lockdep: annotate journal_start()

On Fri, 2007-07-13 at 02:05 -0700, Andrew Morton wrote:

> Except lockdep doesn't know about journal_start(), which has ranking
> requirements similar to a semaphore.  
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fs/jbd/transaction.c

@@ -233,6 +233,8 @@ static int start_this_handle(journal_t *journal, handle_t *handle)
 	return ret;
 }
 
+static struct lock_class_key jbd_handle_key;
+
 /* Allocate a new handle.  This should probably be in a slab... */
 static handle_t *new_handle(int nblocks)
 {
@@ -243,6 +245,8 @@ static handle_t *new_handle(int nblocks)
 	handle->h_buffer_credits = nblocks;
 	handle->h_ref = 1;
 
+	lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
+
 	return handle;
 }
 
@@ -286,6 +290,9 @@ handle_t *journal_start(journal_t *journal, int nblocks)
 		current->journal_info = NULL;
 		handle = ERR_PTR(err);
 	}
+
+	lock_acquire(&handle->h_lockdep_map, 0, 0, 0, 2, _THIS_IP_);
+
 	return handle;
 }
 
@@ -1411,6 +1418,8 @@ int journal_stop(handle_t *handle)
 		spin_unlock(&journal->j_state_lock);
 	}
 
+	lock_release(&handle->h_lockdep_map, 1, _THIS_IP_);
+
 	jbd_free_handle(handle);
 	return err;
 }

include/linux/jbd.h

@@ -30,6 +30,7 @@
 #include <linux/bit_spinlock.h>
 #include <linux/mutex.h>
 #include <linux/timer.h>
+#include <linux/lockdep.h>
 
 #include <asm/semaphore.h>
 #endif
@@ -396,6 +397,10 @@ struct handle_s
 	unsigned int	h_sync:		1;	/* sync-on-close */
 	unsigned int	h_jdata:	1;	/* force data journaling */
 	unsigned int	h_aborted:	1;	/* fatal error on handle */
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	h_lockdep_map;
+#endif
 };