generic/388 triggered a failure in RUI recovery due to a corrupted
btree record and the system then locked up hard due to a subsequent
assert failure while holding a spinlock cancelling intents:

 XFS (pmem1): Corruption of in-memory data (0x8) detected at xfs_do_force_shutdown+0x1a/0x20 (fs/xfs/xfs_trans.c:964).  Shutting down filesystem.
 XFS (pmem1): Please unmount the filesystem and rectify the problem(s)
 XFS: Assertion failed: !xlog_item_is_intent(lip), file: fs/xfs/xfs_log_recover.c, line: 2632
 Call Trace:
  <TASK>
  xlog_recover_cancel_intents.isra.0+0xd1/0x120
  xlog_recover_finish+0xb9/0x110
  xfs_log_mount_finish+0x15a/0x1e0
  xfs_mountfs+0x540/0x910
  xfs_fs_fill_super+0x476/0x830
  get_tree_bdev+0x171/0x270
  ? xfs_init_fs_context+0x1e0/0x1e0
  xfs_fs_get_tree+0x15/0x20
  vfs_get_tree+0x24/0xc0
  path_mount+0x304/0xba0
  ? putname+0x55/0x60
  __x64_sys_mount+0x108/0x140
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Essentially, there's dirty metadata in the AIL from intent recovery
transactions, so when we go to cancel the remaining intents we assume
that all objects after the first non-intent log item in the AIL are
not intents.

This is not true. Intent recovery can log new intents to continue
the operations the original intent could not complete in a single
transaction. The new intents are committed before they are deferred,
which means if the CIL commits in the background they will get
inserted into the AIL at the head.

Hence if we shut down the filesystem while processing intent
recovery, the AIL may have new intents active at the current head.
Hence this check:

                /*
                 * We're done when we see something other than an intent.
                 * There should be no intents left in the AIL now.
                 */
                if (!xlog_item_is_intent(lip)) {
#ifdef DEBUG
                        for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
                                ASSERT(!xlog_item_is_intent(lip));
#endif
                        break;
                }

in both xlog_recover_process_intents() and
log_recover_cancel_intents() is simply not valid. It was valid back
when we only had EFI/EFD intents and didn't chain intents, but it
hasn't been valid ever since intent recovery could create and commit
new intents.

Given that crashing the mount task like this pretty much prevents
diagnosing what went wrong that lead to the initial failure that
triggered intent cancellation, just remove the checks altogether.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>