This ends up being a rather large patch but what it's doing is
somewhat straightforward.

Basically, this is replacing two calls with one.  The first of the
two calls is initializing a struct ceph_osd_data with data (either a
page array, a page list, or a bio list); the second is setting an
osd request op so it associates that data with one of the op's
parameters.  In place of those two will be a single function that
initializes the op directly.

That means we sort of fan out a set of the needed functions:
    - extent ops with pages data
    - extent ops with pagelist data
    - extent ops with bio list data
and
    - class ops with page data for receiving a response

We also have define another one, but it's only used internally:
    - class ops with pagelist data for request parameters

Note that we *still* haven't gotten rid of the osd request's
r_data_in and r_data_out fields.  All the osd ops refer to them for
their data.  For now, these data fields are pointers assigned to the
appropriate r_data_* field when these new functions are called.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

This patch just trivially moves around some code for consistency.

In preparation for initializing osd request data fields in
ceph_osdc_build_request(), I wanted to verify that rbd did in fact
call that immediately before it called ceph_osdc_start_request().
It was true (although image requests are built in a group and then
started as a group).  But I made the changes here just to make
it more obvious, by making all of the calls follow a common
sequence:
	osd_req_op_<optype>_init();
	ceph_osd_data_<type>_init()
	osd_req_op_<optype>_<datafield>()
	rbd_osd_req_format()
	...
	ret = rbd_obj_request_submit()

I moved the initialization of the callback for image object requests
into rbd_img_request_fill_bio(), again, for consistency.  To avoid
a forward reference, I moved the definition of rbd_img_obj_callback()
up in the file.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The osd data for a request is currently initialized inside
rbd_osd_req_create(), but that assumes an object request's data
belongs in the osd request's data in or data out field.

There are only three places where requests with data are set up, and
it turns out it's easier to call just the osd data init routines
directly there rather than handling it in rbd_osd_req_create().

(The real motivation here is moving toward getting rid of the
osd request in and out data fields.)
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Currently an object request has its osd request's data field set in
rbd_osd_req_format_op().  That assumes a single osd op per object
request, and that won't be the case for long.

Move the code that sets this out and into the caller.

Rename rbd_osd_req_format_op() to be just rbd_osd_req_format(),
removing the notion that it's doing anything op-specific.

This and the next patch resolve:
    http://tracker.ceph.com/issues/4658Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An osd request now holds all of its source op structures, and every
place that initializes one of these is in fact initializing one
of the entries in the the osd request's array.

So rather than supplying the address of the op to initialize, have
caller specify the osd request and an indication of which op it
would like to initialize.  This better hides the details the
op structure (and faciltates moving the data pointers they use).

Since osd_req_op_init() is a common routine, and it's not used
outside the osd client code, give it static scope.  Also make
it return the address of the specified op (so all the other
init routines don't have to repeat that code).
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An extent type osd operation currently implies that there will
be corresponding data supplied in the data portion of the request
(for write) or response (for read) message.  Similarly, an osd class
method operation implies a data item will be supplied to receive
the response data from the operation.

Add a ceph_osd_data pointer to each of those structures, and assign
it to point to eithre the incoming or the outgoing data structure in
the osd message.  The data is not always available when an op is
initially set up, so add two new functions to allow setting them
after the op has been initialized.

Begin to make use of the data item pointer available in the osd
operation rather than the request data in or out structure in
places where it's convenient.  Add some assertions to verify
pointers are always set the way they're expected to be.

This is a sort of stepping stone toward really moving the data
into the osd request ops, to allow for some validation before
making that jump.

This is the first in a series of patches that resolve:
    http://tracker.ceph.com/issues/4657Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An osd request keeps a pointer to the osd operations (ops) array
that it builds in its request message.

In order to allow each op in the array to have its own distinct
data, we will need to keep track of each op's data, and that
information does not go over the wire.

As long as we're tracking the data we might as well just track the
entire (source) op definition for each of the ops.  And if we're
doing that, we'll have no more need to keep a pointer to the
wire-encoded version.

This patch makes the array of source ops be kept with the osd
request structure, and uses that instead of the version encoded in
the message in places where that was previously used.  The array
will be embedded in the request structure, and the maximum number of
ops we ever actually use is currently 2.  So reduce CEPH_OSD_MAX_OP
to 2 to reduce the size of the structure.

The result of doing this sort of ripples back up, and as a result
various function parameters and local variables become unnecessary.

Make r_num_ops be unsigned, and move the definition of struct
ceph_osd_req_op earlier to ensure it's defined where needed.

It does not yet add per-op data, that's coming soon.

This resolves:
    http://tracker.ceph.com/issues/4656Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Define rbd_osd_req_format_op(), which encapsulates formatting
an osd op into an object request's osd request message.  Only
one op is supported right now.

Stop calling ceph_osdc_build_request() in rbd_osd_req_create().
Instead, call rbd_osd_req_format_op() in each of the callers of
rbd_osd_req_create().

This is to prepare for the next patch, in which the source ops for
an osd request will be held in the osd request itself.  Because of
that, we won't have the source op to work with until after the
request is created, so we can't format the op until then.

This an the next patch resolve:
    http://tracker.ceph.com/issues/4656Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Define and use functions that encapsulate the initializion of a
ceph_osd_data structure.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When rbd creates an object request containing an object method call
operation it is passing 0 for the size.  I originally thought this
was because the length was not needed for method calls, but I think
it really should be supplied, to describe how much space is
available to receive response data.  So provide the supplied length.

This resolves:
    http://tracker.ceph.com/issues/4659Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

When assigning a bio pointer to an osd request, we don't have an
efficient way of knowing the total length bytes in the bio list.
That information is available at the point it's set up by the rbd
code, so record it with the osd data when it's set.

This and the next patch are related to maintaining the length of a
message's data independent of the message header, as described here:
    http://tracker.ceph.com/issues/4589Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The rbd code has a function that allocates and populates a
ceph_osd_req_op structure (the in-core version of an osd request
operation).  When reviewed, Josh suggested two things: that the
big varargs function might be better split into type-specific
functions; and that this functionality really belongs in the osd
client rather than rbd.

This patch implements both of Josh's suggestions.  It breaks
up the rbd function into separate functions and defines them
in the osd client module as exported interfaces.  Unlike the
rbd version, however, the functions don't allocate an osd_req_op
structure; they are provided the address of one and that is
initialized instead.

The rbd function has been eliminated and calls to it have been
replaced by calls to the new routines.  The rbd code now now use a
stack (struct) variable to hold the op rather than allocating and
freeing it each time.

For now only the capabilities used by rbd are implemented.
Implementing all the other osd op types, and making the rest of the
code use it will be done separately, in the next few patches.

Note that only the extent, cls, and watch portions of the
ceph_osd_req_op structure are currently used.  Delete the others
(xattr, pgls, and snap) from its definition so nobody thinks it's
actually implemented or needed.  We can add it back again later
if needed, when we know it's been tested.

This (and a few follow-on patches) resolves:
    http://tracker.ceph.com/issues/3861Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Move some definitions for max integer values out of the rbd code and
into the more central "decode.h" header file.  These really belong
in a Linux (or libc) header somewhere, but I haven't gotten around
to proposing that yet.

This is in preparation for moving some code out of rbd.c and into
the osd client.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The length of outgoing data in an osd request is dependent on the
osd ops that are embedded in that request.  Each op is encoded into
a request message using osd_req_encode_op(), so that should be used
to determine the amount of outgoing data implied by the op as it
is encoded.

Have osd_req_encode_op() return the number of bytes of outgoing data
implied by the op being encoded, and accumulate and use that in
ceph_osdc_build_request().

As a result, ceph_osdc_build_request() no longer requires its "len"
parameter, so get rid of it.

Using the sum of the op lengths rather than the length provided is
a valid change because:
    - The only callers of osd ceph_osdc_build_request() are
      rbd and the osd client (in ceph_osdc_new_request() on
      behalf of the file system).
    - When rbd calls it, the length provided is only non-zero for
      write requests, and in that case the single op has the
      same length value as what was passed here.
    - When called from ceph_osdc_new_request(), (it's not all that
      easy to see, but) the length passed is also always the same
      as the extent length encoded in its (single) write op if
      present.

This resolves:
    http://tracker.ceph.com/issues/4406Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Record the byte count for an osd request rather than the page count.
The number of pages can always be derived from the byte count (and
alignment/offset) but the reverse is not true.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An osd request defines information about where data to be read
should be placed as well as where data to write comes from.
Currently these are represented by common fields.

Keep information about data for writing separate from data to be
read by splitting these into data_in and data_out fields.

This is the key patch in this whole series, in that it actually
identifies which osd requests generate outgoing data and which
generate incoming data.  It's less obvious (currently) that an osd
CALL op generates both outgoing and incoming data; that's the focus
of some upcoming work.

This resolves:
    http://tracker.ceph.com/issues/4127Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

An osd request uses either pages or a bio list for its data.  Use a
union to record information about the two, and add a data type
tag to select between them.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Pull the fields in an osd request structure that define the data for
the request out into a separate structure.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

It's possible that the reference to the object request dropped
inside the loop in rbd_img_request_submit() will be the last
one, in which case the content of the object pointer can't be
trusted.

Use a safe form of the object request list traversal to avoid
problems.

This resolves:
    http://tracker.ceph.com/issues/4705Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

A result of ENOENT from a read request for an object that's part of
an rbd image indicates that there is a hole in that portion of the
image.  Similarly, a short read for such an object indicates that
the remainder of the read should be interpreted a full read with
zeros filling out the end of the request.

This behavior is not correct for objects that are not backing rbd
image data.  Currently rbd_img_obj_request_callback() assumes it
should be done for all objects.

Change rbd_img_obj_request_callback() so it only does this zeroing
for image objects.  Encapsulate that special handling in its own
function.  Add an assertion that the image object request is a bio
request, since we assume that (and we currently don't support any
other types).

This resolves a problem identified here:
    http://tracker.ceph.com/issues/4559

The regression was introduced by bf0d5f50.
Reported-by: NDan van der Ster <dan@vanderster.com>
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-off-by: NSage Weil <sage@inktank.com>

Use the new version of the encoding for osd requests and replies.  In the
process, update the way we are tracking request ops and reply lengths and
results in the struct ceph_osd_request.  Update the rbd and fs/ceph users
appropriately.

The main changes are:
 - we keep pointers into the request memory for fields we need to update
   each time the request is sent out over the wire
 - we keep information about the result in an array in the request struct
   where the users can easily get at it.
Signed-off-by: NSage Weil <sage@inktank.com>
Reviewed-by: NAlex Elder <elder@inktank.com>

The only thing type-specific osd completion functions do with their
osd op parameter is (in some cases) extract the number of bytes
transferred from it.  In the other cases, the xferred bytes field
is not used, and total message data transfer byte count (which may
well be zero) is used.

Just set the object request transfer count in the main osd request
callback function and provide that to the other routines.  There is
then no longer any need to pass the op pointer to the type-specific
completion routines, so drop those parameters.

Stop doing anything with the total message data length.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

This function is slightly out of place, probably the result
of an errant automatic merge or something.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

Fengguang Wu reminded me that there were outstanding sparse reports
in the ceph and rbd code.  This patch fixes these problems in rbd
that lead to those reports:
    - Convert functions that are never referenced externally to have
      static scope.
    - Add a lockdep annotation to rbd_request_fn(), because it
      releases a lock before acquiring it again.

This partially resolves:
    http://tracker.ceph.com/issues/4184Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Add dout() calls to facilitate tracing of image and object requests.
Change a few existing calls so they use __func__ rather than the
hard-coded function name.  Have calls always add ":" after the name
of the function, and prefix pointer values with a consistent tag
indicating what it represents.  (Note that there remain some older
dout() calls that are left untouched by this patch.)

Issue a warning if rbd_osd_write_callback() ever gets a short write.

This resolves:
    http://tracker.ceph.com/issues/4235Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Let's go shopping!

I'm afraid this may not have gotten it right:
    07741308  rbd: add barriers near done flag operations

The smp_wmb() should have been done *before* setting the done flag,
to ensure all other data was valid before marking the object request
done.

Switch to use atomic_inc_return() here to set the done flag, which
allows us to verify we don't mark something done more than once.
Doing this also implies general barriers before and after the call.

And although a read memory barrier might have been sufficient before
reading the done flag, convert this to a full memory barrier just
to put this issue to bed.

This resolves:
    http://tracker.ceph.com/issues/4238Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The old request code simply ignored zero-length requests.  We should
still operate that same way to avoid any changes in behavior.  We
can implement handling for special zero-length requests separately
(see http://tracker.ceph.com/issues/4236).

Add some assertions based on this new constraint.

This resolves:
    http://tracker.ceph.com/issues/4237Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The return values provided for ceph_copy_to_page_vector() and
ceph_copy_from_page_vector() serve no purpose, so get rid of them.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

The result of ceph_copy_from_page_vector() is simply the length
argument it is provided.

This is called by rbd_obj_method_sync(), which returns the result if
it's non-negative.  But we always either ignore or overwrite that
return value.  So explicitly ignore what's returned by the copy
function, and have rbd_obj_method_sync() always return either a
negative errno or 0.

We also return the result of ceph_copy_from_page_vector() in
rbd_obj_read_sync().  There we still want to return the number of
bytes transferred, but we can use the value we already have in hand
rather than what ceph_copy_from_page_vector() provides.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

In rbd_obj_read_sync(), verify the number of bytes transferred won't
exceed what can be represented by a size_t before using it to
indicate the number of bytes to copy to the result buffer.

(The real motivation for this is to prepare for the next patch.)
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

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>