ocfs2: fix a tiny race when running dirop_fileop_racer

When running dirop_fileop_racer we found a dead lock case.

2 nodes, say Node A and Node B, mount the same ocfs2 volume.  Create
/race/16/1 in the filesystem, and let the inode number of dir 16 is less
than the inode number of dir race.

Node A                            Node B
mv /race/16/1 /race/
                                  right after Node A has got the
                                  EX mode of /race/16/, and tries to
                                  get EX mode of /race
                                  ls /race/16/

In this case, Node A has got the EX mode of /race/16/, and wants to get EX
mode of /race/.  Node B has got the PR mode of /race/, and wants to get
the PR mode of /race/16/.  Since EX and PR are mutually exclusive, dead
lock happens.

This patch fixes this case by locking in ancestor order before trying
inode number order.

Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
index 1b60c62..6cb019b 100644
--- a/fs/ocfs2/ocfs2_trace.h
+++ b/fs/ocfs2/ocfs2_trace.h
@@ -2292,6 +2292,8 @@ TRACE_EVENT(ocfs2_rename,
 		  __entry->new_len, __get_str(new_name))
 );
 
+DEFINE_OCFS2_ULL_ULL_EVENT(ocfs2_rename_not_permitted);
+
 TRACE_EVENT(ocfs2_rename_target_exists,
 	TP_PROTO(int new_len, const char *new_name),
 	TP_ARGS(new_len, new_name),