os/FileJournal: logger is optional

Signed-off-by: Sage Weil <sage@inktank.com>
os/FileJournal: limit size of aio submission

Limit size of each aio submission to IOV_MAX-1 (to be safe).  Take care to
only mark the last aio with the seq to signal completion.

Signed-off-by: Sage Weil <sage@inktank.com>
test_filejournal: test journaling bl with >IOV_MAX segments

Signed-off-by: Sage Weil <sage@inktank.com>
test_filejournal: optionally specify journal filename as an argument

Signed-off-by: Sage Weil <sage@inktank.com>
Merge branch 'wip-journal-aio' into next

Reviewed-by: Samuel Just <sam.just@inktank.com>
Backport: bobtail
fuse: Fix cleanup code path on init failure

With the changes from 856f32ab, the cfuse.init call returns
a _positive_ errno, which was getting ignored.  Also, if an
error occurs during cfuse.init(), we need to teardown the client
mount.

Signed-off-by: Sam Lang <sam.lang@inktank.com>
log: fix locking typo/stupid for dump_recent()

We weren't locking m_flush_mutex properly, which in turn was leading to
racing threads calling dump_recent() and garbling the crash dump output.

Backport: bobtail, argonaut
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Merge remote-tracking branch 'gh/next'