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authorjiangyiwen <jiangyiwen@huawei.com>2016-03-25 14:21:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-25 16:37:42 -0700
commit35ddf78e41852cbbd216948425a091ab9815678f (patch)
tree34d4ccd01c6a3bee717c545ecc0199d8c4213fd3 /fs/ocfs2/ocfs2.h
parentbe12b299a83fc807bbaccd2bcb8ec50cbb0cb55c (diff)
ocfs2: fix occurring deadlock by changing ocfs2_wq from global to local
This patch fixes a deadlock, as follows: Node 1 Node 2 Node 3 1)volume a and b are only mount vol a only mount vol b mounted 2) start to mount b start to mount a 3) check hb of Node 3 check hb of Node 2 in vol a, qs_holds++ in vol b, qs_holds++ 4) -------------------- all nodes' network down -------------------- 5) progress of mount b the same situation as failed, and then call Node 2 ocfs2_dismount_volume. but the process is hung, since there is a work in ocfs2_wq cannot beo completed. This work is about vol a, because ocfs2_wq is global wq. BTW, this work which is scheduled in ocfs2_wq is ocfs2_orphan_scan_work, and the context in this work needs to take inode lock of orphan_dir, because lockres owner are Node 1 and all nodes' nework has been down at the same time, so it can't get the inode lock. 6) Why can't this node be fenced when network disconnected? Because the process of mount is hung what caused qs_holds is not equal 0. Because all works in the ocfs2_wq are relative to the super block. The solution is to change the ocfs2_wq from global to local. In other words, move it into struct ocfs2_super. Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com> Reviewed-by: Joseph Qi <joseph.qi@huawei.com> Cc: Xue jiufei <xuejiufei@huawei.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Cc: Cc: Junxiao Bi <junxiao.bi@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2/ocfs2.h')
-rw-r--r--fs/ocfs2/ocfs2.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 7a0126267847..6cf6538a0651 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -464,6 +464,14 @@ struct ocfs2_super
struct ocfs2_refcount_tree *osb_ref_tree_lru;
struct mutex system_file_mutex;
+
+ /*
+ * OCFS2 needs to schedule several different types of work which
+ * require cluster locking, disk I/O, recovery waits, etc. Since these
+ * types of work tend to be heavy we avoid using the kernel events
+ * workqueue and schedule on our own.
+ */
+ struct workqueue_struct *ocfs2_wq;
};
#define OCFS2_SB(sb) ((struct ocfs2_super *)(sb)->s_fs_info)