From ebef1f2fb67c102f791c702386c6b8fe5bb8e9ae Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Tue, 7 Feb 2017 18:57:50 -0500
Subject: [PATCH] Fix iput() calls within a tx

As explicitly stated in section 2 of the 'Programming rules'
comments at the top of zfs_vnops.c.

  If you must call iput() within a tx then use zfs_iput_async().

Move iput() calls after dmu_tx_commit() / dmu_tx_abort when
possible.  When not possible convert the iput() calls to
zfs_iput_async().

Reviewed-by: Don Brady <don.brady@intel.com>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #5758
---
 module/zfs/zfs_vnops.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 384a37fea5..437a63a638 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -1602,13 +1602,13 @@ top:
 	error = dmu_tx_assign(tx, waited ? TXG_WAITED : TXG_NOWAIT);
 	if (error) {
 		zfs_dirent_unlock(dl);
-		iput(ip);
-		if (xzp)
-			iput(ZTOI(xzp));
 		if (error == ERESTART) {
 			waited = B_TRUE;
 			dmu_tx_wait(tx);
 			dmu_tx_abort(tx);
+			iput(ip);
+			if (xzp)
+				iput(ZTOI(xzp));
 			goto top;
 		}
 #ifdef HAVE_PN_UTILS
@@ -1616,6 +1616,9 @@ top:
 			pn_free(realnmp);
 #endif /* HAVE_PN_UTILS */
 		dmu_tx_abort(tx);
+		iput(ip);
+		if (xzp)
+			iput(ZTOI(xzp));
 		ZFS_EXIT(zsb);
 		return (error);
 	}
@@ -1944,14 +1947,15 @@ top:
 		rw_exit(&zp->z_parent_lock);
 		rw_exit(&zp->z_name_lock);
 		zfs_dirent_unlock(dl);
-		iput(ip);
 		if (error == ERESTART) {
 			waited = B_TRUE;
 			dmu_tx_wait(tx);
 			dmu_tx_abort(tx);
+			iput(ip);
 			goto top;
 		}
 		dmu_tx_abort(tx);
+		iput(ip);
 		ZFS_EXIT(zsb);
 		return (error);
 	}
@@ -3025,8 +3029,6 @@ out:
 		ASSERT(err2 == 0);
 	}
 
-	if (attrzp)
-		iput(ZTOI(attrzp));
 	if (aclp)
 		zfs_acl_free(aclp);
 
@@ -3037,11 +3039,15 @@ out:
 
 	if (err) {
 		dmu_tx_abort(tx);
+		if (attrzp)
+			iput(ZTOI(attrzp));
 		if (err == ERESTART)
 			goto top;
 	} else {
 		err2 = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
 		dmu_tx_commit(tx);
+		if (attrzp)
+			iput(ZTOI(attrzp));
 		zfs_inode_update(zp);
 	}
 
@@ -3074,7 +3080,7 @@ zfs_rename_unlock(zfs_zlock_t **zlpp)
 
 	while ((zl = *zlpp) != NULL) {
 		if (zl->zl_znode != NULL)
-			iput(ZTOI(zl->zl_znode));
+			zfs_iput_async(ZTOI(zl->zl_znode));
 		rw_exit(zl->zl_rwlock);
 		*zlpp = zl->zl_next;
 		kmem_free(zl, sizeof (*zl));
@@ -3411,16 +3417,19 @@ top:
 		if (sdzp == tdzp)
 			rw_exit(&sdzp->z_name_lock);
 
-		iput(ZTOI(szp));
-		if (tzp)
-			iput(ZTOI(tzp));
 		if (error == ERESTART) {
 			waited = B_TRUE;
 			dmu_tx_wait(tx);
 			dmu_tx_abort(tx);
+			iput(ZTOI(szp));
+			if (tzp)
+				iput(ZTOI(tzp));
 			goto top;
 		}
 		dmu_tx_abort(tx);
+		iput(ZTOI(szp));
+		if (tzp)
+			iput(ZTOI(tzp));
 		ZFS_EXIT(zsb);
 		return (error);
 	}