Add support for CEPH_OSD_OP_STAT operations in the osd client
and in rbd.

This operation sends no data to the osd; everything required is
encoded in identity of the target object.

The result will be ENOENT if the object doesn't exist.  If it does
exist and no other error occurs the server returns the size and last
modification time of the target object as output data (in little
endian format).  The size is a 64 bit unsigned and the time is
ceph_timespec structure (two unsigned 32-bit integers, representing
a seconds and nanoseconds value).

This resolves:
    http://tracker.ceph.com/issues/4007Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The for_each_obj_request*() macros should parenthesize their uses of
the ireq parameter.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

There is only one caller of ceph_osdc_create_event(), and it
provides 0 as its "one_shot" argument.  Get rid of that argument and
just use 0 in its place.

Replace the code in handle_watch_notify() that executes if one_shot
is nonzero in the event with a BUG_ON() call.

While modifying "osd_client.c", give handle_watch_notify() static
scope.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Somehow, I missed this little item in Documentation/atomic_ops.txt:
    *** WARNING: atomic_read() and atomic_set() DO NOT IMPLY BARRIERS! ***

Create and use some helper functions that include the proper memory
barriers for manipulating the done field.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

This commit:
    bc7a62ee5 rbd: prevent open for image being removed
added checking for removing rbd before allowing an open, and used
the same request spinlock for protecting that and updating the open
count as is used for the request queue.

However it used the non-irq protected version of the spinlocks.
Fix that.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

There is a check in the completion path for osd requests that
ensures the number of pages allocated is enough to hold the amount
of incoming data expected.

For bio requests coming from rbd the "number of pages" is not really
meaningful (although total length would be).  So stop requiring that
nr_pages be supplied for bio requests.  This is done by checking
whether the pages pointer is null before checking the value of
nr_pages.

Note that this value is passed on to the messenger, but there it's
only used for debugging--it's never used for validation.

While here, change another spot that used r_pages in a debug message
inappropriately, and also invalidate the r_con_filling_msg pointer
after dropping a reference to it.

This resolves:
    http://tracker.ceph.com/issues/3875Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Currently, if the OSD client finds an osd request has had a bio list
attached to it, it drops a reference to it (or rather, to the first
entry on that list) when the request is released.

The code that added that reference (i.e., the rbd client) is
therefore required to take an extra reference to that first bio
structure.

The osd client doesn't really do anything with the bio pointer other
than transfer it from the osd request structure to outgoing (for
writes) and ingoing (for reads) messages.  So it really isn't the
right place to be taking or dropping references.

Furthermore, the rbd client already holds references to all bio
structures it passes to the osd client, and holds them until the
request is completed.  So there's no need for this extra reference
whatsoever.

So remove the bio_put() call in ceph_osdc_release_request(), as
well as its matching bio_get() call in rbd_osd_req_create().

This change could lead to a crash if old libceph.ko was used with
new rbd.ko.  Add a compatibility check at rbd initialization time to
avoid this possibilty.

This resolves:
    http://tracker.ceph.com/issues/3798    and
    http://tracker.ceph.com/issues/3799Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An open request for a mapped rbd image can arrive while removal of
that mapping is underway.  We need to prevent such an open request
from succeeding.  (It appears that Maciej Galkiewicz ran into this
problem.)

Define and use a "removing" flag to indicate a mapping is getting
removed.  Set it in the remove path after verifying nothing holds
the device open.  And check it in the open path before allowing the
open to proceed.  Acquire the rbd device's lock around each of these
spots to avoid any races accessing the flags and open_count fields.

This addresses:
    http://tracker.newdream.net/issues/3427Reported-by: NMaciej Galkiewicz <maciejgalkiewicz@ragnarson.com>
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Define a new rbd device flags field, manipulated using bit
operations.  Replace the use of the current "exists" flag with a bit
in this new "flags" field.  Add a little commentary about the
"exists" flag, which does not need to be manipulated atomically.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When we register an osd request to linger, it means that request
will stay around (under control of the osd client) until we've
unregistered it.  We do that for an rbd image's header object, and
we keep a pointer to the object request associated with it.

Keep a reference to the watch object request for as long as it is
registered to linger.  Drop it again after we've removed the linger
registration.

This resolves:
    http://tracker.ceph.com/issues/3937

(Note: this originally came about because the osd client was
issuing a callback more than once.  But that behavior will be
changing soon, documented in tracker issue 3967.)
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Decrement the obj_request_count value when deleting an object
request from its image request's list.  Rearrange a few lines
in the surrounding code.

This resolves:
    http://tracker.ceph.com/issues/3940Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Switch to keeping track of the object request pointer rather than
the osd request used to watch the rbd image header object.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Move the code that unregisters an rbd device's lingering header
object watch request into rbd_dev_header_watch_sync(), so it
occurs in the same function that originally sets up that request.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Get rid rbd_req_sync_exec() because it is no longer used.  That
eliminates the last use of rbd_req_sync_op(), so get rid of that
too.  And finally, that leaves rbd_do_request() unreferenced, so get
rid of that.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Reimplement synchronous object method calls using the new request
tracking code.  Use the name rbd_obj_method_sync()
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When we receive notification of a change to an rbd image's header
object we need to refresh our information about the image (its
size and snapshot context).  Once we have refreshed our rbd image
we need to acknowledge the notification.

This acknowledgement was previously done synchronously, but there's
really no need to wait for it to complete.

Change it so the caller doesn't wait for the notify acknowledgement
request to complete.  And change the name to reflect it's no longer
synchronous.

This resolves:
    http://tracker.newdream.net/issues/3877Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Get rid rbd_req_sync_notify_ack() because it is no longer used.
As a result rbd_simple_req_cb() becomes unreferenced, so get rid
of that too.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Use the new object request tracking mechanism for handling a
notify_ack request.

Move the callback function below the definition of this so we don't
have to do a pre-declaration.

This resolves:
    http://tracker.newdream.net/issues/3754Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Get rid of rbd_req_sync_watch(), because it is no longer used.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Implement a new function to set up or tear down a watch event
for an mapped rbd image header using the new request code.

Create a new object request type "nodata" to handle this.  And
define rbd_osd_trivial_callback() which simply marks a request done.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Delete rbd_req_sync_read() is no longer used, so get rid of it.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Reimplement the synchronous read operation used for reading a
version 1 header using the new request tracking code.  Name the
resulting function rbd_obj_read_sync() to better reflect that
it's a full object operation, not an object request.  To do this,
implement a new OBJ_REQUEST_PAGES object request type.

This implements a new mechanism to allow the caller to wait for
completion for an rbd_obj_request by calling rbd_obj_request_wait().

This partially resolves:
    http://tracker.newdream.net/issues/3755Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The two remaining callers of rbd_do_request() always pass a null
collection pointer, so the "coll" and "coll_index" parameters are
not needed.  There is no other use of that data structure, so it
can be eliminated.

Deleting them means there is no need to allocate a rbd_request
structure for the callback function.  And since that's the only use
of *that* structure, it too can be eliminated.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Now that the request function has been replaced by one using the new
request management data structures the old one can go away.
Deleting it makes rbd_dev_do_request() no longer needed, and
deleting that makes other functions unneeded, and so on.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

This patch fully implements the new request tracking code for rbd
I/O requests.

Each I/O request to an rbd image will get an rbd_image_request
structure allocated to track it.  This provides access to all
information about the original request, as well as access to the
set of one or more object requests that are initiated as a result
of the image request.

An rbd_obj_request structure defines a request sent to a single osd
object (possibly) as part of an rbd image request.  An rbd object
request refers to a ceph_osd_request structure built up to represent
the request; for now it will contain a single osd operation.  It
also provides space to hold the result status and the version of the
object when the osd request completes.

An rbd_obj_request structure can also stand on its own.  This will
be used for reading the version 1 header object, for issuing
acknowledgements to event notifications, and for making object
method calls.

All rbd object requests now complete asynchronously with respect
to the osd client--they supply a common callback routine.

This resolves:
    http://tracker.newdream.net/issues/3741Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When an rbd image is initially mapped a watch event is registered so
we can do something if the header object changes.

The code that does this currently loops if initiating the watch
request results in an ERANGE error.  The osds will never return
ERANGE, so there's no reason to do this loop, so get rid of it.

This resolves:
    http://tracker.newdream.net/issues/3860

Note that the problem this loop was intended to solve is a race
between collecting image header information and setting up the watch
on the header object.  The real fix for that problem is described
here:
    http://tracker.newdream.net/issues/3871Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The return type of rbd_get_num_segments() is int, but the values it
operates on are u64.  Although it's not likely, there's no guarantee
the result won't exceed what can be respresented in an int.  The
function is already designed to return -ERANGE on error, so just add
this possible overflow as another reason to return that.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NDan Mick <dan.mick@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

A few very minor changes to the rbd code:
    - RBD_MAX_OPT_LEN is unused, so get rid of it
    - Consolidate rbd options definitions
    - Make rbd_segment_name() return pointer to const char
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NDan Mick <dan.mick@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The type of the snap_id local variable is defined with the
wrong byte order.  Fix that.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Both rbd_req_sync_op() and rbd_do_request() have a "linger"
parameter, which is the address of a pointer that should refer to
the osd request structure used to issue a request to an osd.

Only one case ever supplies a non-null "linger" argument: an
CEPH_OSD_OP_WATCH start.  And in that one case it is assigned
&rbd_dev->watch_request.

Within rbd_do_request() (where the assignment ultimately gets made)
we know the rbd_dev and therefore its watch_request field.  We
also know whether the op being sent is CEPH_OSD_OP_WATCH start.

Stop opaquely passing down the "linger" pointer, and instead just
assign the value directly inside rbd_do_request() when it's needed.

This makes it unnecessary for rbd_req_sync_watch() to make
arrangements to hold a value that's not available until a
bit later.  This more clearly separates setting up a watch
request from submitting it.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The two remaining osd ops used by rbd are CEPH_OSD_OP_WATCH and
CEPH_OSD_OP_NOTIFY_ACK.  Move the setup of those operations into
rbd_osd_req_op_create(), and get rid of rbd_create_rw_op() and
rbd_destroy_op().
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Move the initialization of the CEPH_OSD_OP_CALL operation into
rbd_osd_req_op_create().
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Move the assignment of the extent offset and length and payload
length out of rbd_req_sync_op() and into its caller in the one spot
where a read (and note--no write) operation might be initiated.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

In rbd_do_request() there's a sort of last-minute assignment of the
extent offset and length and payload length for read and write
operations.  Move those assignments into the caller (in those spots
that might initiate read or write operations)
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When rbd_req_sync_notify_ack() calls rbd_do_request() it supplies
rbd_simple_req_cb() as its callback function.  Because the callback
is supplied, an rbd_req structure gets allocated and populated so it
can be used by the callback.  However rbd_simple_req_cb() is not
freeing (or even using) the rbd_req structure, so it's getting
leaked.

Since rbd_simple_req_cb() has no need for the rbd_req structure,
just avoid allocating one for this case.  Of the three calls to
rbd_do_request(), only the one from rbd_do_op() needs the rbd_req
structure, and that call can be distinguished from the other two
because it supplies a non-null rbd_collection pointer.

So fix this leak by only allocating the rbd_req structure if a
non-null "coll" value is provided to rbd_do_request().
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When rbd_do_request() is called it allocates and populates an
rbd_req structure to hold information about the osd request to be
sent.  This is done for the benefit of the callback function (in
particular, rbd_req_cb()), which uses this in processing when
the request completes.

Synchronous requests provide no callback function, in which case
rbd_do_request() waits for the request to complete before returning.
This case is not handling the needed free of the rbd_req structure
like it should, so it is getting leaked.

Note however that the synchronous case has no need for the rbd_req
structure at all.  So rather than simply freeing this structure for
synchronous requests, just don't allocate it to begin with.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The rbd_req_sync_watch() and rbd_req_sync_unwatch() functions are
nearly identical.  Combine them into a single function with a flag
indicating whether a watch is to be initiated or torn down.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Each osd message includes a layout structure, and for rbd it is
always the same (at least for osd's in a given pool).

Initialize a layout structure when an rbd_dev gets created and just
copy that into osd requests for the rbd image.

Replace an assertion that was done when initializing the layout
structures with code that catches and handles anything that would
trigger the assertion as soon as it is identified.  This precludes
that (bad) condition from ever occurring.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When rbd_do_request() has a request to process it initializes a ceph
file layout structure and uses it to compute offsets and limits for
the range of the request using ceph_calc_file_object_mapping().

The layout used is fixed, and is based on RBD_MAX_OBJ_ORDER (30).
It sets the layout's object size and stripe unit to be 1 GB (2^30),
and sets the stripe count to be 1.

The job of ceph_calc_file_object_mapping() is to determine which
of a sequence of objects will contain data covered by range, and
within that object, at what offset the range starts.  It also
truncates the length of the range at the end of the selected object
if necessary.

This is needed for ceph fs, but for rbd it really serves no purpose.
It does its own blocking of images into objects, echo of which is
(1 << obj_order) in size, and as a result it ignores the "bno"
value returned by ceph_calc_file_object_mapping().  In addition,
by the point a request has reached this function, it is already
destined for a single rbd object, and its length will not exceed
that object's extent.  Because of this, and because the mapping will
result in blocking up the range using an integer multiple of the
image's object order, ceph_calc_file_object_mapping() will never
change the offset or length values defined by the request.

In other words, this call is a big no-op for rbd data requests.

There is one exception.  We read the header object using this
function, and in that case we will not have already limited the
request size.  However, the header is a single object (not a file or
rbd image), and should not be broken into pieces anyway.  So in fact
we should *not* be calling ceph_calc_file_object_mapping() when
operating on the header object.

So...

Don't call ceph_calc_file_object_mapping() in rbd_do_request(),
because useless for image data and incorrect to do sofor the image
header.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

This patch gets rid of rbd_calc_raw_layout() by simply open coding
it in its one caller.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>