ocfs2: Add ->set_lvb callback in dlmglue

This allows a lock type to set the value block before downconvert.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 9e8ed60..faa6f57 100644 (file)
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -130,6 +130,17 @@ struct ocfs2_lock_res_ops {
         */
        int (*check_downconvert)(struct ocfs2_lock_res *, int);
 
+       /*
+        * Allows a lock type to populate the lock value block. This
+        * is called on downconvert, and when we drop a lock.
+        *
+        * Locks that want to use this should set LOCK_TYPE_USES_LVB
+        * in the flags field.
+        *
+        * Called with the lockres spinlock held.
+        */
+       void (*set_lvb)(struct ocfs2_lock_res *);
+
        /*
         * LOCK_TYPE_* flags which describe the specific requirements
         * of a lock type. Descriptions of each individual flag follow.
@@ -148,7 +159,8 @@ struct ocfs2_lock_res_ops {
 #define LOCK_TYPE_REQUIRES_REFRESH 0x1
 
 /*
- * Indicate that a lock type makes use of the lock value block.
+ * Indicate that a lock type makes use of the lock value block. The
+ * ->set_lvb lock type callback must be defined.
  */
 #define LOCK_TYPE_USES_LVB             0x2
 
@@ -2629,6 +2641,7 @@ static int ocfs2_generic_unblock_lock(struct ocfs2_super *osb,
        int blocking;
        int new_level;
        int ret = 0;
+       int set_lvb = 0;
 
        mlog_entry_void();
 
@@ -2703,9 +2716,23 @@ recheck:
 downconvert:
        ctl->requeue = 0;
 
+       if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
+               if (lockres->l_level == LKM_EXMODE)
+                       set_lvb = 1;
+
+               /*
+                * We only set the lvb if the lock has been fully
+                * refreshed - otherwise we risk setting stale
+                * data. Otherwise, there's no need to actually clear
+                * out the lvb here as it's value is still valid.
+                */
+               if (set_lvb && !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
+                       lockres->l_ops->set_lvb(lockres);
+       }
+
        ocfs2_prepare_downconvert(lockres, new_level);
        spin_unlock_irqrestore(&lockres->l_lock, flags);
-       ret = ocfs2_downconvert_lock(osb, lockres, new_level, 0);
+       ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb);
 leave:
        mlog_exit(ret);
        return ret;