svn commit: r287662 - stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Andriy Gapon]

Author: avg
Date: Fri Sep 11 12:43:31 2015
New Revision: 287662
URL: https://svnweb.freebsd.org/changeset/base/287662

Log:
  MFC r285021: zfs_mount(MS_REMOUNT): protect zfs_(un)register_callbacks calls

Modified:
  stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/cddl/contrib/opensolaris/   (props changed)

Modified: stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
==============================================================================
--- stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c	Fri Sep 11 12:41:59 2015	(r287661)
+++ stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c	Fri Sep 11 12:43:31 2015	(r287662)
@@ -1708,9 +1708,19 @@ zfs_mount(vfs_t *vfsp)
 	 * according to those options set in the current VFS options.
 	 */
 	if (vfsp->vfs_flag & MS_REMOUNT) {
-		/* refresh mount options */
-		zfs_unregister_callbacks(vfsp->vfs_data);
+		zfsvfs_t *zfsvfs = vfsp->vfs_data;
+
+		/*
+		 * Refresh mount options with z_teardown_lock blocking I/O while
+		 * the filesystem is in an inconsistent state.
+		 * The lock also serializes this code with filesystem
+		 * manipulations between entry to zfs_suspend_fs() and return
+		 * from zfs_resume_fs().
+		 */
+		rrw_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG);
+		zfs_unregister_callbacks(zfsvfs);
 		error = zfs_register_callbacks(vfsp);
+		rrw_exit(&zfsvfs->z_teardown_lock, FTAG);
 		goto out;
 	}