diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 47 |
1 files changed, 36 insertions, 11 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index e6c234b1a645..b5b1259e064f 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -96,10 +96,6 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry) return &mountpoint_hashtable[tmp & mp_hash_mask]; } -/* - * allocation is serialized by namespace_sem, but we need the spinlock to - * serialize with freeing. - */ static int mnt_alloc_id(struct mount *mnt) { int res; @@ -678,7 +674,7 @@ out: * * lookup_mnt takes a reference to the found vfsmount. */ -struct vfsmount *lookup_mnt(struct path *path) +struct vfsmount *lookup_mnt(const struct path *path) { struct mount *child_mnt; struct vfsmount *m; @@ -1034,6 +1030,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, if (IS_MNT_SLAVE(old)) list_add(&mnt->mnt_slave, &old->mnt_slave); mnt->mnt_master = old->mnt_master; + } else { + CLEAR_MNT_SHARED(mnt); } if (flag & CL_MAKE_SHARED) set_mnt_shared(mnt); @@ -1159,7 +1157,36 @@ struct vfsmount *mntget(struct vfsmount *mnt) } EXPORT_SYMBOL(mntget); -struct vfsmount *mnt_clone_internal(struct path *path) +/* path_is_mountpoint() - Check if path is a mount in the current + * namespace. + * + * d_mountpoint() can only be used reliably to establish if a dentry is + * not mounted in any namespace and that common case is handled inline. + * d_mountpoint() isn't aware of the possibility there may be multiple + * mounts using a given dentry in a different namespace. This function + * checks if the passed in path is a mountpoint rather than the dentry + * alone. + */ +bool path_is_mountpoint(const struct path *path) +{ + unsigned seq; + bool res; + + if (!d_mountpoint(path->dentry)) + return false; + + rcu_read_lock(); + do { + seq = read_seqbegin(&mount_lock); + res = __path_is_mountpoint(path); + } while (read_seqretry(&mount_lock, seq)); + rcu_read_unlock(); + + return res; +} +EXPORT_SYMBOL(path_is_mountpoint); + +struct vfsmount *mnt_clone_internal(const struct path *path) { struct mount *p; p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); @@ -1758,7 +1785,7 @@ out: /* Caller should check returned pointer for errors */ -struct vfsmount *collect_mounts(struct path *path) +struct vfsmount *collect_mounts(const struct path *path) { struct mount *tree; namespace_lock(); @@ -1791,7 +1818,7 @@ void drop_collected_mounts(struct vfsmount *mnt) * * Release with mntput(). */ -struct vfsmount *clone_private_mount(struct path *path) +struct vfsmount *clone_private_mount(const struct path *path) { struct mount *old_mnt = real_mount(path->mnt); struct mount *new_mnt; @@ -1799,9 +1826,7 @@ struct vfsmount *clone_private_mount(struct path *path) if (IS_MNT_UNBINDABLE(old_mnt)) return ERR_PTR(-EINVAL); - down_read(&namespace_sem); new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); - up_read(&namespace_sem); if (IS_ERR(new_mnt)) return ERR_CAST(new_mnt); @@ -2997,7 +3022,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry, return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); } -bool path_is_under(struct path *path1, struct path *path2) +bool path_is_under(const struct path *path1, const struct path *path2) { bool res; read_seqlock_excl(&mount_lock); |