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authorEric W. Biederman <ebiederm@xmission.com>2015-01-03 14:39:35 +0300
committerEric W. Biederman <ebiederm@xmission.com>2015-04-03 04:34:19 +0300
commit5d88457eb5b86b475422dc882f089203faaeedb5 (patch)
tree19d4a52f225092dfa2875dcb073d129151e910cf /fs/pnode.c
parent411a938b5abc9cb126c41cccf5975ae464fe0f3e (diff)
downloadlinux-5d88457eb5b86b475422dc882f089203faaeedb5.tar.xz
mnt: On an unmount propagate clearing of MNT_LOCKED
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. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/pnode.c')
-rw-r--r--fs/pnode.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/fs/pnode.c b/fs/pnode.c
index c27ae38ee250..89890293dd0a 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -362,6 +362,26 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
}
/*
+ * 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.
*/