From 2f05c7ff5759f89a12f6e94afad53ac6fd536043 Mon Sep 17 00:00:00 2001
From: Venkatesh Srinivas <me@endeavour.zapto.org>
Date: Fri, 13 Apr 2012 17:46:42 -0700
Subject: [PATCH] kernel -- Per-mount threaded syncer infrastructure.

Do not shut down syncer thread when unmount fails.

Reminded-by: dillon@
---
 sys/kern/vfs_sync.c   | 13 ++++++++++---
 sys/kern/vfs_vfsops.c | 12 +++++++++---
 sys/sys/vnode.h       |  3 ++-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/sys/kern/vfs_sync.c b/sys/kern/vfs_sync.c
index 4591043c0f..59d2f253a9 100644
--- a/sys/kern/vfs_sync.c
+++ b/sys/kern/vfs_sync.c
@@ -265,15 +265,21 @@ vn_syncer_thr_create(struct mount *mp)
 			    "syncer%d", ++syncalloc);
 }
 
+void *
+vn_syncer_thr_getctx(struct mount *mp)
+{
+	return (mp->mnt_syncer_ctx);
+}
+
 /*
  * Stop per-filesystem syncer process
  */
 void
-vn_syncer_thr_stop(struct mount *mp)
+vn_syncer_thr_stop(void *ctxp)
 {
 	struct syncer_ctx *ctx;
 
-	ctx = mp->mnt_syncer_ctx;
+	ctx = ctxp;
 
 	lwkt_gettoken(&ctx->sc_token);
 
@@ -285,7 +291,6 @@ vn_syncer_thr_stop(struct mount *mp)
 	while ((ctx->sc_flags & SC_FLAG_DONE) == 0) 
 		tsleep(&ctx->sc_flags, 0, "syncexit", hz);
 
-	mp->mnt_syncer_ctx = NULL;
 	lwkt_reltoken(&ctx->sc_token);
 	
 	kfree(ctx->syncer_workitem_pending, M_DEVBUF);
@@ -309,6 +314,8 @@ syncer_thread(void *_ctx)
 	int sc_flags;
 	int vnodes_synced = 0;
 
+	atomic_clear_int(&curthread->td_flags, TDF_VERBOSE);
+
 	/*
 	 * syncer0 runs till system shutdown; per-filesystem syncers are
 	 * terminated on filesystem unmount
diff --git a/sys/kern/vfs_vfsops.c b/sys/kern/vfs_vfsops.c
index f5b0937d1f..9d52a3e605 100644
--- a/sys/kern/vfs_vfsops.c
+++ b/sys/kern/vfs_vfsops.c
@@ -130,13 +130,19 @@ vfs_unmount(struct mount *mp, int mntflags)
 {
 	VFS_MPLOCK_DECLARE;
 	int error;
+	int flags;
+	void *ctx;
 
 	VFS_MPLOCK1(mp);
-	if (mp->mnt_kern_flag & MNTK_THR_SYNC)
-		vn_syncer_thr_stop(mp);
 	error = (mp->mnt_op->vfs_acdone)(mp); 
-	if (error == 0)
+	if (error == 0) {
+		flags = mp->mnt_kern_flag;
+		ctx = vn_syncer_thr_getctx(mp);
 		error = (mp->mnt_op->vfs_unmount)(mp, mntflags);
+	}
+	if (error == 0 &&
+	    flags & MNTK_THR_SYNC)
+		vn_syncer_thr_stop(ctx);
 	VFS_MPUNLOCK(mp);
 	return (error);
 }
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index b829510c9c..f699f7332b 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -551,7 +551,8 @@ void	mount_init(struct mount *mp);
 void	vn_syncer_add(struct vnode *, int);
 void	vn_syncer_remove(struct vnode *);
 void	vn_syncer_thr_create(struct mount *);
-void	vn_syncer_thr_stop(struct mount *);
+void	*vn_syncer_thr_getctx(struct mount *);
+void	vn_syncer_thr_stop(void *);
 
 void	vnlru_proc_wait(void);
 
-- 
2.41.0