svn commit: r299913 - head/sys/kern

[Andriy Gapon]

Author: avg
Date: Mon May 16 07:23:24 2016
New Revision: 299913
URL: https://svnweb.freebsd.org/changeset/base/299913

Log:
  dounmount: do not call mountcheckdirs() for mounts with MNT_IGNORE
  
  This is a bit hackish, but the flag is currently set only for ZFS
  snapshots mounted under .zfs.  mountcheckdirs() can change cdir/rdir
  references to a covered vnode.  But for the said snapshots the covered
  vnode is really ephemeral and it must never be accessed (except
  for a few specific cases).
  
  To do:	consider removing mountcheckdirs() entirely
  
  MFC after:	5 days

Modified:
  head/sys/kern/vfs_mount.c

Modified: head/sys/kern/vfs_mount.c
==============================================================================
--- head/sys/kern/vfs_mount.c	Mon May 16 07:19:33 2016	(r299912)
+++ head/sys/kern/vfs_mount.c	Mon May 16 07:23:24 2016	(r299913)
@@ -1298,7 +1298,8 @@ dounmount(struct mount *mp, int flags, s
 	 */
 	if ((flags & MNT_FORCE) &&
 	    VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
-		if (mp->mnt_vnodecovered != NULL)
+		if (mp->mnt_vnodecovered != NULL &&
+		    (mp->mnt_flag & MNT_IGNORE) == 0)
 			mountcheckdirs(fsrootvp, mp->mnt_vnodecovered);
 		if (fsrootvp == rootvnode) {
 			vrele(rootvnode);
@@ -1319,7 +1320,8 @@ dounmount(struct mount *mp, int flags, s
 	if (error && error != ENXIO) {
 		if ((flags & MNT_FORCE) &&
 		    VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
-			if (mp->mnt_vnodecovered != NULL)
+			if (mp->mnt_vnodecovered != NULL &&
+			    (mp->mnt_flag & MNT_IGNORE) == 0)
 				mountcheckdirs(mp->mnt_vnodecovered, fsrootvp);
 			if (rootvnode == NULL) {
 				rootvnode = fsrootvp;