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-rw-r--r--fs/pnode.c61
1 files changed, 49 insertions, 12 deletions
diff --git a/fs/pnode.c b/fs/pnode.c
index 06a793f4ae38..5bc7896d122a 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -322,6 +322,21 @@ out:
return ret;
}
+static struct mount *find_topper(struct mount *mnt)
+{
+ /* If there is exactly one mount covering mnt completely return it. */
+ struct mount *child;
+
+ if (!list_is_singular(&mnt->mnt_mounts))
+ return NULL;
+
+ child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child);
+ if (child->mnt_mountpoint != mnt->mnt.mnt_root)
+ return NULL;
+
+ return child;
+}
+
/*
* return true if the refcount is greater than count
*/
@@ -342,9 +357,8 @@ static inline int do_refcount_check(struct mount *mnt, int count)
*/
int propagate_mount_busy(struct mount *mnt, int refcnt)
{
- struct mount *m, *child;
+ struct mount *m, *child, *topper;
struct mount *parent = mnt->mnt_parent;
- int ret = 0;
if (mnt == parent)
return do_refcount_check(mnt, refcnt);
@@ -359,12 +373,24 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
- if (child && list_empty(&child->mnt_mounts) &&
- (ret = do_refcount_check(child, 1)))
- break;
+ int count = 1;
+ child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
+ if (!child)
+ continue;
+
+ /* Is there exactly one mount on the child that covers
+ * it completely whose reference should be ignored?
+ */
+ topper = find_topper(child);
+ if (topper)
+ count += 1;
+ else if (!list_empty(&child->mnt_mounts))
+ continue;
+
+ if (do_refcount_check(child, count))
+ return 1;
}
- return ret;
+ return 0;
}
/*
@@ -381,7 +407,7 @@ void propagate_mount_unlock(struct mount *mnt)
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
+ child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
if (child)
child->mnt.mnt_flags &= ~MNT_LOCKED;
}
@@ -399,9 +425,11 @@ static void mark_umount_candidates(struct mount *mnt)
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- struct mount *child = __lookup_mnt_last(&m->mnt,
+ struct mount *child = __lookup_mnt(&m->mnt,
mnt->mnt_mountpoint);
- if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) {
+ if (!child || (child->mnt.mnt_flags & MNT_UMOUNT))
+ continue;
+ if (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m)) {
SET_MNT_MARK(child);
}
}
@@ -420,8 +448,8 @@ static void __propagate_umount(struct mount *mnt)
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
-
- struct mount *child = __lookup_mnt_last(&m->mnt,
+ struct mount *topper;
+ struct mount *child = __lookup_mnt(&m->mnt,
mnt->mnt_mountpoint);
/*
* umount the child only if the child has no children
@@ -430,6 +458,15 @@ static void __propagate_umount(struct mount *mnt)
if (!child || !IS_MNT_MARKED(child))
continue;
CLEAR_MNT_MARK(child);
+
+ /* If there is exactly one mount covering all of child
+ * replace child with that mount.
+ */
+ topper = find_topper(child);
+ if (topper)
+ mnt_change_mountpoint(child->mnt_parent, child->mnt_mp,
+ topper);
+
if (list_empty(&child->mnt_mounts)) {
list_del_init(&child->mnt_child);
child->mnt.mnt_flags |= MNT_UMOUNT;