[RFC v5 PATCH 4/9] xfs: automatic relogging item management

[Brian Foster <bfoster@redhat.com>]

As implemented by the previous patch, relogging can be enabled on
any item via a relog enabled transaction (which holds a reference to
an active relog ticket). Add a couple log item flags to track relog
state of an arbitrary log item. The item holds a reference to the
global relog ticket when relogging is enabled and releases the
reference when relogging is disabled.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/xfs_trace.h      |  2 ++
 fs/xfs/xfs_trans.c      | 36 ++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_trans.h      |  6 +++++-
 fs/xfs/xfs_trans_priv.h |  2 ++
 4 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index a86be7f807ee..a066617ec54d 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1063,6 +1063,8 @@ DEFINE_LOG_ITEM_EVENT(xfs_ail_push);
 DEFINE_LOG_ITEM_EVENT(xfs_ail_pinned);
 DEFINE_LOG_ITEM_EVENT(xfs_ail_locked);
 DEFINE_LOG_ITEM_EVENT(xfs_ail_flushing);
+DEFINE_LOG_ITEM_EVENT(xfs_relog_item);
+DEFINE_LOG_ITEM_EVENT(xfs_relog_item_cancel);
 
 DECLARE_EVENT_CLASS(xfs_ail_class,
 	TP_PROTO(struct xfs_log_item *lip, xfs_lsn_t old_lsn, xfs_lsn_t new_lsn),
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 8ac05ed8deda..f7f2411ead4e 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -778,6 +778,41 @@ xfs_trans_del_item(
 	list_del_init(&lip->li_trans);
 }
 
+void
+xfs_trans_relog_item(
+	struct xfs_log_item	*lip)
+{
+	if (!test_and_set_bit(XFS_LI_RELOG, &lip->li_flags)) {
+		xfs_trans_ail_relog_get(lip->li_mountp);
+		trace_xfs_relog_item(lip);
+	}
+}
+
+void
+xfs_trans_relog_item_cancel(
+	struct xfs_log_item	*lip,
+	bool			drain) /* wait for relogging to cease */
+{
+	struct xfs_mount	*mp = lip->li_mountp;
+
+	if (!test_and_clear_bit(XFS_LI_RELOG, &lip->li_flags))
+		return;
+	xfs_trans_ail_relog_put(lip->li_mountp);
+	trace_xfs_relog_item_cancel(lip);
+
+	if (!drain)
+		return;
+
+	/*
+	 * Some operations might require relog activity to cease before they can
+	 * proceed. For example, an operation must wait before including a
+	 * non-lockable log item (i.e. intent) in another transaction.
+	 */
+	while (wait_on_bit_timeout(&lip->li_flags, XFS_LI_RELOGGED,
+				   TASK_UNINTERRUPTIBLE, HZ))
+		xfs_log_force(mp, XFS_LOG_SYNC);
+}
+
 /* Detach and unlock all of the items in a transaction */
 static void
 xfs_trans_free_items(
@@ -863,6 +898,7 @@ xfs_trans_committed_bulk(
 
 		if (aborted)
 			set_bit(XFS_LI_ABORTED, &lip->li_flags);
+		clear_and_wake_up_bit(XFS_LI_RELOGGED, &lip->li_flags);
 
 		if (lip->li_ops->flags & XFS_ITEM_RELEASE_WHEN_COMMITTED) {
 			lip->li_ops->iop_release(lip);
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index a032989943bd..fc4c25b6eee4 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -59,12 +59,16 @@ struct xfs_log_item {
 #define	XFS_LI_ABORTED	1
 #define	XFS_LI_FAILED	2
 #define	XFS_LI_DIRTY	3	/* log item dirty in transaction */
+#define	XFS_LI_RELOG	4	/* automatically relog item */
+#define	XFS_LI_RELOGGED	5	/* item relogged (not committed) */
 
 #define XFS_LI_FLAGS \
 	{ (1 << XFS_LI_IN_AIL),		"IN_AIL" }, \
 	{ (1 << XFS_LI_ABORTED),	"ABORTED" }, \
 	{ (1 << XFS_LI_FAILED),		"FAILED" }, \
-	{ (1 << XFS_LI_DIRTY),		"DIRTY" }
+	{ (1 << XFS_LI_DIRTY),		"DIRTY" }, \
+	{ (1 << XFS_LI_RELOG),		"RELOG" }, \
+	{ (1 << XFS_LI_RELOGGED),	"RELOGGED" }
 
 struct xfs_item_ops {
 	unsigned flags;
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index 839df6559b9f..d1edec1cb8ad 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/fs/xfs/xfs_trans_priv.h
@@ -16,6 +16,8 @@ struct xfs_log_vec;
 void	xfs_trans_init(struct xfs_mount *);
 void	xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
 void	xfs_trans_del_item(struct xfs_log_item *);
+void	xfs_trans_relog_item(struct xfs_log_item *);
+void	xfs_trans_relog_item_cancel(struct xfs_log_item *, bool);
 void	xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
 
 void	xfs_trans_committed_bulk(struct xfs_ail *ailp, struct xfs_log_vec *lv,
-- 
2.21.1