xfs: xfs_defer_capture should absorb remaining transaction reservation

When xfs_defer_capture extracts the deferred ops and transaction state
from a transaction, it should record the transaction reservation type
from the old transaction so that when we continue the dfops chain, we
still use the same reservation parameters.

Doing this means that the log item recovery functions get to determine
the transaction reservation instead of abusing tr_itruncate in yet
another part of xfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_defer.c

@@ -579,6 +579,9 @@ xfs_defer_ops_capture(
 	dfc->dfc_blkres = tp->t_blk_res - tp->t_blk_res_used;
 	dfc->dfc_rtxres = tp->t_rtx_res - tp->t_rtx_res_used;
 
+	/* Preserve the log reservation size. */
+	dfc->dfc_logres = tp->t_log_res;
+
 	return dfc;
 }
 

fs/xfs/libxfs/xfs_defer.h

@@ -79,6 +79,9 @@ struct xfs_defer_capture {
 	/* Block reservations for the data and rt devices. */
 	unsigned int		dfc_blkres;
 	unsigned int		dfc_rtxres;
+
+	/* Log reservation saved from the transaction. */
+	unsigned int		dfc_logres;
 };
 
 /*

fs/xfs/xfs_log_recover.c

@@ -2442,9 +2442,20 @@ xlog_finish_defer_ops(
 	int			error = 0;
 
 	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
-				dfc->dfc_blkres, dfc->dfc_rtxres,
-				XFS_TRANS_RESERVE, &tp);
+		struct xfs_trans_res	resv;
+
+		/*
+		 * Create a new transaction reservation from the captured
+		 * information.  Set logcount to 1 to force the new transaction
+		 * to regrant every roll so that we can make forward progress
+		 * in recovery no matter how full the log might be.
+		 */
+		resv.tr_logres = dfc->dfc_logres;
+		resv.tr_logcount = 1;
+		resv.tr_logflags = XFS_TRANS_PERM_LOG_RES;
+
+		error = xfs_trans_alloc(mp, &resv, dfc->dfc_blkres,
+				dfc->dfc_rtxres, XFS_TRANS_RESERVE, &tp);
 		if (error)
 			return error;