nilfs2: fix hang-up of cleaner after log writer returned with error

According to the report from Andreas Beckmann (Message-ID:
<4BA54677.3090902@abeckmann.de>), nilfs in 2.6.33 kernel got stuck
after a disk full error.

This turned out to be a regression by log writer updates merged at
kernel 2.6.33.  nilfs_segctor_abort_construction, which is a cleanup
function for erroneous cases, was skipping writeback completion for
some logs.

This fixes the bug and would resolve the hang issue.

Reported-by: Andreas Beckmann <debian@abeckmann.de>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: stable <stable@kernel.org>                     [2.6.33.x]

fs/nilfs2/segment.c

@@ -1897,8 +1897,7 @@ static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
 
 	list_splice_tail_init(&sci->sc_write_logs, &logs);
 	ret = nilfs_wait_on_logs(&logs);
-	if (ret)
-		nilfs_abort_logs(&logs, NULL, sci->sc_super_root, ret);
+	nilfs_abort_logs(&logs, NULL, sci->sc_super_root, ret ? : err);
 
 	list_splice_tail_init(&sci->sc_segbufs, &logs);
 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);