btrfs: Add trace for btrfs_workqueue alloc/destroy

Since most of the btrfs_workqueue is printed as pointer address,
for easier analysis, add trace for btrfs_workqueue alloc/destroy.
So it is possible to determine the workqueue that a given work belongs
to(by comparing the wq pointer address with alloc trace event).

Signed-off-by: Qu Wenruo <quenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 66532b8f0f7c..ecb5832c0967 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -56,7 +56,8 @@ struct btrfs_workqueue {
 };
 
 static inline struct __btrfs_workqueue
-*__btrfs_alloc_workqueue(char *name, int flags, int max_active, int thresh)
+*__btrfs_alloc_workqueue(const char *name, int flags, int max_active,
+                         int thresh)
 {
         struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 
@@ -92,13 +93,14 @@ static inline struct __btrfs_workqueue
         INIT_LIST_HEAD(&ret->ordered_list);
         spin_lock_init(&ret->list_lock);
         spin_lock_init(&ret->thres_lock);
+        trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
         return ret;
 }
 
 static inline void
 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
 
-struct btrfs_workqueue *btrfs_alloc_workqueue(char *name,
+struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
                                               int flags,
                                               int max_active,
                                               int thresh)
@@ -305,6 +307,7 @@ static inline void
 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
 {
         destroy_workqueue(wq->normal_wq);
+        trace_btrfs_workqueue_destroy(wq);
         kfree(wq);
 }