From 8614f45b2dfb72221688e12f0898f4a7aec0c5fb Mon Sep 17 00:00:00 2001 From: Andriy Gapon Date: Mon, 16 May 2016 07:23:24 +0000 Subject: [PATCH] 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 --- sys/kern/vfs_mount.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index 505da758ed4..0dfe3b6a43b 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -1298,7 +1298,8 @@ dounmount(struct mount *mp, int flags, struct thread *td) */ 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, struct thread *td) 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;