If the tcp connection drops and we reconnect to reestablish a stateful
session (with the mds), we need to resend previously sent (and possibly
received) messages with the _same_ seq # so that they can be dropped on
the other end if needed.  Only assign a new seq once after the message is
queued.

Signed-off-by: Sage Weil <sage@newdream.net>

The iterate_session_caps helper traverses the session caps list and tries
to grab an inode reference.  However, the __ceph_remove_cap was clearing
the inode backpointer _before_ removing itself from the session list,
causing a null pointer dereference.

Clear cap->ci under protection of s_cap_lock to avoid the race, and to
tightly couple the list and backpointer state.  Use a local flag to
indicate whether we are releasing the cap, as cap->session may be modified
by a racing thread in iterate_session_caps.

Signed-off-by: Sage Weil <sage@newdream.net>

We shouldn't leak any prior memory contents to other parties.  And random
data, particularly in the 'version' field, can cause problems down the
line.

Signed-off-by: Sage Weil <sage@newdream.net>

The session->s_waiting list is protected by mdsc->mutex, not s_mutex.  This
was causing (rare) s_waiting list corruption.

Fix errors paths too, while we're here.  A more thorough cleanup of this
function is coming soon.

Signed-off-by: Sage Weil <sage@newdream.net>

OSD requests need to be resubmitted on any pg mapping change, not just when
the pg primary changes.  Resending only when the primary changes results in
occasional 'hung' requests during osd cluster recovery or rebalancing.

Signed-off-by: Sage Weil <sage@newdream.net>

It's possible the MDS will not issue caps on a snapped inode, in which case
an open request may not __ceph_get_fmode(), botching the open file
counting.  (This is actually a server bug, but the client shouldn't BUG out
in this case.)

Signed-off-by: Sage Weil <sage@newdream.net>

The osd request wasn't being unregistered when the osd returned a failure
code, even though the result was returned to the caller.  This would cause
it to eventually time out, and then crash the kernel when it tried to
resend the request using a stale page vector.

Signed-off-by: Sage Weil <sage@newdream.net>

The ->writepages writeback_control is not still valid in the writepages
completion.  We were touching it solely to adjust pages_skipped when there
was a writeback error (EIO, ENOSPC, EPERM due to bad osd credentials),
causing an oops in the writeback code shortly thereafter.  Updating
pages_skipped on error isn't correct anyway, so let's just rip out this
(clearly broken) code to pass the wbc to the completion.

Signed-off-by: Sage Weil <sage@newdream.net>

Unregister and destroy the bdi in put_super, after mount is r/o, but before
put_anon_super releases the device name.

For symmetry, bdi_destroy in destroy_client (we bdi_init in create_client).

Only set s_bdi if bdi_register succeeds, since we use it to decide whether
to bdi_unregister.

Signed-off-by: Sage Weil <sage@newdream.net>

It's useless, since our allocations are already a power of 2.  And it was
allocated per-instance (not globally), which caused a name collision when
we tried to mount a second file system with auth_x enabled.

Signed-off-by: Sage Weil <sage@newdream.net>