*/
__cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock);
+static inline void lock_mount_hash(void)
+{
+ write_seqlock(&mount_lock);
+}
+
+static inline void unlock_mount_hash(void)
+{
+ write_sequnlock(&mount_lock);
+}
+
static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry)
{
unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
/*
* vfsmount lock must be held for write
*/
-unsigned int mnt_get_count(struct mount *mnt)
+int mnt_get_count(struct mount *mnt)
{
#ifdef CONFIG_SMP
- unsigned int count = 0;
+ int count = 0;
int cpu;
for_each_possible_cpu(cpu) {
INIT_HLIST_NODE(&mnt->mnt_mp_list);
INIT_LIST_HEAD(&mnt->mnt_umounting);
INIT_HLIST_HEAD(&mnt->mnt_stuck_children);
+ mnt->mnt.mnt_userns = &init_user_ns;
}
return mnt;
{
int ret = 0;
- lock_mount_hash();
mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
/*
* After storing MNT_WRITE_HOLD, we'll read the counters. This store
*/
smp_wmb();
mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
- unlock_mount_hash();
return ret;
}
-static int __mnt_unmake_readonly(struct mount *mnt)
-{
- lock_mount_hash();
- mnt->mnt.mnt_flags &= ~MNT_READONLY;
- unlock_mount_hash();
- return 0;
-}
-
int sb_prepare_remount_readonly(struct super_block *sb)
{
struct mount *mnt;
static void free_vfsmnt(struct mount *mnt)
{
+ struct user_namespace *mnt_userns;
+
+ mnt_userns = mnt_user_ns(&mnt->mnt);
+ if (mnt_userns != &init_user_ns)
+ put_user_ns(mnt_userns);
kfree_const(mnt->mnt_devname);
#ifdef CONFIG_SMP
free_percpu(mnt->mnt_pcp);
mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
atomic_inc(&sb->s_active);
+ mnt->mnt.mnt_userns = mnt_user_ns(&old->mnt);
+ if (mnt->mnt.mnt_userns != &init_user_ns)
+ mnt->mnt.mnt_userns = get_user_ns(mnt->mnt.mnt_userns);
mnt->mnt.mnt_sb = sb;
mnt->mnt.mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt.mnt_root;
static void mntput_no_expire(struct mount *mnt)
{
LIST_HEAD(list);
+ int count;
rcu_read_lock();
if (likely(READ_ONCE(mnt->mnt_ns))) {
*/
smp_mb();
mnt_add_count(mnt, -1);
- if (mnt_get_count(mnt)) {
+ count = mnt_get_count(mnt);
+ if (count != 0) {
+ WARN_ON(count < 0);
rcu_read_unlock();
unlock_mount_hash();
return;
{
struct mount *mnt = real_mount(path->mnt);
- if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
- return -EINVAL;
if (!may_mount())
return -EPERM;
if (path->dentry != path->mnt->mnt_root)
return 0;
}
+// caller is responsible for flags being sane
int path_umount(struct path *path, int flags)
{
struct mount *mnt = real_mount(path->mnt);
struct path path;
int ret;
+ // basic validity checks done first
+ if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
+ return -EINVAL;
+
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
ret = user_path_at(AT_FDCWD, name, lookup_flags, &path);
if (readonly_request)
return mnt_make_readonly(mnt);
- return __mnt_unmake_readonly(mnt);
+ mnt->mnt.mnt_flags &= ~MNT_READONLY;
+ return 0;
}
-/*
- * Update the user-settable attributes on a mount. The caller must hold
- * sb->s_umount for writing.
- */
static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
{
- lock_mount_hash();
mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
mnt->mnt.mnt_flags = mnt_flags;
touch_mnt_namespace(mnt->mnt_ns);
- unlock_mount_hash();
}
static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt)
if (!can_change_locked_flags(mnt, mnt_flags))
return -EPERM;
- down_write(&sb->s_umount);
+ /*
+ * We're only checking whether the superblock is read-only not
+ * changing it, so only take down_read(&sb->s_umount).
+ */
+ down_read(&sb->s_umount);
+ lock_mount_hash();
ret = change_mount_ro_state(mnt, mnt_flags);
if (ret == 0)
set_mount_attributes(mnt, mnt_flags);
- up_write(&sb->s_umount);
+ unlock_mount_hash();
+ up_read(&sb->s_umount);
mnt_warn_timestamp_expiry(path, &mnt->mnt);
err = -EPERM;
if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
err = reconfigure_super(fc);
- if (!err)
+ if (!err) {
+ lock_mount_hash();
set_mount_attributes(mnt, mnt_flags);
+ unlock_mount_hash();
+ }
}
up_write(&sb->s_umount);
}