diff options
| -rw-r--r-- | fs/mount.h | 2 | ||||
| -rw-r--r-- | fs/namespace.c | 2 | ||||
| -rw-r--r-- | fs/pnode.c | 144 |
3 files changed, 88 insertions, 60 deletions
diff --git a/fs/mount.h b/fs/mount.h index ede5a1d5cf99..de45d9e76748 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -58,7 +58,7 @@ struct mount { struct mnt_namespace *mnt_ns; /* containing namespace */ struct mountpoint *mnt_mp; /* where is it mounted */ struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */ - struct list_head mnt_reparent; /* reparent list entry */ + struct list_head mnt_umounting; /* list entry for umount propagation */ #ifdef CONFIG_FSNOTIFY struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; __u32 mnt_fsnotify_mask; diff --git a/fs/namespace.c b/fs/namespace.c index 51e49866e1fe..5e3dcbeb1de5 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -236,7 +236,7 @@ static struct mount *alloc_vfsmnt(const char *name) INIT_LIST_HEAD(&mnt->mnt_slave_list); INIT_LIST_HEAD(&mnt->mnt_slave); INIT_HLIST_NODE(&mnt->mnt_mp_list); - INIT_LIST_HEAD(&mnt->mnt_reparent); + INIT_LIST_HEAD(&mnt->mnt_umounting); init_fs_pin(&mnt->mnt_umount, drop_mountpoint); } return mnt; diff --git a/fs/pnode.c b/fs/pnode.c index 52aca0a118ff..fbaca7df2eb0 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -413,86 +413,95 @@ void propagate_mount_unlock(struct mount *mnt) } } -/* - * Mark all mounts that the MNT_LOCKED logic will allow to be unmounted. - */ -static void mark_umount_candidates(struct mount *mnt) +static void umount_one(struct mount *mnt, struct list_head *to_umount) { - struct mount *parent = mnt->mnt_parent; - struct mount *m; - - BUG_ON(parent == mnt); - - for (m = propagation_next(parent, parent); m; - m = propagation_next(m, parent)) { - struct mount *child = __lookup_mnt(&m->mnt, - mnt->mnt_mountpoint); - if (!child || (child->mnt.mnt_flags & MNT_UMOUNT)) - continue; - if (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m)) { - SET_MNT_MARK(child); - } - } + CLEAR_MNT_MARK(mnt); + mnt->mnt.mnt_flags |= MNT_UMOUNT; + list_del_init(&mnt->mnt_child); + list_del_init(&mnt->mnt_umounting); + list_move_tail(&mnt->mnt_list, to_umount); } /* * NOTE: unmounting 'mnt' naturally propagates to all other mounts its * parent propagates to. */ -static void __propagate_umount(struct mount *mnt, struct list_head *to_reparent) +static bool __propagate_umount(struct mount *mnt, + struct list_head *to_umount, + struct list_head *to_restore) { - struct mount *parent = mnt->mnt_parent; - struct mount *m; + bool progress = false; + struct mount *child; - BUG_ON(parent == mnt); + /* + * The state of the parent won't change if this mount is + * already unmounted or marked as without children. + */ + if (mnt->mnt.mnt_flags & (MNT_UMOUNT | MNT_MARKED)) + goto out; - for (m = propagation_next(parent, parent); m; - m = propagation_next(m, parent)) { - struct mount *topper; - struct mount *child = __lookup_mnt(&m->mnt, - mnt->mnt_mountpoint); - /* - * umount the child only if the child has no children - * and the child is marked safe to unmount. - */ - if (!child || !IS_MNT_MARKED(child)) + /* Verify topper is the only grandchild that has not been + * speculatively unmounted. + */ + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + if (child->mnt_mountpoint == mnt->mnt.mnt_root) continue; - CLEAR_MNT_MARK(child); + if (!list_empty(&child->mnt_umounting) && IS_MNT_MARKED(child)) + continue; + /* Found a mounted child */ + goto children; + } - /* If there is exactly one mount covering all of child - * replace child with that mount. - */ - topper = find_topper(child); - if (topper) - list_add_tail(&topper->mnt_reparent, to_reparent); + /* Mark mounts that can be unmounted if not locked */ + SET_MNT_MARK(mnt); + progress = true; - if (topper || list_empty(&child->mnt_mounts)) { - list_del_init(&child->mnt_child); - list_del_init(&child->mnt_reparent); - child->mnt.mnt_flags |= MNT_UMOUNT; - list_move_tail(&child->mnt_list, &mnt->mnt_list); + /* If a mount is without children and not locked umount it. */ + if (!IS_MNT_LOCKED(mnt)) { + umount_one(mnt, to_umount); + } else { +children: + list_move_tail(&mnt->mnt_umounting, to_restore); + } +out: + return progress; +} + +static void umount_list(struct list_head *to_umount, + struct list_head *to_restore) +{ + struct mount *mnt, *child, *tmp; + list_for_each_entry(mnt, to_umount, mnt_list) { + list_for_each_entry_safe(child, tmp, &mnt->mnt_mounts, mnt_child) { + /* topper? */ + if (child->mnt_mountpoint == mnt->mnt.mnt_root) + list_move_tail(&child->mnt_umounting, to_restore); + else + umount_one(child, to_umount); } } } -static void reparent_mounts(struct list_head *to_reparent) +static void restore_mounts(struct list_head *to_restore) { - while (!list_empty(to_reparent)) { + /* Restore mounts to a clean working state */ + while (!list_empty(to_restore)) { struct mount *mnt, *parent; struct mountpoint *mp; - mnt = list_first_entry(to_reparent, struct mount, mnt_reparent); - list_del_init(&mnt->mnt_reparent); + mnt = list_first_entry(to_restore, struct mount, mnt_umounting); + CLEAR_MNT_MARK(mnt); + list_del_init(&mnt->mnt_umounting); - /* Where should this mount be reparented to? */ + /* Should this mount be reparented? */ mp = mnt->mnt_mp; parent = mnt->mnt_parent; while (parent->mnt.mnt_flags & MNT_UMOUNT) { mp = parent->mnt_mp; parent = parent->mnt_parent; } - - mnt_change_mountpoint(parent, mp, mnt); + if (parent != mnt->mnt_parent) + mnt_change_mountpoint(parent, mp, mnt); } } @@ -506,15 +515,34 @@ static void reparent_mounts(struct list_head *to_reparent) int propagate_umount(struct list_head *list) { struct mount *mnt; - LIST_HEAD(to_reparent); + LIST_HEAD(to_restore); + LIST_HEAD(to_umount); - list_for_each_entry_reverse(mnt, list, mnt_list) - mark_umount_candidates(mnt); + list_for_each_entry(mnt, list, mnt_list) { + struct mount *parent = mnt->mnt_parent; + struct mount *m; - list_for_each_entry(mnt, list, mnt_list) - __propagate_umount(mnt, &to_reparent); + for (m = propagation_next(parent, parent); m; + m = propagation_next(m, parent)) { + struct mount *child = __lookup_mnt(&m->mnt, + mnt->mnt_mountpoint); + if (!child) + continue; + + /* Check the child and parents while progress is made */ + while (__propagate_umount(child, + &to_umount, &to_restore)) { + /* Is the parent a umount candidate? */ + child = child->mnt_parent; + if (list_empty(&child->mnt_umounting)) + break; + } + } + } - reparent_mounts(&to_reparent); + umount_list(&to_umount, &to_restore); + restore_mounts(&to_restore); + list_splice_tail(&to_umount, list); return 0; } |