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-rw-r--r--fs/jbd2/transaction.c8
-rw-r--r--include/trace/events/jbd2.h21
2 files changed, 29 insertions, 0 deletions
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index a1920da2280..10f524c59ea 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -639,6 +639,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
int error;
char *frozen_buffer = NULL;
int need_copy = 0;
+ unsigned long start_lock, time_lock;
if (is_handle_aborted(handle))
return -EROFS;
@@ -654,9 +655,16 @@ repeat:
/* @@@ Need to check for errors here at some point. */
+ start_lock = jiffies;
lock_buffer(bh);
jbd_lock_bh_state(bh);
+ /* If it takes too long to lock the buffer, trace it */
+ time_lock = jbd2_time_diff(start_lock, jiffies);
+ if (time_lock > HZ/10)
+ trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
+ jiffies_to_msecs(time_lock));
+
/* We now hold the buffer lock so it is safe to query the buffer
* state. Is the buffer dirty?
*
diff --git a/include/trace/events/jbd2.h b/include/trace/events/jbd2.h
index 070df49e4a1..c1d1f3eb242 100644
--- a/include/trace/events/jbd2.h
+++ b/include/trace/events/jbd2.h
@@ -358,6 +358,27 @@ TRACE_EVENT(jbd2_write_superblock,
MINOR(__entry->dev), __entry->write_op)
);
+TRACE_EVENT(jbd2_lock_buffer_stall,
+
+ TP_PROTO(dev_t dev, unsigned long stall_ms),
+
+ TP_ARGS(dev, stall_ms),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field(unsigned long, stall_ms )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = dev;
+ __entry->stall_ms = stall_ms;
+ ),
+
+ TP_printk("dev %d,%d stall_ms %lu",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->stall_ms)
+);
+
#endif /* _TRACE_JBD2_H */
/* This part must be outside protection */