xfs: fix EFI transaction cancellation.

XFS_EFI_CANCELED has not been set in the code base since
xfs_efi_cancel() was removed back in 2006 by commit
065d312 ("[XFS] Remove unused
iop_abort log item operation), and even then xfs_efi_cancel() was
never called. I haven't tracked it back further than that (beyond
git history), but it indicates that the handling of EFIs in
cancelled transactions has been broken for a long time.

Basically, when we get an IOP_UNPIN(lip, 1); call from
xfs_trans_uncommit() (i.e. remove == 1), if we don't free the log
item descriptor we leak it. Fix the behviour to be correct and kill
the XFS_EFI_CANCELED flag.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_extfree_item.c

@@ -99,10 +99,11 @@ xfs_efi_item_pin(
 }
 
 /*
- * While EFIs cannot really be pinned, the unpin operation is the
- * last place at which the EFI is manipulated during a transaction.
- * Here we coordinate with xfs_efi_cancel() to determine who gets to
- * free the EFI.
+ * While EFIs cannot really be pinned, the unpin operation is the last place at
+ * which the EFI is manipulated during a transaction.  If we are being asked to
+ * remove the EFI it's because the transaction has been cancelled and by
+ * definition that means the EFI cannot be in the AIL so remove it from the
+ * transaction and free it.
  */
 STATIC void
 xfs_efi_item_unpin(
@@ -113,17 +114,14 @@ xfs_efi_item_unpin(
 	struct xfs_ail		*ailp = lip->li_ailp;
 
 	spin_lock(&ailp->xa_lock);
-	if (efip->efi_flags & XFS_EFI_CANCELED) {
-		if (remove)
-			xfs_trans_del_item(lip);
-
-		/* xfs_trans_ail_delete() drops the AIL lock. */
-		xfs_trans_ail_delete(ailp, lip);
+	if (remove) {
+		ASSERT(!(lip->li_flags & XFS_LI_IN_AIL));
+		xfs_trans_del_item(lip);
 		xfs_efi_item_free(efip);
 	} else {
 		efip->efi_flags |= XFS_EFI_COMMITTED;
-		spin_unlock(&ailp->xa_lock);
 	}
+	spin_unlock(&ailp->xa_lock);
 }
 
 /*

fs/xfs/xfs_extfree_item.h

@@ -115,7 +115,6 @@ typedef struct xfs_efd_log_format_64 {
  */
 #define	XFS_EFI_RECOVERED	0x1
 #define	XFS_EFI_COMMITTED	0x2
-#define	XFS_EFI_CANCELED	0x4
 
 /*
  * This is the "extent free intention" log item.  It is used