linux/fs/jbd2
Xiaoguang Wang 53cf978457 jbd2: fix deadlock while checkpoint thread waits commit thread to finish
This issue was found when I tried to put checkpoint work in a separate thread,
the deadlock below happened:
         Thread1                                |   Thread2
__jbd2_log_wait_for_space                       |
jbd2_log_do_checkpoint (hold j_checkpoint_mutex)|
  if (jh->b_transaction != NULL)                |
    ...                                         |
    jbd2_log_start_commit(journal, tid);        |jbd2_update_log_tail
                                                |  will lock j_checkpoint_mutex,
                                                |  but will be blocked here.
                                                |
    jbd2_log_wait_commit(journal, tid);         |
    wait_event(journal->j_wait_done_commit,     |
     !tid_gt(tid, journal->j_commit_sequence)); |
     ...                                        |wake_up(j_wait_done_commit)
  }                                             |

then deadlock occurs, Thread1 will never be waken up.

To fix this issue, drop j_checkpoint_mutex in jbd2_log_do_checkpoint()
when we are going to wait for transaction commit.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-01-31 23:42:11 -05:00
..
checkpoint.c jbd2: fix deadlock while checkpoint thread waits commit thread to finish 2019-01-31 23:42:11 -05:00
commit.c jbd2: avoid long hold times of j_state_lock while committing a transaction 2018-12-03 23:16:07 -05:00
journal.c jbd2: fix deadlock while checkpoint thread waits commit thread to finish 2019-01-31 23:42:11 -05:00
Kconfig jbd2: remove debug dependency on debug_fs and update Kconfig help text 2013-06-12 23:07:51 -04:00
Makefile
recovery.c jbd2: clarify bad journal block checksum message 2018-02-18 21:33:13 -05:00
revoke.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
transaction.c jbd2: clean up indentation issue, replace spaces with tab 2018-12-04 00:20:10 -05:00