[PATCH v2 3/3] xfs: xfs_defer_capture should absorb remaining transaction reservation

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

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.

This avoids a potential failure vector by ensuring that we never ask for
more log reservation space than we would have asked for had the system
not gone down.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
v2: rebased on v2 of patch 1
---
 fs/xfs/libxfs/xfs_defer.c |    3 +++
 fs/xfs/libxfs/xfs_defer.h |    1 +
 fs/xfs/xfs_log_recover.c  |    4 ++--
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 8bd01952c955..b693d2c42c27 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -595,6 +595,9 @@ xfs_defer_capture(
 	dfc->dfc_tpflags = tp->t_flags & XFS_TRANS_LOWMODE;
 	dfc->dfc_blkres = tp->t_blk_res - tp->t_blk_res_used;
 	tp->t_blk_res = tp->t_blk_res_used;
+	dfc->dfc_tres.tr_logres = tp->t_log_res;
+	dfc->dfc_tres.tr_logcount = tp->t_log_count;
+	dfc->dfc_tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
 	xfs_defer_reset(tp);
 
 	/*
diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
index 59d126aeb31c..254d48e6e4dc 100644
--- a/fs/xfs/libxfs/xfs_defer.h
+++ b/fs/xfs/libxfs/xfs_defer.h
@@ -77,6 +77,7 @@ struct xfs_defer_capture {
 	struct list_head	dfc_dfops;
 	unsigned int		dfc_tpflags;
 	unsigned int		dfc_blkres;
+	struct xfs_trans_res	dfc_tres;
 };
 
 /*
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 777b60073ff7..ab9825ab14d5 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2504,8 +2504,8 @@ 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, 0,
-				0, XFS_TRANS_RESERVE, &tp);
+		error = xfs_trans_alloc(mp, &dfc->dfc_tres, 0, 0,
+				XFS_TRANS_RESERVE, &tp);
 		if (error)
 			return error;