Add a new parameter to __rbd_refresh_header() through which the
version of the header object is passed back to the caller.  In most
cases this isn't needed.  The main motivation is to normalize
(almost) all calls to __rbd_refresh_header() so they are all
wrapped immediately by mutex_lock()/mutex_unlock().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

This fixes a few issues in rbd_header_from_disk():
    - There is a check intended to catch overflow, but it's wrong in
      two ways.
	- First, the type we don't want to overflow is size_t, not
	  unsigned int, and there is now a SIZE_MAX we can use for
	  use with that type.
	- Second, we're allocating the snapshot ids and snapshot
	  image sizes separately (each has type u64; on disk they
          grouped together as a rbd_image_header_ondisk structure).
	  So we can use the size of u64 in this overflow check.
    - If there are no snapshots, then there should be no snapshot
      names.  Enforce this, and issue a warning if we encounter a
      header with no snapshots but a non-zero snap_names_len.
    - When saving the snapshot names into the header, be more direct
      in defining the offset in the on-disk structure from which
      they're being copied by using "snap_count" rather than "i"
      in the array index.
    - If an error occurs, the "snapc" and "snap_names" fields are
      freed at the end of the function.  Make those fields be null
      pointers after they're freed, to be explicit that they are
      no longer valid.
    - Finally, move the definition of the local variable "i" to the
      innermost scope in which it's needed.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

All of the callers of rbd_req_sync_op() except one pass a non-null
"ops" pointer.  The only one that does not is rbd_req_sync_read(),
which passes CEPH_OSD_OP_READ as its "opcode" and, CEPH_OSD_FLAG_READ
for "flags".

By allocating the ops array in rbd_req_sync_read() and moving the
special case code for the null ops pointer into it, it becomes
clear that much of that code is not even necessary.

In addition, the "opcode" argument to rbd_req_sync_op() is never
actually used, so get rid of that.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

rbd_header_add_snap() passes the address of a version variable to
rbd_req_sync_exec(), but it ignores the result.  Just pass a null
pointer instead.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

Either rbd_create_rw_ops() will succeed, or it will fail because a
memory allocation failed.  Have it just return a valid pointer or
null rather than stuffing a pointer into a provided address and
returning an errno.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

It's not obvious whether the snapshot pointer whose address is
provided to __rbd_add_snap_dev() will be assigned by that function.
Change it to return the snapshot, or a pointer-coded errno in the
event of a failure.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

We drop the lock when calling the ->alloc_msg() con op, which means
we need to (a) not clobber con->in_msg without the mutex held, and (b)
we need to verify that we are still in the OPEN state when we retake
it to avoid causing any mayhem.  If the state does change, -EAGAIN
will get us back to con_work() and loop.
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

This function's calling convention is very limiting.  In particular,
we can't return any error other than ENOMEM (and only implicitly),
which is a problem (see next patch).

Instead, return an normal 0 or error code, and make the skip a pointer
output parameter.  Drop the useless in_hdr argument (we have the con
pointer).
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

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

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

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

Revoke all mon_client messages when we shut down the old connection.
This is mostly moot since we are re-using the same ceph_connection,
but it is cleaner.
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

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

 * shiny new inktank.com email addresses
 * add include/linux/crush directory (previous oversight)
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

There are many (normal) conditions that can lead to us getting
unexpected replies, include cluster topology changes, osd failures,
and timeouts.  There's no need to spam the console about it.
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

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

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

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

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

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

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

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

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

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

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

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

rbd_req_sync_unwatch() only ever uses rbd_dev->header_name as the
value of its "object_name" parameter, and that value is available
within the function already.  So get rid of the parameter.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

rbd_req_sync_notify_ack() only ever uses rbd_dev->header_name as the
value of its "object_name" parameter, and that value is available
within the function already.  So get rid of the parameter.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

rbd_req_sync_notify() only ever uses rbd_dev->header_name as the
value of its "object_name" parameter, and that value is available
within the function already.  So get rid of the parameter.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

rbd_req_sync_watch() is only called in one place, and in that place
it passes rbd_dev->header_name as the value of the "object_name"
parameter.  This value is available within the function already.

Having the extra parameter leaves the impression the object name
could take on different values, but it does not.

So get rid of the parameter.  We can always add it back again if
we find we want to watch some other object in the future.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Both rbd_register_snap_dev() and __rbd_remove_snap_dev() have
rbd_dev parameters that are unused.  Remove them.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The function rbd_header_from_disk() is only called in one spot, and
it passes GFP_KERNEL as its value for the gfp_flags parameter.

Just drop that parameter and substitute GFP_KERNEL everywhere within
that function it had been used.  (If we find we need the parameter
again in the future it's easy enough to add back again.)
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The "snapc" parameter to in rbd_req_sync_read() is not used, so
get rid of it.
Reported-by: Josh Durgin <josh.durgin@inktank.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The "id" field of an rbd device structure represents the unique
client-local device id mapped to the underlying rbd image.  Each rbd
image will have another id--the image id--and each snapshot has its
own id as well.  The simple name "id" no longer conveys the
information one might like to have.

Rename the device "id" field in struct rbd_dev to be "dev_id" to
make it a little more obvious what we're dealing with without having
to think more about context.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

If an rbd image header is read and it doesn't begin with the
expected magic information, a warning is displayed.  This is
a fairly simple test, but it could be extended at some point.
Fix the comparison so it actually looks at the "text" field
rather than the front of the structure.

In any case, encapsulate the validity test in its own function.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There are two structures in which a count of snapshots are
maintained:

    struct ceph_snap_context {
	...
        u32 num_snaps;
	...
    }
and
    struct ceph_snap_realm {
	...
        u32 num_prior_parent_snaps;   /*  had prior to parent_since */
	...
        u32 num_snaps;
	...
    }

These fields never take on negative values (e.g., to hold special
meaning), and so are really inherently unsigned.  Furthermore they
take their value from over-the-wire or on-disk formatted 32-bit
values.

So change their definition to have type u32, and change some spots
elsewhere in the code to account for this change.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

There was a dout() call in rbd_do_request() that was reporting
the reporting the offset as the length and vice versa.  While
fixing that I did a quick scan of other dout() calls and fixed
a couple of other minor things.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

This just replaces a while loop with list_for_each_entry_safe()
in __rbd_remove_all_snaps().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

In commit c666601a there was inadvertently added an extra
initialization of rbd_dev->header_rwsem.  This gets rid of the
duplicate.
Reported-by: Guangliang Zhao <gzhao@suse.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

The snap_seq field in an rbd_image_header structure held the value
from the rbd image header when it was last refreshed.  We now
maintain this value in the snapc->seq field.  So get rid of the
other one.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

In rbd_header_add_snap() there is code to set snapc->seq to the
just-added snapshot id.  This is the only remnant left of the
use of that field for recording which snapshot an rbd_dev was
associated with.  That functionality is no longer supported,
so get rid of that final bit of code.

Doing so means we never actually set snapc->seq any more.  On the
server, the snapshot context's sequence value represents the highest
snapshot id ever issued for a particular rbd image.  So we'll make
it have that meaning here as well.  To do so, set this value
whenever the rbd header is (re-)read.  That way it will always be
consistent with the rest of the snapshot context we maintain.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

In rbd_header_set_snap(), there is logic to make the snap context's
seq field get set to a particular snapshot id, or 0 if there is no
snapshot for the rbd image.

This seems to be an artifact of how the current snapshot id for an
rbd_dev was recorded before the rbd_dev->snap_id field began to be
used for that purpose.

There's no need to update the value of snapc->seq here any more, so
stop doing it.  Tidy up a few local variables in that function
while we're at it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

In what appears to be an artifact of a different way of encoding
whether an rbd image maps a snapshot, __rbd_refresh_header() has
code that arranges to update the seq value in an rbd image's
snapshot context to point to the first entry in its snapshot
array if that's where it was pointing initially.

We now use rbd_dev->snap_id to record the snapshot id--using the
special value CEPH_NOSNAP to indicate the rbd_dev is not mapping a
snapshot at all.

There is therefore no need to check for this case, nor to update the
seq value, in __rbd_refresh_header().  Just preserve the seq value
that rbd_read_header() provides (which, at the moment, is nothing).
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>