4.0-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Eric W. Biederman" <[email protected]> commit 5d88457eb5b86b475422dc882f089203faaeedb5 upstream. A prerequisite of calling umount_tree is that the point where the tree is mounted at is valid to unmount. If we are propagating the effect of the unmount clear MNT_LOCKED in every instance where the same filesystem is mounted on the same mountpoint in the mount tree, as we know (by virtue of the fact that umount_tree was called) that it is safe to reveal what is at that mountpoint. Signed-off-by: "Eric W. Biederman" <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/namespace.c | 3 +++ fs/pnode.c | 20 ++++++++++++++++++++ fs/pnode.h | 1 + 3 files changed, 24 insertions(+) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1335,6 +1335,9 @@ static void umount_tree(struct mount *mn LIST_HEAD(tmp_list); struct mount *p; + if (how & UMOUNT_PROPAGATE) + propagate_mount_unlock(mnt); + /* Gather the mounts to umount */ for (p = mnt; p; p = next_mnt(p, mnt)) { p->mnt.mnt_flags |= MNT_UMOUNT; --- a/fs/pnode.c +++ b/fs/pnode.c @@ -362,6 +362,26 @@ int propagate_mount_busy(struct mount *m } /* + * Clear MNT_LOCKED when it can be shown to be safe. + * + * mount_lock lock must be held for write + */ +void propagate_mount_unlock(struct mount *mnt) +{ + struct mount *parent = mnt->mnt_parent; + struct mount *m, *child; + + BUG_ON(parent == mnt); + + for (m = propagation_next(parent, parent); m; + m = propagation_next(m, parent)) { + child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint); + if (child) + child->mnt.mnt_flags &= ~MNT_LOCKED; + } +} + +/* * NOTE: unmounting 'mnt' naturally propagates to all other mounts its * parent propagates to. */ --- a/fs/pnode.h +++ b/fs/pnode.h @@ -42,6 +42,7 @@ int propagate_mnt(struct mount *, struct struct hlist_head *); int propagate_umount(struct list_head *); int propagate_mount_busy(struct mount *, int); +void propagate_mount_unlock(struct mount *); void mnt_release_group_id(struct mount *); int get_dominating_id(struct mount *mnt, const struct path *root); unsigned int mnt_get_count(struct mount *mnt); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
