From: Josef Bacik <jwhiter@redhat.com>
Subject: [PATCH 5.1] dlm: fix debugfs ref counting problem
Date: Tue, 5 Jun 2007 17:58:01 -0400
Bugzilla: 242807
Message-Id: <20070605215800.GE28363@korben.rdu.redhat.com>
Changelog: [dlm] fix debugfs ref counting problem


Hello,

This patch is related to bz 242807.  This patch is from the upstream commit

http://git.kernel.org/?p=linux/kernel/git/steve/gfs2-2.6-nmw.git;a=commit;h=021d2ff3a08019260a1dc002793c92d6bf18afb6

and another smaller patch that corrects a problem with the original commit which
will be included upstream shortly.  This patch holds a reference on the rsb
while we are using it so it doesn't get freed out from underneath us while we
are trying to print it out.  Thank you,

Josef

Index: latest/fs/dlm/debug_fs.c
===================================================================
--- latest.orig/fs/dlm/debug_fs.c
+++ latest/fs/dlm/debug_fs.c
@@ -224,6 +224,9 @@ static int rsb_iter_next(struct rsb_iter
 			read_lock(&ls->ls_rsbtbl[i].lock);
 			if (!list_empty(&ls->ls_rsbtbl[i].list)) {
 				ri->next = ls->ls_rsbtbl[i].list.next;
+				ri->rsb = list_entry(ri->next, struct dlm_rsb,
+							res_hashchain);
+				dlm_hold_rsb(ri->rsb);
 				read_unlock(&ls->ls_rsbtbl[i].lock);
 				break;
 			}
@@ -234,6 +237,7 @@ static int rsb_iter_next(struct rsb_iter
 		if (ri->entry >= ls->ls_rsbtbl_size)
 			return 1;
 	} else {
+		struct dlm_rsb *old = ri->rsb;
 		i = ri->entry;
 		read_lock(&ls->ls_rsbtbl[i].lock);
 		ri->next = ri->next->next;
@@ -242,11 +246,14 @@ static int rsb_iter_next(struct rsb_iter
 			ri->next = NULL;
 			ri->entry++;
 			read_unlock(&ls->ls_rsbtbl[i].lock);
+			dlm_put_rsb(old);
 			goto top;
                 }
+		ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
+		dlm_hold_rsb(ri->rsb);
 		read_unlock(&ls->ls_rsbtbl[i].lock);
+		dlm_put_rsb(old);
 	}
-	ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
 
 	return 0;
 }