From: NeilBrown <neilb@suse.de>
Date: Mon, 9 Aug 2010 02:06:26 +0000 (+1000)
Subject: Add tracing for when we actually wait for writeback.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=840e111dff8d8384eeb1b67b80121d86ccd13dbc;p=LaFS.git

Add tracing for when we actually wait for writeback.

This helps track deadlock bugs, just like the similar code
in lafs_iolock_block.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/io.c b/io.c
index c7734aa..5fafb99 100644
--- a/io.c
+++ b/io.c
@@ -373,6 +373,11 @@ static void wait_writeback(struct block *b)
 {
 	if (test_bit(B_Writeback, &b->flags)) {
 		DEFINE_WAIT(wq);
+#ifdef DEBUG_IOLOCK
+		printk("writeback wait for %s:%d: %s\n",
+		       b->iolock_file, b->iolock_line,
+		       strblk(b));
+#endif
 		lafs_trigger_flush(b);
 		for (;;) {
 			prepare_to_wait(&block_wait, &wq, TASK_UNINTERRUPTIBLE);