Commit a75e9cca authored by Srinivas Eeda's avatar Srinivas Eeda Committed by Joel Becker
Browse files

ocfs2: use spinlock irqsave for downconvert lock.patch 



When ocfs2dc thread holds dc_task_lock spinlock and receives soft IRQ it
deadlock itself trying to get same spinlock in ocfs2_wake_downconvert_thread.
Below is the stack snippet.

The patch disables interrupts when acquiring dc_task_lock spinlock.

	ocfs2_wake_downconvert_thread
	ocfs2_rw_unlock
	ocfs2_dio_end_io
	dio_complete
	.....
	bio_endio
	req_bio_endio
	....
	scsi_io_completion
	blk_done_softirq
	__do_softirq
	do_softirq
	irq_exit
	do_IRQ
	ocfs2_downconvert_thread
	[kthread]

Signed-off-by: default avatarSrinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: default avatarJoel Becker <jlbec@evilplan.org>
parent 16865b7c

fs/ocfs2/dlmglue.c

+19 −12
Original line number Diff line number Diff line
@@ -3932,6 +3932,8 @@ unqueue: 
static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,

					struct ocfs2_lock_res *lockres)

{

	unsigned long flags;



	assert_spin_locked(&lockres->l_lock);



	if (lockres->l_flags & OCFS2_LOCK_FREEING) {
@@ -3945,21 +3947,22 @@ static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb, 


	lockres_or_flags(lockres, OCFS2_LOCK_QUEUED);



	spin_lock(&osb->dc_task_lock);

	spin_lock_irqsave(&osb->dc_task_lock, flags);

	if (list_empty(&lockres->l_blocked_list)) {

		list_add_tail(&lockres->l_blocked_list,

			      &osb->blocked_lock_list);

		osb->blocked_lock_count++;

	}

	spin_unlock(&osb->dc_task_lock);

	spin_unlock_irqrestore(&osb->dc_task_lock, flags);

}



static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)

{

	unsigned long processed;

	unsigned long flags;

	struct ocfs2_lock_res *lockres;



	spin_lock(&osb->dc_task_lock);

	spin_lock_irqsave(&osb->dc_task_lock, flags);

	/* grab this early so we know to try again if a state change and

	 * wake happens part-way through our work  */

	osb->dc_work_sequence = osb->dc_wake_sequence;
@@ -3972,38 +3975,40 @@ static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb) 
				     struct ocfs2_lock_res, l_blocked_list);

		list_del_init(&lockres->l_blocked_list);

		osb->blocked_lock_count--;

		spin_unlock(&osb->dc_task_lock);

		spin_unlock_irqrestore(&osb->dc_task_lock, flags);



		BUG_ON(!processed);

		processed--;



		ocfs2_process_blocked_lock(osb, lockres);



		spin_lock(&osb->dc_task_lock);

		spin_lock_irqsave(&osb->dc_task_lock, flags);

	}

	spin_unlock(&osb->dc_task_lock);

	spin_unlock_irqrestore(&osb->dc_task_lock, flags);

}



static int ocfs2_downconvert_thread_lists_empty(struct ocfs2_super *osb)

{

	int empty = 0;

	unsigned long flags;



	spin_lock(&osb->dc_task_lock);

	spin_lock_irqsave(&osb->dc_task_lock, flags);

	if (list_empty(&osb->blocked_lock_list))

		empty = 1;



	spin_unlock(&osb->dc_task_lock);

	spin_unlock_irqrestore(&osb->dc_task_lock, flags);

	return empty;

}



static int ocfs2_downconvert_thread_should_wake(struct ocfs2_super *osb)

{

	int should_wake = 0;

	unsigned long flags;



	spin_lock(&osb->dc_task_lock);

	spin_lock_irqsave(&osb->dc_task_lock, flags);

	if (osb->dc_work_sequence != osb->dc_wake_sequence)

		should_wake = 1;

	spin_unlock(&osb->dc_task_lock);

	spin_unlock_irqrestore(&osb->dc_task_lock, flags);



	return should_wake;

}
@@ -4033,10 +4038,12 @@ static int ocfs2_downconvert_thread(void *arg) 


void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb)

{

	spin_lock(&osb->dc_task_lock);

	unsigned long flags;



	spin_lock_irqsave(&osb->dc_task_lock, flags);

	/* make sure the voting thread gets a swipe at whatever changes

	 * the caller may have made to the voting state */

	osb->dc_wake_sequence++;

	spin_unlock(&osb->dc_task_lock);

	spin_unlock_irqrestore(&osb->dc_task_lock, flags);

	wake_up(&osb->dc_event);

}

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