@@ -4006,9 +4006,13 @@ static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
osb->dc_work_sequence = osb->dc_wake_sequence;
processed = osb->blocked_lock_count;
- while (processed) {
- BUG_ON(list_empty(&osb->blocked_lock_list));
-
+ /*
+ * blocked lock processing in this loop might call iput which can
+ * remove items off osb->blocked_lock_list. Downconvert up to
+ * 'processed' number of locks, but stop short if we had some
+ * removed in ocfs2_mark_lockres_freeing when downconverting.
+ */
+ while (processed && !list_empty(&osb->blocked_lock_list)) {
lockres = list_entry(osb->blocked_lock_list.next,
struct ocfs2_lock_res, l_blocked_list);
list_del_init(&lockres->l_blocked_list);
This is a note to let you know that I have just added a patch titled ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt17. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From b3c6e774e81b63b8b1cc666a083ecd6bba6925cc Mon Sep 17 00:00:00 2001 From: Joseph Qi <joseph.qi@huawei.com> Date: Thu, 6 Aug 2015 15:46:23 -0700 Subject: ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() commit 209f7512d007980fd111a74a064d70a3656079cf upstream. The "BUG_ON(list_empty(&osb->blocked_lock_list))" in ocfs2_downconvert_thread_do_work can be triggered in the following case: ocfs2dc has firstly saved osb->blocked_lock_count to local varibale processed, and then processes the dentry lockres. During the dentry put, it calls iput and then deletes rw, inode and open lockres from blocked list in ocfs2_mark_lockres_freeing. And this causes the variable `processed' to not reflect the number of blocked lockres to be processed, which triggers the BUG. Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/ocfs2/dlmglue.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)