xfs: create a polled function to force inode inactivationdeferred-inactivation_2019-08-16

Create a polled version of xfs_inactive_force so that we can force
inactivation while holding a lock (usually the umount lock) without
tripping over the softlockup timer.  This is for callers that hold vfs
locks while calling inactivation, which is currently unmount, iunlink
processing during mount, and rw->ro remount.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 13e7b806d9a1..168c3c71887c 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -24,6 +24,7 @@
 #include "xfs_reflink.h"
 
 #include <linux/iversion.h>
+#include <linux/nmi.h>
 
 static void xfs_perag_set_inactive_tag(struct xfs_perag *pag);
 static void xfs_perag_clear_inactive_tag(struct xfs_perag *pag);
@@ -2139,6 +2140,8 @@ xfs_inactive_inodes_pag(
 	if (inctx.kick_reclaim)
 		xfs_reclaim_work_queue(pag->pag_mount);
 
+	wake_up(&pag->pag_mount->m_inactive_wait);
+
 	return error;
 }
 
@@ -2162,6 +2165,8 @@ xfs_inactive_inodes(
 	if (inctx.kick_reclaim)
 		xfs_reclaim_work_queue(mp);
 
+	wake_up(&mp->m_inactive_wait);
+
 	return error;
 }
 
@@ -2273,3 +2278,40 @@ xfs_inactive_schedule_work(
 		xfs_perag_put(pag);
 	}
 }
+
+/* Return true if there are inodes still being inactivated. */
+static bool
+xfs_inactive_pending(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		ag = 0;
+	bool			ret = false;
+
+	while (!ret && (pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
+		ag = pag->pag_agno + 1;
+		spin_lock(&pag->pag_ici_lock);
+		if (pag->pag_ici_inactive)
+			ret = true;
+		spin_unlock(&pag->pag_ici_lock);
+		xfs_perag_put(pag);
+	}
+
+	return ret;
+}
+
+/*
+ * Flush all pending inactivation work and poll until finished.  This function
+ * is for callers that must flush with vfs locks held, such as unmount,
+ * remount, and iunlinks processing during mount.
+ */
+void
+xfs_inactive_force_poll(
+	struct xfs_mount	*mp)
+{
+	xfs_inactive_schedule_work(mp, 0);
+	while (wait_event_timeout(mp->m_inactive_wait,
+			xfs_inactive_pending(mp) == false, HZ / 10) == 0) {
+		touch_softlockup_watchdog();
+	}
+}