fault has occurred. This allows both the
fault and non-fault case to be handled the same way and avoids a
couple of nearly consecutive gotos.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
An error occurring on a ceph connection is treated as a fault,
causing the connection to be reset. The initial part of this fault
handling has to be done while holding the connection mutex, but
it must then be dropped for the last part.
Separate the part of this fault handling that executes without the
lock into its own function, con_fault_finish(). Move the call to
this new function, as well as call that drops the connection mutex,
into ceph_fault(). Rename that function con_fault() to reflect that
it's only handling the connection part of the fault handling.
The motivation for this was a warning from sparse about the locking
being done here. Rearranging things this way keeps all the mutex
manipulation within ceph_fault(), and this stops sparse from
complaining.
This partially resolves:
http://tracker.ceph.com/issues/4184
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Collect the code that tests for and implements a backoff delay for a
ceph connection into a new function, ceph_backoff().
Make the debug output messages in that part of the code report
things consistently by reporting a message in the socket closed
case, and by making the one for PREOPEN state report the connection
pointer like the rest.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Eliminate most of the problems in the libceph code that cause sparse
to issue warnings.
- Convert functions that are never referenced externally to have
static scope.
- Pass NULL rather than 0 for a pointer argument in one spot in
ceph_monc_delete_snapid()
This partially resolves:
http://tracker.ceph.com/issues/4184
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Define and use functions that encapsulate operations performed on
a connection's flags.
This resolves:
http://tracker.ceph.com/issues/4234
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
The ceph messenger has a few spots that are only used when
bio messages are supported, and that's only when CONFIG_BLOCK
is defined. This surrounds a couple of spots with #ifdef's
that would cause a problem if CONFIG_BLOCK were not present
in the kernel configuration.
This resolves:
http://tracker.ceph.com/issues/3976
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
We should not set con->state to CLOSED here; that happens in
ceph_fault() in the caller, where it first asserts that the state
is not yet CLOSED. Avoids a BUG when the features don't match.
Since the fail_protocol() has become a trivial wrapper, replace
calls to it with direct calls to reset_connection().
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
A number of assertions in the ceph messenger are implemented with
BUG_ON(), killing the system if connection's state doesn't match
what's expected. At this point our state model is (evidently) not
well understood enough for these assertions to trigger a BUG().
Convert all BUG_ON(con->state...) calls to be WARN_ON(con->state...)
so we learn about these issues without killing the machine.
We now recognize that a connection fault can occur due to a socket
closure at any time, regardless of the state of the connection. So
there is really nothing we can assert about the state of the
connection at that point so eliminate that assertion.
Reported-by: Ugis <ugis22@gmail.com>
Tested-by: Ugis <ugis22@gmail.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
When a connection's socket disconnects, or if there's a protocol
error of some kind on the connection, a fault is signaled and
the connection is reset (closed and reopened, basically). We
currently get an error message on the log whenever this occurs.
A ceph connection will attempt to reestablish a socket connection
repeatedly if a fault occurs. This means that these error messages
will get repeatedly added to the log, which is undesirable.
Change the error message to be a warning, so they don't get
logged by default.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
A connection's socket can close for any reason, independent of the
state of the connection (and without irrespective of the connection
mutex). As a result, the connectino can be in pretty much any state
at the time its socket is closed.
Handle those other cases at the top of con_work(). Pull this whole
block of code into a separate function to reduce the clutter.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
The ceph_on_in_msg_alloc() method calls the ->alloc_msg() helper which
may return NULL. It also drops con->mutex while it allocates a message,
which means that the connection state may change (e.g., get closed). If
that happens, we clean up and bail out. Avoid calling ceph_msg_put() on
a NULL return value and triggering a crash.
This was observed when an ->alloc_msg() call races with a timeout that
resends a zillion messages and resets the connection, and ->alloc_msg()
returns NULL (because the request was resent to another target).
Fixes http://tracker.newdream.net/issues/3342
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This patch defines a single function, queue_con_delay() to call
queue_delayed_work() for a connection. It basically generalizes
what was previously queue_con() by adding the delay argument.
queue_con() is now a simple helper that passes 0 for its delay.
queue_con_delay() returns 0 if it queued work or an errno if it
did not for some reason.
If con_work() finds the BACKOFF flag set for a connection, it now
calls queue_con_delay() to handle arranging to start again after a
delay.
Note about connection reference counts: con_work() only ever gets
called as a work item function. At the time that work is scheduled,
a reference to the connection is acquired, and the corresponding
con_work() call is then responsible for dropping that reference
before it returns.
Previously, the backoff handling inside con_work() silently handed
off its reference to delayed work it scheduled. Now that
queue_con_delay() is used, a new reference is acquired for the
newly-scheduled work, and the original reference is dropped by the
con->ops->put() call at the end of the function.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Both ceph_fault() and con_work() include handling for imposing a
delay before doing further processing on a faulted connection.
The latter is used only if ceph_fault() is unable to.
Instead, just let con_work() always be responsible for implementing
the delay. After setting up the delay value, set the BACKOFF flag
on the connection unconditionally and call queue_con() to ensure
con_work() will get called to handle it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
If ceph_fault() is unable to queue work after a delay, it sets the
BACKOFF connection flag so con_work() will attempt to do so.
In con_work(), when BACKOFF is set, if queue_delayed_work() doesn't
result in newly-queued work, it simply ignores this condition and
proceeds as if no backoff delay were desired. There are two
problems with this--one of which is a bug.
The first problem is simply that the intended behavior is to back
off, and if we aren't able queue the work item to run after a delay
we're not doing that.
The only reason queue_delayed_work() won't queue work is if the
provided work item is already queued. In the messenger, this
means that con_work() is already scheduled to be run again. So
if we simply set the BACKOFF flag again when this occurs, we know
the next con_work() call will again attempt to hold off activity
on the connection until after the delay.
The second problem--the bug--is a leak of a reference count. If
queue_delayed_work() returns 0 in con_work(), con->ops->put() drops
the connection reference held on entry to con_work(). However,
processing is (was) allowed to continue, and at the end of the
function a second con->ops->put() is called.
This patch fixes both problems.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
In write_partial_msg_pages(), pages need to be kmapped in order to
perform a CRC-32c calculation on them. As an artifact of the way
this code used to be structured, the kunmap() call was separated
from the kmap() call and both were done conditionally. But the
conditions under which the kmap() and kunmap() calls were made
differed, so there was a chance a kunmap() call would be done on a
page that had not been mapped.
The symptom of this was tripping a BUG() in kunmap_high() when
pkmap_count[nr] became 0.
Reported-by: Bryan K. Wright <bryan@virginia.edu>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Because the Ceph client messenger uses a non-blocking connect, it is
possible for the sending of the client banner to race with the
arrival of the banner sent by the peer.
When ceph_sock_state_change() notices the connect has completed, it
schedules work to process the socket via con_work(). During this
time the peer is writing its banner, and arrival of the peer banner
races with con_work().
If con_work() calls try_read() before the peer banner arrives, there
is nothing for it to do, after which con_work() calls try_write() to
send the client's banner. In this case Ceph's protocol negotiation
can complete succesfully.
The server-side messenger immediately sends its banner and addresses
after accepting a connect request, *before* actually attempting to
read or verify the banner from the client. As a result, it is
possible for the banner from the server to arrive before con_work()
calls try_read(). If that happens, try_read() will read the banner
and prepare protocol negotiation info via prepare_write_connect().
prepare_write_connect() calls con_out_kvec_reset(), which discards
the as-yet-unsent client banner. Next, con_work() calls
try_write(), which sends the protocol negotiation info rather than
the banner that the peer is expecting.
The result is that the peer sees an invalid banner, and the client
reports "negotiation failed".
Fix this by moving con_out_kvec_reset() out of
prepare_write_connect() to its callers at all locations except the
one where the banner might still need to be sent.
[elder@inktak.com: added note about server-side behavior]
Signed-off-by: Jim Schutt <jaschut@sandia.gov>
Reviewed-by: Alex Elder <elder@inktank.com>
