ocfs2: dlm: fix lock migration crash

commit 34aa8dac482f1358d59110d5e3a12f4351f6acaa upstream.

This issue was introduced by commit 800deef3f6f8 ("ocfs2: use
list_for_each_entry where benefical") in 2007 where it replaced
list_for_each with list_for_each_entry.  The variable "lock" will point
to invalid data if "tmpq" list is empty and a panic will be triggered
due to this.  Sunil advised reverting it back, but the old version was
also not right.  At the end of the outer for loop, that
list_for_each_entry will also set "lock" to an invalid data, then in the
next loop, if the "tmpq" list is empty, "lock" will be an stale invalid
data and cause the panic.  So reverting the list_for_each back and reset
"lock" to NULL to fix this issue.

Another concern is that this seemes can not happen because the "tmpq"
list should not be empty.  Let me describe how.

old lock resource owner(node 1):                                  migratation target(node 2):
image there's lockres with a EX lock from node 2 in
granted list, a NR lock from node x with convert_type
EX in converting list.
dlm_empty_lockres() {
 dlm_pick_migration_target() {
   pick node 2 as target as its lock is the first one
   in granted list.
 }
 dlm_migrate_lockres() {
   dlm_mark_lockres_migrating() {
     res->state |= DLM_LOCK_RES_BLOCK_DIRTY;
     wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
	 //after the above code, we can not dirty lockres any more,
     // so dlm_thread shuffle list will not run
                                                                   downconvert lock from EX to NR
                                                                   upconvert lock from NR to EX
<<< migration may schedule out here, then
<<< node 2 send down convert request to convert type from EX to
<<< NR, then send up convert request to convert type from NR to
<<< EX, at this time, lockres granted list is empty, and two locks
<<< in the converting list, node x up convert lock followed by
<<< node 2 up convert lock.

	 // will set lockres RES_MIGRATING flag, the following
	 // lock/unlock can not run
     dlm_lockres_release_ast(dlm, res);
   }

   dlm_send_one_lockres()
                                                                 dlm_process_recovery_data()
                                                                   for (i=0; i<mres->num_locks; i++)
                                                                     if (ml->node == dlm->node_num)
                                                                       for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
                                                                        list_for_each_entry(lock, tmpq, list)
                                                                        if (lock) break; <<< lock is invalid as grant list is empty.
                                                                       }
                                                                       if (lock->ml.node != ml->node)
                                                                         BUG() >>> crash here
 }

I see the above locks status from a vmcore of our internal bug.

Change-Id: Ia516ae5b2eba8a7f11910f8bb7d3cd3f0c17c834
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Wengang Wang <wen.gang.wang@oracle.com>
Cc: Sunil Mushran <sunil.mushran@gmail.com>
Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ocfs2: dlm: fix recovery hung

commit ded2cf71419b9353060e633b59e446c42a6a2a09 upstream.

There is a race window in dlm_do_recovery() between dlm_remaster_locks()
and dlm_reset_recovery() when the recovery master nearly finish the
recovery process for a dead node.  After the master sends FINALIZE_RECO
message in dlm_remaster_locks(), another node may become the recovery
master for another dead node, and then send the BEGIN_RECO message to
all the nodes included the old master, in the handler of this message
dlm_begin_reco_handler() of old master, dlm->reco.dead_node and
dlm->reco.new_master will be set to the second dead node and the new
master, then in dlm_reset_recovery(), these two variables will be reset
to default value.  This will cause new recovery master can not finish
the recovery process and hung, at last the whole cluster will hung for
recovery.

old recovery master:                                 new recovery master:
dlm_remaster_locks()
                                                  become recovery master for
                                                  another dead node.
                                                  dlm_send_begin_reco_message()
dlm_begin_reco_handler()
{
 if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
  return -EAGAIN;
 }
 dlm_set_reco_master(dlm, br->node_idx);
 dlm_set_reco_dead_node(dlm, br->dead_node);
}
dlm_reset_recovery()
{
 dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
 dlm_set_reco_master(dlm, O2NM_INVALID_NODE_NUM);
}
                                                  will hang in dlm_remaster_locks() for
                                                  request dlm locks info

Before send FINALIZE_RECO message, recovery master should set
DLM_RECO_STATE_FINALIZE for itself and clear it after the recovery done,
this can break the race windows as the BEGIN_RECO messages will not be
handled before DLM_RECO_STATE_FINALIZE flag is cleared.

A similar race may happen between new recovery master and normal node
which is in dlm_finalize_reco_handler(), also fix it.

Change-Id: I2465df46f3de50db95262e112f171cfa9e3fb7c9
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Reviewed-by: Wengang Wang <wen.gang.wang@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ocfs2: do not put bh when buffer_uptodate failed

commit f7cf4f5bfe073ad792ab49c04f247626b3e38db6 upstream.

Do not put bh when buffer_uptodate failed in ocfs2_write_block and
ocfs2_write_super_or_backup, because it will put bh in b_end_io.
Otherwise it will hit a warning "VFS: brelse: Trying to free free
buffer".

Change-Id: I0c0c7370aa40e684af61c99791f21371d642065a
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: use i_size_read in ext4_unaligned_aio()

commit 6e6358fc3c3c862bfe9a5bc029d3f8ce43dc9765 upstream.

We haven't taken i_mutex yet, so we need to use i_size_read().

Change-Id: I111b174f5260e71b5494df79da928c73d5045a86
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>