From 9cc2c0f41c403a05989bc3ca2af650247d452f65 Mon Sep 17 00:00:00 2001 From: "T.kabe" Date: Mon, 6 Mar 2017 15:18:55 +0900 Subject: [PATCH 2/4] vfs: Keep a list of mounts on a mount point [upstream commit 0a5eb7c8189922e86a840972cd0b57e41de6f031] Author: Eric W. Biederman Date: Sun Sep 22 19:37:01 2013 -0700 vfs: Keep a list of mounts on a mount point To spot any possible problems call BUG if a mountpoint is put when it's list of mounts is not empty. AV: use hlist instead of list_head Reviewed-by: Miklos Szeredi Signed-off-by: Eric W. Biederman Signed-off-by: Al Viro --- fs/mount.h | 2 ++ fs/namespace.c | 6 ++++++ 2 files changed, 8 insertions(+) diff --git a/fs/mount.h b/fs/mount.h index b870800..92fecbe 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -21,6 +21,7 @@ struct mnt_pcp { struct mountpoint { struct list_head m_hash; struct dentry *m_dentry; + struct hlist_head m_list; int m_count; }; @@ -47,6 +48,7 @@ struct mount { struct mount *mnt_master; /* slave is on master->mnt_slave_list */ 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 */ #ifdef CONFIG_FSNOTIFY struct hlist_head mnt_fsnotify_marks; __u32 mnt_fsnotify_mask; diff --git a/fs/namespace.c b/fs/namespace.c index 0053bfc..c238481 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -197,6 +197,7 @@ static struct mount *alloc_vfsmnt(const char *name) INIT_LIST_HEAD(&mnt->mnt_share); INIT_LIST_HEAD(&mnt->mnt_slave_list); INIT_LIST_HEAD(&mnt->mnt_slave); + INIT_HLIST_NODE(&mnt->mnt_mp_list); #ifdef CONFIG_FSNOTIFY INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); #endif @@ -636,6 +637,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry) mp->m_dentry = dentry; mp->m_count = 1; list_add(&mp->m_hash, chain); + INIT_HLIST_HEAD(&mp->m_list); return mp; } @@ -643,6 +645,7 @@ static void put_mountpoint(struct mountpoint *mp) { if (!--mp->m_count) { struct dentry *dentry = mp->m_dentry; + BUG_ON(!hlist_empty(&mp->m_list)); spin_lock(&dentry->d_lock); dentry->d_flags &= ~DCACHE_MOUNTED; spin_unlock(&dentry->d_lock); @@ -689,6 +692,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path) mnt->mnt_mountpoint = mnt->mnt.mnt_root; list_del_init(&mnt->mnt_child); list_del_init(&mnt->mnt_hash); + hlist_del_init(&mnt->mnt_mp_list); put_mountpoint(mnt->mnt_mp); mnt->mnt_mp = NULL; } @@ -705,6 +709,7 @@ void mnt_set_mountpoint(struct mount *mnt, child_mnt->mnt_mountpoint = dget(mp->m_dentry); child_mnt->mnt_parent = mnt; child_mnt->mnt_mp = mp; + hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); } /* @@ -1207,6 +1212,7 @@ void umount_tree(struct mount *mnt, int propagate) __touch_mnt_namespace(p->mnt_ns); p->mnt_ns = NULL; if (mnt_has_parent(p)) { + hlist_del_init(&p->mnt_mp_list); p->mnt_parent->mnt_ghosts++; put_mountpoint(p->mnt_mp); p->mnt_mp = NULL; -- 1.8.3.1