• Dave Chinner's avatar
    xfs: lockdep needs to know about 3 dquot-deep nesting · 89c6c89a
    Dave Chinner authored
    Michael Semon reported that xfs/299 generated this lockdep warning:
    
    =============================================
    [ INFO: possible recursive locking detected ]
    3.12.0-rc2+ #2 Not tainted
    ---------------------------------------------
    touch/21072 is trying to acquire lock:
     (&xfs_dquot_other_class){+.+...}, at: [<c12902fb>] xfs_trans_dqlockedjoin+0x57/0x64
    
    but task is already holding lock:
     (&xfs_dquot_other_class){+.+...}, at: [<c12902fb>] xfs_trans_dqlockedjoin+0x57/0x64
    
    other info that might help us debug this:
     Possible unsafe locking scenario:
    
           CPU0
           ----
      lock(&xfs_dquot_other_class);
      lock(&xfs_dquot_other_class);
    
     *** DEADLOCK ***
    
     May be due to missing lock nesting notation
    
    7 locks held by touch/21072:
     #0:  (sb_writers#10){++++.+}, at: [<c11185b6>] mnt_want_write+0x1e/0x3e
     #1:  (&type->i_mutex_dir_key#4){+.+.+.}, at: [<c11078ee>] do_last+0x245/0xe40
     #2:  (sb_internal#2){++++.+}, at: [<c122c9e0>] xfs_trans_alloc+0x1f/0x35
     #3:  (&(&ip->i_lock)->mr_lock/1){+.+...}, at: [<c126cd1b>] xfs_ilock+0x100/0x1f1
     #4:  (&(&ip->i_lock)->mr_lock){++++-.}, at: [<c126cf52>] xfs_ilock_nowait+0x105/0x22f
     #5:  (&dqp->q_qlock){+.+...}, at: [<c12902fb>] xfs_trans_dqlockedjoin+0x57/0x64
     #6:  (&xfs_dquot_other_class){+.+...}, at: [<c12902fb>] xfs_trans_dqlockedjoin+0x57/0x64
    
    The lockdep annotation for dquot lock nesting only understands
    locking for user and "other" dquots, not user, group and quota
    dquots. Fix the annotations to match the locking heirarchy we now
    have.
    Reported-by: default avatarMichael L. Semon <mlsemon35@gmail.com>
    Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
    Reviewed-by: default avatarBen Myers <bpm@sgi.com>
    Signed-off-by: default avatarBen Myers <bpm@sgi.com>
    
    (cherry picked from commit f112a049)
    89c6c89a
xfs_dquot.c 31.2 KB