diff options
| -rw-r--r-- | fs/mount.h | 1 | ||||
| -rw-r--r-- | fs/namespace.c | 27 |
2 files changed, 23 insertions, 5 deletions
diff --git a/fs/mount.h b/fs/mount.h index ad7173037924..b8beafdd6d24 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -92,6 +92,7 @@ struct mount { int mnt_expiry_mark; /* true if marked for expiry */ struct hlist_head mnt_pins; struct hlist_head mnt_stuck_children; + struct mount *overmount; /* mounted on ->mnt_root */ } __randomize_layout; #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ diff --git a/fs/namespace.c b/fs/namespace.c index 888816289154..9b732d74c2cc 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1043,6 +1043,9 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns) static struct mountpoint *unhash_mnt(struct mount *mnt) { struct mountpoint *mp; + struct mount *parent = mnt->mnt_parent; + if (unlikely(parent->overmount == mnt)) + parent->overmount = NULL; mnt->mnt_parent = mnt; mnt->mnt_mountpoint = mnt->mnt.mnt_root; list_del_init(&mnt->mnt_child); @@ -1078,6 +1081,8 @@ void mnt_set_mountpoint(struct mount *mnt, static void __attach_mnt(struct mount *mnt, struct mount *parent) { + if (unlikely(mnt->mnt_mountpoint == parent->mnt.mnt_root)) + parent->overmount = mnt; hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mnt->mnt_mountpoint)); list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); @@ -2660,7 +2665,9 @@ static int attach_recursive_mnt(struct mount *source_mnt, HLIST_HEAD(tree_list); struct mnt_namespace *ns = top_mnt->mnt_ns; struct mountpoint *smp; + struct mountpoint *secondary = NULL; struct mount *child, *dest_mnt, *p; + struct mount *top; struct hlist_node *n; int err = 0; bool moving = flags & MNT_TREE_MOVE, beneath = flags & MNT_TREE_BENEATH; @@ -2669,9 +2676,15 @@ static int attach_recursive_mnt(struct mount *source_mnt, * Preallocate a mountpoint in case the new mounts need to be * mounted beneath mounts on the same mountpoint. */ - smp = get_mountpoint(source_mnt->mnt.mnt_root); + for (top = source_mnt; unlikely(top->overmount); top = top->overmount) { + if (!secondary && is_mnt_ns_file(top->mnt.mnt_root)) + secondary = top->mnt_mp; + } + smp = get_mountpoint(top->mnt.mnt_root); if (IS_ERR(smp)) return PTR_ERR(smp); + if (!secondary) + secondary = smp; /* Is there space to add these mounts to the mount namespace? */ if (!moving) { @@ -2704,7 +2717,7 @@ static int attach_recursive_mnt(struct mount *source_mnt, unhash_mnt(source_mnt); mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); if (beneath) - mnt_change_mountpoint(source_mnt, smp, top_mnt); + mnt_change_mountpoint(top, smp, top_mnt); __attach_mnt(source_mnt, source_mnt->mnt_parent); mnt_notify_add(source_mnt); touch_mnt_namespace(source_mnt->mnt_ns); @@ -2719,7 +2732,7 @@ static int attach_recursive_mnt(struct mount *source_mnt, } mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); if (beneath) - mnt_change_mountpoint(source_mnt, smp, top_mnt); + mnt_change_mountpoint(top, smp, top_mnt); commit_tree(source_mnt); } @@ -2732,8 +2745,12 @@ static int attach_recursive_mnt(struct mount *source_mnt, child->mnt.mnt_flags &= ~MNT_LOCKED; q = __lookup_mnt(&child->mnt_parent->mnt, child->mnt_mountpoint); - if (q) - mnt_change_mountpoint(child, smp, q); + if (q) { + struct mount *r = child; + while (unlikely(r->overmount)) + r = r->overmount; + mnt_change_mountpoint(r, secondary, q); + } commit_tree(child); } put_mountpoint(smp); |