diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 40 |
1 files changed, 33 insertions, 7 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index dcd015fafe01..777c3116e62e 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2823,6 +2823,7 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, int finish_automount(struct vfsmount *m, struct path *path) { + struct dentry *dentry = path->dentry; struct mount *mnt = real_mount(m); struct mountpoint *mp; int err; @@ -2832,21 +2833,46 @@ int finish_automount(struct vfsmount *m, struct path *path) BUG_ON(mnt_get_count(mnt) < 2); if (m->mnt_sb == path->mnt->mnt_sb && - m->mnt_root == path->dentry) { + m->mnt_root == dentry) { err = -ELOOP; - goto fail; + goto discard; } - mp = lock_mount(path); + /* + * we don't want to use lock_mount() - in this case finding something + * that overmounts our mountpoint to be means "quitely drop what we've + * got", not "try to mount it on top". + */ + inode_lock(dentry->d_inode); + namespace_lock(); + if (unlikely(cant_mount(dentry))) { + err = -ENOENT; + goto discard_locked; + } + rcu_read_lock(); + if (unlikely(__lookup_mnt(path->mnt, dentry))) { + rcu_read_unlock(); + err = 0; + goto discard_locked; + } + rcu_read_unlock(); + mp = get_mountpoint(dentry); if (IS_ERR(mp)) { err = PTR_ERR(mp); - goto fail; + goto discard_locked; } + err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); unlock_mount(mp); - if (!err) - return 0; -fail: + if (unlikely(err)) + goto discard; + mntput(m); + return 0; + +discard_locked: + namespace_unlock(); + inode_unlock(dentry->d_inode); +discard: /* remove m from any expiration list it may be on */ if (!list_empty(&mnt->mnt_expire)) { namespace_lock(); |