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authorJoseph Qi <joseph.qi@huawei.com>2015-08-06 15:46:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-07 04:39:40 +0300
commit209f7512d007980fd111a74a064d70a3656079cf (patch)
tree0b12e03001248c15a79286d66caa295c33d2dbd7
parent4248b0da460839e30eaaad78992b9a1dd3e63e21 (diff)
downloadlinux-stericsson-209f7512d007980fd111a74a064d70a3656079cf.tar.gz
ocfs2: fix BUG in ocfs2_downconvert_thread_do_work()
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> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/ocfs2/dlmglue.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 8b23aa2f52dd..23157e40dd74 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -4025,9 +4025,13 @@ 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);