---

yaml
---
r: 376709
b: refs/heads/master
c: 7540617
h: refs/heads/master
i:
  376707: 62a686b
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ea929536a43226a01d1a73ac8b14d52e81163bd4
+refs/heads/master: 75406170751b4de88a01f73dda56efa617ddd5d7

trunk/fs/xfs/xfs_log_recover.c

@@ -1599,10 +1599,43 @@ xlog_recover_add_to_trans(
 }
 
 /*
- * Sort the log items in the transaction. Cancelled buffers need
- * to be put first so they are processed before any items that might
- * modify the buffers. If they are cancelled, then the modifications
- * don't need to be replayed.
+ * Sort the log items in the transaction.
+ *
+ * The ordering constraints are defined by the inode allocation and unlink
+ * behaviour. The rules are:
+ *
+ *	1. Every item is only logged once in a given transaction. Hence it
+ *	   represents the last logged state of the item. Hence ordering is
+ *	   dependent on the order in which operations need to be performed so
+ *	   required initial conditions are always met.
+ *
+ *	2. Cancelled buffers are recorded in pass 1 in a separate table and
+ *	   there's nothing to replay from them so we can simply cull them
+ *	   from the transaction. However, we can't do that until after we've
+ *	   replayed all the other items because they may be dependent on the
+ *	   cancelled buffer and replaying the cancelled buffer can remove it
+ *	   form the cancelled buffer table. Hence they have tobe done last.
+ *
+ *	3. Inode allocation buffers must be replayed before inode items that
+ *	   read the buffer and replay changes into it.
+ *
+ *	4. Inode unlink buffers must be replayed after inode items are replayed.
+ *	   This ensures that inodes are completely flushed to the inode buffer
+ *	   in a "free" state before we remove the unlinked inode list pointer.
+ *
+ * Hence the ordering needs to be inode allocation buffers first, inode items
+ * second, inode unlink buffers third and cancelled buffers last.
+ *
+ * But there's a problem with that - we can't tell an inode allocation buffer
+ * apart from a regular buffer, so we can't separate them. We can, however,
+ * tell an inode unlink buffer from the others, and so we can separate them out
+ * from all the other buffers and move them to last.
+ *
+ * Hence, 4 lists, in order from head to tail:
+ * 	- buffer_list for all buffers except cancelled/inode unlink buffers
+ * 	- item_list for all non-buffer items
+ * 	- inode_buffer_list for inode unlink buffers
+ * 	- cancel_list for the cancelled buffers
  */
 STATIC int
 xlog_recover_reorder_trans(
@@ -1612,27 +1645,37 @@ xlog_recover_reorder_trans(
 {
 	xlog_recover_item_t	*item, *n;
 	LIST_HEAD(sort_list);
+	LIST_HEAD(cancel_list);
+	LIST_HEAD(buffer_list);
+	LIST_HEAD(inode_buffer_list);
+	LIST_HEAD(inode_list);
 
 	list_splice_init(&trans->r_itemq, &sort_list);
 	list_for_each_entry_safe(item, n, &sort_list, ri_list) {
 		xfs_buf_log_format_t	*buf_f = item->ri_buf[0].i_addr;
 
 		switch (ITEM_TYPE(item)) {
 		case XFS_LI_BUF:
-			if (!(buf_f->blf_flags & XFS_BLF_CANCEL)) {
+			if (buf_f->blf_flags & XFS_BLF_CANCEL) {
 				trace_xfs_log_recover_item_reorder_head(log,
 							trans, item, pass);
-				list_move(&item->ri_list, &trans->r_itemq);
+				list_move(&item->ri_list, &cancel_list);
 				break;
 			}
+			if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
+				list_move(&item->ri_list, &inode_buffer_list);
+				break;
+			}
+			list_move_tail(&item->ri_list, &buffer_list);
+			break;
 		case XFS_LI_INODE:
 		case XFS_LI_DQUOT:
 		case XFS_LI_QUOTAOFF:
 		case XFS_LI_EFD:
 		case XFS_LI_EFI:
 			trace_xfs_log_recover_item_reorder_tail(log,
 							trans, item, pass);
-			list_move_tail(&item->ri_list, &trans->r_itemq);
+			list_move_tail(&item->ri_list, &inode_list);
 			break;
 		default:
 			xfs_warn(log->l_mp,
@@ -1643,6 +1686,14 @@ xlog_recover_reorder_trans(
 		}
 	}
 	ASSERT(list_empty(&sort_list));
+	if (!list_empty(&buffer_list))
+		list_splice(&buffer_list, &trans->r_itemq);
+	if (!list_empty(&inode_list))
+		list_splice_tail(&inode_list, &trans->r_itemq);
+	if (!list_empty(&inode_buffer_list))
+		list_splice_tail(&inode_buffer_list, &trans->r_itemq);
+	if (!list_empty(&cancel_list))
+		list_splice_tail(&cancel_list, &trans->r_itemq);
 	return 0;
 }