• Daeho Jeong's avatar
    ext4, jbd2: ensure entering into panic after recording an error in superblock · 08c89a61
    Daeho Jeong authored
    commit 4327ba52 upstream.
    
    If a EXT4 filesystem utilizes JBD2 journaling and an error occurs, the
    journaling will be aborted first and the error number will be recorded
    into JBD2 superblock and, finally, the system will enter into the
    panic state in "errors=panic" option.  But, in the rare case, this
    sequence is little twisted like the below figure and it will happen
    that the system enters into panic state, which means the system reset
    in mobile environment, before completion of recording an error in the
    journal superblock. In this case, e2fsck cannot recognize that the
    filesystem failure occurred in the previous run and the corruption
    wouldn't be fixed.
    
    Task A                        Task B
    ext4_handle_error()
    -> jbd2_journal_abort()
      -> __journal_abort_soft()
        -> __jbd2_journal_abort_hard()
        | -> journal->j_flags |= JBD2_ABORT;
        |
        |                         __ext4_abort()
        |                         -> jbd2_journal_abort()
        |                         | -> __journal_abort_soft()
        |                         |   -> if (journal->j_flags & JBD2_ABORT)
        |                         |           return;
        |                         -> panic()
        |
        -> jbd2_journal_update_sb_errno()
    Tested-by: default avatarHobin Woo <hobin.woo@samsung.com>
    Signed-off-by: default avatarDaeho Jeong <daeho.jeong@samsung.com>
    Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
    08c89a61
super.c 144 KB