xfs: use transaction for intent recovery instead of raw dfops

Log intent recovery is the last user of an external (on-stack)
dfops. The pattern exists because the dfops is used to collect
additional deferred operations queued during the whole recovery
sequence. The dfops is finished with a new transaction after intent
recovery completes.

We already have a mechanism to create an empty, container-like
transaction to support the scrub infrastructure. We can reuse that
mechanism here to drop the final user of external dfops. This
facilitates folding dfops state (i.e., dop_low) into the
transaction, the elimination of now unused external dfops support
and also eliminates the only caller of __xfs_defer_cancel().

Replace the on-stack dfops with an empty transaction and pass it
around to the various helpers that queue and finish deferred
operations during intent recovery.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_bmap_item.c

@@ -375,9 +375,8 @@ xfs_bud_init(
  */
 int
 xfs_bui_recover(
-	struct xfs_mount		*mp,
-	struct xfs_bui_log_item		*buip,
-	struct xfs_defer_ops		*dfops)
+	struct xfs_trans		*parent_tp,
+	struct xfs_bui_log_item		*buip)
 {
 	int				error = 0;
 	unsigned int			bui_type;
@@ -393,6 +392,7 @@ xfs_bui_recover(
 	struct xfs_trans		*tp;
 	struct xfs_inode		*ip = NULL;
 	struct xfs_bmbt_irec		irec;
+	struct xfs_mount		*mp = parent_tp->t_mountp;
 
 	ASSERT(!test_bit(XFS_BUI_RECOVERED, &buip->bui_flags));
 
@@ -446,7 +446,7 @@ xfs_bui_recover(
 	 * finishes them on completion. Transfer current dfops state to this
 	 * transaction and transfer the result back before we return.
 	 */
-	xfs_defer_move(tp->t_dfops, dfops);
+	xfs_defer_move(tp->t_dfops, parent_tp->t_dfops);
 	budp = xfs_trans_get_bud(tp, buip);
 
 	/* Grab the inode. */
@@ -494,7 +494,7 @@ xfs_bui_recover(
 	}
 
 	set_bit(XFS_BUI_RECOVERED, &buip->bui_flags);
-	xfs_defer_move(dfops, tp->t_dfops);
+	xfs_defer_move(parent_tp->t_dfops, tp->t_dfops);
 	error = xfs_trans_commit(tp);
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	xfs_irele(ip);
@@ -502,7 +502,7 @@ xfs_bui_recover(
 	return error;
 
 err_inode:
-	xfs_defer_move(dfops, tp->t_dfops);
+	xfs_defer_move(parent_tp->t_dfops, tp->t_dfops);
 	xfs_trans_cancel(tp);
 	if (ip) {
 		xfs_iunlock(ip, XFS_ILOCK_EXCL);

fs/xfs/xfs_bmap_item.h

@@ -79,7 +79,6 @@ struct xfs_bud_log_item *xfs_bud_init(struct xfs_mount *,
 		struct xfs_bui_log_item *);
 void xfs_bui_item_free(struct xfs_bui_log_item *);
 void xfs_bui_release(struct xfs_bui_log_item *);
-int xfs_bui_recover(struct xfs_mount *mp, struct xfs_bui_log_item *buip,
-		struct xfs_defer_ops *dfops);
+int xfs_bui_recover(struct xfs_trans *parent_tp, struct xfs_bui_log_item *buip);
 
 #endif	/* __XFS_BMAP_ITEM_H__ */

fs/xfs/xfs_log_recover.c

@@ -4733,10 +4733,9 @@ xlog_recover_cancel_rui(
 /* Recover the CUI if necessary. */
 STATIC int
 xlog_recover_process_cui(
-	struct xfs_mount		*mp,
+	struct xfs_trans		*parent_tp,
 	struct xfs_ail			*ailp,
-	struct xfs_log_item		*lip,
-	struct xfs_defer_ops		*dfops)
+	struct xfs_log_item		*lip)
 {
 	struct xfs_cui_log_item		*cuip;
 	int				error;
@@ -4749,7 +4748,7 @@ xlog_recover_process_cui(
 		return 0;
 
 	spin_unlock(&ailp->ail_lock);
-	error = xfs_cui_recover(mp, cuip, dfops);
+	error = xfs_cui_recover(parent_tp, cuip);
 	spin_lock(&ailp->ail_lock);
 
 	return error;
@@ -4774,10 +4773,9 @@ xlog_recover_cancel_cui(
 /* Recover the BUI if necessary. */
 STATIC int
 xlog_recover_process_bui(
-	struct xfs_mount		*mp,
+	struct xfs_trans		*parent_tp,
 	struct xfs_ail			*ailp,
-	struct xfs_log_item		*lip,
-	struct xfs_defer_ops		*dfops)
+	struct xfs_log_item		*lip)
 {
 	struct xfs_bui_log_item		*buip;
 	int				error;
@@ -4790,7 +4788,7 @@ xlog_recover_process_bui(
 		return 0;
 
 	spin_unlock(&ailp->ail_lock);
-	error = xfs_bui_recover(mp, buip, dfops);
+	error = xfs_bui_recover(parent_tp, buip);
 	spin_lock(&ailp->ail_lock);
 
 	return error;
@@ -4829,9 +4827,9 @@ static inline bool xlog_item_is_intent(struct xfs_log_item *lip)
 /* Take all the collected deferred ops and finish them in order. */
 static int
 xlog_finish_defer_ops(
-	struct xfs_mount	*mp,
-	struct xfs_defer_ops	*dfops)
+	struct xfs_trans	*parent_tp)
 {
+	struct xfs_mount	*mp = parent_tp->t_mountp;
 	struct xfs_trans	*tp;
 	int64_t			freeblks;
 	uint			resblks;
@@ -4855,7 +4853,7 @@ xlog_finish_defer_ops(
 	if (error)
 		return error;
 	/* transfer all collected dfops to this transaction */
-	xfs_defer_move(tp->t_dfops, dfops);
+	xfs_defer_move(tp->t_dfops, parent_tp->t_dfops);
 
 	return xfs_trans_commit(tp);
 }
@@ -4880,22 +4878,34 @@ STATIC int
 xlog_recover_process_intents(
 	struct xlog		*log)
 {
-	struct xfs_defer_ops	dfops;
+	struct xfs_trans	*parent_tp;
 	struct xfs_ail_cursor	cur;
 	struct xfs_log_item	*lip;
 	struct xfs_ail		*ailp;
-	int			error = 0;
+	int			error;
 #if defined(DEBUG) || defined(XFS_WARN)
 	xfs_lsn_t		last_lsn;
 #endif
 
+	/*
+	 * The intent recovery handlers commit transactions to complete recovery
+	 * for individual intents, but any new deferred operations that are
+	 * queued during that process are held off until the very end. The
+	 * purpose of this transaction is to serve as a container for deferred
+	 * operations. Each intent recovery handler must transfer dfops here
+	 * before its local transaction commits, and we'll finish the entire
+	 * list below.
+	 */
+	error = xfs_trans_alloc_empty(log->l_mp, &parent_tp);
+	if (error)
+		return error;
+
 	ailp = log->l_ailp;
 	spin_lock(&ailp->ail_lock);
 	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
 #if defined(DEBUG) || defined(XFS_WARN)
 	last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
 #endif
-	xfs_defer_init(NULL, &dfops);
 	while (lip != NULL) {
 		/*
 		 * We're done when we see something other than an intent.
@@ -4930,12 +4940,10 @@ xlog_recover_process_intents(
 			error = xlog_recover_process_rui(log->l_mp, ailp, lip);
 			break;
 		case XFS_LI_CUI:
-			error = xlog_recover_process_cui(log->l_mp, ailp, lip,
-					&dfops);
+			error = xlog_recover_process_cui(parent_tp, ailp, lip);
 			break;
 		case XFS_LI_BUI:
-			error = xlog_recover_process_bui(log->l_mp, ailp, lip,
-					&dfops);
+			error = xlog_recover_process_bui(parent_tp, ailp, lip);
 			break;
 		}
 		if (error)
@@ -4945,10 +4953,9 @@ xlog_recover_process_intents(
 out:
 	xfs_trans_ail_cursor_done(&cur);
 	spin_unlock(&ailp->ail_lock);
-	if (error)
-		__xfs_defer_cancel(&dfops);
-	else
-		error = xlog_finish_defer_ops(log->l_mp, &dfops);
+	if (!error)
+		error = xlog_finish_defer_ops(parent_tp);
+	xfs_trans_cancel(parent_tp);
 
 	return error;
 }

fs/xfs/xfs_refcount_item.c

@@ -380,9 +380,8 @@ xfs_cud_init(
  */
 int
 xfs_cui_recover(
-	struct xfs_mount		*mp,
-	struct xfs_cui_log_item		*cuip,
-	struct xfs_defer_ops		*dfops)
+	struct xfs_trans		*parent_tp,
+	struct xfs_cui_log_item		*cuip)
 {
 	int				i;
 	int				error = 0;
@@ -398,6 +397,7 @@ xfs_cui_recover(
 	xfs_extlen_t			new_len;
 	struct xfs_bmbt_irec		irec;
 	bool				requeue_only = false;
+	struct xfs_mount		*mp = parent_tp->t_mountp;
 
 	ASSERT(!test_bit(XFS_CUI_RECOVERED, &cuip->cui_flags));
 
@@ -457,7 +457,7 @@ xfs_cui_recover(
 	 * finishes them on completion. Transfer current dfops state to this
 	 * transaction and transfer the result back before we return.
 	 */
-	xfs_defer_move(tp->t_dfops, dfops);
+	xfs_defer_move(tp->t_dfops, parent_tp->t_dfops);
 	cudp = xfs_trans_get_cud(tp, cuip);
 
 	for (i = 0; i < cuip->cui_format.cui_nextents; i++) {
@@ -522,13 +522,13 @@ xfs_cui_recover(
 
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
 	set_bit(XFS_CUI_RECOVERED, &cuip->cui_flags);
-	xfs_defer_move(dfops, tp->t_dfops);
+	xfs_defer_move(parent_tp->t_dfops, tp->t_dfops);
 	error = xfs_trans_commit(tp);
 	return error;
 
 abort_error:
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
-	xfs_defer_move(dfops, tp->t_dfops);
+	xfs_defer_move(parent_tp->t_dfops, tp->t_dfops);
 	xfs_trans_cancel(tp);
 	return error;
 }

fs/xfs/xfs_refcount_item.h

@@ -82,7 +82,6 @@ struct xfs_cud_log_item *xfs_cud_init(struct xfs_mount *,
 		struct xfs_cui_log_item *);
 void xfs_cui_item_free(struct xfs_cui_log_item *);
 void xfs_cui_release(struct xfs_cui_log_item *);
-int xfs_cui_recover(struct xfs_mount *mp, struct xfs_cui_log_item *cuip,
-		struct xfs_defer_ops *dfops);
+int xfs_cui_recover(struct xfs_trans *parent_tp, struct xfs_cui_log_item *cuip);
 
 #endif	/* __XFS_REFCOUNT_ITEM_H__ */