From 5aaeed5c617553c4cec6328c1f4c19079a5a495a Mon Sep 17 00:00:00 2001
From: Sanjeev Bagewadi <Sanjeev.Bagewadi@Sun.COM>
Date: Tue, 29 Jun 2010 15:11:58 +0530
Subject: [PATCH] 6937998 txg_wait_synced() is called when unmounting zfs
 snapshots

---
 usr/src/uts/common/fs/zfs/dmu_objset.c     | 9 +++++++++
 usr/src/uts/common/fs/zfs/sys/dmu_objset.h | 1 +
 usr/src/uts/common/fs/zfs/zfs_vfsops.c     | 5 ++---
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/usr/src/uts/common/fs/zfs/dmu_objset.c b/usr/src/uts/common/fs/zfs/dmu_objset.c
index 5554bda8f9b0..f5ef5d9d01c8 100644
--- a/usr/src/uts/common/fs/zfs/dmu_objset.c
+++ b/usr/src/uts/common/fs/zfs/dmu_objset.c
@@ -1116,6 +1116,15 @@ dmu_objset_is_dirty(objset_t *os, uint64_t txg)
 	    !list_is_empty(&os->os_free_dnodes[txg & TXG_MASK]));
 }
 
+boolean_t
+dmu_objset_is_dirty_anywhere(objset_t *os)
+{
+	for (int t = 0; t < TXG_SIZE; t++)
+		if (dmu_objset_is_dirty(os, t))
+			return (B_TRUE);
+	return (B_FALSE);
+}
+
 static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
 
 void
diff --git a/usr/src/uts/common/fs/zfs/sys/dmu_objset.h b/usr/src/uts/common/fs/zfs/sys/dmu_objset.h
index 12d5c4ddd497..e516c41115a5 100644
--- a/usr/src/uts/common/fs/zfs/sys/dmu_objset.h
+++ b/usr/src/uts/common/fs/zfs/sys/dmu_objset.h
@@ -161,6 +161,7 @@ timestruc_t dmu_objset_snap_cmtime(objset_t *os);
 /* called from dsl */
 void dmu_objset_sync(objset_t *os, zio_t *zio, dmu_tx_t *tx);
 boolean_t dmu_objset_is_dirty(objset_t *os, uint64_t txg);
+boolean_t dmu_objset_is_dirty_anywhere(objset_t *os);
 objset_t *dmu_objset_create_impl(spa_t *spa, struct dsl_dataset *ds,
     blkptr_t *bp, dmu_objset_type_t type, dmu_tx_t *tx);
 int dmu_objset_open_impl(spa_t *spa, struct dsl_dataset *ds, blkptr_t *bp,
diff --git a/usr/src/uts/common/fs/zfs/zfs_vfsops.c b/usr/src/uts/common/fs/zfs/zfs_vfsops.c
index 1731889f83b9..46aa3260e758 100644
--- a/usr/src/uts/common/fs/zfs/zfs_vfsops.c
+++ b/usr/src/uts/common/fs/zfs/zfs_vfsops.c
@@ -1812,10 +1812,9 @@ zfsvfs_teardown(zfsvfs_t *zfsvfs, boolean_t unmounting)
 	/*
 	 * Evict cached data
 	 */
-	if (dmu_objset_evict_dbufs(zfsvfs->z_os)) {
+	if (dmu_objset_is_dirty_anywhere(zfsvfs->z_os))
 		txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), 0);
-		(void) dmu_objset_evict_dbufs(zfsvfs->z_os);
-	}
+	(void) dmu_objset_evict_dbufs(zfsvfs->z_os);
 
 	return (0);
 }