osdc/ObjectCacher: call read completion even when no target buffer

If we do no assemble a target bl, we still want to return a valid return
code with the number of bytes read-ahead so that the C_RetryRead completion
will see this as a finish and call the caller's provided Context.

Signed-off-by: Sage Weil <sage@inktank.com>
client: pin Inode during readahead

Make sure the Inode does not go away while a readahead is in progress.  In
particular:

 - read_async
   - start a readahead
   - get actual read from cache, return
 - close/release
   - call ObjectCacher::release_set() and get unclean > 0, assert

Fixes: #7867
Backport: emperor, dumpling
Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #1557 from ceph/wip-7867

client: fix assert(!unclean) due to readahead vs close race

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
ReplicatedPG: hit_set_setup, agent_setup, skip if !active

We call these in on_activate and on_pool_change.  In the former, we are
necessarily active.  In the latter, we only want to do anything if we are
active (otherwise, it will be taken care of when we eventually do become
active).

Fixes: #7904
Signed-off-by: Samuel Just <sam.just@inktank.com>
Merge remote-tracking branches 'origin/wip-sam-testing2', 'upstream/wip-7659', 'origin/wip-7904', 'origin/wip-7858', 'origin/wip-7837' and 'origin/wip-7831' into wip-sam-testing