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Subject[BUG] fs: ocfs2: possible ABBA deadlock in ocfs2_dio_end_io_write() and ocfs2_move_extents()
Date
Hello,

My static analysis tool reports a possible ABBA deadlock in the ocfs2
module in Linux 5.10:

ocfs2_dio_end_io_write()
  down_write(&oi->ip_alloc_sem); --> Line 2322 (Lock A)
  ocfs2_del_inode_from_orphan()
    inode_lock(orphan_dir_inode);  --> Line 2701 (Lock B)

ocfs2_move_extents()
  inode_lock(inode); --> Line 916 (Lock B)
  down_write(&OCFS2_I(inode)->ip_alloc_sem); --> Line 936 (Lock A)

When ocfs2_dio_end_io_write() and ocfs2_move_extents() are concurrently
executed, the deadlocks can occur.

I am not quite sure whether this possible deadlock is real and how to
fix it if it is real.
Any feedback would be appreciated, thanks :)

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>


Best wishes,
Jia-Ju Bai

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