ocfs2: do not lock/unlock() inode DLM lock

DLM does not cache locks.  So, blocking lock and unlock will only make
the performance worse where contention over the locks is high.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/dlmglue.c

@@ -2432,12 +2432,6 @@ bail:
  * done this we have to return AOP_TRUNCATED_PAGE so the aop method
  * that called us can bubble that back up into the VFS who will then
  * immediately retry the aop call.
- *
- * We do a blocking lock and immediate unlock before returning, though, so that
- * the lock has a great chance of being cached on this node by the time the VFS
- * calls back to retry the aop.    This has a potential to livelock as nodes
- * ping locks back and forth, but that's a risk we're willing to take to avoid
- * the lock inversion simply.
  */
 int ocfs2_inode_lock_with_page(struct inode *inode,
 			      struct buffer_head **ret_bh,
@@ -2449,8 +2443,6 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
 	ret = ocfs2_inode_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
 	if (ret == -EAGAIN) {
 		unlock_page(page);
-		if (ocfs2_inode_lock(inode, ret_bh, ex) == 0)
-			ocfs2_inode_unlock(inode, ex);
 		ret = AOP_TRUNCATED_PAGE;
 	}