The flags field of struct ceph_osd_req_op is never used, so just get
rid of it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

We now know that every of rbd_req_sync_op() passes an array of
exactly one operation, as evidenced by all callers passing 1 as its
num_op argument.  So get rid of that argument, assuming a single op.

Similarly, we now know that all callers of rbd_do_request() pass 1
as the num_op value, so that parameter can be eliminated as well.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Throughout the rbd code there are spots where it appears we can
handle an osd request containing more than one osd request op.

But that is only the way it appears.  In fact, currently only one
operation at a time can be supported, and supporting more than
one will require much more than fleshing out the support that's
there now.

This patch changes names to make it perfectly clear that anywhere
we're dealing with a block of ops, we're in fact dealing with
exactly one of them.  We'll be able to simplify some things as
a result.

When multiple op support is implemented, we can update things again
accordingly.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Both ceph_osdc_alloc_request() and ceph_osdc_build_request() are
provided an array of ceph osd request operations.  Rather than just
passing the number of operations in the array, the caller is
required append an additional zeroed operation structure to signal
the end of the array.

All callers know the number of operations at the time these
functions are called, so drop the silly zero entry and supply that
number directly.  As a result, get_num_ops() is no longer needed.
This also means that ceph_osdc_alloc_request() never uses its ops
argument, so that can be dropped.

Also rbd_create_rw_ops() no longer needs to add one to reserve room
for the additional op.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Add a num_op parameter to rbd_do_request() and rbd_req_sync_op() to
indicate the number of entries in the array.  The callers of these
functions always know how many entries are in the array, so just
pass that information down.

This is in anticipation of eliminating the extra zero-filled entry
in these ops arrays.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Only one of the two callers of ceph_osdc_alloc_request() provides
page or bio data for its payload.  And essentially all that function
was doing with those arguments was assigning them to fields in the
osd request structure.

Simplify ceph_osdc_alloc_request() by having the caller take care of
making those assignments
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The only thing ceph_osdc_alloc_request() really does with the
flags value it is passed is assign it to the newly-created
osd request structure.  Do that in the caller instead.

Both callers subsequently call ceph_osdc_build_request(), so have
that function (instead of ceph_osdc_alloc_request()) issue a warning
if a request comes through with neither the read nor write flags set.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The osdc parameter to ceph_calc_raw_layout() is not used, so get rid
of it.  Consequently, the corresponding parameter in calc_layout()
becomes unused, so get rid of that as well.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

A snapshot id must be provided to ceph_calc_raw_layout() even though
it is not needed at all for calculating the layout.

Where the snapshot id *is* needed is when building the request
message for an osd operation.

Drop the snapid parameter from ceph_calc_raw_layout() and pass
that value instead in ceph_osdc_build_request().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

ceph_calc_file_object_mapping() takes (among other things) a "file"
offset and length, and based on the layout, determines the object
number ("bno") backing the affected portion of the file's data and
the offset into that object where the desired range begins.  It also
computes the size that should be used for the request--either the
amount requested or something less if that would exceed the end of
the object.

This patch changes the input length parameter in this function so it
is used only for input.  That is, the argument will be passed by
value rather than by address, so the value provided won't get
updated by the function.

The value would only get updated if the length would surpass the
current object, and in that case the value it got updated to would
be exactly that returned in *oxlen.

Only one of the two callers is affected by this change.  Update
ceph_calc_raw_layout() so it records any updated value.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The len argument to ceph_osdc_build_request() is set up to be
passed by address, but that function never updates its value
so there's no need to do this.  Tighten up the interface by
passing the length directly.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Since every osd message is now prepared to include trailing data,
there's no need to check ahead of time whether any operations will
make use of the trail portion of the message.

We can drop the second argument to get_num_ops(), and as a result we
can also get rid of op_needs_trail() which is no longer used.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

An osd request structure contains an optional trail portion, which
if present will contain data to be passed in the payload portion of
the message containing the request.  The trail field is a
ceph_pagelist pointer, and if null it indicates there is no trail.

A ceph_pagelist structure contains a length field, and it can
legitimately hold value 0.  Make use of this to change the
interpretation of the "trail" of an osd request so that every osd
request has trailing data, it just might have length 0.

This means we change the r_trail field in a ceph_osd_request
structure from a pointer to a structure that is always initialized.

Note that in ceph_osdc_start_request(), the trail pointer (or now
address of that structure) is assigned to a ceph message's trail
field.  Here's why that's still OK (looking at net/ceph/messenger.c):
    - What would have resulted in a null pointer previously will now
      refer to a 0-length page list.  That message trail pointer
      is used in two functions, write_partial_msg_pages() and
      out_msg_pos_next().
    - In write_partial_msg_pages(), a null page list pointer is
      handled the same as a message with 0-length trail, and both
      result in a "in_trail" variable set to false.  The trail
      pointer is only used if in_trail is true.
    - The only other place the message trail pointer is used is
      out_msg_pos_next().  That function is only called by
      write_partial_msg_pages() and only touches the trail pointer
      if the in_trail value it is passed is true.
Therefore a null ceph_msg->trail pointer is equivalent to a non-null
pointer referring to a 0-length page list structure.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

For some reason, the snapid field of the osd request header is
explicitly set to CEPH_NOSNAP in rbd_do_request().  Just a few lines
later--with no code that would access this field in between--a call
is made to ceph_calc_raw_layout() passing the snapid provided to
rbd_do_request(), which encodes the snapid value it is provided into
that field instead.

In other words, there is no need to fill in CEPH_NOSNAP, and doing
so suggests it might be necessary.  Don't do that any more.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The snapc and snapid parameters to rbd_req_sync_op() always take
the values NULL and CEPH_NOSNAP, respectively.  So just get rid
of them and use those values where needed.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

All callers of rbd_req_sync_exec() pass CEPH_OSD_FLAG_READ as their
flags argument.  Delete that parameter and use CEPH_OSD_FLAG_READ
within the function.  If we find a need to support write operations
we can add it back again.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There is only one caller of rbd_req_sync_read(), and it passes
CEPH_NOSNAP as the snapshot id argument.  Delete that parameter
and just use CEPH_NOSNAP within the function.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The last two parameters to ceph_osd_build_request() describe the
object id, but the values passed always come from the osd request
structure whose address is also provided.  Get rid of those last
two parameters.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Pull a block of code that initializes the layout structure in an osd
request into its own function so it can be reused.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Right now we get the snapshot context for an rbd image (under
protection of the header semaphore) for every request processed.

There's no need to get the snap context if we're doing a read,
so avoid doing so in that case.

Note that we no longer need to hold the header semaphore to
check the rbd_dev's existence flag.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The rbd_device->exists field can be updated asynchronously, changing
from set to clear if a mapped snapshot disappears from the base
image's snapshot context.

Currently, value of the "exists" flag is only read and modified
under protection of the header semaphore, but that will change with
the next patch.  Making it atomic ensures this won't be a problem
because the a the non-existence of device will be immediately known.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Now that a big hunk in the middle of rbd_rq_fn() has been moved
into its own routine we can simplify it a little more.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Only one of the three callers of rbd_do_request() provide a
collection structure to aggregate status.

If an error occurs in rbd_do_request(), have the caller
take care of calling rbd_coll_end_req() if necessary in
that one spot.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

In rbd_rq_fn(), requests are fetched from the block layer and each
request is processed, looping through the request's list of bio's
until they've all been consumed.

Separate the handling for a single request into its own function to
make it a bit easier to see what's going on.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The result field in a ceph osd reply header is a signed 32-bit type,
but rbd code often casually uses int to represent it.

The following changes the types of variables that handle this result
value to be "s32" instead of "int" to be completely explicit about
it.  Only at the point we pass that result to __blk_end_request()
does the type get converted to the plain old int defined for that
interface.

There is almost certainly no binary impact of this change, but I
prefer to show the exact size and signedness of the value since we
know it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>

There are spots where a ceph_osds_request pointer variable is given
the name "req".  Since we're dealing with (at least) three types of
requests (block layer, rbd, and osd), I find this slightly
distracting.

Change such instances to use "osd_req" consistently to make the
abstraction represented a little more obvious.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There are two names used for items of rbd_request structure type:
"req" and "req_data".  The former name is also used to represent
items of pointers to struct ceph_osd_request.

Change all variables that have these names so they are instead
called "rbd_req" consistently.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Josh suggested adding warnings to this function to help users
diagnose problems.

Other than memory allocatino errors, there are two places where
errors can be returned.  Both represent problems that should
have been caught earlier, and as such might well have been
handled with BUG_ON() calls.  But if either ever did manage to
happen, it will be reported.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Add a warning in bio_chain_clone_range() to help a user determine
what exactly might have led to a failure.  There is only one; please
say something if you disagree with the following reasoning.

There are three places this can return abnormally:
    - Initially, if there is nothing to clone.  It turns out that
      right now this cannot happen anyway.  The test is in place
      because the code below it doesn't work if those conditions
      don't hold.  As such they could be assertions but since I can
      return a null to indicate an error I just do that instead.
      I have not added a warning here because it won't happen.
    - While processing bio's, if none remain but there are supposed
      to be more bytes to clone.  Here I have added a warning.
    - If bio_clone_range() returns a null pointer.  That function
      will have already produced a warning (at least the first
      time, via WARN_ON_ONCE()) to distinguish the cause of the
      error.  The only exception is memory exhaustion, and I'd
      rather not pepper the code with warnings in all those spots.
      So no warning is added in that place.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Tell the user (via dmesg) what was wrong with the arguments provided
via /sys/bus/rbd/add.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>

Define a new function rbd_warn() that produces a boilerplate warning
message, identifying in the resulting message the affected rbd
device in the best way available.  Use it in a few places that now
use pr_warning().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

It's kind of a silly macro, but ceph_encode_8_safe() is the only one
missing from an otherwise pretty complete set.  It's not used, but
neither are a couple of the others in this set.

While in there, insert some whitespace to tidy up the alignment of
the line-terminating backslashes in some of the macro definitions.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>

This replaces two kmalloc()/memcpy() combinations with a single
call to kmemdup().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: David Zafman <david.zafman@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There is no real benefit to keeping the length of an image id, so
get rid of it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: David Zafman <david.zafman@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There may have been a benefit to hanging on to the length of an
image name before, but there is really none now.  The only time it's
used is when probing for rbd images, so we can just compute the
length then.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: David Zafman <david.zafman@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

I promised Josh I would document whether there were any restrictions
needed for accessing fields of an rbd_spec structure.  This adds a
big block of comments that documents the structure and how it is
used--including the fact that we don't attempt to synchronize access
to it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: David Zafman <david.zafman@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Reformat __reset_osd() into three distinct blocks of code
handling the three return cases.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

This saves us some cycles, but does not affect the placement result at
all.

This corresponds to ceph.git commit 4abb53d4f.
Signed-off-by: Sage Weil <sage@inktank.com>

Add libceph support for a new CRUSH tunable recently added to Ceph servers.

Consider the CRUSH rule
  step chooseleaf firstn 0 type <node_type>

This rule means that <n> replicas will be chosen in a manner such that
each chosen leaf's branch will contain a unique instance of <node_type>.

When an object is re-replicated after a leaf failure, if the CRUSH map uses
a chooseleaf rule the remapped replica ends up under the <node_type> bucket
that held the failed leaf.  This causes uneven data distribution across the
storage cluster, to the point that when all the leaves but one fail under a
particular <node_type> bucket, that remaining leaf holds all the data from
its failed peers.

This behavior also limits the number of peers that can participate in the
re-replication of the data held by the failed leaf, which increases the
time required to re-replicate after a failure.

For a chooseleaf CRUSH rule, the tree descent has two steps: call them the
inner and outer descents.

If the tree descent down to <node_type> is the outer descent, and the descent
from <node_type> down to a leaf is the inner descent, the issue is that a
down leaf is detected on the inner descent, so only the inner descent is
retried.

In order to disperse re-replicated data as widely as possible across a
storage cluster after a failure, we want to retry the outer descent. So,
fix up crush_choose() to allow the inner descent to return immediately on
choosing a failed leaf.  Wire this up as a new CRUSH tunable.

Note that after this change, for a chooseleaf rule, if the primary OSD
in a placement group has failed, choosing a replacement may result in
one of the other OSDs in the PG colliding with the new primary.  This
requires that OSD's data for that PG to need moving as well.  This
seems unavoidable but should be relatively rare.

This corresponds to ceph.git commit 88f218181a9e6d2292e2697fc93797d0f6d6e5dc.
Signed-off-by: Jim Schutt <jaschut@sandia.gov>
Reviewed-by: Sage Weil <sage@inktank.com>

The MDS may have incorrect wanted caps after importing caps. So the
client should check the value mds has and send cap update if necessary.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>