ocfs2: Fix deadlock on umount

In commit ea455f8ab68338ba69f5d3362b342c115bea8e13, we moved the dentry lock
put process into ocfs2_wq. This causes problems during umount because ocfs2_wq
can drop references to inodes while they are being invalidated by
invalidate_inodes() causing all sorts of nasty things (invalidate_inodes()
ending in an infinite loop, "Busy inodes after umount" messages etc.).

We fix the problem by stopping ocfs2_wq from doing any further releasing of
inode references on the superblock being unmounted, wait until it finishes
the current round of releasing and finally cleaning up all the references in
dentry_lock_list from ocfs2_put_super().

The issue was tracked down by Tao Ma <tao.ma@oracle.com>.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 18 insertions, 4 deletions

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index c9345ebb8493..39e1d5a39505 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -224,10 +224,12 @@ enum ocfs2_mount_options
         OCFS2_MOUNT_GRPQUOTA = 1 << 10, /* We support group quotas */
 };
 
-#define OCFS2_OSB_SOFT_RO       0x0001
-#define OCFS2_OSB_HARD_RO       0x0002
-#define OCFS2_OSB_ERROR_FS      0x0004
-#define OCFS2_DEFAULT_ATIME_QUANTUM     60
+#define OCFS2_OSB_SOFT_RO                       0x0001
+#define OCFS2_OSB_HARD_RO                       0x0002
+#define OCFS2_OSB_ERROR_FS                      0x0004
+#define OCFS2_OSB_DROP_DENTRY_LOCK_IMMED        0x0008
+
+#define OCFS2_DEFAULT_ATIME_QUANTUM             60
 
 struct ocfs2_journal;
 struct ocfs2_slot_info;
@@ -490,6 +492,18 @@ static inline void ocfs2_set_osb_flag(struct ocfs2_super *osb,
         spin_unlock(&osb->osb_lock);
 }
 
+
+static inline unsigned long  ocfs2_test_osb_flag(struct ocfs2_super *osb,
+                                                 unsigned long flag)
+{
+        unsigned long ret;
+
+        spin_lock(&osb->osb_lock);
+        ret = osb->osb_flags & flag;
+        spin_unlock(&osb->osb_lock);
+        return ret;
+}
+
 static inline void ocfs2_set_ro_flag(struct ocfs2_super *osb,
                                      int hard)
 {