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dounmount: do not call mountcheckdirs() for mounts with MNT_IGNORE

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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
This commit is contained in:
Andriy Gapon 2016-05-16 07:23:24 +00:00
parent dfdc9a05c6
commit 8614f45b2d
1 changed files with 4 additions and 2 deletions
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6
sys/kern/vfs_mount.c
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@ -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;